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Weldability and liquation cracking behavior of ZhS6U superalloy during electron-beam welding

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 251-259页

作者： Arash Khakzadshahandashti Mohammad Reza Rahimipour Kourosh Shirvani Mansour Razavi Department of Ceramic Materials and Energy Research Center Department of Material and Renewal Energy Iranian Research Organization for Science and Technology (IROST)

The weldability of the ZhS6U nickel-based superalloy, which is prone to solidification cracking during electron-beam welding(EBW) repair processes, was investigated. The effects of two different pre-weld heat-treatment cycles on the final microstructure before and after welding were examined. Welds were made on flat coupons using an EBW machine, and the two heat-treatment cycles were designed to reduce γ′ liquation before welding. Microstructural features were also examined by optical and scanning electron microscopy. The results showed that the change in the morphology and size of the γ′ precipitates in the pre-weld heat-treatment cycles changed the ability of the superalloy to release the tensile stresses caused by the matrix phase cooling after EBW. The high hardness in the welded coupons subjected to the first heat-treatment cycle resulted in greater resistance to stress release by the base alloy, and the concentration of stress in the base metal caused liquation cracks in the heat-affected zone and solidification cracks in the weld area.

关键词： weldability ZhS6U superalloy electron beam welding heat-affected zone liquation cracking pre-weld heat treatment

Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

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Science China Chemistry 2025年第1期68卷 288-296页

作者： Shuai Liu Wen-Qiang Xu Ying-Tong Di Man-Cheng Tang Ding-Kang Chen Ming-Ming Cao Yao-Wen Chang Hong-Yu Tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han Guo Zi-Fei Xu Ying Zeng Yun-Dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词： metabolon Diels-Alder reaction semipinacol rearrangement biosynthesis notoamides spiro polycyclic alkaloids

Synthesis and characterization of collagen/PLGA biodegradable skin scaffold fibers

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Regenerative Biomaterials 2017年第5期4卷 309-314页

作者： Alireza Sadeghi-Avalshahr Samira Nokhasteh Amir Mahdi Molavi Mohammad Khorsand-Ghayeni Meysam Mahdavi-Shahri Materials research Department Iranian Academic Center for EducationCulture and Research(ACECR)Khorasan Razavi BranchMashhadIran

The aim of this study is to investigate the applicability of poly(lactic-co-glycolic acid)(PLGA)/collagen composite scaffold for skin tissue *** and collagen were dissolved in HFIP as a common solvent and fibrous scaffolds were prepared by electrospinning *** scaffolds were characterized by scanning electron microscopy(SEM),FTIR spectroscopy,mercury porosimetry,tensile strength,biocompatibility assays and *** and cell adhesion were tested for two cell line groups,human dermal fibroblast(HDF)and human keratinocyte(HaCat).SEM images showed appropriate cell adhesion to the scaffold for both cell *** assays indicated that the cell viability of HDF cells increased with time,but the number of HaCat cells decreased after 14 *** ultimate tensile strength was suitable for skin substitute application,but its elongation at break was rather *** successful clinical application of the PLGA/collagen scaffold,some properties especially mechanical strain needs to be improved.

关键词： tissue engineering composite scaffold biocompatibility skin cells

Serum γ-glutamyltransferase,alanine aminotransferase,and aspartate aminotransferase activity in iranian healthy blood donor men

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World Journal of Gastroenterology 2007年第6期13卷 889-894页

作者： Hossein Khedmat Farahnaz Fallahian Hassan Abolghasemi Bashir Hajibeigi Zohre Attarchi Farshid Alaeddini Mohammad Taghi Holisaz Masoumeh Pourali Shahin Sharifi Nasrin Zarei Baqiyatallah University of Medical Sciences Iran iranian Blood Transfusion Organization research center Tehran Iran

AIM: To determine serum γ-glutamyltransferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activity, and to assess their correlation with demographic and clinical findings in healthy blood donors. METHODS: This cross-sectional study was performed in 934 male blood donors, aged 18 to 68 years, who consecutively attended Tehran blood transfusion service in 2006. All participants were seronegative for HBV or HCV infections, non alcohol users, and all underwent a standard interview and anthropometric tests. Clinical and biochemical parameters including AST, ALT, and GGT activities were determined. Patients taking drugs known to cause hepatic fat deposition were excluded. For AST, ALT, and GGT variables, we used 33.33 and 66.66 percentiles, so that each of them was divided into three tertiles. RESULTS: Mean AST, ALT, and GGT activities were 25.26 ± 12.58 U/L (normal range 5-35 U/L), 33.13 ± 22.98 (normal range 5-35 U/L), and 25.11 ± 18.32 (normal range 6-37 U/L), respectively. By univariate analyses, there were significant associations between increasing AST, ALT, or GGT tertiles and age, body weight, body mass index, and waist and hip circumferences (P < 0.05). By multiple linear regression analyses, ALT was found to be positively correlated with dyslipidemia (B = 6.988, P = 0.038), whereas ALT and AST were negatively correlated with age. AST, ALT, and GGT levels had positive correlation with family history of liver disease (B = 15.763, P < 0.001), (B = 32.345, P < 0.001), (B =24.415, P < 0.001), ***: Although we did not determine the cutoffs of the upper normal limits for AST, ALT, and GGT levels, we would suggest screening asymptomatic patients with dyslipidemia and also subjects with a family history of liver disease.

关键词： γ-glutamyltransferase Alanine aminotransrerase Aspartate aminotransferase Blood donor

Bioleaching of copper oxide ore by P seudomonas aeruginosa

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1130-1133页

作者： M.A.Shabani M.Irannajad A.R.Azadmehr M.Meshkini Department of Mining & Metallurgical Engineering Amirkabir University of Technology iranian Academic center for Education Culture and Research (ACECR)Branch of Amirkabir

Bioleaching is an environmentally friendly method for extraction of metal from ores. In this study, bioleaching of copper oxide ore by Pseudomonas aeruginosa was investigated. Pseudomonas aeruginosa is a heterotrophic bactermm that can produce various organic acids in an appropriate culture medium, and these acids can operate as leaching agents. The parameters, such as particle size, glucose percentage in the culture medium, bioleaching time, and solid/liquid ratio were optimized. Optimum bioleaching conditions were found as follows： particle size of 150-177 μm, glucose percentage of 6%, bioleaching time of 8 d, and solid/liquid ratio of 1：80. Under these conditions, 53% of copper was extracted.

关键词： copper ore treatment copper oxides bioleaching organic acids heterotrophic bacteria Pseudomonas aeruginosa

Using an Inhibitor to Prevent Plasticizer Migration from Polyurethane Matrix to EPDM Based Substrate

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Chinese Journal of Polymer Science 2019年第7期37卷 681-686页

作者： Hadi Rezaei-Vahidian Tohid Farajpour Mahdi Abdollahi Space Transportation research Institute Iranian Space Research CenterTehranIran Polymer Reaction Engineering Department Faculty of Chemical EngineeringTarbiat Modares UniversityTehranIran

The loss of adhesion between the propellant and insulator is one of the most important problems in solid propellant motors due to migration of plasticizer to interface of propellant and insulator. In this work, the polyurethane (PU) binder containing DOP plasticizer was used as a polymeric matrix and β-cyclodextrin (β-CD) was applied as inhibitor agent to prevent plasticizer migration from the PU matrix into the ethylene propylene diene monomer (EPDM) substrate. To increase the compatibility of β-CD and PU matrix, a derivative of β-CD has been synthesized using toluene diisocyanate (β-CD-TDI). The synthesized derivative was characterized by MALDI-MS and FTIR-ATR analyses. FTIR-ATR results confirmed the formation of bonding between β-CD and the polymeric network while the MALDIMS results showed that the synthesized derivative contained two β-CD and 7 TDI molecules bonded to β-CD. Investigation of the mechanical properties of PU modified by β-CD-TDI showed a decrease in tensile strength and an increase in elongation at break with increasing β-CD-TDI content. DMTA results showed a decrement in crosslinking density by increasing the β-CD-TDI content. Also, to investigate plasticizer migration, extraction of the DOP plasticizer from samples was performed using dichloromethane solvent and its concentration was measured by gas chromatography. The results of migration evaluation after four months showed that using β-CD as an inhibitor agent in the PU binder could prevent the migration of plasticizer to EPDM substrate.

关键词： Plasticizer migration β-Cyclodextrin Polyurethane

Zika virus:A review of literature

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Asian Pacific Journal of Tropical Biomedicine 2016年第12期6卷 989-994页

作者： Saeed Reza Jamali Moghadam Samaneh Bayrami Sepideh Jamali Moghadam Raheleh Golrokhi Fatemeh Golsoorat Pahlaviani SeyedAhmad SeyedAlinaghi Ziaeian Hospital Tehran University of Medical Sciences iranian research center for HIV/AIDS(IRCHA) Iranian Institute for Reduction of High-Risk BehaviorsTehran University of Medical Sciences

Zika virus(ZIKV) has two lineages:African and ***-borne flaviviruses are thought to replicate initially in dendritic cells and then spread to lymph nodes and the blood *** for infection through blood transfusion,sexual practices and perinatal transmission *** possible routes of perinatal transmission are during delivery,breastfeeding and by close contact between the mother and her ***,mucocutaneous exposures to the virus by infected blood or monkey bite,organ transplantation or hemodialysis are the other routes of ZIKV *** are two types of ZIKV infection;Zika fever and congenital *** presentation of Zika fever varies from asymptomatic infections to a self-limiting febrile disease with low grade fever,conjunctivitis,maculopapular rash,headache,retro-orbital pain and arthritis/arthralgia with periarticular edema,myalgia,vertigo,vomiting and *** clinical feature could be mistaken for dengue or chikungunya *** is the most important and frequently reported clinical picture of suspected congenital Zika *** tests are needed for diagnosis of ZIKV infection,because there is no known pathognomonic clinical,biochemical or radiological ***-PCR is the most wellliked *** samples are tested by immunoglobulin G ELISA with ZIKV *** are also tested by immunoglobulin M *** is no certified vaccine or therapeutic *** asymptomatic or uncomplicated patients,treatment is not necessary.

关键词： Zika virus Microcephaly Serologic tests Vaccine Treatment Supportive therapy

A new Monte Carlo code for absorption simulation of laser-skin tissue interaction

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Chinese Optics Letters 2007年第4期5卷 238-240页

作者： Afshan Shirklvand Saeed Sarlcar Marjaneh Hejazi Leila Ataie-Fashtami Mohammad Reza Alinaghizadeh Medical Physics & Biomedical Engineering Department Tehran University of Medical Sciences Tehran Iran Medical Physics & Biomedical Engineering Department Tehran University of Medical Sciences Tehran Iran research center for Science and Technology in Medicine Tehran Iran iranian Academic center for Education Culture and research Tehran Iran iranian center for Medical Laser Tehran Iran NOOR Medical Imaging center Tehran Iran

In laser clinical applications, the process of photon absorption and thermal energy diffusion in the target tissue and its surrounding tissue during laser irradiation are crucial. Such information allows the selection of proper operating parameters such as laser power, and exposure time for optimal therapeutic. The Monte Carlo method is a useful tool for studying laser-tissue interaction and simulation of energy absorption in tissue during laser irradiation. We use the principles of this technique and write a new code with MATLAB 6.5, and then validate it against Monte Carlo multi layer （MCML） code. The new code is proved to be with good accuracy. It can be used to calculate the total power absorbed in the region of interest. This can be combined for heat modelling with other computerized programs.

关键词： Laser beams Laser irradiation Medical imaging Multilayers Photon migration tissue

Climate Change, Risk and Grain Yields in China

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Journal of Integrative Agriculture 2013年第7期12卷 1279-1291页

作者： Rainer Holst Xiaohua Yu Carola Grün Courant research center 'Poverty Equity and Growth' Georg-August-University of Goettingen World bank

Adopting Just and Pope （1978, 1979） style yield functions, this paper proposes a method to analyze the impacts of regional climate change on grain production in China. We find that changes in climate will affect grain production in North and South China differently. Specifically, it emerges that a 1℃ increase in annual average temperature could reduce national grain output by 1.45% （1.74% reduction in North China and 1.19% reduction in South China）, while an increase in total annual precipitation of around 100 mm could increase national grain output by 1.31% （3.0% increase in North China and 0.59% reduction in South China）.

关键词： grain yield climate change yield risk China