The Crystal Structure and Superconducting Property of (Li0.8Fe0.2)OHFeSe1-xTex

Journal of Superconductivity and Novel Magnetism - (Li0.8Fe0.2)OHFeSe is a superconductor with high superconducting transition temperature (43 K) and stable in air, which is conducive to...     

高效液相色谱法测定纺织品中喹啉的质量浓度

建立了测定纺织品中喹啉质量浓度的高效液相色谱检测方法,用高效液相色谱仪对样品中的喹啉及其他组分进行分离,用二极管阵列检测器进行紫外光谱分析,用峰面积外标法进行定量。喹啉的检出限为10 mg/kg,回收率在80%~120%,精密度小于2%。结果表明,该方法线性良好,测试简单,回收率、精密度高,满足测试要求。     

Research on the sticking-sliding contact ratio in high-speed cutting of cupronickel B10

Journal of Mechanical Science and Technology - Accurate understanding of the frictional behavior at the tool-chip interface is critical for the cutting process. To quantitatively analyze the ratio...     

4-4’二氨基二苯甲烷合成催化剂研究进展

4-4’二氨基二苯甲烷作为聚氨酯工业的重要中间体,在国内及国际市场上的消费量逐年攀升。以苯胺和甲醛为原料合成4-4’二氨基二苯甲烷是目前主要的生产方法,该法主要采用盐酸作为催化剂,由于工艺过程在分离方面存在诸多不足,因此发展非均相催化剂体系成为该领域未来的趋势。对以甲醛和苯胺为原料合成4-4’二氨基二苯甲烷的固体催化剂进行综述,重点关注分子筛催化剂领域的进展。     

Research progress on chemical modification of silk fibroin and its applications北大核心CSCD

Mulberry silk is composed of the two major parts of two triangle-like silk fibroin fibers and sericin covering the fibers and a few lipids. After removing the sericin on the raw silk what is left is the silk fibroin fiber. Silk fibroin is the main part of silk accounting for about 75% of the total weight. Silk fibroin contains 18 natural amino acids such as glycine Gly alanine Ala serine Ser serine aspartic acid Asp and tyrosine Tyr . The secondary structure of silk fibroin has three main conformations α-helix β-fold and random coil. Under certain conditions the three conformations can transform into each other and change the mechanical properties of the silk fibroin material. Silk fibroin extracted from silk fiber is a natural polymer with biocompatibility and biodegradability. It can be further processed into different forms of materials nanoparticles films hydrogels sponges etc. It has been applied in many fields such as biomedicine and cosmetics. In order to meet the needs of different fields researchers have conducted further chemical modification treatment based on the original excellent properties of silk fibroin. Meanwhile the active groups on various amino acid residues in silk fibroin also provide chemical reaction sites for the chemical modification of silk fibroin. The chemical modification methods of silk fibroin mainly include amino acid residue modification macromolecular grafting modification and crosslinking reaction modification. Among them amino acid residue modification can modify protein amino acid residues by chemical reagents and some groups can be introduced into the side chains of silk fibroin macromolecules. Grafting modification of silk fibroin macromolecules is one of the main means to bind functional compounds to silk fibroin macromolecular chains. The properties of grafted silk fibroin are affected by the type and grafting rate of the grafts. The chemical crosslinking reaction modification of silk fibroin macromolecules is to make the macromolecular chains connected by covalent bonds and form a network structure by means of crosslinking agents enzymes or ultraviolet irradiation. The cross-linking reaction can not only form covalent bonds within and between the molecular chains of silk fibroin thus changing its structural properties and improving its stability but be used to form covalent bonds with other polymers. At present the chemical modification of silk fibroin is mainly applied in the fields of silk textiles biomedicine and environmental science. In the field of silk textiles graft copolymerization modification of vinyl and other monomers crosslinking agent modification and other methods are used to overcome the shortcomings of silk like being easy to wrinkle. The graft modified monomers mainly include ethylene methacrylate and methylacrylamide. The active groups on crosslinking agents such as polycarboxylic acid / anhydride and epoxide are covalently combined with carboxyl hydroxyl and amino groups on macromolecules of silk fibroin to improve the wrinkle resistance of silk fabrics. In the field of biomedicine silk fibroin materials with appropriate chemical modification have better biological activity drug delivery ability antimicrobial properties and mechanical properties. The optimization of these properties enables silk fibroin materials to show great potential in drug control delivery tissue regeneration and wound repair. The applied research in the field of environmental science mainly focuses on the adsorption separation and catalysis of impurities in water. Therefore the modification of amino acid residues grafting and cross-linking of protein macromolecules can change some important properties of silk fibroin and meet the requirements of various applications and functionalization of silk fibroin. In many fields of chemical modification and application of silk fibroin protein fruitful results have been achieved which has laid a good foundation for the further development of related fields and also shows that the chemical modification of silk fibroin material has great potential and application prospects. However there are still some problems that need to be overcome and further improved in the current chemical modification methods such as mild modification conditions and accurate adjustment of the degree of modification which will be the research direction of related fields in the future. © 2022 Authors. All rights reserved.     

Dopant-induced surface activation of ceria nanorods for electro-oxidation of hydrogen and propane in solid oxide fuel cells

Ceria is an excellent oxide catalyst to break H₂ in the absence of noble metals and has shown great promise for potential applications in diverse technological fields. The catalytic activity of ceria is critically linked to surface composition and structure. Herein, selective doping with moderate lanthanide ions is reported to regulate surface oxygen vacancies and bonded adsorbates of ceria nanorods so as to finely tune their activities toward electro-oxidation of H₂ and C₃H₈ in reduced-temperature solid oxide fuel cells. Lanthanide doped ceria nanorods are hydrothermally synthesized, and electrochemically evaluated as the anode catalysts for reduced-temperature SOFCs. Measurements of anode polarization resistances and fuel cell power densities show a catalytic activity in the order of Ce_0.8Pr_0.2O_2-δ < Ce_0.8Gd_0.2O_2-δ < Ce_0.8Sm_0.2O_2-δ. Probing the surface structure with hydrogen temperature-programmed reduction, UV-Raman and XPS reveals that such catalytic activities are essentially determined by surface reducibility, availability of surface oxygen vacancies and strongly bonded hydroxyls.