Tianjin, China
Tianjin, China

Nankai University , often known as Nankai, is a public research university located in Tianjin mainland China. Founded in 1919 by prominent educators Zhang Boling and Yan Fansun , Nankai is one of the most prestigious universities in China. Its alumi include the former Premier Zhou Enlai and Nobel laureates Chen Ning Yang and Tsung-Dao Lee. Wikipedia.

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In the present study, a superhydrophobic polyurethane (PU) sponge with hierarchically structured surface, which exhibits excellent performance in absorbing oils/organic solvents, was fabricated for the first time through mussel-inspired one-step copolymerization approach. Specifically, dopamine (a small molecular bioadhesive) and n-dodecylthiol were copolymerized in an alkaline aqueous solution to generate polydopamine (PDA) nanoaggregates with n-dodecylthiol motifs on the surface of the PU sponge skeletons. Then, the superhydrophobic sponge that comprised a hierarchical structured surface similar to the chemical/topological structures of lotus leaf was fabricated. The topological structures, surface wettability, and mechanical property of the sponge were characterized by scanning electron microscopy, contact angle experiments, and compression test. Just as a result of the highly porous structure, superhydrophobic property and strong mechanical stability, this sponge exhibited desirable absorption capability of oils/organic solvents (weight gains ranging from 2494% to 8670%), suggesting a promising sorbents for the removal of oily pollutants from water. Furthermore, thanks to the nonutilization of the complicated processes or sophisticated equipment, the fabrication of the superhydrophobic sponge seemed to be quite easy to scale up. All these merits make the sponge a competitive candidate when compared to the conventional absorbents, for example, nonwoven polypropylene fabric. © 2014 American Chemical Society.

Zhao H.,Nankai University | Meng X.,Nankai University | Meng X.,Tianjin University of Technology | Huang Y.,Nankai University
Chemical Communications | Year: 2013

PPh3-Catalyzed aza-MBH domino reaction of salicyl N-tosylimines with γ-CH3 substituted allenoates is reported. Readily available imines and allenoates are converted to benzoxazepine derivatives in one step. Wherein, functionalization of C-H bonds of γ-substituted allenoate has been developed in this domino process. © 2013 The Royal Society of Chemistry.

Wang H.,Nanjing University of Posts and Telecommunications | Deng S.,Nankai University
Nonlinear Analysis: Real World Applications | Year: 2013

A Finsler manifold (M,F) is called Einstein if its Ricci scalar does not depend on the flagpole. We obtain new examples of homogenous Einstein-Randers metrics on some Stiefel manifolds SO(n)SO(l), as well as the symplectic analogs Sp(n)Sp(l). An existence result of invariant Einstein-Randers metrics is also obtained on these homogeneous manifolds. We also give a classification of these metrics under isometries and determine their group of isometries. © 2012 Published by Elsevier Ltd.

Chen D.-M.,Nankai University | Shi W.,Nankai University | Cheng P.,Nankai University
Chemical Communications | Year: 2015

A cage-based cationic body-centered metal-organic framework was successfully synthesized using a custom-designed bifunctional triazolcarboxylate ligand. It shows interesting single-crystal-to-single-crystal transformation upon solvent exchange process and selective uptake of organic dyes. This journal is © The Royal Society of Chemistry.

Han Z.-L.,Nankai University | Ding R.,Peking University | Liao Y.,Nankai University | Liao Y.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In this paper, we thoroughly investigate the LHC phenomenology of the type II seesaw mechanism for neutrino masses in the nondegenerate case where the triplet scalars of various charge (H±±,H±,H0,A0) have different masses. Compared with the degenerate case, the cascade decays of scalars lead to many new, interesting signal channels. In the positive scenario where MH±±MH±>MH0/A0, the detection of H±± is more challenging, when the cascade decay H±±→H±W±∗ is dominant. The most important channel is the associated H±H0/A0 production in the final state ℓ±ETbb-bb-, which requires a luminosity of 109 fb-1 for a 5σ discovery, while the final state ℓ±ETbb-τ+τ- is less promising. Moreover, the associated H0A0 production can give the same signals as the standard model Higgs pair production. With a much larger cross section, the H0A0 production in the final state bb-τ+τ- could reach 3σ significance at 14 TeV LHC with a luminosity of 300 fb-1. In summary, with an integrated luminosity ∼O(500 fb-1), the triplet scalars can be fully reconstructed at 14 TeV LHC in the negative scenario. © 2015 American Physical Society.

Chen R.,Lanzhou University | Liu X.,Nankai University | Li X.-Q.,Beijing University of Technology | Li X.-Q.,Peking University | Zhu S.-L.,Lanzhou University
Physical Review Letters | Year: 2015

The LHCb Collaboration at the Large Hadron Collider at CERN discovered two pentaquark states Pc(4380) and Pc(4450). These two hidden-charm states are interpreted as the loosely bound Σc(2455)D∗ and Σc∗(2520)D∗ molecular states in the boson exchange interaction model, which provides an explanation for why the experimental width of Pc(4450) is much narrower than that of Pc(4380). The discovery of the new resonances Pc(4380) and Pc(4450), indeed, opens a new page for hadron physics. The partners of Pc(4380) and Pc(4450) should be pursued in future experiments. © 2015 American Physical Society.

Zi G.,Beijing Normal University | Zhang F.,Beijing Normal University | Song H.,Nankai University
Chemical Communications | Year: 2010

A highly enantioselective group 5 metal amide catalyst system is reported for the hydroaminoalkylation of secondary amines to give chiral amines in good yields with excellent ee values (up to 93%) by loading of 5% precatalyst. © 2010 The Royal Society of Chemistry.

Han S.-D.,Nankai University | Zhao J.-P.,Nankai University | Zhao J.-P.,Tianjin University of Technology | Liu S.-J.,Nankai University | Bu X.-H.,Nankai University
Coordination Chemistry Reviews | Year: 2015

Hydro(solvo)thermal synthesis is a widely-used method to assemble various molecular magnetic materials based on different types of ligands. This review mainly focuses on the study of the magnetochemistry of azide/formate-mediated molecule-based magnetic materials of our lab synthesized under hydro(solvo)thermal conditions in the presence of coligand, with an emphasis on anionic coligand of carboxylate. The first section gives a brief discussion of azido and formato complexes and some important principles obtained from magneto-structural correlation; hydro(solvo)thermal synthetic strategies will also be referred to and elucidated in this part. The next six sections give overviews of the main results obtained in our group in recent years, that is, azide/formate-mediated ferromagnetism, ferrimagnetism, spin canting (or weak ferromagnetism), antiferromagnetism, single-molecule magnets (SMMs) and single-chain magnets (SCMs), and metamagnetism. Finally, the conclusions and perspectives of azido/formato-mediated molecular magnetic materials will be presented. Some of the trends identified could provide new insights into the further development of this promising area. © 2014 Elsevier B.V..

Liu K.,Nankai University | Shi W.,Nankai University | Cheng P.,Nankai University
Coordination Chemistry Reviews | Year: 2015

3d-4f heterometallic discrete complexes have enjoyed increasing attraction in recent decades because of their potential advantages to create new single-molecule magnets: the moderate magnetic couplings between 3d and 4f spin carriers and significant single-ion magnetic anisotropies of 4f ions. Herein we review the synthetic strategy, structures and magnetic properties of 3d-4f discrete complexes. Particular attention is paid in this review to the examples showing dynamics of the magnetization. © 2014 Elsevier B.V.

Xiang D.,CAS Beijing National Laboratory for Molecular | Xiang D.,Nankai University | Wang X.,CAS Beijing National Laboratory for Molecular | Jia C.,CAS Beijing National Laboratory for Molecular | And 3 more authors.
Chemical Reviews | Year: 2016

Creating functional electrical circuits using individual or ensemble molecules, often termed as "molecular-scale electronics", not only meets the increasing technical demands of the miniaturization of traditional Si-based electronic devices, but also provides an ideal window of exploring the intrinsic properties of materials at the molecular level. This Review covers the major advances with the most general applicability and emphasizes new insights into the development of efficient platform methodologies for building reliable molecular electronic devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication. First, we summarize a number of different approaches of forming molecular-scale junctions and discuss various experimental techniques for examining these nanoscale circuits in details. We then give a full introduction of characterization techniques and theoretical simulations for molecular electronics. Third, we highlight the major contributions and new concepts of integrating molecular functionalities into electrical circuits. Finally, we provide a critical discussion of limitations and main challenges that still exist for the development of molecular electronics. These analyses should be valuable for deeply understanding charge transport through molecular junctions, the device fabrication process, and the roadmap for future practical molecular electronics. © 2016 American Chemical Society.

Wang X.,Nankai University | Zhou M.,Nankai University | Jin X.,Tianjin University of Technology
Electrochimica Acta | Year: 2012

During last few years, large number of papers published on direct current glow discharge plasma (GDP) in and in contact with liquids due to the increasing interest for its application for wastewater treatment. In this paper, recent progress of GDP on wastewater treatment has been systematically reviewed, covering the degradation of organic pollutants, the reduction of Cr(VI) and the inactivation of algae. This contribution also provides comprehensive insights into reactors, generation mechanisms, physical characteristics, influence of operating parameters and energy efficiency comparing with other AOPs. The emphasis in this paper is on the mechanism of the removal of hazardous chemicals induced by GDP and the combined process. It ends by shortly mentioning theoretical fundamentals and promising actual application of GDP which call for further study. © 2012 Elsevier Ltd. All rights reserved.

Chen H.,Nankai University | Shahbazpanahi S.,University of Ontario Institute of Technology
IEEE Transactions on Signal Processing | Year: 2012

In filter-and-forward (FF) based two-way relay networks, each transmission for data exchange between two transceivers consists of only two time slots (or phases). In the first time slot, both transceivers transmit their data simultaneously to the relays. The received signal of each relay is filtered using a finite impulse response (FIR) filter to compensate for the frequency selectivity of the channels, and then, the output of the filter is forwarded to both transceivers in the second time-slot. In this paper, new approaches to distributed cooperative beamforming for such two-way relay networks with frequency selective channels are proposed. The first two distributed beamforming approaches assume that the transmitted powers of the transceivers are given and fixed. The first beamformer is based on minimizing the total transmitted power of the relays subject to two constraints on the signal-to-inter-symbol- interference-plus-noise ratio (SINR) at both transceivers. The second beamformer is designed through maximization of the lowest SINR of the two transceivers while keeping the relay transmitted power under certain levels. We show that these two problems can be cast as second-order convex cone programming problems. The other two distributed beamforming methods aim to calculate the transmitted powers of the transceivers as well as the coefficients of the relay filters using two different beamforming techniques. The first technique is based on the minimization of the total transmitted power of the transceivers and the relays subject to the SINR requirements for both transceivers, and the second method maximizes the lowest SINR of the two transceivers subject to a constraint on the total transmitted power. Simulation results demonstrate that using an FF relaying strategy can significantly improve the underlying performance measure as compared to the traditional amplify-and-forward relaying approach. © 2011 IEEE.

He L.,Singapore University of Technology and Design | Pan J.,University of Victoria | Xu J.,Nankai University
IEEE Transactions on Mobile Computing | Year: 2013

The introduction of mobile elements has created a new dimension to reduce and balance the energy consumption in wireless sensor networks. However, data collection latency may become higher due to the relatively slow travel speed of mobile elements. Thus, the scheduling of mobile elements, i.e., how they traverse through the sensing field and when they collect data from which sensor, is of ultimate importance and has attracted increasing attention from the research community. Formulated as the traveling salesman problem with neighborhoods (TSPN) and due to its NP-hardness, so far only approximation and heuristic algorithms have appeared in the literature, but the former only have theoretical value now due to their large approximation factors. In this paper, following a progressive optimization approach, we first propose a combine-skip-substitute (CSS) scheme, which is shown to be able to obtain solutions within a small range of the lower bound of the optimal solution. We then take the realistic multirate features of wireless communications into account, which have been ignored by most existing work, to further reduce the data collection latency with the multirate CSS (MR-CSS) scheme. Besides the correctness proof and performance analysis of the proposed schemes, we also show their efficiency and potentials for further extensions through extensive simulation. © 2002-2012 IEEE.

Huang X.,Peking University | Jiao N.,Peking University | Jiao N.,Nankai University
Organic and Biomolecular Chemistry | Year: 2014

A novel and efficient approach to alkenyl nitriles from readily available propargylic alcohols has been developed. This nitrogenation reaction is transition-metal-free and could be conducted under air at ambient temperature, which makes this protocol promising and practical. Moreover, NH4Br is disclosed as an efficient additive to promote the stereoselectivity of this reaction. © the Partner Organisations 2014.

Zhou J.,China Institute of Technology | Wan X.,China Institute of Technology | Liu Y.,China Institute of Technology | Zuo Y.,China Institute of Technology | And 7 more authors.
Journal of the American Chemical Society | Year: 2012

Small molecules, namely, DCAO 3TBDT and DR 3TBDT, with 2-ethylhexoxy substituted BDT as the central building block and octyl cyanoacetate and 3-ethylrhodanine as different terminal units with the same linkage of dioctyltertthiophene, have been designed and synthesized. The photovoltaic properties of these two molecules as donors and fullerene derivatives as the acceptors in bulk heterojunction solar cells are studied. Among them, DR 3TBDT shows excellent photovoltaic performance, and power conversion efficiency as high as 7.38% (certified 7.10%) under AM 1.5G irradiation (100 mW cm -2) has been achieved using the simple solution spin-coating fabrication process, which is the highest efficiency reported to date for any small-molecule-based solar cells. The results demonstrate that structure fine turning could cause significant performance difference and with that the performance of solution-processed small-molecule solar cells can indeed be comparable with or even surpass their polymer counterparts. © 2012 American Chemical Society.

Elliott R.J.R.,University of Birmingham | Sun P.,Nankai University | Chen S.,National University of Singapore
Energy Economics | Year: 2013

In this paper we investigate the relationship between the energy intensity of Chinese cities and the location of foreign firms employing a unique dataset of 206 of the largest prefecture-level cities between 2005 and 2008. Our results reveal a non linear inverted-U shaped relationship between energy intensity and city-level per capita income with the majority of cities on the downward slope of the curve. We also find evidence of a significant and negative relationship between the foreign direct investment (FDI) flows into a city and energy intensity. However, this effect varies by geographic location reflecting differences in the ability of regions to absorb and benefit from environmental spillovers. The relatively small economic effect of FDI can in part explained by the propensity for foreign firms to invest in energy intensive sectors coupled with the trend for China to invest heavily in capital intensive industries. © 2013 Elsevier B.V.

Liao Y.,Nankai University | Liao Y.,University of Heidelberg | Liao Y.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

When the standard model is viewed as a low energy effective theory, the neutrinos can obtain mass from higher dimensional operators. It has been known for long that such an operator first appears at mass dimension five and that it is unique. Here we show that the effective neutrino mass operator at every higher dimension is unique. This general claim is established using Young tableau, and illustrated by exhausting all potentially different operators at dimension seven. The result is relevant to the search of new physics effects beyond neutrino mass that can arise at a relatively low energy scale. © 2010 Elsevier B.V.

Chen J.-T.,Nankai University
Journal of Medicinal Chemistry | Year: 2013

A series of conjugated hyaluronic acid particles (HAP), composed of a hydrophobic anticancer drug core and hydrophilic cyclodextrin/hyaluronic acid shell, were prepared through self-assembling and characterized by 1H NMR titration, electron microscopy, zeta potential, and dynamic light-scattering experiments. The nanometer-sized HAP thus prepared was biocompatible and biodegradable and was well-recognized by the hyaluronic acid receptors overexpressed on the surface of cancer cells, which enabled us to exploit HAP as an efficient targeted delivery system for anticancer drugs. Indeed, HAP exhibited anticancer activities comparable to the commercial anticancer drug cisplatin but with lower side effects both in vitro and in vivo. © 2013 American Chemical Society.

Liang M.,Tianjin University of Technology | Liang M.,Nankai University | Chen J.,Nankai University
Chemical Society Reviews | Year: 2013

Arylamine organic dyes with donor (D), π-bridge (π) and acceptor (A) moieties for dye-sensitized solar cells (DSCs) have received great attention in the last decade because of their high molar absorption coefficient, low cost and structural variety. In the early stages, the efficiency of DSCs with arylamine organic dyes with D-π-A character was far behind that of DSCs with ruthenium(ii) complexes partly due to the lack of information about the relationship between the chemical structures and the photovoltaic performance. However, exciting progress has been recently made, and power conversion efficiencies over 10% were obtained for DSCs with arylamine organic dyes. It is thus that the recent research and development in the field of arylamine organic dyes employing an iodide/triiodide redox couple or polypyridyl cobalt redox shuttles as the electrolytes for either DSCs or solid-state DSCs has been summarized. The cell performance of the arylamine organic dyes are compared, providing a comprehensive overview of arylamine organic dyes, demonstrating the advantages/disadvantages of each class, and pointing out the field that needs to reinforce the research direction in the further application of DSCs. © 2013 The Royal Society of Chemistry.

Liao Y.,Nankai University | Liao Y.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We study higher-dimensional neutrino mass operators in a low energy theory that contains a second Higgs doublet, the two Higgs doublet model. The operators are relevant to underlying theories in which the lowest dimension-five mass operators would not be induced. We list the independent operators with dimension up to nine with the help of Young tableau. Also listed are the lowest dimension-seven operators that involve gauge bosons and violate the lepton number by two units. We briefly mention some of possible phenomenological implications. © 2011 Elsevier B.V.

To address the pollution that accompanies rapid industrial growth in China, a National Eco-industrial Park Demonstration Program was launched in 2000. This article provides a case study of the Tianjin Economic-Technological Development Area (TEDA). The emergence of an environmental institution in TEDA is used as a backdrop to assess how TEDA has transformed itself into one of the top three national eco-industrial parks in China. Following two years of field research, a network of 81 inter-firm symbiotic relationships formed in TEDA during the past 16 years were identified involving the utility, automobile, electronics, biotechnology, food and beverage, and resource recovery clusters. The article assesses the environmental benefits of the key symbiotic exchanges in TEDA and summarizes some unique characteristics of EIP progress in a developing country. © 2009 Elsevier Ltd. All rights reserved.

Zhang F.,Beijing Normal University | Song H.,Nankai University | Zi G.,Beijing Normal University
Dalton Transactions | Year: 2011

A new series of group 5 metal amides have been prepared from the reaction between V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) and chiral ligands, (R)-2,2′-bis(mesitoylamino)-1,1′- binaphthyl (1H2), (R)-5,5′,6,6′,7,7′,8,8′- octahydro-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (2H2), (R)-6,6′-dimethyl-2,2′-bis(mesitoylamino)-1,1′-biphenyl (3H2), (R)-2,2′-bis(mesitylenesulfonylamino)-6,6′- dimethyl-1,1′-biphenyl (4H2), (R)-2,2′- bis(diphenylthiophosphoramino)-1,1′-binaphthyl (5H2), (R)-2,2′-bis[(3-tert-butyl-2-hydroxybenzylidene)amino]-6, 6′-dimethyl-1,1′-biphenyl (6H2), (R)-2,2′-bis[(3,5- di-tert-butyl-2-hydroxybenzylidene)amino]-6,6′-dimethyl-1, 1′-biphenyl (7H2), (R)-2,2′-bis[(3-tert-butyl-2- hydroxybenzylidene)amino]-1,1′-binaphthyl (8H2), (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (9H), and (R)-2-(mesitoylamino)-2′-(dimethylamino)-6,6′-dimethyl-1, 1′-biphenyl (10H), which are derived from (R) or (S)-2,2′-diamino-1, 1′-binaphthyl, and (R)-2,2′-diamino-6,6′-dimethyl-1,1′- biphenyl, respectively. Treatment of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 1 equiv of C 2-symmetric amidate ligands 1H2, 2H2, 3H 2, 4H2, and 5H2, or Schiff base ligands 6H 2, 7H2 and 8H2 at room temperature gives, after recrystallization from a benzene, toluene or n-hexane solution, the vanadium amides (1)V(NMe2)2 (11), (2)V(NMe2)2 (14), (3)V(NMe2)2 (17), (5)V(NMe2)2 (22), (6)V(NMe2)2 (23) and (7)V(NMe2) 2 (24), and niobium amides (1)Nb(NMe2)3 (12), (2)Nb(NMe2)3 (15), (3)Nb(NMe2)3 (18), (4)Nb(NMe2)3 (20) and [2-(3-Me3C-2-O- C6H3CHN)-2′-(N)-C20H12][2- (Me2N)2CH-6-CMe3-C6H 3O]NbNMe2·C7H8 (25·C7H8), and tantalum amides (1)Ta(NMe 2)3 (13), (2)Ta(NMe2)3 (16), (3)Ta(NMe2)3 (19) and (4)Ta(NMe2)3 (21) respectively, in good yields. Reaction of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 2 equiv of C 1-symmetric amidate ligands 9H or 10H at room temperature gives, after recrystallization from a toluene or n-hexane solution, the chiral bis-ligated vanadium amides (9)2V(NMe2) 2·3C7H8 (27·3C7H 8) and (10)V(NMe2)2 (28), and chiral bis-ligated metallaaziridine complexes (10)2M(NMe2) (η2-CH2NMe) (M = Nb (29), Ta (30)) respectively, in good yields. The niobium and tantalum amidate complexes are stable in a toluene solution at or below 160 °C, while the vanadium amidate complexes degrade via diemthylamino group elimination at this temperature. For example, heating the complex (2)V(NMe2)2 (14) in toluene at 160 °C for four days leads to the isolation of the complex [(2)V]2(μ-NMe 2)2 (26) in 58% yield. These new complexes have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 12, 13, and 15-30 have further been confirmed by X-ray diffraction analyses. The vanadium amides are active chiral catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to good yields with good ee values (up to 80%), and the tantalum amides are outstanding chiral catalysts for the hydroaminoalkylation, giving chiral secondary amines in good yields with excellent ee values (up to 93%). © 2011 The Royal Society of Chemistry.

Ren L.,Peking University | Jiao N.,Peking University | Jiao N.,Nankai University
Chemical Communications | Year: 2014

A simple and readily available PdCl2 catalyzed carbamate synthesis method via isocyanate generation and application in situ has been developed. This chemistry provides an efficient and practical approach to synthesize carbamates from simple organic azides, CO atmosphere and alcohols. The broad scope, mild and neutral conditions, and only N2 as the byproduct make this transformation very useful. Moreover, simple examples of modification of bioactive molecules and construction of macrocycles were achieved through this protocol. This journal is © the Partner Organisations 2014.

Chen J.-L.,Nankai University | Yan X.-P.,Nankai University | Meng K.,Peking University | Wang S.-F.,Peking University
Analytical Chemistry | Year: 2011

While the super fluorescence quenching capacity of graphene and graphene oxide (GO) has been extensively employed to develop fluorescent sensors, their own unique fluorescence and its potential for chemo-/biosensing have seldom been explored. Here we report a GO-based photoinduced charge transfer (PCT) label-free near-infrared (near-IR) fluorescent biosensor for dopamine (DA). The multiple noncovalent interactions between GO and DA and the ultrafast decay at the picosecond range of the near-IR fluorescence of GO resulted in effective self-assembly of DA molecules on the surface of GO, and significant fluorescence quenching, allowing development of a PCT-based biosensor with direct readout of the near-IR fluorescence of GO for selective and sensitive detection of DA. The developed method gave a detection limit of 94 nM and a relative standard deviation of 2.0% for 11 replicate detections of 2.0 μM DA and was successfully applied to the determination of DA in biological fluids with quantitative recovery (98-115%). © 2011 American Chemical Society.

Zhang L.,Tianjin University of Technology | Yin Y.,Nankai University
Sensors and Actuators, B: Chemical | Year: 2013

In this contribution, hierarchical tin dioxide (SnO2) nanosheets were successfully synthesized via a simple, cost-effective and environment-friendly hydrothermal method at a relatively low temperature (90 C) after calcination in air. The post-heat treatment not only improved the crystallinity, but also increased the visible emission (refer to intrinsic crystal defects) of the hydrothermal products, which were proved by X-ray diffraction and room temperature photoluminescence, respectively. Electronmicroscopy analysis and nitrogen adsorption-desorption results confirmed the mesoporous feature of these nanosheets. Gas sensors based on these SnO 2 nanosheets exhibited high response, fast response-recovery and good selectivity to 1-1000 ppm ethanol vapor at a relatively low operating temperature (165 C). The excellent ethanol-sensing property, especially high response value can be mainly attributed to the mesoporous texture, characteristically small grain size, abundant surface defects, and the plane-contact feature between the neighboring SnO2 nanosheets. © 2013 Elsevier B.V.

Zhang L.,Tianjin University of Technology | Yin Y.,Nankai University
Sensors and Actuators, B: Chemical | Year: 2013

In this paper, flower-like zinc oxide (ZnO) nanorods were successfully synthesized via a simple, cost-effective and environment-friendly wet-chemical method at a relatively low temperature (90 C). X-ray diffraction indicated that the ZnO nanorods are crystallized in a hexagonal wurtzite structure. Electron microscopy observations confirmed the nanorod assembled flower-like morphology. And, high-resolution transmission electron microscopy (HRTEM) images proved that plenty of defects exist on the surface of ZnO nanorods. Photoluminescence analysis showed that abundant intrinsic defects are present on the ZnO crystal surfaces, the content of which is far more than that of commercial ZnO powders. X-ray photoelectron spectrometry revealed that considerable oxygen species (23.29%) chemisorbs on the surface of the as-prepared ZnO nanorods. Gas sensors based on these ZnO nanorods exhibit high response, fast response-recovery and good selectivity to 1-1000 ppm ethanol vapor at 400 C. The excellent ethanol-sensing performance, particularly high response values, is considered to be mainly originated from plenteous defects formed on ZnO surfaces. © 2013 Elsevier B.V. All rights reserved.

Li L.-B.,Nankai University | Hu J.-L.,National Chiao Tung University
Energy Policy | Year: 2012

Most existing energy efficiency indices are computed without taking into account undesirable outputs such as CO 2 and SO 2 emissions. This paper computes the ecological total-factor energy efficiency (ETFEE) of 30 regions in China for the period 2005-2009 through the slack-based model (SBM) with undesirable outputs. We calculate the ETFEE index by comparing the target energy input obtained from SBM with undesirable outputs to the actual energy input. Findings show that China's regional ETFEE still remains a low level of around 0.600 and regional energy efficiency is overestimated by more than 0.100 when not looking at environmental impacts. China's regional energy efficiency is extremely unbalanced: the east area ranks first with the highest ETFEE of above 0.700, the northeast and central areas follow, and the west area has the lowest ETFEE of less than 0.500. A monotone increasing relation exists between the area's ETFEE and China's per capita GDP. The truncated regression model shows that the ratio of R&D expenditure to GDP and the degree of foreign dependence have positive impacts, whereas the ratio of the secondary industry to GDP and the ratio of government subsidies for industrial pollution treatment to GDP have negative effects, on the ETFEE. © 2012 Elsevier Ltd.

Shen H.,Nankai University | Toki H.,Osaka University | Oyamatsu K.,Aichi Shukutoku University | Sumiyoshi K.,High Energy Accelerator Research Organization
Astrophysical Journal, Supplement Series | Year: 2011

We construct the equation of state (EOS) of dense matter covering a wide range of temperature, proton fraction, and density for the use of core-collapse supernova simulations. The study is based on the relativistic mean-field (RMF) theory, which can provide an excellent description of nuclear matter and finite nuclei. The Thomas-Fermi approximation in combination with assumed nucleon distribution functions and a free energy minimization is adopted to describe the non-uniform matter, which is composed of a lattice of heavy nuclei. We treat the uniform matter and non-uniform matter consistently using the same RMF theory. We present two sets of EOS tables, namely EOS2 and EOS3. EOS2 is an update of our earlier work published in 1998 (EOS1), where only the nucleon degree of freedom is taken into account. EOS3 includes additional contributions from Λ hyperons. The effect of Λ hyperons on the EOS is negligible in the low-temperature and low-density region, whereas it tends to soften the EOS at high density. In comparison with EOS1, EOS2 and EOS3 have an improved design of ranges and grids, which covers the temperature range T = 0.1-10 2.6MeV with the logarithmic grid spacing Δlog 10(T/[MeV]) = 0.04 (92points including T = 0), the proton fraction range Yp = 0-0.65 with the linear grid spacing ΔYp = 0.01 (66points), and the density range ρB = 10 5.1-1016 g cm-3 with the logarithmic grid spacing Δlog10(ρB/[g cm-3]) = 0.1 (110points). © 2011. The American Astronomical Society. All rights reserved.

Choi T.-M.,Hong Kong Polytechnic University | Li Y.,Nankai University | Xu L.,Tianjin University of Technology
International Journal of Production Economics | Year: 2013

The business values of product remanufacturing have been well-recognized in the literature. Companies have also increasingly realized the importance of coordinating the closed-loop supply chains (CLSCs) with both manufacturing and re-manufacturing processes. In this paper, we investigate a CLSC which consists of a retailer, a collector, and a manufacturer, and examine the performance of different CLSC under different channel leadership. Through a systematic comparison, we find that the retailer-led model gives the most effective CLSC. Moreover, we analytically reveal that the remanufacturing system's efficiency is highly related to a supply chain agent's proximity to the market. Counter-intuitively, we show that the collector-led model is not the most effective model for collecting the used-product. We finally illustrate how both the serial and parallel CLSCs can be coordinated by using different kinds of practical contracts. © 2013 Elsevier B.V.

Liao Y.,Peking University | Liao Y.,Nankai University
Journal of High Energy Physics | Year: 2011

The accessibility to physics responsible for tiny neutrino mass suggests that the mass should better originate from certain higher dimensional operators. The conventional three types of seesaw operate at dimension five with the help of either a new fermion or scalar multiplet. Here we propose a seesaw that generates neutrino mass through a dimension-(5 + 4n) operator. The seesaw is functioned by a fermion of isospin n + 1 and zero hypercharge and a sequence of scalar multiplets that share unity hypercharge but have isospin from 3 2 to n+ 1 2 at a step of unity. Only the scalar of the highest isospin can couple to the relevant fermions while only the scalar of the lowest isospin can directly develop a naturally small vacuum expectation value (VEV). The VEV is then transmitted to scalars of higher isospin through a cascading process. No global symmetry is required to forbid lower dimensional operators. A neutrino mass of desired order can thus be induced with a relatively low seesaw scale without demanding too small couplings. © SISSA 2011.

Li Y.,Nankai University | Xu L.,Nankai University | Xu L.,Tianjin University of Technology | Li D.,University of Minnesota
International Journal of Production Economics | Year: 2013

In online direct selling, a customer will not experience the product when making the purchase decision. Concerns about product quality and the return policy may prevent the customer from buying the product. In this paper, we develop several theoretical models to examine the impact of online distributor's return policy, product quality and pricing strategy on the customer's purchase and the return decisions. We categorize customers based on their purchase and return behaviors and discriminate distributors based on whether they position their strategy as cost- or price-driven. We find that decisions about the return policy are mutual and complementary with product quality and pricing strategies. In addition, we study direct distributor's pricing strategy, the return policy and the quality policy in four scenarios. The scenarios include situations where customer's demand is sensitive to price or the return policy, as well as where return is sensitive to the return policy or quality. Further, a special case with full refund is analyzed. Finally, we provide a numerical example to simulate the effects of demand sensitivity and return sensitivity on distributor's decisions and profits. © 2013 Elsevier B.V.

Sun J.-P.,Beijing Normal University | Li L.-C.,Nankai University | Zheng X.-J.,Beijing Normal University
Inorganic Chemistry Communications | Year: 2011

A cubane-like tetranuclear nickel(II) compound [Ni4(L) 4Cl4(H2O)3(C2H 5OH)]·H2O (1) and a binuclear iron(III) compound Fe2(L)2Cl4 (2) (HL = 2-pyridinemethanol) have been prepared by solvothermal reaction of metal chloride and 2-pyridinecarboxaldehyde in C2H5OH, in which 2-pyridinecarboxaldehyde was in situ reduced to 2-pyridinemethanol. The single crystal X-ray diffraction analysis suggests that the cluster core of [Ni 4(μ3-O)4] in 1 is formed by four Ni(II) and four alkoxide oxygen atoms at alternating corners, and the binuclear iron complex 2 is almost co-planar structure with alkoxide oxygen atom in μ2-mode. The magnetic studies reveal the ferromagnetic behavior for 1 and the anti-ferromagnetic interaction for 2. © 2011 Elsevier B.V.

Jiang H.-X.,Nankai University | Kong D.-M.,Nankai University | Shen H.-X.,Nankai University
Biosensors and Bioelectronics | Year: 2014

As two commonly used tool enzymes, DNA ligase and polynucleotide kinase/phosphatase (PNKP) play important roles in DNA metabolism. More and more studies show that regulation of their activity represents promising means for cancer therapy. To detect the activity of DNA ligase with high sensitivity and specificity, a G-quadruplex DNAzyme-based DNA ligase sensor was developed. In this sensor, the use of G-quadruplex DNAzyme eliminated the needs for any labeled oligonucleotide probes, thus making label-free detection possible. The introduction of rolling circle amplification (RCA) reaction could lead to the formation of multimeric G-quadruplexes containing thousands of G-quadruplex units, which can provide highly active hemin-binding sites, thus significantly improving the sensitivity of the sensor. The proposed sensor allowed specific detection of T4 DNA ligase with a detection limit of 0.0019. U/mL. By adding a PNKP-triggered 5'-phosphroylation step of the template DNA, the above sensing strategy could be easily extended to the design of PNKP sensor. The established sensor allowed specific detection of T4 PNKP with a detection limit of 0.0018. U/mL. In addition, these two sensors could also be used for the studies on inhibitors of these two enzymes. © 2013 Elsevier B.V.

Yin H.,Peking University | Wang T.,Peking University | Jiao N.,Peking University | Jiao N.,Nankai University
Organic Letters | Year: 2014

Copper-catalyzed oxoazidation and alkoxyazidation of indoles has been developed. The dearomatization reaction which leads to versatile 3-azido indolenine and oxindole derivatives in moderate to good yields could be used in a further transformation. © 2014 American Chemical Society.

Sun Z.,Nankai University | Sun Z.,Tianjin University of Technology | Liang M.,Nankai University | Liang M.,Tianjin University of Technology | Chen J.,Nankai University
Accounts of Chemical Research | Year: 2015

ConspectusDye-sensitized solar cells (DSCs) have gained widespread attentions owing to their low production cost, tunable optical response, and high light-to-electricity conversion. In DSCs, the performance of redox mediators with iodide/triiodide or iodine-free redox couples is vital to internal quantum efficiency. For a long time, iodide/triiodide based electrolytes are the most widely used mediators because of their desirable kinetics. Recently, exciting progress has been made with respect to iodine-free metallorganic and pure organic redox shuttles. Their tunable redox potential and diverse electron transfer behaviors enable the rational screening of electrolyte composition for enhancing the light-to-electricity conversion efficiency of DSCs toward the Shockley-Queisser limit.In this Account, we emphasize on current knowledge of two distinct but interrelated interfacial processes (electron recombination and dye regeneration), particularly for DSCs with iodine-free redox couples. We show that a deeper understanding of electron transfer kinetics of the alternative redox couples is fundamental to develop rational strategies for cell optimization. Compared with iodine electrolyte, iodine-free metallorganic redox couples such as iron, cobalt, and nickel complexes display much faster electron transfer kinetics in dye regeneration and interfacial recombination. Evidently, rapid regeneration enables the employment of more positive metal complex for attaining a higher photovoltage. However, severe recombination reactions have to be well controlled by using several effective surface treatments such as the addition of Brönsted bases and atomic layer deposition. Although these methods offer different pathways in surface passivation, a trade-off between charge injection efficiency and electron diffusion length is always observed. It follows that an appropriate LUMO level of sensitizer is essential to ensure efficient electron injection at the passivated TiO2 surface. Apart from fast recombination behavior, bulky metal complexes suffer from inefficient charge transport. Thus, the combination of thinner TiO2 film and sensitizers with high mole extinction coefficient has been employed for both enhancing diffusion-limited current and maintaining light-harvesting efficiency. Unlike metal complexes, most of organic sulfur redox couples in DSCs exhibit slow recombination kinetics. This allows the use of thicker TiO2 film to achieve an optimized light harvesting. However, the concomitant sluggish behavior of dye regeneration requires the use of sensitizers with more positive HOMO level, which is beneficial to efficient regeneration. Moreover, lower level of TiO2 band edge in DSCs based on organic sulfur mediators hinders the achievement of desirable photovoltage, spurring future explorations on this class of redox mediator.Based on the comparison of electron transfer behavior between iodine-free metallorganic complexes and pure organic redox couples, we aim to provide a comprehensive Account of the intriguing interfacial processes in iodine-free DSCs as the key scientific point is linked with the kinetics of interfacial reactions. This demonstrates the advantages as well as disadvantages of each class of iodine-free electrolyte and should shed light on to judicious selection of the energy levels for redox mediators, sensitizers, and the conduction band of TiO2 for DSCs. The knowledge of the reaction kinetics in DSCs should be also beneficial to the interface engineering on recent developed perovskite cells. © 2015 American Chemical Society.

He X.-G.,Center for Theoretical science | Li T.,Peking University | Li X.-Q.,Nankai University | Tandean J.,Center for Theoretical science | Tsai H.-C.,Center for Theoretical science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

The direct-search experiment for dark matter performed by the CDMS II Collaboration has observed two candidate events. Although these events cannot be interpreted as significant evidence for the presence of weakly interacting massive particle (WIMP) dark matter (DM), the total CDMS II data have led to an improved upper-limit on the WIMP-nucleon spin-independent cross-section. We study some implications of these results for the simplest WIMP DM model, the SM+D, which extends the standard model (SM) by the addition of a real SM-singlet scalar field dubbed darkon to play the role of the DM. We find that, although the CDMS II data rule out a sizable portion of parameter space of the model, a large part of the parameter space is still allowed. We obtain strong correlations among the darkon mass, darkon-nucleon cross-section, mass of the Higgs boson, and branching ratio of its invisible decay. We point out that measurements of the Higgs invisible branching-ratio at the LHC can lift some possible ambiguities in determining the darkon mass from direct DM searches. © 2010 Elsevier B.V. All rights reserved.

Cui P.,Nankai University | Ma Y.-G.,Texas A&M University | Li H.-H.,Nankai University | Zhao B.,Nankai University | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

A zeolite-like microporous tetrazole-based metal-organic framework (MOF) with 24 nuclear zinc cages was synthesized and characterized. It exhibits high CO2 adsorption capacity up to 35.6 wt % (8.09 mmol/g) and excellent CO2/CH4 selectivity at 273 K/1 bar, being among the highest values known to date. Theoretical calculations based on simulated annealing techniques and periodic DFT revealed that CO2 is predominantly located around the inner surface of the cages through multipoint interactions, in particular, around the aromatic tetrazole rings. Importantly, it is the first time that multipoint interactions between CO2 molecules and frameworks resulting in high CO2 uptake are observed. © 2012 American Chemical Society.

Sun H.,Nankai University | Gerecke A.C.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Giger W.,Giger Research Consulting | Alder A.C.,Eawag - Swiss Federal Institute of Aquatic Science and Technology
Environmental Pollution | Year: 2011

This study focused on the occurrence of long-chain perfluorinated chemicals (PFCs) in anaerobically stabilized sewage sludges from 20 municipal WWTPs using current and historic samples to evaluate the levels of PFCs and to identify the relative importance of commercial and industrial sources. A quantitative analytical method was developed based on solvent extraction of the analytes and a LC-MS/MS system. For total perfluoralkyl carboxylates (PFCAs), the concentrations ranged from 14 to 50 μg/kg dry matter. Concentrations of perfluorooctane sulfonic acid (PFOS) ranged from 15 to 600 μg/kg dry matter. In three WWTPs, the PFOS levels were six to nine times higher than the average values measured in the other plants. These elevated PFOS concentrations did not correlate with higher levels of PFCAs, indicating specific additional local sources for PFOS at these WWTPs. Average concentrations in selected samples from the years 1993, 2002, and 2008 did not change significantly. © 2010 Elsevier Ltd. All rights reserved.

Huang L.,Nankai University | Mo X.,Peking University
Journal of Geometry and Physics | Year: 2012

Spherically symmetric Finsler metrics form a rich class of Finsler metrics. In this paper we find equations that characterize spherically symmetric Finsler metrics of scalar flag curvature. By using these equations, we construct infinitely many non-projectively flat spherically symmetric Finsler metrics of scalar curvature. © 2012 Elsevier B.V.

News Article | August 31, 2016
Site: www.nature.com

In a world of mobile devices, incremental improvements in the size, sustainability and efficiency of battery technology can have considerable economic ramifications. The global battery market is forecast to be worth US$120 billion a year by 2019, and the competition to lead the science is fierce. Chemist Jun Chen knows this well. His group at Nankai University in Tianjin attracted attention after it successfully created a rechargeable sodium–carbon dioxide battery in late 2015 ( et al. Angew. Chem. 55, 6482–6486; 2016). In principle, Na–CO batteries are more energy efficient than lithium-based rechargeable power packs, as well as cheaper because of the abundance of sodium and CO . But the performance of previous Na–CO batteries had been disappointing: the electrochemical reaction caused solid deposits to form on the cathode, preventing recharge. Chen's team overcame this by creating a cathode from a 3D carbon nanotube structure. The result was a battery with an energy density more than five times that of the lithium (Li)-ion batteries, widely used in mobile devices and nickel–metal hydride batteries, and with the ability to be recharged 200 times without any reduction in storage capacity. Chen is the chief investigator for energy conversion and storage research at the Collaborative Innovation Center of Chemical Science and Engineering (CICCSE), a partnership between Nankai University and Tianjin University. The government-funded centre is designed to link science with industry for the benefit of the economy, and is one of 38 collaborative innovation centres (CICs) established across the country since 2012. CICCSE is now home to 385 researchers drawn from academia and industry, most of whom are affiliated with the 2 universities. In response to a weakening low-cost manufacturing market, in 2011 then-Chinese president Hu Jintao's pushed to embed science in the Chinese economy. He called for greater collaboration between the country's top research groups and between science and industry. The CICs grew out of what became known as the 2011 Plan, and focus on fields ranging from aerospace and quantum technology to medicine and advanced materials. The links formed can be domestic or international and are frequently both. By exploiting the multidisciplinary nature of universities, the centres are intended to overcome some of the challenges to innovation that remain in China, including scattered resources and inefficient research planning. Jiannian Yao, a director of CICCSE and vice-president of China's science funding body for competitive grants, the National Natural Science Foundation of China, says that the centres foster cooperation between researchers and strengthen national innovation capacity and competitiveness. Yao compares the centres to other government-led collaborations such as the Australian Research Council's Centres of Excellence, Millennium Science Initiative in South America and Japan's World Premier International Research Center Initiative. CICs with a focus on natural science and engineering also act as hubs for the promotion of industry partnerships. These centres receive generous funding from the government — the CICCSE receives around 50 million yuan (US$7.5 million) each year — as well as flexibility in the selection of research projects and the recruitment of scientists (unusual freedoms within government programmes in China, according to Chen). Cong Cao, a science-policy analyst at the University of Nottingham in Ningbo, says that the “new normal” of the Chinese economy, referring to slowed growth, means that the government has had to look to science and technology, with programmes such as the CICs, as the way to restore dynamism. In 2007, the Progress of Science and Technology Law was passed. The law, which is often referred to as the Chinese Bayh–Dole Act — a celebrated 1980s US patent-rights law credited with accelerating US industrial innovation — enables the intellectual property generated by government-funded research to be commercialized by the research group that does the investigation. The law has made it much easier for research institutions such as Chen's to benefit from the work their researchers are doing. In the seven years after the enactment of the law, the number of domestic patents awarded to Chinese researchers increased more than five-fold. The legislation has also made research partnerships between universities and industry more attractive for both sides. Over the past four years in particular, Cao says, the Chinese government has introduced a range of policies “to emphasize innovation and reform of China's science and technology system to make it better and quicker to respond to demand from the economy”. This includes the launch of the thirteenth Five Year Plan in 2015, which put innovation in science and technology at the centre of China's development. And following Premier Li Keqiang's annual address to the National People's Congress in March, there have been further efforts to encourage co-operation between science and industry. Speaking to the 2,943 delegates in the Great Hall of the People in Beijing, Li echoed what President Xi Jinping had outlined in the Five Year Plan, using the word 'innovation' more than 50 times. The speech also included promises of new national science and technology programmes and science centres. By 2020, said Li, science and technology will account for 60% of the nation's economic growth. “We will implement the strategy of innovation-driven development, see that science and technology become more deeply embedded in the economy, and improve the overall quality and competitiveness of the real economy,” Li said. The government promised tax deductions for companies undertaking research and development; and, since the speech, it has begun efforts to substantially reduce the notorious red tape associated with government funding for research and to increase the income that Chinese scientists can receive for working on government-funded projects. Back at the CICCSE, Chen and his colleagues have secured a Chinese patent on their battery technology, one of 339 patents awarded to the centre's projects up until the end of 2015. They are now working on adjustments to scale the technology up and overcome the need for a pure CO environment. Chen expects to have an improved version in production in about two years. Chen's group is also collaborating with Tianjin-based Li-ion battery developer Lishen and with electronics manufacturer Samsung, on improvements to Li-ion batteries for devices such as electric cars. The CICCSE, like other centres, works with industry in three ways: companies are founding members of the centres and are represented on the board, Chinese petroleum giant Sinopec and the Tianjin Bohai Chemical Industry Group both have representatives on the CICCSE board, for example; the centre's researchers do joint research with industry on major national issues; and the companies fund research projects. Sinopec is currently funding research to improve hydrogen production for use in fuel processing and the chemical industry. The project is using nanofabrication techniques to increase the stability of nickel-based catalysts, which are used in the methane-steam reforming process to create hydrogen. The greater stability increases the efficiency so that alternative fuels such as ethanol can be used. The hydrogen can then be used to refine petroleum, particularly heavier crude oils. When complete, Sinopec will implement the new technology in a number of its fuel-processing plants. Yao says that another project has already seen crystallization technology developed by CICCSE researchers adopted by the pharmaceutical industry and increase revenue by nearly 4 billion yuan. Despite such success stories, there is concern that science is not yet playing a part in the Chinese economy in the way that Hu Jintao had hoped. There have been lots of the incremental improvements, but not yet an innovation that changes the market. Initiatives aimed at encouraging more innovation are beginning to show signs of success. The government says that there are now at least 81 million people in China who work in science and technology. But researchers and analysts say there is no guarantee that even successful programmes will continue without substantial change. Cong says that the nature of Chinese science policy means that change is never far away. Based on Li's statements at the 2016 National People's Congress, the 38 CICs are unlikely to be immune. The Ministry of Education may already be trying to put the premier's words into practice, says Cong. This means that “there could soon be different programmes put into place”, he says. For now the CICCSE is still receiving strong support from the ministry, which is responsible for the CIC programme. But Yao agrees that there is a risk that new policies, such as those put forward at this year's National People's Congress, and President Xi Jinping's efforts to create his own policy legacy, could mean the programme is superseded or significantly altered in coming years. This may not signal an end to the support for existing centres, but it could mean the central government introduces an updated version, perhaps rebranding the CICs as national laboratories. “The assessment of CICs should focus on how well the expected objectives are achieved; in other words, how well the centres address the major issues in science, technology and economic development,” says Yao. Yao is confident about CICCSE's future. By the end of 2015, he points out, the centres' researchers boasted not only hundreds of patents but also 295 contributions to high-quality journals. The move towards better collaboration between academics and industry in the hope of creating stronger links between science and economic and social needs has been occurring around the world over the past decade. After less than five years, it is still early days for China's experiment. But signs indicate that the country is on a promising path.

News Article | February 15, 2017
Site: phys.org

But all bets are off, if the students journey to the center of the Earth, à la Jules Verne's Otto Lidenbrock or if they venture to one of the solar system's large planets, such as Jupiter or Saturn. "That's because extremely high pressure, like that found at the Earth's core or giant neighbors, completely alters helium's chemistry," says Boldyrev, faculty member in USU's Department of Chemistry and Biochemistry. It's a surprising finding, he says, because, on Earth, helium is a chemically inert and unreactive compound that eschews connections with other elements and compounds. The first of the noble gases, helium features an extremely stable, closed-shell electronic configuration, leaving no openings for connections. Further, Boldyrev's colleagues confirmed computationally and experimentally that sodium, never an earthly comrade to helium, readily bonds with the standoffish gas under high pressure to form the curious Na He compound. These findings were so unexpected, Boldyrev says, that he and colleagues struggled for more than two years to convince science reviewers and editors to publish their results. Persistence paid off. Boldyrev and his doctoral student Ivan Popov, as members of an international research group led by Artem Oganov of Stony Brook University, published the pioneering findings in the Feb. 6, 2017, issue of Nature Chemistry. Additional authors on the paper include researchers from China's Nankai University, Center for High Pressure Science and Technology, Chinese Academy of Sciences, Northwestern Polytechnical University, Xi'an and Nanjing University; Russia's Skolkovo Institute of Science and Technology, Moscow Institute of Physics and Technology, Sobolev Institute of Geology and Mineralogy and RUDN University; the Carnegie Institution of Washington, Lawrence Livermore National Laboratory, Italy's University of Milan, the University of Chicago and Germany's Aachen University and Photo Science DESY. Boldyrev and Popov's role in the project was to interpret a chemical bonding in the computational model developed by Oganov and the experimental results generated by Carnegie's Alexander Goncharov. Initially, the Na He compound was found to consist of Na cubes, of which half were occupied by helium atoms and half were empty. "Yet, when we performed chemical bonding analysis of these structures, we found each 'empty' cube actually contained an eight-center, two-electron bond," Boldyrev says. "This bond is what's responsible for the stability of this enchanting compound." Their findings advanced the research to another step. "As we explore the structure of this compound, we're deciphering how this bond occurs and we predicted that, adding oxygen, we could create a similar compound," Popov says. Such knowledge raises big questions about chemistry and how elements behave beyond the world we know. Questions, Boldyrev says, Earth's inhabitants need to keep in mind as they consider long-term space travel. "With the recent discovery of multiple exoplanets, we're reminded of the vastness of the universe," he says. "Our understanding of chemistry has to change and expand beyond the confines of our own planet." Explore further: Scientists discover extraordinary compounds that may be hidden inside Jupiter and Neptune More information: A stable compound of helium and sodium at high pressure, Nature Chemistry, DOI: 10.1038/nchem.2716

News Article | December 7, 2015
Site: news.yahoo.com

China's first mind-controlled car has been developed by researchers in the north-east port city of Tianjin. Chinese researchers have developed what they say is the country's first car that uses nothing but brain power to drive. The research team from Nankai University, in the north-eastern Chinese port city of Tianjin, has spent two years bringing the mind-controlled vehicle to reality. By wearing brain signal-reading equipment a driver can control the car to go forward, backwards, come to a stop, and both lock and unlock the vehicle, all without moving their hands or feet. Researcher Zhang Zhao told Reuters the equipment comprises 16 sensors that capture EEG (electroencephalogram) signals from the driver's brain. They developed a computer program that selects the relevant signals and translates them, enabling control of the car. "The tester's EEG signals are picked up by this (brain signal-reading) equipment and transmitted wirelessly to the computer. The computer processes the signals to categorize and recognize people's intention, then translates them into control command to the car. The core of the whole flow is to process the EEG signals, which is done on the computer," said Zhang. Associate Professor Duan Feng, from the university's College of Computer and Control Engineering, led the project. He emphasized that the technology is aimed at better serving human beings, and that it might soon be possible to combine brain controlled technology and driverless cars, such as the Google Self Driving Car (SDC). "Driverless cars' further development can bring more benefits to us, since we can better realize functions relating to brain controlling with the help of the driverless cars' platform," said Duan. "In the end, cars, whether driverless or not, and machines are serving for people. Under such circumstances, people's intentions must be recognized. In our project, it makes the cars better serve human beings." Duan said worries about potential road accidents caused by the driver being distracted while their brain was in control of his team's car were unfounded, because concentration was needed only when changing the vehicle's moving status, i.e. changing lanes or turning. Whether such an application would be enough to persuade drivers to get behind the wheel and control a car with their mind is far from certain, though. The researchers say their initial idea was inspired by helping disabled people who are physically unable to steer cars. "There are two starting points of this project. The first one is to provide a driving method without using hands or feet for the disabled who are unable to move freely; and secondly, to provide healthy people with a new and more intellectualized driving mode," Zhang said. At present the vehicle, in collaboration with Chinese car manufacturer Great Wall Motor, can only drive in a straight direction, and there are no plans to put it into production.

Gu Z.,Nankai University | Zhang S.,Chongqing University of Posts and Telecommunications
International Journal of Production Economics | Year: 2012

Based on incomplete contract theories, we studied the strategic behaviors of up-stream and down-stream manufacturers by option game model and obtain some conclusions. First, the down-streams pay-off function is a concave function of its investment in fixed assets, so there is an optimal investment, which ensures the down-streams maximal pay-off and prevents it from being holdup. Second, in presence of endogenous default risks, the up-stream can improve its pay-off level through non-linear pricing. Last, increasing business risks of the down-stream may lead to an increased price fluctuation of the up-stream, while the down-streams technological advancement can make such fluctuation less. © 2010 Elsevier B.V. All rights reserved.

Perc M.,University of Maribor | Wang Z.,Nankai University
PLoS ONE | Year: 2010

To be the fittest is central to proliferation in evolutionary games. Individuals thus adopt the strategies of better performing players in the hope of successful reproduction. In structured populations the array of those that are eligible to act as strategy sources is bounded to the immediate neighbors of each individual. But which one of these strategy sources should potentially be copied? Previous research dealt with this question either by selecting the fittest or by selecting one player uniformly at random. Here we introduce a parameter u that interpolates between these two extreme options. Setting u equal to zero returns the random selection of the opponent, while positive u favor the fitter players. In addition, we divide the population into two groups. Players from group A select their opponents as dictated by the parameter u, while players from group B do so randomly irrespective of u. We denote the fraction of players contained in groups A and B by v and 1 - v, respectively. The two parameters u and v allow us to analyze in detail how aspirations in the context of the prisoner's dilemma game influence the evolution of cooperation. We find that for sufficiently positive values of u there exist a robust intermediate v≈0:5 for which cooperation thrives best. The robustness of this observation is tested against different levels of uncertainty in the strategy adoption process K and for different interaction networks. We also provide complete phase diagrams depicting the dependence of the impact of u and v for different values of K, and contrast the validity of our conclusions by means of an alternative model where individual aspiration levels are subject to evolution as well. Our study indicates that heterogeneity in aspirations may be key for the sustainability of cooperation in structured populations. © 2010 Perc, Wang.

Ge M.,Tianjin Key Laboratory of Environmental Remediation and Pollution Control | Li Y.,Nankai University | Liu L.,Tianjin Key Laboratory of Environmental Remediation and Pollution Control | Zhou Z.,Nankai University | Chen W.,Tianjin Key Laboratory of Environmental Remediation and Pollution Control
Journal of Physical Chemistry C | Year: 2011

Chrysanthemum-analogous Bi2O3?Bi2WO 6 composite microspheres, assembled by nanosheets, were synthesized through a one-step hydrothermal route with the aid of surfactant templates. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to clarify the structure and morphology of the Bi2O 3?Bi2WO6 microspheres. Nitrogen adsorption and desorption isotherms were conducted to examine the specific surface area and the pore nature of the as-prepared microspheres. The photocatalytic activity of the Bi2O3?Bi2WO6 composite microspheres was evaluated by using rhodamine B as a model contaminant, and over 99% of rhodamine B was degraded within 10 min under the exposure of sunlight. The Bi2O3?Bi2WO6 composite microspheres presented enhanced photocatalytic performances compared with separate Bi 2O3, Bi2WO6, and conventional P25. © 2011 American Chemical Society.

Zhang L.,Nankai University | Yu H.,Nankai University | Wang P.,Beijing Technology and Business University
Bioresource Technology | Year: 2013

With the aim to develop an ecologically viable catalytic pathway for furfural production without the use of inorganic acids, H3PW12O40, Amberlyst-5 and NKC-9 (macroporous styrene-based sulfonic acid resin) were used as catalysts for producing furfural from xylose, xylan and lignocellulosic biomass in [BMIM]Cl under microwave irradiation at atmospheric pressure. A surprisingly high furfural yield of 93.7% from xylan was obtained by H3PW12O40 at 160°C in 10min. The degradation of furfural affected by single addition of [BMIM]Cl and solid acids was also investigated. The IL could be easily recycled and reused with stable solvent capacity for multiple runs (5×) after the product furfural was extracted with ethyl acetate. © 2013 Elsevier Ltd.

Li C.-T.,University of Warwick | Li Y.,Nankai University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2012

The last few years have seen the use of photo response non-uniformity noise (PRNU), a unique fingerprint of imaging sensors, in various digital forensic applications such as source device identification, content integrity verification, and authentication. However, the use of a color filter array for capturing only one of the three color components per pixel introduces color interpolation noise, while the existing methods for extracting PRNU provide no effective means for addressing this issue. Because the artificial colors obtained through the color interpolation process are not directly acquired from the scene by physical hardware, we expect that the PRNU extracted from the physical components, which are free from interpolation noise, should be more reliable than that from the artificial channels, which carry interpolation noise. Based on this assumption we propose a couple-decoupled PRNU (CD-PRNU) extraction method, which first decomposes each color channel into four sub-images and then extracts the PRNU noise from each sub-image. The PRNU noise patterns of the sub-images are then assembled to get the CD-PRNU. This new method can prevent the interpolation noise from propagating into the physical components, thus improving the accuracy of device identification and image content integrity verification. © 2011 IEEE.

Wang Z.,Nankai University | Perc M.,University of Maribor
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Strategy changes are an essential part of evolutionary games. Here, we introduce a simple rule that, depending on the value of a single parameter w, influences the selection of players that are considered as potential sources of the new strategy. For positive w players with high payoffs will be considered more likely, while for negative w the opposite holds. Setting w equal to zero returns the frequently adopted random selection of the opponent. We find that increasing the probability of adopting the strategy from the fittest player within reach, i.e., setting w positive, promotes the evolution of cooperation. The robustness of this observation is tested against different levels of uncertainty in the strategy adoption process and for different interaction networks. Since the evolution to widespread defection is tightly associated with cooperators having a lower fitness than defectors, the fact that positive values of w facilitate cooperation is quite surprising. We show that the results can be explained by means of a negative feedback effect that increases the vulnerability of defectors although initially increasing their survivability. Moreover, we demonstrate that the introduction of w effectively alters the interaction network and thus also the impact of uncertainty by strategy adoptions on the evolution of cooperation. © 2010 The American Physical Society.

Zhang L.,Nankai University | Yu H.,Nankai University | Wang P.,Beijing Technology and Business University | Dong H.,Nankai University | Peng X.,Nankai University
Bioresource Technology | Year: 2013

In order to define a new green catalytic pathway for the production of furfural, the catalyzed conversion of xylan into furfural in 1-butyl-3-methylimidazolium chloride was studied by using mineral acids and metal chlorides as catalysts under microwave irradiation. Amongst these catalysts, AlCl3 resulted in the highest furfural yield of 84.8% at 170°C for 10s. The effect of AlCl3 on the conversion efficiency of d-xylose and untreated lignocellulosic biomass was also investigated, the yields of furfural from corncob, grass and pine wood catalyzed by AlCl3 in [BMIM]Cl were in the range of 16-33%. [BMIM]Cl and AlCl3 could be recycled for four runs with stable catalytic activity. AlCl3 is less corrosive than mineral acids, and the use of ionic liquid as reaction medium will no longer generate toxic wastewater, thus this reaction system is more ecologically viable. © 2012 Elsevier Ltd.

Du S.-Y.,CAS Institute of Physics | Du S.-Y.,Nankai University | Li Z.-Y.,CAS Institute of Physics
Optics Letters | Year: 2010

We propose a scheme to enhance near-UVband absorption of a rutile TiO 2 nanoparticle by placing Au nanoparticles in its neighborhood. The discrete-dipole approximation method was employed to calculate the absorption spectrum of pure rutile TiO2 and that of TiO2 mixed with Au nanoparticles. The results indicate that pure rutile TiO2 has its maximum absorption located in the deep-UV band. With the existence of Au nanoparticles, a significant light harvesting effect occurs, and this maximum shifts to the near-UV band, where usual excitation wavelength falls. © 2010 Optical Society of America.

Wang M.-M.,Nankai University | Wang M.-M.,Hebei United University | Yan X.-P.,Nankai University
Analytical Chemistry | Year: 2012

Graphene oxide (GO) has received great interest for its unique properties and potential diverse applications. Here, we show the fabrication of GO nanosheets incorporated monolithic column via one-step room temperature polymerization for capillary electrochromatography (CEC). GO is attractive as the stationary phase for CEC because it provides not only ionized oxygen-containing functional groups to modify electroendoosmotic flow (EOF) but also aromatic macromolecule to give hydrophobicity and π-π electrostatic stacking property. Incorporation of GO into monolithic column greatly increased the interactions between the tested neutral analytes (alkyl benzenes and polycyclic aromatics) and the stationary phase and significantly improved their CEC separation. Baseline separation of the tested neutral analytes on the GO incorporated monolithic column was achieved on the basis of typical reversed-phase separation mechanism. The precision (relative standard deviation (RSD), n = 3) of EOF was 0.3%, while the precision of retention time, peak area, and peak height for the tested neutral analytes were in the range of 0.4-3.0%, 0.8-4.0%, and 0.8-4.9%, respectively. In addition, a set of anilines were well separated on the GO incorporated monolith. The GO incorporated monolithic columns are promising for CEC separation. © 2011 American Chemical Society.

Wang B.,Institute of Materials Research and Engineering of Singapore | Zhang X.,Wuhan University | Garcia-Vidal F.J.,Autonomous University of Madrid | Yuan X.,Nankai University | Teng J.,Institute of Materials Research and Engineering of Singapore
Physical Review Letters | Year: 2012

Here we investigate theoretically and numerically the coupling between surface plasmon polaritons (SPPs) in monolayer graphene sheet arrays that have a period much smaller than the wavelength. We show that when the collective SPP is excited with an out-of-phase illumination, the beam tends to propagate toward the opposite direction of the Bloch momentum, reflecting a negative coupling between the constituent SPPs. In contrast, for in-phase illumination, the incident beam is split into two collective SPPs that are highly collimated and display low propagation loss. Moreover, the coupling between the individual SPPs results in a reduction of the modal wavelength of the SPP in comparison with that of a single graphene sheet. © 2012 American Physical Society.

Yang J.,University Paris - Sud | Sauvan C.,University Paris - Sud | Sauvan C.,Institut Universitaire de France | Liu H.T.,Nankai University | And 2 more authors.
Physical Review Letters | Year: 2011

We theoretically study fishnet metamaterials at optical frequencies. In contrast with earlier works, we provide a microscopic description by tracking the transversal and longitudinal flows of energy through the fishnet mesh composed of intersecting subwavelength plasmonic waveguides. The analysis is supported by a semianalytical model based on surface-plasmon coupled-mode equations, which provides accurate formulas for the fishnet refractive index, including the real-negative and imaginary parts. The model simply explains how the surface plasmons couple at the waveguide intersections, and it shines new light on the fishnet negative-index paradigm at optical frequencies. Extension of the theory for loss-compensated metamaterials with gain media is also presented. © 2011 American Physical Society.

Wang Z.,Nankai University | Wang Z.,Hong Kong Baptist University | Szolnoki A.,Hungarian Academy of Sciences | Perc M.,University of Maribor
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

While worldwide census data provide statistical evidence that firmly link the population density with several indicators of social welfare, the precise mechanisms underlying these observations are largely unknown. Here we study the impact of population density on the evolution of public cooperation in structured populations and find that the optimal density is uniquely related to the percolation threshold of the host graph irrespective of its topological details. We explain our observations by showing that spatial reciprocity peaks in the vicinity of the percolation threshold, when the emergence of a giant cooperative cluster is hindered neither by vacancy nor by invading defectors, thus discovering an intuitive yet universal law that links the population density with social prosperity. © 2012 American Physical Society.

Zhang L.,Nankai University | Yu H.,Nankai University | Wang P.,Beijing Technology and Business University | Li Y.,Nankai University
Bioresource Technology | Year: 2014

An efficient and simple one-pot monophasic reaction system with small carbon footprint for converting xylose, xylan and corncob into furfural was developed in gamma-valerolactone (GVL, an ideal sustainable solvent derived from lignocelluloses) by using FeCl3·6H2O as catalyst. Good yields of furfural from xylose were obtained, and the system was shown to work for xylan and corncob as well. A surprisingly high furfural yield of 79.6% from untreated corncob was achieved at 458K for 100min. Contrary to what was generally believed, the addition of water, reduced the rate of the reactions, but showed positive effect on preventing the furfural from degradation in GVL. Besides, the C6 sugars (glucose and cellulose) afforded 11.4-24.5% furfural yields when employing this catalytic approach. The reaction system proposed in this manuscript showed great potential for optimizing the catalytic process in furfural production. © 2013 Elsevier Ltd.

Cao K.,Nankai University | Jiao L.,Nankai University | Liu H.,Nankai University | Liu Y.,Nankai University | And 3 more authors.
Advanced Energy Materials | Year: 2015

To develop a long cycle life and good rate capability electrode, 3D hierarchical porous α-Fe2O3 nanosheets are fabricated on copper foil and directly used as binder-free anode for lithium-ion batteries. This electrode exhibits a high reversible capacity and excellent rate capability. A reversible capacity up to 877.7 mAh g-1 is maintained at 2 C (2.01 A g-1) after 1000 cycles, and even when the current is increased to 20 C (20.1 A g-1), a capacity of 433 mA h g-1 is retained. The unique porous 3D hierarchical nanostructure improves electronic-ionic transport, mitigates the internal mechanical stress induced by the volume variations of the electrode upon cycling, and forms a 3D conductive network during cycling. No addition of any electrochemically inactive conductive agents or polymer binders is required. Therefore, binder-free electrodes further avoid the uneven distribution of conductive carbon on the current collector due to physical mixing and the addition of an insulator (binder), which has benefits leading to outstanding electrochemical performance. 3D hierarchical porous α-Fe2O3 nanosheets on copper foil are successfully fabricated by a facile method. When used as binder-free anode material, these unique 3D hierarchical nanosheets with porous structure exhibit high reversible lithium-storage performance, outstanding rate capability, and excellent cycling stability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang Z.,Beijing University of Posts and Telecommunications | Long K.,National Laboratory of Switching Technology and Telecommunication Networks at BUPT | Wang J.,Nankai University
IEEE Wireless Communications | Year: 2013

Cognitive radio is regarded as a promising technology to provide high bandwidth to mobile users via heterogeneous wireless network architectures and dynamic spectrum access techniques. However, cognitive radio networks may also impose some challenges due to various factors such as the ever increasing complexity of network architecture, the high cost of configuring and managing large-scale networks, the fluctuating nature of the available spectrum, diverse QoS requirements of various applications, and the intensifying difficulties of centralized control. A plethora of work has been carried out to address the challenges aforementioned by employing cognitive radio functionalities with self-organization features. In this article, variant aspects of selforganization paradigms in cognitive radio networks, including critical functionalities of MACand network-layer operations, are surveyed. The main contributions of this survey include introducing the fundamentals of existing cognitive radio and self-organization techniques as well as their current progress, surveying critical cognitive radio issues (including common control channel management, cooperative spectrum sensing, bioinspired spectrum sharing, network scalability and adaptive routing) as well as their self-organization features, and identifying new directions and open problems in cognitive radio networks. © 2002-2012 IEEE.

News Article | March 16, 2016
Site: cen.acs.org

Inspired by how plants transform carbon dioxide to carbohydrates in photosynthesis, researchers have developed an environmentally friendly reaction that adds the greenhouse gas to organic compounds, including biomass-derived molecules. This week at the American Chemical Society national meeting in San Diego, the team described how they used the carboxylation reaction to synthesize a monomer that could help make a substitute for polyethylene terephthalate (PET), the soda-bottle polymer that is one of the world’s largest volume plastics. They think the chemistry could open a new route for converting biomass into polymeric materials and fuels. CO reacting with carbanions and other nucleophilic carbon centers to form carboxylates isn’t a new concept. But generating nucleophiles generally requires reagents such as highly reducing metals or strong organic bases that are energy-intensive to make and difficult to recycle. “These requirements negate the environmental benefit of using CO as a substrate and limit the chemistry to low-volume targets,” noted Matthew W. Kanan of Stanford University and coworkers in a recent paper (Nature 2016, DOI: 10.1038/nature17185). In the new chemistry, Kanan and his team use carbonate to deprotonate weakly acidic C–H bonds in organic substrates. The chemists facilitate this deprotonation by running the reaction in intermediate-temperature molten salts containing cesium or potassium ions, which stabilize the deprotonated form of the substrate. The resulting nucleophilic carbon then reacts readily with CO to form carboxylates. The carbonate, which is consumed in the carboxylation, can be regenerated easily in a separate step. At a symposium in the Division of Energy & Fuels, Kanan’s graduate student Aanindeeta Banerjee described how the team used this method to carboxylate 2-furoic acid to make furan-2,5-dicarboxylic acid (FDCA). This compound can polymerize with ethylene glycol to form the possible PET substitute polyethylene furandicarboxylate (PEF). Unlike PET’s monomers, which are derived from petroleum, 2-furoic acid can be made from agricultural waste–corn- or sawdust-derived lignocellulose. Amsterdam-based Avantium is currently developing a commercial process to convert FDCA to PEF. Avantium just signed an agreement with BASF to build an FDCA plant in Belgium. The company makes FDCA from plant-based sugars. Making it instead from inedible biomass would skip difficult dehydration processes, leading to a more efficient process with lower CO emissions, Kanan says. “Once scaled up, the new route might be less wasteful—needing fewer raw materials and less energy—than the conventional industrial synthesis of FDCA,” says chemical and petroleum engineer Eric J. Beckman of the University of Pittsburgh in a commentary that accompanies the recent paper. However, “a comparison of the life-cycle impacts of the two routes will need to be performed to ensure that it is truly more sustainable.” Liang-Nian He of Nankai University, Tianjin, China, an expert on chemical fixation of CO , comments that this “inorganic carbonate-promoted C–H carboxylation opens a new way to convert inedible biomass and CO into valuable chemicals and materials.” But He points out that the process still has additional energy costs associated with forming molten salts. Kanan says his group is working on scaling up the reaction to try to commercialize it. He thinks that the carboxylation reaction could also be used to make fine chemicals and specialty chemicals in a low carbon-footprint way. Lanzatech To Make Algae Food From CO

News Article | December 9, 2015
Site: www.techtimes.com

Is there a twist in autonomous driving technology, already? Reuters is reporting that Chinese researchers have developed a car that's strictly powered by the human brain and nothing else. The news agency says that Nankai University researchers have spent two years developing the mind-controlled car, which is powered by brain signals. In the accompanying Reuters video, a driver — wearing a brain signal-reading headset of sorts and sitting in the backseat of an SUV — is able to move the vehicle forward, backwards, unlock and lock it, and come to a full stop by only using his thoughts. However, there weren't any mentions about the car being able to successfully turn. The head equipment boasts 16 sensors, which Reuters says capture the brain's electroencephalogram (EEG) signals. Those signals then work in conjunction with a developed computer program to translate the orders and control the car. Nankai University associate professor Duan Feng, who led the project, says the technology could aid Google's self-driving car and autonomous technology in the automotive space, altogether, and vice versa. "Driverless cars' further development can bring more benefits to us, since we can better realize functions relating to brain controlling with the help of the driverless cars' platform," Feng told Reuters. "In the end, cars, whether driverless or not, and machines are serving for people. Under such circumstances, people's intentions must be recognized. In our project, it makes the cars better serve human beings." That being said, there are plenty of lingering questions for the mind-controlled car concept. In particular, what if the brain gets distracted with thoughts? How would that common occurrence on the road throw the vehicle's controls off? That and how quickly would the brain-powered car be able to adjust to what other drivers inexplicably do on the road. Reuters says the concept is being further developed in collaboration with China's Great Wall Motor automaker, but currently has no plan to be put into production.

Xu H.,Nanjing Southeast University | Zheng J.,Nankai University
Macromolecular Chemistry and Physics | Year: 2010

A general approach to construct one-dimensional face-to-face alignment of porphyrin/fullerene nanowires has been developed. This system uses extended trans-dihydroxotin(IV) porphyrin and trans-dicarboxylate-substituted [60]fullerenoacetic diacid compounds. The nanowires are arranged in regular one-dimensional linear arrays with lengths in the range 50-300 nm. In the nanowires, each fullerene unit is axially coordinated to the central metal ion of a Sn(IV) porphyrin unit via Sn-carboxylate coordination and forms a face-to-face aligned structure. The synthesis and the hierarchical structure of nanowires have been investigated. They could have potential applications for photoelectronic devices, organic solar cells and so on. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Histidine functionalized multi-walled carbon nanotubes (MWCNTs-His) were synthesized for selective preconcentration of V(V). Using flow injection coupled with electrothermal atomic absorption spectrometric strategy, an on-line ultrasensitive determination of V(V) in biological and environmental samples was achieved. Statical and dynamical adsorption of V(V) with MWCNTs-His was carefully evaluated. Isotherm and kinetics of adsorption were studied and fitted in the Langmuir model. The MWCNTs-His sorbent was demonstrated to be good column packings for on-line preconcentration. All of the experimental conditions with MWCNT-His packed microcolumn for the preconcentration and determination of V(V) were investigated in detail. Including the optimal sample's pH, sample's flow rate, loading time, eluting solution and interfering ions were performed on-line, to ensure automatic determination with a high precision. With a consumption of 5.0mL sample solution and a preconcentration time of 1min, an enhancement factor of 35 with a detection limit (3s) of 9ngL -1 or 0.2nM is achieved. The sample throughput and the precision (RSD) for 11 replicate measurements of 400ngL -1 level was 28h -1 and 1.5%, respectively. The method was applied to the determination of trace V(V) in a variety of biological and environmental samples. © 2012 Elsevier B.V.

Zou C.,Nankai University | Wang Z.,Nankai University | Tsung F.,Hong Kong University of Science and Technology
Naval Research Logistics | Year: 2012

Nonparametric control charts are useful in statistical process control when there is a lack of or limited knowledge about the underlying process distribution, especially when the process measurement is multivariate. This article develops a new multivariate self-starting methodology for monitoring location parameters. It is based on adapting the multivariate spatial rank to on-line sequential monitoring. The weighted version of the rank-based test is used to formulate the charting statistic by incorporating the exponentially weighted moving average control scheme. It is robust to non-normally distributed data, easy to construct, fast to compute and also very efficient in detecting multivariate process shifts, especially small or moderate shifts which occur when the process distribution is heavy-tailed or skewed. As it avoids the need for a lengthy data-gathering step before charting and it does not require knowledge of the underlying distribution, the proposed control chart is particularly useful in start-up or short-run situations. A real-data example from white wine production processes shows that it performs quite well. © 2012 Wiley Periodicals, Inc. Naval Research Logistics 59: 91-110, 2012 Copyright © 2012 Wiley Periodicals, Inc.

Li D.,Nankai University | Liu J.,Peking Union Medical College | Chu L.,Peking Union Medical College | Yang Z.,Nankai University
Chemical Communications | Year: 2012

We report a novel mixed-component molecular hydrogel system with excellent stabilities against dilution and enzyme digestion. © 2012 The Royal Society of Chemistry.

Li G.R.,Nankai University | Zhang X.Z.,Tianjin Normal University | Song Z.,Nankai University
Annals of Physics | Year: 2014

Motivated by the physical relevance of a spectral singularity of interacting many-particle system, we explore the dynamics of two bosons as well as fermions in one-dimensional system with imaginary delta interaction strength. Based on the exact solution, it shows that the two-particle collision leads to amplitude-reduction of the wave function. For fermion pair, the amplitude-reduction depends on the spin configuration of two particles. In both cases, the residual amplitude can vanish when the relative group velocity of two single-particle Gaussian wave packets with equal width reaches the magnitude of the interaction strength, exhibiting complete particle-pair annihilation at the spectral singularity. © 2014 Elsevier Inc.

Yang N.,Beihang University | Yang N.,CAS Institute of Process Engineering | Zhai J.,Beihang University | Zhai J.,CAS Beijing National Laboratory for Molecular | And 3 more authors.
ACS Nano | Year: 2010

As a novel two-dimensional (2D) material, graphene shows great benefits in electric and material science. Compared to 1D nanomaterials, it may show more excellent properties. Here, we introduced graphene as 2D bridges into the nanocrystalline electrodes of dye-sensitized solar cells, which brought a faster electron transport and a lower recombination, together with a higher light scattering. On the basis of these advantages, the short-circuit current density was increased by 45% without sacrificing the open-circuit voltage, and the total conversion efficiency was 6.97%, which was increased by 39%, comparing with the nanocrystalline titanium dioxide photoanode, and it was also much better than the 1D nanomaterial composite electrode. © 2010 American Chemical Society.

Zou C.,Nankai University | Tsung F.,Hong Kong University of Science and Technology
Journal of Quality Technology | Year: 2010

Nonparametric or distribution-free charts are useful in statistical process control when thereis a lack of or limited knowledge about the underlying process distribution. Most existing approachesin the literature are for monitoring location parameters. They may not be effective with a change of distribution over time in many applications. This paper develops a new distribution-free control chart based on the integration of a powerful nonparametric goodness-of-fit test and the exponentially weighted moving-average (EWMA)control scheme. Benefiting from certain desirable properties of the test and the proposed charting statistic,our proposed control chart is computationally fast, convenient to use, and efficient in detecting potential shifts in location, scale, and shap Thus, it offers robust protection against variation in various underlying distributions. Numericalstudies and a real-data example show that the proposed approaches are quite effective in industrialapplications, particularly in start-up and short-run situations.

Fang L.,Nankai University | Li H.,Qinghai Normal University
Computers and Operations Research | Year: 2013

The calculation of cost efficiency requires complete and accurate information on the input prices at each decision making unit (DMU). In practice, however, exact knowledge of the relevant prices is difficult to come by, and prices may be subject to variation in the short term. To estimate the cost efficiency while taking price uncertainty into account, cone-ratio DEA models incorporating the available price information as weight restrictions can be applied. However, the literature lacks a clear explanation regarding the exact relationships between these two models. In this paper, through a duality study, we establish both the theoretical properties of these relationships and the characteristics of their efficiency solutions between cone-ratio DEA models and CE models, assuming there are imprecise price data. Based on the duality study, we also develop a new approach and design a lexicographic order algorithm to estimate the lower bounds of the cost efficiency measure. Our computational experiments indicate that the proposed models are robust and that the proposed algorithm is computationally simple. © 2012 Elsevier Ltd. All rights reserved.

Zhang K.,Nankai University | Tian S.,Nankai University | Fan E.,Albert Ludwigs University of Freiburg
Analyst | Year: 2013

Protein lysine acetylation (Kac), including histone acetylation and non-nuclear protein acetylation, is a dynamic and reversible post-translational modification for cellular regulation. The modified proteins play a key role in regulating chromatin structure, transcriptional activity and metabolic pathways, thus contributing to diverse cellular processes like transcription, cell cycle regulation, apoptosis and senescence. Therefore, targeting protein acetylation represents a potentially promising strategy for certain diseases, such as cancer. However, global identification of protein acetylation is a major bottleneck due to its dynamic property and rather low abundance. Tremendous efforts have been made to develop mass spectrometry (MS)-based proteomic technologies for this purpose from diverse cellular sources. The present review has tried to provide an overview of current strategies employed for Kac identification from histone to system-wide Kac analysis, including enrichment techniques, chromatographic separation strategies, and mass spectrometry methods. This journal is © The Royal Society of Chemistry.

Shi P.-F.,Nankai University | Shi P.-F.,Linyi Normal University | Hu H.-C.,Nankai University | Zhang Z.-Y.,Nankai University | And 2 more authors.
Chemical Communications | Year: 2015

Two cationic heterometal-organic frameworks (Eu-Zn (1·NO3 -) and Tb-Zn (2·NO3 -)) with NO3 - counter-anions in the channels are structurally and luminously characterized. Both of them can serve as highly sensitive and highly selective luminescent probes for detecting I- ions in aqueous solutions. In particular, 2·NO3 - can selectively and reversibly detect I- with a fast response time of just 10 s and an extremely low detection limit of 0.001 ppm. Mechanism studies reveal that I- is quickly oxidized to form I3 - with the help of 1·NO3 - or 2·NO3 -, leading to luminescence quenching. This represents the first report of MOF-based luminescent probes for the detection of I- in aqueous solutions. This journal is © The Royal Society of Chemistry 2015.

Du M.,Tianjin Normal University | Li C.-P.,Tianjin Normal University | Wu J.-M.,Tianjin Normal University | Guo J.-H.,Tianjin Normal University | Wang G.-C.,Nankai University
Chemical Communications | Year: 2011

This work first demonstrates that the robust [Cu2(OOCR) 4] unit can be destroyed and reconstructed in the solid state, as observed in water-induced structural interconversion of two distinct coordination polymers with 5-bromonicotinate. © 2011 The Royal Society of Chemistry.

Wu B.,Harvard University | Wu B.,Childrens Hospital | Peisley A.,Harvard University | Peisley A.,Childrens Hospital | And 9 more authors.
Cell | Year: 2013

MDA5, a viral double-stranded RNA (dsRNA) receptor, shares sequence similarity and signaling pathways with RIG-I yet plays essential functions in antiviral immunity through distinct specificity for viral RNA. Revealing the molecular basis for the functional divergence, we report here the crystal structure of MDA5 bound to dsRNA, which shows how, using the same domain architecture, MDA5 recognizes the internal duplex structure, whereas RIG-I recognizes the terminus of dsRNA. We further show that MDA5 uses direct protein-protein contacts to stack along dsRNA in a head-to-tail arrangement, and that the signaling domain (tandem CARD), which decorates the outside of the core MDA5 filament, also has an intrinsic propensity to oligomerize into an elongated structure that activates the signaling adaptor, MAVS. These data support a model in which MDA5 uses long dsRNA as a signaling platform to cooperatively assemble the core filament, which in turn promotes stochastic assembly of the tandem CARD oligomers for signaling. © 2013 Elsevier Inc.

Tian L.,Tianjin Normal University | Chen Z.,Nankai University
Inorganic Chemistry Communications | Year: 2011

Using a flexible bis-triazole ligand 1,4-bis(1,2,4-triazol-1-y1)butane (btrb), two new copper(II) compounds [Cu0.5(btrb)0.5Cl] n (1) and [Cu0.5(btrb)Cl]n (2), have been isolated. Conformations of btrb can be tuned as a result of changing the metal/ligand ratio in the reaction system, which ultimately forms two novel framework structures. 1 is a three dimensional network with CdSO4 topology, and uncommonly six-fold Cl...H-C hydrogen bonds reside in the 3D framework. 2 possesses 2D (4.4) net framewok. Triple Cl...H-C hydrogen bonds reside among the 2D layers, which link the 2D layers to lead to a 3D supramolecular architecture. For 1 and 2, elemental analysis, thermal stability and EPR spectra have been carried out, and the conformational variation of btrb also has been discussed. © 2011 Elsevier B.V. All rights reserved.

Su M.,Nankai University | Winterhof A.,Johann Radon Institute for Computational and Applied Mathematics
IEEE Transactions on Information Theory | Year: 2010

We combine the concepts of the p-periodic Legendre sequence, the (q-1)-periodic Sidelnikov sequence and the two-prime generator to introduce a new p(q-1)-periodic sequence called LegendreSidelnikov sequence. We show that this new sequence is balanced if p=q. For an arbitrary odd prime p and an arbitrary power q of an odd prime with gcd (p,q-1)=1 we determine the exact values of its (periodic) autocorrelation function and deduce an upper bound on its aperiodic autocorrelation function showing that it is small compared to its period. © 2006 IEEE.

HONG KONG, Dec. 28, 2016 /PRNewswire/ -- Jebsen Group (Jebsen), a regional leader in marketing and distribution of premium products across Greater China, has recently released its Corporate Social Responsibility (CSR) Report 2016, which marks the 8th consecutive year that Jebsen has published its annual CSR report since 2009. It summarises Jebsen's innovative and effective practices in CSR management, business partnerships, environmental conservation, staff well-being, and philanthropy in 2015 across its diverse business units. With clearly established objectives and the Group's strong commitment in CSR, the programmes have taken economic, social and environmental considerations into the company's strategic development and operations. Jebsen's business growth has been successfully achieved, while expanding its efforts in various aspects of CSR from environment conservation, staff well-being to philanthropy. With a strong focus on the betterment of society, Jebsen's invested HKD 4.5 million in CSR activities in 2015. A total of 62 philanthropic activities were organised, garnering a total attendance of 898 people/times and raising HKD 250,000 in funds. By the end of 2015, Project Morning Star, a philanthropic initiative launched by Jebsen in partnership with ORBIS in 2011, has benefited over 1.2 million ophthalmic patients in rural China in its first five-year plan thanks to donations of over RMB 5.15 million made by the Group. Due to the tremendous achievements and impact over the first five years of this programme, the next five-year plan was launched in October 2016. More than a million people are expected to benefit from it, with Jebsen donating RMB 7.4 million between 2016 and 2020. Apart from Project Morning Star, Jebsen's commitment to caring for the underprivileged is also reflected in its Life is Art programme. Launched in 2014 in Hong Kong, Shanghai, Beijing and Guangzhou, this innovative programme focuses on caring for children with autism and children from migrant families, with the Shutterbug Club, Art Jamming Class and Djembe Drum Class as some of its major activities. Through the workshops, outdoor photographic exploration, DIY album creation and mini galleries, the Shutterbug Club provides the children with the opportunity to observe the world through a different lens and learn about colour and beauty. On the other hand, by organising Djembe Drum Class, teaching music and rhythm to the autistic children and providing them the opportunity to perform at music concerts and at Jebsen's annual dinner party, the programme harnesses their creativity and increases their confidence through music. In the second half of 2015, more than 80 Jebsen employees participated in these programmes to show their love for the children. Jebsen has also continued its support to education in order to cultivate the creativity, commitment and potential of students in universities. Jebsen will donate RMB 1 million in total over 5 years, from 2015 till 2019, to Nankai University for the second phase of the Nankai- Jebsen Education Fund, awarding outstanding students and teachers achieving excellent performance. Jebsen Group also cooperated with Jilin University in 2015, marking the third year of a partnership that seeks to nurture future business leaders through the means of a summer internship programme and insightful lectures. In Hong Kong, the Jebsen Educational Foundation Scholarship has supported more than 400 students over the past 20 years at The Hong Kong University of Science and Technology. Jebsen considers the well-being of its staff to be a key priority, and recognises employees to be one of its most valuable assets. Driven by its Employer Value Proposition (EVP) - "Success Breeds Success", the Group enhanced the communication with staff by launching "Jebsen Heroes" to highlight the staff's success stories within the Group and share their achievements. In terms of staff development, the Group has developed a Career Pathing Framework and continued training programmes to support employees in their career development. In 2016, Jebsen invested HKD 3.5 million in staff training, and the total training productivity was 2,130 person-times or 14,732 hours. Advocating a positive work and life attitude, the Group organised a series of staff engagement activities to foster happier minds and healthier bodies, such as wellness seminars and exercises to guide employees to maintain their physical and mental wellness. Environmental conservation is another core area of Jebsen's CSR endeavours as it aims to strengthen sustainable development. In 2015, emissions of the Jebsen Group totalled 8,772.85 tonnes of CO2-e, with carbon intensity having decreased by 10% compared to the 2009 baseline level. Meanwhile, Jebsen continues to invest in two climate friendly projects, and purchased 7207.74 tonnes of carbon credit to achieved carbon neutrality for three years in a row. To promote green and healthy living, Jebsen offers consumers a variety of green products and services including home and building products, water purifiers, etc. Internally, Jebsen launched the "Green Office Solution", encouraging staff to reduce printing, using recyclable paper, saving water and electricity. As a Diamond Member of WWF Corporate Membership Program (CMP) in Hong Kong since 2000, Jebsen proudly participated in the Earth Hour event for the eighth consecutive year, when all non-essential lights, neon signs, billboards and computers at Jebsen locations across the region were turned off for an hour during the global event. As a company deeply rooted in the Greater China region for the past 120 years, Jebsen has been awarded seven corporate social responsibility awards in 2015 which recognise its continuous active initiatives in philanthropy, staff well-being and environment conservation. "Grounded by its core values of Commitment, Excellence, Responsibility, Recognition, and Trust, Jebsen will expand its efforts in contributing to the communities and sustain innovation and adaptiveness to market changes," said Mr Helmuth Hennig, Group Managing Director of Jebsen. For more details, please click below links to download Jebsen CSR Report 2016. Founded in 1895, Jebsen Group is a focused marketing and distribution organisation. With a long, unique established presence and deep understanding of Mainland China, Hong Kong, Macau and Taiwan, the Jebsen Group is committed to supporting our partners' needs in building market demand, generating and supporting sales, and serving as an important link to customers throughout the region.  With a broad spectrum of consumer, beverage, industrial, and motors products, Jebsen offers some 200 of the world's leading products extensive local market access with a high degree of specialisation. Outside the region, the Jebsen Group enjoys close ties with sister companies in Australia, South East Asia, Denmark, Germany, Middle East and the United States. For more information, visit www.jebsen.com and Jebsen Facebook page (facebook.com/jebsengroup), or follow us on Sina Weibo (weibo.com/jebsengroup), WeChat (id: jebsen1895) and LinkedIn (id: jebsen group).

News Article | November 28, 2016
Site: www.eurekalert.org

ITHACA, NY-- Researchers studying the viruses that affect agricultural production or human health now have a new tool for investigating where viruses have spread, on a local, national, or even global scale. VirusDetect is a free, open-source bioinformatics pipeline that can efficiently analyze small RNA (sRNA) datasets to identify both known and novel viruses. Boyce Thompson Institute (BTI) Associate Professor Zhangjun Fei and colleagues present this pipeline in a recent paper in Virology. "We choose this small RNA sequencing technology because it is a highly efficient technology for virus identification and discovery," said Fei. "VirusDetect is the first bioinformatics tool that is specifically designed to analyze this kind of data for virus detection." There are many ways to detect a virus. Traditional methods use microscopes, antibodies or molecular techniques that detect specific sequences of viral genetic material--all techniques that are not highly efficient, especially in detecting novel viruses. With newer sequencing technology, researchers can sequence viral DNA or RNA along with the host material, but this approach requires expensive, deep sequencing, and early, low-level infections can be easily missed. VirusDetect takes advantage of an antiviral defense system shared by both plants and animals called RNA interference (RNAi). When a plant or animal cell is invaded by a virus, the cell churns out numerous small RNAs that are just 21-24 nucleotides long. By sequencing these small RNAs and feeding the dataset into the VirusDetect pipeline, scientists can predict the presence of RNA viruses, DNA viruses and viroids. Fei's lab used this tool to create a Pan-African sweet potato virome, which describes all the viruses affecting sweet potatoes in multiple locations throughout Sub-Saharan Africa. With more than 1,000 field samples, the researchers couldn't process this much data manually and needed a high-throughput pipeline to identify the known and unknown viruses. "You can use this strategy to investigate virus distribution, diversity and evolution at a large scale--a continent or even global scale. You can collect samples from all over the world," said Fei. Yi Zheng, a postdoctoral scientist at BTI and Shan Gao, a former postdoctoral scientist at BTI and now a faculty member at Nankai University, China, are co-first authors on paper, with contributions from researchers at the USDA and the International Potato Center. Funding for this project came from the U.S. National Science Foundation (IOS-1110080), the USDA Specialty Crop Research Initiative (2012-01507-229756 and 2010-600-25320) and the CGIAR research program on roots, tubers and bananas. To learn more about Boyce Thompson Institute (BTI) research, visit the BTI website at http://bti. . Connect online with BTI at http://www. and http://www. . Boyce Thompson Institute is a premier life sciences research institution located in Ithaca, New York on the Cornell University campus. BTI scientists conduct investigations into fundamental plant and life sciences research with the goals of increasing food security, improving environmental sustainability in agriculture and making basic discoveries that will enhance human health. BTI employs 150 staff, with scientists from 40 countries around the world and has twice been named as one of the Best Companies in New York State. Its 15 principal investigators are leading minds in plant development, chemical ecology, microbiology and plant pathology, and have access to the institute's state-of-the-art greenhouse facilities with computerized controls and a system of integrated pest management. BTI has one of the largest concentrations of plant bioinformaticists in the U.S., with researchers who work across the entire spectrum of "omics" fields. BTI researchers consistently receive funding from NSF, NIH, USDA and DOE and publish in top tier journals. Throughout its work, BTI is committed to inspiring and educating students and to providing advanced training for the next generation of scientists. For more information, visit http://www. .

News Article | December 19, 2016
Site: www.eurekalert.org

Most women are not bothered much about the fact that they might at times share public bathrooms designated for females with transgender* women who were registered as men at birth. Men on the other hand take umbrage, and worry about the safety and privacy of the women in their lives. Such male transphobia has its roots in how men see themselves as the so-called protectors of women, says Rebecca Stones of Nankai University in China and Monash University in Australia, in an article in Springer's journal Gender Issues. Transgenderism is a controversial topic about which opinions vary greatly. It also has practical implications. In the USA, for example, so-called "bathroom bills" are being considered. These bills will have to decide whether transgender people are allowed to use facilities that are in line with their current gender identity, or should rather go to ones set aside for the sex they were registered as at birth. Some people feel that allowing the former will cross a societal boundary, and legislators cite concerns about the safety and privacy of the women and children with whom transgender females would be sharing a bathroom. Stones analyzed 1,035 comments posted by readers of 190 related online news articles to gauge public opinion about the presence of transgender females in women's only bathrooms. Men were found to be around 1.55 times more likely to express safety and privacy concerns than the very women who would be sharing facilities with transgender females. Women were much less likely to comment on news articles related to the topic, and when they did they used muted, less intense phrases. Women were much more concerned about the possible presence of so-called 'perverts' who pose as transgender females. Stones says that male transphobia is linked to the male gender role of protector. It is reflected in comments such as, "'I don't want some guy-turned-girl in a restroom while my wife is in there" and, "I have a teenage daughter and I demand that her privacy be protected from a gender-confused pervert that may walk in on her while she's in the restroom!" She theorizes that the concerns expressed by men in their online comments are also rooted in how they view transgender females. They see them not as women, but still as men who are just lying or are merely mistaken about their gender identity. "Consequently they view themselves as protecting females from these males intruding into private, female-only spaces," explains Stones. "This may be further exacerbated by a fear of deception and a belief that transgender people are mentally ill or 'sick'." *A person is described as transgender if their gender identity does not match the sex they were identified as at birth. A transgender female therefore refers to a transgender person that identifies as female, but was registered at birth as being male. Reference: Stones, R.J. (2016). Which gender is more concerned about transgender women in female bathrooms? Gender Issues. DOI 10.1007/s12147-016-9181-6

Cheng M.-M.,Nankai University | Mitra N.J.,University College London | Huang X.,Lehigh University | Torr P.H.S.,University of Oxford | Hu S.-M.,Tsinghua University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2015

Automatic estimation of salient object regions across images, without any prior assumption or knowledge of the contents of the corresponding scenes, enhances many computer vision and computer graphics applications. We introduce a regional contrast based salient object detection algorithm, which simultaneously evaluates global contrast differences and spatial weighted coherence scores. The proposed algorithm is simple, efficient, naturally multi-scale, and produces full-resolution, high-quality saliency maps. These saliency maps are further used to initialize a novel iterative version of GrabCut, namely SaliencyCut, for high quality unsupervised salient object segmentation. We extensively evaluated our algorithm using traditional salient object detection datasets, as well as a more challenging Internet image dataset. Our experimental results demonstrate that our algorithm consistently outperforms 15 existing salient object detection and segmentation methods, yielding higher precision and better recall rates. We also show that our algorithm can be used to efficiently extract salient object masks from Internet images, enabling effective sketch-based image retrieval (SBIR) via simple shape comparisons. Despite such noisy internet images, where the saliency regions are ambiguous, our saliency guided image retrieval achieves a superior retrieval rate compared with state-of-the-art SBIR methods, and additionally provides important target object region information. © 2014 IEEE.

Liang J.,University of California at Los Angeles | Li L.,University of California at Los Angeles | Tong K.,University of California at Los Angeles | Ren Z.,University of California at Los Angeles | And 4 more authors.
ACS Nano | Year: 2014

Transparent conductive electrodes with high surface conductivity, high transmittance in the visible wavelength range, and mechanical compliance are one of the major challenges in the fabrication of stretchable optoelectronic devices. We report the preparation of a transparent conductive electrode (TCE) based on a silver nanowire (AgNW) percolation network modified with graphene oxide (GO). The monatomic thickness, mechanical flexibility, and strong bonding with AgNWs enable the GO sheets to wrap around and solder the AgNW junctions and thus dramatically reduce the inter-nanowire contact resistance without heat treatment or high force pressing. The GO-soldered AgNW network has a figure-of-merit sheet resistance of 14 ohm/sq with 88% transmittance at 550 nm. Its storage stability is improved compared to a conventional high-temperature annealed AgNW network. The GO-soldered AgNW network on polyethylene terephthalate films was processed from solutions using a drawdown machine at room temperature. When bent to 4 mm radius, its sheet resistance was increased by only 2-3% after 12 000 bending cycles. GO solder can also improve the stretchability of the AgNW network. Composite TCE fabricated by inlaying a GO-soldered AgNW network in the surface layer of polyurethane acrylate films is stretchable, by greater than 100% linear strain without losing electrical conductivity. Fully stretchable white polymer light-emitting diodes (PLEDs) were fabricated for the first time, employing the stretchable TCE as both the anode and cathode. The PLED can survive after 100 stretching cycles between 0 and 40% strain and can be stretched up to 130% linear strain at room temperature. © 2014 American Chemical Society.

Liu F.J.,Nankai University | Chang T.P.,University for Information Science and Technology
Energy | Year: 2011

Knowing about wind speed distribution for a specific site is very essential step in wind resource utilizations. In this paper, a probability density function with the maximum entropy principle is derived using different algorithm from previous studies. Its validity considering various numbers of moment constraints is tested and compared with the conventional Weibull function in terms of computation accuracy. Judgment criterions include the Chi-square error, root mean square error, maximum error in cumulative distribution function as well as the relative error of wind power density between theoretical function and observation data. Wind sample data are observed at four wind farms having different weather conditions in Taiwan. The results show that the entropy quantities reveal a negative correlation with the number of constraints used, regardless of station considered. For a specific site experiencing more stable weather condition where wind regimes are not too dispersive, the conventional Weibull function may accurately describe the distribution. While for wind regimes having two humps on it, the maximum entropy distributions proposed outperform a lot the Weibull function, irrespective of wind speed or power density analyzed. For the consideration of computation burden, using four moment constraints in calculating maximum entropy parameters is recommended in wind analysis. © 2010 Elsevier Ltd.

Liu P.,University of California at Los Angeles | Xu X.,University of California at Los Angeles | Xu X.,Nankai University | Dong X.,University of California at Los Angeles | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

The mechanism and origins of Z-selectivity in olefin metathesis with chelated Ru catalysts were explored using density functional theory. The olefin approaches from the "side" position of the chelated Ru catalysts, in contrast to reactions with previous unchelated Ru catalysts that favor the bottom-bound pathway. Steric repulsions between the substituents on the olefin and the N-substituent on the N-heterocyclic carbene ligand lead to highly selective formation of the Z product. © 2012 American Chemical Society.

Huang P.-Q.,Xiamen University | Huang P.-Q.,Nankai University | Ou W.,Xiamen University | Xiao K.-J.,Xiamen University | Wang A.-E.,Xiamen University
Chemical Communications | Year: 2014

We report one-pot and chemoselective Knoevenagel-type reactions using highly stable amides and lactams as the electrophilic substrates. The method is based on the in situ activation of amide carbonyl with triflic anhydride and a subsequent reaction with carbanions generated in situ from carbonyl compounds. The amide-based method is an alternative to the versatile thioamide-based Eschenmoser sulfide contraction. © 2014 the Partner Organisations.

Qi X.,Nankai University | Guo H.,Nankai University | Li L.,Nankai University | Smith Jr. R.L.,Tohoku University
ChemSusChem | Year: 2012

Carbonaceous solid (CS) catalysts with -SO3H, -COOH, and phenolic -OH groups were prepared by incomplete hydrothermal carbonization of cellulose followed by either sulfonation with H2SO4 to give carbonaceous sulfonated solid (CSS) material or by both chemical activation with KOH and sulfonation to give activated carbonaceous sulfonated solid (a-CSS) material. The obtained carbon products (CS, CSS, and a-CSS) were amorphous; the CSS material had a small surface area (<0.5 m2 g-1) and a high -SO3H group concentration (0.953 mmol g-1), whereas the a-CSS material had a large surface area (514 m 2 g-1) and a low -SO3H group concentration (0.172 mmol g-1). The prepared materials were evaluated as catalysts for the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). Remarkably high 5-HMF yields (83 %) could be obtained efficiently (80°C and 10 min reaction time). CSS and a-CSS catalysts had similar catalytic activities and efficiencies for the conversion of fructose to 5-HMF in [BMIM][Cl]; this could be explained by the trade-off between -SO3H group concentration (high for CSS) and surface area (high for a-CSS). The cellulose-derived catalysts and ionic liquid exhibited constant activity for five successive recycles, and thus, the methods developed provide a renewable strategy for biomass conversion. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kong S.,Nankai University | Fan W.,Nankai University | Wu G.,Nankai University | Miao Z.,Nankai University | Miao Z.,Tsinghua University
Angewandte Chemie - International Edition | Year: 2012

A pinch of sugar: The new bifunctional carbohydrate/cinchonine-based thiourea 1 has been designed for the asymmetric addition reaction of α-ketophosphonates and trimethylsilyl cyanide, the product of which can be hydrolyzed to afford tertiary α-hydroxy phosphonates with excellent enantioselectivities. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cai S.,Tsinghua University | Chen C.,Tsinghua University | Sun Z.,Tsinghua University | Xi C.,Tsinghua University | Xi C.,Nankai University
Chemical Communications | Year: 2013

The CuCl catalyzed direct trifluoromethylation of sp2 C-H bonds has been realized, using the Togni reagent as the CF3 source. This reaction achieves the goal of regio-selectively converting C-H into C-CF 3 with ecological and readily available starting materials. © 2013 The Royal Society of Chemistry.

Yan X.,Tsinghua University | Chen C.,Tsinghua University | Zhou Y.,Tsinghua University | Xi C.,Tsinghua University | Xi C.,Nankai University
Organic Letters | Year: 2012

Copper-catalyzed electrophilic amination of alkenylzirconocenes is accomplished under mild reaction conditions. The reaction tolerates a wide range of functional groups and can be used to prepare some hindered enamines. © 2012 American Chemical Society.

Chang L.-X.,Nankai University | Chang L.-X.,Xinjiang Normal University | Xiong G.,Nankai University | Wang L.,Xinjiang Normal University | And 2 more authors.
Chemical Communications | Year: 2013

Two 24-nuclear lanthanide clusters, Gd24 and Dy24 were obtained and structurally characterized. Magnetic investigations reveal that Gd24 exhibits the largest entropy change (-ΔSm) of 46.12 J kg-1 K-1 for ΔH = 7 T in all reported molecular clusters, and single-molecule magnet behaviour is observed in Dy 24. © 2013 The Royal Society of Chemistry.

Ramuz M.P.,Stanford University | Vosgueritchian M.,Stanford University | Wei P.,Stanford University | Wang C.,University of Rochester | And 4 more authors.
ACS Nano | Year: 2012

Carbon allotropes possess unique and interesting physical, chemical, and electronic properties that make them attractive for next-generation electronic devices and solar cells. In this report, we describe our efforts into the fabrication of the first reported all-carbon solar cell in which all components (the anode, active layer, and cathode) are carbon based. First, we evaluate the active layer, on standard electrodes, which is composed of a bilayer of polymer sorted semiconducting single-walled carbon nanotubes and C60. This carbon-based active layer with a standard indium tin oxide anode and metallic cathode has a maximum power conversion efficiency of 0.46% under AM1.5 Sun illumination. Next, we describe our efforts in replacing the electrodes with carbon-based electrodes, to demonstrate the first all-carbon solar cell, and discuss the remaining challenges associated with this process. © 2012 American Chemical Society.

Mao X.,University of Georgia | Zhang H.,University of Georgia | Zhang H.,Nankai University | Yin Y.,University of Georgia | And 2 more authors.
Nucleic Acids Research | Year: 2012

The majority of bacterial genes are located on the leading strand, and the percentage of such genes has a large variation across different bacteria. Although some explanations have been proposed, these are at most partial explanations as they cover only small percentages of the genes and do not even consider the ones biased toward the lagging strand. We have carried out a computational study on 725 bacterial genomes, aiming to elucidate other factors that may have influenced the strand location of genes in a bacterium. Our analyses suggest that (i) genes of some functional categories such as ribosome have higher preferences to be on the leading strands; (ii) genes of some functional categories such as transcription factor have higher preferences on the lagging strands; (iii) there is a balancing force that tends to keep genes from all moving to the leading and more efficient strand and (iv) the percentage of leading-strand genes in an bacterium can be accurately explained based on the numbers of genes in the functional categories outlined in (i) and (ii), genome size and gene density, indicating that these numbers implicitly contain the information about the percentage of genes on the leading versus lagging strand in a genome. © 2012 The Author(s).

Yao K.,Tsinghua University | Chen X.,Nankai University
Journal of Intelligent and Fuzzy Systems | Year: 2013

Uncertain differential equation is a type of differential equation driven by canonical process. In this paper, a concept of α-path to uncertain differential equation is first introduced, which is a type of deterministic function that solves an associate ordinary differential equation. Then, a numerical method is designed for solving uncertain differential equations, which essentially solves each α-path and produces an inverse uncertainty distribution of the solution. To illustrate the efficiency of the numerical method, several examples are given. © 2013 - IOS Press and the authors. All rights reserved.

Xu X.,Nankai University | Xu X.,University of California at Los Angeles | Liu P.,University of California at Los Angeles | Lesser A.,Stanford University | And 3 more authors.
Journal of the American Chemical Society | Year: 2012

The first theoretical study on the effects of ligands on the mechanism, reactivities, and regioselectivities of Rh(I)-catalyzed (5 + 2) cycloadditions of vinylcyclopropanes (VCPs) and alkynes has been performed using density functional theory (DFT) calculations. Highly efficient and selective intermolecular (5 + 2) cycloadditions of VCPs and alkynes have been achieved recently using two novel rhodium catalysts, [Rh(dnCOT)] +SbF 6 - and [Rh(COD)] +SbF 6 -, which provide superior reactivities and regioselectivities relative to that of the previously reported [Rh(CO) 2Cl] 2 catalyst. Computationally, the high reactivities of the dnCOT and COD ligands are attributed to the steric repulsions that destabilize the Rh-product complex, the catalyst resting state in the catalytic cycle. The regioselectivities of reactions with various alkynes and different Rh catalysts are investigated, and a predictive model is provided that describes substrate-substrate and ligand-substrate steric repulsions, electronic effects, and noncovalent π/π and C-H/π interactions. In the reactions with dnCOT or COD ligands, the first new C-C bond is formed proximal to the bulky substituent on the alkyne to avoid ligand-substrate steric repulsions. This regioselectivity is reversed either by employing the smaller [Rh(CO) 2Cl] 2 catalyst to diminish the ligand-substrate repulsions or by using aryl alkynes, for which the ligand-substrate interactions become stabilizing due to π/π and C-H/π dispersion interactions. Electron-withdrawing groups on the alkyne prefer to be proximal to the first new C-C bond to maximize metal-substrate back-bonding interactions. These steric, electronic, and dispersion effects can all be utilized in designing new ligands to provide regiochemical control over product formation with high selectivities. The computational studies reveal the potential of employing the dnCOT family of ligands to achieve unique regiochemical control due to the steric influences and dispersion interactions associated with the rigid aryl substituents on the ligand. © 2012 American Chemical Society.

Cao W.,Tsinghua University | Zhang X.,Nankai University | Miao X.,Nankai University | Yang Z.,Nankai University | Xu H.,Tsinghua University
Angewandte Chemie - International Edition | Year: 2013

An overwhelming response: The exposure of a supramolecular hydrogel based on a diselenide-containing polymer and a peptide amphiphile containing a drug moiety to γ radiation led to a gel-sol transition owing to the oxidative cleavage of diselenide bonds in the polymer main chain (see picture). The hydrogel can also act as a UV-mediated drug self-delivery system and suggests a new avenue for combined radio- and chemotherapy. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Huang P.,Sun Yat Sen University | Yuan F.-F.,Nankai University
Physics of the Dark Universe | Year: 2016

Following the spirit of the equivalence principle, we take a step further to recognize the free fall of the observer as a method to eliminate causes that would lead the perceived vacuum to change its original state. Thus, it is expected that the vacuum should be in a rigid Minkowski state or be uniformly expanding. By carefully investigating the impact on measurement caused by the expansion, we clarify the exact meaning of the uniformly expanding vacuum and find that this proposal may be able to explain the current observations of an accelerating universe. © 2016 Elsevier B.V.

Qi X.,Nankai University | Watanabe M.,Tohoku University | Aida T.M.,Tohoku University | Smith R.L.,Tohoku University
Bioresource Technology | Year: 2012

A method for converting glucose into 5-hydroxymethylfurfural (5-HMF) without using chromium-containing catalysts was developed. The method uses ionic liquid-water mixtures with a ZrO 2 catalyst. Addition of a certain amount of water (10-50wt.%) into the 1,3-dialkylimidazolium chloride ionic liquid promoted the formation of 5-HMF from glucose compared with that in either pure water or in the pure ionic liquid. A 5-HMF yield of 53% was obtained within 10min at 200°C in a 50:50w/w% 1-hexyl-3-methyl imidazolium chloride-water mixture in the presence of ZrO 2. The 1,3-dialkylimidazolium ionic liquids having Cl - or HSO4- anions were effective for promoting 5-HMF formation. Addition of protic solvents such as methanol and ethanol to the ionic liquid had a similar synergistic effect as water and promoted fructose and 5-HMF formation. The results reported in this work can be extended to other fields, where the ratio of ionic liquid and protic solvent can be adjusted to promote the desired reactions. © 2012 Elsevier Ltd.

Kehl T.,German Cancer Research Center | Tan J.,Nankai University | Materniak M.,National Veterinary Research Institute
Viruses | Year: 2013

Within the field of retrovirus, our knowledge of foamy viruses (FV) is still limited. Their unique replication strategy and mechanism of viral persistency needs further research to gain understanding of the virus-host interactions, especially in the light of the recent findings suggesting their ancient origin and long co-evolution with their nonhuman hosts. Unquestionably, the most studied member is the primate/prototype foamy virus (PFV) which was originally isolated from a human (designated as human foamy virus, HFV), but later identified as chimpanzee origin; phylogenetic analysis clearly places it among other Old World primates. Additionally, the study of non-simian animal FVs can contribute to a deeper understanding of FV-host interactions and development of other animal models. The review aims at highlighting areas of special interest regarding the structure, biology, virus-host interactions and interspecies transmission potential of primate as well as non-primate foamy viruses for gaining new insights into FV biology. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Zhou H.,Nankai University | Zhou H.,Tsinghua University | Sun Y.,CAS Institute of Biophysics | Guo Y.,Nankai University | Lou Z.,Tsinghua University
Trends in Microbiology | Year: 2013

Negative-sense single-stranded RNA viruses (NSRVs) possess a ribonucleoprotein (RNP) complex composed of viral polymerase and genomic RNA surrounded by viral nucleoprotein. The RNP facilitates virus replication, transcription, and assembly. To date, a large body of structural work, through crystallography and electron microscopy (EM) analysis, has been performed to aid understanding the molecular mechanism of RNP formation in NSRVs, and provides great potential for the discovery of antiviral agents targeting viral RNP formation. © 2013 Elsevier Ltd.

Guo H.,Nankai University | Qi X.,Nankai University | Li L.,Nankai University | Smith R.L.,Tohoku University
Bioresource Technology | Year: 2012

A sulfonated carbon material was prepared by incomplete hydrothermal carbonization of glucose followed by sulfonation. The carbon material contained -SO 3H, -COOH, and phenolic -OH groups, and exhibited high catalytic performance for the hydrolysis of cellulose. A total reducing sugar (TRS) yield of 72.7% was obtained in ionic liquid 1-butyl-3-methyl imidazolium chloride at 110°C in 240min reaction time. The effect of water on the hydrolysis of cellulose in the catalytic system was studied. A water content of less than 2% in the ionic liquid promoted the formation of TRS, whereas a water content of greater than 2% lead to a decrease in TRS. The sulfonated carbon material catalyst was demonstrated to be stable for five cycles with minimal loss in catalytic activity. The use of an ionic liquid with functionalized carbon catalyst derived from glucose provides a green and efficient process for cellulose conversion. © 2012 Elsevier Ltd.

Wang H.,Nankai University | Shi Y.,Nankai University | Wang L.,Tianjin Key Laboratory of Molecular Drug Research | Yang Z.,Nankai University
Chemical Society Reviews | Year: 2013

Protein-based hydrogels are promising materials for tissue engineering and drug delivery due to the unique properties of proteins such as perfect polydispersity, exact control over monomer sequence, ability to fine-tune molecular-level biochemical interactions, etc. This tutorial review summarizes recent progress on the preparation of protein-based hydrogels and their applications. Typically, we introduce two strategies of covalent and non-covalent ones for the preparation of hydrogels. Hydrogels prepared by the covalent strategy are stable and can respond to the conformational change of proteins. They can be applied for cells encapsulation, screening of drug molecules and heavy metals, etc. Hydrogels formed by non-covalent interactions are injectable physical hydrogels. The simple mixing preparation strategy and fast gelation kinetics guarantee the homogeneous encapsulation of cells and therapeutic agents within them. Therefore, they have been widely applied for the delivery of bioactive components, regenerative medicine, etc. The challenges that remained in this field are also summarized in this paper. We envision that rationally designed protein-based hydrogels will have broad applications in many areas including controlled delivery, tissue engineering, drug screening, etc. © 2013 The Royal Society of Chemistry.

Wang F.,Tsinghua University | Cai S.,Tsinghua University | Wang Z.,Tsinghua University | Xi C.,Nankai University
Organic Letters | Year: 2011

An efficient strategy for the synthesis of a variety of 2-mercaptobenzothiazole derivatives has been developed. The reaction proceeded from o-haloaniline derivatives and carbon disulfide via a tandem reaction in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to afford the corresponding 2-mercaptobenzothiazole derivatives in good to excellent yields. © 2011 American Chemical Society.

Li Y.-M.,Tsinghua University | Li Y.-M.,Hefei University of Technology | Li Y.-T.,Tsinghua University | Pan M.,Tsinghua University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2014

Sortase-mediated hydrazinolysis of proteins with hydrazine or its derivatives was developed for the production of recombinant protein hydrazides. This process provides an alternative approach for protein semisynthesis through the use of recombinant protein hydrazides as thioester surrogates. It also provides an alternative method for C-terminal modification of proteins with functional units as well as for the preparation of C-to-C fusion proteins. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Meng X.-H.,Nankai University | Meng X.-H.,CAS Institute of Theoretical Physics | Wang Y.-B.,Nankai University
European Physical Journal C | Year: 2011

Generalized from the so-called teleparallel gravity, which is exactly equivalent to general relativity, f(T) gravity has been proposed as an alternative gravity model to account for the dark energy phenomena. In this letter we prove that the external vacuum gravitational field for a spherically symmetric distribution of source matter in the f(T) gravity framework must be static. The conclusion is independent of the radial distribution and spherically symmetric motion of the source matter, that is, whether it is in motion or static. As a consequence, the Birkhoff's theorem is valid in the general nonsingular f(T) theory at the un-perturbative level. We also discuss its application in the de Sitter spacetime evolution phase as preferred by present dark energy observations. © 2011 Springer-Verlag / Società Italiana di Fisica.

Xu X.,Nankai University | Xu X.,University of California at Los Angeles | Liu P.,University of California at Los Angeles | Shu X.-Z.,University of Wisconsin - Madison | And 2 more authors.
Journal of the American Chemical Society | Year: 2013

The mechanism of Rh-catalyzed (5+2) cycloadditions of 3-acyloxy-1,4-enyne (ACE) and alkynes is investigated using density functional theory calculations. The catalytic cycle involves 1,2-acyloxy migration, alkyne insertion, and reductive elimination to form the cycloheptatriene product. In contrast to the (5+2) cycloadditions with vinylcyclopropanes (VCPs), in which alkyne inserts into a rhodium-allyl bond, alkyne insertion into a Rh-C(sp2) bond is preferred. The 1,2-acyloxy migration is found to be the rate-determining step of the catalytic cycle. The electron-rich p-dimethylaminobenzoate substrate promotes 1,2-acyloxy migration and significantly increases the reactivity. In the regioselectivity-determining alkyne insertion step, the alkyne substituent prefers to be distal to the forming C-C bond and thus distal to the OAc group in the product. © 2013 American Chemical Society.

Chen W.,University of Puerto Rico at San Juan | Li Y.,Nankai University | Yu G.,Jilin University | Li C.-Z.,Florida International University | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

The intriguing electronic and magnetic properties of fully and partially hydrogenated boron nitride nanoribbons (BNNRs) were investigated by means of first-principles computations. Independent of ribbon width, fully hydrogenated armchair BNNRs are nonmagnetic semiconductors, while the zigzag counterparts are magnetic and metallic. The partially hydrogenated zigzag BNNRs (using hydrogenated BNNRs and pristine BNNRs as building units) exhibit diverse electronic and magnetic properties: they are nonmagnetic semiconductors when the percentage of hydrogenated BNNR blocks is minor, while a semiconductor→ half-metal→metal transition occurs, accompanied by a nonmagnetic→ magnetic transfer, when the hydrogenated part is dominant. Although the half-metallic property is not robust when the hydrogenation ratio is large, this behavior is sustained for partially hydrogenated zigzag BNNRs with a smaller degree of hydrogenation. Thus, controlling the hydrogenation ratio can precisely modulate the electronic and magnetic properties of zigzag BNNRs, which endows BN nanomaterials many potential applications in the novel integrated functional nanodevices. © 2010 American Chemical Society.

Xu W.,Huazhong University of Science and Technology | Wang J.,Nankai University | Meng X.-H.,Nankai University | Meng X.-H.,CAS Institute of Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We revisit the entropy product, entropy sum and other thermodynamic relations of charged and rotating black holes. Based on these relations, we derive the entropy (area) bound for both event horizon and Cauchy horizon. We establish these results for variant class of 4-dimensional charged and rotating black holes in Einstein(-Maxwell) gravity and higher derivative gravity. We also generalize the discussion to black holes with NUT charge. The validity of this formula, which seems to be universal for black holes with two horizons, gives further clue on the crucial role that the thermodynamic relations of multi-horizons play in black hole thermodynamics and understanding the entropy at the microscopic level. © 2015 The Authors.

Yuan F.-F.,Nankai University | Huang P.,Sun Yat Sen University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry. © 2015 The Authors.

Hou Y.-L.,Nankai University | Hou Y.-L.,Kaili University | Xu H.,Nankai University | Cheng R.-R.,Nankai University | Zhao B.,Nankai University
Chemical Communications | Year: 2015

Two novel 3D frameworks were synthesized, and further nanosized to form nanospheres. Studies revealed that 2 is the first MOF-based luminescent sensor for detecting cyclohexane, and this is also the first time that quick regeneration, high sensitivity, high yield, and easy nanocrystallization of MOF-based luminescent sensors have been simultaneously realized. © 2015 The Royal Society of Chemistry.

Zheng Q.,Tsinghua University | Hua R.,Tsinghua University | Hua R.,Nankai University
Tetrahedron Letters | Year: 2010

1,3-Butadiynes underwent inter- and intramolecular double hydroamination with primary amines in the presence of CuCl at 100°C to afford 1,2,5-trisubsituted pyrroles in good to high yields. © 2010 Elsevier Ltd. All rights reserved.

Gao G.,Nankai University | Falconer R.A.,University of Cardiff | Lin B.,University of Cardiff | Lin B.,Tsinghua University
Water Research | Year: 2011

Faecal bacteria exist in both free-living and attached forms in surface waters. The deposition of sediments can take faecal bacteria out of the water column and to the bed. The sediments can subsequently be re-suspended into the water column, which can then lead to the re-suspension of the faecal bacteria of the attached form back into the water column, where it may desorb from the sediments. Therefore, the fate and transport of faecal bacteria is highly related to the governing sediment transport processes, particularly where these processes are significant. However, little attempt has been made to model such processes in terms of predicting the impact of the sediment fluxes on faecal bacteria levels. Details are given of the refinement of a numerical model of faecal bacteria transport, where the sediment transport processes are significant. This model is based on the model DIVAST (Depth Integrated Velocities And Solute Transport). Analytical solutions for steady and uniform flow conditions were derived and used to test the sediment-bacteria interaction model. After testing the sediment-bacteria interaction model favourably against known results, the model was then set up for idealised case studies to investigate the effects of sediment on bacteria concentrations in the water column. Finally the model was applied to a simplified artificial flooding study to investigate the impact of suspended sediment fluxes on the corresponding bacteria transport processes. The model predictions have proved to be encouraging, with the results being compared to field measurements. © 2011 Elsevier Ltd.

Meng X.,Nankai University | Meng X.,CAS Institute of Theoretical Physics | Du X.,Nankai University | Du X.,Lanzhou University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

In the generalized Einstein-aether theories by taking a special form of the Lagrangian density of aether field, the possibility of Einstein-aether theory as an alternative to dark energy model is discussed in detail, that is, taking a special aether field as a dark energy candidate. We compute the joint statistic constraints on this special model's parameters by using the recent type Ia supernovae (SNe Ia) data, the Cosmic Microwave Background (CMB) shift parameter data, and the Baryonic Acoustic Oscillations (BAOs) data traced by the Sloan Digital Sky Survey (SDSS). Furthermore, we analyze other constrains from the Observational Hubble parameter Data (OHD). The comparison with the standard cosmological model (cosmological constant Λ Cold Dark Matter (ΛCDM) model) is clearly shown with new features; also we comment on an interesting relation between the coupling constant M in this model and the possible existence of a special accelerating scale in the MOdified Newtonian Dynamics (MOND) model initially given by Milgrom with the hope for interpreting the galaxy rotation curves without introducing mysterious dark matter. © 2012.

Lin G.-J.,Xiamen University | Zheng X.,Xiamen University | Huang P.-Q.,Xiamen University | Huang P.-Q.,Nankai University
Chemical Communications | Year: 2011

An efficient and highly diastereoselective method for the construction of the hydroxylated tropane skeleton is described. The method features a new intramolecular reductive coupling reaction of N-acyl N,O-acetal with aldehyde, cooperatively mediated by BF 3·OEt 2 and SmI 2. On the basis of this method, a new enantioselective total synthesis of (-)-Bao Gong Teng A has been accomplished. © 2011 The Royal Society of Chemistry.

Chang X.,Jilin University | Wang Z.-Q.,Nankai University | Wang Z.-Q.,Utah State University
Nonlinearity | Year: 2013

This paper focuses on the following scalar field equation involving a fractional Laplacian:(δ) αu = g(u) in ℝN, where N ≥ 2, α ∈ (0, 1), (?δ) α stands for the fractional Laplacian. Using some minimax arguments, we obtain a positive ground state under the general BerestyckiLions type assumptions. © 2013 IOP Publishing Ltd & London Mathematical Society.

Li P.,The Key Laboratory of Molecular Microbiology and Technology | Wang L.,Nankai University | Feng L.,Tianjin Key Laboratory of Microbial Functional Genomics
Journal of Bacteriology | Year: 2013

The cold-tolerant bacterium Pusillimonas sp. strain T7-7 is able to utilize diesel oils (C5 to C30 alkanes) as a sole carbon and energy source. In the present study, bioinformatics, proteomics, and real-time reverse transcriptase PCR approaches were used to identify the alkane hydroxylation system present in this bacterium. This system is composed of a Rieske-type monooxygenase, a ferredoxin, and an NADH-dependent reductase. The function of the monooxygenase, which consists of one large (46.711 kDa) and one small (15.355 kDa) subunit, was further studied using in vitro biochemical analysis and in vivo heterologous functional complementation tests. The purified large subunit of the monooxygenase was able to oxidize alkanes ranging from pentane (C5) to tetracosane (C24) using NADH as a cofactor, with greatest activity on the C15 substrate. The large subunit also showed activity on several alkane derivatives, including nitromethane and methane sulfonic acid, but it did not act on any aromatic hydrocarbons. The optimal reaction condition of the large subunit is pH 7.5 at 30°C. Fe2+ can enhance the activity of the enzyme evidently. This is the first time that an alkane monooxygenase system belonging to the Rieske non-heme iron oxygenase family has been identified in a bacterium. © 2013, American Society for Microbiology.

Ji S.,Shandong University of Technology | Li X.,Nankai University | Shi Y.,Nankai University
Match | Year: 2013

The energy of a graph G is equal to the sum of the absolute values of the eigenvalues of G. Recently, Gutman and Wagner proposed the concept of the matching energy (ME) and pointed out that the chemical applications of ME go back to the 1970s. Let G be a simple graph of order n and μ1, μ2,., μn be the roots of its matching polynomial. The matching energy is defined as the sum ∑i=0 n |μi|. In this paper, we characterize the graphs with the extremal matching energy among all bicyclic graphs, and completely determine the graphs with the minimal and maximal matching energy in bicyclic graphs.

Zhao P.,Tsinghua University | Yan X.,Tsinghua University | Yin H.,Tsinghua University | Xi C.,Tsinghua University | Xi C.,Nankai University
Organic Letters | Year: 2014

The reaction of arylisothiocyanate, alkyltriflate, and alkynes leads to variously substituted quinolines in high yields. The reaction undergoes alkyltriflate-triggered domino electrophilic activation and avoids the use of a transition-metal catalyst. A variety of functional groups are tolerated in the quinoline ring. © 2014 American Chemical Society.

Yan X.,Tsinghua University | Xi C.,Tsinghua University | Xi C.,Nankai University
Accounts of Chemical Research | Year: 2015

Conspectus Metalloles are derivatives of cyclopentadiene in hich the methylene unit is replaced by a heteroatom, such as S, Se, Te, N, P, As, Sb, Bi, Si, Ge, Sn, B, Al, Ga, and so on. Many metallole derivatives have been idely used as photovoltaic cells, organic light emitting diodes (OLEDs), chemical sensors, electrochromic devices, microelectronic actuators, and organic field effect transistors (OFETs). In the meantime, many of them shoed promising biological actives. Due to the similarity to cyclopentadiene, the anionic forms of metalloles ere also idely explored in coordination chemistry. As a result, development of a general method for the formation of metalloles from available starting materials is highly desired.In this Account, e outline formation of various p-block element metalloles from zirconacyclopentadienes. The zirconacyclopentadienes can be easily prepared from to molecules of alkynes and a lo-valent zirconocene species Cp2Zr(II) (Cp = cyclopentadienyl). Fagan and Nugent first reported the formation of main group metalloles from zirconacyclopentadiene, hich provided a versatile approach for the construction of metalloles, especially for the formation of metalloles in heavier p-block elements. To further expand the substrate scope, a number of stepise conversions ere developed, hich involve 1,4-dimetallo- or dihalo-1,3-butadiene as intermediates from zirconacyclopentadienes.Here, four processes are classified based on direct and indirect conversion of zirconacyclopentadienes into metalloles. Direct reaction of zirconacyclopentadienes ith element halides afforded heterocycles of main group elements, hich provided a versatile method for the synthesis of metalloles. Nonetheless, the reaction scope as restricted to heavier p-block elements such as S, Se, P, As, Sb, Bi, Ge, Sn, Ga, and In. And these reactions usually suffered lo yields and long reaction time. Transmetalation of zirconacyclopentadiene ith copper chloride greatly enriched the zirconacyclopentadiene chemistry. The synthesis of stannoles and pyrroles from zirconacyclopentadienes has been developed in the presence of CuCl. The direct reaction of the zirconacyclopentadienes ith SiCl4 or R2SiCl2 does not give the desired silacyclopendadiene derivatives, even in the presence of CuCl. It can be circumvented by using dilithiated dienes from diiododienes, hich are easily prepared by the iodination of zirconacyclopentadienes using CuCl as an additive. Finally, an umpolung strategy, reaction of electrophilic 1,4-diiodo-1,3-butadiene ith nucleophilic amine or sulfide reagents, as successfully used in the formation of pyrroles and thiophenes. © 2015 American Chemical Society.

Chen X.,Nankai University | Liu Y.,Tsinghua University | Ralescu D.A.,University of Cincinnati
Fuzzy Optimization and Decision Making | Year: 2013

This paper presents an uncertain stock model with periodic dividends based on uncertainty theory. Some option pricing formulae related to the proposed model are investigated and several numerical examples are discussed to illustrate the related formula. © 2012 Springer Science+Business Media New York.

Li M.,CAS Institute of Theoretical Physics | Miaob R.-X.,The Interdisciplinary Center | Miao Y.-G.,Nankai University
Journal of High Energy Physics | Year: 2011

We investigate the Hamiltonian formulation of f(T) gravity and find that there are five degrees of freedom. The six first class constraints corresponding to the local Lorentz transformation in Teleparallel gravity become second class constraints in f(T) gravity, which leads to the appearance of three extra degrees of freedom and the violation of the local Lorentz invariance in f(T) gravity. In general, there are D-1 extra degrees of freedom for f(T) gravity in D dimensions, and this implies that the extra degrees of freedom correspond to one massive vector field or one massless vector field with one scalar field. © SISSA 2011.

Miao R.-X.,The Interdisciplinary Center | Li M.,CAS Institute of Theoretical Physics | Miao Y.-G.,Nankai University
Journal of Cosmology and Astroparticle Physics | Year: 2011

We prove that, in general, the first law of black hole thermodynamics, δQ = TδS, is violated in f(T) gravity. As a result, it is possible that there exists entropy production, which implies that the black hole thermodynamics can be in non-equilibrium even in the static spacetime. This feature is very different from that of f(R) or that of other higher derivative gravity theories. We find that the violation of first law results from the lack of local Lorentz invariance in f(T) gravity. By investigating two examples, we note that f′′(0) should be negative in order to avoid the naked singularities and superluminal motion of light. When f′′(T) is small, the entropy of black holes in f(T) gravity is approximatively equal to f′(T)/4 A. © 2011 IOP Publishing Ltd and SISSA.

Dong H.,Nankai University | Wang Y.,Nankai University | Meng X.,Nankai University | Meng X.,CAS Institute of Theoretical Physics
European Physical Journal C | Year: 2012

f(T) theory, a generally modified teleparallel gravity, has been proposed as an alternative gravity model to account for the dark energy phenomena. Following our previous work [Xin-he Meng and Ying-bin Wang, Eur. Phys. J. (2011), arXiv:1107. 0629v1], we prove that Birkhoff's theorem holds in a more general context, specifically with the off diagonal tetrad case, in this communication letter. Then, we discuss, respectively, the results of the external vacuum and internal gravitational field in the f(T) gravity framework, as well as the extended meaning of this theorem. We also investigate the validity of Birkhoff's theorem in the frame of f(T) gravity via a conformal transformation by regarding the Brans-Dicke-like scalar as effective matter, and study the equivalence between both Einstein frame and Jordan frame. © 2012 Springer-Verlag / Società Italiana di Fisica.

Yan T.,Nankai University | Wang Y.,CAS Institute of Theoretical Physics | Knox C.,University of Utah
Journal of Physical Chemistry B | Year: 2010

An electronically polarizable model, based on the AMBER nonpolarizable model, has been developed for the ionic liquid (IL) 1-ethyl-3-methyl-imidazolium nitrate (EMIM+/NO3 -). Molecular dynamics simulation studies were then performed with both the polarizable and nonpolarizable models. These studies suggest EMIM+ cations have a strong tendency to pack with their neighboring imidazolium rings nearly parallel to each other, bridged by hydrogen bonds to NO3 - anions. Polarization has two key effects, (1) additional charge-dipole and dipole-dipole interactions enhance short-range electrostatic interactions and (2) screening reduces long-range electrostatic interactions. As a result, the polarizable model exhibited enhanced hydrogen bonding compared to the nonpolarizable model, while the latter retained more ordered long-range spatial correlations than the former. Though EMIM+ has a very short nonpolar ethyl tail group, spatial heterogeneity, previously observed with long-chain ILs, was observed in this system and has been quantified using the heterogeneity order parameter. The polarizable model was slightly more heterogeneous than the nonpolarizable model. The enhanced spatial heterogeneity of the polarizable model is again attributed to the stronger short-range electrostatic interactions, which "push" the nonpolar tails away from the polar heads, leading to more aggregation and a strongly altered ionic packing pattern around NO 3 - as observed by a different anion-anion center-of-mass partial radial distribution function g- (r). Interestingly, both models seemed to "remember" the crystal structure even at temperatures significantly higher (∼90 K higher) than the melting point (311 K). Along with the results on the dynamical properties reported in the accompanying paper, the current study demonstrates that electronic polarizability is significant in ionic liquid systems. © 2010 American Chemical Society.

Yan T.,Nankai University | Wang Y.,CAS Institute of Theoretical Physics | Knox C.,University of Utah
Journal of Physical Chemistry B | Year: 2010

An electronically polarizable model has been developed for the ionic liquid (IL) 1-ethyl-3-methyl-imidazolium nitrate (EMIM+/NO3 -) (Yan et al. J. Phys. Chem. B DOI:10.1021/jp9089112). Molecular dynamics simulations were then performed with both the polarizable and nonpolarizable models. Both models exhibited certain properties that are similar to a supercooled liquid behavior even though the simulations were run at 400 K (89 K above the melting point of EMIM+/NO3 -). The ionic mean-squared displacement and transverse current correlation function of both models were well represented by a memory function with a fast Gaussian initial relaxation followed by the two-step exponential functions for β- and α- structural relaxations. Another feature shared by both models is the dynamic heterogeneity, which highlights the complex dynamic behavior of ILs. Apart from the overall slow dynamics, the relaxation of the H-atoms attached to the methyl group demonstrates a "free rotor" type of motion. Also, the ethyl group shows the fastest overall relaxation, due to the weak electrostatic interactions on it. Such flexibility enhances the entropic effect and thus favors the liquid state at room temperature. For the dynamical properties reported in this paper, the polarizable model consistently exhibited faster relaxations (including translational and reorientational motions), higher self-diffusion and ionic conductivity, and lower shear viscosity than the nonpolarizable model. The faster relaxations of the polarizable model result from attenuated long-range electrostatic interactions caused by enhanced screening from the polarization effect. Therefore, simulations based on the polarizable model may be analogous to simulations with the nonpolarizable model at higher temperatures. On the other hand, the enhanced intermolecular interactions for the polarizable model at short-range due to the additional charge-dipole and dipole-dipole interactions result in a red shift of the intramolecular C-H stretch spectrum and a higher degree of ion association, leading to a spectrum with enhanced conductivity across the whole frequency range. The vibrational motion associated with the intermolecular hydrogen bonding is highly IR active, highlighting the importance of hydrogen bond dynamics in ILs. © 2010 American Chemical Society.

The present invention relates to -carboline, dihydro--carboline and tetrahydro--carboline alkaloid derivatives (I), a method for preparing the same and their use as fungicide, insecticide and in preventing and treating plant virus infections. For the meaning of each group in formula (I), see the description. The -carboline, dihydro--carboline and tetrahydro--carboline alkaloid derivatives of the present invention show a particularly pronounced anti-plant virus activity, and also have fungicidal and insecticidal activities.

The present invention relates to -carboline, dihydro--carboline and tetrahydro--carboline alkaloid derivatives (I) and a method for preparing same and the use in the aspects of preventing and treating plant viruses, fungicides and insecticides. For the meaning of each group in formula (I) see the description. The -carboline, dihydro--carboline and tetrahydro--carboline alkaloid derivatives of the present invention show a particularly ourstanding anti-plant virus activity, and also have fungicidal and insecticidal activities.

News Article | November 21, 2016
Site: www.eurekalert.org

HOUSTON -- (Nov. 21, 2016) -- Rice University engineer Mason Tomson has been elected a fellow of the American Association for the Advancement of Science (AAAS), the largest general scientific society in the world and publisher of the journal Science. He is one of 391 new fellows announced today by AAAS. This honor is awarded to AAAS members by their peers on the basis of their scientifically or socially distinguished efforts to advance science or its applications. Tomson, a professor of civil and environmental engineering, was elevated to this rank for his "research and education on aqueous chemical adsorption, desorption and transport important in environmental chemistry of arsenic, hydrocarbons, and mineral scale prediction and inhibition." A member of the Rice faculty since 1977, Tomson specializes in research on the fate and transport of organic and inorganic chemicals in the environment. In the late 1970s, Tomson's research group was among the first to prove that groundwater could be readily contaminated by organic chemicals from the surface. His group helped develop and demonstrate the concepts of enhanced chemical transport in groundwater and of resistant desorption of chemicals from soils and sediments. These concepts have recently been demonstrated to apply to fullerene and activated carbon nanoparticles. Tomson is also an expert on the mechanisms of mineral scale formation and control. He has decades of experience in researching the processes involved in scale formation -- processes that govern the formation of mineral deposits in household water pipes, industrial cooling towers and even kidney stones. He developed one of the fundamental theories that scientists use to explain how chemicals called scale inhibitors prevent mineral formation. Scale inhibitors are widely used in nearly all arenas of industrial water treatment and in virtually all oil and gas wells in the world. Tomson is leading an effort to establish a joint program on sustainable environmental development between Rice University and Nankai University in Tianjin, China. He also heads the Brine Chemistry Consortium, an industrial group that focuses on applied research and development on scale and corrosion inhibitors in natural gas wells. Tomson and the other new AAAS fellows will be listed in the Nov. 25 issue of Science and will be presented with a certificate and pin Feb. 18 during the 2017 AAAS annual meeting in Boston. Founded in 1848, AAAS is a nonprofit organization whose mission is to "advance science and serve society" through initiatives in science policy, international programs, science education and public engagement. A high-resolution IMAGE is available for download at:http://news.

Kong X.,Nankai University | Huang Y.,Center for Nanoscale Science and Technology
Journal of Nanoscience and Nanotechnology | Year: 2014

This paper reviews the up-to-date research about the applications of graphene and its related materials in the field of mass spectrometry (MS). Due to its large surface area, delocalized π-electrons, thermal conductivity, stability and rich interaction chemistry, graphene has been widely used in MS-based analytical chemistry. Graphene-based materials were applied as very effective matrixes or surfaces for many kinds of organic molecules in laser desorption/ionization (LDI) MS analysis. Many advantages of this novel matrix have been proved, which included: low interference ions from matrix itself, good reproducibility, high salt tolerance and so on. The unique properties of graphene also make it a superior sorbent used in solid-phase extraction (SPE). Further development of online SPE methods based on graphene coupling directly with LDI-MS, GC-MS and LC-MS greatly simplifies the MS-based analytical procedure for complex samples and makes the corresponding high-throughput and automatic analysis performable. Their applications as a platform in proteolysis for the rapid identification of proteins have been also developed. In addition, graphene was found to be a unique precursor for the generation of large-sized carbon cluster anions in the gas phase. Finally, the possible challenges and future perspectives in their applications in MS are discussed too. Copyright © 2014 American Scientific Publishers All rights reserved.

Li Y.,Nankai University | Belkin N.J.,Rutgers University
Journal of the American Society for Information Science and Technology | Year: 2010

This study explores the relationships between work task and interactive information search behavior. Work task was conceptualized based on a faceted classification of task. An experiment was conducted with six work-task types and simulated work-task situations assigned to 24 participants. The results indicate that users present different behavior patterns to approach useful information for different work tasks:They select information systems to search based on the work tasks at hand, different work tasks motivate different types of search tasks, and different facets controlled in the study play different roles in shaping users' interactive information search behavior. The results provide empirical evidence to support the view that work tasks and search tasks play different roles in a user's interaction with information systems and that work task should be considered as a multifaceted variable. The findings provide a possibility to make predictions of a user's information search behavior from his or her work task, and vice versa. Thus, this study sheds light on task-based information seeking and search, and has implications in adaptive information retrieval (IR) and personalization of IR. © 2010 ASIS&T.

Yang L.,Nankai University | Zhu L.,Nankai University | Liu Z.,Chinese Research Academy of Environmental Sciences
Chemosphere | Year: 2011

The concentrations of four perfluorinated sulfonate acids (PFSAs) and 10 perfluorinated carboxylate acids (PFCAs) were measured in water and sediment samples from Liao River and Taihu Lake, China. In the water samples from Taihu Lake, PFOA and PFOS were the most detected perfluorinated compounds (PFCs); in Liao River, PFHxS was the predominant PFC followed by PFOA, while PFOS was only detected in two of the samples. This suggests that different PFC products are used in the two regions. PFOS and PFOA in both watersheds are at similar level as in the rivers of Japan, but significantly lower than in Great Lakes. The contributions of PFOS and long chain PFCAs in sediments were much higher than in water samples of both watersheds, indicating preferential partition of these PFCs in sediment. The concentrations of PFOS and PFOA were three orders of magnitude of lower than that of polycyclic aromatic hydrocarbons in the same sediments. The average sediment-water partition coefficients (log. Koc) of PFHxS, PFOS and PFOA were determined to be 2.16, 2.88 and 2.28 respectively. © 2011 Elsevier Ltd.

Peng S.,Central China Normal University | Wang Z.-Q.,Nankai University | Wang Z.-Q.,Utah State University
Archive for Rational Mechanics and Analysis | Year: 2013

We consider the following nonlinear Schrödinger system in ℝ3, where P(r) and Q(r) are positive radial potentials, μ > 0, ν > 0 and β ∈ ℝ is a coupling constant. This type of system arises, in particular, in models in Bose-Einstein condensates theory. We examine the effect of nonlinear coupling on the solution structure. In the repulsive case, we construct an unbounded sequence of non-radial positive vector solutions of segregated type, and in the attractive case we construct an unbounded sequence of non-radial positive vector solutions of synchronized type. Depending upon the system being repulsive or attractive, our results exhibit distinct characteristic features of vector solutions. © 2012 Springer-Verlag Berlin Heidelberg.

Plotnik Y.,Technion - Israel Institute of Technology | Rechtsman M.C.,Technion - Israel Institute of Technology | Song D.,Nankai University | Heinrich M.,Friedrich - Schiller University of Jena | And 9 more authors.
Nature Materials | Year: 2014

Graphene, a two-dimensional honeycomb lattice of carbon atoms, has been attracting much interest in recent years. Electrons therein behave as massless relativistic particles, giving rise to strikingly unconventional phenomena. Graphene edge states are essential for understanding the electronic properties of this material. However, the coarse or impure nature of the graphene edges hampers the ability to directly probe the edge states. Perhaps the best example is given by the edge states on the bearded edge that have never been observed - because such an edge is unstable in graphene. Here, we use the optical equivalent of graphene - a photonic honeycomb lattice - to study the edge states and their properties. We directly image the edge states on both the zigzag and bearded edges of this photonic graphene, measure their dispersion properties, and most importantly, find a new type of edge state: one residing on the bearded edge that has never been predicted or observed. This edge state lies near the Van Hove singularity in the edge band structure and can be classified as a Tamm-like state lacking any surface defect. The mechanism underlying its formation may counterintuitively appear in other crystalline systems. © 2014 Macmillan Publishers Limited.

Rechtsman M.C.,Solid State Institute | Plotnik Y.,Solid State Institute | Zeuner J.M.,Friedrich - Schiller University of Jena | Song D.,Nankai University | And 4 more authors.
Physical Review Letters | Year: 2013

We experimentally demonstrate a topological transition of classical light in "photonic graphene": an array of waveguides arranged in the honeycomb geometry. As the system is uniaxially strained (compressed), the two unique Dirac points (present in the spectrum of conventional graphene) merge and annihilate each other, and a band gap forms. As a result, edge states are created on the zigzag edge and destroyed on the bearded edge. These results are applicable for any 2D honeycomb-type structure, from carbon-based graphene to photonic lattices and crystals. © 2013 American Physical Society.

Zhang Y.,Chinese Research Academy of Environmental Sciences | Guo C.-S.,Chinese Research Academy of Environmental Sciences | Xu J.,Chinese Research Academy of Environmental Sciences | Tian Y.-Z.,Nankai University | And 2 more authors.
Water Research | Year: 2012

In this work, three receptor models (Principal Component Analysis-Multiple Linear Regression (PCA-MLR) model, Unmix model and Positive Matrix Factorization (PMF) model) were employed to investigate potential source apportionment of PAHs in sediments from Taihu Lake, China. A total of 15 priority PAHs in 29 sediments from Taihu Lake were measured, with ∑PAHs (sum of 15 PAHs) concentrations ranging from 209 to 1003 ng g -1 dw. Source apportionment results derived from three different models were similar, indicating that the highest contribution to ∑PAHs was from vehicular emission (53.6-54.3%), followed by coal combustion (23.8-28.8%) and wood combustion (11.9-16.0%). The contribution of mixed wood and coal combustion source identified by PCA-MLR was 41.3%. For the first time the risk assessment for each identified source category was quantitatively calculated by combining the BaP equivalents (BaPE) values with estimated source contributions. The results showed that vehicular emission posed the highest toxic risk, with BaPE values of 26.9-31.5 ng g -1 dw, and the BaPE values for coal combustion and wood combustion were 6.56-15.6 ng g -1 dw and 2.94-6.11 ng g -1 dw, respectively. The distributions of contribution and BaPE for each identified source category were studied as well, and showed similar trends among the sampling sites, for each source category. © 2012 Elsevier Ltd.

Chen F.,Nankai University | Gao J.,University of Florida | Zhou Q.,Nankai University
Environmental Pollution | Year: 2012

The objective of this study was to assess potential toxic effects of simulated urban runoff on Carassius auratus using oxidative stress biomarkers. The activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of malondialdehyde (MDA) in the liver of C. auratus were analyzed after a 7-, 14- and 21-day exposure to simulated urban runoff containing galaxolide (HHCB) and cadmium (Cd). The results showed that the activity of antioxidant enzymes and the content of MDA increased significantly exposed to the simulated urban runoff containing HHCB alone or mixture of HHCB and Cd. The activity of the investigated enzymes and the content of MDA then returned to the blank level over a longer period of exposure. The oxidative stress could be obviously caused in the liver of C. auratus under the experimental conditions. This could provide useful information for toxic risk assessment of urban runoff. © 2011 Elsevier Ltd. All rights reserved.

Bai C.,Nankai University | Guo L.,Rutgers University | Ni X.,Nankai University
Communications in Mathematical Physics | Year: 2010

We generalize the classical study of (generalized) Lax pairs, the related O-operators and the (modified) classical Yang-Baxter equation by introducing the concepts of nonabelian generalized Lax pairs, extended O-operators and the extended classical Yang-Baxter equation. We study in this context the nonabelian generalized r-matrix ansatz and the related double Lie algebra structures. Relationship between extended O-operators and the extended classical Yang-Baxter equation is established, especially for self-dual Lie algebras. This relationship allows us to obtain an explicit description of the Manin triples for a new class of Lie bialgebras. Furthermore, we show that a natural structure of PostLie algebra is behind O-operators and fits in a setup of the triple Lie algebra that produces self-dual nonabelian generalized Lax pairs. © 2010 Springer-Verlag.

Yu L.-Q.,Nankai University | Yu L.-Q.,Hebei University | Yan X.-P.,Nankai University
Chemical Communications | Year: 2013

Here we report a covalent bonding approach to fabricate a robust metal-organic framework ZIF-90 coating for solid-phase microextraction. The ZIF-90 bonded fiber exhibits high enhancement factors, wide linearity, excellent reproducibility, and good lifetime for the studied polar endocrine disruptors. © 2013 The Royal Society of Chemistry.

Su L.,Nankai University | Su L.,Zhejiang University of Technology | Zhong Y.,Nankai University | Zhou Z.,Nankai University
Journal of Materials Chemistry A | Year: 2013

The conversion reaction mechanism has widely been accepted in interpreting and evaluating the lithium storage capability of transition metal oxides (MOs). However, this mechanism cannot well explain the phenomenon of the extra capacity which exists in almost all MO materials and attracts much attention. Up to now, the extra capacity phenomenon has generally been ascribed to the reversible conversion of polymeric gel-like films. However, the essential role of metal nanoparticles in this process has not been systematically investigated. To further illustrate the role of metal nanoparticles for the extra capacity, Fe3O4@C and Fe@C monodispersed hierarchical core-shell microspheres were designed and adopted as the case study. Naturally Fe 3O4@C composites exhibited a large Li storage capacity beyond its theoretical value. However, Fe@C microspheres, which are usually regarded to be inert for lithium storage, still presented a certain electrochemical capacity. Fe nanoparticles might serve as electrocatalysts for the reversible conversion of some components of solid electrolyte interface films, and bring extra capacity to Fe3O4 and electrochemical capacity to Fe. This study can enlighten us for the exploiting of advanced active materials and electrolytes for Li ion batteries, and new energy storage devices. © 2013 The Royal Society of Chemistry.

Wang K.-R.,Nankai University | Wang K.-R.,Hebei University | Guo D.-S.,Nankai University | Jiang B.-P.,Nankai University | Liu Y.,Nankai University
Chemical Communications | Year: 2012

A supramolecular self-assembly has been constructed by perylene-bridged bis(β-cyclodextrin)s with water-soluble porphyrin through hydrophobic interactions, showing strong excitonic coupling interactions between perylene backbones and included porphyrins. © 2012 The Royal Society of Chemistry.

Huang Y.-F.,Nankai University | Huang Y.-F.,National Engineering Technology Research Center for Preservation of Agricultural Products | Wang Y.-F.,Tianjin University of Science and Technology | Yan X.-P.,Nankai University
Environmental Science and Technology | Year: 2010

Interest in magnetic nanoparticles for capturing bacteria arises from a variety of attributes, including the similar size of nanoparticles, magnetic behavior, and attached biomolecules such as proteins and nucleotide probes. Here we report the application of amine-functionalized magnetic nanoparticles (AF-MNPs) for rapid and efficient capture and removal of bacterial pathogens. The AF-MNPs are used without the need for any further modifications with affinity biomolecules. The positive charges on the surface of AF-MNPs can promote strong electrostatic interaction with negatively charged sites on the surface of bacterial pathogens to exhibit efficient adsorptive ability. The hydrophobic interaction between the pendant propyl group of the amine functionality and the bacteria also plays a supplementary role. The amine groups on the surface of the magnetic nanoparticle are robust and inexpensive ligands to ensure a high binding affinity to at least eight different species of Gram-positive and Gram-negative bacteria. The amount of AF-MNPs, pH of phosphate buffer solution, and ionic strength are crucial in mediating fast and effective interactions between AF-MNPs and bacteria. The AF-MNPs allow rapid removal of bacteria from water samples, food matrixes, and a urine sample with efficiency from 88.5% to 99.1%. Though amino group offers less specificity/selectivity than biomolecules such as antibodies, AF-MNPs are attractive for capturing a wide range of bacteria. © 2010 American Chemical Society.

Accendatech and Nankai University | Date: 2013-07-15

The present invention relates to the uses of sesquiterpene lactone compounds and their derivatives in preparing drugs. It belongs to the field of drug technology, specifically relates to the uses of the compounds of Formula (I) in preparing the drugs, especially the uses in preparing the drugs to treat rheumatoid arthritis and treat cancers through inhibiting cancer stem cells.

Nankai University and Accendatech | Date: 2011-04-14

The present invention provides a compound of formula (I)

Accendatech and Nankai University | Date: 2013-02-27

The present invention provides micheliolide derivatives or salts thereof of formula (I)

News Article | November 9, 2015
Site: cen.acs.org

Two massive blasts at a hazardous chemical storage warehouse in Tianjin’s harbor killed at least 50 people and injured hundreds of others on Aug. 12. Victims were primarily firefighters and employees of cargo handling firms operating in the Chinese harbor. Beijing Daily Group, a media group based in Beijing, reported that the first explosion had a force equivalent to 3 tons of TNT. The second blast, far larger, represented the equivalent of 21 tons of TNT. Chinese state media reported that windows were shattered on buildings miles away from the accident. Chinese TV news showed images of huge plumes of flames shooting into the sky. The accident occurred in Binhai New Area at the company Ruihai Logistics, a freight handler that according to state media reports is authorized to manage dangerous goods. Authorities took in several of the company’s employees for questioning. The firm’s website became inaccessible after the blasts. With a population of 15 million people, Tianjin is one of four cities directly managed by China’s national government. In a statement, Tianjin’s government said China’s President Xi Jinping had taken control of the situation. Xi issued several directives, notably ordering that the fire be rapidly put down and that those responsible be severely punished. In an account on the Chinese website Weibo, Tianjin’s fire department said it deployed 143 engines and 1,000 firefighters to control the fire, but that it didn’t know the nature of the chemicals involved in the disaster. According to Chinese media, several firefighters died and others are unaccounted for. Tianjin is home to some of China’s top universities, including Nankai University and Tianjin University (TJU). Jay Siegel, dean of the School of Pharmaceutical Science & Technology at TJU, tells C&EN that students and staff at his school are safe because the school is in the center of Tianjin, more than 40 miles away from the port. Binhai is, however, located about 8 miles from the Tianjin Economic-Technological Development Area, home to numerous pharmaceutical and chemical companies. Among international firms with operations in the area, according to TEDA, are Dow Chemical, Eastman Chemical, Cabot Corp., AkzoNobel, and GlaxoSmithKline. Vanessa Craigie, communications manager for Cabot, says the company’s plant is in an industrial park 20 km from the chemical warehouse and was not impacted by the explosion. “To our knowledge, none of our employees or their families were affected by the explosion,” she tells C&EN. “We are continuing to check in on each employee individually to confirm.”

Zhang P.,Nankai University | Li B.,Nankai University | Wang Q.,Colorado State University
Macromolecules | Year: 2011

Using fast lattice Monte Carlo (FLMC) simulations both in a canonical ensemble and with Wang-Landau-transition-matrix sampling, we have studied a model system of homopolymer brushes in an implicit, good solvent. Direct comparisons of the simulation results with those from the corresponding lattice self-consistent field (LSCF) theory, both of which are based on the same Hamiltonian (thus without any parameter-fitting between them), unambiguously and quantitatively reveal the fluctuations and correlations in the system. We have examined in detail how the chain number density C and the interaction strength N/κ (where N is the number of segments on a chain and κ is inversely proportional to the second virial coefficient characterizing the solvent quality) affect both the brush structures and thermodynamics. For our model system, the LSCF theory is exact in both limits of C → ∞ and N/κ → ∞, where there are no fluctuations or correlations. At finite C and N/κ > 0, the segmental density profile in the direction perpendicular to the grafting substrate obtained from FLMC simulations is flatter than the LSCF prediction, and the profile differences are smaller in higher dimensions. The free-end density from FLMC simulations is also lower than the LSCF prediction well inside the brush. The LSCF theory underestimates the free energy but overestimates the entropy per chain, and underestimates the internal energy per chain at small N/κ but overestimates it at large N/κ. At large C, FLMC results approach LSCF predictions at a rate of 1/C in most cases. © 2011 American Chemical Society.

Teng H.-L.,Wuhan University | Yao L.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Journal of the American Chemical Society | Year: 2014

An unprecedented Cu(I)-catalyzed asymmetric [6 + 3] cycloaddition of tropone with azomethine ylides was reported, which performs well over a broad scope of substrates and offers a unique and facile access to the synthetically useful bridged azabicyclo[4.3.1]decadiene derivatives in good yields with high levels of diastereoselectivities and enantioselectivities under mild conditions. © 2014 American Chemical Society.

Mu L.,Agro Environmental Protection Institute | Gao Y.,Nankai University | Hu X.,Nankai University
Biomaterials | Year: 2015

Graphene oxide (GO) has been employed in various fields, and its ecological and health risks have attracted much attention. A small and inexpensive biomolecule, l-cysteine, was covalently immobilized onto GO to form l-cysteine-GO (CysGO) as a thio-functionalized nanosheet of 1.4nm in thickness. Both the d-spacing and crystallinity of CysGO were observed to be lower than those of GO, whereas the D and G peaks remained similar to those of GO. CysGO exhibited remarkable uptake invivo: no tissue defects, malformation, death or significant hatching delay were observed in zebrafish embryos. Significant DNA damage, decreased Na+/K+-ATPase activity and decreased mitochondrial membrane potential were not observed for CysGO. As a nonspecific activity linked to nanotoxicology, the unpaired electron spinning intensity of CysGO was approximately two orders of magnitude lower than that of GO. Oxygen microsensor analysis showed that the hypoxic and normoxic environments resulting from the presence of GO and CysGO envelopment, respectively, contributed to the difference in biocompatibility. CysGO also protected embryos from arsenic poisoning. Thus, CysGO has the advantageous properties of GO, exhibits excellent biocompatibility, acts as a breathable coating and antidote, and is suitable for various applications. © 2015 Elsevier Ltd.

Yoo H.,Incheon National University | Kim J.,Incheon National University | Zhang L.,Nankai University
Current Applied Physics | Year: 2012

We made Cu 2ZnSnS 4 (CZTS) thin films by sulfurization of Cu/Sn/Cu/Zn metallic films. Sulfurizations were carried out under different thermal annealing conditions, where maximum temperatures were 440 °C (LT-CZTS) and 550°C (HT-CZTS). For LT-CZTS films, secondary phases such as SnS 2 and Cu 2-xS were observed, whereas for HT-CZTS films secondary impurities were not detected. Chemical composition of LT-CZTS film was observed to be very non-uniform. Highly Sn-rich and Zn-rich regions were found on the film surface of LT-CZTS. However, averaged chemical composition for larger area was close to stoichiometry. The HT-CZTS film showed homogeneous structural and chemical composition features. But, for HT-CZTS film, the Sn composition was observed to be decreased, which was due to the Sn-loss. By UV-Visible spectroscopy, optical band gaps of LT- and HT-CZTS films were measured to be ∼1.33 eV and ∼1.42 eV, respectively. The band gap of LT-CZTS film was also observed to be smaller by photoluminescence measurement. The depressed band gap of LT-CZTS film may be ascribed to some defects and low band gap impurities such as Cu 2SnS 3 and Cu 2-xS in the LT-CZTS film. © 2011 Elsevier B.V. All rights reserved.

Fang X.,Wuhan University | Li Q.-H.,Wuhan University | Tao H.-Y.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Advanced Synthesis and Catalysis | Year: 2013

The first organocatalytic asymmetric addition of thiols to trifluoromethylaldimine for the construction of chiral trifluoromethylated N,S-acetals has been achieved in high yields (up to 99%) and excellent enantioselectivities (up to 95% ee) with 1 mol% of a bifunctional organocatalyst. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li Q.-H.,Wuhan University | Wei L.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Journal of the American Chemical Society | Year: 2014

Conjugated cyclic trienes without nonbenzenoid aromatic characteristic were successfully employed as fine-tunable dipolarophiles in the Cu(I)-catalyzed asymmetric azomethine ylide-involved 1,3-dipolar [3 + 6] cycloaddition for the first time, affording a variety of bridged heterocycles bearing piperidine moiety in good yield with exclusive regioselectivity and excellent stereoselectivity. 2-Acyl group is the key factor that determines the annulation preferentially through [3 + 6]-pathway, while 2-ester group modulates the annulation through [3 + 2]-pathway. © 2014 American Chemical Society.

Qu H.,Shandong Institute of Business and Technology | Cao S.,Nankai University
PLoS ONE | Year: 2015

For a given graph G, ε(v) and deg(v) denote the eccentricity and the degree of the vertex v in G, respectively. The adjacent eccentric distance sum index of a graph G is defined as ξsv(G) = ∑vεV(G)ε(v)D(v) deg(v), where D(v) = ∑uεV(G)d(u, v) is the sum of all distances from the vertex v. In this paper we derive some bounds for the adjacent eccentric distance sum index in terms of some graph parameters, such as independence number, covering number, vertex connectivity, chromatic number, diameter and some other graph topological indices. Copyright: © 2015 Qu, Cao. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Fang X.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Chemical Communications | Year: 2014

Organocatalysis has proven to be one of the most rapidly developing and competitive research areas in asymmetric catalysis since 2000, and has become a third branch besides biocatalysis and transition metal catalysis. In this feature article, recent progress from our research group on asymmetric organocatalysis, focusing on fine-tunable amine-thiourea catalysis, is described. Design of novel bifunctional amine-thiourea organocatalysts based upon the synergistic activation strategy via multiple hydrogen bonds and their applications in asymmetric C-C, C-N, and C-S bond-forming reactions under mild conditions are discussed in detail. The most attractive feature of the newly designed fine-tunable amine-thiourea catalysts is the incorporation of multiple hydrogen bonding donors and stereogenic centers. This journal is © The Royal Society of Chemistry.

Fang X.,Wuhan University | Li J.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Organic Letters | Year: 2013

A highly efficient organocatalytic asymmetric SMA reaction of hexafluoroisopropyl α,β-unsaturated esters has been developed. Introducing electron-withdrawing hexafluoroisopropyl ester is crucial to enhancing the electrophilicity of unsaturated esters as SMA acceptors. The catalytic system performs well over a broad scope of α,β-unsaturated esters and diversified thiols and provides facile access to (R)-thiazesim in a one-pot protocol. © 2013 American Chemical Society.

Tong M.-C.,Wuhan University | Chen X.,Wuhan University | Tao H.-Y.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Angewandte Chemie - International Edition | Year: 2013

Ylides at a crossing: An unprecedented 1,3-dipolar cycloaddition (cross-cycloaddition) between two different ylides (see scheme) was realized by using the chiral CuI/tBu-Phosferrox complex as the catalyst under mild reaction conditions. This catalytic system provides an expeditious approach to the construction of highly functionalized 1,2,4-triazinane derivatives in good yields with excellent diastereoselectivities and enantioselectivities. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

He Z.-L.,Wuhan University | Teng H.-L.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Angewandte Chemie - International Edition | Year: 2013

As easy as π: Fulvenes serve as 6π dipolarophiles in the title reaction in the presence of the chiral CuI/(S)-L complex. The present system provides a unique and straightforward access to enantioenriched, highly functionalized piperidine derivatives in good yields and excellent diastereoselectivities and enantioselectivities. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

He Y.,Hubei University | Yan X.,Nankai University
Science China Chemistry | Year: 2011

Mn-doped ZnS quantum dots /methyl violet nanohybrids were explored to develop a novel room temperature phosphorescence (RTP) sensor for the detection of DNA. Methyl violet (MV) as the electron acceptors was adsorbed on the surface of the quantum dots (QDs) to quench the RTP of the Mn-doped ZnS QDs through an electron-transfer process under excitation. The addition of DNA recovered the RTP signal of the Mn-doped ZnS QDs due to the binding of MV with DNA and the removal of MV from the surface of the Mn-doped ZnS QDs. Under the optimal conditions, the enhanced RTP intensity of the Mn-doped ZnS QDs/MV nanohybrids linearly increased with the concentration of DNA from 0.08 to 12 mg L -1 with the detection limit of 33.6 μg L-1. The relative standard deviation for eleven replicate detections of the reagent blank was 3.7%. The developed method was applied to the detection of DNA in spiked urine samples with recoveries of 96%-103% without interference from nonspecific fluorescence. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.

Zhao J.,Tianjin Polytechnic University | Wei J.,PLA Military Transportation University | Li Y.,Nankai University
International Journal of Production Economics | Year: 2014

Pricing decisions for two substitutable products in a supply chain with one common retailer and two competitive manufacturers are considered in this paper. The purpose of this paper is to analyze the effects of the two manufacturers different competitive strategies and the channel members different power structures on the optimal pricing decisions. One centralized pricing model and seven decentralized pricing models are developed, and the corresponding analytical equilibrium solutions are obtained by using game-theoretic approach. Finally, numerical studies are presented to illustrate the effectiveness of the theoretical results, and to gain additional managerial insights. © 2014 Elsevier B.V. All rights reserved.

Xu S.,Xi'an Jiaotong University | He Z.,Nankai University
RSC Advances | Year: 2013

Organic synthetic reactions mediated by tertiary phosphines have attracted much attention in the organic chemistry community in the past two decades. These reactions can be divided into two categories: phosphine-catalyzed and stoichiometric phosphine-mediated transformations. While the phosphine-catalyzed reactions mechanistically rely on the unique properties of tertiary phosphines such as excellent nucleophilicity and good leaving group ability, the stoichiometric transformations are usually driven by nucleophilicity and strong oxyphilicity of tertiary phosphines. Since tertiary phosphines represent an important class of versatile chemical reagents in organic synthesis, stoichiometric phosphine-mediated reactions have recently demonstrated their uniqueness and high efficiency in organic synthesis, particularly with respect to the construction of carbon-carbon and carbon-heteroatom bonds, and therefore have stimulated much research interest. In this review, recent advances in stoichiometric phosphine-mediated reactions primarily including olefinations and annulations are summarized. © 2013 The Royal Society of Chemistry.

Dong X.-Q.,Wuhan University | Fang X.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Organic Letters | Year: 2011

The first asymmetric sulfa-Michael addition of thiols to 4,4,4-trifluorocrotonates for the construction of a stereogenic center bearing a unique trifluoromethyl group and a sulfur atom has been achieved in high yields and excellent enantioselectivities with a 1 mol % bifunctional organocatalyst. Subsequent transformation led to the expedient preparation of enantioenriched thiochroman-4-one and the key intermediate of the potent inhibitor of MMP-3, (R)-γ-trifluoromethyl γ-sulfone hydroxamate. © 2011 American Chemical Society.

Xue Z.-Y.,Wuhan University | Li Q.-H.,Wuhan University | Tao H.-Y.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Journal of the American Chemical Society | Year: 2011

A novel catalytic asymmetric Michael addition of azomethine ylide with β-substituted alkylidene bisphosphates was realized in the presence of a chiral copper(I)/TF-BiphamPhos complex. The present system provides a unique and facile access to enantioenriched unnatural α-amino acid derivatives containing gem-bisphosphonates (gem-BPs) in high yields with excellent diastereoselectivities and enantioselectivities. Subsequent transformations lead to the expedient preparation of biologically active unnatural α-amino acid derivatives containing BPs and bisphosphonic acids without loss of diastereo- and enantiomeric excess. © 2011 American Chemical Society.

Tong M.-C.,Wuhan University | Chen X.,Wuhan University | Li J.,Wuhan University | Huang R.,Wuhan University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

An unprecedented catalytic asymmetric inverse-electron-demand aza-Diels-Alder reaction of indoles with in situ formed azoalkenes is reported. A diverse set of [2,3]-fused indoline heterocycles were achieved in generally good yields (up to 97 %) with high regioselectivity and diastereoselectivity (>20:1 d.r.), and with excellent enantioselectivity (up to 99 % ee). In(verse) demand: The unprecedented catalytic asymmetric inverse-electron-demand aza-Diels-Alder reaction of indoles with in situ formed azoalkenes is reported. A diverse set of [2,3]-fused indoline heterocycles were produced in generally good yields with high regioselectivity and diastereoselectivity, and with excellent enantioselectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

He Z.,Wuhan University | Liu T.,Wuhan University | Tao H.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Organic Letters | Year: 2012

Facile access to enantioenriched isoindolines bearing a quaternary stereogenic center and a tertiary stereogenic center was successfully developed via highly efficient Cu(I)/(S,Rp)-PPFOMe-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide with quinone derivatives followed by silica-gel-promoted aromatization in a one-pot reaction protocol. The present catalytic system exhibited high diastereoselectivity, excellent enantioselectivity, and a broad substrate scope under mild conditions. © 2012 American Chemical Society.

Wei J.,PLA Military Transportation University | Govindan K.,University of Southern Denmark | Li Y.,Nankai University | Zhao J.,Tianjin Polytechnic University
Computers and Operations Research | Year: 2015

The optimal decision problem of a closed-loop supply chain with symmetric and asymmetric information structures is considered using game theory in this paper. The paper aims to explore how the manufacturer and the retailer make their own decisions about wholesale price, retail price, and collection rate under symmetric and asymmetric information conditions. Four game models are established, which allow one to examine the strategies of each firm and explore the role of the manufacturer and the retailer in four different game scenarios under symmetric and asymmetric information structures. The optimal strategies in closed form are given under the decision scenarios with symmetric information; moreover, the first order conditions that the optimal retail price, optimal wholesale price, and optimal collection rate satisfy are given under the decision scenarios with asymmetric information. The results obtained under symmetric and asymmetric information conditions and some key model parameters used in this paper are analyzed using a numerical approach by which some managerial analysis are given. © 2013 Elsevier Ltd. All rights reserved.

Wang B.,Institute of Materials Research and Engineering of Singapore | Zhang X.,Wuhan University | Yuan X.,Nankai University | Teng J.,Institute of Materials Research and Engineering of Singapore
Applied Physics Letters | Year: 2012

In this letter, we theoretically investigate the coupling of far-infrared surface plasmon polaritons (SPPs) between spatially separated graphene sheets. By using the finite-difference frequency-domain method, we numerically illustrate the SPP propagation and modulation in the graphene sheets. The coupling of SPPs is employed to design zero insertion loss optical splitters, 1 × 2 digital optical spatial switches, and ultra-compact Mach-Zehnder interferometers with the arm length far below the diffraction limit. The study provides an effective way in designing graphene based high-speed and ultra-compact optoelectronic devices. © 2012 American Institute of Physics.

Gao X.-P.,Nankai University | Yang H.-X.,Wuhan University
Energy and Environmental Science | Year: 2010

The need for high energy density batteries becomes increasingly important for the development of new and clean energy technologies, such as electric vehicles and electrical storage from wind and solar power. The search for new energetic materials of primary and secondary batteries with higher energy density has been highlighted in recent years. This review surveys recent advances in the research field of high energy density electrode materials with focus on multi-electron reaction chemistry of light-weight elements and compounds. In the first section, we briefly introduce the basic strategies for enhancement of the energy density of primary batteries based on multi-electron reactions. The following sections present overviews of typical electrode materials with multi-electron chemistry and their secondary battery applications in aqueous and non-aqueous electrolytes. Finally, the challenges and ongoing research strategies of these novel electrode materials and battery systems for high density energy storage and conversion are discussed. © 2010 The Royal Society of Chemistry.

Liu K.,Wuhan University | Teng H.-L.,Wuhan University | Wang C.-J.,Wuhan University | Wang C.-J.,Nankai University
Organic Letters | Year: 2014

An unprecedented catalytic tandem formal [4 + 3] cycloaddition/decarboxylation/isomerization of methyl coumalate and imine esters is successfully developed. This tandem reaction only requires Et3N as the mild base affording a series of highly functionalized seven-membered heterocyclic azepine derivatives in good yields with excellent regioselectivities. © 2014 American Chemical Society.

Feng Z.,Rti International | Liu C.,Brown University | Guan X.,Nankai University | Mor V.,Brown University
Health Affairs | Year: 2012

In China, formal long-term care services for the large aging population have increased to meet escalating demands as demographic shifts and socioeconomic changes have eroded traditional elder care. We analyze China's evolving long-term care landscape and trace major government policies and private-sector initiatives shaping it. Although home and community-based services remain spotty, institutional care is booming with little regulatory oversight. Chinese policy makers face mounting challenges overseeing the rapidly growing residential care sector, given the tension arising from policy inducements to further institutional growth, a weak regulatory framework, and the lack of enforcement capacity.We recommend addressing the following pressing policy issues: building a balanced system of services and avoiding an "institutional bias" that promotes rapid growth of elder care institutions over home or community-based care; strengthening regulatory oversight and quality assurance with information systems; and prioritizing education and training initiatives to grow a professionalized long-term care workforce. © 2012 Project HOPE- The People-to-People Health Foundation, Inc.

Xin W.,Chinese PLA General Hospital | Wei W.,Nankai University | Li X.-Y.,Chinese PLA General Hospital
American Journal of Clinical Nutrition | Year: 2013

Background: The effects of fish oil on heart rate variability in humans remain unclear. Objective: A meta-analysis of randomized controlled trials was performed to investigate the influence of fish oil on heart rate variability. Design: Human intervention studies were identified by systematic search of PubMed, Embase, The Cochrane Library, and references of related reviews and studies. A random-effects model was applied to estimate the pooled results. Results: Fifteen studies were included. Results of the meta-analysis showed that the SD of normal-to-normal interval [standardized mean difference (SMD) = 0.10, P = 0.35] and square of successive differences (SMD = 0.05, P = 0.35), 2 of the time-domain parameters of heart rate variability, were not significantly influenced by fish-oil supplementation. For the frequency-domain parameters, the high-frequency power (HF), a surrogate of vagal function, was significantly increased by fish-oil supplementation (SMD = 0.30, P = 0.005), the low-frequency power (LF) was not significantly affected (SMD = 0.03, P = 0.79), and the ratio of LF to HF (LF/HF) showed a trend of reduction (SMD = 20.22, P = 0.08). The trend for a treatment effect on LF/HF became significant at P = 0.01 when the 2 studies with a dose <1000 mg/d were omitted. Subgroup analyses according to predefined study characteristics showed no significant results. Conclusion: Short-term fish-oil supplementation may favorably influence the frequency domain of heart rate variability, as indicated by an enhanced vagal tone, which may be an important mechanism underlying the antiarrhythmic and other clinical effects of fish oil. © 2013 American Society for Nutrition.

Ding R.,Nankai University | Wang L.,University of Delaware | Zhu B.,Nankai University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

Neutralino can be the dark matter candidate in the gauge-mediated supersymmetry breaking models if the conformal sequestered mechanism is assumed in the hidden sector. In this paper, we study this mechanism by using the current experimental results after the run I of LHC and LUX. By adding new Yukawa couplings between the messenger fields and Higgs fields, we find that this mechanism can predict a neutralino dark matter with correct relic density and a Higgs boson with mass around 125 GeV. All our survived points have some common features. First, the Higgs sector falls into the decoupling limit. So the properties of the light Higgs boson are similar to the predictions of the Standard Model one. Second, the correct EWSB hints a relatively small μ-term, which makes the lightest neutralino lighter than the lightest stau. So a bino-higgsino dark matter with correct relic density can be achieved. And the relatively small μ-term results in a small fine-tuning. Finally, this bino-higgsino dark matter can pass all current bounds, including both spin-independent and spin-dependent direct searches. The spin-independent cross section of our points can be examined by further experiments. © 2014 The Authors.

Ou C.,Guangzhou University | Zhang J.,Guangzhou University | Zhang X.,Nankai University | Yang Z.,Nankai University | Chen M.,Southern Medical University
Chemical Communications | Year: 2013

We report a 'super-gelator' of a short peptide capped with phenothiazine acetic acid. © 2013 The Royal Society of Chemistry.

Kang M.,University of Hong Kong | Kang M.,Nankai University | Feng T.,University of Hong Kong | Wang H.-T.,Nankai University | And 2 more authors.
Optics Express | Year: 2012

We propose an ultra-Thin metamaterial constructed by an ensemble of the same type of anisotropic aperture antennas with phase discontinuity for wave front manipulation across the metamaterial. A circularly polarized light is completely converted to the cross-polarized light which can either be bent or focused tightly near the diffraction limit. It depends on a precise control of the optical-Axis profile of the antennas on a subwavelength scale, in which the rotation angle of the optical axis has a simple linear relationship to the phase discontinuity. Such an approach enables effective wave front engineering within a subwavelength scale. © 2012 Optical Society of America.

Qiao Q.Q.,Nankai University | Zhang H.Z.,Nankai University | Li G.R.,Nankai University | Ye S.H.,Nankai University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Enhancement of the discharge capacity, high-rate capability, and cycle stability of the Li-rich layered Li(Li0.17Ni0.25Mn 0.58)O2 oxide with a large specific capacity is highly significant for high energy lithium-ion batteries. In this work, the Li-rich layered Li(Li0.17Ni0.25Mn0.58)O2 oxide is prepared by a spray-drying method. The surface modification with the Li-Mn-PO4 is introduced onto Li-rich layered Li(Li 0.17Ni0.25Mn0.58)O2 oxide for the first time. It is demonstrated that the surface of Li(Li0.17Ni 0.25Mn0.58)O2 grains is coated with the thin amorphous Li-Mn-PO4 layer (5 wt%). With increasing calcination temperature after the surface coating, a strong interaction can be induced on the interface between the amorphous Li-Mn-PO4 layer and the top surface of Li(Li0.17Ni0.25Mn0.58)O2 grains. As anticipated, the discharge capacity and high-rate capability are obviously improved for the Li-Mn-PO4-coated sample after calcination at 400 °C, while excellent cycle stability is obtained for the Li-Mn-PO 4-coated sample after calcination at 500 °C as compared with the as-prepared Li(Li0.17Ni0.25Mn0.58)O2 oxide during cycling. Apparently, the interface interaction between the amorphous Li-Mn-PO4 layer and the top surface of Li(Li 0.17Ni0.25Mn0.58)O2 grains is responsible for the improvement of the reaction kinetics and the electrochemical cycle stability of Li-Mn-PO4-coated samples. © 2013 The Royal Society of Chemistry.

Zhang J.,Southern Medical University | Gao J.,Nankai University | Chen M.,Southern Medical University | Yang Z.,Nankai University
Antioxidants and Redox Signaling | Year: 2014

Significance: Self-assembled nanostructures have received significant research interest in the last decade, because they show great promise for drug delivery, diagnostics, tissue engineering, and regenerative medicine. Recently, the development of enzyme-assisted self-assembled nanostructures has become an active area of research because of the attractive characteristics of enzymes, such as ready availability, good biocompatibility, and high selectivity and specificity. Phosphatases, taking part in approximately 30% of intra-and extracellular activities, have been widely employed as triggers for the generation of self-assembled biomaterials, including static, reversible, and dynamic systems. Recent Advances: In this review, we highlight the generation of self-assembled systems of synthetic molecules using phosphatases and their potential applications. We first summarize the generation of different kinds of static and dynamic self-assembled structures, including nanofibers and nanoparticles, by the dephosphorylation reaction catalyzed by phosphatases. The antagonistic interactions of phosphatases and kinases make this system one of the most attractive candidates for biotransformation. Diverse biomedical applications of phosphatases/kinases-involved self-assembled systems have been extensively explored in fields such as bacterial growth inhibition, drug delivery, imaging of self-assembly inside live cells, and biomineralization. We then summarize the reversible self-assembled systems controlled by the pair enzymes of phosphatases/kinases, in which different morphologies of self-assembled nanostructures can be achieved and switched by the pair enzymes. These phosphatase-involved self-assembled systems can be used for many applications such as controlled drug delivery, enzyme activity imaging, and cancer cell inhibition. Critical Issues: Phosphatases are over-expressed in several cancer cell lines. Their detection is, therefore, important for cancer diagnostics. Nanomaterials that can respond to abnormal phosphatase activities also have big potential for the delivery of therapeutic agents on demand. The study of reversible self-assembling systems control by the phosphatase/kinase switch may provide useful insights to understand the working principle of this important biological switch. Future Directions: The design principle mentioned in this review may stimulate the generation of smart self-assembled systems by other enzymes or other pairs of enzymes. The combination of environment- sensitive fluorescence property of fluorescent dyes and self-assembling molecules that can respond to enzymes may lead to the development of smart probes to monitor important biological processes. Antioxid. Redox Signal. 20, 2179-2190. © 2014 Mary Ann Liebert, Inc.

Zhang Z.,CNRS Paul Pascal Research Center | Zhang Z.,Nankai University | Grelet E.,CNRS Paul Pascal Research Center
Soft Matter | Year: 2013

Filamentous viruses of similar molecular and subunitary structure can form either a liquid crystalline nematic phase or a chiral nematic-also called cholesteric-phase, which is an elegant example of how self-organization of nanorods, with otherwise similar properties, can be affected by only subtle differences of surface properties and of the arrangement of the constituent subunits. In this work, we studied the influence of viral surface properties on the self-assembly of rod-like fd virus suspensions into the chiral nematic phase. For this purpose, the filamentous fd virus has been subjected to various chemical modifications on its capsid proteins: several organic molecules of different sizes and structures, including two popular fluorescent dyes (fluorescein and rhodamine), were coupled to the surface amino groups of the virus. The resulting chemically modified viruses still form a cholesteric phase in an aqueous suspension, but with a lower helicity compared to suspensions made of wild-type fd viruses. The degree of unwinding of the helical periodicity (or cholesteric pitch) depends on the structure of the labeled molecules. In addition, the chemically modified viruses exhibit a well-defined first order phase transition between the isotropic liquid and the liquid-crystalline state. Besides these modifications targeting the amino groups, the surface carboxyl groups were coupled with amino compounds so that the surface charge of fd viruses was reversed from negative to positive. The resulting particles can only form a nematic phase without any macroscopic helicity. These results suggest that inter-particle interactions, together with the intrinsic chirality of the virus, play an important role in the origin of the helical twist in the cholesteric phase. This journal is © 2013 The Royal Society of Chemistry.

Xin W.,Chinese PLA General Hospital | Wei W.,Nankai University | Li X.,Chinese PLA General Hospital
PLoS ONE | Year: 2012

Background: Effect of fish oil supplementation on flow-mediated dilation, an index of endothelial function in humans, remains controversial. We performed a meta-analysis to determine whether fish oil supplementation could improve endothelial function. Methods: Human intervention studies were identified by systematic searches of Medline, Embase, Cochrane's library and references of related reviews and studies. A random-effect model was applied to estimate the pooled results. Meta-regression and subgroup analyses were performed to evaluate the impact of study characteristics on the effect of fish oil supplementation on flow-mediated dilation. Results: A total of sixteen records with 1,385 subjects were reviewed. The results of the pooled analysis showed that fish oil supplementation significantly improved flow-mediated dilation (weighed mean difference: 1.49%, 95% confidence interval 0.48% to 2.50%, p = 0.004). Meta-regression and subgroup analysis suggested that the quality of included studies were inversely related to the overall effect (regression coefficient = -1.60, p = 0.04), and the significance of the effect was mainly driven by the studies with relatively poor quality. Sensitivity analysis including only double-blind, placebo-controlled studies indicated fish oil supplementation has no significant effect on endothelial function (weighed mean difference: 0.54%, 95% confidence interval -0.25% to 1.33%, p = 0.18). Besides, normoglycemic subjects or participants with lower diastolic blood pressure seemed to be associated with remarkable improvement of endothelial function after fish oil supplementation. Conclusions: Although current evidence suggested a possible role of fish oil in improving endothelial function, large-scale and high-quality clinical trials are needed to evaluate these effects before we can come to a definite conclusion. © 2012 Xin et al.

Xin W.,Chinese PLA General Hospital | Wei W.,Nankai University | Li X.,Chinese PLA General Hospital
Heart | Year: 2012

Context The effects of fish oil on cardiac function, ventricular remodelling and functional capacity in patients with chronic heart failure (CHF) remain controversial. Objective The aim of this meta-analysis was to evaluate effects of fish oil on cardiac function and related parameters in CHF patients. Data Sources Medline, Embase, the Cochrane Library and references cited in related reviews and studies. Study Selection Randomised controlled trials of fish oil supplementation on cardiac function in patients with CHF were identified. Data Extraction Two investigators read all papers and extracted all relevant information. A fixed effect or, in the presence of heterogeneity, a random effect model, was used to estimate the combined effects. Results 7 trials with 825 participants were included. Meta-analysis results showed that left ventricular ejection fraction was significantly increased (weighted mean difference (WMD) = 2.25%, 95% CI 0.66 to 3.83, p = 0.005) and left ventricular end-systolic volume was significantly decreased (WMD = 7.85 ml, 95% CI -15.57 to -0.12, p = 0.05) in the fish oil group compared with the placebo group, although left ventricular end-diastolic volume was not significantly affected. Meta-regression and subgroup analysis indicated that the improvement in left ventricular systolic function was more remarkable in patients with nonischaemic heart failure. Fish oil supplementation also improved the New York Heart Association functional classification and peak oxygen consumption in patients with non-ischaemic heart failure. Conclusions Improvement in cardiac function, remodelling and functional capacity may be important mechanisms underlying the potential therapeutic role of fish oil for patients with CHF. These effects might be more remarkable in patients with non-ischaemic heart failure. INTRODUCTION Chronic heart failure (CHF) is a complex clinical syndrome characterised by insufficient status of cardiac function, which can be caused by various structural or functional cardiovascular disorders.1 Despite impressive advances in medical management and device therapy in recent decades, CHF remains one of the leading causes of cardiovascular morbidity and mortality worldwide.2 3 Thus there is an urgent need for the development of novel treatment strategies for CHF despite the standard pharmacological therapies that have been recommended by current medical guidelines.4 5 Numerous clinical trials have shown supplementation with fish oil, which mainly consists of two categories of marine omega 3 polyunsaturated fatty acidsdeicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)dmay lower the risk of major cardiovascular events, such as myocardial infarction, sudden cardiac death (SCD), coronary artery disease and perhaps atrial fibrillation.6 7 Growing evidence from experimental and epidemiological studies suggested that fish oil intake could be beneficial for patients with CHF.8 9 Previous studies also indicated that fish oil could improve cardiac function and functional capacity in CHF patients; however, clinical trials have shown inconsistent results.10-16 Therefore, we performed a metaanalysis to systematically evaluate the effects of fish oil on cardiac function, remodelling and functional capacity in CHF. METHODS The study complied with the recently reported Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

Ren C.,Nankai University | Zhang J.,Southern Medical University | Chen M.,Southern Medical University | Yang Z.,Nankai University
Chemical Society Reviews | Year: 2014

Nano-materials formed by the self-assembly of small molecules are very promising for drug delivery, regenerative medicine, and detection of important analytes due to their unique properties, such as self-assembled multivalency, biocompatibility, and fast response to external stimuli. This tutorial review focuses on their applications in detection of important analytes. Self-assembling small molecules can show fast response to external stimuli. Therefore, the gel-sol/sol-gel phase transitions of supramolecular hydrogels that can be easily identified by naked eyes have been applied for the detection of enzymes and enzyme-involving analytes. The supramolecular hydrogels can also provide semi-wet environments that can retain the activity of enzymes and recognition properties of molecular probes. Thus, they provide good platforms for the detection of many biologically and environmentally important analytes. Besides, self-assembling small molecules show big differences in fluorescence or the F-NMR signal between their self-assembled and un-assembled stages. Such small molecules can be rationally designed through the integration of fluorescent dyes or fluorine containing molecules in the self-assembling small molecules. Therefore, extensive recent research efforts have been made to explore their detection applications based on the dis-assembly triggered fluorescence/F-NMR signal turn on or the self-assembly/aggregation induced fluorescence turn on. We believe that the research efforts made to this field will ultimately lead to the development of useful nano-materials for detection applications. © 2014 the Partner Organisations.

Cao S.,Nankai University | Dehmer M.,Institute for Bioinformatics and Translational Research | Shi Y.,Nankai University
Information Sciences | Year: 2014

Many graph invariants have been used for the construction of entropy-based measures to characterize the structure of complex networks. Based on Shannon's entropy, we study graph entropies which are based on vertex degrees by using so-called information functionals. When considering Shannon entropy-based graph measures, there has been very little work to find their extremal values. The main contribution of this paper is to prove some extremal values for the underlying graph entropy of certain families of graphs and to find the connection between the graph entropy and the sum of degree powers. Further, conjectures to determine extremal values of graph entropies are given. © 2014 Elsevier Inc. All rights reserved.

Chen X.,Nankai University | Gao J.,Renmin University of China
Soft Computing | Year: 2013

Term structure models describe the evolution of the yield curve through time, without considering the influence of risk, tax, etc. Recently, uncertain processes were initialized and applied to option pricing and currency model. Under the assumption of short interest rate following uncertain processes, this study investigates the term-structure equation. This equation is first derived for valuing zero-coupon bond. Finally, analytic solutions of the uncertain interest rate equation are given when the process of interest rate is assumed to be the uncertain counterparts of the Ho-Lee model and Vasicek model, respectively. © 2012 Springer-Verlag.

Dehmer M.,Institute for Bioinformatics and Translational Research | Shi Y.,Nankai University
PLoS ONE | Year: 2014

In this paper, we examine the uniqueness (discrimination power) of a newly proposed graph invariant based on the matrix DMAX defined by Randić et al. In order to do so, we use exhaustively generated graphs instead of special graph classes such as trees only. Using these graph classes allow us to generalize the findings towards complex networks as they usually do not possess any structural constraints. We obtain that the uniqueness of this newly proposed graph invariant is approximately as low as the uniqueness of the Balaban J index on exhaustively generated (general) graphs. Copyright: © 2014 Dehmer, Shi.

Chen R.,Fuzhou University | Xiang K.-N.,Nankai University
Journal of Combinatorial Theory. Series B | Year: 2012

In this paper, we prove that via an operation "reducing", every 3-connected representable matroid M with at least nine elements can be decomposed into a set of sequentially 4-connected matroids and three special matroids which we call freely-placed-line matroids, spike-like matroids and swirl-like matroids; more concretely, there is a labeled tree that gives a precise description of the way that M built from its pieces. © 2011.

Zheng C.,Nankai University | Zheng C.,University of Texas at Austin | Zhang T.,Nankai University
Neuroscience | Year: 2015

It is believed that phase synchronization facilitates neural communication and neural plasticity throughout the hippocampal-cortical network, and further supports cognition and memory. The pathway from the ventral hippocampus to the medial prefrontal cortex (mPFC) is thought to play a significant role in emotional memory processing. Therefore, the information transmission on the pathway was hypothesized to be disrupted in the depressive state, which could be related to its impaired synaptic plasticity. In this study, local field potentials (LFPs) from both ventral CA1 (vCA1) and mPFC were recorded in both normal and chronic unpredictable stress (CUS) model rats under urethane anesthesia. LFPs of all rats were recorded before and after the long-term potentiation (LTP) induced on the vCA1-mPFC pathway in order to figure out the correlation of oscillatory synchronization of LFPs and synaptic plasticity. Our results showed the vCA1-to-mPFC unidirectional phase coupling of the theta rhythm, rather than the power of either region, was significantly enhanced by LTP induction, with less enhancement in the CUS model rats compared to that in the normal rats. In addition, theta phase coupling was positively correlated with synaptic plasticity on vCA1-mPFC pathway. Moreover, the theta-slow gamma phase-amplitude coupling in vCA1 was long-term enhanced after high frequency stimulation. These results suggest that the impaired synaptic plasticity in vCA1-mPFC pathway could be reflected by the attenuated theta phase coupling and theta-gamma cross frequency coupling of LFPs in the depression state. © 2015 IBRO.

Gu Q.,Tianjin University of Technology and Education | Gao T.,Nankai University
Digital Signal Processing: A Review Journal | Year: 2013

Reversible watermarking can be applied to the protection for important digital media, such as medical and military image, it allows the watermark to be extracted and the original image to be restored completely, but reversible watermarking with stronger robustness is seldom discussed in existing literature. In this paper, a novel reversible watermarking algorithm based on chaotic system is proposed; chaotic system is not only used to search space of reversibility of the scheme, but also used to randomly select the position of watermarking embedding. Consequently, the proposed scheme achieves larger threshold space of reversibility and better performance of security. For some specific thresholds, the proposed algorithm is not only reversible, but also has stronger robustness against image compression. The experimental results show that the ergodicity and sensitivity to initial values of chaotic system play an important role in reversible watermarking algorithm, and the proposed scheme can achieve balance between reversibility and robustness with the help of chaotic system. © 2012 Elsevier Inc. All rights reserved.

Han D.,University of Central Florida | Sun W.,Nankai University
IEEE Transactions on Information Theory | Year: 2014

We propose new approaches to the problems of recovering signals from the rearranged frame coefficients or frame coefficients with erasures at either known or unknown locations. These problems naturally arise from applications, where the encoded information needs to be transmitted, for example, in signal/image processing, information and coding theory, and communications. We show that with the appropriate choices of the frames that are used for encoding, the signal with erasures occurring at known locations can be easily recovered without inverting the (sub)frame operators each time. Our new easy to implement and cost-efficient algorithm provides perfect reconstruction of the original signal. To address the problem of recovering erased coefficients from unknown locations, we propose to use a class of frames that are almost robust with respect to \(m\) -erasures. We prove that every frame with uniform excess can be rescaled to an almost robust frame and the locations of erased data can be perfectly recovered for almost all the signals. Similar results are obtained for recovering the original order of a disordered (rearranged) set of frame coefficients. Numerical examples are presented to test the main results. Whenever the received data are noise free, we can recover the original signal exactly from frame coefficients with erasures at unknown locations or from a disordered set of frame coefficients. © 2014 IEEE.

Chen P.,Tianjin University | Zhong Y.,Tianjin University | Liu H.,Nankai University
Optics Letters | Year: 2013

Light absorption by thin-film amorphous Si solar cells patterned with metallic nanogratings is investigated theoretically. Propagative bounded modes that include the surface plasmon polariton (SPP) and the photonic mode (PM) are extracted from the total field to quantitatively evaluate their contribution to the light absorption. Our results show that after removing the propagative bounded modes from the total field, the residual field still contributes to a major part of the total light absorption. This proves, at a quantitative level, that the light absorption of the structure is largely attributed to the residual field that is composed of unbounded or evanescent modes arising from the grating scattering, and the SPP and the PM do not play a dominant role, which is out of the previous intuitive expectations. © 2013 Optical Society of America.

Ke H.-W.,Tianjin University | Wei Z.-T.,Nankai University | Li X.-Q.,Nankai University
European Physical Journal C | Year: 2013

Assuming the newly observed Z c(3900) to be a molecular state of DD̄*(D*D̄), we calculate the partial widths of Zc(3900)→J/ψ+π; ψ′+π; η c+ρ and DD̄* within the light-front model (LFM). Z c(3900)→J/ψ+π is the channel by which Zc(3900) was observed, our calculation indicates that it is indeed one of the dominant modes whose width can be in the range of a few MeV depending on the model parameters. Similar to Zb and Zb′, Voloshin suggested that there should be a resonance Zc′ at 4030 MeV, which can be a molecular state of D*D̄*. Then we go on calculating its decay rates to all the aforementioned final states and the D*D̄* as well. It is found that if Zc(3900) is a molecular state of (Formula presented.), the partial width of Zc(3900) ̄ DD̄* is rather small, but the rate of Zc(3900)→ψ(2s)π is even larger than Zc(3900)→J/ψπ. The implications are discussed and it is indicated that with the luminosity of BES and BELLE, the experiments may finally determine if Zc(3900) is a molecular state or a tetraquark. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

Chen Z.,San Francisco State University | Chen Z.,Nankai University | Segev M.,Technion - Israel Institute of Technology | Christodoulides D.N.,University of Central Florida
Reports on Progress in Physics | Year: 2012

Solitons, nonlinear self-trapped wavepackets, have been extensively studied in many and diverse branches of physics such as optics, plasmas, condensed matter physics, fluid mechanics, particle physics and even astrophysics. Interestingly, over the past two decades, the field of solitons and related nonlinear phenomena has been substantially advanced and enriched by research and discoveries in nonlinear optics. While optical solitons have been vigorously investigated in both spatial and temporal domains, it is now fair to say that much soliton research has been mainly driven by the work on optical spatial solitons. This is partly due to the fact that although temporal solitons as realized in fiber optic systems are fundamentally one-dimensional entities, the high dimensionality associated with their spatial counterparts has opened up altogether new scientific possibilities in soliton research. Another reason is related to the response time of the nonlinearity. Unlike temporal optical solitons, spatial solitons have been realized by employing a variety of noninstantaneous nonlinearities, ranging from the nonlinearities in photorefractive materials and liquid crystals to the nonlinearities mediated by the thermal effect, thermophoresis and the gradient force in colloidal suspensions. Such a diversity of nonlinear effects has given rise to numerous soliton phenomena that could otherwise not be envisioned, because for decades scientists were of the mindset that solitons must strictly be the exact solutions of the cubic nonlinear Schrödinger equation as established for ideal Kerr nonlinear media. As such, the discoveries of optical spatial solitons in different systems and associated new phenomena have stimulated broad interest in soliton research. In particular, the study of incoherent solitons and discrete spatial solitons in optical periodic media not only led to advances in our understanding of fundamental processes in nonlinear optics and photonics, but also had a very important impact on a variety of other disciplines in nonlinear science. In this paper, we provide a brief overview of optical spatial solitons. This review will cover a variety of issues pertaining to self-trapped waves supported by different types of nonlinearities, as well as various families of spatial solitons such as optical lattice solitons and surface solitons. Recent developments in the area of optical spatial solitons, such as 3D light bullets, subwavelength solitons, self-trapping in soft condensed matter and spatial solitons in systems with parity-time symmetry will also be discussed briefly. © 2012 IOP Publishing Ltd.

Wu Z.,Nankai University | Ge S.,Petrochina
Catalysis Communications | Year: 2011

A Co-B nanoparticle catalyst was prepared by a modified polyol method. Borohydride served both as a reducing agent for Co2+ and as a boron source, and the solvent, ethylene glycol, served as the surfactant and stabilizer to assemble Co-B clusters into small and uniform particles. The as-prepared Co-B possessed high surface active metal area and highly unsaturated coordinated Co metal, resulting in lower activation energy and higher hydrogen generation rate for hydrolysis of alkaline NaBH4 solution than the conventional Co-B catalyst synthesized from chemical reduction in water bath. © 2011 Elsevier B.V. All rights reserved.

He H.,Tianjin University | Li S.,Nankai University | Wang S.,Tianjin University | Hu M.,Tianjin University | And 2 more authors.
Nature Photonics | Year: 2012

Green fluorescent protein (GFP) is one of the most widely studied and exploited proteins in biochemistry and cell biology. It emits fluorescence following optical excitation, which is usually provided by a laser. Here, we report that fluorescence from enhanced GFP can be 'turned off' by exposing cells to laser light. A short flash of femtosecond laser light is shown to deplete calcium in the endoplasmic reticulum of cells. Calcium-release-activated calcium channels are then activated by stromal interaction molecule 1 (STIM1). The rise in intracellular Ca 2+ depolarizes mitochondria and increases the leakage of reactive oxygen species, which then permanently bleach the GFP. This controllable optical scheme for reactive oxygen species generation can also be used to modulate the photoconversion of GFP fluorescence from green to red emission and provide a mechanism for influencing cellular molecular dynamics. © 2012 Macmillan Publishers Limited. All rights reserved.

Zhang B.,Nankai University | Qin X.,Tianjin University | Li G.R.,Nankai University | Gao X.P.,Nankai University
Energy and Environmental Science | Year: 2010

To enhance the long stability of sulfur cathode for a high energy lithium-sulfur battery system, a sulfur-carbon sphere composite was prepared by encapsulating sulfur into micropores of carbon spheres by thermal treatment of a mixture of sublimed sulfur and carbon spheres. The elemental sulfur exists as a highly dispersed state inside the micropores of carbon spheres with a large surface area and a narrow pore distribution, based on the analyses of the X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), thermogravimetry (TG) and local element line-scanning. It is demonstrated from galvanostatic discharge-charge process, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) that the sulfur-carbon sphere composite has a large reversible capacity and an excellent high rate discharge capability as cathode materials. In particular, the sulfur-carbon sphere composite with 42 wt% sulfur presents a long electrochemical stability up to 500 cycles, based on the constrained electrochemical reaction inside the narrow micropores of carbon spheres due to strong adsorption. Therefore, the electrochemical reaction constrained inside the micropores proposed here would be the dominant factor for the enhanced long stability of the sulfur cathode. The knowledge acquired in this study is important not only for the design of efficient new electrode materials, but also for understanding the effect of the micropores on the electrochemical cycle stability. © 2010 The Royal Society of Chemistry.

Xing B.,Taiyuan University of Technology | Wang G.-C.,Nankai University | Wang G.-C.,Shanxi Institute of Coal CAS Chemistry
Physical Chemistry Chemical Physics | Year: 2014

Density functional theory calculations are presented for adsorption and dissociation of NH3, H2O, CH3OH, H2S and C2H4 on clean and oxygen atom pre-adsorbed metal surfaces (Cu, Ag, Au, Ni, Pd, Pt, Rh, Ru, Os and Ir). The calculation results indicated that the oxygen-promotion effect depends both on the metallic activity and the character of the X-H bond. On the one hand, for a given reaction on a series metals, a good linear correlation was found between the energy barrier difference of X-H bond breaking on clean and oxygen-covered metals and the binding strength of oxygen on metals, namely an oxygen-promotion effect was favorable to the less active metals but unfavorable to the more active metals. On the other hand, for a series of X-H bond breaking reactions on a given metal, it was found that the promotion effect follows the trend of O-H > N-H > C-H, that is, the O-H bond is most promoted by the oxygen atom. The possible reason is the O-H bond forms the strongest hydrogen bond in the transition state among the X-H bonds investigated in this work. Additionally, it was found that the oxygen coverage has little effect on the X-H bond scission. © 2014 the Owner Societies.

Hu Z.,Ningbo University | Hu Z.,Nankai University | Zhang J.,Nankai University | Zhu Y.,Ningbo University
Renewable Energy | Year: 2014

We investigated the effects of poly(3, 4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films treated with methoxyethanol (ME) on the performance of polymer solar cells, and the effects were compared with the PEDOT:PSS films treated with dimethyl sulfoxide (DMSO). In particular, a correlation between the performance parameters of polymer solar cells and changes in the conductivity, surface morphology, and work function of treated PEDOT:PSS was investigated as a function of an added ME and DMSO ratio. The enhanced conductivity of the treated PEDOT:PSS improved the short circuit current and reduced the series resistance of solar cells. While the enhanced conductivity and surface roughness of the treated PEDOT:PSS also induced the large leakage current and sacrificed the device FF. The open circuit voltage was almost constant, although the slightly reduced voltage was observed. © 2013 .

Li K.,Nankai University | Liu S.,Nankai University | Liu X.,Tianjin University
International Journal of Energy Research | Year: 2014

SUMMARY: Because of rapid growth in population and industrialization, worldwide ethanol demand is increasing continuously. The first-generation and second-generation biofuels are unable to meet the global demand of bioethanol production because of their primary value of food and feed. Therefore, algae are among the most potentially significant sources of sustainable biofuels in the future of renewable energy because of the accumulating high starch/cellulose and because they are widely distributed in nature. The focus of this paper is to review the production and recent advances in research and development in the algae bioethanol, including pretreatment, hydrolysis, and fermentation of algae biomass. Despite the many developments made in the recent years, commercialization of algal bioethanol remains challenging chiefly because of the techno-economic constraints. Technological breakthroughs in all major aspects must be overcome before it can be a successfully large-scale and commercialized product. © 2014 John Wiley & Sons, Ltd.

Cui H.,Nanjing Agricultural University | Cui C.,Nankai University
Dalton Transactions | Year: 2015

Reaction of the N-heterocyclic carbene (NHC)-stabilized silylene ArN(SiMe3)Si(IiPr)Cl (1, Ar = 2,6-iPr2C6H3, IiPr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) with SiCl4 resulted in the formation of three different products NHC-stabilized dichlorosilaimine ArNSi(IiPr)Cl2 (2), aminotrichlorosilane ArN(SiMe3)SiCl3 (3) and a silaimine dimer (ArNSiCl2)2 (4) under different conditions. The products can be controlled by reaction conditions. Compound 2 is the first example of a less bulky NHC-supported silaimine via the reaction of a silylene with SiCl4. © 2015 The Royal Society of Chemistry.

Su L.,Nankai University | Zhou Z.,Nankai University | Qin X.,Tianjin University | Tang Q.,Tianjin University | And 2 more authors.
Nano Energy | Year: 2013

The composites of CoCO3 submicrocubes and graphene nanosheets (GNSs) were prepared through a solvothermal route and were tested as anode materials for lithium ion batteries. Profiting from the advantages of GNSs, CoCO3/GNS composites delivered high capacities of over 1000mAhg-1, much higher than theoretical values based on available lithium storage mechanisms. Instead, we propose an electrochemical catalytic conversion mechanism for lithium storage, in which not only cations (Co2+) but also anions (CO3 2-) are involved in the electron transfer. C4+ in CO3 2- is reduced to C0 or other low-valence C under the electrochemical catalysis of newly-generated Co nanoparticles. This new mechanism may provide more clues for exploiting advanced materials for Li ion batteries and other energy storage devices. © 2012 Elsevier Ltd.

A kind of novel diamino moiety functionalized silica nanoparticles with the diameter of ∼110 nm was successfully prepared and characterised by transmission electron microscope (TEM) and elemental analysis. Capillary electrophoresis (CE) with this kind of nanoparticles as pseudostationary phase was developed for the simultaneous analysis of five organic acids in beverage and fruit samples. The effects of pH, buffer concentration, and nanoparticles concentration on separation were carefully investigated. Five organic acids were baseline separated in 5 min under optimum experimental conditions. The precisions for five replicate separations of a standard mixture solution were 2.71-6.13% for peak area and 1.22-1.93% for migration time respectively. The detection limits were 7.5, 0.15, 0.23, 0.33 and 10.0 mg/L for citric acid, salicylic acid, benzoic acid, sorbic acid and ascorbic acid, respectively. The developed method was applied to the simultaneous analysis of five analytes in beverage and fruit samples and certified reference materials with satisfactory results. © 2013 Published by Elsevier Ltd.

Du P.,Tianjin University | Wang X.,Tianjin University | Xu C.,Tianjin University | Gao Y.,Nankai University
Analytical Biochemistry | Year: 2012

The pseudo-amino acid composition has been widely used to convert complicated protein sequences with various lengths to fixed length digital feature vectors while keeping considerable sequence order information. However, so far the only software available to the public is the web server PseAAC (http://www.csbio.sjtu.edu.cn/bioinf/PseAAC), which has some limitations in dealing with large-scale datasets. Here, we propose a new cross-platform stand-alone software program, called PseAAC-Builder (http://www.pseb.sf.net), which can be used to generate various modes of Chou's pseudo-amino acid composition in a much more efficient and flexible way. It is anticipated that PseAAC-Builder may become a useful tool for studying various protein attributes. © 2012 Elsevier Inc. All rights reserved.

Cao Y.,Nankai University | He T.,CAS National Center for Nanoscience and Technology | Chen Y.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2010

A new type of composite film (heterostructure) with optoelectronic properties have been prepared by coupling Sn-doped rutile TiO2 (R-TiO2-Sn) and N-doped anatase TiO2 (A-TiO2-N) with use of a sol-gel method. Under visible and UV light irradiation, it exhibits a higher photocatalytic activity than both R-TiO2-Sn and A-TiO2-N films due to the formation of a heterojunction at the interface, as well as the increase of total amount of photogenerated charge carriers and introduction of doping states. If R-TiO2-Sn is the outmost layer, moreover, the composite film shows a much higher photodegradation capability of HCHO than that when A-TiO2-N is the outmost layer. Our results offer a paradigm for developing optoelectronic functional materials that can be used in many fields, such as solar cells, photocatalysis, and photosynthesis. © 2010 American Chemical Society.

Ke H.-W.,Tianjin University | Li X.-Q.,Nankai University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Since the discovery of X(3872), its structure has been in ceaseless dispute. The data of X(3872)→π +π -π0J/ψ suggest that X(3872) may be a high-spin charmoniumlike particle of 2 -+. In terms of the light-front quark model we calculate the rates of the radiative decays X(3872)→J/ψ(ψ ′) γ supposing X(3872) to be a 2 -+ charmonium. Within this framework, our theoretical prediction on BR(X(3872)→ψ(1S)γ) is at order of 10 -3 which is slightly lower than the BABAR Collaboration's data but close to the Belle Collaboration's. Our prediction on BR(X(3872)→ψ ′γ) is at order of 10 -5 if ψ ′ is a pure 2S state or 10 -4 if ψ ′ is a 2S-1D mixture, which does not conflict with the upper bound set by Belle, but is much lower than BABAR's data. Thus if the future measurement decides the branching ratio of BR(X(3872) →ψ ′γ) to be much larger than 10 -4, the 2 -+ assignment for X(3872) should be ruled out. © 2011 American Physical Society.

Li G.,Anhui University | Chen X.,CAS Shanghai Institute of Technical Physics | Gao G.,Nankai University
Nanoscale | Year: 2014

In this work, we synthesized 3D Bi2S3 microspheres comprised of nanorods grown along the (211) facet on graphene sheets by a solvothermal route, and investigated its catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs. Although the (211) facet has a large band gap for a Bi2S3 semiconductor, owing to the introduction of graphene into the system, its short-circuit current density, open-circuit voltage, fill factor, and efficiency were Jsc = 12.2 mA cm-2, Voc = 0.75 V, FF = 0.60, and η = 5.5%, respectively. By integrating it with graphene sheets, our material achieved the conversion efficiency of 5.5%, which is almost triple the best conversion efficiency value of the DSSCs with (211)-faceted 3D Bi2S3 without graphene (1.9%) reported in the latest literature. Since this conversion-efficient 3D material grown on the graphene sheets significantly improves its catalytic properties, it paves the way for designing and applying low-cost Pt-free CE materials in DSSC from inorganic nanostructures. This journal is © The Royal Society of Chemistry.

Hu X.,Nankai University | Mu L.,Tianjin University | Wen J.,Tianjin University | Zhou Q.,Nankai University
Journal of Hazardous Materials | Year: 2012

The contaminations of peptide toxins in drinking water lead directly to sickness and even death in both humans and animals. A smart RNA as aptamer is covalently immobilized on graphene oxide to form a polydispersed and stable RNA-graphene oxide nanosheet. RNA-graphene oxide nanosheets can resist nuclease and natural organic matter, and specifically adsorb trace peptide toxin (microcystin-LR) in drinking water. The adsorption data fit the pseudo-second-order kinetics and the Langmuir isotherm model. The adsorption capacity of RNA-graphene oxide nanosheets decreases at extreme pH, temperature, ionic strength and natural organic matter, but it is suitable to adsorb trance pollutants in contaminated drinking water. Compared with other chemical and biological sorbents, RNA-graphene oxide nanosheets present specific and competitive adsorption, and are easily synthesized and regenerated. Aptamer (RNA) covalently immobilized on graphene oxide nanosheets is a potentially useful tool in recognizing, enriching and separating small molecules and biomacromolecules in the purification of contaminated water and the preparation of samples. © 2012 Elsevier B.V.

Yue C.-Y.,Nankai University | Ding G.-S.,Tianjin University | Liu F.-J.,Nankai University | Tang A.-N.,Nankai University
Journal of Chromatography A | Year: 2013

A novel approach based on surface molecularly imprinted technique is demonstrated for the synthesis of surface molecularly imprinted silica nanoparticles (MI-SiNPs) in aqueous media, using l-tryptophan (l-Trp) as template molecule. The MI-SiNPs were fully characterized by transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and atomic force microscopy (AFM), and the results showed MI-SiNPs thus prepared were uniform in particle size (~87nm) with a distinct core-shell structure with shell thickness of ~7nm. The terminal carboxyl groups endowed the MI-SiNPs with good water-compatibility, and so good suspension stability for MI-SiNPs in water-rich buffer solutions can be easily achieved without the addition of any other reagents. When MI-SiNPs were used as pseudostationary phases (PSPs) in electrokinetic chromatography (EKC) for the enantioseparation of Trp, a resolution of 2.73 can be achieved in less than 10min with symmetric peaks. These excellent separation features are mainly attributed to the fast mass transfer and good accessibility of the interaction sites locating at the surface of the MI-SiNPs. The effects of some important separation factors, e.g., pH and concentration of buffer solution, content of MI-SiNPs added, content of organic modifier in buffer solution, on the enantioseparation of Trp were studied, and an optimum separation condition of 30% (v/v) acetonitrile in 20mmolL-1 phosphate buffer (pH 7.0), with 0.50mgmL-1 MI-SiNPs added was ultimately selected. © 2013 Elsevier B.V.

Xing B.,Nankai University | Pang X.-Y.,Taiyuan University of Technology | Wang G.-C.,Nankai University
Journal of Catalysis | Year: 2011

Density functional theory calculations are presented for adsorption and dissociation of CH4 on clean and oxygen atom pre-adsorbed metal surfaces (Cu, Ag, Au, Ni, Pd, Pt, Ru, Rh, Os, Ir, and Mo). The total energy change and the activation barrier have been calculated for the direct and the oxygen-assisted cleavage of the C-H bonds. Our results indicate that pre-adsorbed oxygen promotes the CH4 dissociation process on IB group metal surfaces, but inhibits the dissociation process on transition metal surfaces. A good Brønsted-Evans-Polanyi correlation for CH4 dissociation on clean and atomic oxygen pre-adsorbed metal surfaces is found, which is helpful to reveal the nature of CH4 dissociation. From the analysis of activation barrier, we expect our work can provide a clear understanding of the nature of CH4 dissociation. © 2011 Elsevier Inc. All rights reserved.

Zhu L.-N.,Tianjin University | Wu B.,Tianjin University | Kong D.-M.,Tianjin University | Kong D.-M.,Nankai University
Nucleic Acids Research | Year: 2013

Ligands targeting telomeric G-quadruplexs are considered good candidates for anticancer drugs. However, current studies on G-quadruplex ligands focus exclusively on the interactions of ligands and monomeric G-quadruplexes under dilute conditions. Living cells are crowded with biomacromolecules, and the ∼200-nucleotide G-rich single-stranded overhang of human telomeric DNA has the potential to fold into multimeric G-quadruplex structures containing several G-quadruplex units. Studies on interactions between ligands and multimeric G-quadruplexes under molecular crowding conditions could provide a new route for screening specific telomeric G-quadruplex-targeting ligands. Herein, TMPipEOPP, a cationic porphyrin derivative designed by us, was demonstrated as a promising multimeric telomeric G-quadruplex ligand under molecular crowding conditions. It could highly specifically recognize G-quadruplexes. It could also promote the formation of G-quadruplexes and stabilize them. Detailed studies showed that TMPipEOPP interacted with monomeric G-quadruplexes in sandwich-like end-stacking mode of quadruplex/TMPipEOPP/quadruplex and interacted with multimeric human telomeric G-quadruplexes by intercalating into the pocket between two adjacent G-quadruplex units. The pocket size greatly affected TMPipEOPP binding. A larger pocket was advantageous for the intercalation of TMPipEOPP. This work provides new insights into the ligand-binding properties of multimeric G-quadruplexes under molecular crowding conditions and introduces a new route for screening anticancer drugs targeting telomeric G-quadruplexes. © 2013 The Author(s).

Zhang P.,Nankai University | Li K.,Nankai University | Liu X.,Tianjin University
Journal of Power Sources | Year: 2014

Highly active and low-cost electrocatalysts are of great importance for large-scale commercial applications of microbial fuel cells (MFCs). In this work, we prepared an activated carbon (AC) air cathode containing electrodeposited γ-MnO2 using a potentiostatic method. The results indicated that carnation-like MnO2 crystals were bound to the surface of the AC air cathode after a deposition time of 10 min, which greatly improved the performance of the cathode. BET analysis results demonstrated that the electrodeposition of MnO2 decreased the micropore surface area of the cathode but increased the mesopore surface area. When compared with a bare AC air cathode, the electrodeposited MnO2 cathode exhibited higher catalytic activity for oxygen reduction reaction. The maximum power density of the MFC equipped with the electrodeposited MnO2 AC air cathode was 1554 mW m-2, which is 1.5 times higher than the control cathode. © 2014 Elsevier B.V. All rights reserved.

Wang E.,Nankai University | He T.,CAS National Center for Nanoscience and Technology | Zhao L.,Nankai University | Chen Y.,Beijing University of Chemical Technology | Cao Y.,Nankai University
Journal of Materials Chemistry | Year: 2011

Tin and nitrogen co-doped titania has been prepared by a hydrolysis precipitation method and studied by X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance UV-vis absorption spectra, and photoluminescence. The surface area has been determined by using the BET method. Tin is incorporated into the TiO2 crystal lattice in substitutional mode, while nitrogen is present as surface species. The resultant energy levels of tin doping and nitrogen surface states are located inside the bandgap, which are close to the conduction and valence bands, respectively. Hence, co-doping of tin and nitrogen can greatly enhance the absorption in the visible light region and inhibit the recombination of photogenerated charge carriers, leading to a higher photocatalytic activity for the co-doped catalyst than pure TiO 2 and solely doped TiO2 with nitrogen or tin for degradation of 4-chlorophenol under both visible and UV-light irradiation. This indicates that co-doping simultaneously with two foreign elements is a feasible way to improve the photocatalytic activity of TiO2. © The Royal Society of Chemistry.

Ke H.-W.,Tianjin University | Liu T.,Tianjin University | Li X.-Q.,Nankai University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The LHCb Collaboration has systematically measured the rates of Bc→J/ψK, Bc→J/ψDs, Bc→J/ψDs*, and Bc→ψ(2S)π. The new data enable us to study relevant theoretical models and further determine the model parameters. In this work, we calculate the form factors for the transitions Bc→J/ψ and Bc→ψ(2S) numerically and then determine the partial widths of the semileptonic and nonleptonic decays. The theoretical predictions on the ratios of Γ(Bc→J/ψK)/Γ(Bc→J/ψπ), Γ(Bc→J/ ψDs)/Γ(Bc→J/ψπ), and Γ(Bc→J/ψDs*)/ Γ(Bc→J/ψπ) are consistent with data within only 1σ. Especially, for calculating Γ(Bc→ψ(2S)X) the modified harmonic oscillator wave function which we developed in early works is employed, and the results indicate that the modified harmonic oscillator wave function works well. © 2014 American Physical Society.

Wang C.-C.,Tianjin University | Niu Z.-G.,Tianjin University | Zhang Y.,Nankai University
Journal of Hazardous Materials | Year: 2013

To estimate the concentration in air and the cancer risk of irrigation workers and the public exposed to the total trihalomethanes (TTHMs) in reclaimed water used for landscape irrigation, a probabilistic health risk assessment was conducted through the integrated use of one-dimensional (1-D) and two-dimensional (2-D) Monte Carlo simulations. Before the 2-D simulation, a sensitivity analysis corresponding to the 1-D simulation was carried out to identity the factors most affecting the outputs. The results reveal that the TTHM concentration level and cancer risk for workers' exposure is much higher than that for public exposure in landscape irrigation. Moreover, the most influential factors are quite different for workers' exposure and public exposure. The 2-D Monte Carlo risk analysis result for the workers indicated that the lowest-risk, highest-risk and two critical points for irrigation height are 0.7. m, 1.53. m, 1.4. m and 1.65. m when the mean value of the risk is selected as the reference statistic for risk management. Based on the risk assessment results, different measures can be suggested for the risk control of different populations. Furthermore, the influential variables should be better characterized to improve the accuracy of health risk assessment. © 2013 Elsevier B.V.

Ke H.-W.,Tianjin University | Li X.-Q.,Nankai University
European Physical Journal C | Year: 2011

While the light-front quark model (LFQM) is employed to calculate hadronic transition matrix elements, the vertex functions must be pre-determined. In this work we derive the vertex functions for all d-wave states in this model. Especially, since both 3D1 and 3S1 are 1-- mesons, the Lorentz structures of their vertex functions are the same. Thus when one needs to study the processes where 3D1 is involved, all the corresponding formulas for 3S1 states can be directly applied; only the coefficient of the vertex function should be replaced by that for 3D1. The results would be useful for studying the newly observed resonances, which are supposed to be d-wave mesons, and furthermore possible 2S-1D mixing in ψ′ with the LFQM. © 2011 Springer-Verlag / Società Italiana di Fisica.

Ke H.-W.,Tianjin University | Li X.-Q.,Nankai University | Wei Z.-T.,Nankai University
European Physical Journal C | Year: 2010

The mixing of η-η′ or η-η′-G is of a great theoretical interest, because it concerns many aspects of the underlying dynamics and hadronic structure of pseudoscalar mesons and glueball. Determining the mixing parameters by fitting data is by no means trivial. In order to extract the mixing parameters from the available processes where hadrons are involved, theoretical evaluation of hadronic matrix elements is necessary. Therefore model dependence is somehow unavoidable. In fact, it is impossible to extract the mixing angle from a unique experiment because the model parameters must be obtained by fitting other experiments. Recently BR(D→η+l̄+vl) and BR(Ds→η(η′)+l̄+vl) have been measured, thus we are able to determine the η-η′ mixing solely from the semileptonic decays of D-mesons where contamination from the final state interactions is absent. Thus we hope that the model dependence of the extraction can be somehow alleviated. Once BR(D→η′+l̄+vl) is measured, we can further determine all the mixing parameters for η-η′-G. As more data are accumulated, the determination will be more accurate. In this work, we obtain the transition matrix elements of D(s)→η(′) using the light-front quark model whose feasibility and reasonability for such processes have been tested. © 2010 Springer-Verlag / Società Italiana di Fisica.

Wu H.,Nankai University | Zhang L.-L.,Tianjin University | Tian Z.-Q.,Nankai University | Huang Y.-D.,Tianjin University | Wang Y.-M.,Nankai University
Chemistry - A European Journal | Year: 2013

Bispirooxindole derivatives containing three stereocenters, including two spiro quaternary centers, were synthesized in a high-yielding, atypically rapid, and stereocontrolled cascade Michael-cyclization reaction between methyleneindolinones and isothiocyanato oxindoles catalyzed by a bi- or multifunctional organocatalyst. Mild conditions were used to construct bispirooxindoles with excellent enantio- and diastereomeric purities within less than 1 min. Catalyst reconfiguration offered access to the opposite enantiomer. This exceptionally highly efficient procedure will allow diversity-oriented syntheses of this intriguing class of compounds with potential biological activities. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hu X.,Nankai University | Mu L.,Tianjin University | Wen J.,Tianjin University | Zhou Q.,Nankai University
Carbon | Year: 2012

A novel photocatalyst, graphene oxide (GO) functioned aptamer, was covalently synthesized and characterized as being composed of photosensitive GO and target recognition aptamer. Aptamer enhanced photocatalytic activities of GO were studied under broad visible-light spectrum. The complex photocatalyst effectively inactivated viruses, and damaged the proteins capsid and nucleic acids of viruses in irradiation. Subsequently, the proteins posed carbonylation and the nucleic acid bases (especially for guanosine) received oxidized modification. GO was reduced by loss of oxygen elements. GO-aptamer and viruses constituted a redox system under visible-light irradiation. The photocatalysis paths involved energy transfer (generation of singlet oxygen), electron transfer (generation of anion radicals) and water dissociation (generation of the precursor to the hydrated electron). GO-aptamer is a smart photocatalyst to selectively photocatalyze of nucleic acids and proteins, which is attractive in environment protection, biochemical engineering and phototherapy. © 2012 Elsevier Ltd. All rights reserved.

Duan X.,Nankai University | Ma J.,Hunan University | Lian J.,Chinese University of Hong Kong | Zheng W.,Nankai University
CrystEngComm | Year: 2014

Wet chemistry using ionic liquids as the medium has proven to be highly efficient for the preparation of several types of metallic, metal oxides, and other kinds of semiconductor nanostructures, and so on. This article reviews state-of-the-art research activities in the field, focusing on the use of ionic liquids as a versatile regent for the synthesis of various nanoparticle systems. We begin with a survey of choices to explore the ability of ionic liquids to act as a reactant, solvent, and surfactant, as a function of other synthesis parameters, also denoted as ionic liquid precursors (or task-special ionic liquids), which offer many advantages over traditional solution-phase methods. We then examine the design and fabrication of functional inorganic materials by means of optimizing the effect models of ionic liquids. Many of the most recent advances in ionothermal or ionic liquid-assisted synthesis have been realized by appropriate choice of cations or anions of ionic liquids according to the need. This review also highlights crucial issues that should be addressed in future research activities. This journal is © 2014 The Royal Society of Chemistry.

White J.F.,U.S. National Institutes of Health | Noinaj N.,U.S. National Institute of Diabetes and Digestive and Kidney Diseases | Shibata Y.,University of Cambridge | Love J.,New York Structural Biology Center | And 10 more authors.
Nature | Year: 2012

Neurotensin (NTS) is a 13-amino-acid peptide that functions as both a neurotransmitter and a hormone through the activation of the neurotensin receptor NTSR1, a G-protein-coupled receptor (GPCR). In the brain, NTS modulates the activity of dopaminergic systems, opioid-independent analgesia, and the inhibition of food intake; in the gut, NTS regulates a range of digestive processes. Here we present the structure at 2.8Å resolution of Rattus norvegicus NTSR1 in an active-like state, bound to NTS 8-13, the carboxy-terminal portion of NTS responsible for agonist-induced activation of the receptor. The peptide agonist binds to NTSR1 in an extended conformation nearly perpendicular to the membrane plane, with the C terminus oriented towards the receptor core. Our findings provide, to our knowledge, the first insight into the binding mode of a peptide agonist to a GPCR and may support the development of non-peptide ligands that could be useful in the treatment of neurological disorders, cancer and obesity. © 2012 Macmillan Publishers Limited. All rights reserved.

Ren S.,Chinese University of Hong Kong | Xie Z.,Nankai University
Organometallics | Year: 2011

Reactions ofCp2Zr(μ-Cl)(μ-C 2B 10H 10)Li(OEt 2)2 (1) with various N-heterocycles derived from pyridine were studied. Treatment of 1 with pyridine, 2-bromopyridine, 2, 4-lutidine, quinoline, and 2-(1-hexynyl)pyridine generated α-C-H activation (σ-bond metathesis) products Cp2Zr(η2-C, N-C5H4N)(σ-C2B10H11) (2), Cp2Zr[η2-C,N-(6-Br-C 5H 3NN)](σ- C2B10H11) (3), Cp2Zr[η2-C,N-(4,6-Me2-C5H2N)] (σ-C2B10H11) (4), Cp2Zr(η2-C,N-C9H6N)(σ-C2B10H11) (5), and Cp2Zr- {η2-C,N-[6-(nBuCtC)-C 5H 3NN]}(σ-C2B10H11) (7), respectively. On the other hand, reaction of 1 with acridine gave the addition product 1,2-[Cp2Zr(10,9-C13H9N)]-1,2-C 2B 10H 10 (6) in 85% isolated yield. Complex 1 reacted with 3-(1-hexynyl)pyridine to afford α-C-H activation species Cp2Zr{η2-C,N-[5-(nBuCtC)C 5H 3NN]}(σ-C2B10H11) (8a) andCp2Zr{η2-C,N-[3-(nBuCtC)C 5H 3NN]}-(σ- C2B10H11) (8b) in a molar ratio of 42:58, as determined by the 1H NMR spectrum. In the presence of CuI, however, the CtC insertion products zirconacyclopentenes 1,2-[Cp2ZrC(2-C5H4N)dCR]-1,2-C 2B 10H 10 [R = Bun (9), Ph (10)] were obtained in 74-77% yields. It is suggested that the coordination of pyridine to the Zr atom is crucial for α-C-H activation (σ-bond metathesis). The presence of CuI can alter the reaction path by preventing the coordination of pyridine to the Zr atom, which blocks the α-C-H activation path, leading to the alkyne insertion reaction. All complexes were characterized by 1H, 13C, and 11B NMR spectra as well as elemental analyses. Their structures were further confirmed by single-crystal X-ray analyses. © 2011 American Chemical Society.

Wei C.,Nankai University | Li Y.,Nankai University | Cai X.,Chinese University of Hong Kong
International Journal of Production Economics | Year: 2011

We consider an inventory and production planning problem with uncertain demand and returns, in which the product return process is integrated into the manufacturing process over a finite planning horizon. We first propose an inventory control model for the return and remanufacturing processes with consideration of the uncertainty of the demand and returns. Then a robust optimization approach is applied to deal with the uncertainty of the problem through formulating a robust linear programming model. Moreover, properties on the robust optimization model are studied, and an equivalent robust optimization model based on duality theory is obtained which allows the solutions to be derived more efficiently. Finally, we provide a set of numerical examples to verify the effectiveness of the approach and analyze the effects of the key parameters on the solutions. © 2009 Elsevier B.V. All rights reserved.

Li Y.,Nankai University | Wei C.,Yunnan Provincial Tobacco Monopoly Bureau | Cai X.,Chinese University of Hong Kong
International Journal of Production Economics | Year: 2012

We study optimal pricing and order policies in supply chain management of fashion products (e.g.; a fashion apparel category) with consideration of product returns between supply chain partners (B2B). In order to study channel performance and optimal policies, two stochastic models for centralized channel and decentralized channel are, respectively, developed to handle new fashion and off-season product sales. In the centralized channel, closed-form solutions for optimal order and pricing decisions are proposed for new fashion products. Further, in a decentralized channel, the Stackelberg game model is proposed to derive the optimal Stackelberg equilibrium solution, and then a buy-back contract is designed to coordinate the channel. We also perform parameter analysis on performance of the two channel models. Numerical analysis is finally presented to validate our theoretical results and compare channel performances. © 2011 Elsevier B.V. All Rights Reserved.

Ouyang T.,Brigham Young University | Yan D.,Nankai University
Celestial Mechanics and Dynamical Astronomy | Year: 2011

This paper gives an analytic proof of the existence of Schubart-like orbit, a periodic orbit with singularities in the symmetric collinear four-body problem. In each period of the Schubart-like orbit, there is a binary collision (BC) between the inner two bodies and a simultaneous binary collision (SBC) of the two clusters on both sides of the origin. The system is regularized and the existence is proved by using a "turning point" technique and a continuity argument on differential equations of the regularized Hamiltonian. © 2010 Springer Science+Business Media B.V.

Zhang X.Z.,Nankai University | Jin L.,Chinese University of Hong Kong | Song Z.,Nankai University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

Complex potential and non-Hermitian hopping amplitude are building blocks of a non-Hermitian quantum network. The appropriate configuration, such as a PT-symmetric distribution, can lead to a full real spectrum. To investigate the underlying mechanism of this phenomenon, we study the phase diagrams of semi-infinite non-Hermitian systems. They consist of finite non-Hermitian clusters and semi-infinite leads. Based on the analysis of the solutions of the concrete systems, it is shown that they can have full real spectra without any requirements on the symmetry, and the wave function within the leads becomes unidirectional plane waves at the exceptional point. This universal dynamical behavior is demonstrated as the persistent emission and reflectionless absorption of wave packets in typical non-Hermitian systems containing complex on-site potentials and non-Hermitian hopping amplitudes. © 2013 American Physical Society.

Li K.,Nankai University | Du T.C.,Chinese University of Hong Kong
Decision Support Systems | Year: 2012

Over the years, mobile advertising has grown to become a technology that allows an advertiser to promote products or services to targeted users efficiently and effectively. This is because the ubiquitous nature of mobile devices can provide contextual information and allow users to demonstrate preferences. This study proposes a targeted mobile advertising system (TMAS) that works as a platform to provide both merchants and consumers with context-aware advertisements. The approach integrates the advantages of both mobile and targeted advertising to allow merchants to disseminate location-based targeted advertisements while providing pull-type and personalized advertisements for consumers. To demonstrate the TMAS, we build a platform to provide highly relevant advertising to consumers and to guarantee that advertisements have an equal opportunity of being presented to consumers. © 2012 Elsevier B.V. All rights reserved.

Yao Q.,Nankai University | Moskowitz D.S.,McGill University
Journal of Personality | Year: 2015

The present study examined the influence of trait Agreeableness and its interaction with social role status on interpersonal correspondence as reflected in the within-person relation between a person's communal (agreeable-quarrelsome) behavior and perceptions of the interaction partner's communal behavior. We used a sample of working adults (original data set: 113 participants and 12,303 interpersonal events; constrained data set in the work setting: 109 participants and 3,193 interpersonal events) and an event-contingent recording procedure to assess behavior in naturalistic interpersonal events. The results of multilevel modeling indicated that interpersonal correspondence was lower for high trait Agreeableness persons than for low trait Agreeableness persons, apparently due to less responsiveness to more disagreeable behavior by the other person in an interaction. High Agreeableness persons manifest greater interpersonal correspondence when in a high-status role than when in a low-status role, apparently by increasing responsiveness to disagreeable behavior from others. The results imply that high social role status may influence the effortful control process of high trait Agreeableness persons over their behavioral reactions to others' disagreeable behavior during interpersonal interactions. © 2014 Wiley Periodicals, Inc.

Shan J.,Nankai University | Zhu K.,Chinese University of Hong Kong
Production and Operations Management | Year: 2013

With the outsourcing of manufacturing activities from Western countries, China has gradually become the global manufacturing hub. In the presence of increased competition from both inside and outside of China, many Chinese manufacturers have turned to scientific management approaches and implemented various enterprise systems. In academia, there has been a growing interest in quantifying the impacts of such efforts on the corporate performance of Chinese firms, and research has been carried out in areas such as finance and accounting. However, due to limited visibility of operational decisions and data, there seems to be a lack of investigation into the impacts on the firms' operational performance in the literature. In this article, we apply an empirical method to investigate the inventories of 1286 firms listed on the two stock exchanges in China, the Shanghai Stock Exchange and the Shenzhen Stock Exchange. We find that on average the inventory levels have declined over time and that the firm-level data is consistent with several implications derived from classical inventory models. © 2012 Production and Operations Management Society.

Li X.,Nankai University | Li Y.,Nankai University | Cai X.,Chinese University of Hong Kong
Computers and Operations Research | Year: 2015

Remanufacturing is creating considerable benefit to industry and community, but the uncertainties in both supply and demand sides bring significant difficulty to the production and marketing management of remanufactured products. This paper considers the remanufacturing and pricing decisions when both the remanufacturing yield and the demand for remanufactured products are random. Two typical sequential decision strategies are explored: First-Remanufacturing-Then-Pricing (FRTP) and First-Pricing-Then-Remanufacturing (FPTR). The optimal remanufacturing quantity and selling price of the remanufactured product are developed for each strategy, under negligible salvage value and shortage penalty. We also conduct a numerical study to investigate the scenario where the salvage value and shortage penalty are non-negligible, and explore the parameter sensitivity of the systems. We find that FRTP strategy is more preferable for low remanufacturing cost, market-price sensitivity, and variance of demand randomness, and for high shortage penalty, salvage value, and variance of remanufacturing yield; while FRTP strategy is more preferable for the complementary situation. © 2014 Elsevier Ltd. All rights reserved.

News Article | November 25, 2016
Site: globenewswire.com

SHENZHEN, China, Nov. 25, 2016 (GLOBE NEWSWIRE) -- Xunlei Limited (“Xunlei” or the “Company”) (Nasdaq:XNET), a leading cloud-based acceleration technology company in China, today announced the appointment of Mr. Tao Zou as a director of the Company and the resignation of Dr. Hongjiang Zhang as a director of the Company, due to his intended retirement, effective December 1, 2016. Mr. Tao Zou has been appointed as a director of the Company, replacing Dr. Zhang, effective December 1, 2016. Mr. Zou, who has worked at Kingsoft Corporation Limited (“Kingsoft”) and its subsidiaries for approximately twenty years, is currently an executive director and senior vice president of Kingsoft as well as the chief executive officer and a director of Seasun Holdings Limited, a subsidiary of Kingsoft. Mr. Zou has also been appointed as the chief executive officer of Kingsoft, effective December 1, 2016 and a director of certain subsidiaries of Kingsoft, such as Cheetah Mobile Inc. and Kingsoft Cloud Holdings, effective December 1, 2016. He graduated from Tianjin Nankai University in 1997. “We would like to thank Dr. Zhang for his valuable dedication and outstanding contributions over these years. We wish him the very best in all his future endeavors. We would also like to express our warmest welcome to Mr. Zou. We believe that Mr. Zou’s experience and industry expertise will bring significant value to Xunlei,” said Mr. Sean Shenglong Zou, Chairman and Chief Executive Officer of Xunlei. Xunlei Limited (“Xunlei”) is a leading cloud-based acceleration technology company in China. Xunlei operates a powerful internet platform in China based on cloud computing to provide users with quick and easy access to digital media content through its core products and services, Xunlei Accelerator and the cloud acceleration subscription services. Xunlei is increasingly extending into mobile devices in part through potentially pre-installed acceleration products in mobile phones. Benefitting from the large user base accumulated by Xunlei Accelerator, Xunlei has further developed various value-added services to meet a fuller spectrum of its users’ digital media content access and consumption needs. This press release contains statements of a forward-looking nature. These statements are made under the “safe harbor” provisions of the U.S. Private Securities Litigation Reform Act of 1995. You can identify these forward- looking statements by terminology such as “will,” “expects,” “believes,” “anticipates,” “future,” “intends,” “plans,” “believes,” “estimates” and similar statements. Among other things, the management’s quotations, as well as the Company’s strategic, operational and acquisition plans, contain forward-looking statements. These forward-looking statements involve known and unknown risks and uncertainties and are based on current expectations, assumptions, estimates and projections about the Company and the industry. Forward-looking statements involve inherent risks and uncertainties, including but not limited to: the Company’s ability to continue to innovate and provide attractive products and services to retain and grow its user base; the Company’s ability to keep up with technological developments and users’ changing demands in the Internet industry; the Company’s ability to convert its users into subscribers of its premium services; the Company’s ability to deal with existing and potential copyright infringement claims and other related claims; the Company’s ability to react to the governmental actions for its scrutiny of internet content in China and the Company’s ability to compete effectively. Although the Company believes that the expectations expressed in these forward-looking statements are reasonable, it cannot assure you that its expectations will turn out to be correct, and investors are cautioned that actual results may differ materially from the anticipated results. Further information regarding risks and uncertainties faced by the Company is included in the Company’s filings with the U.S. Securities and Exchange Commission. All information provided in this press release is as of the date of the press release, and the Company undertakes no obligation to update any forward-looking statements to reflect subsequent occurring events or circumstances, or changes in its expectations, except as may be required by law.

BEIJING, Dec. 01, 2016 (GLOBE NEWSWIRE) -- 21Vianet Group, Inc. (Nasdaq:VNET) ("21Vianet" or the "Company"), a leading carrier-neutral internet data center services provider in China, today announced that Dr. Hongjiang Zhang, an independent director of the Company as well as a member of the Compensation Committee, has resigned from his current positions effective December 1, 2016. Dr. Zhang has served as the Company’s director since January 2015. The Board of Directors (the “Board”) has appointed Mr. Tao Zou as a new independent director to the Company, and Mr. Erhfei Liu, who has served as an independent director since May 2015, will replace Dr. Zhang as a member of the Compensation Committee, both effective on Dec 1, 2016. Mr. Tao Zou is currently the Chief Executive Officer and an executive director of Kingsoft Corporation Limited ("Kingsoft"), a company listed on the Hong Kong Stock Exchange (Stock Code:3888) and the Chief Executive Officer and one of the directors of Seasun Holdings Limited, overseeing the operations of Seasun Holdings Limited and its subsidiaries, including the research and development of online games, and the operations of the gaming business of Kingsoft and its subsidiaries ("Kingsoft Group"). Mr. Zou joined Kingsoft Group in 1998 and has taken various positions within the Kingsoft Group since then. Mr. Zou received a bachelor’s degree from Tianjin Nankai University. Mr. Steve Zhang, Chief Executive Officer of the Company, stated, “We are very pleased to have Mr. Zou join our Board and we look forward to his contributions. His extensive industry knowledge and managerial experience with Kingsoft Group will be invaluable to 21Vianet and our customers in this rapidly growing internet industry. Furthermore, I would like to thank Dr. Zhang for his hard work over the past two years with the firm. We all appreciate his leadership and wish him great success in his future endeavors.” 21Vianet Group, Inc. is a leading carrier-neutral Internet data center services provider in China. 21Vianet provides hosting and related services, managed network services, cloud services, content delivery network services, last-mile wired broadband services and business VPN services, improving the reliability, security and speed of its customers' Internet infrastructure. Customers may locate their servers and networking equipment in 21Vianet's data centers and connect to China's Internet backbone through 21Vianet's extensive fiber optic network. In addition, 21Vianet's proprietary smart routing technology enables customers' data to be delivered across the Internet in a faster and more reliable manner. 21Vianet operates in more than 30 cities throughout China, servicing a diversified and loyal base of more than 2,000 hosting enterprise customers that span numerous industries ranging from Internet companies to government entities and blue-chip enterprises to small- to mid-sized enterprises. This announcement contains forward-looking statements. These forward-looking statements are made under the "safe harbor" provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements can be identified by terminology such as "will," "expects," "anticipates," "future," "intends," "plans," "believes," "estimates" and similar statements. Among other things, quotations from management in this announcement as well as 21Vianet's strategic and operational plans contain forward-looking statements. 21Vianet may also make written or oral forward-looking statements in its reports filed with, or furnished to, the U.S. Securities and Exchange Commission, in its annual reports to shareholders, in press releases and other written materials and in oral statements made by its officers, directors or employees to third parties. Statements that are not historical facts, including statements about 21Vianet's beliefs and expectations, are forward-looking statements. Forward-looking statements involve inherent risks and uncertainties. A number of factors could cause actual results to differ materially from those contained in any forward-looking statement, including but not limited to the following: 21Vianet's goals and strategies; 21Vianet's expansion plans; the expected growth of the data center services market; expectations regarding demand for, and market acceptance of, 21Vianet's services; 21Vianet's expectations regarding keeping and strengthening its relationships with customers; 21Vianet's plans to invest in research and development to enhance its solution and service offerings; and general economic and business conditions in the regions where 21Vianet provides solutions and services. Further information regarding these and other risks is included in 21Vianet's reports filed with, or furnished to, the Securities and Exchange Commission. All information provided in this press release and in the attachments is as of the date of this press release, and 21Vianet undertakes no duty to update such information, except as required under applicable law.

Zhu Y.-P.,Nankai University | Ma T.-Y.,Nankai University | Liu Y.-L.,Nankai University | Ren T.-Z.,Hebei University of Technology | Yuan Z.-Y.,Nankai University
Inorganic Chemistry Frontiers | Year: 2014

Metal phosphonate materials are promising non-siliceous inorganic-organic hybrids that are synthesized by combining metal joints and organophosphonic linkages at the molecular scale. The mild conditions for metal phosphonate synthesis, their homogeneous composition and the combined merits of inorganic units and organic groups have permitted the rational design and incorporation of various functionalities through constituent building units. In this critical review, we present the development and recent advances related to the field of metal phosphonates and the relevant nanocomposites. The possibility to integrate the functionalities from both inorganic and organic moieties is discussed. The incorporation of well-defined porosity and capacity for post-modification have extended the application potential to the area of adsorption, separation, catalysis, environmental intervention, energy storage and biology. Metal phosphonates thus present an unprecedented opportunity for the rational and precise design of sophisticated materials with multifunctionality. © 2014 the Partner Organisations.

He X.,Hong Kong Polytechnic University | He X.,Fudan University | Liu Z.-B.,Hong Kong Polytechnic University | Liu Z.-B.,Nankai University | Wang D.N.,Hong Kong Polytechnic University
Optics Letters | Year: 2012

We demonstrate a wavelength-tunable, passively mode-locked erbium-doped fiber laser based on graphene and chirped fiber Bragg grating. The saturable absorber used to enable passive mode-locking in the fiber laser is a section of microfiber covered by graphene film, which allows light-graphene interaction via the evanescent field of the microfiber. The wavelength of the laser can be continuously tuned by adjusting the chirped fiber Bragg grating, while maintaining mode-locking stability. Such a system has high potential in tuning the mode-locked laser pulses across a wide wavelength range. © 2012 Optical Society of America.

Zhang X.-X.,Nankai University | Zhang X.-X.,Humboldt University of Berlin | Liang M.,Pennsylvania State University | Ernsting N.P.,Humboldt University of Berlin | Maroncelli M.,Pennsylvania State University
Journal of Physical Chemistry Letters | Year: 2013

It was shown recently that a simple dielectric continuum model predicts the integral solvation time of a dipolar solute âŸ̈τ solv⟩ to be inversely proportional to the electrical conductivity σ0 of an ionic solvent or solution. In this Letter, we provide a more general derivation of this connection and show that available data on coumarin 153 (C153) in ionic liquids generally support this prediction. The relationship between solvation time and conductivity can be expressed by ln(âŸ̈τsolv⟩/ps) = 4.37 - 0.92 ln (σ0/S m-1) in 34 common ionic liquids. © 2013 American Chemical Society.

Zhou X.-H.,Nankai University | Zhou X.-H.,Tianjin Bohai Vocational Technical College | Kong D.-M.,Nankai University | Shen H.-X.,Nankai University
Analytical Chemistry | Year: 2010

Some G-quadruplex - hemin complexes are DNAzyme peroxidases that efficiently catalyze H2O2-mediated reactions, such as the oxidation of ABTS (2,2′-azinobis(3-ethylbenzothiozoline)-6-sulfonic acid) by H2O2. Since Ag+ chelates guanine bases at the binding sites are involved in G-quadruplex formation, the presence of Ag+ may disrupt these structures and inhibit the peroxidase activity of G-quadruplex - hemin DNAzymes. On the basis of this principle, a highly sensitive and selective Ag+-detection method was developed. The method allows simple detection of aqueous Ag+ with a detection limit of 64 nM and a linear range of 50-3000 nM. Cysteine (Cys) is a strong Ag +-binder and competes with quadruplex-forming G-rich oligonucleotides for Ag+-binding, promoting the reformation of Gquadruplexes and increasing their peroxidase activity. Therefore, the Ag+-sensing system was also developed as a Cys-sensing system. This "turn-on" process allowed the detection of Cys at concentrations as low as 50 nM using a simple colorimetric technique. The Cyssensing system could also be used for the detection of reduced glutathione (GSH). Neither the Ag+-Sensing nor the Cys-sensing systems required labeled oligonucleotides. In addition, both gave large changes in absorbance signal that could be observed by the naked eye. Thus, a simple visual method for Ag+- or Cysdetection was developed. © 2010 American Chemical Society.

An L.,Nankai University | Tong L.,Hebei University of Technology
Knowledge-Based Systems | Year: 2010

Rough sets theory has proved to be a useful mathematical tool for dealing with the vagueness and granularity in information tables. Classical definitions of lower and upper approximations were originally introduced with reference to an indiscernibility relation. However, indiscernibility relation is still restrictive for many applications. Many real-world problems deal with assignment of some objects to some preference-ordered decision classes. And, the objects are described by a finite set of qualitative attributes and quantitative attributes. In this paper, we construct the indiscernibility relation for the subset of nominal attributes, the outranking relation for the subset of ordinal attributes, and the similarity relation for the subset of quantitative attributes. Then the global binary relation is generated by the intersection of indiscernibility relation, outranking relation and similarity relation. New definitions of lower and upper approximations of the upward and downward unions of decision classes are proposed based on the global relation. We also prove that the lower and upper approximation operations satisfy the properties of rough inclusion, complementarity, identity of boundaries, and monotonicity. © 2010 Elsevier B.V. All rights reserved.

Wang Y.-Q.,Nankai University | He X.-W.,Nankai University | Li W.-Y.,Nankai University | Zhang Y.-K.,Nankai University | Zhang Y.-K.,CAS Dalian Institute of Chemical Physics
Journal of Materials Chemistry C | Year: 2013

We fabricated QD-silica-Au NC hybrid spheres, in which the solid silica core contained QDs while the mesostructured silica shell contained Au NCs, by a two-step synthesis procedure. The hybrid spheres were further characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and nitrogen adsorption-desorption analysis to confirm the formation of the ternary hybrid structure. The as-prepared ternary hybrid spheres showed an interesting fluorescence spectrum variation and further could be developed as a precursor for fabricating multicolor fluorescence bar codes by using l-cysteine (l-Cys) as an effective post-encoding adjuster. A small variation of the concentration of l-Cys led to a prominent change of the precursor's fluorescence intensity ratio, which could correspond to a series of distinguishable multicolor fluorescent bar codes. Furthermore, the multicolour fluorescence bar codes fabricated by the post-encoding method showed excellent non-reversibility, batch-to-batch reproducibility of the intensity ratios, photophysical and thermal stability properties and anti-interference capabilities, which are important virtues for them to be used in high-throughput bio-labelling and imaging. © 2013 The Royal Society of Chemistry.

Li D.,CAS Dalian Institute of Chemical Physics | Li D.,Nankai University | Wang Y.,CAS Dalian Institute of Chemical Physics | Han K.,CAS Dalian Institute of Chemical Physics
Coordination Chemistry Reviews | Year: 2012

Cytochrome P450 (P450) enzymes are the major catalysts involved in the oxidative metabolism of most drugs, steroids, carcinogens, and other chemicals. They catalyze a variety of reactions and convert chemicals to potentially reactive products as well as make compounds less toxic. More than 75% of drugs in clinical use are metabolized by P450s. Understanding the mechanism of drug metabolism by P450, in particular the chemical process, is indispensable in the early phases of drug discovery process. In this review, we discuss our recent theoretical studies on the mechanism of some specific compounds catalyzed by P450. Density functional theory (DFT) is used as the quantum mechanical (QM) tool to explore the fundamental mechanism of these reactions. These DFT calculations provide structures, energies, and some other properties of transition states and intermediates and thus shed light on the electronic factors that govern the stability and reactivity. These theoretical studies provide a complementary insight to experiment and suggest some new features. DFT serves a powerful tool to explore the chemical mechanism of drug metabolism by P450. The revealed fundamental mechanism concerning how the enzyme catalyzes the drug metabolism, especially the transition state of the rate-determining reaction step, could provide a valuable mechanistic base for rational design of novel drugs. © 2012 Elsevier B.V.

Zhu Y.-P.,Nankai University | Liu Y.-L.,Nankai University | Ren T.-Z.,Hebei University of Technology | Yuan Z.-Y.,Nankai University
Nanoscale | Year: 2014

Hollow manganese phosphonate microspheres of an inorganic-organic hybrid with hierarchically porous shells were prepared through a template-free hydrothermal method using ethylene diamine tetra(methylene phosphonic acid) as the coupling molecule. The hollow structures with hierarchical porosity were confirmed by SEM, TEM and N2 sorption. FT-IR, XPS and TG-DSC measurements revealed that the organophosphonate linkers were homogeneously incorporated into the hybrid framework. The hierarchical manganese phosphonates could be used as efficient adsorbents for the removal of copper ions, showing fast binding kinetics due to the well-structured porosity. The adsorption process follows pseudo-second order reaction kinetics, as well as Langmuir isotherm, indicating that Cu2+ was monolayer adsorbed on the hybrid by chemical complexation. Furthermore, the synthesized manganese phosphonates with peculiar porosity exhibited excellent size selectivity for protein adsorption in a complex solution, presenting the promising potential as candidates for biomaterials. © The Royal Society of Chemistry 2014.

Zhang X.-X.,Nankai University | Zhang X.-X.,Humboldt University of Berlin | Liang M.,Pennsylvania State University | Ernsting N.P.,Humboldt University of Berlin | Maroncelli M.,Pennsylvania State University
Journal of Physical Chemistry B | Year: 2013

The dynamic Stokes shift of coumarin 153, measured with a combination of broad-band fluorescence upconversion (80 fs resolution) and time-correlated single photon counting (to 20 ns), is used to determine the complete solvation response of 21 imidazolium, pyrrolidinium, and assorted other ionic liquids. The response functions so obtained show a clearly bimodal character consisting of a subpicosecond component, which accounts for 10-40% of the response, and a much slower component relaxing over a broad range of times. The times associated with the fast component correlate with ion mass, confirming its origins in inertial solvent motions. Consistent with many previous studies, the slower component is correlated to solvent viscosity, indicating that its origins lie in diffusive, structural reorganization of the solvent. Comparisons of observed response functions to the predictions of a simple dielectric continuum model show that, as in dipolar solvents, solvation and dielectric relaxation involve closely related molecular dynamics. However, in contrast to dipolar solvents, dielectric continuum predictions systematically underestimate solvation times by factors of at least 2-4. © 2012 American Chemical Society.

Zhang M.,Nankai University | Zhang X.,Nankai University | He X.,Nankai University | Chen L.,Nankai University | And 2 more authors.
Nanoscale | Year: 2012

In this study, we report a facile method for the preparation of core-shell magnetic molecularly imprinted polymers (MIPs) for protein recognition. Uniform carboxyl group functionalized Fe 3O 4 nanoparticles (NPs) were synthesized using a solvothermal method. Magnetic MIPs were synthesized by self-polymerization of dopamine in the presence of template protein on the surface of the Fe 3O 4 NPs. A thin layer of polydopamine can be coated on Fe 3O 4 NPs via dopamine self-polymerization and the imprinted polydopamine shells can be controlled by the mass ratio of Fe 3O 4 NPs and dopamine. More importantly, there is a critical value of polydopamine shell thickness for the maximum rebinding capacity. The as-prepared lysozyme-imprinted Fe 3O 4@polydopamine NPs show high binding capacity and acceptable specific recognition behavior towards template proteins. This method provides the possibility for the separation and enrichment of abundant proteins in proteomic analysis. © 2012 The Royal Society of Chemistry.

Song X.,Nankai University | Yang Y.,Hebei University of Technology | Liu J.,Nankai University | Zhao H.,Nankai University
Langmuir | Year: 2011

Exfoliated graphene oxide (GO) sheets with hydrophilic functional groups on the surface were prepared by the oxidation of graphite. Because of the hydrophilic groups on the sheets and the hydrophobic carbon surface, GO sheets were located at the oil-water interface and could be used as a stabilizer in Pickering emulsions. After the Pickering emulsion polymerization of styrene, PS colloidal particles with GO sheets on the surface were prepared. The size of the GO sheets exerts an important influence on the preparation of PS colloidal particles. Small GO sheets located at the liquid-liquid interface and GO-stabilized PS colloidal particles were prepared; however, for large GO sheets, smaller PS colloidal particles prepared on the GO surface were observed. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and morphology of the colloidal particles. TEM, SEM, and XPS results all suggest the successful preparation of GO-stabilized PS colloidal particles. © 2010 American Chemical Society.

Zhang W.,Nankai University | He X.-W.,Nankai University | Li W.-Y.,Nankai University | Zhang Y.-K.,Nankai University | Zhang Y.-K.,CAS Dalian Institute of Chemical Physics
Chemical Communications | Year: 2012

A thermo-sensitive imprinted polymer coating CdTe quantum dots was developed to prepare fluorescent thermo-sensitive protein-affinity materials, which exhibited high specific recognition ability towards target proteins. © 2012 The Royal Society of Chemistry.

Zhu Y.-P.,Nankai University | Ren T.-Z.,Hebei University of Technology | Yuan Z.-Y.,Nankai University
RSC Advances | Year: 2015

Periodic mesoporous aluminum phosphonate (PMAP) materials with homogeneously integrated organophosphonate bridging groups inside the hybrid framework were synthesized by an autoclaving process using ethylene diamine tetra(methylene phosphonic acid) as the coupling molecule, with the assistance of the cationic surfactant cetyltrimethylammonium bromide. The prepared aluminum phosphonates possessed a high specific surface area of 511 m2 g-1 and a typical hexagonal mesophase, thus guaranteeing the considerable uptake capacity for loading Co2+ ions through coordination interaction. The monolayered adsorption behavior of Co2+ was confirmed, and the Co2+-loaded PMAP could be further utilized as a heterogeneous catalyst for oxidizing decomposition of phenol in the presence of peroxymonosulfate, with favorable kinetic and thermodynamic characteristics. It is suggested that the functionalities of metal phosphonate organic-inorganic hybrids could be rationally designed by judiciously selecting precursors and post-modification, making them potentially applicable in environmental remediation and catalysis. © 2015 The Royal Society of Chemistry.

Zhu Y.-P.,Nankai University | Ren T.-Z.,Hebei University of Technology | Yuan Z.-Y.,Nankai University
New Journal of Chemistry | Year: 2014

Recent progress in mesoporous materials has been extended to chemically designed non-siliceous inorganic-organic hybrid materials including metal phosphonates, carboxylates and sulfonates. Well-defined mesoporosity, mesophase and micro-/macroscopic morphology can be successfully obtained and effectively adjusted by the judicious control of the synthesis systems. A considerable amount of organic functional groups can be homogeneously integrated in the hybrid framework through facilely employing various organic coupling molecules, exhibiting the pristine functionalities and the potentials of being further modified. This has resulted in multifunctional porous materials with particular and novel properties, and has broadened their application region beyond the traditional use as catalysts and adsorbents, as they can even contribute to the developments in fields ranging from energy storage and conversion to medical diagnosis and therapy. © 2014 The Partner Organisations.

Chen X.,Nankai University | Dai W.,Central University of Finance and Economics
International Journal of Fuzzy Systems | Year: 2011

The concept of uncertain entropy is used to provide a quantitative measurement of the uncertainty associated with uncertain variables. After introducing the definition, this paper gives some examples of entropy of uncertain variables. Furthermore this paper proposes the maximum entropy principle for uncertain variables, that is, out of all the uncertainty distributions satisfying given constraints, to choose the one has maximum entropy. © 2011 TFSA.

Wang Y.,Temple University | Deng X.,Temple University | Mancarella S.,Temple University | Hendron E.,Temple University | And 4 more authors.
Science | Year: 2010

Calcium signals, pivotal in controlling cell function, can be generated by calcium entry channels activated by plasma membrane depolarization or depletion of internal calcium stores. We reveal a regulatory link between these two channel subtypes mediated by the ubiquitous calcium-sensing STIM proteins. STIM1 activation by store depletion or mutational modification strongly suppresses voltage-operated calcium (CaV1.2) channels while activating store-operated Orai channels. Both actions are mediated by the short STIM-Orai activating region (SOAR) of STIM1. STIM1 interacts with CaV1.2 channels and localizes within discrete endoplasmic reticulum/plasma membrane junctions containing both CaV1.2 and Orai1 channels. Hence, STIM1 interacts with and reciprocally controls two major calcium channels hitherto thought to operate independently. Such coordinated control of the widely expressed CaV1.2 and Orai channels has major implications for Ca 2+ signal generation in excitable and nonexcitable cells.

Zhou M.,Nankai University | Wang H.,Nankai University | Hassett D.J.,University of Cincinnati | Gu T.,Ohio University
Journal of Chemical Technology and Biotechnology | Year: 2013

Bioenergy is a renewable energy that plays an indispensable role in meeting today's ever increasing energy needs. Unlike biofuels, microbial fuel cells (MFCs) convert energy harvested from redox reactions directly into bioelectricity. MFCs can utilize low-grade organic carbons (fuels) in waste streams. The oxidation of the fuel molecules requires biofilm catalysis. In recent years, MFCs have also been used in the electrolysis mode to produce bioproducts in laboratory tests. MFCs research has intensified in the past decade and the maximum MFCs power density output has been increased greatly and many types of waste streams have been tested. However, new breakthroughs are needed for MFCs to be practical in wastewater treatment and power generation beyond powering small sensor devices. To reduce capital and operational costs, simple and robust membrane-less MFCs reactors are desired, but these reactors require highly efficient biofilms. Newly discovered conductive cell aggregates, improved electron transport through hyperpilation via mutation or genetic recombination and other advances in biofilm engineering present opportunities. This review is an update on the recent advances on MFCs designs and operations. © 2012 Society of Chemical Industry.

Zhang X.,Nankai University | Liu J.,Hebei University of Technology
Journal of Agricultural and Food Chemistry | Year: 2011

The effect of arabic gum (AG) and xanthan gum (XG) on the physicochemical properties of 2% pesticide avermyctin in water emulsions was systematically investigated by measuring creaming stability, droplet size, zeta potential, and rheology. Addition of AG and XG had significant influence on the physicochemical properties of emulsions. Emulsions showed high stability throughout the storage time in the AG concentration range of 0-0.14%. In contrast, addition of XG induced the apparent creaming of emulsion as the XG concentration increased from 0.011 to 0.15%, which might be well explained by the depletion flocculation of droplets. The droplet diameter increased progressively with increasing AG concentration; however, it sharply grew initially with XG concentration and reached a maximum, followed by a gradual decrease. Zeta potential increased gradually as AG concentration was lower than 0.081%, followed by a slight decrease, whereas it reduced dramatically as XG concentration increased from 0.011 to 0.040% and then remained almost unchanged. In the AG concentration range of 0-0.14%, the emulsion exhibited typical Newtonian flow behavior and the viscosity decreased a little. The XG emulsion exhibited Newtonian flow behavior at low XG concentrations (′0.019%), whereas, non-Newtonian flow behavior was displayed at relatively high XG concentrations (>0.019%), wherein viscosity value and yield value increased gradually as XG concentration increased. In addition, the curves of shear stress versus shear rate for XG emulsion and solution were well fitted by a power law model and the Herschel-Bulkley model; the Herschel-Bulkley model fitted much better. The present study would provide useful information for the reasonable application of AG and XG in making stable pesticide emulsion. © 2011 American Chemical Society.

Zhou W.,Nankai University | Gao X.,Nankai University | Liu D.,Nankai University | Chen X.,U.S. National Institutes of Health
Chemical Reviews | Year: 2015

Gold nanoparticles (AuNP)-based in-vitro diagnostics (IVDs) have drawn considerable research interest because of their distinct physical and optical properties, including localized surface plasmon resonance (LSPR), fluorescence resonance energy transfer (FRET), surface enhanced Raman scattering (SERS), nonlinear optical properties, and quantized charging effect. The size, shape, aggregation state, and surface properties of AuNPs can be finely tuned, which is highly important in creating chemical and biological sensors. AuNPs modified with specific antibodies can recognize their antigens via immune-reaction, causing the local environment changes of the nanoparticles and resulting in a peak shift in the LSPR spectrum. AuNP-based biobarcode assay was also employed to detect target DNA. The DNA biobarcode assay was designed by replacing the antibodies on magnetic microparticles and AuNPs in the protein detection system with specific ssDNAs. To bring the AuNP-based IVD assays into real clinical applications, it is highly desirable to prepare extremely reproducible AuNP probes to achieve reproducible detection signals. It is critical to simplify the procedures of synthesis and functionalization of probes to minimize the variation in different batches.

Zhang Z.-J.,Nankai University | Han M.,Nankai University | Han M.,Traditional Chinese Medicine Research and Development Institute of Tasly Academy | Zhang H.-Y.,Nankai University | Liu Y.,Nankai University
Organic Letters | Year: 2013

A double-leg elevator with an electron-rich anthracene moiety at the platformlike component and an electron-deficient naphthalenediimide unit in the middle of a double-leg riglike component was prepared through "click chemistry", in which the reversible elevator movement between different levels could be controlled upon the addition of base and acid. © 2013 American Chemical Society.

Zhang X.,Nankai University | He X.,Nankai University | Chen L.,Nankai University | Zhang Y.,Nankai University | Zhang Y.,CAS Dalian Institute of Chemical Physics
Journal of Materials Chemistry | Year: 2012

In this study, a novel approach was developed to synthesize aminophenylboronic acid functionalized magnetic nanoparticles (NPs) via Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) 'click' chemistry. Firstly, azide-functional Fe 3O 4 NPs were obtained by a two-step chemical modification process. Then, an alkyne-phenylboronic acid molecule was connected onto the surface of magnetite by the CuAAC reaction. The morphology, structure and composition of the synthesized nanocomposites were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectrometry (XPS). Five proteins, including ovalbumin (OB), transferrin (Trf), as glycoprotein templates and lysozyme (Lyz), bovine serum albumin (BSA), horse heart cytochrome c (Cyt C) as nonglycoprotein templates are chosen as target proteins. The as-prepared click-Fe 3O 4@APBA NPs with a mean diameter of 23.2 nm showed a strong magnetic response to an externally applied magnetic field and exhibited a high adsorption capacity and excellent specificity towards glycoproteins in comparison with nonglycoproteins. The click-Fe 3O 4@APBA NPs showed the higher adsorption capacity towards glycoproteins than the nonclick-Fe 3O 4@APBA NPs which were synthesized through a common nucleophilic substitution reaction. The greatly enhanced adsorption capacity towards glycoproteins demonstrated that the 'click' method presented great superiority in ligand immobilization. Finally, the click-Fe 3O 4@APBA NPs could efficiently enrich glycoproteins from real egg white samples as well. © The Royal Society of Chemistry 2012.

News Article | August 22, 2016
Site: phys.org

A group of researchers from Nankai University in China, the University of Pittsburgh, and The Pennsylvania State University have demonstrated, for the first time, a synthetic mechanism for N-unsubstituted benzazetidines that is high yielding and practical. Their synthetic strategy can be used to make a variety of benzazetidine-based compounds for possible drug design exploration. Their work appears in Nature Chemistry. Researchers have made headway in nitrogen-based heterocycle chemistry using a palladium-catalyzed intramolecular dehydrogenative C-H amination (IDCA) reaction. In this reaction, the oxidized palladium catalyst coordinates to the target carbon and the amine. Ideally, this would result in a reductive elimination reaction in which the palladium is reduced back to its original oxidation state and the dehydrogenated carbon and amine would form a ring-closing bond. However, in practice, this reaction is difficult to accomplish in high yields. Four-membered rings are hindered due to ring strain. This leads to side products that are more thermodynamically favored than forming the four-membered ring. Gang He, Gang Lu, Zhengwei Guo, Peng Liu, and Gong Chen have devised a synthetic scheme that results in the desired benzazetidine using N-benzyl-picolinamide (PAs) as the reactant and Pd(OAc) as the catalyst. Key to the success of their synthetic scheme is rigid ligand structures both from the N-benzyl-picolinamide and the oxidant. They developed the phenyl-iodonium dimethylmalonate (PhI(DMM)) as their oxidant after seeing that PhI(OAc) , which is known to promote C-H acetoxylation using similar starting materials, formed a small amount of their target benzazetidine. However, the C-N ring closing reaction is thermodynamically unfavored compared to forming a C-OAc bond. After looking at computational studies to see how they could prevent the carbon-oxygen bond from forming, they decided to tether the oxygen on the carbonyl of the acetate to prevent it from reacting with the target carbon atom for the reductive elimination. After trying several tethers, they landed upon PhI(DMM), which proved to enhance the yield of the desired benzazetidine (48%). The next step was to see if this reaction was generalizable by changing the R group on the N-benzyl picolinamide reactant. Even in cases where the benzazetidine product could be formed using PhI(OAc) , He, et al. saw better yields with PhI(DMM). Furthermore, their reaction worked with a variety of functional groups, although, interestingly, did not work for unsubstituted benzylamine. An additional advantage of their scheme is that the PA protecting group was easily removed with sodium hydroxide in methanol, THF, and water at room temperature. He, et al. conducted mechanistic studies in hopes of understanding the reaction better so that it may be optimized for later research,. They found that the transition state involves a bimetallic Pd(III)/Pd(III) complex instead of a monomeric Pd(IV) compound. It is this bimetallic complex with the PhI(DMM) tether that promotes the desired reductive elimination pathway and blocks the C-OAc bond from forming. This research opens the door to the possibility of finding pharmaceuticals that involve a benzazetidine. This synthetic mechanism is versatile for various functional groups and, using the PhI(DMM) oxidizing agent, produces product yields that make this reaction pathway significantly more practical than the limited reaction mechanisms that were previously used to make benzazetidines. More information: Gang He et al. Benzazetidine synthesis via palladium-catalysed intramolecular C−H amination, Nature Chemistry (2016). DOI: 10.1038/nchem.2585 Abstract Small-sized N-heterocycles are important structures in organic synthesis and medicinal chemistry. Palladium-catalysed intramolecular aminations of the C−H bonds of unfunctionalized amine precursors have recently emerged as an attractive new method for N-heterocycle synthesis. However, the way to control the reactivity of high-valent Pd intermediates to form the desired C−N cyclized products selectively remains poorly addressed. Herein we report a strategy to control the reductive elimination (RE) pathways in high-valent Pd catalysis and apply this strategy to achieve the synthesis of highly strained four-membered benzazetidines via the Pd-catalysed intramolecular C−H amination of N-benzyl picolinamides. These reactions represent the first practical synthetic method for benzazetidines and enable access to a range of complex benzazetidines from easily obtainable starting materials. The use of a newly designed phenyliodonium dimethylmalonate reagent is critical, as oxidation of Pd(II) palladacycles with this reagent favours a kinetically controlled C−N RE pathway to give strained ring-closed products.

News Article | February 15, 2017
Site: cen.acs.org

Chemistry textbook authors may soon have to rewrite sections covering noble gases and chemical inertness. An international research team has reported the synthesis of a helium-sodium compound that’s stable at high pressures (Nat. Chem. 2017, DOI: 10.1038/nchem.2716). Helium’s best known feature is its unwillingness to react. With a stable closed-shell electron configuration, zero electron affinity, and an ionization energy that is higher than that of all other elements, helium defines chemical inertness. To examine the scope of the element’s low reactivity, scientists have searched for years—theoretically and experimentally—for helium-containing molecules. But they have turned up very little: for example, unusual species such as the HeH+ radical, which is stable only in its charged form, and HHeF, a metastable compounds. In contrast, helium’s noble gas cousins xenon and krypton long ago showed themselves capable of forming a variety of stable compounds. Still, a team of researchers that includes Artem R. Oganov of Skolkovo Institute of Science & Technology and Hui-Tian Wang and Xiang-Feng Zhou of Nankai University continued searching for stable helium compounds. They used a computational strategy known as evolutionary structure prediction to scan the helium-sodium interaction landscape over an enormous range of pressures. The team concluded that Na He should be thermodynamically stable at pressures greater than roughly 115 GPa, which is about 1 million times as high as Earth’s atmospheric pressure. Then they used a diamond anvil cell to achieve this type of pressure and synthesized the compound. On the basis of X-ray diffraction and other methods, the team reports that Na He adopts a structure similar to that of the mineral fluorite and is electrically insulating. The material, which remains stable up to at least 1,000 GPa, is an electride—a type of crystal containing positively charged ionic cores and electrons that function as anions. The researchers also found that Na HeO, which they have not yet prepared, should be stable at pressures greater than 15 GPa. “This study highlights how high pressure can be used to access compounds with novel stoichiometries and electronic structures,” says Eva Zurek, a specialist in computational chemistry at the University at Buffalo, SUNY. Na He would never be stable under atmospheric conditions, she says, but it has been synthesized in this study at roughly 40% of the pressure present at Earth’s center. The findings broaden understanding of chemical processes that may occur at great pressures inside gas giants such as Jupiter and Saturn. Lund University inorganic chemist Sven Lidin remarks that the implications for astronomy are clearly interesting, “but regarding our perception of chemical reactivity, this is a textbook changer.” Earlier discoveries of other noble gas compounds made it clear that inertness is a question of reaction conditions, Lidin says. But helium has been a holdout even under extreme conditions because it clings to its inner-shell electrons tightly and will not let go. These new findings, he adds, show that in some ways, “the last bastion of inertness has finally fallen.”

Chen G.-Y.,Nankai University | Song F.,Nankai University | Wang H.-T.,Nankai University | Wang H.-T.,Nanjing University
Optics Letters | Year: 2013

The focal electric fields for a 4π high numerical aperture (NA) focusing system with both the doughnut and higherorder Laguerre-Gaussian (LG) radially polarized (RP) beams are investigated in the case of NA 1, and the full width at half-maximum values of the focal spots are calculated. Compared with the single-lens high NA focusing configuration, a sharper spot, whose size is reduced efficiently in the transverse as well as the axial direction, can be formed. Such size reduction is attributed to not only the destruction interference of the longitudinal component caused by the π phase shift between any two adjacent rings of the incident higher-order LG RP beam coming from one particular direction but also the perfect destruction interference of the radial component formed by the two counter-propagating incident beams. © 2013 Optical Society of America.

Li X.,CAS Beijing National Laboratory for Molecular | Xi Z.,Nankai University | Luo S.,CAS Beijing National Laboratory for Molecular | Cheng J.-P.,Nankai University
Advanced Synthesis and Catalysis | Year: 2010

A highly enantioselective Michael addition of 3-substituted benzofuran-2(3H)-ones to chalcones catalyzed by a chiral bifunctional thiourea was developed. Several chiral 3,3′-substituted benzofuran-2(3H)-ones derivatives, bearing adjacent quaternary-tertiary stereocenters, were efficiently synthesized with excellent enantioselectivities. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

A novel cascade carbo-carbonylation reaction of unactivated arylalkenes with ketones or aldehydes was catalyzed by an organocatalyst and a transition metal catalyst via a SOMO-enamine under air, affording a simple approach to γ-diketones and γ-carbonyl aldehydes. © The Royal Society of Chemistry 2010.

Xia W.,Nanjing University | Hu X.-Y.,Nanjing University | Chen Y.,Nankai University | Lin C.,Nanjing University | Wang L.,Nanjing University
Chemical Communications | Year: 2013

A novel and highly stable inclusion complex was formed between per-butylated pillar[6]arene and a ferrocenium cation, while the reduced form ferrocene only showed extremely weak binding affinity with per-butylated pillar[6]arene in organic solvents. This journal is © The Royal Society of Chemistry 2013.

Xu B.,Nankai University | Zhu S.-F.,Nankai University | Zhang Z.-C.,Nankai University | Yu Z.-X.,CAS Beijing National Laboratory for Molecular | And 2 more authors.
Chemical Science | Year: 2014

The first highly enantioselective S-H bond insertion reaction was developed by cooperative catalysis of dirhodium(ii) carboxylates and chiral spiro phosphoric acids (SPAs) under mild and neutral reaction conditions with fast reaction rates, high yields (77-97% yields), and excellent enantioselectivities (up to 98% ee). The catalytic S-H bond insertion reaction provides a highly efficient method for the synthesis of chiral sulfur-containing compounds and advances the synthesis of a chiral sulfur-containing drug (S)-Eflucimibe. A systematic 31P NMR study revealed that no ligand exchange between dirhodium(ii) carboxylates and SPAs occurred in the reaction. The distinct behaviors of cooperative catalysts Rh2(TPA)4/(R)-1a and the prepared complex Rh2(R-1a)4 observed by in situ FT-IR spectroscopy excluded the feasibility of Rh2(R-SPA)4 being the real catalyst. DFT calculations showed that the activation barrier in the proton shift step became remarkably low as promoted by SPAs. Based on the experimental results and the calculations, the SPA was proposed as a chiral proton shuttle for the proton shift in reaction. Additionally, the single crystal structures of several SPAs were measured and used to rationalize the configurations of the S-H insertion products obtained in the reactions. The rigid and crowded environment around the SPAs ensures the high enantioselectivity in the S-H bond insertion reaction. © 2014 The Royal Society of Chemistry.

Sun C.-L.,CAS Beijing National Laboratory for Molecular | Sun C.-L.,Chinese Academy of Sciences | Sun C.-L.,Nankai University | Shi Z.-J.,CAS Beijing National Laboratory for Molecular | And 2 more authors.
Chemical Reviews | Year: 2014

Recent advances on the transition-metal-free coupling reactions are reviewed. Electrophilic aromatic substitution was one of the earliest studied reactions, and the famous Friedel-Crafts reactions have been broadly studied and applied in organic synthesis, though they are not always mentioned while categorized as transition-metal-free coupling reactions. Similarly, nucleophilic aromatic substitution also represents typical transition-metal-free coupling reactions used for electron-deficient aromatic substrates. In radical pathway, base-promoted HAS reactions are a new kind of efficient intermolecular and intramolecular coupling reactions of aryl halides with aromatic compounds and unveil a new method to generate aryl radicals from aryl halides promoted by base-ligand complexes. Hyperiodine(III)-reagent-mediated oxidative couplings for C-C and C-N bond formation reactions are rather simple and clear alternatives to transition-metalcatalyzed editions, especially in the construction of nitrogen-containing heterocycles. In transition-metal-free coupling reactions, photoinduced conditions are usually greatly beneficial for electron transfer to generate active species, such as aryl radicals or aryl cations. Aryne chemistry is also introduced in transition-metal-free couplings of aryl halides for carbon-carbon and carbon-heteroatom bond formation. In transition-metal-catalyzed coupling reactions, the reactions can be modified by tuning many parameters, such as oxidative states of the center metals, ligands coordinated, counteranions.

Zhang X.-S.,CAS Beijing National Laboratory for Molecular | Chen K.,CAS Beijing National Laboratory for Molecular | Shi Z.-J.,CAS Beijing National Laboratory for Molecular | Shi Z.-J.,Chinese Academy of Sciences | Shi Z.-J.,Nankai University
Chemical Science | Year: 2014

Transition metal-catalyzed direct C-H functionalization has drawn great attention in the past several decades owing to its advantages compared to conventional organic transformations, including higher atom-, step- and cost-economy and the avoidance of tedious prefunctionalization and waste emission. At the current stage, to make the C-H functionalization more applicable, chemists have devoted themselves to expanding the substrate and reaction scope. In the past decade, we exerted ourselves to develop new transformations based on direct C-H functionalization. In this minireview we report on our recent achievements on the addition of C-H bonds to carbonyls and imines. The addition of organometallic reagents, such as Grignard reagents, toward carbon-heteroatom double bonds is one of the most powerful reactions in organic synthesis to produce secondary and tertiary alcohols and amines. This chemistry is broadly used in both laboratory and industry. However, this powerful transformation suffers from some drawbacks: (1) the preparation of initial organohalides from easily available fossil feedstocks is tedious and sluggish; (2) substantial amounts of metal halide salts are emitted as waste; (3) last but not least, the manipulation of organometallic reagents is complicated due to their sensitivity to air and moisture. In contrast, direct insertion of polar double bonds to C-H bonds via transition-metal catalysis is ideal from the viewpoint of atom-, step- and cost-economy and the avoidance of the waste emission, as well as of the complex manipulation of sensitive reagents. Starting from this point, we made a commitment to this project years ago and have made credible achievements in this field. We first carried out Ir-catalyzed addition of pyridinyl C-H bonds to aldehydes promoted by silane, showing an unusual C-3 selectivity. Later on, we developed Rh-catalyzed addition of aryl C-H bonds with aldimines in the absence of any additives with directing strategy with highest atom- and step-economy. The mechanism was investigated in depth by the isolation of key intermediates and systematic thermodynamic and kinetic studies. Such a concept was expanded to the coupling of aryl/alkenyl C-H bonds with aldehydes and imines. Notably, a tandem process of relayed C-H activation/alkyne insertion/cyclization between benzoates/benzimide and alkynes was developed, indicating the potential of the direct coupling of esters and amides with C-H bonds. Ideally, this strategy opens a new window to approach the ideal reactions to produce amines and alcohols from hydrocarbons. This journal is © the Partner Organisations 2014.

Pan G.,Soochow University of China | Guo Q.,Soochow University of China | Ma Y.,Nankai University | Yang H.,Soochow University of China | Li B.,Soochow University of China
Angewandte Chemie - International Edition | Year: 2013

The efficient promotion of cell adhesion on a polymer surface and detachment of sheets of cells is possible with thermo-responsive cell culture substrates that are biofunctionalized through noncovalent molecular imprinting. The key is the thermo-responsive "specific binding" of the cell-adhesive peptide RGDS on the cell sheet harvest system (see picture). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang F.,Nankai University | Zhu D.,Nanjing University | Chen W.,Nankai University
Environmental Toxicology and Chemistry | Year: 2012

Understanding the adsorptive interactions between organic contaminants and carbon nanotubes (CNTs) is critical to both environmental applications and risk management of CNTs. The objective of the present study was to understand how transitional metal ions with strong complexing capabilities might affect the adsorption of hydroxyl- and amino-substituted aromatics to surface O-functionality-rich single-walled CNTs (O-SWNT) and N-functionality-rich single-walled CNTs (N-SWNT). Adsorption of 2,4-dichlorophenol, pentachlorophenol, and 1-naphthylamine to O-SWNT and N-SWNT can be significantly enhanced in the presence of Cu(II) (50mg/L), whereas adsorption of 1,2-dichlorobenzene is essentially unaffected. The most likely mechanism for the Cu-enhanced adsorption is that Cu(II) serves as a bridging agent between organic solutes and the functional groups on CNT surfaces. For the adsorption of 1-naphthylamine to N-SWNT, an additional mechanism might be possible; that is, the complexation of Cu(II) with the N-functional groups of N-SWNT can change these groups from strong Lewis bases to Lewis acids and thereby significantly enhance adsorption via the mechanism of Lewis acid-base interactions. In addition, adsorption of Cu(II) can be significantly enhanced by the adsorption of organic cosolutes. © 2011 SETAC.

Li B.,CAS Beijing National Laboratory for Molecular | Wu Z.-H.,CAS Beijing National Laboratory for Molecular | Gu Y.-F.,CAS Beijing National Laboratory for Molecular | Sun C.-L.,CAS Beijing National Laboratory for Molecular | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2011

Go go Grignard! The first highly regioselective, cobalt-catalyzed C-H transformation of benzo[h]quinoline and phenylpyridine derivatives with Grignard reagents at room temperature has been achieved (see scheme). Both aryl and alkyl Grignard reagents showed significant reactivity. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Boutte Y.,Umeå University | Boutte Y.,Swedish University of Agricultural Sciences | Men S.,Umeå University | Men S.,Nankai University | Grebe M.,Umeå University
Nature Protocols | Year: 2011

Sterols are eukaryotic membrane components with crucial roles in diverse cellular processes. Elucidation of sterol function relies on development of tools for in situ sterol visualization. Here we describe protocols for in situ sterol localization in Arabidopsis thaliana root cells, using filipin as a specific probe for detection of fluorescent filipin-sterol complexes. Currently, filipin is the only established tool for sterol visualization in plants. Filipin labeling can be performed on aldehyde-fixed samples, largely preserving fluorescent proteins and being compatible with immunocytochemistry. Filipin can also be applied for probing live cells, taking into account the fact that it inhibits sterol-dependent endocytosis. The experimental procedures described are designed for fluorescence detection by confocal laser-scanning microscopy with excitation of filipin-sterol complexes at 364 nm. The protocols require 1 d for sterol covisualization with fluorescent proteins in fixed or live roots and 2 d for immunocytochemistry on whole-mount roots. © 2011 Nature America, Inc. All rights reserved.

Zhang S.,University of Houston | Zhang S.,Nankai University | Mercado-Uribe I.,University of Houston | Xing Z.,University of Houston | And 3 more authors.
Oncogene | Year: 2014

Polyploid giant cancer cells (PGCCs) have been observed by pathologists for over a century. PGCCs contribute to solid tumor heterogeneity, but their functions are largely undefined. Little attention has been given to these cells, largely because PGCCs have been generally thought to originate from repeated failure of mitosis/cytokinesis and have no capacity for long-term survival or proliferation. Here we report our successful purification and culture of PGCCs from human ovarian cancer cell lines and primary ovarian cancer. These cells are highly resistant to oxygen deprivation and could form through endoreduplication or cell fusion, generating regular-sized cancer cells quickly through budding or bursting similar to simple organisms like fungi. They express normal and cancer stem cell markers, they divide asymmetrically and they cycle slowly. They can differentiate into adipose, cartilage and bone. A single PGCC formed cancer spheroids in vitro and generated tumors in immunodeficient mice. These PGCC-derived tumors gained a mesenchymal phenotype with increased expression of cancer stem cell markers CD44 and CD133 and become more resistant to treatment with cisplatin. Taken together, our results reveal that PGCCs represent a resistant form of human cancer using an ancient, evolutionarily conserved mechanism in response to hypoxia stress; they can contribute to the generation of cancer stem-like cells, and also play a fundamental role in regulating tumor heterogeneity, tumor growth and chemoresistance in human cancer. © 2014 Macmillan Publishers Limited.

Xie J.,Nanjing University | Huang Z.-Z.,Nanjing University | Huang Z.-Z.,Nankai University
Angewandte Chemie - International Edition | Year: 2010

The direct approach: The title coupling reactions of N-aryl glycine esters with unmodified ketones occurred smoothly in the presence of tert-butyl hydroperoxide (TBHP) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) under mild conditions (see scheme). The oxidant used for C-H activation determined the selectivity of the reactions for a particular type of ketone substrate. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang Y.,CAS Beijing National Laboratory for Molecular | Chi Y.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,Nankai University | Xi Z.,CAS Beijing National Laboratory for Molecular
Journal of the American Chemical Society | Year: 2012

A highly regioselective base-mediated ring expansion of 2,4-diiminoazetidines via cleavage of C-N and C(sp 3)-H bonds is achieved for the first time to afford efficiently 2,3- dihydropyrimidinesulfonamides. The mechanism of the ring expansion via tandem 4π electrocyclic ring-opening/1,5-H shift/6π electrocyclic ring-closing is well confirmed by the trapping experiments of two key intermediates and deuterium labeling studies. © 2012 American Chemical Society.

Li W.,Nankai University | Nanaboina V.,University of Washington | Zhou Q.,Nankai University | Korshin G.V.,University of Washington
Water Research | Year: 2012

This study examined effects of Fenton oxidation on trace level pharmaceuticals and personal care products (PPCPs) commonly occurring in wastewater. The tested PPCPs included acetaminophen, atenolol, atrazine, carbamazepine, metoprolol, dilantin, DEET, diclofenac, pentoxifylline, oxybenzone, caffeine, fluoxetine, gemfibrozil, ibuprofen, iopromide, naproxen, propranolol, sulfamethoxazole, bisphenol-A and trimethoprim. Transformations of effluent organic matter (EfOM) caused by Fenton oxidation were also quantified. All tested PPCPs, except atrazine and iopromide, were completely removed by Fenton treatment carried out using a 20mg/L Fe (II) concentration and a 2.5 H 2O 2/Fe (II) molar ratio. Up to 30% on the total carbon concentration was removed during Fenton treatment which was accompanied by the oxidation of EfOM molecules and formation of oxidation products such as oxalic, formic and acetic acids and, less prominently, formaldehyde, acetaldehyde, propionaldehyde and glycolaldehyde. The absorbance of EfOM treated with Fenton reagent at varying Fe (II) concentration and contact time underwent a consistent decrease. The relative decrease of EfOM absorbance was strongly and unambiguously correlated with the removal of all tested PPCPs. © 2011 Elsevier Ltd.

Wang Y.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,Nankai University | Wang Z.,CAS Beijing National Laboratory for Molecular | Xi Z.,CAS Beijing National Laboratory for Molecular
Angewandte Chemie - International Edition | Year: 2011

Concise and selective: The procedure-controlled synthesis of the title compounds has been achieved for the first time by an organolithium-promoted convergent tandem annulation involving readily available terminal alkynes, chalcogen elements (S, Se, and Te), carbodiimides, and acid chlorides. A novel 1,5-acyl migration is considered to be essential for this useful transformation. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hong P.,Nanjing University of Science and Technology | Zhang G.,Nankai University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

Recently, we have demonstrated that second-order subwavelength interference could be realized in an optical lithography scheme with an effective entangled source [P. Hong and G. Zhang, Phys. Rev. A 88, 043838 (2013)PLRAAN1050-294710.1103/PhysRevA.88.043838]. In this paper, by considering the correlation function in both the source plane and observation plane, we show how the coherence property of such a source is controlled via introduction of random-phase correlation, which finally affects the two-photon interference effect observed in the far-field plane. Furthermore, by introducing different but similar random-phase correlations, we generalize the phase controlled source with particular high-order coherence properties to obtain higher-order subwavelength interference, i.e., high-order super-resolved optical lithography. These results show the importance of phase control in generating a light field with particular high-order coherence properties. ©2015 American Physical Society.

Liu M.,Nankai University | La Croix S.,University of Hawaii at Manoa
Research Policy | Year: 2015

Building on the seminal work of Ginarte and Park (1997. Research Policy. 26, 283-301), we develop an index of property rights in pharmaceutical inventions, the Pharmaceutical Intellectual Property Protection (PIPP) Index, for 154 countries spanning 1960 to 2005. It incorporates five types of property rights in pharmaceuticals; six statutory measures of enforcement; and adherence to three international agreements providing for the grant and enforcement of rights to foreigners. For both developed and developed countries, the PIPP Index starts at low levels in 1960, increases slowly through the early 1990s, and then sharply increases due to minimum standards set by the 1995 TRIPS Agreement. © 2014 Elsevier B.V. All rights reserved.

Zhang J.,Zhengzhou University | Wang K.,Zhengzhou University | Xu Q.,Zhengzhou University | Zhou Y.,CAS Changchun Institute of Applied Chemistry | And 2 more authors.
ACS Nano | Year: 2015

To well address the problems of large volume change and dissolution of Fe3O4 nanomaterials during Li+ intercalation/extraction, herein we demonstrate a one-step in situ nanospace-confined pyrolysis strategy for robust yolk-shell nanospindles with very sufficient internal void space (VSIVS) for high-rate and long-term lithium ion batteries (LIBs), in which an Fe3O4@Fe3C core@shell nanoparticle is well confined in the compartment of a hollow carbon nanospindle. This particular structure can not only introduce VSIVS to accommodate volume change of Fe3O4 but also afford a dual shell of Fe3C and carbon to restrict Fe3O4 dissolution, thus providing dual roles for greatly improving the capacity retention. As a consequence, Fe3O4@Fe3C-C yolk-shell nanospindles deliver a high reversible capacity of 1128.3 mAh g-1 at even 500 mA g-1, excellent high rate capacity (604.8 mAh g-1 at 2000 mA g-1), and prolonged cycling life (maintaining 1120.2 mAh g-1 at 500 mA g-1 for 100 cycles) for LIBs, which are much better than those of Fe3O4@C core@shell nanospindles and Fe3O4 nanoparticles. The present Fe3O4@Fe3C-C yolk-shell nanospindles are the most efficient Fe3O4-based anode materials ever reported for LIBs. © 2015 American Chemical Society.

Li X.,CAS Beijing National Laboratory for Molecular | Luo S.,CAS Beijing National Laboratory for Molecular | Cheng J.-P.,Nankai University
Chemistry - A European Journal | Year: 2010

Chiral pyrroloindoles: A highly enantioselective catalytic conjugate addition of 3-substituted oxindoles with 2-chloroacrylonitrile has been developed with a readily accessible alkyl bifunctional tertiary amine thiourea catalyst. Excellent stereoselectivity of up to >30:1 diastereomeric ratio and 99% enantiomeric excess was achieved. The obtained Michael products could be easily converted to chiral pyrroloindole structures, which are widely distributed in natural indole alkaloids (see scheme). Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luo S.,CAS Beijing National Laboratory for Molecular | Zhou P.,Nankai University | Li J.,CAS Beijing National Laboratory for Molecular | Cheng J.-P.,Nankai University
Chemistry - A European Journal | Year: 2010

(Chemical Figure Presented) One stone four birds: A single chiral primary amine was found to catalyze unprecedented asymmetric retro-aldol and transfer-aldol reactions, leading to four different chiral aldol adducts from one common chiral source with up to 99:1 d.r. and 99% ee (see scheme). © 2010 Wiley-VCH Verlag GmbH& Co. KGaA.

Gu Z.-Y.,Nankai University | Wang G.,Tianjin Academy of Environmental science | Yan X.-P.,Nankai University
Analytical Chemistry | Year: 2010

Metal-organic frameworks (MOFs) are one kind of highly porous crystalline materials, which are constructed by metal-containing inorganic nodes and organic linkers. With large surface area and high thermal stability, MOFs have great potential as sorbents for the preconcentration of trace analytes. However, such application of MOFs to the analysis of real samples has not been reported before. Here we report the utilization of MOF-5 as sorbent for in-field sampling and preconcentration of atmospheric formaldehyde before thermal desorption (TD) GC/MS (TD-GC/ MS) determination without the need for any chemical derivatization. MOF-5 gave a 53 and 73 times better concentration effect than Tenax TA (organic polymers) and Carbograph 1TD (graphitized carbon black), respectively, for TD-GC/MS determination of formaldehyde. MOF-5 showed good performance for in-field sampling and preconcentration of formaldehyde from air samples with a relative humidity less than 45%. The collected formaldehyde on MOF-5 sorbent was stable for at least 72 h at room temperature before TD-GC/MS analysis. One tube packed with 300 mg of MOF-5 lasted 200 cycles of adsorption/TD without significant loss of collection ef-ficiency. The breakthrough volume of such a tube was 1.2 L of 28.35 mg m-3 formaldehyde at a sampling flow rate of 100 mL min-1. The use of MOF-5 for in-field sampling and preconcentration in combination with TD-GC/MS for the determination of formaldehyde offered a linear range covering 3 orders of magnitude, and a detection limit of 0.6 μ g m-3. The precision for six replicate cycles of in-field sampling and preconcentration for TD-GC/MS determination using one 300 mg MOF-5 packed tube ranged from 2.8% to 5.3%. The tube-to-tube reproducibility of three MOF-5 tubes prepared in parallel was 7.7%. The developed method was applied to analysis of local indoor and outdoor air samples for formaldehyde and validated by the standard method TO-11A of the United States Environmental Protection Agency. The concentration of formaldehyde and the recovery of spiked formaldehyde in the air samples ranged from 12 to 48 μ gm-3, and from 93% to 107%, respectively. © 2010 American Chemical Society.

Guang X.,Nankai University | Fu F.-W.,Nankai University | Zhang Z.,University of Southern California
IEEE Transactions on Information Theory | Year: 2013

Recently, network error correction coding (NEC) has been studied extensively. Several bounds in classical coding theory have been extended to NEC, especially the Singleton bound. In this paper, following the research line using the extended global encoding kernels proposed by Zhang in 2008, the refined Singleton bound of NEC can be proved more explicitly. Moreover, we give a constructive proof of the attainability of this bound and indicate that the required field size for the existence of network maximum distance separable (MDS) codes can become smaller further. By this proof, an algorithm is proposed to construct general linear network error correction codes including the linear network error correction MDS codes. Finally, we study the error correction capability of random linear NEC. Motivated partly by the performance analysis of random linear network coding, we evaluate the different failure probabilities defined in this paper in order to analyze the performance of random linear NEC. Several upper bounds on these probabilities are obtained and they show that these probabilities will approach to zero as the size of the base field goes to infinity. Using these upper bounds, we slightly improve on the probability mass function of the minimum distance of random linear network error correction codes in a paper by Balli and colleagues, as well as the upper bound on the field size required for the existence of linear network error correction codes with degradation at most d. © 1963-2012 IEEE.

Li Y.,East China Normal University | Pu J.,East China Normal University | Jiang X.,East China Normal University | Jiang X.,CAS Beijing National Laboratory for Molecular | Jiang X.,Nankai University
Organic Letters | Year: 2014

A highly efficient Cu-catalyzed dual C-S bonds formation reaction, proceeding in alcohol and water under air, is reported, in which inodorous stable Na2S2O3 is used as a sulfurating reagent. This powerful strategy provides a practical and efficient approach to construct thioethers, using readily available aromatic amines and alkyl halides as starting materials. Sensitive and synthetic useful functional groups could be tolerated. Furthermore, pharmaceuticals, glucose, an amino acid, and a chiral ligand are successfully furnished by this late-stage sulfuration strategy. © 2014 American Chemical Society.

Zhang W.-X.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,Nankai University | Xu L.,CAS Beijing National Laboratory for Molecular | Xi Z.,CAS Beijing National Laboratory for Molecular
Chemical Communications | Year: 2015

Multisubstituted guanidines have received much attention because of important applications in many fields, such as pharmaceutics, organometallic and coordination chemistry, and organic synthesis. Although classical methods are available for the preparation of guanidines, synthetic preparation approaches to guanidines are still in great demand. In this review, we summarize recent developments on synthetic methods via the C-N bond formation. Three aspects are included: transition-metal-catalyzed guanidine synthesis based on classical methods; catalytic guanylation reaction of amines with carbodiimides; and tandem catalytic guanylation/cyclization reactions. This journal is © The Royal Society of Chemistry 2015.

Ouyang K.,CAS Beijing National Laboratory for Molecular | Ouyang K.,CAS Institute of Chemistry | Hao W.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,CAS Beijing National Laboratory for Molecular | And 2 more authors.
Chemical Reviews | Year: 2015

Transition-metal-catalyzed cleavage of C-N single bonds has become a hot area, because it provides either an excellent nitrogen source or an excellent carbon source from readily available and simple N-containing compounds to construct useful molecules. With detailed mechanistic studies on the cleavage of various C-N bonds, scientists have gained some insight into the nature of this process and developed many important concepts in the field of inert chemical bond activation. Generally, one molecule of a N-containing compound acts as either a carbon source or a nitrogen source in one reaction via C-N bond cleavage. The whole atom economy is low. Therefore, improvement of the atom economy of the C-N bond cleavage process will become a promising area. If only the C-containing fragment as the carbon source is incorporated into the target molecules, the C-N bond cleavage in primary amines is more atom-economical than that in other amines because only a mass of 17 amu in primary amines will be missing.

Yang F.,Nanjing University | Li J.,Nanjing University | Xie J.,Nanjing University | Huang Z.-Z.,Nanjing University | Huang Z.-Z.,Nankai University
Organic Letters | Year: 2010

A novel cross dehydrogenative coupling (CDC) reaction of N,N-dimethylanilines with methyl ketones by cooperative copper and aminocatalysis has been developed, which leads to the formation of β-arylamino ketones in 42-73% yields. Moreover, the copper-catalyzed alkylation of free (NH) indoles with N,N-dimethylanilines via CDC reaction is also presented, affording alkylated indoles in 52-78% yields. © 2010 American Chemical Society.

Chi Y.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,CAS Beijing National Laboratory for Molecular | Zhang W.-X.,Nankai University | Xi Z.,CAS Beijing National Laboratory for Molecular
Organic Letters | Year: 2014

The iodine(III) compound promoted C-H amination and tandem C-H amination/acetoxylation of guanidines are achieved for the first time to provide efficiently 2-aminobenzimidazoles and acetoxyl-substituted 2-aminobenzimidazoles, respectively. The amount and type of iodine(III) compounds control the selective syntheses of two types of 2-aminobenzimidazoles. This reaction shows good regioselectivity when unsymmetrical substrates are used. © 2014 American Chemical Society.

Wang Z.,Nankai University | Zhang N.,Nanyang Technological University | Yuan X.-C.,Nankai University
Optics Express | Year: 2011

We report an approach to the increase of signal channels in free-space optical communication based on composed optical vortices (OVs). In the encoding process, conventional algorithm employed for the generation of collinearly superimposed OVs is combined with a genetic algorithm to achieve high-volume OV multiplexing. At the receiver end, a novel Dammann vortex grating is used to analyze the multihelix beams with a large number of OVs. We experimentally demonstrate a digitized system which is capable of transmitting and receiving 16 OV channels simultaneously. This system is expected to be compatible with a high-speed OV multiplexing technique, with potentials to extremely high-volume information density in OV communication. © 2011 Optical Society of America.

Yuan G.,Nanyang Technological University | Wang Q.,Nanyang Technological University | Yuan X.,Nankai University
Optics Letters | Year: 2012

Dynamic generation of plasmonic Moiré fringes using a phase engineered optical vortex (OV) beam is experimentally demonstrated. Owing to the unique helical phase carried by an OV beam, the initial phase of surface plasmon polaritons (SPPs) emanating from a metallic grating can be adjusted dynamically by changing the phase hologram displayed on a spatial light modulator. Plasmonic Moiré fringes are readily achieved by overlapping two SPP standing waves with certain angular misalignment, excited by the positive and negative topological charge components, respectively, of a cogwheel-like OV beam. The near-field scanning optical microscopy measurement result of SPP distributions has shown a good agreement with the numerical predictions. © 2012 Optical Society of America.

Cao Y.,Hong Kong Polytechnic University | Jin W.,Hong Kong Polytechnic University | Ho L.H.,Hong Kong Polytechnic University | Liu Z.,Hong Kong Polytechnic University | Liu Z.,Nankai University
Optics Letters | Year: 2012

We demonstrate gas detection based on evanescent-wave photoacoustic (PA) spectroscopy with tapered optical fibers. Evanescent-field instead of open-path absorption is exploited for PA generation, and a quartz tuning fork is used for PA detection. A tapered optical fiber with a diameter down to the wavelength scale demonstrates detection sensitivity similar to an open-path system but with the advantages of easier optical alignment, smaller insertion loss, and multiplexing capability. © 2012 Optical Society of America.

Feng D.,Guangdong Medical College | Liu L.,CAS Institute of Zoology | Zhu Y.,Nankai University | Chen Q.,CAS Institute of Zoology | Chen Q.,Nankai University
Experimental Cell Research | Year: 2013

Mitochondrial autophagy or mitophagy is a cellular metabolic pathway that mediates the selective elimination of dysfunctional or unwanted mitochondria. Considerable advancements have been made to elucidate the molecular mechanism behind mitophagy, particularly Parkin-mediated mitophagy. Several mitophagy receptors have been discovered in different physiological settings, including ATG32 in yeast as well as NIX, BNIP3, and FUNDC1 in mammalian cells. However, the signaling events that regulate these mitophagy receptors and their physiological significance in human diseases are poorly understood. In this paper, we review recent advancements in mitophagy at the cellular and molecular levels. © 2013 Elsevier Inc.

Dong C.,Nankai University | Yang X.,Nankai University | Hou H.-F.,CAS Institute of High Energy Physics | Shen Y.-Q.,Nankai University | Dong Y.-H.,CAS Institute of High Energy Physics
Acta Crystallographica Section D: Biological Crystallography | Year: 2012

In Escherichia coli, the BAM complex is essential for the assembly and insertion of outer membrane proteins (OMPs). The BAM complex is comprised of an integral Β-barrel outer membrane protein BamA and four accessory lipoproteins BamB, BamC, BamD and BamE. Here, the crystal structure of BamB is reported. The crystal of BamB diffracted to 2.0 Å with one monomer in the asymmetric unit and the structure is composed of eight-bladed Β-propeller motifs. Pull-down and Western blotting assays indicate that BamB interacts directly with the POTRA 1-3 domain of BamA and the C - terminal region of the POTRA 1-3 domain plays an important role in the interaction, while the POTRA 1-2 domain is not required for the interaction. © 2012 International Union of Crystallography Printed in Singapore - all rights reserved.

Dong C.,CAS Institute of High Energy Physics | Dong C.,Nankai University | Hou H.-F.,CAS Institute of High Energy Physics | Yang X.,Nankai University | And 2 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2012

The outer membrane protein complex (BAM complex) plays an important role in outer membrane protein (OMP) assembly in Escherichia coli. The BAM complex includes the integral β-barrel protein BamA as well as four lipoproteins: BamB, BamC, BamD and BamE. One of these lipoproteins, BamD, is essential for the survival of Escherichia coli. The structure of BamD at 2.6 Å resolution shows that this lipoprotein is composed of ten α-helices that form five tetratricopeptide-repeat (TPR) motifs. The arrangement of the BamD motifs is similar to that in the periplasmic part of BamA. One of the ten α-helices, α10, which has been shown to be important for the assembly of the BAM complex, is located in the very C-terminal region of BamD. A deep groove between TPR domains 4 and 5 is also observed. This groove, as well as the surface around α10, may provide binding sites for other components of the BAM complex. The C-terminal region of BamD serves as a platform for interactions with other components of the BAM complex. The N-terminal region shares structural similarity to other proteins whose functions are related to assistance in or regulation of secretion. Therefore, this region is likely to play an important role in the insertion of other outer membrane proteins. © 2012 International Union of Crystallography.

Zhang D.G.,Nanyang Technological University | Moh K.J.,Nanyang Technological University | Yuan X.-C.,Nankai University
Optics Express | Year: 2010

Surface plasmon-coupled emission from shaped PMMA films doped with randomly oriented fluorescence molecules was investigated. Experimental results show that for different shapes, such as triangle or circular structures, the SPCE ring displays different intensity patterns. For a given shape, it was observed that the relative position and polarization of an incident laser spot on the shaped PMMA can be used to adjust the fluorescence intensity distribution of the SPCE ring. The proposed method enables controlling the fluorescence emission in azimuthal direction in addition to the radial angle controlled by common SPCE, which will further enhances the fluorescence collection efficiency and has applications in fluorescence sensing, imaging and so on. © 2010 Optical Society of America.

Liu J.,Northeast Normal University | Fang Z.,Northeast Normal University | Zhang Q.,Northeast Normal University | Liu Q.,Northeast Normal University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2013

Ag2CO3 is the key: The transition-metal-catalyzed cycloaddition of isocyanides and unactivated terminal alkynes has been realized with Ag2CO3 as a unique and robust catalyst (see scheme). The protocol is highly efficient, allowing a broad range of terminal and internal alkynes to react under base- and ligand-free conditions, generating synthetically useful oligosubstituted pyrroles in high yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yuan G.H.,Nanyang Technological University | Wei S.B.,Nankai University | Yuan X.-C.,Nankai University
Optics Letters | Year: 2011

Generation of a nondiffracting transversally polarized beam by means of transmitting an azimuthally polarized beam through a multibelt spiral phase hologram and then highly focusing by a high-NA lens is presented. A relatively long depth of focus (∼4:84 λ) of the electric field with only radial and azimuthal components is achieved. The polarization of the wavefront near the focal plane is analyzed in detail by calculating the Stokes polarization parameters. It is found that the polarization is spatially varying and entirely transversally polarized, and the polarization singularity disappears at the beam center, which makes the central bright channel possible. © 2011 Optical Society of America.

Zhang L.,Northeast Normal University | Bi X.,Northeast Normal University | Bi X.,Nankai University | Guan X.,Northeast Normal University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2013

Aldehyde Termination: A novel copper-catalyzed transformation from methyl ketones into aldehydes has been accomplished. This method is applicable to a wide range of aromatic and aliphatic methyl ketones and chemoselectively produces aldehydes, accompanied by the release of hydrogen (H2) and carbon dioxide (CO2) as by-products. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang Q.,Nanyang Technological University | Bu J.,Nankai University | Yuan X.-C.,Nankai University
Optics Express | Year: 2010

The authors demonstrate a two dimensional (2D) plasmonic fan-out spot array by using subwavelength sized slit arrays. Near field scanning optical microscope (NSOM) is employed to examine intensity distributions of the generated fan-out plasmonic spots, showing good agreement with finite-difference time-domain (FDTD) simulation results. The plasmonic fan-out spots with full width half-maximum (FWHM) of 0.34λ0 are optimized by various design parameters associated with the subwavelength slit as well as polarization states. © 2010 Optical Society of America.

Li Y.-W.,Nankai University | Li J.-R.,Beijing University of Technology | Wang L.-F.,Nankai University | Zhou B.-Y.,Nankai University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Two cluster-based microporous MOFs containing coordination unsaturated metal(ii) sites (or open metal(ii) sites) have been constructed from boxlike or cagelike {M3}x SBUs. They both exhibit highly selective uptake for CO2 over CH4 and N2 under ambient conditions. More importantly, MOF-1 also provides an ideal luminescence sensor for selective probing Ba2+ and Cu2+ ions based on significant luminescence enhancement or quenching. This journal is © 2013 The Royal Society of Chemistry.

Zhang N.,Nanyang Technological University | Yuan X.C.,Nankai University | Burge R.E.,University of Cambridge
Optics Letters | Year: 2010

We report a 2D static binary phase Dammann vortex grating that combines the features of a conventional vortex grating and a Dammann grating. This grating uniformly distributes energies among the diffraction orders, so the low- efficiency problem at higher diffraction orders of conventional vortex gratings is resolved and the detection range of the optical vortices [OVs] is greatly increased. Experimental results of OV detection using a fabricated 5 × 5 Dammann vortex grating are given, and the topological charge detection range from -12 to +12 is achieved. The potential applications of such gratings include transmitting, receiving, and multiplexing OV beams in optical communication systems. © 2010 Optical Society of America.

Liu J.,Northeast Normal University | Liu Z.,Northeast Normal University | Wu N.,Northeast Normal University | Liao P.,Northeast Normal University | And 2 more authors.
Chemistry - A European Journal | Year: 2014

Cross-coupling reactions between propargylic alcohols and isocyanides, by means of silver catalysis, have been described. This new reaction is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2,3-allenamides in moderate to excellent yields. Making allenamides: Cross-coupling reactions between propargylic alcohols and isocyanides, by means of silver catalysis, are described. This new reaction is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2,3-allenamides in moderate to excellent yields (see scheme). Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chu J.,CAS Shanghai Institute of Organic Chemistry | Lu E.,CAS Shanghai Institute of Organic Chemistry | Liu Z.,CAS Shanghai Institute of Organic Chemistry | Chen Y.,CAS Shanghai Institute of Organic Chemistry | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

A complex complex: The reactions of a scandium terminal imido complex with a series of unsaturated substrates, including CO2, PhCN, methyl methacrylate (MMA), cyclopentadiene, PhNCO, and propylene oxide, are presented (see scheme). A variety of intriguing products are formed from this complex. Ar=2,6-(iPr)2C6H3. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu Z.-B.,Hong Kong Polytechnic University | Liu Z.-B.,Nankai University | He X.,Hong Kong Polytechnic University | Wang D.N.,Hong Kong Polytechnic University
Optics Letters | Year: 2011

We demonstrate a nanosecond-pulse erbium-doped fiber laser that is passively mode locked by a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution. Owing to the good solution processing capability of few-layered graphene oxide, which can be filled into the core of a hollow-core photonic crystal fiber through a selective hole filling process, a graphene saturable absorber can be successfully fabricated. The output pulses obtained have a center wavelength, pulse width, and repetition rate of 1561:2nm, 4:85 ns, and 7:68MHz, respectively. This method provides a simple and efficient approach to integrate the graphene into the optical fiber system. © 2011 Optical Society of America.

Fang Z.,Northeast Normal University | Liu J.,Northeast Normal University | Liu Q.,Northeast Normal University | Bi X.,Northeast Normal University | Bi X.,Nankai University
Angewandte Chemie - International Edition | Year: 2014

Cyclopentadienes are valuable intermediates in organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that employ functionalized alkynes, a [3+2] cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5-dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels-Alder reaction, the cyclopentadienes were further reacted with maleimides to afford a family of novel fluorescent polycyclic compounds. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu Z.,Northeast Normal University | Liu J.,Northeast Normal University | Zhang L.,Northeast Normal University | Liao P.,Northeast Normal University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

The hydroazidation of alkynes is the most straightforward pathway to synthetically useful vinyl azides. However, a general hydroazidation of alkynes remains elusive. Herein, a chemo- and regioselective transformation of ethynyl carbinols into vinyl azides is described. This reaction produces a wide variety of 2-azidoallyl alcohols with high efficiency and in good to excellent yields. These compounds constitute a new class of densely functionalized synthetic intermediates. Their synthetic potential has been demonstrated by further transformations into NH aziridines. The mechanistic aspects of the reaction will attract the attention of chemists working on alkyne chemistry and silver catalysis. The findings that are described in this paper represent significant advances in the regioselective hydroelementation of alkynes and open a new reaction manifold for exploitation. Azides and aziridines: The hydroazidation of unactivated alkynes by means of silver catalysis is described. A variety of ethynyl carbinols are capable of reacting with trimethylsilyl azide to produce 2-azidoallyl alcohols in good to excellent yields. The synthetic utility of 2-azidoallyl alcohols was demonstrated by further conversion into NH aziridines. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu B.,Nankai University | Zhou T.,Nankai University | Li B.,Nankai University | Xu S.,Nankai University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

The alkenylation reactions of 8-methylquinolines with alkynes, catalyzed by [{Cp*RhCl2}2], proceeds efficiently to give 8-allylquinolines in good yields by C(sp3)-H bond activation. These reactions are highly regio- and stereoselective. A catalytically competent five-membered rhodacycle has been structurally characterized, thus revealing a key intermediate in the catalytic cycle. Highly regio- and stereoselective alkenylation reactions of 8-methylquinolines with alkynes give 8-allylquinolines in good yields. These reactions are catalyzed by [{Cp*RhCl 2}2] (Cp*=C5Me5) and proceed by C(sp3)-H bond activation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dai W.,Central University of Costa Rica | Chen X.,Nankai University
Mathematical and Computer Modelling | Year: 2012

Uncertainty theory is a branch of mathematics of studying the subjective uncertain behavior. Entropy is a key concept which provides a quantitative measurement of the uncertainty associated with uncertain variables. In order to compute the entropy more conveniently, this paper proposes some formulas of entropy of function of uncertain variables with regular uncertain distributions. Furthermore, the positive linearity property of the entropy operator is proved immediately following from these formulas at last. © 2011.

Fang Z.,Northeast Normal University | Ning Y.,Northeast Normal University | Mi P.,Northeast Normal University | Liao P.,Northeast Normal University | And 2 more authors.
Organic Letters | Year: 2014

A copper(I)-catalyzed, regioselective C-H α-trifluoromethylation of α,β-unsaturated carbonyl compounds using Togni's reagent was developed. Diverse substrates, including enones as well as α,β- unsaturated esters, thioesters, and amides, stereospecifically afforded the corresponding (E)-α-trifluoromethylated products in moderate to high yields. Further, this method was applied to the C-H trifluoromethylation of drugs. © 2014 American Chemical Society.

Tan X.,Nankai University | Liu B.,Nankai University | Li X.,Nankai University | Li B.,Nankai University | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp 2)-H/C(sp 3)-H and C(sp 2)-H/O-H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp 2)-H/C(sp 3)-H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C(sp 2)-H/O-H bonds, affording the 1:2 coupling products. Moreover, some of the naphtho[1,8-bc]pyran products exhibit intense fluorescence in the solid state. © 2012 American Chemical Society.

Fang G.,Northeast Normal University | Bi X.,Northeast Normal University | Bi X.,Nankai University
Chemical Society Reviews | Year: 2015

Silver is a less expensive noble metal. Superior alkynophilicity due to π-coordination with the carbon-carbon triple bond makes silver salts ideal catalysts for alkyne-based organic reactions. This review highlights the progress in alkyne chemistry via silver catalysis primarily over the past five years (ca. 2010-2014). The discussion is developed in terms of the bond type formed with the acetylenic carbon (i.e., C-C, C-N, C-O, C-Halo, C-P and C-B). Compared with other coinage metals such as Au and Cu, silver catalysis is frequently observed to be unique. This critical review clearly indicates that silver catalysis provides a significant impetus to the rapid evolution of alkyne-based organic reactions, such as alkynylation, hydrofunctionalization, cycloaddition, cycloisomerization, and cascade reactions. © The Royal Society of Chemistry.

Liu Z.,Northeast Normal University | Liao P.,Northeast Normal University | Bi X.,Northeast Normal University | Bi X.,Nankai University
Organic Letters | Year: 2014

A general hydroazidation of unactivated alkynes using silver catalysis is reported. The reactions of diverse terminal alkynes with trimethylsilyl azide (TMS-N3) in the presence of H2O afforded the corresponding vinyl azides in good to excellent yields. This reaction has a broad substrate scope, good functional group tolerance, simple operation, and high reaction efficiency, thus providing an easy access to various functionalized vinyl azides. © 2014 American Chemical Society.

Tang Q.,University of Puerto Rico at San Juan | Tang Q.,Nankai University | Zhou Z.,Nankai University | Chen Z.,University of Puerto Rico at San Juan
Journal of Physical Chemistry C | Year: 2011

The electronic properties of BN nanosheets and nanoribbons doped with organic molecules with strong electron-donating or accepting abilities were investigated by means of density functional theory computations. The interfacial charge transfer between BN nanosheets and the acceptor (tetracyanoquinodimethane, TCNQ) or donor (tetrathiafulvalene, TTF) molecule significantly reduces the intrinsic wide band gap of pristine BN nanosheets and consequently results in a p- or n-type semiconductor, respectively. Similar behavior is observed for both zigzag and armchair-edged BN nanoribbons. These findings suggest a simple and effective route to tune the electronic properties of BN materials in a wide range and also facilitate the design of BN-based molecular electronics. © 2011 American Chemical Society.