News Article | June 22, 2017
At EPFL, researchers challenge a fundamental law and discover that more electromagnetic energy can be stored in wave-guiding systems than previously thought. The discovery has implications in telecommunications. Working around the fundamental law, they conceived resonant and wave-guiding systems capable of storing energy over a prolonged period while keeping a broad bandwidth. Their trick was to create asymmetric resonant or wave-guiding systems using magnetic fields. The study, which has just been published in Science, was led by Kosmas Tsakmakidis, first at the University of Ottawa and then at EPFL's Bionanophotonic Systems Laboratory run by Hatice Altug, where the researcher is now doing post-doctoral research. This breakthrough could have a major impact on many fields in engineering and physics. The number of potential applications is close to infinite, with telecommunications, optical detection systems and broadband energy harvesting representing just a few examples. Resonant and wave-guiding systems are present in the vast majority of optical and electronic systems. Their role is to temporarily store energy in the form of electromagnetic waves and then release them. For more than 100 hundred years, these systems were held back by a limitation that was considered to be fundamental: the length of time a wave could be stored was inversely proportional to its bandwidth. This relationship was interpreted to mean that it was impossible to store large amounts of data in resonant or wave-guiding systems over a long period of time because increasing the bandwidth meant decreasing the storage time and quality of storage. This law was first formulated by K. S. Johnson in 1914, at Western Electric Company (the forerunner of Bell Telephone Laboratories). He introduced the concept of the Q factor, according to which a resonator can either store energy for a long time or have a broad bandwidth, but not both at the same time. Increasing the storage time meant decreasing the bandwidth, and vice versa. A small bandwidth means a limited range of frequencies (or 'colors') and therefore a limited amount of data. Until now, this concept had never been challenged. Physicists and engineers had always built resonant systems -- like those to produce lasers, make electronic circuits and conduct medical diagnoses -- with this constraint in mind. But that limitation is now a thing of the past. The researchers came up with a hybrid resonant / wave-guiding system made of a magneto-optic material that, when a magnetic field is applied, is able to stop the wave and store it for a prolonged period, thereby accumulating large amounts of energy. Then when the magnetic field is switched off, the trapped pulse is released. With such asymmetric and non-reciprocal systems, it was possible to store a wave for a very long period of time while also maintaining a large bandwidth. The conventional time-bandwidth limit was even beaten by a factor of 1,000. The scientists further showed that, theoretically, there is no upper ceiling to this limit at all in these asymmetric (non-reciprocal) systems. "It was a moment of revelation when we discovered that these new structures did not feature any time-bandwidth restriction at all. These systems are unlike what we have all been accustomed to for decades, and possibly hundreds of years», says Tsakmakidis, the study's lead author. "Their superior wave-storage capacity performance could really be an enabler for a range of exciting applications in diverse contemporary and more traditional fields of research." Hatice Altug adds. One possible application is in the design of extremely quick and efficient all-optical buffers in telecommunication networks. The role of the buffers is to temporarily store data arriving in the form of light through optical fibers. By slowing the mass of data, it is easier to process. Up to now, the storage quality had been limited.+ With this new technique, it should be possible to improve the process and store large bandwidths of data for prolonged times. Other potential applications include on-chip spectroscopy, broadband light harvesting and energy storage, and broadband optical camouflaging ("invisibility cloaking"). "The reported breakthrough is completely fundamental -- we're giving researchers a new tool. And the number of applications is limited only by one's imagination," sums up Tsakmakidis. Source: Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering Kosmas Tsakmakidis, lead author, former researcher at the University of Ottawa and currently an EPFL Fellow in EPFL's Bionanophotonic Systems Laboratory Linfang Shen and collaborators, Institute of Space Science and Technology, Nanchang University, Nanchang, China and State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, China Prof. Robert Boyd and collaborators, University of Ottawa Prof. Hatice Altug, director of EPFL's Bionanophotonic Systems Laboratory Prof. Alexandre Vakakis, University of Illinois at Urbana-Champaign
Deng X.-F.,Nanchang University
Astrophysical Journal | Year: 2010
From theMain galaxy sample of the Sloan Digital Sky Survey Data Release 7, I construct two volume-limited samples with luminosities -20.5 ≤ M r ≤ -18.5 and -22.5≤ Mr ≤-20.5, respectively, to explore the environmental dependence of the star formation rate (SFR) and the specific star formation rate (SSFR) at fixed morphology. It is found that in these two volume-limited samples, galaxies in the lowest density regime preferentially have higher SFR and SSFR than galaxies in the densest regime. I divide each volume-limited Main galaxy sample into two distinct populations, the early type and the late type, and observe that the environmental dependence of the SFR and SSFR of galaxies remains true at fixed morphology: the SFR and SSFR of galaxies in the densest regime is still preferentially lower than that of the ones in the lowest density regime with the same morphological type. I also note that the environmental dependence of the SFR and SSFR of late-type galaxies is stronger than that of early-type galaxies. © 2010. The American Astronomical Society. All rights reserved.
Yan J.,Nanchang University
Food chemistry | Year: 2013
Xanthine oxidase (XO) catalyses hypoxanthine and xanthine to uric acid in human metabolism. Overproduction of uric acid will lead to hyperuricemia and finally cause gout and other diseases. Luteolin is one of the major components of celery and green peppers, its inhibitory activity on XO and their interaction mechanism were evaluated by multispectroscopic methods, coupled with molecular simulation. It was found that luteolin reversibly inhibited XO in a competitive manner with inhibition constant (Ki) value of (2.38±0.05)×10(-6) mol l(-1). Luteolin could bind to XO at a single binding site and the binding was driven mainly by hydrophobic interactions. Analysis of synchronous fluorescence and circular dichroism spectra demonstrated that the microenvironment and secondary structure of XO were altered upon interaction with luteolin. The molecular docking results revealed luteolin actually interacted with the primary amino acid residues located within the active site pocket of XO. Copyright © 2013 Elsevier Ltd. All rights reserved.
Qiu J.D.,Nanchang University
Protein and peptide letters | Year: 2010
The early determination of family for a newly found enzyme molecule becomes important because it is directly related to the detail information about which specific target it acts on, as well as to its catalytic process and biological function. Unfortunately, it is still a hard work to distinguish enzyme classes by experiments. With an enormous amount of protein sequences uncovered in the genome research, it is both challenging and indispensable to develop an automatic method for fast and reliably classifying the enzyme family. Using the concept of Chou's pseudo amino acid composition, we developed a new method that coupled discrete wavelet transform with support vector machine based on the amino acid hydrophobicity to predict enzyme family. The overall success rate obtained by the 10-cross-validation for the identification of the six enzyme families was 91.9%, indicating the current method could be an effective and promising high-throughput method in the enzyme research.
Hu B.,Nanchang University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
In this paper we discuss a new way to derive neutrino mixing patterns, which originates from the idea proposed in a recent article by Hernandez and Smirnov. Its applications to various cases are discussed. We first present the complete set of possible mixing patterns for the minimal case where unbroken residual symmetries of the Majorana neutrino and left-handed charged-lepton mass matrices obey some general assumptions that are also satisfied by many models based on discrete symmetries. We find that they are either well-known mixing patterns or phenomenologically disfavored ones. It shows clearly that, for full-mixing matrices to fit the mixing data with small or negligible corrections, it is necessary to go beyond the minimal scenario. We present an explicit formalism for a rather general nonminimal case. Some applications and phenomenological implications are discussed. Several new mixing patterns are derived. © 2013 American Physical Society.
Peng X.,Nanchang University
Journal of molecular and cellular cardiology | Year: 2013
FAT10 is a new member of the ubiquitin-like protein family with yet-to-be defined biological functions in the heart. Our objective was to determine the role of FAT10 in the heart. FAT10 is expressed in the normal human and murine hearts, as detected by qPCR and Western blotting. Expression of FAT10 is increased in the heart at the border zone of myocardial infarction and in cultured neonatal rat cardiac myocytes (NRCM) subjected to hypoxia/reoxygenation (H/R) stress. Lentiviral-mediated overexpression of FAT10 in NRCM reduced p53 (TP53) and its target miR-34a levels, while BCL2 level, a target of miR-34a, was increased and BAX level, a pro-apoptotic protein, was reduced. These changes were associated with reduced apoptosis, detected by FACS analysis of annexin-V expression and TUNEL assay, in response to H/R injury. Knock down of FAT10 by shRNA targeting had the opposite effects. Likewise, lentiviral mediated expression of miR-34a was associated with reduced BCL2 and increased BAX levels in NRCM and also reversed changes in BCL-2 and BAX levels observed upon over-expression of FAT10. Treatment of NRCM with proteasome inhibitor MG132 increased p53 and miR-34a levels and reduced BLC2/BAX ratio. These changes were not reversed upon over-expression of FAT10. Thus, FAT10 is upregulated in the heart and NRCM in response to H/R stress, which protects cardiac myocytes against apoptosis. The anti-apoptotic effects of FAT10 are associated with suppression of p53, probably through fatylation and proteasomal degradation, reduced miR-34a expression, and a shift in the BCL2/BAX proteins against apoptosis. Thus, FAT10 is a cardioprotective protein. Copyright © 2013 Elsevier Ltd. All rights reserved.
Liu X.R.,Nanchang University
The British journal of nutrition | Year: 2013
Industry-generated trans-fatty acids (TFA) are detrimental to risk of CHD, but ruminant-originated TFA have been reported as neutral or equivocal. Therefore, the total TFA amount should not be the only factor considered when measuring the effects of TFA. In the present study, we addressed whether a version of the TFA index that unifies the effects of different TFA isomers into one equation could be used to reflect CHD risk probability (RP). The present cross-sectional study involved 2713 individuals divided into four groups that represented different pathological severities and potential risks of CHD: acute coronary syndrome (ACS, n 581); chronic coronary artery disease (CCAD, n 631); high-risk population (HRP, n 659); healthy volunteers (HV, n 842). A 10-year CHD RP was calculated. Meanwhile, the equation of the TFA index was derived using five TFA isomers (trans-16 : 1n-7, trans-16 : 1n-9, trans-18 : 1n-7, trans-18 : 1n-9 and trans-18 : 2n-6n-9), which were detected in the whole blood, serum and erythrocyte membranes of each subject. The TFA index and the 10-year CHD RP were compared by linear models. It was shown that only in the erythrocyte membrane, the TFA isomers were significantly different between the groups. In the ACS group, industry-generated TFA (trans-16 : 1n-9, trans-18 : 1n-9 and trans-18 : 2n-6n-9) were the highest, whereas ruminant-originated TFA (trans-16 : 1n-7 and trans-18 : 1n-7), which manifested an inverse relationship with CHD, were the lowest, and vice versa in the HV group. The TFA index decreased progressively from 7·12 to 5·06, 3·11 and 1·92 in the ACS, CCAD, HRP and HV groups, respectively. The erythrocyte membrane TFA index was positively associated with the 10-year CHD RP (R 2 0·9981) and manifested a strong linear correlation, which might reflect the true pathological severity of CHD.
Wang Y.,Nanchang University |
Ni Y.,Nanchang University
Analytical Chemistry | Year: 2014
Transition metal chalcogenides, especially molybdenum disulfide (MoS 2), have recently attracted wide attention from researchers as graphene-analogous materials. However, until now, little literature has reported the synthesis of photoluminescent MoS2 materials and their applications in analytical chemistry. We herein presented a facile bottom-up hydrothermal route for the synthesis of photoluminescent MoS2 quantum dots (QDs) by using sodium molybdate and cysteine as precursors. The prepared MoS2 QDs were characterized by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and UV-vis spectroscopy. The MoS2 QDs were then used as photoluminescent probes to construct a photoluminescence (PL) quenching sensor for detection of 2,4,6-trinitrophenol (TNP). The TNP sensor presented a wide linear range from 0.099 to 36.5 μM with a high detection limit of 95 nM. Furthermore, the sensor displayed a high sensitivity toward TNP over other structurally similar compounds like 2,4,6-trinitrotoluene, p-chlorophenol, phenol, and 2,6-di-tert-butyl-4- methylphenol. To understand the origin of the high sensitivity, we assessed the emission wavelength-dependent PL quenching behavior of MoS2 QDs by the above five compounds using Stem-Volmer equation in detail. The results showed that the novel approach we put forward can satisfactorily explain the interaction mechanisms between MoS2 QDs and the five compounds, and the high sensitivity for TNP very likely originated from a combination of the PL resonance energy transfer, electronic energy transfer, and electrostatic interactions between MoS2 QDs and TNP. Finally, the sensor was successfully applied for detection of TNP in water samples and test papers. © 2014 American Chemical Society.
Nanchang University | Date: 2013-12-24
The present invention provides a treating method for a solution containing rare earth, wherein the method comprising: (1) performing a fine-grained clay adsorption on the solution containing rare earth with fine-grained clay, the conditions of the fine-grained clay adsorption allow that solution adsorbed by said fine-grained clay contains rare earth with a concentration calculated by rare earth oxides not higher than 1 mg/L; (2) performing a coarse-grained clay adsorption on the solution adsorbed by said fine-grained clay with coarse-grained clay, the conditions of coarse-grained clay adsorption allow that solution adsorbed by said coarse-grained clay contains rare earth with a concentration calculated by rare earth oxides not higher than 0.5 mg/L; the grain diameter of at least 90% of said fine-grained clay particles is smaller than the grain diameter of said coarse-grained clay particles, and the grain diameter of said fine-grained clay is within a range of 1-250 m, and the grain diameter of said coarse-grained clay is within a range of 150-1,000 m; and (3) desorbing rare earth from said fine-grained clay undergone the fine-grained clay adsorption and said coarse-grained clay undergone the coarse-grained clay adsorption. The rare earth may be effectively recycled by applying the above method.
Nanchang University | Date: 2016-07-05
A device for producing semi-solid slurry, including a height adjustment mechanism, a position adjustment mechanism, a melt protection mechanism, a support mechanism, a revolving pipe, guide mechanisms, thermally-adapted elastic supports, a driving mechanism of the revolving pipe, and a cooling module. The height adjustment mechanism is a box structure including an upper casing and a lower casing. The position adjustment mechanism includes a stationary rail and a moving rail support, and the stationary rail is fixed on the upper casing of the height adjustment mechanism. The melt protection mechanism includes a seal box including a base plate fixed on the moving rail support. The support mechanism includes a main support frame and an angle adjustment bracket, the main support frame is fixed on the base plate of the seal box, and the angle adjustment bracket is mounted on the main support frame.