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Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

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Chinese Chemical Letters 2009年第2期20卷 213-216页

作者： Zhi Mei liu Xiao huan Zang wei hua liu Chun Wang Zhi Wang Key Laboratory of Bioinorganic Chemistry College of Sciences Agricultural University of Hebei Baoding 071001 China

A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs）（S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

关键词： Carbamate pesticides High performance liquid chromatography Diode array detection Dispersive liquid-liquid microextraction Water samples

Zinc finger protein rotund deficiency affects development of the thoracic leg in Bombyx mori

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Insect Science 2017年第3期24卷 385-396页

作者： Chun-Yan Zhou Xing-Fu Zha hua-wei liu Qing-You Xia State Key Laboratory of Silkworm Genome Biology College of Biotechnology Southwest University Chongqing China

The insect limb develops from the imaginal disc or larval leg during metamor- phosis. The molecular mechanisms involved in the development from the larval to the adult leg are poorly understood. Herein, we cloned the full length of a zinc finger gene rotund from Bombyx mori （Bmrn）, which contained a 1419 bp open reading frame, and encoded a 473 amino acid protein. Reverse transcription polymerase chain reaction and Western blot analyses demonstrated that Bmrn was expressed at higher levels in the epidermis than in other tissues tested, and it showed a very high expression level during metamorphosis. Knock-down of Bmrn produced defects in the tarsus and pretarsus, including the fusion and reduction of tarsomeres, and the developmental arrest of pretarsus. Our data showed that Bmrn is involved in the formation of the tarsus and pretarsus, whereas its homologous gene in Drosophila has been shown to affect three tarsal segments （t2-t4）, suggesting that the remodeling of the leg has involved changes in the patterning of gene regulation during evolution.

关键词： Bombyx mori limb / leg development pretarsus RNAi rotund/rn tarsus

Modification of inorganic binder used for sand core-making in foundry practice

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China Foundry 2020年第5期17卷 341-346页

作者： Fang-hai Xin wei-hua liu Lai Song Ying-min Li Shenyang University of Technology Shenyang 110870China

With modified water glass as binder and the introduction of micro silicon powders into the coremaking process,an improvement was made to the tensile strength and collapsibility of the sand *** potassium hydroxide,sodium hexametaphosphate and white sugar were applied as the modifiers of water *** optimum proportion of the modifiers was determined through the combination of single factor test and orthogonal *** optimum proportion of water glass,potassium hydroxide,sodium hexametaphosphate and white sugar is 1000:40:5:5(wt.).In terms of weight,modified binder and micro silicon powders accounted for 2%and 0.6%of sand,*** sand core was hardened by going through a warm core box process,in which the temperature of core box was 150°C,and the compressed hot air was blown at 120°C for 40 s under a pressure of 0.2 *** for the sand core bonded with modified water glass,the tensile strength is 2.46 MPa at room temperature(σ0)and 2.49 MPa at 25°C and 40%RH for 24 h(σ24),which are 2 times more than that with unmodified *** bonded strengths of sand core are increased as a result of the reaction between-OH groups from addition of potassium hydroxide and SiO2 particles widely distributed in the sand *** with the sand core bonded with unmodified water glass,the high temperature residual tensile strength(σr)of sand core bonded with modified water glass under 600°C for 5 min,is sharply reduced from 0.20 MPa to 0.01 *** the comparison with unmodified water glass,the dynamic viscosity of the modified water glass and the flowability of molding sand using modified water glass are increased from 74 mPa·s and 2.15 g to 80 mPa·s and 2.21 g,*** revealed by FT-IR analysis,new groups including PO3-,PO43-,and Si-O-C appear in the molecular structure of modified water glass,which are beneficial to the collapsibility of sand core.

关键词： inorganic binder modified water glass tensile strength collapsibility warm box core-making process

Protease inhibitors in Bombyx mori silk might participate in protecting the pupating larva from microbial infection

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Insect Science 2016年第6期23卷 835-842页

作者： You-Shan Li hua-wei liu Rui Zhu Qing-You Xia Ping Zhao State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing Vitamin D Research Institute Shaanxi University of Technology Hanzhong Shaanxi Province School of Management Shaanxi University of Technology Hanzhong Shaanxi Province China

Pupae inside cocoons rarely suffer from disease. It is apparent that some factors in the cocoon exert antimicrobial effects whereby the pupae inside can be protected from microbial infection. In the present study, we investigated the expression of cocoon protease inhibitors using immunoblotting and activity staining. Enzymatic hydrolysis of cocoon proteins in vitro was performed to characterize their roles in protecting the cocoon from microbial proteases. We found that some protease inhibitors, particularly trypsin inhibitor-like （TIL）-type protease inhibitors, can be secreted into the cocoon layer during the spinning process, thereby providing effective protection to the cocoon and pupa by inhibiting the extracellular proteases that can be secreted by pathogens.

关键词： Bombyx mori cocoon enzymatic hydrolysis microbial proteases protease inhibitors pupating larva

Free-radical evolution and decay in cross-linked polytetrafluoroethylene irradiated by gamma-rays

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Nuclear Science and Techniques 2022年第5期33卷 113-125页

作者： Fei-Xiang Sha Guo-Jun Cheng Zi-Yue Xuan Yang liu wei-hua liu Xiao-Dong Zhang Zhong-Feng Tang School of Materials Science and Engineering Anhui University of Science and TechnologyHuainan 232000China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environment Harbin Institute of TechnologyHarbin 150001China University of Chinese Academy of Sciences Beijing 100049China

Electron spin resonance techniques were employed to investigate the effects of the absorbed dose and post-irradiation conditions on the evolution and decay of free-radicals in cross-linked polytetrafluoroethylene(XPTFE),induced byγ-ray ***-end free-radicals,chain alkyl free-radicals,and tertiary alkyl free-radicals were detected when XPTFE was irradiated under Ar *** corresponding peroxy free-radicals were formed upon exposure of irradiated XPTFE to air;the freeradicals concentration first increased linearly with increasing absorbed dose and then gradually *** free-radicals yield under air atmosphere was greater than that under Ar,and the peroxy free-radicals were preserved for a relatively long time when irradiated XPTFE was stored under air *** chain alkyl free-radicals may be converted to chain end free-radicals byβ-scission,while chain end free-radicals are more sensitive to oxygen than chain alkyl *** the annealing temperature was raised above the a-transition temperature of XPTFE,the decay of the free-radicals was greatly affected and accelerated by the motion of the molecules over the long range.

关键词： Polytetrafluoroethylene Cross-linked polytetrafluoroethylene Electron spinresonance Decay Radiation c-ray

Humidity-resistant inorganic binder for sand core making in foundry practice

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China Foundry 2019年第4期16卷 267-271页

作者： Lai Song wei-hua liu Ying-min Li Fang-hai Xin Shenyang University of Technology

The performance of sand core was improved by using the modified water glass as a binder and adding powder additives in the sand hardening process. The optimal proportion of the compound additives was determined by an orthogonal test, with a ratio of microsilica: polyvinyl alcohol solution: borax: B agent = 25: 20: 2: 1. The binder accounted for 2% of the sand by weight, and the compound additives accounted for 0.96%. The core box was heated to 175 °C, and the compressed hot air of 120 °C kept blowing for 40 s. Tensile strength was used as the main indicator to evaluate the humidity-resistance of the sand core. For the sand core, the instant tensile strength reached 0.73 MPa, the tensile strength at room temperature was 1.81 MPa, and that of sand core holding at the condition of 35 °C and 90% RH for 2 h and for 4 h reached 1.61 MPa and 1.19 MPa, respectively. The gas evolution was 7.5 mL·g-1 at 850 °C for 3 min. The residual tensile strength was 0 MPa at 750 °C for 5 min. Fourier-transform infrared spectroscopy analysis showed that the humidity-resistance of the core was greatly improved by the powder additives.

关键词： water glass inorganic binder compound additives humidity-resistance

Preparation of a new animal glue binder for foundry use

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China Foundry 2016年第4期13卷 238-242页

作者： wei-hua liu Tian-shu Wang Ying-min Li Yu-yan Ren Wen-hui Huo School of Materials Science and Engineering Shenyang University of Technology

A new casting binder was prepared based on an animal bone glue. In order to overcome the disadvantages of the animal glue agglomeration at room temperature, an alkaline decomposition process was used, with acrylic acid, ammonium persulfate, and glucose as modifiers of the animal glue to obtain a high strength of binding. In the process of alkaline decomposition, Na OH was used as the catalyst with the addition of 3, 4, 5, 6, 7, 8wt.%, respectively, into 100 g of animal glue and the alkaline decomposition temperature was set for 30, 40, 50, 60, and 70 °C, with an identical decomposition time of 30 min, in order to reduce viscosity of the animal glue and maintain a liquid state at room temperature. The added acrylic acid, ammonium persulfate and glucose were determined through an orthogonal experiment. The experimental results are as fol ows: the optimal amount of NaOH addition is 5wt.%; alkaline decomposition temperature is 50 °C; the optimal weight ratio of three kinds of modifiers to animal glue is acrylic acid : ammonium persulfate : glucose : animal glue = 30:3:15:100; the modification reaction should be performed at 75 °C with a reaction time of 90 min. With the addition of 3% binder to sand, a final tensile strength of about 3.36 MPa and surface tension value of about 25.387 m N·m^(-1) are achieved; the gas evolution at 850 °C is 19 ml·g^(-1) and the residual strength after high temperature(700 ■× 10 min) is 0 MPa. Finally, the new binder was characterized and analyzed by means of element analysis and an IR infrared spectrum.

关键词： animal glue alkaline decomposition modification graft copolymerization etherification cross-linking

Oxidative cyclization of allyl compounds and isocyanide: A facile entry to polysubstituted 2-cyanopyrroles

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Chinese Chemical Letters 2024年第4期35卷 330-335页

作者： Yaping Zhang wei Zhou Mingchun Gao Tianqi liu Bingxin liu Chang-hua Ding Bin Xu Department of Chemistry Affiliated Nantong Hospital of Shanghai University(The Sixth People's Hospital of Nantong)Shanghai Engineering Research Center of Organ RepairInnovative Drug Research CenterSchool of MedicineShanghai UniversityShanghai 200444China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

A facile Tf OH-catalyzed oxidative cyclization of allyl compounds and isocyanide has been developed with the assistance of DDQ, where isocyanide is used as the crucial "N" and "CN" sources. Highly functionalized 2-cyanopyrroles are constructed efficiently through a new formal [3 + 2] mode, demonstrating diverse reactivity and synthetic utility in organic chemistry. 2-Cyanopyrrole is converted into a nucleobase analogue of Remdesivir and 5H-pyrrolo[2,1-a]isoindole through a three-step or a two-step sequence, respectively. This protocol features broad substrate scope, operational simplicity and good functional group tolerance.

关键词： Isocyanide Cyanopyrrole Insertion Allyl compound Bronsted acid catalysis

Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

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Petroleum Science 2024年第2期21卷 1275-1289页

作者： Qian Li Zi-Jie Lin liu Yang Yue Wang Yue Li wei-hua Cai Laboratory of Thermo-Fluid Science and Nuclear Engineering Northeast Electric Power UniversityJilin132000JilinChina School of Energy and Power Engineering Northeast Electric Power UniversityJilin132000JilinChina

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 *** simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow *** results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were *** calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So hea

关键词： Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis