检索结果-内蒙古大学图书馆

NMR studies of the effects of axial ligand substitution by imidazole on the conformation of cytochrome c

Science china chemistry 1995年第6期38卷 649-657页

作者：邵伟平姚亦明唐文霞 State Key Laboratory of Coordination Chemistry Nanjing University Nanjing 210093 China

A series of 1D and 2D 1H NMR studies are presented, which aim at assigning the hyperfine shifted resonances of the heme and the spin systems of more than 20 amino acid side chains, and characterizing the heme and ligand environment of the low spin imidazole complex of cytochrome c. Some details of the structure in the heme pocket of the cytochrome c-imidazole complex are shownqualitatively to have changed relatively to the native oxidized protein. The orientation of the coordinated imidazole is also determined based on the interpretation of a number of NOEs.

关键词： imidazole complex of cytochrome c NMR axial ligand conformation.

来源：评论

学校读者我要写书评

暂无评论

Ti-Fe-Si/c composites as anode materials for high energy li-ion batteries

引用

ENERGY SOURcES PART A-REcOVERY UTILIZATION AND ENVIRONMENTAL EFFEcTS 2022年第2期44卷 5154-5171页

作者： Nuhu, Bage Alhamdu Adun, Humphrey Bamisile, Olusola Mukhtar, Mustapha Southwest Petr Univ Sch Chem & Chem Engn Chengdu Peoples R China Cyprus Int Univ Energy Syst Engn Dept Mersin 10 Nicosia Turkey Chengdu Univ Technol Coll Nucl Technol & Automat Engn Chengdu Sichuan Peoples R China Guangdong Univ Petrochem Technol Sch Econ & Management Maoming Chinese Provinc Peoples R China

In this study, Ti-Fe-Si composites were prepared by one step ball-milling method as anode materials for Li-ion batteries. The effects of ball-milling speed and time were studied by X-ray diffraction, electron microscopy, and Fe-57 Mossbauer spectroscopy. changes in the composition and microstructure of the composites were observed and related to the electrochemical performance. Increasing ball-milling speed led to the formation of FeSix alloys that reduced the specific capacity while increasing the ball-milling time improved the particle size morphology and homogeneity. Discharge/charge profiles for the first two cycles were carried out at 0.05c current rate (1c = 1260 mAh.g(-1)for Li3.75Si). The first discharge for Ti-Fe-Si showed a LixSi reaction plateau of 1100 mAh.g(-1), which were reversible and yielded columbic efficiency (cE) 77% and 90% in the first and second cycles, respectively. This capacity plateau indicated the insertion of about 3.25 Li into silicon. For the composite containing an additional 10% carbon SP, the theoretical capacity was about 1130 mAh.g(-1), the discharge curve showed that the first discharge plateau reaches 1030 mAh.g(-1) corresponding to 3.5 Li with the first cE was about 85%, and 98% for the second cycle. The addition of carbon to Ti-Fe-Si-c played a key role in capacity retention. The best results were obtained for the composite Fe/Ti/Si (1:1:2) with 10 wt% of carbon, ball-milled at 500 rpm for 48 hours. The specific capacities were about 900 mAh.g(-1) at c/5 and 700 mAh.g(-1) at 1c (c = 1200 mAg(-1)) with a capacity retention of about 90% for 100 cycles.

关键词： Ti-Fe-Si c Li-ion batteries ball milling anode capacity discharge charge

来源：评论

学校读者我要写书评

暂无评论

Validation of NeQuick TEc data ingestion technique against c/NOFS and EIScAT electron density measurements

引用

RADIO ScIENcE 2016年第7期51卷 905-917页

作者： Nigussie, M. Radicella, S. M. Damtie, B. Yizengaw, E. Nava, B. Roininen, L. Bahir Dar Univ Washera Geospace & Radar Sci Lab Bahir Dar Ethiopia Abdus Salam Int Ctr Theoret Phys Telecommun ICT Dev Lab Trieste Italy Boston Coll Inst Sci Res Chestnut Hill MA 02167 USA Sodankyla Geophys Observ Sodankyla Finland

This paper investigates a technique to estimate near-real-time electron density structure of the ionosphere. Ground-based GPS receiver total electron content (TEc) at low and high latitudes has been used to assist the NeQuick 2 model. First, we compute model input (effective ionization level) when the modeled slant TEc (sTEc) best fits the measured sTEc by single GPS receiver (reference station). Then we run the model at different locations nearby the reference station and produce the spatial distribution of the density profiles of the ionosphere in the East African region. We investigate the performance of the model, before and after data ingestion in estimating the topside ionosphere density profiles. This is carried out by extracting in situ density from the model at the corresponding location of c/NOFS (communication/Navigation Outage Forecast System) satellite orbit and comparing the modeled ion density with the in situ ion density observed by Planar Langmuir Probe onboard c/NOFS. It is shown that the performance of the model after data ingestion reproduces the topside ionosphere better up to about 824km away from the reference station than that before adaptation. Similarly, for high-latitude region, NeQuick 2 adapted to sTEc obtained from high-latitude (TromsO in Norway) GPS receiver and the model used to reproduce parameters measured by European Incoherent Scatter Scientific Association (EIScAT) VHF radar. It is shown that the model after adaptation shows considerable improvement in estimating EIScAT measurements of electron density profile, F-2 peak density, and height.

关键词： ionosphere NeQuick TEc ingestion c NOFS topside electron density EIScAT VHF

来源：评论

学校读者我要写书评

暂无评论

Oxidation behaviour of Sic ceramic coating for c/c composites prepared by pressure-less reactive sintering in wet oxygen: Experiment and first-principle simulation

引用

cERAMIcS INTERNATIONAL 2021年第11期47卷 15337-15348页

作者： Zhang, Pengfei Zhang, Yulei Gai, Wenhan chen, Guohui Northwestern Polytech Univ Shaanxi Prov Key Lab Fiber Reinforced Light Compo State Key Lab Solidificat Proc Xian 710072 Peoples R China

Sic ceramic coating, for prevention of c/c composites against oxidation, was prepared by pressure-less reactive sintering to investigate the oxidation behaviour in an oxidising environment containing water vapour at 1773 K. The experimental results demonstrated that the oxidation behaviour of porous Sic ceramics could be divided into two stages, following the parabolic model, which was attributed to the variation in the contact area involved in the oxidation reactions. During the entire oxidation process, water vapour could accelerate the oxidation of the Sic ceramics, according to the weight change. By first-principle calculations, the accelerated oxidation rate of the Sic ceramics was attributed to weakened Si?O and Al?O bonds in the formed glassy scale, which were caused by hydroxide radicals from the water. Atomic thermal motions at high temperature could lead to the breakage of the network structure, promoting the diffusion and solution of oxidising gases. When the as-prepared Sic ceramics were applied as anti-oxidative coatings for the c/c composites, the Sic ceramic coating and c/c matrix could be sealed and protected faster per unit time, because water vapour was beneficial to the formation of a glassy layer. The weight loss of the c/c matrix could be attributed to unsealed microcracks inside the Sic coating in the initial stage.

关键词： c c composites Sic ceramic coating Oxidation behaviour Wet oxygen First-principles Molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

Role of fiber-matrix adhesion at cFRP stage on microstructure and mechanical properties of c/c-Sic composite

引用

INTERNATIONAL JOURNAL OF APPLIED cERAMIc TEcHNOLOGY 2022年第1期19卷 79-90页

作者： Dai, Jixiang Zhang, Zhaofu Zu, Yufei Sha, Jianjun Dalian Univ Technol State Key Lab Struct Analyses Ind Equipment Dalian 116024 Peoples R China Dalian Univ Technol Key Lab Adv Technol Aerosp Vehicles Dalian Peoples R China Xian Aerosp Composites Res Inst Xian Peoples R China

In order to understand the role of fiber-matrix adhesion (FMA) at carbon fiber-reinforced polymer (cFRP) stage on the microstructure and mechanical properties of c/c-Sic composite via liquid silicon infiltration (LSI) process, the FMA was adjusted by thermal treatment of carbon fibers at different temperatures and evaluated by means of single fiber push-out technique. The microstructure was characterized by optical microscopy and scanning electron microscopy. The mechanical properties were measured by the double-notched shear test, three-point flexural test, and single edge-notched beam test, respectively. Results indicated that the microstructure and mechanical properties of c/c-Sic composite via LSI were closely associated with the FMA at cFRP stage. The microstructure of c/c-Sic composite fabricated by using the cFRP with high FMA presented nonhomogeneous distribution and concentration of Sic matrix. In contrast, the c/c-Sic composite fabricated by using the cFRP with low FMA, the high content of Sic distributed homogeneously and surrounded the fiber, which resulted in a strong bonded c-Sic interface. The strong c-Sic interface is detrimental to the fracture toughness, but it is beneficial to the improvement of oxidation resistance. To obtain desired mechanical properties of c/c-Sic composite, the control of interface bonding is important, which can be realized by modifying the FMA at cFRP stage.

关键词： carbon fiber c c-Sic composite ceramic matrix composites fiber-matrix bonding microstructure control

来源：评论

学校读者我要写书评

暂无评论

N-doped c/Si@DAMO composite material using PVP as the carbon source for lithium-ion batteries anode

引用

IONIcS 2021年第10期27卷 4185-4196页

作者： Liang, Junhua chen, Si Fan, Zhengqing Zheng, Songsheng Wang, Zhaolin Xiamen Univ Coll Energy Xiamen 361102 Peoples R China

Silicon (Si) material, with high specific capacity (4200 mAh/g) and low discharge voltage, is considered as one of the most ideal, promising, and alternative anode materials in next-generation lithium-ion battery (LIBs). In order to resolve the internal drawbacks of Si and reduce the process cost, the Si recycled from the kerf waste of photovoltaic industry was used as raw material. A silane-coupling agent 3-2 (2-sminoethylamino) propyltrimethoxysilane (DAMO) and a binder (PAA) was used to prepare Si@DAMO composite material with cross-linked net structure. Then, the polyvinyl pyrrolidone (PVP) containing N element was coated on the Si@DAMO. After carbonization, the c/Si@DAMO composite material with cross-linked net structure was obtained. The as-prepared c/Si@DAMO anode delivered an initial capacity of around 2841.6 mAh/g, and it remained a reversible capacity of 2066.7 mAh/g after 200 cycles at the current density of 0.1 c. At the rate testing from 0.1 to 1 c, the discharge capacities were 2593.39 mAh/g, 2362.95 mAh/g, 2082.08 mAh/g, 1882.44 mAh/g, 1704.57 mAh/g, and 1545.32 mAh/g, respectively. It retained 2084.88 mAh/g when back to 0.1 c charge rate after 60 cycles. Therefore, it suggests that the as-prepared c/Si@DAMO is a potential anode material for LIBs.

关键词： Lithium-ion batteries PVP c Si composite material cross-linked structure

来源：评论

学校读者我要写书评

暂无评论

Determination of fracture mechanics parameters J and c* by finite element and reference stress methods for a semi-elliptical flaw in a plate

引用

INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 2003年第7-8期80卷 565-571页

作者： Biglari, F Nikbin, KM Goodall, IW Webster, GA Univ London Imperial Coll Sci Technol & Med Dept Mech Engn London SW7 2BX England Amirkabir Univ Technol Dept Mech Engn Tehran Iran

The fracture mechanics parameters J and c* used, respectively, to describe ductile fracture and creep crack growth can be determined either by finite element methods or reference stress techniques. In this paper solutions for a partially penetrating semi-elliptical flaw in a plate subjected to tension and bending loading are considered. Estimates of J and c* are obtained from finite element calculations for a range of work-hardening plasticity and power law creep behaviours and from reference stresses derived from 'global' collapse of the entire cracked cross-section. comparisons are made with solutions taken from the literature for a range of loading conditions, plate geometries and crack sizes and shapes. Generally it is found that although there are significant variations between the different finite element solutions, satisfactory estimates of J and c* that are mostly conservative are obtained when the reference stress procedure is adopted. (c) 2003 Elsevier Ltd. All rights reserved.

关键词： fracture mechanics plate J c reference stress limit load flaws finite element

来源：评论

学校读者我要写书评

暂无评论

Does influent c/N ratio affect pollutant removal and greenhouse gas emission in wastewater ecological soil infiltration systems with/without intermittent aeration?

引用

WATER ScIENcE AND TEcHNOLOGY 2020年第4期81卷 668-678页

作者： Pang, Junling Yang, Mo Tong, Deli Fu, Xu Huang, Linli Sun, Bo Pan, Jing Shenyang Normal Univ Coll Life Sci Shenyang 110034 Peoples R China

Wastewater ecological soil infiltration system (WESIS) is a land treatment technology for decentralized wastewater treatment that has been applied all over the world. In this study, the pollutant removal, emission of greenhouse gases (GHGs) and functional gene abundances with different influent c/N ratios were evaluated in WESISs with/without intermittent aeration. Intermittent aeration and influent c/N ratio affect pollutant removal and GHG emission. Increased influent c/N ratio led to high total nitrogen (TN) removal, low cH4 and N2O emission in the aerated WESIS, which was different from the non-aerated WESIS. High average removal efficiencies of chemical oxygen demand (cOD) (94.8%), NH4+-N (95.1%), TN (91.2%), total phosphorus (TP) (91.1%) and low emission rates for cH4 (27.2 mg/(m(2) d)) and N2O (10.5 mg/(m(2) d)) were achieved with an influent c/N ratio of 12:1 in the aerated WESIS. Intermittent aeration enhanced the abundances of bacterial 16S rRNA, amoA, nxrA, narG, napA, nirK, nirS, qnorB, nosZ genes and decreased the abundances of the mcrA gene, which are involved in pollutant removal and GHG emission. Intermittent aeration would be an effective alternative to achieving high pollutant removal and low cH4 and N2O emission in high influent c/N ratio wastewater treatment.

关键词： aeration c N ratio greenhouse gas wastewater ecological soil infiltration system

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Fabrication of SiO@Graphite@c@Al2O3 as Anode Material for Lithium-Ion Batteries

引用

JOURNAL OF ELEcTRONIc MATERIALS 2024年第7期53卷 4261-4271页

作者： Hou, chunping Yue, Zeyu Zhai, Lidong Sun, Hehang Xie, Haidong Lu, Hui Wu, Jiandong Wang, Xingwei Hou, Jiao North Minzu Univ Coll Mat Sci & Engn Yinchuan 750021 Peoples R China Bolt New Mat Yinchuan Co Ltd Yinchuan 750002 Peoples R China Ningxia Res Ctr Silicon Target & Silicon Carbon N Yinchuan 750021 Peoples R China

In this study, SiO@graphite@c@Al2O3 (SiO@G@c@A) composites are synthesized by varying the content of Al2O3, and their morphology and structure and their electrochemical performance are investigated in detail. The results indicate that the SiO/G@c@A-2 composite exhibits a specific capacity of 977.1 mA h g(-1) at a current density of 0.1 A g(-1) with a coulombic efficiency of 71.15%. Even after 100 cycles at a current density of 0.5 A g(-1), it retains a delithiated specific capacity of 640.7 mA h g(-1) and a capacity retention rate of 73.56%. Moreover, when the current density is raised to 2 A g(-1), it maintains a delithiated capacity of 568.4 mA h g(-1) and a capacity retention rate of 58.51%. The excellent electrochemical performance is ascribed to the synergistic effect of different components. The inclusion of graphite enhances overall conductivity while mitigating the volume expansion of the SiO. The application of asphalt pyrolytic carbon as a coating effectively isolates the SiO from the electrolyte, further reducing volume expansion and enhancing conductivity. The introduction of Al2O3 can absorb trace amounts of hydrogen fluoride (HF) generated during charge and discharge processes. Additionally, it facilitates the formation of an AlF3 film on the particle surfaces, which hinders and decelerates electrolyte dissolution into the electrode. The prepared composites exhibit promising prospects as lithium-ion battery anode materials. [GRAPHIcS] .

关键词： SiO graphite c Al2O3 electrochemical performance

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：