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Chinese Chemical Letters 2014年第4期25卷 635-639页

作者： Jian-Xiang Huang Da-Hai Lu Kai Wan Fu-Hua Wang Public Monitoring Center for Agro-product Guangdong Academy of Agricultural Sciences

In this study, a method based on low temperature purification （LTP） coupled with liquid chromatography-tandem mass spectrometry （LC-MS/MS） was developed for the determination of abamectin （ABA） and ivermectin （IVR） in edible oils. ABA and IVR were extracted using conventional liquid-liquid extraction followed by purification via precipitation of interfering fatty components at low temperature without an additional cleanup step. LTP is simple, easy to use, labour-saving and cost effective, and requires reduced amounts of organic solvent. The linear ranges of ABA and IVR were 5- 1000 t^g/L using matrix-matched standards. Limits of detection （LOD） and limits of quantification （LOQ） were in the range of 0.1-0.4 i^g/kg and 0.3-1.3 p^g/kg, respectively. The LOQs were below the strictest maximum residue limits established by Codex Alimentarius Commission. Recoveries at three spiked levels of 10, 20 and 100 i^g/kg in peanut oil, corn oil, olive oil, soybean oil and lard ranged from 71.1% to 119.3% with relative standard deviations of 3.2%-10.3%, which were in agreement with those obtained by the solid phase extraction method. The proposed method was utilized in the analysis of 10 edible oil samples from local market and neither ABA nor IVR was detected. As far as we know, this is the first time that LTP is applied to the determination of avermectins in edible oils.

关键词： Low temperature purification Abamectin Ivermectin Edible oil Liquid chromatography-tandem massspectrometry

Identification and characterization of Pichia membranifaciens Hmp-1 isolated from spoilage blackberry wine

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Journal of Integrative Agriculture 2018年第9期17卷 2126-2136页

作者： WANG Ying ZHAO Yan-cun FAN Lin-lin XIA Xiu-dong LI Ya-hui ZHOU Jian-zhong Institute of Agro-product Processing Jiangsu Academy of Agricultural Sciences Institute of Plant Protection Jiangsu Academy of Agricultural Sciences

The pellicle-forming yeast could cause the quality deterioration of wine. In this study, a pellicle-forming strain Hmp-1 was isolated from the spoilage blackberry wine, and identified as Pichia membranifaciens based on the morphology and partial nucleotide sequence of 26S rDNA. The effects of fermentation conditions （ethanol, sulfur dioxide, sugar, and temperature） on the growth of P. membranifaciens strain Hmp-1 and Saccharomyces cerevisiae strain FM^S-115 （a strain used for the blackberry wine fermentation） were investigated, respectively. The results indicated that Hmp-1 had lower resistance to these factors compared to FM-S-115, and the growth of Hmp-1 was completely inhibited by 10% （v/v） or 50 mg L-~ SO2 during the fermentation of blackberry wine. These results suggested that Hmp-1 could effectively be controlled by increasing ethanol or SO2 concentration during the fermentation and storage of blackberry wine. Furthermore, the analysis based on gas chromatography-mass spectrometry （GC-MS） showed that Hmp-1 remarkably decreased kinds of volatile compounds in blackberry wine, especially aldehydes and esters. In addition, some poisonous compounds were detected in the blackberry wine fermented by FM-S-115 and Hmp-l. These results suggested that Hmp-1 was a major cause leading to the quality deterioration of blackberry wine.

关键词： Picihia membranifaciens Hmp-1 blackberry wine pellicle-forming spoilage population dynamics volatile compounds

Structure and Properties of Self-assembled Narural Rubber/Multi-walled Carbon Nanotube Composites

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Journal of Wuhan University of Technology(Materials Science) 2011年第5期26卷 807-811页

作者：彭政罗勇悦 Chinese Agricultural Ministry Key Laboratory of Tropical Crop product Processing Agricultural Product Processing Research InstituteChinese Academy of Tropical Agricultural Sciences

Natural rubber （NR）/multi-walled carbon nanotube （MWCNTs） composites were prepared by combining self-assembly and latex compounding *** acid-treated MWCNTs （H2SO4：HNO3=3：1,volume ratio） were self-assembled with poly （diallyldimethylammonium chloride）（PDDA） through electrostatic *** the second assembling,NR/MWCNTs composites were developed by mixing MWCNTs/PDDA solution with NR *** results show that MWCNTs are homogenously distributed throughout the NR matrix as single tube and present a great interfacial adhesion with NR phase when MWCNTs contents are less than 3 wt%.Moreover,the addition of the MWCNTs brings about the remarkable enhancement in tensile strength and crosslink density compared with the NR host,and the data peak at 2 wt% MWCNTs *** more MWCNTs are loaded,aggregations of MWCNTs are gradually generated,and the tensile strength and crosslink both decrease to a certain extent.

关键词： natural rubber (NR) multi-walled carbon nanotube (MWCNTs) composites latex compounding self-assembly

Derivation of soil Pb/Cd/As thresholds for safety of vegetable planting: A case study for pakchoi in Guangdong Province,China

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Journal of Integrative Agriculture 2019年第1期18卷 179-189页

作者： LI Fu-rong WEN Dian WANG Fu-hua SUN Fang-fang WANG Xu DU Ying-qiong LIU Xiang-xiang WAN Kai Public Monitoring Center for Agro-product of Guangdong Academy of Agricultural sciences/Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality Ministry of Agriculture/Laboratory of Quality & Safety Risk Assessment for Agro-product (Guangzhou)Ministry of Agriculture

Regional guidelines for soil heavy metals,in conjunction with specific crops,are proposed to better assess soil environmental *** this study,large amounts of soils with different levels of Pb/Cd/As pollution were collected in Guangdong Province,China,to carry out a pot experiment,which was closer to the actual situation and properties of the heavy metal contaminated *** the widely planted vegetable pakchoi as the research object,we analyzed the correlations between the Pb/Cd/As concentrations in pakchoi and the total or available soil Pb/Cd/As concentrations and established their optimal regression *** then,the total and available soil Pb/Cd/As thresholds for pakchoi were calculated according to the allowable Pb/Cd/As limits in pakchoi and were compared with the current soil assessment ***,a lot of paired vegetable-soil samples in field were collected and their pollution situations were assessed by both the current limit thresholds and the calculated ***,it was more consistent to assess the Cd and As pollution situation of the vegetable and soil samples with the calculated soil thresholds than the current soil assessment *** further proved that it was necessary to explore the soil heavy metal thresholds for safety of vegetable in specific regions,which would be more scientific and practical to guide safety production of local agricultural products and effective utilization of soil resources.

关键词： heavy metal pollution available content soil threshold correlation analysis vegetable

Thermal degradation of epoxidized natural rubber in presence of neodymium stearate

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Journal of Rare Earths 2013年第5期31卷 526-530页

作者：罗勇悦杨昌金陈帮乾许逵钟杰平彭政吕臻王庆煌 Chinese Agricultural Ministry Key Laboratory of Tropical Crop product Processing Agricultural Product Processing Research InstituteChinese Academy of Tropical Agricultural Sciences Rubber Research Institute Chinese Academy of Tropical Agricultural Sciences School of Science Guangdong Ocean University

The effect of neodymium stearate （NdSt） synthesized by saponification method on thermal degradation and thermo-oxidative degradation of expoxidized natural rubber with 25 mol.% epoxidation （ENR25） was investigated by thermogravimetric analysis （TGA）, and the structure of ENR25 vulcanized with NdSt after thermo-oxidative decomposition was characterized using Fourier transform infared spectroscopy-attenuated total-reflectance （FTIR-ATR）. The thermal degradation kinetic parameters of ENR25 with different loadings of NdSt were determined by Coats-Redfern method. The results showed that the thermal degradation of ENR25 in nitrogen was a one-step reaction regardless of NdSt content, whereas the thermo-oxidative degradation was a multiple-step reaction. The thermal and thermo-oxidative stability of the ENR25 vulcanizates with the addition of NdSt was higher than that of pure ENR25 vulcanizates. The ENR25 vulcanizates with the incorporation of 1 phr （per hundred parts of rubber） NdSt imparted the highest activa- tion energy （E） of thermal and thermo-oxidative degradation. This could be attributed to the many unoccupied orbits in rare earth Nd, which could capture the free radicals and make the epoxide groups stable in the process of thermal and thermo-oxidative degradation for ENR25.

关键词： neodymium stearate ENR25 thermal degradation thermo-oxidative degradation kinetic rare earths 1

Comparison effects of lanthanum stearate and antioxidants in epoxidized natural rubber

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Journal of Rare Earths 2015年第11期33卷 1236-1240页

作者：杨昌金罗勇悦彭政许逵钟杰平 Chinese Agricultural Ministry Key Laboratory of Tropical Crop product Processing Agricultural Product Processing Research Institute Chinese Academy of Tropical Agricultural Sciences Rubber Research Institute Chinese Academy of Tropical Agricultural Sciences School of Science Guangdong Ocean University

This work studied possibilities of using lanthanum stearate（LaS t） as an antioxidant in epoxidized natural rubber containing 25 mol.% expoxidation（ENR25） compounds. For comparison purposes, two commercial antioxidant 4010 NA and MB were also used. The influence of LaS t, antioxidant 4010 NA and MB on cure characteristics, mechanical properties, crosslink density, hot air aging and thermo-oxidative degradation were studied. The results indicated that the incorporation of LaS t and antioxidants could accelerate the vulcanization of ENR. The ENR vulcanizates with antioxidant MB had better mechanical properties than 4010 NA and LaS t. Compared with antioxidant 4010 NA and MB, the ENR25 vulcanizates with the addition of LaS t exhibited the best hot air aging resistance and thermo-oxidative stability.

关键词： lanthanum stearate antioxidants ENR25 thermal degradation hot air aging resistance rare earths

Asymmetric synthesis of difluorinated α-quaternary amino acids (DFAAs) via Cu-catalyzed difluorobenzylation of aldimine esters

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Chinese Chemical Letters 2024年第12期35卷 444-449页

作者： Xiang Huang Dongzhen Xu Yang Liu Xia Huang Yangfan Wu Dongmei Fang Bing Xia Wei Jiao Jian Liao Min Wang Chengdu Institute of Organic Chemistry Chinese Academy of Sciences University of Chinese Academy of sciences Natural product Research Center Chengdu Institute of BiologyChinese Academy of Sciences

Increasing interests of difluorinated amino acids (DFAAs) have been raised in recent years due to their widespread bio-organic and medical ***,to date,only few investigations focused on their asymmetric *** difluoromethyl reagent to tailor a novel pathway and developing efficient catalytic system are highly desirable for constructing structurally diverse chiral ***,a copper-catalyzed asymmetric difluorobenzylation of aldimine esters is *** using α,α-difluorinated benzyltriflones as difluoromethyl reagents,this protocol allows the asymmetric synthesis ofα-quaternary DFAAs with wide scope,good yields and excellent enantioselectivities (90%-98%ee).Control experiments and DESI-MS analysis demonstrate the reaction probably proceeds via a key difluorocarbocation ***,polyfluoroarenes are found efficient candidates to polyfluoroaryl amino acids via C-F ***-scale experiment,late-stage functionalization,synthesis of difluorinated dipeptides and bioactive molecular analogues revealed the utility of the protocol,thereby largely enriching the structural diversity of FAAs and providing more potential opportunities in drug discovery.

关键词： Cu-catalyzed Asymmetric difluorobenzylation Polyfluoroaryl amino acids Difluorocarbocation

Effects of different drying methods on quality,bacterial viability and storage stability of probiotic enriched apple snacks

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Journal of Integrative Agriculture 2018年第1期17卷 247-255页

作者： CUI Li NIU Li-ying LI Da-jing LIU Chun-quan LIU Ying-ping LIU Chun-ju SONG Jiang-feng Institute of Farm product Processing Jiangsu Academy of Agricultural Sciences College of Food Science and Engineering Yangzhou University

Effects of four different drying methods on the colour, texture, sensory quality, microstructure, bacterial viability and storage stability of probiotic-enriched apple snacks were assessed. The drying methods were air drying （AD）, freeze drying （FD）, freeze drying followed by microwave vacuum drying （FD＋MVD） and air drying followed by explosion puffing drying （AD＋EPD）. Overall, FD＋MVD can be used as a suitable drying method for the development of probiotic enriched apple snacks in consideration of colour, texture, sensory quality, bacterial viability and storage stability. Probiotic bacteria in FD＋MVD-dried samples remained above 1×106 CFU g 1 for 120 days at 25℃C. Interestingly, bacterial viability in FD＋MVD-dried samples turned out to be significantly higher than FD-dried samples during storage for 120 days.

关键词： drying apple snacks probiotic viability microwave vacuum

Enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via β-elimination/cycloaddition sequence

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Chinese Chemical Letters 2018年第8期29卷 1215-1218页

作者： Lu Xue Yidong Liu Wenling Qin Hailong Yan Chongqing Key Laboratory of Natural product Synthesis and Drug Research School of Pharmaceutical Sciences Chongqing University

A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities（85%-98% ee and 84%-95% ee）.

关键词： One-pot synthesis Enantioselective β-eliminationd Asymmetric cycloaddition Chiral sulfones Trisubstituted tetrahydrothiophenes Ion-pairing catalysis

Two natural molecules preferentially inhibit azole-resistant Candida albicans with MDR1 hyperactivation

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Chinese Journal of Natural Medicines 2019年第3期17卷 209-217页

作者： SHI Hong-Zhuo CHANG Wen-Qiang ZHANG Ming LOU Hong-Xiang Department of Natural product Chemistry Key Laboratory of Chemical Biology of Ministry of Education School of Pharmaceutical Sciences Shandong University

Antifungal drug resistance is a significant clinical problem, and antifungal agents that can evade resistance are urgently needed. In infective niches, resistant organisms often co-existed with sensitive ones, or a subpopulation of antibiotic-susceptible organisms may evolve into resistant ones during antibiotic treatment and eventually dominate the whole population. In this study, we established a co-culture assay in which an azole-resistant Candida albicans strain was mixed with a susceptible strain labeled with green fluorescent protein to mimic in vivo conditions and screen for antifungal drugs. Fluconazole was used as a positive control to verify the validity of this co-culture assay. Five natural molecules exhibited antifungal activity against both susceptible and resistant C. albicans. Two of these compounds, retigeric acid B(RAB) and riccardin D(RD), preferentially inhibited C. albicans strains in which the efflux pump MDR1 was activated. This selectivity was attributed to greater intracellular accumulation of the drugs in the resistant strains. Changes in sterol and lipid compositions were observed in the resistant strains compared to the susceptible strain, and might increase cell permeability to RAB and RD. In addition, RAB and RD interfered with the sterol pathway, further aggregating the decrease in ergosterol in the sterol synthesis pathway in the MDR1-activated strains. Our findings here provide an alternative for combating resistant pathogenic fungi.

关键词： Candida albicans MDR1 Azole resistance Co-culture