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combustion synthesis of c/MgAl2O4 composite powders using magnesium oxalate as carbon source

INTERNATIONAL JOURNAL OF APPLIED cERAMIc TEcHNOLOGY 2019年第3期16卷 1253-1263页

作者： Lv, Lihua Xiao, Guoqing Ding, Donghai Ren, Yun Yang, Shoulei Yang, Pan Hou, Xing Xian Univ Architecture & Technol Coll Mat & Mineral Resources Xian Shaanxi Peoples R China

In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, c/MgAl2O4 composite powders were prepared with Mgc2O4 center dot 2H(2)O, MgO2, Al2O3, and Al as raw materials via combustion method under argon atmosphere. The maximum adding amount of Mgc2O4 center dot 2H(2)O is 34.34 wt%. The phase compositions and microstructures of combustion products were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM)/EDX, and Raman spectroscopy. The results showed that the phases of products are mainly composed of MgAl2O4 and carbon. The prepared MgAl2O4 has granular and rod-like morphologies, and the free carbon (1.172 wt%) exists between particles of MgAl2O4. Moreover, the addition of Fec2O4 as catalyst in raw materials ratio would be beneficial for improving crystallization of in situ carbon generated in the products. The oxidation activation energy of the prepared c/MgAl2O4 composite powders was calculated as 143.01 kJ/mol which was 22.17% higher than that of carbon black/MgAl2O4 powders (117.06 kJ/mol), suggesting that the c/MgAl2O4 composite powders prepared by combustion synthesis have excellent oxidation resistance.

关键词： c MgAl2O4 composite powders combustion synthesis microstructure

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comprehensive determination of seven polyphenols in Eucommia ulmoides and its anti-oxidative stress activity in c. elegans

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JOURNAL OF FOOD MEASUREMENT AND cHARAcTERIZATION 2019年第4期13卷 2903-2909页

作者： Hou, Peilin Wang, Qing Qi, Wuqin Zhang, Yanqing Xie, Junbo Tianjin Univ Commerce Coll Biotechnol & Food Sci Tianjin 300134 Peoples R China Tianjin Univ Tradit Chinese Med Sch Chinese Mat Med Tianjin 301617 Peoples R China

In this study, an efficient HPLc method was developed and validated to determine seven polyphenols, i.e. chlorogenic acid, caffeic acid, protocatechuic acid, geniposide, rutin, quercetin and isorhamnetin, in different parts (leaves, barks and fruits) of Eucommia ulmoides. A Luna c-18 column (150 mm x 3.9 mm, 5.0 mu m) was applied and eluted with a gradient of acetonitrile-modified aqueous mobile phase (containing 1% acetic acid). 260 nm, 326 nm, and 360 nm were used as the detection wavelengths. With the developed method, these seven polyphenols were successfully assayed and their contents in different parts of E. ulmoides were compared. The results showed that these polyphenols displayed different distribution in the leaves, barks and fruits. chlorogenic acid, caffeic acid and rutin were their main common constituents. ABTS and DPPH free radical scavenging assay indicated that E. ulmoides displayed significant antioxidant activities in vitro. In addition, the extracts of the three parts can significantly increase the anti-oxidative stress level in wild-type c. elegans and prolong its lifespan, further demonstrating the antioxidant activity of Eucommia ulmoides.

关键词： Eucommia ulmoides chlorogenic acid caffeic acid Rutin Anti-oxidation c elegans

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Effects of Pore on Thermal Diffusivity and Thermal Radiation Properties of c/Sic composites at High Temperatures

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APPLIED cOMPOSITE MATERIALS 2019年第5-6期26卷 1411-1422页

作者： Wang, Fuyuan cheng, Laifei Liang, Shuhua Xian Univ Technol Sch Mat Sci & Engn Xian 710048 Shaanxi Peoples R China Xian Univ Technol Shaanxi Prov Key Lab Elect Mat & Infiltrat Techno Xian 710048 Shaanxi Peoples R China Northwestern Polytech Univ Sci & Technol Thermostruct Composite Mat Lab Xian 710072 Shaanxi Peoples R China

The effects of pore in c/Sic composites on thermal diffusivity and thermal radiation properties were investigated systematically. Pores were introduced into c/Sic by oxidizing carbon phase at 700 degrees c and damaged the thermal properties of c/Sic composites. Because of little changes in the pore shape and the pore orientation in c/Sic, thermal diffusivity of samples increased linearly with porosity. The pores within c/Sic absorbed and reflected the radiated heat, decreasing spectral emissivity. However, the temperature dependence of spectral emissivity didn't change by the pore. With measurement temperature increasing, the pores weakened the thermal radiation property of samples gradually. A linear relation was suggested to quantify the negative effect of pores on the total emissivity.

关键词： c Sic Pore Thermal diffusivity Thermal radiation

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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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comparison of ESI-MS/MS and APcI-MS methods for the quantification of folic acid analogs in c. elegans

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JOURNAL OF MASS SPEcTROMETRY 2019年第4期54卷 316-327页

作者： Annibal, Andrea Tam, Hannah Latza, christian Antebi, Adam Max Planck Inst Biol Ageing Cologne Germany Univ Cologne Cologne Excellence Cluster Cellular Stress Respon Cologne Germany

Folic acid (FA) plays a vital role in central metabolism, including the one carbon cycle, nucleotide, and amino acid biosynthesis. The development of sensitive, accurate analytical methods to measure FA intermediates in tissues is critical to understand their biological roles in diverse physiological and pathological contexts. Here, we developed a highly sensitive method for the simultaneous quantification of FA intermediates in the nematode caenorhabditis elegans as a model to dissect metabolic networks. The method was further validated by analyzing the worm folate pool upon RNAi knockdown of the dihydrofolate reductase gene dhfr-1. comparative mass spectrometry behavior of the FA analogs using two different ion sources, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APcI), revealed ESI-MS/MS to be more sensitive, but APcI-MS provided more detailed structure inferences, which can elucidate chemical investigation and synthesis of FA analogs. Finally, we report on the use of in vitro oxidation coupled with high-resolution mass spectrometry as a tool to discover new endogenous FA derivatives in the nematode.

关键词： APcI c elegans dhfr-1 ESI folic acid

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Role of serum cystatin c in the prediction of contrast-induced nephropathy after intra-arterial interventions

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chinese Medical Journal 2020年第4期133卷 408-414页

作者： Zheng-Yu Wang Yong-Li Wang Jian Wei Long Jin Zhen-chang Wang Department of Radiology Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China Department of Interventional Radiology The Sixth People's Hospital South CampusShanghai Jiao Tong UniversityShanghai 201499China

Background:The diagnosis of contrast-induced nephropathy(cIN)is usually based on changes in serum creatinine(scr).However,scr has poor sensitivity as a biomarker of kidney *** aim of this study was to investigate the usefulness of serum cystatin c(scysc)to predict cIN after intra-arterial ***:A total of 360 consecutive patients underwent intra-arterial procedures using digital subtraction ***,scysc,and estimated glomerular filtration rate were measured at 1 to 2 days before and at 48,72 h,and 7 days after the ***:Thirty-one patients(8.61%)developed *** operating characteristic(ROc)curve analysis showed that preoperative scysc levels had good discriminatory power(area under the curve[AUc]=0.634;95%confidence interval[cI]=0.526-0.743)for evaluating the risk of cIN after an endovascular procedure,with a sensitivity of 53.33%and specificity of 73.70%.ROc analysis showed that scysc at 48 h after contrast medium administration was predictive of cIN after an endovascular procedure(AUc=0.735;95%cI=0.647-0.822)with satisfactory sensitivity of 74.20%and specificity of 63.90%.Diabetes mellitus was an independent risk factor for cIN(odds ratio=2.778;95%cI=1.045-7.382;P=0.040).conclusions:Scysc is an appropriate biomarker to predict the occurrence of *** scysc before an intervention is useful to obtain a preliminary estimate of the risk of cIN.A 48-h cut-off value of scysc of 0.99 mg/L after an endovascular procedure may help to rule out patients at lower risk of cIN.

关键词： contrast-induced nephropathy Intra-arterial intervention Serum cystatin c Serum creatinine

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Acinetobacter sp. mediated synthesis of AgNPs, its optimization, characterization and synergistic antifungal activity against c. albicans

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JOURNAL OF APPLIED MIcROBIOLOGY 2019年第2期127卷 445-458页

作者： Nadhe, S. B. Singh, R. Wadhwani, S. A. chopade, B. A. Savitribai Phule Pune Univ Dept Microbiol Pune Maharashtra India SIES Coll Arts Sci & Commerce Dept Biotechnol Mumbai Maharashtra India Dr Babasaheb Ambedkar Marathwada Univ Aurangabad 431004 Maharashtra India

Aims To synthesize silver nanoparticles (AgNPs) with cell free extract of Acinetobacter sp. and evaluate antifungal activity against planktonic and biofilm of candida. Also, to study mechanism of antifungal action of AgNPs. Methods and Result Acinetobacter spp were screened for synthesis of AgNPs. Physio-chemical parameters were optimized to obtained monodispersed nanoparticles. Optimized nanoparticles were characterized using spectroscopic, microscopic and diffraction techniques. Antifungal and biofilm disruption activity of AgNPs (10 +/- 5 nm) were investigated against c. albicans. Mechanism of antifungal activity of nanosilver was deduced by growth curve, reactive oxygen species generation, thiol interaction and microscopic analysis. Acinetobacter sp. GWRFH 45 gave maximum synthesis of AgNPs. At optimized condition monodispersed, spherical nanoparticles were obtained which were crystalline with negative surface charge. AgNPs exhibited antifungal activity against planktonic cells and biofilm of candida. AgNPs showed synergistic effect with amphotericin B as well as fluconazole against biofilm disruption. AgNPs were found to affect growth of candida, generate reactive oxygen species and disrupt cellular morphology. conclusions cell free extract of A. calcoaceticus GWRFH 45 has ability to synthesize AgNPs. AgNPs alone and in combination with drugs have potential to inhibit c. albicans. Significance and Impact of the Study This is the first report of bacteriogenic AgNPs used in combination with antifungal drugs against candida.

关键词： Acinetobacter sp AgNPs antifungal biofilm c albicans disrupt morphology reactive oxygen species

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c/c++中指针编程的破解

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计算机时代 2022年第11期 121-124,129页

作者：苏杭丽李燕童端南京财经大学信息工程学院江苏南京210023

针对c/c++指针编程难的问题,提出“三步法”的解决方法。“三步法”将指针编程的整个过程归纳为固定步骤和具体任务,破解指针的抽象。在完成“三步法”的具体任务时,针对指向基本变量、一维数组、二维数组的指针,分别给出指针的定义、... 详细信息

针对c/c++指针编程难的问题,提出“三步法”的解决方法。“三步法”将指针编程的整个过程归纳为固定步骤和具体任务,破解指针的抽象。在完成“三步法”的具体任务时,针对指向基本变量、一维数组、二维数组的指针,分别给出指针的定义、初始值、表示任一元素的地址和值的固定格式,并从外形符号找出相对应的“等价”,破解指针的灵活性。最后举例说明“三步法”的使用。“三步法”在教学中取得了很好的效果。

关键词： c c++ 指针三步法

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Kinetic analysis of monomolecular cracking of normal Alkanes (c 4 c 6 ) over Brønsted Acid site of Zeolitic type catalyst with energetic evaluation of transition states using Quantum-chemical modeling

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Fuel communications 2024年 19卷

作者： Saba Foroutan Ghazvini Elena Ivashkina Nikolaevna Chemical Engineering Department Engineering School of Natural Resources National Research Tomsk Polytechnic University P.O. Box 634050 No. 30 Lenin Avenue Tomsk Russia

The work aims to determine the kinetic parameters of reactions for production of light olefins via catalytic cracking reactions of c 4 –c 6 n-alkanes based on the energy characteristics of the transition state using quantum chemical calculations. cracking reactions of c 4 –c 6 n-alkanes proceed via protolytic mechanism on the Brønsted acid sites of zeolite-containing catalysts. For kinetic studies in this work, the thermochemical parameters of the intermediate stages, including hydrocarbon adsorption and transition state were determined, then the activation energies and rate constants were determined over the temperature range of catalytic cracking process from 773 to 903 K (500–630 °c). The results showed that DFT method in combination with B3LYP and ωB97X-D functionals, and 3–21 G basis demonstrated quite high accuracy in determining thermochemical parameters, including enthalpy, entropy and Gibbs free energy at both energetic levels of adsorption and transition state. Then, modeling continued by calculations of activation energies and rate constants of reactions. Obtained kinetic parameters made it possible to determine the reactivity of hydrocarbons with different chain length. It was obtained that the rate constants of butane cracking reactions with the formation of ethylene are 54–90 times higher than the formation of propylene. The rate constants of pentane cracking reactions with the formation of butylene are on average 5 times higher than the formation of propylene. The rate constants for hexane cracking reactions with the formation of butylene are 2.9–3.7 times higher compared to the formation of propylene.

关键词： Light olefins c 4- c 6 Kinetics Transition state Quantum calculations

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Effects of spring fire and slope on the aboveground biomass, and organic c and N dynamics in a semi-arid grassland of northern china

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Journal of Arid Land 2019年第2期11卷 267-279页

作者： ZHAO Xiang HU Shuya DONG Jie REN Min ZHANG Xiaolin DONG Kuanhu WANG changhui College of Animal Science and Veterinary Medicine Shanxi Agricultural University State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing Institute of Science and Technology Information

The aboveground primary production is a major source of carbon(c) and nitrogen(N) pool and plays an important role in regulating the response of ecosystem and nutrient cycling to natural and anthropogenic disturbances. To explore the mechanisms underlying the effect of spring fire and topography on the aboveground biomass(AGB) and the soil c and N pool, we conducted a field experiment between April 2014 and August 2016 in a semi-arid grassland of northern china to examine the effects of slope and spring fire, and their potential interactions on the AGB and organic c and total N contents in different plant functional groups(c_3 grasses, c_4 grasses, forbs, Artemisia frigida plants, total grasses and total plants).The dynamics of AGB and the contents of organic c and N in the plants were examined in the burned and unburned plots on different slope positions(upper and lower). There were differences in the total AGB of all plants between the two slope positions. The AGB of grasses was higher on the lower slope than on the upper slope in July. On the lower slope, spring fire marginally or significantly increased the AGB of c_3 grasses, forbs, total grasses and total plants in June and August, but decreased the AGB of c_4 grasses and *** plants from June to August. On the upper slope, however, spring fire significantly increased the AGB of forbs in June, the AGB of c_3 grasses and total grasses in July, and the AGB of forbs and c_4 grasses in August. Spring fire exhibited no significant effect on the total AGB of all plants on the lower and upper slopes in 2014 and 2015. In 2016, the total AGB in the burned plots showed a decreasing trend after fire burning compared with the unburned plots. The different plant functional groups had different responses to slope positions in terms of organic c and N contents in the plants. The lower and upper slopes differed with respect to the organic c and N contents of c_3 grasses, c_4 grasses, total grasses, forbs, A. frigida plan

关键词： aboveground biomass plant functional group spring fire slope position N content organic c content semi-arid grassland

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