Harbin, China
Harbin, China

Harbin Normal University is a university located in Harbin, Heilongjiang, P.R. China.HNU has 16 colleges and offers 46 academic majors. It offers undergraduate, graduate, and doctorate degrees. It has an international college which has enrolled students from over 20 countries.Daejin University, a South Korean private university, operates one of its two China campuses on the university grounds, with the other campus located at Soochow University in Suzhou. Daejin maintains its own building with accommodation and classrooms. Wikipedia.

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Ma H.,Harbin Normal University
International Journal of Computer Mathematics | Year: 2017

It is well known that the upper bounds of the weighted Moore–Penrose inverse(Formula presented.) play a fundamental role in the perturbation analysis for the weighted linear least squares problem. In this note, we provide a sharp estimation for (Formula presented.),(Formula presented.) Thus norm estimations for the weighted Moore–Penrose inverses of the acute perturbations can be improved uniformly. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Sun L.,Harbin Normal University | Zang S.,Harbin Normal University
Science of the Total Environment | Year: 2013

Atmospheric particle associated with pyrogenic polycyclic aromatic hydrocarbons (PAHs) poses serious threats to human health by inhalation exposure, especially in semiarid areas. Hence, the distributions of PAHs and particle size in two core sediments collected from Lake Lianhuan, Northeast China were studied. The sediments were dated radiometrically, and particle size distribution and PAH concentration were evaluated and potential human health risk was assessed. From 1980 to 2007, the dominant PAHs in the two cores were 2- and 3-ring PAHs, and the concentrations of 3-6 ring PAHs gradually increased from the early 1990s. Diagnostic ratios indicated that pyrogenic PAHs were the main sources of PAHs which changed over time from combustions of wood and coal to liquid fossil fuel sources. Fine particles (< 65 μm) were the predominant particle size (56-97%). Lacustrine source (with the peak towards 200-400 μm) and eolian sources derived from short (2.0-10 and 30-65 μm) and long (0.4-1.0 μm) distance suspension were indentified from frequency distribution pattern of particle size. Significant correlations between 3-6 ring PAHs (especially carcinogenic 5-6 ring PAHs) and 10-35 μm particulate fractions indicated that eolian particles played an important role in adsorbing pyrogenic PAHs. Petroleum source of PAHs was only identified during the 1980s in one core sediments, in which positive correlations between 2-ring PAHs and particulate fractions of > 125 μm were found. Future research should focus on the seven carcinogenic pyrogenic PAHs due to a rapidly increasing trend since 1995 based on the assessment of toxic equivalency factors. © 2013 Elsevier B.V.

Deng C.,Harbin Normal University | Zhang S.,Harbin Engineering University | Wu Y.,Harbin Normal University
Nanoscale | Year: 2015

Both high safety and low cost give aqueous rechargeable sodium-ion batteries (ARSB) the opportunity for application in stationary energy storage, but the low operating potential of the existing cathode materials limits its energy density. Here, we introduce a hydrothermal-assisted strategy to prepare the Na7V4(P2O7)4(PO4)/C nanorod and employ it as a novel high-property cathode material for ARSB. The hierarchical structure is formed by direct in situ carbonization of the surfactants (CTAB and oxalic acid) along with the crystallization of Na7V4(P2O7)4(PO4). The prepared Na7V4(P2O7)4(PO4) with a well-defined 1D nanostructure and uniform particle size is wrapped with a thin carbon layer. For the first time, its sodium intercalation chemistry in an aqueous electrolyte was investigated. Based on the reversible phase transformation and high sodium diffusion coefficient, it is demonstrated to be reliable in an aqueous electrolyte with the rapid ion transport capability. A pair of redox plateaus is observed in the charge and discharge curves at 0.961 and 0.944 V (vs. SCE) respectively with the capacity of 51.2 mA h g-1 at 80 mA g-1. Favored by the open ion channel and 1D morphology, the composite exhibits superior high rate capability and 72% of the capacity remains at 1000 mA g-1. The results not only demonstrate a high-property cathode material for ARSB, but also are helpful for design and synthesis of mixed-polyanion electrode materials with tailored architecture. This journal is © The Royal Society of Chemistry.

Deng C.,Harbin Normal University | Zhang S.,Harbin Engineering University
ACS Applied Materials and Interfaces | Year: 2014

Tailoring materials into nanostructure offers unprecedented opportunities in the utilization of their functional properties. High-purity Na 7V4(P2O7)4(PO 4) with 1D nanostructure is prepared as a cathode material for rechargeable Na-ion batteries. An efficient synthetic approach is developed by carefully controlling the crystal growth in the molten sodium phosphate. Based on the XRD, XPS, TG, and morphological characterization, a molten-salt assisted mechanism for nanoarchitecture formation is revealed. The prepared Na 7V4(P2O7)4(PO 4) nanorod has rectangle sides and preferential [001] growth orientation. GITT evaluation indicates that the sodium de/intercalation of Na7V4(P2O7)4(PO 4) nanorod involves V3+/V4+ redox reaction and Na5V3.5+ 4(P2O7) 4(PO4) as intermediate phase, which results in two pairs of potential plateaus at the equilibrium potentials of 3.8713 V (V 3+/V3.5+) and 3.8879 V (V3.5+/V4+), respectively. The unique nanoarchitecture of the phase-pure Na7V 4(P2O7)4(PO4) facilitates its reversible sodium de/intercalation, which is beneficial to the high-rate capability and the cycling stability. The Na7V4(P 2O7)4(PO4) cathode delivers 80% of the capacity (obtained at C/20) at the 10 C rate and 95% of the initial capacity after 200 cycles. Therefore, it is feasible to design and fabricate an advanced rechargeable sodium-ion battery by employment of 1D nanostructured Na 7V4(P2O7)4(PO 4) as the cathode material. © 2014 American Chemical Society.

Gao L.,Harbin Normal University | Qu F.,Harbin Normal University | Wu X.,Harbin Normal University
Journal of Materials Chemistry A | Year: 2014

We report a facile, two-step hydrothermal method to synthesize a WO 3@SnO2/carbon cloth heterostructure. Hybrid nanowire array/carbon cloth electrodes exhibit a high reversible capacity of 1000 mA h g-1 after 200 cycles at a current density of 0.28 C, much higher than that of pristine WO3 nanostructures, and enhanced rate capability at current densities ranging from 0.28 to 5 C. The superior electrochemical performance of the composite nanostructures can be ascribed to the incorporation of SnO2, which decreases the overall battery internal resistance and improves the conductivity of the composite electrodes. © the Partner Organisations 2014.

Zhang G.,Harbin Normal University
Chinese Geographical Science | Year: 2010

In the Sanjiang Plain, Northeast China, the natural wetland is undergoing a rapid conversion into agricultural land, which has resulted in drastic ecological changes in the region. To investigate the effects of different land uses on soil labile organic carbon, soils of Calamagrostis angustifolia wetland, Carex lasiocarpa wetland, dry farmland, paddy field, forest land and abandoned cultivated land were collected for measuring the contents of soil microbial biomass carbon (MBC), dissolved organic carbon (DOC), readily oxidizable carbon (ROC) and carbohydrate carbon (CHC). The results show that soil organic carbon contents follow the order: Carex lasiocarpa wetland>Calamagrostis angustifolia wetland>forest land>paddy field>dry farmland. The contents of MBC and DOC in Calamagrostis angustifolia and Carex lasiocarpa wetlands are significantly higher than those in other land use types. The contents of CHC and ROC are the highest in Calamagrostis angustifolia wetland and the lowest in dry farmland. The contents of all the labile organic carbon increase along with the years of abandonment of cultivated land. The ratios of MBC, DOC and ROC to SOC also follow the order: Carex lasiocarpa wetland>Calamagrostis angustifolia wetland>forest land>paddy field>dry farmland, while the ratio of CHC to SOC is paddy field>forest field>Carex lasiocarpa wetland>Carer lasiocarpa wetland>dry farmland. When natural wetlands were cultivated, the activity of soil organic carbon tends to reduce in some extent due to the disappearance of heterotrophic environment and the reduction of vegetation residue. Thus, the abandonment of cultivated land is an effective way for restoring soil organic carbon. © Science Press and Northeast Institute of Geography and Agroecology,.

Deng C.,Harbin Normal University | Zhang S.,Harbin Engineering University | Dong Z.,Harbin Normal University | Shang Y.,Harbin Normal University
Nano Energy | Year: 2014

1D nanostructured sodium vanadium oxide, i.e. Na2V6O16·nH2O, was introduced as a novel anode material for aqueous sodium ion batteries. A simple hydrothermal method is employed to prepare bundles of straight nanobelts whose crystals grow along the (010) direction. In each bundle, most nanobelts are aligned along the same direction. Sodium vanadium oxide hydrate has a layered structure, and that sodium ions are located at the interstices between layers. The solid-state diffusion coefficient of sodium ion in the bulk of Na2V6O16·nH2O is in the order of magnitude of 10-14cmS-1. The discharge/charge capacity fades quickly in the initial few cycles upon galvanostatic cycling. It is revealed by ex-situ XRD analyses that this fast capacity fading can be attributed to the irreversible phase transition which mainly occurs in the first discharge. A full aqueous sodium ion battery was built using Na2V6O16·nH2O as anode and Na0.44MnO2 as cathode. Although its charge capacity fades quickly in the initial few cycles and stabilizes in the following cycles, its discharge capacity is comparatively stable upon cycling. © 2014.

Gao J.F.,Harbin Normal University
International Journal of Computer Mathematics | Year: 2011

In this paper, we will study oscillations of numerical solutions for the neutral delay differential equation d/dt[y(t) + py(t - τ)] + qy(t + σ) = 0, where p ∈ ℝ and p ≠ 0, τ, q ∈ (0,+∞), σ ≥ 0. Conditions under which numerical solutions of the above differential equation are oscillatory are obtained. The condition that leads to oscillations of the linear θ-method is also given. To verify our results, we give numerical experiments. © 2011 Taylor & Francis.

Tan L.,Harbin Engineering University | Zhang S.,Harbin Engineering University | Deng C.,Harbin Normal University
Journal of Power Sources | Year: 2014

Lithium iron pyrophosphate has drawn great attention because of its interesting physical and electrochemical properties, whereas its high rate capability is far from satisfactory. We synthesize nano-Li2FeP2O7/C with hierarchical pore via a low cost method which uses iron powder instead of Vitamin C as the reducing agent. The hierarchical pore is constructed through a "combustion" mechanism according to the thermogravimetric and morphological characterizations. The phase-pure nanoparticles of Li2FeP2O7 are embedded in the three-dimensional network of amorphous carbon. The hierarchical pore together with the two-dimensional diffusion channel of lithium in Li2FeP2O7 is beneficial to lithium diffusion capability which is evaluated by the lithium diffusion coefficients calculated from the results of GITT measurements. The fast lithium intercalation chemistry facilitates the reversible de/intercalation of lithium, resulting in the high cycling stability and rate-capability. After 100 cycles at the current density of 1C, 93.8% of the initial capacity is retained. The discharge capacity is 62.1 mAh g-1 at the current density of 4C. Therefore, the hierarchically porous nano-Li2FeP2O7/C is a promising cathode material for advanced rechargeable lithium ion battery. © 2014 Elsevier B.V. All rights reserved.

Gai S.,Harbin Engineering University | Qu F.,Harbin Normal University | Yang P.,Harbin Engineering University
ACS Applied Materials and Interfaces | Year: 2013

A novel bifunctional (fluorescent, mesoporous) hollow sphere was prepared by coating luminescent YBO3:Eu3+ nanoparticles onto uniform hollow mesoporous silica spheres (HMSs), derived from an etching strategy using spherical Fe3O4 as templates. The composites exhibit typical mesoporous shells, large interior space, high surface area, and well dispersed nanospheres with controlled size. In addition, the textural properties including the specific surface and pore volume can be easily altered by simply tuning of the spherical Fe3O4 cores. Upon ultraviolet (UV) excitation, the composite shows the characteristic 5D0-7F1-4 red emission lines of Eu3+ even after loading of the model drug. The composite with a large surface area and cavity was used as the host for loading the anticancer drug doxorubicin hydrochloride (DOX). It is observed that the multifunctional composites exhibit an obvious sustained release property and released in texture- and pH-sensitive patterns. Particularly, the down-conversion (DC) fluorescence intensity of the bifunctional vehicle increases with the release of drug molecules, making it possible to track the position and the drug release amount of the drug carrier system and to detect them by the change of fluorescence intensity. © 2013 American Chemical Society.

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