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蔬菜蚜虫抗药性现状及治理策略 预览
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作者 苗艳香 《热带农业工程》 2019年第1期68-70,共3页
蚜虫是影响蔬菜作物生长的一种害虫,蚜虫灾害给农民带来了巨大的经济损失。目前,对蚜虫灾害防治主要依靠农药,长期以来由于人们不合理使用农药和对农作物生长习性了解不足,致使蔬菜蚜虫对较多种类的杀虫剂产生了抗药性。对常见蔬菜植物... 蚜虫是影响蔬菜作物生长的一种害虫,蚜虫灾害给农民带来了巨大的经济损失。目前,对蚜虫灾害防治主要依靠农药,长期以来由于人们不合理使用农药和对农作物生长习性了解不足,致使蔬菜蚜虫对较多种类的杀虫剂产生了抗药性。对常见蔬菜植物蚜虫的抗药性进行了详细综述,并提出了一些切实可行的防治策略,希望为今后蔬菜蚜虫防治提供技术参考。 展开更多
关键词 蔬菜蚜虫 抗药性 抗药性机制 抗药性治理
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Effects of Seaweed Extracts on Promoting Growth and Improving Stress Resistance in Sugarcane 预览
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作者 Diwen CHEN Ying HUANG +6 位作者 Dachun SHEN Wenling ZHOU Junhua AO Yong JIANG Zhenrui HUANG Hassan Munir Fahd Rasul 《亚洲农业研究:英文版》 2019年第4期69-72,76共5页
A field investigation was executed in sugarcane producing area of Zhanjiang,Guangdong Province with YT03-373 as the test variety to understand the possible impacts of seaweed extracts on phenology,yield and quality at... A field investigation was executed in sugarcane producing area of Zhanjiang,Guangdong Province with YT03-373 as the test variety to understand the possible impacts of seaweed extracts on phenology,yield and quality attributes of sugarcane. Foliar application of seaweed extracts were carried out on sugarcane at seedling and tillering stages. Agronomic traits,yield,sugar content,leaf drought resistance and pest resistance of sugarcane were analyzed for optimization of application time at proper phenological stages. The results that compared to the control,the application of seaweed extracts at different stages of sugarcane enhanced production of sugarcane with increase rate of 10. 83%-12. 87%,and improved theoretical sugar yield of sugarcane up to 1. 9 t/ha while enhancing water retention capacity and water content of sugarcane leaves that consequently led to wilting risk reduction by escaping drought and improved resilience to drought impact on sugarcane. Seaweed extracts also performed excellent in pest management of sugarcane,and they exerted different control effects on sugarcane borers,aphids and thrips. An increase in output of sugarcane was observed to be 15. 09% compared to control,while the net income was improved by up to 32. 64% in the seaweed extracts application treatment. Foliar application of seaweed extracts not only enhanced growth,cold resistance,pest resistance,output value but also improved economic returns,giving a positive affirmation for the recommendation of seaweed extract application. 展开更多
关键词 SEAWEED extracts FOLIAR application SUGAR recovery DROUGHT RESISTANCE Pest RESISTANCE
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Manufacture and characteristics of Al2O3 composite coating on steel substrate by SHS process
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作者 Hai-Dong Gao Ze-Hua Wang Jia Shao 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第7期704-712,共9页
Many steel components are needed to be reinforced on their surface to have a high abrasive resistance and corrosion resistance. Based on self-propagating hightemperature synthesis, a process to making Al2O3 composite ... Many steel components are needed to be reinforced on their surface to have a high abrasive resistance and corrosion resistance. Based on self-propagating hightemperature synthesis, a process to making Al2O3 composite coatings on mild steel substrate in atmospheric environment with the help of simple auxiliary facilities was developed successfully. A pre-coated bilayer coating was employed. The effects of Fe content in pre-coated transition layer on phase composition, porosity and interfacial bon ding were studied using scanning electron microscopy (SEM), energy-dispersive spectrum (EDS) and X-ray diffraction (XRD). The thermal shock resistance and abrasive resistance were investigated. When Fe content changes from 0 wt% to 50 wt%, the bond quality at first becomes better and then worse gradually. When Fe content is less 20 wt%, there is a small gap between the transition layer and the substrate;when Fe contents are 30 wt% and 40 wt%, working layer, the transition layer and the substrate bond together well. The working layer is mainly composed of Al2O3, Fe-Cr and Al(Cr)2O3 phases and has a dense structure with porosity of less than 1 %. The coating has a good thermal shock resistance and abrasive resistance. The abrasive resistance of the working layer is about ten times that of the substrate. 展开更多
关键词 AL2O3 composite coating Self-propagating high-temperature synthesis INTERFACIAL BONDING Thermal shock RESISTANCE ABRASIVE RESISTANCE
大肠埃希菌耐药机制研究进展 预览
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作者 王帅杨 李崇 +2 位作者 张建武 赖重波 司红彬 《动物医学进展》 北大核心 2019年第8期92-97,共6页
大肠埃希菌在自然界中广泛存在,在一定的条件下可以引起畜禽患病,在长期治疗过程中,由于药物的选择压力可以引起其对药物的抗性,而且耐药广泛、耐药机制复杂,给疾病临床治疗带来了一定的困难。大肠埃希菌耐药机制主要包括细胞膜通透性... 大肠埃希菌在自然界中广泛存在,在一定的条件下可以引起畜禽患病,在长期治疗过程中,由于药物的选择压力可以引起其对药物的抗性,而且耐药广泛、耐药机制复杂,给疾病临床治疗带来了一定的困难。大肠埃希菌耐药机制主要包括细胞膜通透性改变、细菌产生灭活酶或者钝化酶、靶点结构改变、主动外排泵、质粒介导的大肠埃希菌耐药等。论文介绍了我国部分地区畜牧业中大肠埃希菌耐药现状、大肠埃希菌耐药机制以及应对大肠埃希菌耐药的策略,以便了解耐药大肠埃希菌的传播特点,为防治大肠埃希菌耐药性产生和临床治疗大肠埃希菌感染提供一定的理论指导。 展开更多
关键词 大肠埃希菌 耐药性 耐药机制 抗菌药
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Urban recreational water – potential breeding ground for antibiotic resistant bacteria?
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作者 Jing Yang Xu Connie Le +1 位作者 Baowei Chen Hongquan Zhang 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第7期1-3,共3页
The emergence of multidrug-resistant bacteria, or'superbugs,' has become an urgent and worldwide concern.Antibiotic-resistant bacteria (ARB) cause significant morbidity and mortality (O’Neill, 2016). It has b... The emergence of multidrug-resistant bacteria, or'superbugs,' has become an urgent and worldwide concern.Antibiotic-resistant bacteria (ARB) cause significant morbidity and mortality (O’Neill, 2016). It has been estimated that ARB cause at least 23,000 deaths annually in the United States alone and hundreds of thousands of deaths in developing countries (Bougnom and Piddock, 2017). 展开更多
关键词 Antibiotic RESISTANCE genes (ARGs) MULTIDRUG RESISTANCE in bacteria MICROBIAL PATHOGENS LAKE water and sediment
Detection of Resistance and Cross-resistance to Four ALS-inhibiting Herbicides of Scirpus juncoides Roxb.in Paddy Field in Heilongjiang Province 预览
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作者 Liu Ya-guang Zhang Zheng-nan +2 位作者 Shi Hui Zhu Jin-wen Wu Hui-peng 《东北农业大学学报:英文版》 CAS 2019年第2期1-14,共14页
The resistance and cross-resistance of Scirpus juncoides Roxb.to ALS-inhibiting herbicides were tested to provide theoretical basis for effectively control Scirpus juncoides Roxb.and rational use of herbicides.To iden... The resistance and cross-resistance of Scirpus juncoides Roxb.to ALS-inhibiting herbicides were tested to provide theoretical basis for effectively control Scirpus juncoides Roxb.and rational use of herbicides.To identify the resistance and crossresistance of 19 populations from nine areas in Heilongjiang Province to four ALS-inhibiting herbicides by agar method and the whole-plant assay.The results are as the followings,the two bioassay methods had good correlation,the resistance indexes in the same area were different by two means,but resistant level was the same,similarity up to 89.5%.The resistant rates to pyrazosulfuronethyl,bensulfuron-methyl,penoxsulam and pyribenzoxim were 26.3%,36.8%,36.1%and 21.1%,respectively.Shangzhi populations evolved the highest level of resistance to pyrazosulfuron-methyl with a resistance index of 15.56.Shangzhi,Tonghe,Fangzheng and Jixi populations showed cross-resistance to four ALS-inhibiting herbicides,accounting for 26.3%.The resistance of Scirpus juncoides Roxb.to four ALS-inhibiting herbicides in Heilongjiang paddy field was low to moderate,five populations showed cross-resistance to four ALS-inhibiting herbicides. 展开更多
关键词 SCIRPUS juncoides Roxb. ALS-inhibiting HERBICIDE RESISTANCE CROSS-RESISTANCE
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宠物犬源沙门氏菌和葡萄球菌耐药性及耐药基因检测 预览 被引量:1
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作者 轩慧勇 林亚军 +2 位作者 高超 吾买尔江·牙合甫 夏利宁 《西北农林科技大学学报:自然科学版》 CSCD 北大核心 2019年第3期14-20,共7页
【目的】了解新疆乌鲁木齐市宠物犬源沙门氏菌和葡萄球菌的耐药性及耐药基因携带情况。【方法】从77份宠物犬直肠粪便样品中分离沙门氏菌和葡萄球菌,采用琼脂稀释法对分离的菌株进行药敏试验,通过PCR方法对沙门氏菌6类23种耐药基因和葡... 【目的】了解新疆乌鲁木齐市宠物犬源沙门氏菌和葡萄球菌的耐药性及耐药基因携带情况。【方法】从77份宠物犬直肠粪便样品中分离沙门氏菌和葡萄球菌,采用琼脂稀释法对分离的菌株进行药敏试验,通过PCR方法对沙门氏菌6类23种耐药基因和葡萄球菌5类9种耐药基因进行检测。【结果】从77份宠物犬粪便样品中分离到沙门氏菌36株,葡萄球菌75株。除头孢噻呋、安普霉素、阿米卡星、硫酸庆大霉素和多黏菌素外,宠物犬源沙门氏菌对其他被捡抗菌药物的耐药率高达97.0%以上,多重耐药以8耐为主,tetB、blaTEM、blaOXA、qnrS、oqxA、oqxB、aac(6′)-Ib-cr、ant(3″)-Ia和floR基因检出率在97.0%以上。宠物犬源葡萄球菌对左氧氟沙星(93.5%)、苯唑西林(90.7%)和氟苯尼考(82.9%)耐药率在80.0%以上,多重耐药集中在4耐、6耐和9耐,主要检出的基因为fexA(40.0%,30/75)和femA(18.7%,14/75),其次为tetM(16.0%,12/75)、ermB(14.7%,11/75)和mecA(1.3%,1/75)。【结论】宠物犬源沙门氏菌和葡萄球菌耐药情况严重,耐药基因携带率高,使宠物犬的细菌性疾病治疗难度加大,应加强耐药菌的监测,降低宠物犬源耐药菌转移给人的潜在风险。 展开更多
关键词 宠物犬 沙门氏菌 葡萄球菌 耐药性 耐药基因检测
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The epigallocatechin gallate derivative Y6 reverses drug resistance mediated by the ABCB1 transporter both in vitro and in vivo
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作者 Yan Wen Ruiqiang Zhao +10 位作者 Pranav Gupta Yingfang Fan Yunkai Zhang Zhenguang Huang Xiaohui Li Yuangang Su Lijuan Liao Yu-An Xie Donghua Yang Zhe-Sheng Chen Gang Liang 《药学学报:英文版》 CSCD 2019年第2期316-323,共8页
Previously, we reported that Y6, a new epigallocatechin gallate derivative, is efficacious in reversing doxorubicin(DOX)–mediated resistance in hepatocellular carcinoma BEL-7404/DOX cells. In this study, we evaluated... Previously, we reported that Y6, a new epigallocatechin gallate derivative, is efficacious in reversing doxorubicin(DOX)–mediated resistance in hepatocellular carcinoma BEL-7404/DOX cells. In this study, we evaluated the efficacy of Y6 in reversing drug resistance both in vitro and in vivo by determining its effect on the adenosine triphosphate-binding cassette protein B1 transporter(ABCB1 or P-glycoprotein, P-gp). Our results showed that Y6 significantly sensitized cells overexpressing the ABCB1 transporter to anticancer drugs that are ABCB1 substrates. Y6 significantly stimulated the adenosine triphosphatase activity of ABCB1. Furthermore, Y6 exhibited a higher docking score as compared with epigallocatechin gallate inside the transmembrane domain of ABCB1. In addition, in the nude mousetumor xenograft model, Y6(110 mg/kg, intragastric administration), in combination with doxorubicin(2 mg/kg, intraperitoneal injection), significantly inhibited the growth of BEL-7404/DOX cell xenograft tumors, compared to equivalent epigallocatechin gallate. In conclusion, Y6 significantly reversed ABCB1-mediated multidrug resistance and its mechanisms of action may result from its competitive inhibition of the ABCB1 drug efflux function. 展开更多
关键词 EPIGALLOCATECHIN gallate(EGCG) 5 3’ 4’ 3″ 4″ 5″-6-O-ethylEGCG(Y6) Drug RESISTANCE RESISTANCE reversal ABCB1 P-gp
华北地区部分省(市)奶牛乳房炎乳中链球菌耐药表型和耐药基因研究
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作者 田晓英 甄天元 +4 位作者 于忠娜 孙萍 王军 韩荣伟 王世清 《黑龙江畜牧兽医》 CAS 北大核心 2019年第1期1-7,共7页
为了解华北地区4个省(市)奶牛乳房炎乳中链球菌的感染情况及对常用抗生素的耐药性,试验采用EN液体培养基、5%绵羊鲜血琼脂培养基、触酶试验、6.5%NaCl试验、七叶苷试验i马尿酸钠试验和CAMP试验对2016年华北地区240批次乳房炎奶牛乳样进... 为了解华北地区4个省(市)奶牛乳房炎乳中链球菌的感染情况及对常用抗生素的耐药性,试验采用EN液体培养基、5%绵羊鲜血琼脂培养基、触酶试验、6.5%NaCl试验、七叶苷试验i马尿酸钠试验和CAMP试验对2016年华北地区240批次乳房炎奶牛乳样进行链球菌的分离鉴定和分型;采用纸片扩散法对2016年华北地区分离出的链球菌进行药敏试验,对华北地区上下半年及4个省(市)链球菌的药敏情况进行对比;并通过PCR扩增技术研究链球菌的耐药基因,计算链球菌表型耐药率与所携带相关耐药基因的阳性率,比较两者的相符率。结果表明:共分离得到致病性链球菌28株,总分离率为11.67%,其中无乳链球菌7株、停乳链球菌5株和乳房链球菌16株;链球菌分离株对苯唑西林和青霉素G表现出完全耐药;对四环素类药物耐药性较高,强力霉素和四环素的耐药率分别为85.71%和82.14%;对氯霉素类药物高度敏感,敏感率为92.86%;对喹诺酮类和氨基糖苷类药物耐药性较低,平均耐药率分别为8.93%和10.20%;除磺胺类药物外,其他类药物耐药率下半年均低于上半年;在4个省(市)中,天津市链球菌分离株对各类抗生素的平均耐药率高于其他省(市);经PCR扩增检测,耐药基因阳性率在7.14%~26.79%之间,整体检出率较低,耐药基因与耐药表型相符率在0~100%之间,其中氯霉素相符率为0,并不能完全拟合。说明2016年我国华北地区链球菌总检出率较低,乳房链球菌为主要致病菌,链球菌分离株表现出不同程度的耐药性,且多为多重耐药,耐药基因与耐药表型的相符率较低。 展开更多
关键词 奶牛乳房炎 链球菌 分型 抗生素 耐药性 耐药基因
Mechanical, tribological and anti-corrosive properties of polyaniline/graphene coated Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys
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作者 Rita Maurya Abdul Rahim Siddiqui +1 位作者 Prvan Kumar Katiyar Kantesh Balani 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第8期1767-1778,共12页
The mechanical,tribological and corrosion protection offered to Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys by the epoxy coating containing polyaniline/graphene(PANI/Gr)pigments is undertaken in the current work.PANI... The mechanical,tribological and corrosion protection offered to Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys by the epoxy coating containing polyaniline/graphene(PANI/Gr)pigments is undertaken in the current work.PANI/Gr containing coatings were observed to be strongly adherent with a higher scratch hardness(Hs)and plowing hardness(Hp),i.e.Hsof 0.43 GPa,and Hpof 0.61 GPa,respectively when compared to that of neat epoxy coating(Hsof 0.17 GPa,and Hpof 0.40 GPa,respectively).Due to their higher Hsand Hpvalues,PANI/Gr based coatings displayed an enhanced wear resistance(Wear volume,Wv=4.53×10^-3 m^3)than that of neat epoxy coating(Wv=5.15×10^-3 m^3).The corrosion protection efficiency in corrosive environment of 3.5 wt%NaCl solution was obtained to be>99% for PANI/Gr containing coatings when compared to that of neat epoxy coating.The charge-transfer resistance(R(ct))of the PANI/Gr containing coatings were estimated to be>10^6 cm^2,which indicates their highly protective nature when compared to that of neat epoxy coating(R(ct)10^5 Ω cm^2).Hence,PANI/Gr containing coatings can be potentially used for wear resistance and corrosion protection applications in marine environments. 展开更多
关键词 MG-LI ALLOYS Scratch HARDNESS PLOWING HARDNESS Wear RESISTANCE Corrosion protection efficiency Charge transfer RESISTANCE
Development of Helicobacter pylori treatment: How do we manage antimicrobial resistance? 预览
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作者 Sho Suzuki Mitsuru Esaki +2 位作者 Chika Kusano Hisatomo Ikehara Takuji Gotoda 《世界胃肠病学杂志:英文版》 SCIE CAS 2019年第16期1907-1912,共6页
Helicobacter pylori (H. pylori) antimicrobial resistance is an urgent, global issue. In 2017, the World Health Organization designated clarithromycin-resistant H. pylori as a high priority bacterium for antibiotic res... Helicobacter pylori (H. pylori) antimicrobial resistance is an urgent, global issue. In 2017, the World Health Organization designated clarithromycin-resistant H. pylori as a high priority bacterium for antibiotic research and development. In addition to clarithromycin, resistance to metronidazole and fluoroquinolones has also increased worldwide. Recent international guidelines for management of H. pylori infection recommend bismuth or non-bismuth quadruple therapy for 14 d as a first-line treatment for H. pylori in areas of high clarithromycin and/or metronidazole resistance. Although these treatment regimens provide acceptable H. pylori eradication rates, the regimens used should not contribute to future resistance of H. pylori to antimicrobials. Moreover, these regimens can promote resistance, due to prolonged therapy with multiple antibiotics. A new strategy that can eradicate H. pylori as well as reduce the antibiotics used is required to prevent future antimicrobial resistance in H. pylori. Dual-therapy with vonoprazan and amoxicillin could be a breakthrough for H. pylori eradication in an era of growing antimicrobial resistance. This regimen may provide a satisfactory eradication rate of H. pylori and also minimize antimicrobial resistance due to single antibiotic use and the strong inhibitory effect of vonoprazan on gastric acid secretion. 展开更多
关键词 HELICOBACTER PYLORI Antibiotic RESISTANCE ANTIMICROBIAL RESISTANCE Dual therapy Vonoprazan
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Degradation of extracellular genomic, plasmid DNA and specific antibiotic resistance genes by chlorination
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作者 Menglu Zhang Sheng Chen +2 位作者 Xin Yu Peter Vikesland Amy Pruden 《环境科学与工程前沿(英文)》 SCIE EI CAS CSCD 2019年第3期115-126,共12页
There is a need to improve understanding of the effect of chlorine disinfection on antibiotic resistance genes (ARGs) in order to advance relevant drinking water, wastewater, and reuse treatments. However, few studies... There is a need to improve understanding of the effect of chlorine disinfection on antibiotic resistance genes (ARGs) in order to advance relevant drinking water, wastewater, and reuse treatments. However, few studies have explicitly assessed the physical effects on the DNA. Here we examined the effects of free chlorine (1-20 mg CI2/L) on extracellular genomic, plasmid DNA and select ARGs. Chlorination was found to decrease the fluorometric signal of extracellular genomic and plasmid DNA (ranging from 0.005 to 0.05 μg/mL) by 70%, relative to a no-chlorine control. Resulting DNA was further subject to a fragment analysis using a Bioanalyzer, indicating that chlorination resulted in fragmentation. Moreover, chlorine also effectively deactivated both chromosomal- and plasmidborne ARGs, mecK and tetA., respectively. For concentrations >2 mg CI2//L× 30 min, chlorine efficiently reduced the qPCR signal when the initial concentration of ARGs was 10^5 copies/μL or less. Notably, genomic DNA and mecA gene signals were more readily reduced by chlorine than the plasmid-bome tetK gene (by ~2 fold). Based on the results of qPCR with short (~200 bps) and long amplicons (-1200 bps), chlorination could destroy the integrity of ARGs, which likely reduces the possibility of natural transformation. Overall, our findings strongly illustrate that chlorination could be an effective method for inactivating extracellular chromosomal- and plasmid-bome DNA and ARGs. 展开更多
关键词 Antibiotic RESISTANCE Antibiotic RESISTANCE GENES (ARGs) EXTRACELLULAR DNA/ARGs CHLORINATION
采用基于雷诺平均的N-S方程和势流方法进行散货船阻力和运动的预报研究 预览
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作者 Hafizul Islam Mashiur Rahaman +1 位作者 M.Rafiqul Islam Hiromichi Akimoto 《船舶与海洋工程学报:英文版》 CSCD 2019年第3期271-281,共11页
Resistance prediction of ships using computational fluid dynamics has gained popularity over the years because of its high accuracy and low cost. This paper conducts numerical estimations of the ship resistance and mo... Resistance prediction of ships using computational fluid dynamics has gained popularity over the years because of its high accuracy and low cost. This paper conducts numerical estimations of the ship resistance and motion of a Japan bulk carrier model using SHIP_Motion, a Reynolds-averaged Navier–Stokes (RaNS)-based solver, and HydroSTAR, a commercial potential flow (PF)-based solver. The RaNS solver uses an overset-structured mesh and discretizes the flow field using the finite volume method, while the PF-based solver applies the three-dimensional panel method. In the calm water test, the total drag coefficient, sinkage, and trim were predicted using the RaNS solver following mesh dependency analysis, and the results were compared with the available experimental data. Next, calm water resistance was investigated for a range of Froude numbers. The added resistance in short-wave cases was simulated using both RaNS and PF solvers, and the results were compared. The PF solver showed better agreement with the RaNS solver for predicting motion responses than for predicting added resistance. While the added resistance results could not be directly validated because of the absence of experimental data, considering the previous accuracy of the RaNS solver in added resistance prediction and general added resistance profile of similar hull forms (bulk carriers), the prediction results could be concluded to be reliable. 展开更多
关键词 COMPUTATIONAL ship HYDRODYNAMICS Japan bulk CARRIER RaNS SIMULATION Potential flow SIMULATION Total drag RESISTANCE Added RESISTANCE
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Distribution and removal of antibiotic resistance genes during anaerobic sludge digestion with alkaline, thermal hydrolysis and ultrasonic pretreatments
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作者 Mengli Wang Ruying Li Qing Zhao 《环境科学与工程前沿(英文)》 SCIE EI CAS CSCD 2019年第3期163-172,共10页
Sewage sludge in the wastewater treatment plants contains considerable amount of antibiotic resistance genes (ARGs). A few studies have reported that anaerobic digestion (AD) could successfully remove some ARGs from s... Sewage sludge in the wastewater treatment plants contains considerable amount of antibiotic resistance genes (ARGs). A few studies have reported that anaerobic digestion (AD) could successfully remove some ARGs from sewage sludge, but information on the fate of ARGs in sludge pretreatment-AD process is still very limited. In this study, three sludge pretreatment methods, including alkaline, thermal hydrolysis and ultrasonic pretreatments, were compared to investigate the distribution and removal of ARGs in the sludge pretreatment-AD process. Results showed that the ARGs removal efficiency of AD itself was approximately 50.77%, and if these three sludge pretreatments were applied, the total ARGs removal efficiency of the whole pretreatment-AD process could be improved up to 52.50%-75.07%. The ultrasonic pretreatment was more efficient than alkaline and thermal hydrolysis pretreatments. Although thermal hydrolysis reduced ARGs obviously, the total ARGs rebounded considerably after inoculation and were only removed slightly in the subsequent AD process. Furthermore, it was found that the total ARGs concentration significantly correlated with the amount of 16S rRNA gene during the pretreatment and AD processes, and the bacteria carrying ARGs could be mainly affiliated with Proteobacteria. 展开更多
关键词 TETRACYCLINE RESISTANCE GENES SULFONAMIDE RESISTANCE GENES 16S rRNA gene SLUDGE pretreatment ANAEROBIC SLUDGE digestion
Improved corrosion resistance of Mg alloy AZ31B induced by selective evaporation of Mg using large pulsed electron beam irradiation
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作者 Woo Jin Lee Jisoo Kim Hyung Wook Park 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第5期891-901,共11页
Large pulsed electron beam(LPEB) irradiation was employed as a surface treatment of magnesium(Mg)alloy AZ31B to enhance its corrosion and wear resistance. Selective evaporation of Mg induced by LPEB irradiation at an ... Large pulsed electron beam(LPEB) irradiation was employed as a surface treatment of magnesium(Mg)alloy AZ31B to enhance its corrosion and wear resistance. Selective evaporation of Mg induced by LPEB irradiation at an energy density of 5J/cm^2 for 40 cycles has led to the formation of an Al-enriched resolidified layer with nano-grained structure consisting of Mg3.1 Al0.9 metastable phase. The formation of such a re-solidified layer after LPEB irradiation has enabled a decrease in corrosion rate of Mg alloy AZ31B in 3.5% NaCl solution. Different equivalent electrical circuit models were proposed to account for the corrosion behavior of untreated Mg alloy AZ31B and those subjected to LPEB irradiation. A decrease in wear depth when compared to that of the untreated alloy suggests an increase in wear resistance of LPEB-irradiated Mg alloy AZ31B. Adhesive wear is the predominant mechanism of untreated Mg alloy AZ31B while abrasive wear mechanism dominates for LPEB-irradiated Mg alloy AZ31B. 展开更多
关键词 Magnesium alloys Electron beam treatment Corrosion RESISTANCE Microstructure Rapid re-solidification Wear RESISTANCE
金属铝管影响下磁共振耦合线圈特性参数变化 预览
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作者 王乃健 李长生 +1 位作者 曹娟 缪东辉 《火力与指挥控制》 CSCD 北大核心 2019年第1期23-28,33共7页
为了探究金属物体对磁共振耦合线圈自身特性参数的影响规律,针对现有理论模型不能完全描述金属铝管对线圈特性参数影响规律的问题,构建了金属铝管影响下的磁共振耦合单线圈修正模型,对应开展了仿真与实验研究,并给出了涡电流回路映射电... 为了探究金属物体对磁共振耦合线圈自身特性参数的影响规律,针对现有理论模型不能完全描述金属铝管对线圈特性参数影响规律的问题,构建了金属铝管影响下的磁共振耦合单线圈修正模型,对应开展了仿真与实验研究,并给出了涡电流回路映射电阻R’E和电阻修正量RC具体表达式。研究规律表明:线圈电感参数变化量△L随间隙的增大而减小;线圈电阻参数变化量△R的变化趋势与间隙相关且存在变化趋势分界点,即当铝管与线圈间隙小于10 mm时,线圈电阻参数数值相对放置于空气中是增大的;当铝管与线圈间隙达到15 mm时,线圈电阻参数数值相对放置于空气中是减小的。 展开更多
关键词 金属铝管 磁共振耦合线圈 电阻 电感 电阻修正量
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Low nutrient levels as drinking water conditions can reduce the fitness cost of efflux pump-mediated ciprofloxacin resistance in Pseudomonas aeruginosa
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作者 Wenfang Lin Kun Wan +3 位作者 Jie Zeng Jingjing Li Xi Li Xin Yu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第9期123-132,共10页
The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usual... The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usually confers a fitness cost in bacteria. In this study, we aimed to determine why antibiotic resistance conferred by overexpression of an efflux pump persisted in low-nutrient environments(TOC < 10 mg/L) such as drinking and source water in which antibiotic selective pressure might be very low or even absent.Competition experiments between wild-type Pseudomonas aeruginosa and ciprofloxacinresistant mutants revealed that the fitness cost of ciprofloxacin resistance significantly decreased(p < 0.05) under low-nutrient(0.5 mg/L total organic carbon(TOC)) relative to high-nutrient(500 mg/L TOC) conditions. Mechanisms underlying this fitness cost were analyzed. The mexD gene expression in resistant bacteria(cip3 strain) was significantly lower(p < 0.05) in low-nutrient conditions, with 10 mg/L TOC((8.01 ± 0.82)-fold), than in high-nutrient conditions, with 500 mg/L TOC((48.89 ± 4.16)-fold). Moreover, rpoS gene expression in resistant bacteria((1.36 ± 0.13)-fold) was significantly lower(p < 0.05) than that in the wild-type strain((2.78 ± 0.29)-fold) under low-nutrient conditions(10 mg/L TOC),suggesting a growth advantage. Furthermore, the difference in metabolic activity between the two competing strains was significantly smaller(p < 0.05) in low-nutrient conditions(5 and 0.5 mg/L TOC). These results suggest that nutrient levels are a key factor in determining the persistence of antibiotic resistance conferred by efflux pumps in the natural environment with trace amounts or no antibiotics. 展开更多
关键词 EFFLUX pumps Antibiotic RESISTANCE Fitness cost LOW NUTRIENT nfxB mutation CIPROFLOXACIN RESISTANCE
四川部分区域鸽源沙门菌耐药表型及耐药基因检测
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作者 张跃东 罗薇 +3 位作者 张焕容 任玉鹏 葛润洲 杨劲松 《畜牧与兽医》 北大核心 2019年第2期52-58,共7页
为了解四川省成都市及周边区域鸽源沙门菌的耐药表型及耐药基因携带情况,通过常规细菌分离鉴定并结合PCR方法,获得42株鸽源沙门菌,采用K-B纸片法,选取20种抗生素,对42株鸽源沙门菌进行药敏试验,并结合PCR方法对其耐药基因携带情况进行... 为了解四川省成都市及周边区域鸽源沙门菌的耐药表型及耐药基因携带情况,通过常规细菌分离鉴定并结合PCR方法,获得42株鸽源沙门菌,采用K-B纸片法,选取20种抗生素,对42株鸽源沙门菌进行药敏试验,并结合PCR方法对其耐药基因携带情况进行检测。结果显示:受检菌对链霉素、四环素、多西环素耐药率为88. 1%;对阿莫西林耐药率为83. 3%;对头孢拉定、氨苄西林、萘啶酸的耐药率为81. 0%。42株沙门菌皆有不同程度的多重耐药性,其中33株同时耐4种以上抗生素,占检测菌株的78. 6%(33/42),主要的耐药谱为CTX-CRO-FLO-CPIOFL-AKN。42株沙门菌喹诺酮类耐药基因aac (6’)-Ib-cr检出率最高,为88. 09%(37/32);氨基糖苷类耐药基因aadA1、aph (3)Ⅱ、aac(3)Ⅱ检出率分别为80. 95%(34/42)、76. 19%(32/42)、16. 67%(7/42);β-内酰胺类耐药基因blaTEM-1、bla CMY-2检出率分别为42. 86%(18/42)、19. 04%(8/42);四环素类耐药基因tet M、tet A、tet B检出率分别为40. 4%(17/42)、38. 09%(16/42)、9. 52%(4/42);磺胺类耐药基因sul2检出率为80. 95%(34/42);喹诺酮类耐药基因qnrA检出率为38. 09%(16/42)。结果表明:四川省成都市及周边区域鸽源沙门菌存在普遍耐药,且多重耐药较为严重,耐药基因携带率高。 展开更多
关键词 沙门菌 耐药性 耐药基因 四川
Effects of Metformin Treatment on Soluble Leptin Receptor Levels in Women with Polycystic Ovary Syndrome 预览
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作者 Ru-biao LIU Yi LIU +3 位作者 Li-qun LV Wei XIAO Cheng GONG Jian-xin YUE 《当代医学科学(英文)》 SCIE CAS 2019年第4期609-614,共6页
The effects of metformin treatment on soluble leptin receptor (sOB-R) levels in women with polycystic ovary syndrome (PCOS) were investigated.This prospective and open-label study was conducted by the Department of Ob... The effects of metformin treatment on soluble leptin receptor (sOB-R) levels in women with polycystic ovary syndrome (PCOS) were investigated.This prospective and open-label study was conducted by the Department of Obstetrics & Gynecology at Union Hospital,Tongji Medical College of Huazhong University of Science and Technology,China.Fifty-five women with PCOS and insulin resistance (IR) were treated with metformin for 6 months.According to body mass index (BMI),the patients were divided into two groups:lean PCOS group (BMI <23 kg/m^2,n=34) and overweight or obese PCOS group (BMI >23 kg/m^2,n=21).Before and after treatment,serum luteinizing hormone (LH),follicle stimulating hormone (FSH),testosterone (T),androstenedione (A),dehydroepiandrosterone sulfate (DHEAS),insulin and sOB-R levels were determined.Thirty-one BMI-matched ovulatory women served as controls.The results showed:(1) The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR),androgen levels and hirsutism scores were higher,and sOB-R levels were lower in PCOS groups than in control group.A subgroup analysis of lean and overweight or obese PCOS patients revealed there was significant difference in sOB-R level between lean PCOS group and overweight or obese PCOS group.There were no significant differences in anthropometric parameters between lean PCOS patients and BMI-matched controls.However,sOB-R level was significantly lower in lean PCOS women than in controls.(2) There was no correlation between sOB-R level and BMI,waist and hip circumference,total testosterone,androstendione,DHEAS,LH or hirsutism scores in PCOS patients,but there was a significant negative correlation between sOB-R and HOMA-IR.(3) After treatment with metformin for 6 months,serum insulin levels decreased,and sOB-R levels increased significantly (P<0.01).It was suggested that considering low sOB-R levels supposedly compensate diminished leptin action,PCOS per se might cause leptin resistance.It is likely that reduction of hyperinsulinemia produced by metformin effectively imp 展开更多
关键词 POLYCYSTIC OVARY syndrome METFORMIN insulin RESISTANCE LEPTIN RESISTANCE SOLUBLE LEPTIN receptor
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草地贪夜蛾对杀虫剂的抗性研究进展
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作者 王芹芹 崔丽 +3 位作者 王立 梁沛 袁会珠 芮昌辉 《农药学学报》 CAS CSCD 北大核心 2019年第4期401-408,共8页
草地贪夜蛾Spodoptera frugiperda (J. E. Smith)是一种杂食性害虫,原产于美洲热带和亚热带地区,于2019年1月在中国云南省首次被发现后,已迅速向广西、贵州、广东及湖南等地蔓延。草地贪夜蛾寄主广泛,常用化学防治药剂为有机磷类、氨基... 草地贪夜蛾Spodoptera frugiperda (J. E. Smith)是一种杂食性害虫,原产于美洲热带和亚热带地区,于2019年1月在中国云南省首次被发现后,已迅速向广西、贵州、广东及湖南等地蔓延。草地贪夜蛾寄主广泛,常用化学防治药剂为有机磷类、氨基甲酸酯类和拟除虫菊酯类,田间抗性监测数据显示,其对上述3类常用药剂已达中至高等抗性水平。此外,已有研究证明氯菊酯抗性草地贪夜蛾对二嗪类杀虫剂茚虫威无交互抗性;同时已有关于草地贪夜蛾对氟苯虫酰胺和氯虫苯甲酰胺田间和室内抗性的报道,表明其对上述2种药剂存在极高的交互抗性风险。草地贪夜蛾的抗药性机理主要涉及表皮穿透性降低、解毒作用增强和靶标敏感性下降等几方面,其中代谢解毒作用增强和靶标敏感性下降是导致草地贪夜蛾对杀虫剂产生抗性的主要机制。文章综述了草地贪夜蛾对传统杀虫剂和新型作用机制杀虫剂的抗性现状及抗性机理等方面的研究进展,以期对当前中国的草地贪夜蛾田间防治及抗性研究和防控提供参考。 展开更多
关键词 草地贪夜蛾 杀虫剂 抗药性 抗性机理 氯虫苯甲酰胺 氟苯虫酰胺 茚虫威
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