Beijing Research Institute of Chemical Defense

Beijing, China

Beijing Research Institute of Chemical Defense

Beijing, China
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Long F.,Renmin University of China | Zhu A.,Beijing Research Institute of Chemical Defense | Shi H.,Tsinghua University | Wang H.,Renmin University of China | Liu J.,Beijing Research Institute of Chemical Defense
Scientific Reports | Year: 2013

A structure-switching DNA optical biosensor for rapid on-site/in situ detection of heavy metal ions is reported. Mercury ions (Hg2+), highly toxic and ubiquitous pollutants, were selected as model target. In this system, fluorescence-labeled DNA containing T-T mismatch structure was introduced to bind with DNA probes immobilized onto the sensor surface. In the presence of Hg2+, some of the fluorescence-labeled DNAs bind with Hg2+ to form T-Hg2+ -T complexes through the folding of themselves into a hairpin structure and dehybridization from the sensor surface, which leads to decrease in fluorescence signal. The total analysis time for a single sample was less than 10 min with detection limit of 1.2 nM. The rapid on-site/in situ determination of Hg2+ was readily performed in natural water. This sensing strategy can be extended in principle to other metal ions by substituting the T-Hg2+ -T complexes with other specificity structures that selectively bind to other analytes.


Xu B.,Beijing Research Institute of Chemical Defense | Hou S.,China University of Mining and Technology | Cao G.,Beijing Research Institute of Chemical Defense | Wu F.,Beijing Institute of Technology | Yang Y.,Beijing Research Institute of Chemical Defense
Journal of Materials Chemistry | Year: 2012

Gelatin, a renewable animal derivative composed of various proteins, was used as a precursor for nitrogen-doped porous carbon with high surface areas for supercapacitors for the first time. The preparation procedure is very simple, including the carbonization of gelatin under inert atmosphere, followed by NaOH activation of the carbonized char at 600 °C for 1 h. The porosity and surface chemistry of the carbon depend strongly on the weight ratio of NaOH/char, with the specific surface area and nitrogen content varying between 323 and 3012 m 2 g -1 and between 0.88 and 9.26 at%, respectively. The unique microstructure and nitrogen functionalities enable the carbon to exhibit a high capacitance of up to 385 F g -1 in 6 mol L -1 KOH aqueous electrolytes, attributed to the co-contribution of double layer capacitance and pseudo-capacitance. It also shows excellent rate capability (235 F g -1 remained at 50 A g -1) and cycle durability, making it a promising electrode material for supercapacitors. This journal is © The Royal Society of Chemistry.


Xu B.,Beijing Research Institute of Chemical Defense | Yue S.,China University of Mining and Technology | Sui Z.,Beijing Institute of Technology | Zhang X.,Beijing Institute of Technology | And 3 more authors.
Energy and Environmental Science | Year: 2011

Graphene oxide, an intermediate during graphene synthesis by a modified Hummers's method, exhibits higher capacitance, up to 189 F g -1, than graphene due to an additional pseudo-capacitance effect of attached oxygen-containing functional groups on its basal planes. Taking its higher capacitance, lower cost and shorter processing time into consideration, graphene oxide may be a better choice than graphene as an electrode material for supercapacitors. © 2011 The Royal Society of Chemistry.


Xu B.,Beijing Research Institute of Chemical Defense | Zheng D.,Beijing University of Chemical Technology | Jia M.,Beijing University of Chemical Technology | Cao G.,Beijing Research Institute of Chemical Defense | Yang Y.,Beijing Research Institute of Chemical Defense
Electrochimica Acta | Year: 2013

Nitrogen-doped porous carbons are very simply prepared by direct pyrolysis of a nitrogen-containing organic salt, the tetrasodium salt of ethylenediamine tetraacetic acid for example, at 600-900 °C in an inert atmosphere without activation. The porosity and surface chemistry of the carbon depend strongly on the pyrolysis temperature. The surface area and pore volume increase with the pyrolysis temperature, and vary from 408 to 1171 m2 g-1 and 0.209 to 0.709 cm3 g-1, respectively. While the nitrogen content decreases from 8.59 at% for pyrolysis at 600 °C to 1.02 at% at 900 °C. The unique microstructure and nitrogen functionalities enable the carbon to exhibit a capacitance of 245 F g-1 in a 6 mol L -1 KOH aqueous electrolytes, which is attributed to the contributions of double layer capacitance and pseudo-capacitance, with an excellent rate capability (188 F g-1 remained at 20 A g-1) and cycle durability. © 2013 Elsevier Ltd. All rights reserved.


Miao L.-X.,Beijing Institute of Technology | Miao L.-X.,Beijing Research Institute of Chemical Defense | Wang W.-K.,Beijing Research Institute of Chemical Defense | Wang A.-B.,Beijing Research Institute of Chemical Defense | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Lithium-sulfur (Li-S) batteries have received significant attention in recent years because of their high theoretical specific capacity (1675 mA h g-1) and energy density (2600 W h kg-1). Many papers focus on cells that exhibit very high capacity per gram of sulfur, which contain sulfur contents well below 50% which greatly reduces their overall energy density per gram of cathode. Moreover, they do not address the issues of practical sulfur loading and large-scale technology for commercial applications. In general, the lower the sulfur content, the higher the sulfur capacity. In this paper, a high sulfur content (80% S) carbon-sulfur (P-AB@S) material with core-shell structure has been successfully synthesized by grafting of polymer electrolyte (polyethylene glycol, PEG) chains and depositing sulfur onto the surface of electronically conductive acetylene black (AB). The PEG chains are inserted into the sulfur layer to reinforce the material's structural stability. More importantly, with a cathode containing 66% sulfur and approximately 3 mg cm-2 sulfur loading on the electrode, P-AB@S as a cathode material for lithium sulfur batteries shows a specific capacity of 577 mA h g -1 after 500 cycles at 100 mA g-1 between 1.5 V and 2.8 V. Moreover, the preparation method of the P-AB@S composite is a facile, cost-effective and template-free method and easy to implement large-scale technology for commercial applications. © 2013 The Royal Society of Chemistry.


Xu B.,Beijing Research Institute of Chemical Defense | Duan H.,China University of Mining and Technology | Chu M.,China University of Mining and Technology | Cao G.,Beijing Research Institute of Chemical Defense | Yang Y.,Beijing Research Institute of Chemical Defense
Journal of Materials Chemistry A | Year: 2013

A very simple, activation-free method for preparing nitrogen-doped porous carbon with high surface area for supercapacitors by direct pyrolysis of a nitrogen-containing organic salt, ethylenediamine tetraacetic acid (EDTA) disodium magnesium salt, in an inert atmosphere is presented. As the pyrolysis temperature increases from 500 to 900 °C, both the BET surface area and pore volume of the disodium magnesium EDTA-derived carbons increase and reach up to 1811 m2 g-1 and 1.16 cm3 g-1, respectively, while the nitrogen content decreases from 11.14 at.% to 1.13 at.%. The carbon obtained at a moderate pyrolysis temperature of 700 °C possesses a balanced surface area (1258 m2 g-1) and nitrogen content (5.43 at.%), exhibits high capacitance (281 F g-1), good rate capability (196 F g-1 at 20 A g-1) and cycle durability in 6 mol L-1 KOH aqueous electrolytes. This journal is © The Royal Society of Chemistry.


Zhang Y.,Beijing Research Institute of Chemical Defense | Liu Y.,Beijing Research Institute of Chemical Defense
3rd International Symposium on Intelligent Information Technology and Security Informatics, IITSI 2010 | Year: 2010

Today collaborative filtering is the most successful recommender system technology. However, in traditional collaborative filtering algorithms, users' interest is considered to be static. That means, in these algorithms, ratings produced at different times are weighted equally, and changes in user purchase interest are not taken into consideration. For this reason, the system may recommend unsatisfactory items when users' interest has changed. To solve this problem, the time factor has been brought into collaborative filtering. In new algorithms, we have divided users' rating history into several periods, analyzed users' interest distribution in these periods and quantize every user's interest. At the same time, we find user's recent interest by setting a time window. With these two technologies, we propose a collaborative algorithm time period partition named TPPCF. Experiments have shown that our new algorithm TPPCF substantially improves the precision of item-based collaborative filtering. © 2010 IEEE.


Ni J.,Soochow University of China | Wang Y.,Beijing Research Institute of Chemical Defense
RSC Advances | Year: 2015

Lithium iron phosphate (LiFePO4) is an appealing cathode material for lithium ion batteries. However, the degradation of LiFePO4 in air presents an unavoidable challenge, due to the vulnerability of divalent Fe against oxygen attack. In this work, we have carried out comprehensive research on the thermal stability and temperature-driven evolution of nanocarbon modified LiFePO4 in air. The results show that LiFePO4 retains structural stability up to 250°C for short periods of exposure to air. At long exposure times, structural evolution occurs at a much lower temperature, 150°C. The structural evolution proceeds as the temperature increases, and finishes at 400°C. The final products are monoclinic Li3Fe2(PO4)3 and α-Fe2O3. A quantitative evolution map has been developed through electrochemical cyclic voltammetry and galvanostatic tests. The results show that the largest changes take place between 200 and 250°C. © The Royal Society of Chemistry 2015.


Wang X.,Beijing Research Institute of Chemical Defense
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2011

In order to improve the attenuation effect of oil fog smoke on 10.6 μm laser emission, the mass extinction coefficient to 10.6 μm laser emission and distribution rule of granularity of oil fog caused by superfine graphite and oil fog smoke which was produced by oil smoke producer were tested in flat and wide outfield. Experimental results show oil fog combined with superfine graphite has larger attenuation effect on 10.6 μm laser emission and bigger average diameter than pure oil fog. The average diameter increases 87.8% and the extinction coefficient to 10.6 μm laser emission increases 122%. By analysis, the extinction performance of oil fog smoke will be enhanced with the increase of the average diameter of the smoke's particles when the diameter is smaller than 10.2 μm. As a result, the extinction performance of oil fog to 10.6 μm laser emission may be remarkably improved by enhancing the smoke's granularity through producing oil fog combined with graphite particles which have a bigger diameter.


Zhang X.,Beijing Institute of Technology | Sui Z.,Beijing Institute of Technology | Xu B.,Beijing Research Institute of Chemical Defense | Yue S.,Beijing Research Institute of Chemical Defense | And 3 more authors.
Journal of Materials Chemistry | Year: 2011

Mechanically strong and electrically conductive graphene aerogels can be prepared by either supercritical drying or freeze drying of hydrogel precursors synthesized from reduction of graphene oxide with l-ascorbic acid, and the resulting graphene aerogels possess the specific capacitance of 128 F g -1 with superior rate performance. © 2011 The Royal Society of Chemistry.

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