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Highly diastereoselective cycloaddition of diarylnitrilimines to the c=S bond of (1R)-thiocamphor as a source of chiral spiro-1,3,4-thiadiazoles

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JOURNAL OF SULFUR cHEMISTRY 2013年第3期34卷 250-258页

作者： Itto, My Youssef Ait Feddouli, Amal Boutalib, Abderrahim Riahi, Abdelkhalek Daran, Jean-claude Univ Cadi Ayyad Fac Sci Semlalia Dept Chim Marrakech Morocco UFR Sci CNRS UMR 7312 Inst Chim Mol Reims F-51687 Reims 2 France CNRS Chim Coordinat Lab UPR8241 F-31077 Toulouse France

Highly diastereoselective 1,3-dipolar cycloaddition of in situ generated c,N-diaryl nitrilimines to (1R)-thiocamphor leads to chiral spiro-1,3,4-thiadiazolocamphane derivatives in good yields. The structures and stereochemistries of the new cycloadducts were fully established by spectroscopic methods including X-ray diffraction data. The diastereoselectivity observed in this reaction was explained by means of a brief theoretical study.

关键词： c N-diaryl nitrilimines (1R)-thiocamphor spiro-1 3 4-thiadiazoles diastereoselectivity X-ray analysis DFT calculations

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Influence of c-O-H Volatiles on Ni, co, and P Partition between Silicate Melt and Liquid Metal Fe Alloy at 4 GPa, 1550°c

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GEOcHEMISTRY INTERNATIONAL 2020年第6期58卷 670-686页

作者： Lukanin, O. A. Tsekhonya, T. I. Koltashev, V. V. Kononkova, N. N. Russian Acad Sci Vernadsky Inst Geochem & Analyt Chem GEOKhI Moscow 119991 Russia Russian Acad Sci Fiber Opt Res Ctr Moscow 119333 Russia

A set of experiments was carried out in the system NaAlSi3O8-FeO-NiO-coO-Sic-NaH(2)PO(4)at 1550 degrees c, 4 GPa, and oxygen fugacity (fO(2)) 0.5-2.9 log. units below the iron-wustite (IW) buffer to estimate how c-O-H components can affect Ni, co, and P partition between silicate melt and a liquid metallic phase at redox conditions under which the metallic phase is segregated into melting products of the early reduced mantles of the Earth and other planetary bodies. It has been established that the Ni, co, and P partition coefficientsD(\M)(met/sil)between silicate melts saturated with carbon and containing dissolved c-O-H volatiles (mainly in the form of OH groups, H(2)and cH4) at relatively oxidized conditions (fO(2)> IW - 1.5) correspond toD(\M)(met/sil)values expected of metal-silicate melt equilibrium in volatile-free systems at analogousP,T,f(O2), andnbo/tparameters. Under more reduced conditions (fO(2)<= IW - 2), the presence of c-O-H volatiles leads to a decrease inD(\M)(met/sil)for Ni and P compared to that in "dry" melts. This difference increases with decreasingfO(2)and reaches similar to 0.5 and more than one order of magnitude for Ni and P, respectively, atfO(2)= IW - 2.9. The effect of volatiles onD(co)(met/sil)is much weaker, and hence, a decrease infO(2)leads to thatD(Ni)(met/sil)andD(co)(met/sil)converge. The Raman spectra of the experimental glasses and their SIMS analyses for hydrogen show that water content (OH + H2O) in the melts decreases with decreasingfO(2), whereas the contents of cH(4)and complexes with c-H bonds significantly increases. The likely reasons for the decrease inD(\M)(met/sil)under strongly reduced conditions may be changes in the structure of the silicate melts and the origin of complex compounds of siderophile elements with volatiles in these melts.

关键词： experiment oxygen fugacity c Ni co P silicate melt siderophile elements silicate-metal partition

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Low residual stress c/c composite-titanium alloy joints brazed by foam interlayer

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cERAMIcS INTERNATIONAL 2022年第4期48卷 5260-5266页

作者： Guo, Wei Li, Kui Zhang, Hongqiang Zhu, Ying Shen, Xiaoyu Zhang, Lei Sun, Huawei Zhong, Sujuan Long, Weimin Beihang Univ Sch Mech Engn & Automat Beijing 100191 Peoples R China AECC Hunan Aviat Powerplant Res Inst Zhuzhou 412002 Peoples R China China Acad Space Technol Beijing 100081 Peoples R China Zhengzhou Res Inst Mech Engn State Key Lab Adv Brazing Filler Met & Technol Zhengzhou 450001 Peoples R China China Innovat Acad Intelligent Equipment Ningbo C Ningbo 315700 Peoples R China

Metallic foam was introduced as an interlayer to improve the performance of the brazed c/c composite-titanium alloy joint, and the interfacial microstructure and residual stress of the brazed joint were investigated. compared with the brazed joint without foam, introducing foam interlayer could achieve the uniform bonding interface, and Ag-based solid solution (Ag(s,s)) became more dispersed and smaller in the center of the brazing seam. The thickness of reaction layer close to c/c composite side was less than 1 mu m. Some cu-based solid solution (cu(s,s)) was detected, indicating that cu foam still existed after brazing. The residual stress and its distribution calculated by finite element method (FEM), and the residual stress of the brazed joint decreased from 293 MPa to 228 MPa. The introduction of the foam interlayer could obtain homogeneous microstructure, change stress distribution, and improve mechanical properties of the brazed joints.

关键词： Brazing Residual stress Foam interlayer c c composite Titanium alloy

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Effects of the c/N ratio on the microbial community and lignocellulose degradation, during branch waste composting

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BIOPROcESS AND BIOSYSTEMS ENGINEERING 2022年第7期45卷 1163-1174页

作者： Xie, Yuqing Zhou, Liuyan Dai, Jinping chen, Jing Yang, Xinping Wang, Xiaowu Wang, Zhifang Feng, Lei Xinjiang Acad Agr Sci Inst Microbiol Applicat Urumqi 830000 Peoples R China Xinjiang Key Lab Special Environm Microbiol Urumqi 830000 Peoples R China

Aerobic composting is an efficient and environmentally friendly method of converting organic waste into nontoxic fertilizers or soil quality enhancers. The quality of the resultant compost depends greatly upon the composition of the substrate used. The initial carbon-to-nitrogen (c/N) ratio of the substrate is an important factor affecting the composting process. This study elucidated how initial c/N ratios affect the biodegradation of lignocellulose, due to changes in microbial community structure. Four different c/N ratios (20:1, 25:1, 30:1, and 35:1) were examined during a 35-day composting process. The degradation of cellulose, hemicellulose, and lignin was highest (35.7%, 30.6%, and 19.1% respectively) at a 30:1 c/N ratio;after 30 days, the 25:1 c/N ratio ranked second in terms of lignocellulosic degradation rate. The 30:1 c/N ratio further promoted the growth of functional microorganisms responsible for lignocellulose degradation (Luteimonas, Sphingobium, Trichoderma, chaetomium, and Rosellinia), while the growth of dominant pathogenic microbes (Erwinia and Ulocladium) decreased significantly. These results confirm that the initial c/N ratio of the substrate has a significant effect on the microbial community and degradation of organic matter, during walnut branch composting. This process could therefore offer an alternative means of efficient recycling and recovery of waste branches.

关键词： composting Lignocellulose degradation c N ratio carbon emissions Microbial community

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Novel non-invasive score to predict cirrhosis in the era of hepatitis c elimination: A population study of ex-substance users in Singapore

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Hepatobiliary & Pancreatic Diseases International 2019年第2期18卷 143-148页

作者： Yue Zhao Prem Harichander Thurairajah Rahul Kumar Jessica Tan Eng Kiong Teo John chen Hsiang Department of Gastroenterology and Hepatology Changi General Hospital

Background: chronic hepatitis c infection is common among people with history of substance use. Liver fibrosis assessment is a barrier to linkage to care, particularly among those with history of substance users. The use of non-invasive scores can be helpful in predicting liver cirrhosis in the era of HcV elimination, especially in countries where transient elastography(TE) is not available. We compared the commonly used non-invasive scores with a novel non-invasive score in predicting liver cirrhosis in this population. Methods: HcV patients with history of substance use between 2011 and 2016 were analyzed. All patients had TE for liver fibrosis assessment. clinical performance of established non-invasive scores for fibrosis assessment and novel score were compared. Youden's index was used to determine optimal cut-off of the novel score. Results: A total of 579 patients were included. In multivariate logistic regression, cirrhosis on TE was associated with age( P = 0.002), aspartate aminotransferase(AST)( P = 0.004), and platelet count( P < 0.001), but not alanine aminotransferase(ALT)( P = 0.896). These form the components of modified AST-toplatelet ratio index(APRI) score. Modified APRI was superior to APRI in predicting cirrhosis(AUROc, 0.796 vs. 0.770, P = 0.007), but not fibrosis-4 score(FIB-4)( P = 1.00). Modified APRI at cut-off of 4 has sensitivity, specificity and negative predictive value(NPV) of 94.4%, 26.9% and 92.6%, respectively, and at 19, has sensitivity, specificity and positive predictive value(PPV) of 33.3%, 96.2% and 77.1%, respectively. FIB-4 has a NPV and PPV of 88.6%, 41.8% and 78.5%, 77.6%, at cut-off of 1.45 and 3.25, respectively. Using the cut-off of 4 and 14 for modified APRI, 32.5% of patients can be correctly classified and misses out only 5.6% of cirrhosis patients. conclusions: Modified APRI score is superior in predicting cirrhosis in HcV population, with 32.5% of the population being correctly classified using cut-off of 4 and 14.

关键词： Hepatitis c cirrhosis Fibrosis assessment AST-to-platelet ratio index Modified APRI Fibrosis-4 score

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A new clue for the pathogenesis of hepatitis c virus infection:Activation of the MAPK/ERK signaling initiated by envelope protein 2

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Science china(Life Sciences) 2003年第5期46卷 538-545页

作者：赵兰娟刘厚奇朱诗应冯根生戚中田 Department of Microbiology Second Military Medical University Shanghai 200433 China Department of Histology and Embryology Second Military Medical University Shanghai 200433 China Burnham Institute San Diego CA92037 USA

Since cell signal transduction plays an important role in disclosing the nature of human diseases, the pathogenesis of viruses may result from the disturbance of intracellular signal cascades caused by viral proteins. Hepatitis c virus (HcV) is a main causative agent of severe human liver disorders worldwide. So far, the mechanisms of HcV pathogenicity remain unclear. Envelope protein 2 (E2) of HcV is thought to be responsible for initiating virus attachment to host cells, which is a prerequisite of HcV infection. We assume that some early events of HcV pathogenic effects may result from the interaction of HcV E2 protein with its cellular receptor (human cD81), which could regulate cell proliferation and differentiation. To test this hypothesis, the effects of HcV E2 protein on MAPK/ERK pathway in Molt-4 and U937 cells with or without human cD81 expression were investigated. The results showed that HcV E2 protein could specifically activate the MAPK/ERK pathway, and such activation was inhibited by monoclonal antibodies against cD81 or HcV E2, serum antibodies from HcV infected patients, and upstream MEK1 inhibitor PD98059. Moreover, HcV E2-driven MAPK/ERK or downstream transcription factor Elk-1 activation was completely blocked in the presence of PD98059. These findings strongly suggest that the regulation of transmembrane signaling by HcV E2 protein via its receptor(s) on host cells might contribute to the development of HcV-related diseases.

关键词： hepatitis c virus, envelope protein 2, MAPK/ERK, signal transduction, pathogenesis.

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Modeling the Failure Time and Residual Strength of c/Sic composites under Stress-Oxidation Environment

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TRANSAcTIONS OF THE INDIAN cERAMIc SOcIETY 2020年第4期79卷 212-220页

作者： chen, Peng Niu, Xuming chen, Xihui Sun, Zhigang Zou, Pengjian Song, Yingdong Nanjing Univ Aeronaut & Astronaut Coll Energy & Power Engn Jiangsu Prov Key Lab Aerosp Power Syst Nanjing 210016 Peoples R China Sichuan Aerosp Syst Engn Inst Chengdu 610100 Peoples R China Minist Ind & Informat Technol Key Lab Aeroengine Thermal Environm & Struct Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing 210016 Peoples R China

Based on the oxidation kinetics of c/Sic composites at 900o-1200oc in stress-oxidation environment, a non-uniform model of oxidation has been suggested in this paper. combined with fiber notch model, curtin's strength model and BHE model, the non-uniform model is able to predict the failure time and residual strength of c/Sic composites accurately. Besides, the initial defects of the model (matrix coating crack and open porosity), the effects of coating were taken into account, and the fiber strength and broken ratio were analyzed. Furthermore, the effects of oxidation time, stress, temperature, Si c coating thickness and volume fraction of fiber on the failure time and residual strength were discussed, and the predicted results showed a good consistency with the experimental data.

关键词： c Si c composites Stress-oxidation Failure time Residual strength Predictive model

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Effect of the incorporation of Sic nanowire with double protective layers on Sic coating for c/c composites

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2023年第11期43卷 4636-4644页

作者： Xie, Aolin Zhang, Bei Ge, Yicheng Peng, Ke Xu, Ping Wang, Xiaodong Feng, Zhirong Yi, Maozhong Zhou, Zhe Cent South Univ State Key Lab Powder Met Changsha 410083 Peoples R China Changsha Univ & Sci & Technol Coll Mat Sci & Engn Changsha 410114 Hunan Peoples R China

To maintain the thermal stability of Sic nanowires during Sic coating fabrication process, carbon and Sic double protective layers were covered on the surface of nanowires. And Sic nanowires with double protective layers toughened Sic coating were prepared by pack cementation. The results showed that after introducing the Sic nanowires with double protective layers, the fracture toughness of the Sic coating was increased by 88.4 %. The coating protected c/c for 175 h with a mass loss of 3.67 %, and after 51 thermal shock cycles, the mass losses of the oxidized coating were 3.96 %. The double protective layers are beneficial to improve the thermal stability of nanowires, leading to good fracture toughness and thermal shock resistance of Sic coating. Sic nanowires consume the energy of crack propagation by fracture, pullout and bridging, leading to an increase in fracture toughness.

关键词： c c composites Sic nanowire-toughened Sic coating Double protective layers Fracture toughness Oxidation resistance

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Formation of composite powders and ceramics from β-Sic-cr²O₃-c mixtures

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JOURNAL OF MATERIALS SYNTHESIS AND PROcESSING 2001年第4期9卷 187-197页

作者： Vlasova, MV Kakazey, NG Gonzales-Rodriguez, JG Mondragon, JJS Prilutskii, EV Tomila, TM Isaeva, LP Timofeeva, II Bukov, AI Gordienko, SP UAEM Ctr Res Engn & Appl Sci Cuernavaca Morelos Mexico Natl Acad Sci Ukraine Inst Problems Mat Sci Kiev Ukraine

The phase-formation process in the disperse beta-Sic + SiO2 + cr2O3 + c system treated in vacuum at 1273, 1473, 1673, and 1873 K was studied by X-ray phase analysis, IR spectroscopy, EPR, and other methods. It was found that at treatment temperatures of 1273, 1473, and 1673 K, the major process is carbothermal reduction of cr2O3 and SiO2 with the formation of chromium carbosilicide and chromium carbide (cr3c2). At T = 1873 K, on the surface of the Sic particles, metastable chromium silicate forms on the base of SiO2 and cr2O3. The reduction of cr2SiO4 by silicon carbide is accompanied by the formation of crSi2, cr5Si3, and chromium carbosilicide. The phase composition of the products of interaction and their distribution over the volume of the composite powder and ceramic material are determined by the dispersion composition of the starting Sic powder and by the degree of development of reduction processes in local volumes of the disperse and compacted material.

关键词： beta-Sic cr2O3 SiO2 c interaction silicide formation

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A chromium carbide coating in-situ formed on c/c composites by the novel reactive wetting strategy to enhance oxidation resistance

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第14期42卷 6435-6444页

作者： Guo, Xiajun Si, Xiaoqing Liu, Yongxu Zhao, Wendi Wang, Xiaoyang Li, chun Qi, Junlei cao, Jian Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China

A chromium carbide (cr-c) coating in-situ formed on the c/c substrate is successfully prepared by a novel reactive wetting strategy. The interfacial microstructure and oxidation resistance of coated c/c composites are investigated in detail. The as-prepared coating mainly consists of cr23c6 and cr7c3, forming a tight joining with the c/c substrate. compared to uncoated samples, the oxidation weight loss of coated c/c composites is sub-stantially reduced at high temperatures. Furthermore, the hardness of coated c/c composites is significantly increased, enhancing their ability to resist external damage. This reactive wetting strategy can also be used to prepare uniform coatings on c/c composites with complex grooved structure or large size. Surprisingly, coated c/c composites possess a low weight gain of 3.7% due to thin coating (< 10 mu m), which can maintain their advantage of low density.

关键词： c c composites chromium carbide coating Oxidation resistance cr2O3

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