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LiFePO4/c cathode material prepared with a spherical, porous, hollow Fe3(PO4)2/c composite as a precursor for lithium-ion batteries

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IONIcS 2019年第12期25卷 5669-5680页

作者： Ma, Zhiming Xiao, Rengui Liao, Xia Huang, Yu Guizhou Univ Sch Chem & Chem Engn Guiyang Guizhou Peoples R China

Spherical porous hollow Fe-3(PO4)(2)/c composites with graftonite crystals were prepared in a mixed solvent of water and ethylene glycol by the solvothermal method. Then, olivine-structured LiFePO4/c was successfully synthesized by a solid phase reaction using Fe-3(PO4)(2)/c as the precursor mixed with nanospherical Li3PO4. The experimental results show that different proportions of mixed solvents have important effects on the morphology and carbon content of Fe-3(PO4)(2)/c, which further influence the electrochemical properties of LiFePO4/c. compared with LiFePO4/c prepared with FePO4 as the precursor, LiFePO4/c prepared using Fe-3(PO4)(2)/c with a water/ethylene glycol ratio of 1:1 as the precursor shows a better electrochemical performance with a discharge capacity of 165 mAh/g and a capacity retention rate of 96% over 100 cycles at 0.5 c. Using porous hollow Fe-3(PO4)(2)/c as the precursor for preparing LiFePO4/c is beneficial to the lithium-ion escaping and embedding during the process of charging and discharging, enhancing the discharge capacity and cycle stability of the cathode material.

关键词： Porous and hollow Fe-3(PO4)(2) c LiFePO4 c Glucose Electrochemical performance

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Fabricating Nitrogen-Rich Fe-N/c Electrocatalysts through ceO2-Assisted Pyrolysis for Enhanced Oxygen Reduction Reaction

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cHEMELEcTROcHEM 2019年第15期6卷 4040-4048页

作者： Bai, Suohong Zhang, Xueqiong Yu, Ying Li, Jiefei Yang, Yang Wei, Hang chu, Haibin Inner Mongolia Univ Coll Chem & Chem Engn Inner Mongolia Engn & Technol Res Ctr Catalyt Con Hohhot 010021 Peoples R China

The electrochemical oxygen reduction reaction (ORR) is a central process of various energy conversion systems. Yet, searching non-noble-metal electrocatalysts with superior ORR performance is still a great challenge. Herein, ceO2-loaded Fe-N/c catalysts (Fe-N/c-ceO2) were prepared through a facile hydrothermal and pyrolysis method for enhanced ORR properties. The proper amount of ceO2 can induce the anchoring of N species during the pyrolysis process, and increase the N-containing active sites such as Fe-N-x. Moreover, ceO2 nanoparticles are capable of rapidly reducing the H2O2 intermediate in ORR, further boosting the durability of the catalyst. consequently, the Fe-N/c-ceO2 (1 %) catalyst delivers prominent ORR performance with a half-wave potential of 0.862 V and a diffusion limiting current density of 5.51 mA cm(-2) in 0.1 M KOH, which is superior than that of the Fe-N/c catalyst, and even comparable to that of commercial Pt/c catalyst. Furthermore, the long-term stability test of Fe-N/c-ceO2 (1 %) shows a negative shift of just 18 mV of the half-wave potential after 10000 cycles, which is much smaller than that of the Fe-N/c sample.

关键词： oxygen reduction reaction electrocatalysis Fe-N c ceO2 Fe-N-x active sites

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Electronic Structure and Optical-absorption Properties of c-, N-, and S-doped BiOcl: the First-principles calculations

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chinese Journal of Structural chemistry 2019年第4期38卷 509-523页

作者： YAO Wen-Zhi YAO Jian-Bin ZHANG Xia MA Ya-Hao Department of Environmental and Municipal Engineering North China University of Water Resources and Electric Power Institute for Computational Materials Science School of Physics and Electronics Henan University Department of Information Engineering North China University of Water Resources and Electric Power

Impurity formation energy, electronic structure, and photocatalytic properties of c-, N-, or S-doped BiOcl are investigated by density-functional theory plus U calculations(DFT + U). Results show that the doping effect of S is better than that of c or N on the tunable photocatalytic activities of BiOcl. At low concentration, S-doped BiOcl systems are the most stable under Bi-rich growth conditions because of their lower impurity-formation energy. compared with the electronic structures of S-doped BiOcl, c-or N-doped BiOcl have relatively deeper impurity energy levels appearing in their band gap(except Bi_(36)O_(35)Ncl_(36)), which may act as photogenerated carrier-recombination centers and reduce photocatalytic activity. At high concentration, S is substituted on the O lattice site system, whereas some S 3p states mix with the valence band; this mixture leads to an obvious band-gap decrease and continuum-state formation above the valence-band edge of BiOcl. Such activity is advantageous to photochemical catalysis response. compared with pure Bi Ocl and a low-concentration S-doped system, a high-concentration S-doped system shows an obvious redshift on the absorption edge and has better photocatalytic O_2 evolution performance.

关键词： BiOcl c N S doping the first-principles electronic structures visible light absorption

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Seismic retrofitting of gravity-loads designed r.c. framed buildings combining cFRP and hysteretic damped braces

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BULLETIN OF EARTHQUAKE ENGINEERING 2019年第6期17卷 3423-3445页

作者： Mazza, Fabio Mazza, Mirko Univ Calabria Dipartimento Ingn Civile I-87036 Cosenza Italy

Despite the effectiveness of carbon fibre reinforced polymers (cFRPs) and steel braces equipped with hysteretic dissipative devices (HYDBs) to improve the seismic performance of r.c. framed structures, the only use of cFRPs may be unsatisfactory for the retrofitting of buildings designed for gravity loads only while HDYBs may be unsuitable without a preliminary upgrading. The use of cFRP and HYDB as a combined technique for the seismic retrofitting of reinforced concrete (r.c.) buildings is investigated herein. To this end, two-, four- and eight-storey r.c. framed structures are designed with reference to the structural codes for r.c. buildings in force in Italy before and after 1971. A computer code for the nonlinear static and dynamic analysis of r.c. framed structures is modified to include cFRPs and HYDBs. Firstly, the nonlinear static analysis of the original test structures is carried with the aim of improving preliminarily strength and displacement capacities by applying cFRPs laminates, at the top and bottom sides of r.c. frame members, and cFRPs wraps, at the critical end zones of columns, respectively. Then, a displacement-based design procedure of HYDBs is adopted to complete the seismic retrofitting, starting from capacity curves of the upgraded test structures. To check the reliability of the combined cFRP-HYDB technique, nonlinear dynamic analysis of the original and retrofitted structures is performed considering two sets of seven near- and far-fault ground motions scaled to the seismic design level. Results highlight that the insertion of the HYDBs is effective in reducing the seismic demand of previously upgraded cFRP structures, with Post71 types generally performing better than Ante71 ones.

关键词： R c framed structures carbon fibre reinforced polymers Hysteretic damped braces Seismic upgrading Seismic retrofitting

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High electrochemical performance of Li4Ti5O12/c synthesized by ball milling and direct flaming of acetylene gas as anode for lithium-ion battery

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IONIcS 2019年第11期25卷 5315-5322页

作者： Noerochim, Lukman Maghfiroh, Amalia Ma'rifatul Widyastuti Susanti, Diah Priyono, Slamet Prihandoko, Bambang Sepuluh Nopember Inst Technol Dept Mat & Met Engn Surabaya 60111 Indonesia Indonesian Inst Sci Res Ctr Phys Serpong Indonesia

Li4Ti5O12/c has been successfully synthesized by a solid-state reaction method of Li2cO3 and TiO2 followed by direct flaming of acetylene gas. Li4Ti5O12 with 2-h milling time is indexed as single-phase crystal structure of Li4Ti5O12 (JcPDS 04-0477). The SEM results show particle sizes between 0.192 and 0.360 mu m with a spherical shape, but there is agglomeration due to high temperature when the direct flaming of acetylene gas process is applied. The desired carbon content by direct flaming of acetylene gas is still very low at 0.6% for 10 min and 0.9% for 20 min. Li4Ti5O12 with 10 min of direct flaming of acetylene gas has the highest specific discharge capacity of 210.61 mAh/g. This is attributed to the pure single phase and the higher conductivity of the sample. This result shows that Li4Ti5O12/c synthesized by ball milling and direct flaming of acetylene gas could be a good candidate as anode for lithium-ion battery.

关键词： Li4Ti5O12 c Ball milling Direct flaming Anode Lithium-ion battery

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Preparation of Li4Ti5O12/c composite by one-step solid state method

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FERROELEcTRIcS 2019年第1期548卷 34-41页

作者： Ma, Guangqiang cheng, Min Panzhihua Univ Panzhihua Peoples R China

The Li4Ti5O12/c composites were synthesized by one-step solid-phase reaction using metatitanic acid, lithium carbonate and sucrose as raw materials. The effects of the molar ratio of lithium to titanium, calcining temperature, calcination time, and sucrose content on the structure of Li4Ti5O12/c composites were studied. XRD, SEM, TEM and electrochemical performance tests were used to characterize the results. The results showed that n(Li):n(Ti) = 0.85, calcination temperature was 750 degrees c, calcination time was 6 h, and the sucrose addition amount was 30% of the total mass of raw materials. Under the conditions, the pure Li4Ti5O12/c composites can be synthesized. The particles are uniform, the particle size is 0.1-1 mu m, and the carbon envelopment is better. The specific capacity is up to 163.94 mAh/g at 0.1 c rate, and the theoretical specific capacity is 175 mAh/g very close.

关键词： Li4Ti5O12 c solid-phase method carbon package

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Facile synthesis and electrochemical properties of high tap density LiFePO4/c

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IONIcS 2019年第10期25卷 4589-4596页

作者： Wang, Xiaoyan Wen, Lizhi Zheng, Yi Liu, Hao Liang, Guangchuan Hebei Univ Technol Inst Power Source & Ecomat Sci Tianjin 300130 Peoples R China North China Univ Sci & Technol Qinggong Coll Tangshan 063000 Peoples R China Tianjin Sino German Univ Appl Sci Automobile & Rail Transportat Sch Tianjin 300350 Peoples R China Hebei Univ Technol Key Lab Special Funct Mat Ecol Environm & Informa Minist Educ Tianjin 300130 Peoples R China Hebei Univ Technol Key Lab New Type Funct Mat Hebei Prov Tianjin 300130 Peoples R China

A facile way of synthesizing LiFePO4/c with high tap density was introduced. LiFePO4/c composites were synthesized by a combination of wet ball milling, spray drying, and carbothermal reduction technology using inexpensive FePO4. The effect of sphericity of secondary microsphere on electrochemical properties and tap density of LiFePO4/c composite was systematically investigated. The sphericity of the secondary microsphere is controlled by particle size of primary particle with varying the ball grinding time. The composites were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), and tap density testing. The particle size of primary particle can effectively influence the sphericity of the secondary microsphere, and consequently change the electrochemical properties and tap density of LiFePO4/c. The optimum LiFePO4/c with high tap density of 1.68 g cm(-3) contains 2.1 wt% carbon and shows an excellent rate capability and cycle performance, with the initial discharge capacities of 164.0, 159.6, 154.9, 148.3, and 138.3 mAh g(-1) at 0.2 c, 0.5 c, 1 c, 2 c, and 5 c. The good electrochemical properties are attributed to the smaller particle, uniform primary particle size distribution, and the uniform carbon coating. The high tap density of LiFePO4/c composite is attributed to the better sphericity of secondary microsphere. With the primary particle size decreasing, the secondary microsphere sphericity is better.

关键词： LiFePO4 c Sphericity High tap density Electrochemical properties Particle size

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Histone demethylase KDM5A is transactivated by the transcription factor c/EBP and promotes preadipocyte differentiation by inhibiting Wnt/-catenin signaling

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JOURNAL OF BIOLOGIcAL cHEMISTRY 2019年第24期294卷 9642-9654页

作者： Guo, Liang Guo, Ying-Ying Li, Bai-Yu Peng, Wan-Qiu Tang, Qi-Qun Fudan Univ Key Lab Metab & Mol Med Minist Educ Dept Biochem & Mol BiolSch Basic Med Sci Shanghai 200032 Peoples R China Fudan Univ Dept Endocrinol & Metab Zhongshan Hosp Shanghai 200032 Peoples R China

beta-catenin signaling is triggered by WNT proteins and is an important pathway that negatively regulates adipogenesis. However, the mechanisms controlling the expression of WNT proteins during adipogenesis remain incompletely understood. Lysine demethylase 5A (KDM5A) is a histone demethylase that removes trimethyl (me3) marks from lysine 4 of histone 3 (H3K4) and serves as a general transcriptional corepressor. Here, using the murine 3T3-L1 preadipocyte differentiation model and an array of biochemical approaches, including chIP, immunoprecipitation, RT-qPcR, and immunoblotting assays, we show that Kdm5a is a target gene of ccAAT/enhancer-binding protein (c/EBP), an important early transcription factor required for adipogenesis. We found that c/EBP binds to the Kdm5a gene promoter and transactivates its expression. We also found that siRNA-mediated KDM5A down-regulation inhibits 3T3-L1 preadipocyte differentiation. The KDM5A knockdown significantly up-regulates the negative regulator of adipogenesis Wnt6, having increased levels of the H3K4me3 mark on its promoter. We further observed that WNT6 knockdown significantly rescues adipogenesis inhibited by the KDM5A knockdown. Moreover, we noted that c/EBP negatively regulates Wnt6 expression by binding to the Wnt6 gene promoter and repressing Wnt6 transcription. Further experiments indicated that KDM5A interacts with c/EBP and that their interaction cooperatively inhibits Wnt6 transcription. Of note, c/EBP knockdown impaired the recruitment of KDM5A to the Wnt6 promoter, which had higher H3K4me3 levels. Our results suggest a mechanism involving c/EBP and KDM5A activities that down-regulates the Wnt/-catenin pathway during 3T3-L1 preadipocyte differentiation.

关键词： adipogenesis ccAAT enhancer-binding protein (c EBP) histone demethylase Wnt signaling beta-catenin (B-catenin) epigenetics post-translational modification (PTM) obesity chromatin immunoprecipitation (chiP) 3T3-L1 preadipocyte adipogenesis c EBPbeta lysine demethylase 5A (KDM5A) Wnt beta-catenin pathway fat cell chIP-on-chip

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Preparation of LiFePO4/c via high-temperature ball-milling route and Box-Behnken design-based optimization

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IONIcS 2019年第10期25卷 4597-4606页

作者： Li, Xuetian cui, Yonghui Yu, Lina Shao, Hongmei Shao, Zhongcai Li, chuang Shao, Zhongbao Shenyang Ligong Univ Sch Environm & Chem Engn Shenyang 110159 Liaoning Peoples R China Shenyang Ligong Univ Sch Mat Sci & Engn Shenyang 110159 Liaoning Peoples R China Northeastern Univ Sch Met Shenyang 110819 Liaoning Peoples R China

LiFePO4/c cathode material was prepared via high-temperature ball-milling route with ultrasonic dispersion as mixing process using eutectic molten salt (0.76 LiOH center dot H2O-0.24 Li2cO3) as lithium source. Box-Behnken design was used to study the combined effects of ultrasonic time, ball-milling temperature, and ball-milling time on the discharge capacity to obtain the optimum predicted conditions. The optimum conditions were as follows: ultrasonic time was 63 min, ball-milling temperature was 638 degrees c, and ball-milling time was 7 h. LiFePO4/c prepared from the optimized experimental conditions exhibited a well electrochemical performance;its discharge capacity was 161.3 mAh g(-1) at a 0.1 c-rate which was in consistence with the predicted discharge capacity of 160.2 mAh g(-1). Moreover, its capacity retention rate achieved 93.6% at a 10 c-rate over 100 cycles.

关键词： LiFePO4 c cathode material High-temperature ball-milling route Box-Behnken design

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Effects of carbon source, c/N ratio, nitrate, temperature, and pH on N2O emission and functional denitrifying genes during heterotrophic denitrification

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JOURNAL OF ENVIRONMENTAL ScIENcE AND HEALTH PART A-TOXIc/HAZARDOUS SUBSTANcES & ENVIRONMENTAL ENGINEERING 2019年第1期54卷 16-29页

作者： Lee, Yun-Yeong choi, Hyungjoo cho, Kyung-Suk Ewha Womans Univ Dept Environm Sci & Engn 52 Ewhayeodae Gil Seoul 03760 South Korea

The effects of operational parameters such as carbon source, c/N ratio, initial nitrate concentration, temperature, and pH value on heterotrophic denitrification and functional denitrifying genes were evaluated. When methanol was used as the sole carbon source, complete denitrification was performed in a short time without nitrous oxide (N2O) emission. complete denitrification was performed at high c/N ratios (5.14 and 12.85) and low initial nitrate concentrations (75.9 and 151.6 mg N L-1). The denitrification rate was not temperature-sensitive in the range of 25-35 degrees c, but tended to decrease at a low pH of 5-6. The relationships between N2O emission and functional genes under various operational conditions were investigated by Pearson correlation and association network analyses. The c/N ratio was a key factor for N2O emission during the heterotrophic denitrification process. This information on the denitrification performance and its association with functional gene dynamics under various operational conditions is useful for N2O mitigation strategies for wastewater treatment processes.

关键词： Heterotrophic denitrification functional genes nitrous oxide c N ratio operational parameters

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