34 results on '"Chen, Chen‐Chen"'
Search Results
2. Efficient Semi‐Synthesis of Atypical Ubiquitin Chains and Ubiquitin‐Based Probes Forged by Thioether Isopeptide Bonds
- Author
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Chong Zuo, Yao Fu, Yi-Ming Li, Chen-Chen Chen, Xiao Hua, Zhongping Zhang, Jing Shi, Xianbin Meng, and Guo-Chao Chu
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biology ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Organic Chemistry ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Deubiquitinating enzyme ,chemistry.chemical_compound ,Ubiquitin ,Thioether ,biology.protein - Abstract
The development of powerful and general methods to acquire ubiquitin (Ub) chains has prompted the deciphering of Ub-mediated processes. Herein, the cysteine-aminoethylation assisted chemical ubiquitination (CAACU) strategy is extended and improved to enable the efficient semi-synthesis of atypical Ub chain analogues and Ub-based probes. Combining the Cys aminoethylation and the auxiliary-mediated protein ligation, several linkage- and length-defined atypical Ub chains including di-Ubs, K27C-linked tri-Ub, K11/K48C-branched tri-Ub, and even the SUMOlated Ub are successfully prepared from recombinantly expressed starting materials at about a 9-20 mg L-1 expression level. In addition, the utility of this strategy is demonstrated with the synthesis of a novel non-hydrolyzable di-Ub PA probe, which may provide a new useful tool for the mechanistic studies of deubiquitinase (DUB) recognition.
- Published
- 2019
3. Li4Ti5O12 nanosheets embedded in three-dimensional amorphous carbon for superior-rate battery applications
- Author
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Yonghui Sun, Chen-Chen Chen, Han-Kang Liu, N.Y. Yao, Xin Liang, Hongfa Xiang, and Xuyong Feng
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Battery (electricity) ,Materials science ,Mechanical Engineering ,Composite number ,Metals and Alloys ,Stacking ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,chemistry ,Amorphous carbon ,Chemical engineering ,Mechanics of Materials ,Impurity ,Phase (matter) ,Materials Chemistry ,Lithium ,0210 nano-technology - Abstract
Li4Ti5O12 nanosheets (LTONS) embedded in three-dimensional amorphous carbon (3DAC) are fabricated by a facile hydrothermal method. Structure and morphology analyses confirm that the Li2TiO3 impurity phase is effectively suppressed in LTONS@3DAC and that the stacking of LTONS is also significantly inhibited in the porous matrix of the 3DAC, helpfully increasing the lithium ion diffusion coefficient. Compared to LTONS, LTONS@3DAC has a greatly enhanced electrochemical performance, including superior rate capabilities of 146, 142, and 140 mAh g−1 at the current rates of 32, 48, and 64 C, respectively, and an excellent cycling stability of 140 mAh g−1 after 700 cycles at 8 C. Therefore, the LTONS@3DAC composite is promising for applications in superior-rate lithium-ion batteries.
- Published
- 2019
4. Chemical synthesis and structural analysis of guanylate cyclase C agonist linaclotide
- Author
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Pengcheng Mi, Qian Qu, Anjin Tao, Shuai Gao, Yi-Ming Li, and Chen-Chen Chen
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chemistry.chemical_classification ,Agonist ,010405 organic chemistry ,medicine.drug_class ,Peptide ,General Chemistry ,Guanylate cyclase C ,010402 general chemistry ,01 natural sciences ,Chemical synthesis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Peptide synthesis ,medicine ,Enantiomer ,Receptor ,Linaclotide - Abstract
Guanylate cyclase C (GC-C) is an important receptor protein expressed by intestinal epithelial cells, and its dysregulation leads to severe intestinal diseases. Linaclotide is a 14-amino acid peptide approved by the FDA for the treatment of irritable bowel syndrome with constipation (IBS-C), which activates guanylate cyclase C to accelerate intestinal transit. Drug molecule design based on structural information plays a crucial role and the activity of linaclotide still need to improve, while the structure of linaclotide remains unknown. In this work, linaclotide and its d -enantiomer were obtained through Fmoc solid phase peptide synthesis method and co-crystalized through racemic crystallization. The crystal structure showed that linaclotide has a tight, three-beta turns structure immobilized by three pairs of disulfide bonds.
- Published
- 2018
5. Racemic X-ray structure of L-type calcium channel antagonist Calciseptine prepared by total chemical synthesis
- Author
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Huasong Ai, Changlin Tian, Yi-Ming Li, Qian Qu, Shuai Gao, and Chen-Chen Chen
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010405 organic chemistry ,Chemistry ,Stereochemistry ,Calcium channel ,Antagonist ,Calciseptine ,General Chemistry ,Crystal structure ,010402 general chemistry ,Native chemical ligation ,Hydrazide ,01 natural sciences ,Chemical synthesis ,0104 chemical sciences ,chemistry.chemical_compound ,L-type calcium channel - Abstract
Snake toxin Calciseptine as a natural antagonist of L-type calcium channel has potential drug values, but its structural information remains unknown. Here, we report the total chemical synthesis of Calciseptine by using hydrazide based native chemical ligation. The crystal structure of Calciseptine was determined by racemic protein crystallography technique. Compared to the structure of its homologous family protein, we found that Calciseptine is adopting a typical three-finger structure.
- Published
- 2018
6. Large-scale production of high-quality graphene sheets by a non-electrified electrochemical exfoliation method
- Author
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Hao Zheng, Hongfa Xiang, Pengcheng Shi, Sheng Cheng, Yueda Wang, J.P. Guo, Xin Liang, and Chen-Chen Chen
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Materials science ,Graphene ,Graphene foam ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Exfoliation joint ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Propylene carbonate ,Electrode ,General Materials Science ,Graphite ,0210 nano-technology ,Faraday efficiency ,Graphene oxide paper - Abstract
Graphene materials have recently experienced rapid developments, but large-scale production of high-quality graphene is still desired. Electrochemical exfoliation method is considered as a promising approach to meet this requirement. Here we demonstrate a non-electrified electrochemical exfoliation method to produce high-quality graphene (NEEG) sheets. By direct electrochemical reaction between graphite powders and metallic Li in 1 M LiPF6/propylene carbonate electrolyte, continuous graphite exfoliation is achieved with a high yield of excess 80% without any consumption of electric energy. The as-prepared NEEG has high quality with few defects (ID/IG = 0.45), a high C/O ratio of 27.74 and excellent electronic conductivity of 102.5 S cm−1. As conductive additives in Li4Ti5O12 electrode for lithium ion batteries, NEEG contributes to higher capacity and initial coulombic efficiency than common thermally reduced graphene oxide. Given the advantages of NEEG, the non-electrified electrochemical exfoliation method is promising for the large-scale preparation of high-quality graphene sheets.
- Published
- 2018
7. Chemical Synthesis of Natural Polyubiquitin Chains through Auxiliary-Mediated Ligation of an Expressed Ubiquitin Isomer
- Author
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Yi-Ming Li, Qian Qu, Jian-Feng Huang, Chen-Chen Chen, Jing Shi, Man Pan, and Ling Xu
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biology ,010405 organic chemistry ,Stereochemistry ,Organic Chemistry ,010402 general chemistry ,Hydrazide ,Native chemical ligation ,01 natural sciences ,Biochemistry ,Chemical synthesis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Ubiquitin ,biology.protein ,Physical and Theoretical Chemistry ,Ligation - Abstract
An efficient method for the assembly of polyUb chains using auxiliary-modified Ub isomers is reported. This strategy takes advantages of auxiliary-mediated native chemical ligation between the distal Ub C-terminal hydrazide and the auxiliary of proximal Ub. Using removable protecting groups, Lys48-linked and Lys6-linked tri-Ub and even a mixed-linkage Lys6, Lys48-linked triUb in multimilligram quantities was made. These results demonstrate that this strategy yields natural polyubiquitin chains of desired length and linkage by using Ub isomer.
- Published
- 2017
8. MoO2 nanoparticle-modified Li4Ti5O12 as high rate anode material for lithium ion batteries
- Author
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Hongfa Xiang, Hao Zheng, H.L. Zou, Xuyong Feng, Yueda Wang, Han-Kang Liu, and Chen-Chen Chen
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Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Materials Chemistry ,Lithium titanate ,High-resolution transmission electron microscopy ,Process Chemistry and Technology ,Spinel ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Anode ,chemistry ,Chemical engineering ,Ceramics and Composites ,engineering ,Surface modification ,Lithium ,0210 nano-technology ,Molybdenum dioxide - Abstract
MoO2 nanoparticle-modified Li4Ti5O12 materials were prepared via a facile solution-based method. X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) analyses revealed that the MoO2 nanoparticles were anchored on the surface of spinel Li4Ti5O12, and energy dispersive X-ray spectroscopy (EDX) mapping indicated the MoO2 nanoparticles distributed uniformly. Compared with the pristine Li4Ti5O12, the appropriate amount of MoO2 on the surface of the Li4Ti5O12 could not only effectively reduce the electrochemical polarization of Li4Ti5O12, but also contribute to specific capacity for lithium storage. The 3% MoO2 modified Li4Ti5O12 exhibited excellent rate capability of 116 mA h g−1 at 10 C, and superior cycling performance of 124 mA h g−1 after 450 cycles at 5 C. Since the MoO2 modification process was easy to handle and the source of Mo has affordable costs, MoO2-modified Li4Ti5O12 would be promising for industrial application.
- Published
- 2017
9. Effect of the thickness of Ti intermediate layer on the microstructure and mechanical properties of the W/Ta multilayer composites
- Author
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Rui Liu, Chen-Chen Chen, S.Y. Yang, X. Xia, Z.H. Zhong, Y.R. Mao, Zhen Zhang, Y.C. Wu, and S. Wang
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Toughness ,Materials science ,Mechanical Engineering ,Delamination ,Composite number ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,Tungsten ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,Composite material ,0210 nano-technology ,Layer (electronics) ,Solid solution - Abstract
Mechanical properties of tungsten (W) multilayer composites can be modified by the toughening layers and interfacial microstructure between W layer and toughening layer. The W/Ta multilayer composite usually shows low tensile strength and toughness because of the low strength of Ta layers and large bonding strength between W layer and Ta layer. In order to improve the strength and toughness of the W/Ta multilayer composite, Ti intermediate layers with different thickness ranging from 30 µm to 100 µm have been added between W layer and Ta layer to get a kind of W/Ti/Ta/Ti multilayer composites. It can be found that the thickness of the Ti layer has a large effect on the microstructure and mechanical properties of the W/Ta multilayer composites. The solid solution with pure β-Ti and β-Ta are formed in the Ti layer when the thickness of Ti layer is lower than 50 µm. Ti layer composed of β-Ti, β-Ta and α precipitates is developed when the thickness of Ti layer is larger than 80 µm. The comprehensive mechanical properties of the W/Ta multilayer composites increase as the thickness of Ti intermediate layer increases. The tensile strength of the W/Ti/Ta/Ti multilayer composites is up to 642 MPa, which is much higher than that of the W/Ta multilayer composites (274 MPa). The tensile strength of these multilayer composites can be evaluated by a modified mix model considering the interfacial stress concentration factor. As the fracture mechanism of the W/Ta multilayer composites is also modified by addition of the Ti layer, the toughness of the W/Ti/Ta/Ti multilayer composites is improved because of the delamination along with the W/Ti interface and plastic deformation of the Ti/Ta/Ti layer in plane stress condition.
- Published
- 2021
10. Effect of propylene carbonate-Li+ solvation structures on graphite exfoliation and its application in Li-ion batteries
- Author
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Pengcheng Shi, Xiao-Lin He, Chen-Chen Chen, Zhao-Ming Xue, M. Lin, Hongfa Xiang, and Hongmei Zheng
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General Chemical Engineering ,Inorganic chemistry ,Solvation ,chemistry.chemical_element ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Exfoliation joint ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Propylene carbonate ,Fast ion conductor ,Lithium ,Graphite ,0210 nano-technology - Abstract
The effect of propylene carbonate (PC)-Li + solvation structures on graphite exfoliation was investigated over a range of concentrations of PC-based electrolytes. At low concentrations of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in PC (1.3 M and 2.1 M), the graphite anode was exfoliated. However, the graphite exfoliation could be effectively suppressed when the concentrations of dissolved LiTFSI were increased to 2.5 M and 3.3 M. The results of spectroscopic analyses and density functional theory (DFT) calculations revealed that electrochemical exfoliation of the graphite anode is closely associated with a special spatial configuration of Li + -(PC) n (1 ≤ n ≤ 4) solvation structures at various Li-salt concentrations and corresponding solid electrolyte interface (SEI) film formation mechanisms. When the concentration of LiTFSI increased from 1.3 to 3.3 M, the spatial configuration of Li + -(PC) n (1 ≤ n ≤ 4) solvation gradually changed from a tetrahedron (occupied space of 10.19 A) to planar (occupied space of 3.05 A), which reduced the structure change for co-intercalation into the graphite interlayers of Li + -(PC) n (1 ≤ n ≤ 4) solvates. Meanwhile, the affinity between Li + -(PC) n (1 ≤ n ≤ 4) solvation cations and TFSI − anions was increased, leading to the significant contribution of TFSI − anions to SEI formation on the surface of graphite. Additionally, Al corrosion was not of concern in concentrated LiTFSI electrolyte. The 3.3 M LiTFSI/PC concentrated electrolyte exhibits promising electrochemical performance in graphite||LiNi 1/3 Co 1/3 Mn 1/3 O 2 full cells.
- Published
- 2017
11. Influence of Li3BO3 additives on the Li+ conductivity and stability of Ca/Ta-substituted Li6.55(La2.95Ca0.05)(Zr1.5Ta0.5)O12 electrolytes
- Author
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Chen-Chen Chen, X.P. Wang, Lixiao Zhang, Qi-Wu Fang, Y.X. Gao, and J.F. Yang
- Subjects
Lithium borate ,Materials science ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,Energy Engineering and Power Technology ,02 engineering and technology ,Electrolyte ,Crystal structure ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Molar ratio ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
The cubic Ca/Ta-substituted Li6.55(La2.95Ca0.05)(Zr1.5Ta0.5)O12 (LLCZTO) electrolytes were synthesized at 800 °C with Li3BO3 as additives. The optimal amount of Li3BO3 and its influences on the microstructure, crystal structures, Li+ conductivity and the stability of the Li6.55(La2.95Ca0.05)(Zr1.5Ta0.5)O12 were studied by SEM, XRD and EIS. Among all the samples, when the molar ratio of Li3BO3 to the Li6.55(La2.95Ca0.05)(Zr1.5Ta0.5)O12 is 4:5, the highest Li+ conductivity of 1.33 × 10−4 S cm−1 at 30 °C is obtained. When the LLCZTO samples are exposed in air, the Li+ conductivity is deteriorated possibly owing to the side reactions between the LLCZTO and the H2O or CO2 in the air. The Li3BO3 addition can alleviate such deterioration of the Li+ conductivity.
- Published
- 2017
12. Electrospun Li3.9Cr0.3Ti4.8O12 nanofibers as anode material for high-rate and low-temperature lithium-ion batteries
- Author
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Chen-Chen Chen, Xin Liang, Xuyong Feng, Sheng Cheng, Hongfa Xiang, Hailin Zou, and Y. Jin
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Materials science ,Mechanical Engineering ,Metals and Alloys ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Electrospinning ,Grain size ,0104 chemical sciences ,Anode ,Surface coating ,Nanocrystal ,chemistry ,Chemical engineering ,Mechanics of Materials ,Nanofiber ,Materials Chemistry ,Lithium ,0210 nano-technology - Abstract
Li3.9Cr0.3Ti4.8O12 nanofibers with one-dimensional (1D) morphology and excellent electrical conductivity are prepared via a facile electrospinning technique. The as-prepared Li3.9Cr0.3Ti4.8O12 nanofibers exhibit excellent lithium storage performance with superior rate capability and low-temperature performance: 140 mAh g−1 at 10 C and 91 mAh g−1 at 50 C rates at room temperature, 100 mAh g−1 at 1 C rate at −20 °C. The superior electrochemical performance of Li3.9Cr0.3Ti4.8O12 nanofibers is attributed to the 1D nano-architectures composed of nanocrystals and the reduced grain size in Li3.9Cr0.3Ti4.8O12, both of which facilitate the Li+ ion transport. The Li3.9Cr0.3Ti4.8O12 nanofibers also have a high Ti3+ concentration and an in-situ surface coating layer of Li2CrO4, which could enhance intraparticle and interparticle electronic conductivities of Li3.9Cr0.3Ti4.8O12 grains, respectively.
- Published
- 2017
13. A semisynthetic Atg3 reveals that acetylation promotes Atg3 membrane binding and Atg8 lipidation
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Lei Liu, Chao-Jian Guan, Yi-Chao Huang, Huan Lan, Yi-Tong Li, Li Yu, Cong Yi, Man Pan, Yi-Ming Li, Chen-Chen Chen, and Shaojin Zhang
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0301 basic medicine ,Saccharomyces cerevisiae Proteins ,ATG8 ,Science ,Lysine ,General Physics and Astronomy ,Autophagy-Related Proteins ,Lipid-anchored protein ,Plasma protein binding ,Saccharomyces cerevisiae ,Ubiquitin-conjugating enzyme ,Endoplasmic Reticulum ,Models, Biological ,General Biochemistry, Genetics and Molecular Biology ,Article ,03 medical and health sciences ,Amino Acid Sequence ,Multidisciplinary ,Chemistry ,Endoplasmic reticulum ,Acetylation ,Esters ,General Chemistry ,Autophagy-Related Protein 8 Family ,Intracellular Membranes ,Native chemical ligation ,Lipids ,Cell biology ,030104 developmental biology ,Liposomes ,Ubiquitin-Conjugating Enzymes ,Protein Binding - Abstract
Acetylation of Atg3 regulates the lipidation of the protein Atg8 in autophagy. The molecular mechanism behind this important biochemical event remains to be elucidated. We describe the first semi-synthesis of homogeneous K19/K48-diacetylated Atg3 through sequential hydrazide-based native chemical ligation. In vitro reconstitution experiments with the semi-synthetic proteins confirm that Atg3 acetylation can promote the lipidation of Atg8. We find that acetylation of Atg3 enhances its binding to phosphatidylethanolamine-containing liposomes and to endoplasmic reticulum, through which it promotes the lipidation process., Acetylation of Atg3 regulates lipidation of Atg8 and therefore autophagy, but the molecular mechanisms remain unclear. Here, Li et al. semi-synthesize diacetylated Atg3, allowing them to show that acetylated Atg3 enhances Atg8 lipidation by promoting interaction of Atg3 with liposomes containing physiological levels of phosphatidylethanolamine.
- Published
- 2017
14. Synthesis of <scp>l</scp> ‐ and <scp>d</scp> ‐Ubiquitin by One‐Pot Ligation and Metal‐Free Desulfurization
- Author
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Changlin Tian, Chen-Chen Chen, Shuai Gao, Feng Wang, Yi-Ming Li, Hua Xiao, Yi-Chao Huang, and Ye-Hai Wang
- Subjects
Circular dichroism ,Molecular Conformation ,Peptide ,Crystallography, X-Ray ,010402 general chemistry ,01 natural sciences ,Chemical synthesis ,Catalysis ,chemistry.chemical_compound ,Ubiquitin ,Peptide synthesis ,Molecule ,Sulfhydryl Compounds ,Ligation ,Solid-Phase Synthesis Techniques ,chemistry.chemical_classification ,Fluorenes ,biology ,010405 organic chemistry ,Organic Chemistry ,General Chemistry ,Native chemical ligation ,Combinatorial chemistry ,0104 chemical sciences ,chemistry ,biology.protein ,Chemical ligation ,Peptides - Abstract
Native chemical ligation combined with desulfurization has become a powerful strategy for the chemical synthesis of proteins. Here we describe the use of a new thiol additive, methyl thioglycolate, to accomplish one-pot native chemical ligation and metal-free desulfurization for chemical protein synthesis. This one-pot strategy was used to prepare ubiquitin from two or three peptide segments. Circular dichroism spectroscopy and racemic protein X-ray crystallography confirmed the correct folding of ubiquitin. Our results demonstrate that proteins synthesized chemically by streamlined 9-fluorenylmethoxycarbonyl (Fmoc) solid-phase peptide synthesis coupled with a one-pot ligation-desulfurization strategy can supply useful molecules with sufficient purity for crystallographic studies.
- Published
- 2016
15. Effect of interlayers on the tensile behaviors of tungsten multilayered composites
- Author
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Y.C. Wu, Rui Liu, Liujun Cao, S. Wang, Z.H. Zhong, Chen-Chen Chen, M.Y. Xie, and X. Xia
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Toughness ,Materials science ,Mechanical Engineering ,Metals and Alloys ,Spark plasma sintering ,chemistry.chemical_element ,02 engineering and technology ,Tungsten ,Dissipation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Fracture toughness ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,Materials Chemistry ,Laminated composites ,Elongation ,Composite material ,0210 nano-technology - Abstract
Tungsten (W) laminate materials are very promising to improve the fracture toughness of tungsten. In this study, four kinds of tungsten laminated composites with different interlayers, including Ta, Ti, Ti/Ta/Ti, and W layers, are fabricated by spark plasma sintering (SPS). Compared with the W/W, W/Ti and W/Ta multilayer composites, the W/Ti/Ta composites exhibit the highest tensile strength (581 MPa) and elongation (7.9%). It shows that a gradual decrease of strength and a gradual increase of ductility from the W layer to the Ta layer can be obtained in the W/Ti/Ta multilayer composites. The tensile strength of these multilayer composites can be approximately predicted by the modified rule of mix. The toughening mechanism can be attributed to the energy dissipation caused by interfacial debonding, plastic deformation of interlayers, and crack bridging of the intermediate layer. The results show that the mechanical properties of the different tungsten-based multilayers are closely related to the toughening interlayers, which is beneficial to design tungsten laminates with high strength and toughness.
- Published
- 2020
16. The effect of tungsten content on the rolling texture and microstructure of Ta-W alloys
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Chen-Chen Chen, Z.H. Wu, S. Wang, D.H. Si, M.Y. Xie, Zhen Zhang, Y.C. Wu, and L.Y. Li
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010302 applied physics ,Materials science ,Mechanical Engineering ,Alloy ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,Tungsten ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Shear (sheet metal) ,chemistry ,Mechanics of Materials ,0103 physical sciences ,Volume fraction ,engineering ,General Materials Science ,Texture (crystalline) ,Deformation (engineering) ,Composite material ,Dislocation ,0210 nano-technology - Abstract
The effect of tungsten content on deformation texture and microstructure of Ta-W alloy is studied. It is found that the increase of tungsten content results in the strengthening of α-fiber and the weakening of γ-fiber in Ta-W alloys. The volume fraction of γ-fiber developed in Ta-10W alloy is lower than that in Ta-2.5W alloys. Meanwhile, a more significant through-thickness texture gradient is formed in Ta-10W alloy. The addition of tungsten has an important effect on the ability cross-slip of dislocations. Therefore, more dislocation loops and activated slip systems can be seen in Ta-2.5W alloy. The size of the dislocation cells in Ta-2.5W alloy is larger than that in Ta-10W alloy. As shear bands tends to appear in γ-fiber, the density of shear bands in the Ta-2.5W alloy is much higher than that of Ta-10W alloy at the same reduction strain. Meanwhile, the wavelength of the wavy shear bands in Ta-10W alloy is smaller than that in Ta-2.5W alloy. In Ta-10W alloy, new grains with Goss orientation can be seen in periodic shear bands developed in {111} orientations, which is different from that in Ta-2.5W alloy.
- Published
- 2020
17. Accelerated Fmoc solid-phase synthesis of peptides with aggregation-disrupting backbones
- Author
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Chen-Chen Chen, Yi-Ming Li, Yi-Chao Huang, Chao-Jian Guan, Qing-Xiang Guo, and Xiang-Long Tan
- Subjects
Fluorenes ,Hot Temperature ,biology ,Chemistry ,Air ,Organic Chemistry ,Kinetics ,Amides ,Biochemistry ,Combinatorial chemistry ,Dioxanes ,chemistry.chemical_compound ,Solid-phase synthesis ,Ubiquitin ,Amide ,Solvents ,biology.protein ,Solid-Phase Synthesis Techniques ,Physical and Theoretical Chemistry ,Peptides - Abstract
In this work, we describe an accelerated solid-phase synthetic protocol for ordinary or difficult peptides involving air-bath heating and amide protection. For the Hmsb-based backbone amide protection, an optimized acyl shift condition using 1,4-dioxane was discovered. The efficiency and robustness of the protocol was validated in the course of preparation of classical difficult peptides and ubiquitin protein segments.
- Published
- 2015
18. Facile synthesis of C-terminal peptide hydrazide and thioester of NY-ESO-1 (A39-A68) from an Fmoc-hydrazine 2-chlorotrityl chloride resin
- Author
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Yi-Chao Huang, Chen-Chen Chen, Jing Shi, Shuai Gao, Yang Li, and Si-Jian Li
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chemistry.chemical_classification ,Organic Chemistry ,Hydrazine ,Peptide ,Hydrazide ,Native chemical ligation ,Thioester ,Biochemistry ,Combinatorial chemistry ,Chloride ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,medicine ,Peptide synthesis ,Chemical ligation ,medicine.drug - Abstract
The NY-ESO-1 (A39-A68) peptide hydrazide was prepared through 9-fluorenyl-methoxycarbonyl solid-phase peptide synthesis (Fmoc SPPS) from a new 9-fluorenyl-methoxycarbonyl hydrazine 2-chlorotrityl chloride (Fmoc-hydrazine 2CTC) resin. The new resin was ideal for long-term storage and usage in Fmoc SPPS. Besides, the title peptide hydrazide could be transformed nearly quantitatively into the corresponding peptide thioester, which was both isolable and usable directly in native chemical ligation (NCL).
- Published
- 2014
19. Efficient synthesis of trypsin inhibitor SFTI-1 via intramolecular ligation of peptide hydrazide
- Author
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Yao He, Min Zhang, Chen-Chen Chen, Mu Yu, Jing Shi, Yi-Qun Chen, Yi-Ming Li, Changlin Tian, Qing-Xiang Guo, and Lin Xu
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chemistry.chemical_classification ,Oxidative folding ,Trypsin inhibitor ,Organic Chemistry ,Peptide ,Nuclear magnetic resonance spectroscopy ,Hydrazide ,Biochemistry ,Combinatorial chemistry ,Cyclic peptide ,chemistry.chemical_compound ,chemistry ,Intramolecular force ,Drug Discovery ,Chemical ligation - Abstract
Cyclic peptide trypsin inhibitor SFTI-1 was synthesized via intramolecular ligation of a linear peptide hydrazide with high yield. This cyclization strategy did not cause epimerization at the C-terminal Arg residue. CD spectrum and NMR spectroscopy analysis demonstrated that well-folded SFTI-1 could be obtained via standard oxidative folding process. Thus, we present a simple and cost-efficient strategy for the synthesis of SFTI-1.
- Published
- 2014
20. Trimethyl phosphite as an electrolyte additive for high-voltage lithium-ion batteries using lithium-rich layered oxide cathode
- Author
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Z.D. Li, Q.F. Yuan, Xiao-Hang Ma, Qingsong Wang, Chen-Chen Chen, Yan Zhang, and Hongfa Xiang
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Renewable Energy, Sustainability and the Environment ,Chemistry ,Inorganic chemistry ,Trimethyl phosphite ,Energy Engineering and Power Technology ,chemistry.chemical_element ,High voltage ,Electrolyte ,Cathode ,law.invention ,Ion ,chemistry.chemical_compound ,law ,Thermal stability ,Lithium ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Oxide cathode - Abstract
Lithium-rich layered oxide cathode is a promising high-capacity cathode material for high-energy lithium-ion batteries. However, to achieve its high capacity, the development of high-voltage electrolytes is essential. In this work, trimethyl phosphite (TMP) is investigated as an electrolyte additive for high-voltage lithium-ion batteries using Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode. When 1% TMP is introduced into the electrolyte, cycling performance and rate capability of the Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode are improved significantly. The Li/Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cell with the TMP-containing electrolyte exhibits high capacity retention of 81.3% after 100 cycles and good rate capability of 150 mA h g −1 at 5 C and 90 mA h g −1 at 10 C, while the capacity of the cell without TMP is 48 mA h g −1 at 5 C. Based on the measurements on impedance spectra and thermal stability, it is concluded that TMP can effectively deactivate the catalyzing effect of some transition metal ions on the surface of the Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode.
- Published
- 2013
21. Electrochemical investigations of the LiNi0.45M0.10Mn1.45O4 (M=Fe, Co, Cr) 5V cathode materials for lithium ion batteries
- Author
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You-Jie Yu, Yanyue Wang, Chen-Chen Chen, and G.B. Zhong
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Scanning electron microscope ,Spinel ,Inorganic chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Electrolyte ,engineering.material ,Electrochemistry ,Cathode ,law.invention ,symbols.namesake ,chemistry ,law ,engineering ,symbols ,Lithium ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Dissolution - Abstract
LiNi0.5Mn1.5O4 and LiNi0.45M0.10Mn1.45O4 (M = Fe, Co, Cr) powders are prepared and systematically investigated as 5 V cathode materials for lithium-ion batteries. X-ray diffraction, Raman spectroscopy and scanning electron microscopy are employed to study their structures. The electrochemical cyclic performance and rate capability at room temperature and 55 °C are characterized and compared. The results indicate that the introductions of Fe, Co or Cr ions favor the crystal structure of the spinel in a F d 3 ¯ m symmetry compared with a symmetry of P4332 for the un-doped LiNi0.5Mn1.5O4. Excellent cycle life is measured for these 5 V Co- and Fe-doped electrodes. When cycled at 1C rate, about 95.9%, 93.1% and 81.7% of their initial capacities can be retained after 500 cycles for LiNi0.45Co0.10Mn1.45O4, LiNi0.45Fe0.10Mn1.45O4 and LiNi0.45Cr0.10Mn1.45O4, respectively. Their electrochemical performances at 55 °C are also much better than the un-doped sample. Three possible capacity fading mechanisms including structural transformation, the dissolution of the spinel into the electrolyte, and the oxidation of the electrolyte are discussed. The decomposition of the electrolyte is regarded as the most important mechanism.
- Published
- 2012
22. Effects of Al substitution for Ni and Mn on the electrochemical properties of LiNi0.5Mn1.5O4
- Author
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G.B. Zhong, Zhong Zhang, Chen-Chen Chen, and Yanyue Wang
- Subjects
Chemistry ,Scanning electron microscope ,General Chemical Engineering ,Inorganic chemistry ,Spinel ,Infrared spectroscopy ,Quaternary compound ,engineering.material ,Electrochemistry ,X-ray crystallography ,engineering ,Cyclic voltammetry ,Powder diffraction ,Nuclear chemistry - Abstract
The effects of Al substitution for Ni or (and) Mn in LiNi 0.5 Mn 1.5 O 4 spinel on the structures and electrochemical properties are investigated. Powders of LiNi 0.5 Mn 1.5 O 4 , Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 , LiNi 0.475 Mn 1.475 Al 0.05 O 4 and Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 are synthesized by a thermopolymerization method. Their structures and electrochemical properties are studied by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, cyclic voltammetry and galvanostatic charge–discharge testing. The introduction of Al in these LiNi 0.5 Mn 1.5 O 4 samples has resulted in structure variation, and greatly improved their cyclic performance and rate capability. The effects of Al substitutions for Ni and Mn in the LiNi 0.5 Mn 1.5 O 4 are different. Compared with LiNi 0.5 Mn 1.5 O 4 , Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 demonstrates higher specific capacity at room temperature but faster capacity fading at elevated temperatures. Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 displays a lower discharge capacity but better capacity retention at 55 °C. Moreover, the cyclic performance and rate capability of the Ni-substituted Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 , Ni/Mn co-substituted LiNi 0.475 Mn 1.475 Al 0.05 O 4 and Mn-substituted Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 at room temperature are similar, and have improved substantially compared with the Al-free LiNi 0.5 Mn 1.5 O 4 sample.
- Published
- 2011
23. A simple gel route to synthesize nano-Li4Ti5O12 as a high-performance anode material for Li-ion batteries
- Author
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Xuezheng Song, Chen-Chen Chen, Ning Ding, and Dong Wang
- Subjects
Thermogravimetric analysis ,Materials science ,Lithium nitrate ,Scanning electron microscope ,Mechanical Engineering ,Analytical chemistry ,Titanate ,Anode ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Polymerization ,Mechanics of Materials ,law ,Differential thermal analysis ,General Materials Science ,Calcination - Abstract
Nano-Li4Ti5O12 powders were synthesized by a simple gel route with acrylic acid, tetrabutyl titanate, and lithium nitrate as the precursors that were made into gels through thermal polymerization. The Li4Ti5O12 powders were obtained by calcination of the gels at 700, 750, and 800 °C. They were characterized by thermal gravimetric analysis, differential thermal analysis, X-ray diffraction, and field emission scanning electron microscopy. The electrochemical performance of these nano-Li4Ti5O12 powders was examined with galvanostatic cell cycling. The average particle size of the 700-, 750-, and 800 °C-calcined powders is about 70, 120, and 400 nm, respectively. The 750 °C-calcined powder exhibits a high capacity of over 160 mAh/g after 100 cycles and a good rate capability with a capacity of 122 mAh/g even at 10C rate.
- Published
- 2009
24. Electrical and electrochemical properties of γ-Li2CuZrO4
- Author
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Y. Jin, Dalong Zhang, Xiantao Wei, and Chen-Chen Chen
- Subjects
Phase transition ,Chemistry ,Mechanical Engineering ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,Mineralogy ,Atmospheric temperature range ,Electrochemistry ,Electrochemical cell ,Mechanics of Materials ,Electrical resistivity and conductivity ,X-ray crystallography ,Materials Chemistry ,Lithium ,Cyclic voltammetry - Abstract
The γ-Li 2 CuZrO 4 with a double rock-salt structure, as a lithium-ion compound, has never been reported on their physical and physicochemical properties. The γ-Li 2 CuZrO 4 was prepared by a solid-state reaction process. X-ray diffraction was used to analyze the structure of the products. Its electrical properties were characterized by both DC and AC measurements in the temperature range from 133 to 1273 K. Cyclic voltammetry and galvanostatic cell cycling were also employed to evaluate its electrochemical performance. It is found to be a pure electronic semiconductor with a fairly high conductivity (10 −5 S/cm at 133 K, 10 −2 S/cm at 300 K and 10 −1 S/cm at 1173 K). The average activation temperature is 14.4 kJ/mol. When increasing the temperature above 1073 K, a phase transition from γ to β takes place. When reacting with lithium in an electrochemical cell, γ-Li 2 CuZrO 4 decomposes into three phases during the initial discharge process, and possesses a reversible capacity of about 70 mAh/g.
- Published
- 2008
25. Synthesis and electrochemical characterization of LiCo1/3Ni1/3Mn1/3O2 by radiated polymer gel method
- Author
-
J. W. Wen, Hewen Liu, Honge Wu, and Chen-Chen Chen
- Subjects
Materials science ,Scanning electron microscope ,Mechanical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Electrochemistry ,Microstructure ,Electrochemical cell ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Mechanics of Materials ,General Materials Science ,Lithium ,Lithium oxide ,Faraday efficiency ,Sol-gel - Abstract
Layered LiCo1/3Ni1/3Mn1/3O2 as a lithium insertion positive-electrode material was prepared by a radiated polymer gel method. The synthesis conditions and microstructure, morphology and electrochemical properties of the products were investigated by XRD, SEM and electrochemical cell cycling. It was found that the positive-electrode material annealed at 950 °C showed the best electrochemical property with the first specific discharge capacity of 178 mAh/g at C/6 and stable cycling ability between 2.8 and 4.5 V versus Li/Li+. The optimized LiCo1/3Ni1/3Mn1/3O2 exhibited rather good rate capability with the specific capacity of 173 mAh/g at 0.2C and 116 mAh/g at 4C under a fast charge and discharge mode in rate performance test.
- Published
- 2007
26. Nanosized α-Fe2O3 and Li–Fe composite oxide electrodes for lithium-ion batteries
- Author
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Tursun Bark, Hanping Ding, Chen-Chen Chen, and P.C. Wang
- Subjects
Thermogravimetric analysis ,Materials science ,General Chemical Engineering ,Composite number ,Inorganic chemistry ,Oxide ,chemistry.chemical_element ,Electrochemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,Polymerization ,Transmission electron microscopy ,law ,Calcination ,Lithium - Abstract
Nanosized α-Fe2O3 (ca. 50 nm) and Li–Fe composite oxides (ca. 29 nm) powders were synthesized via gel polymer route. The gels were obtained with thermal polymerization of acrylic acid solutions of iron and lithium nitrates. The calcination of these gels at temperatures from 300 °C to 500 °C results in α-Fe2O3 from Fe(NO3)3 precursor and Li–Fe composite oxides Li2O–Fe3O4–LiFeO2 from a mixed precursors of Fe(NO3)3 and LiNO3. Thermal gravimetric analysis, X-ray diffraction and transmission electron microscopy were used to investigate the precursors and products. The electrochemical performance of the Fe-based oxides was also evaluated. After 200 cycles, their capacity can be as high as 1300 mAh/g for α-Fe2O3 and 1400 mAh/g for Li–Fe oxide while the initial capacity loss is as low as 21.8%. The Li–Fe oxide electrodes exhibit better capacity retention than the α-Fe2O3 electrodes. They are interesting negative electrodes for high energy density lithium-ion batteries.
- Published
- 2007
27. In-situ thermal polymerization of rechargeable lithium batteries with poly(methyl methacrylate) based gel-polymer electrolyte
- Author
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Chen-Chen Chen, S. Xie, and Yu Zhou
- Subjects
Materials science ,Mechanical Engineering ,Radical polymerization ,Electrolyte ,Lithium hexafluorophosphate ,Poly(methyl methacrylate) ,Lithium battery ,chemistry.chemical_compound ,Polymerization ,Chemical engineering ,chemistry ,Mechanics of Materials ,visual_art ,Polymer chemistry ,visual_art.visual_art_medium ,General Materials Science ,Cyclic voltammetry ,Methyl methacrylate - Abstract
By heating the admixture of a commercial liquid electrolyte (LB302, 1 M solution of LiPF6 in 1:1 EC/DEC), methyl methacrylate (MMA) and benzoyl peroxide (BPO, initiator), a poly(methyl methacrylate) (PMMA) based gel-polymer electrolyte (GPE) was obtained. AC impedance spectroscopy and cyclic voltammetry were used to evaluate its ionic conductivity and electrochemical stability window. Rechargeable cells LiNi0.8Co0.2O2/Li and LiNi0.8Co0.2O2/graphite with this MMA based GPE were also fabricated via the in-situ thermal polymerization process. This GPE exhibits a high ionic conductivity (over 10−3S cm−1) at room temperature. It is stable in the voltage range between 0 and 4.2 V (vs. Li+/Li). A phenomenon of large initial cell impedance (LICI) was observed for the LiNi0.8Co0.2O2/Li cells but not in LiNi0.8Co0.2O2/graphite cells. After the first several cycles, the cell impedance decreases substantially and reversible charge–discharge capacity can be obtained. This in-situ polymerization method provides a way to produce GPE cells.
- Published
- 2006
28. Improving the electrochemical behavior of LiCoO2 electrode by mixed Zr–Mg doping
- Author
-
Chenbin Zhang, Hui Xu, Chen-Chen Chen, and S. Xie
- Subjects
Renewable Energy, Sustainability and the Environment ,Chemistry ,Doping ,Analytical chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Electrochemistry ,Dielectric spectroscopy ,chemistry.chemical_compound ,Iodometry ,Electrode ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Cyclic voltammetry ,Cobalt ,Lithium cobalt oxide - Abstract
A new class of LiCo 1− x Zr x /2 Mg x /2 O 2 ( x = 0, 0.02, 0.06, 0.10, 0.20) materials has been synthesized using a solution–combustion method with mixed acetates/nitrates as the starting materials. The structure of the synthesized oxides was analyzed using X-ray diffraction (XRD). Iodometry titration was used to measure the oxidation state of cobalt. The electrochemical performance of LiCo 1− x Zr x /2 Mg x /2 O 2 electrodes was analyzed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge cycling studies in the voltage range 2.7–4.2 V (versus Li metal). It is found that the maximum doping level ( x ) is around 0.06, above which Li 2 MgZrO 4 is formed as an impurity phase. The use of combined Zr–Mg doping has resulted in the decrease of the electrode impedance and increase of the specific capacity and the stability of 3.6 V plateau efficiency.
- Published
- 2005
29. Lithium insertion in naturally surface-oxidized copper
- Author
-
S. Xie, Xiang Wei, Chen-Chen Chen, Junshuo Zhang, and Yubin Xiang
- Subjects
Copper oxide ,Renewable Energy, Sustainability and the Environment ,Analytical chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Electrochemistry ,Copper ,Anode ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,Lithium ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Cyclic voltammetry ,FOIL method - Abstract
In order to investigate the effect of copper oxide naturally formed on copper as the common anode current collector and as an electrode additive, the electrochemical behavior of lithium insertion in three naturally surface-oxidized copper powders and one copper foil was studied. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), particle size distribution measurement, galvanostatic cell cycling and cyclic voltammetry were employed for structural and electrochemical characterization. Although the XRD analysis can only detect the presence of pure Cu phase, the XPS analysis reveals clearly the presence of a CuO layer on the copper powders or the copper foil. The thickness of this CuO layer is estimated as thick as 147 nm. The lithiation capacity associated with this CuO layer can reach 48 mAh/g for copper powders but only 1 mAh/g for the foil. This small capacity, or 5.2 × 10 −3 mAh/cm 2 per unit area of copper foil, is fortunately negligible compared with that of a common anode material in a lithium-ion cell; while the capacity associated with this CuO layer must be taken into account when using a copper powder as an additive to improve the cycling stability.
- Published
- 2004
30. Electrochemical evaluation and modification of commercial lithium cobalt oxide powders
- Author
-
S. Xie, Y.J Xiang, Junshuo Zhang, Chen-Chen Chen, You-Jie Yu, and Guoshun Jiang
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Scanning electron microscope ,Inorganic chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Cathode ,Lithium battery ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Lithium ,Lithium oxide ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Cobalt ,Cobalt oxide ,Lithium cobalt oxide - Abstract
As the cathode materials for rechargeable lithium batteries, five commercial lithium cobalt oxide powders have been investigated for a comparative study. The X-ray diffraction analysis indicates that all these powders exhibit the α-NaFeO 2 layered structure. The size distribution and morphology were analyzed by particle sedimentation method and scanning electron microscopy (SEM). Their electrochemical properties including cycleability and especially 3.6 V plateau efficiency, a recently required control parameter, are compared. Two kinds of modifications, i.e. Li 2 CO 3 coating and high-temperature treatment, have been applied to improve the electrochemical performance of one of these five powders. After the high-temperature treatment in air, cobalt oxidation-state becomes higher and Li(Li x Co 1− x )O 2 is formed. Both of the two modified means can significantly improve the 3.6 V-plateau efficiency through suppressing the cell impedance rise during cycling. A general discussion on the factors influencing the plateau efficiency is also given.
- Published
- 2004
31. Thin films of lithium manganese oxide spinel as cathode materials for secondary lithium batteries
- Author
-
Chen-Chen Chen, Jianglan Shui, Guoshun Jiang, and S. Xie
- Subjects
Materials science ,Scanning electron microscope ,General Chemical Engineering ,Inorganic chemistry ,technology, industry, and agriculture ,chemistry.chemical_element ,Electrochemistry ,Cathode ,law.invention ,Dielectric spectroscopy ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Electrode ,Lithium ,Lithium oxide ,Thin film - Abstract
The miniaturization of rechargeable lithium-ion batteries requires high quality thin-film electrodes. Electrostatic spray deposition (ESD) technique was used to fabricate LiMn2O4 thin-film electrodes with three different morphologies: sponge-like porous, fractal-like porous, and dense structures. X-ray diffraction (XRD) and scanning electron microscopy were used to analyze the structures of the electrodes. These electrodes were made into coin cells against metallic lithium for electrochemical characterization. Galvanostatic cycling of the cells revealed different rate capability for the cells with LiMn2O4 electrodes of different morphologies. It is found that the cells with LiMn2O4 electrodes of porous, especially the sponge-like porous, morphology better rate capability than those with dense LiMn2O4 electrodes. Electrochemical impedance spectroscopy (EIS) study indicates that the large surface area of the porous electrodes should be attributed to the smaller interfacial resistance and better rate capability.
- Published
- 2004
32. Exploration of Alnico alloy as a magnetic electrode material for lithium-ion batteries
- Author
-
S. Xie, Jianglan Shui, Guoshun Jiang, Chuhong Zhu, Chen-Chen Chen, Wei Liu, Shangquan Zhang, and Ying Yu
- Subjects
Alloy ,Analytical chemistry ,chemistry.chemical_element ,Alnico ,engineering.material ,Electrochemistry ,Magnetic susceptibility ,Anode ,lcsh:Chemistry ,Chemical engineering ,chemistry ,lcsh:Industrial electrochemistry ,lcsh:QD1-999 ,Electrode ,engineering ,Lithium ,Magnetic alloy ,lcsh:TP250-261 - Abstract
The search for a reliable indicator of state-of-charge and even the remaining energy of a lithium-ion cell is of great importance for various applications. This study was an exploratory effort to use magnetic susceptibility as the indicator. Magnetic Alnico alloy was investigated as an anode material for rechargeable lithium batteries. Both pristine and partially oxidized Alnico powders were made into electrodes. Structural characterization was performed on the Alnico electrodes by means of X-ray diffraction, scanning electron microscopy, and inductively coupled plasma analysis. The electrochemical cycling of cells made of the Alnico electrodes against lithium was measured. The first lithium intercalation capacity of a treated Alnico can be up to about 600 mAh/g, while a rather reversible capacity of up to 180 mAh/g can be obtained. The capacity increases with the extent of oxidation of Alnico. It was observed that the ac susceptibility of an electrode changes with depth-of-discharge (DOD). We have proposed an electrode model with a core-shell structure, which can explain this susceptibility vs. DOD relationship. Keywords: State-of-charge, Magnetic susceptibility, Lithium batteries, Electrode, Oxidation
- Published
- 2004
33. Thiol-assisted one-pot synthesis of peptide/protein C-terminal thioacids from peptide/protein hydrazides at neutral conditions
- Author
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Jing Shi, Hua-Jian Xu, Yi-Chao Huang, Yi-Ming Li, Chen-Chen Chen, Ling Xu, Qing-Xiang Guo, Changlin Tian, and Yong Zheng
- Subjects
chemistry.chemical_classification ,Protein chemical synthesis ,Molecular Structure ,Organic Chemistry ,One-pot synthesis ,Peptide ,Chemistry Techniques, Synthetic ,Hydrogen-Ion Concentration ,Biochemistry ,Combinatorial chemistry ,Amino acid ,Hydrazines ,chemistry ,Labelling ,medicine ,Thiol ,Sulfhydryl Compounds ,Physical and Theoretical Chemistry ,Neutral ph ,Amino Acids ,Peptides ,Protein C ,medicine.drug - Abstract
An efficient thiol-assisted one-pot synthesis of peptide/protein C-terminal thioacids was achieved by using peptide/protein hydrazides precursors at neutral pH and room temperature (about 20 °C). The transformation from hydrazides to thioacids was shown to be efficient for different C-terminal amino acids and was racemization-free. The in situ formed peptide-thioacids were further used for protein chemical synthesis and site-specific labelling successfully.
- Published
- 2014
34. ChemInform Abstract: Spinel Li4Ti5O12as a Reversible Anode Material Down to 0 V
- Author
-
H. Q. Nian, Xiaolin Yao, Chen-Chen Chen, and S. Xie
- Subjects
Diffraction ,Chemistry ,Ac impedance spectroscopy ,Electrode ,Spinel ,engineering ,Analytical chemistry ,General Medicine ,engineering.material ,Plateau (mathematics) ,Electrochemistry ,Current density ,Anode - Abstract
The electrochemical behavior of Li 1.33 Ti 1.67 O 4 was investigated as an anode material discharged to 0 V using X-ray diffraction (XRD), galvanostatic cell cycling and ac impedance spectroscopy. The XRD results indicate that the lattice framework of Li 1.33 Ti 1.67 O 4 is almost unchanged even after it is discharged to 0 V. The Li 1.33 Ti 1.67 O 4 electrode can be cycled in the voltage range between 0 and 3.0 V with excellent cyclability and a capacity of about 200 mAh/g. During the discharge process, a 0.75 V plateau is also observed in addition to the usual 1.5 V plateau. The capacity associated with the 0.75 V plateau varies with current density and temperature. The possible cause of this low potential plateau is discussed and attributed to a carbon-triggered-capacity (CTC) effect.
- Published
- 2009
Catalog
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