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Prediction for risk of disease progression among hospitalized COVID-19 patients
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作者 Jia-Shu Shen Qing-Qing Yang +7 位作者 Qiao-Xin Shi Hou-Yu Zhao Lin Zhuo Hai-Bo Song Yun Lu Si-Yan Zhan Hong Cheng Feng Sun 《Medical Data Mining》 2023年第2期41-49,共9页
Objective:The COVID-19 pandemic poses a significant threat to global health.Given the lack of studies on risk factors for COVID-19 progression at present,this study aimed to build a predictive model to predict the pro... Objective:The COVID-19 pandemic poses a significant threat to global health.Given the lack of studies on risk factors for COVID-19 progression at present,this study aimed to build a predictive model to predict the progression risk among hospitalized COVID-19 patients.Methods:We extracted data from 1074 mild and moderate COVID-19 patients from Electronic Health Records(EHRs)in a designated Wuhan hospital including demographic characteristics and clinical and laboratory information.Disease progression was defined as progressing to severe critical illness after admission.The LASSO regression was used to select the predicted variables and a logistic regression model was applied to build the predictive model.Nomogram was used to show the results.Results:Seven variables were included in the predictive model:age per 10 years(OR,1.15;95%CI,1.03-1.29),lactate dehydrogenase(OR,1.73;95%CI,1.14-2.62),neutrophil-to-lymphocyte ratio(OR,2.07;95%CI,1.42-3.02),eosinophil count(OR,2.10;95%CI,1.20-3.69),albumin(OR,2.37;95%CI,1.65-3.45),hemoglobin(OR,1.50;95%CI,1.10-2.05),D-dimer(OR,1.63;95%CI,1.19-2.23).The mean area under the receiver operating characteristic curve of the predictive model was 0.72(95%CI,0.69-0.76).Conclusions:This study built a predictive model that could effectively predict the progression risk among hospitalized COVID-19 patients. 展开更多
关键词 coronavirus disease 2019(COVID-19) predictive model disease progression
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The effect of estrogen-mediated ubiquitin on cardiovascular diseases:a bioinformatics analysis
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作者 Nan Li Yu-Han Duan Kun Zhang 《Precision Medicine Research》 2023年第1期3-8,共6页
Objective:Using data mining tools,study the potential pathways of estrogen’s cardiovascular effects.Methods:The GeneExpression Omnibus database was used to download the relevant high-throughput microarray dataset GSE... Objective:Using data mining tools,study the potential pathways of estrogen’s cardiovascular effects.Methods:The GeneExpression Omnibus database was used to download the relevant high-throughput microarray dataset GSE72180,which was then analyzed for differential genes using the GEO2R online analysis tool,gene function and pathway enrichment analysis using DAVID 6.8,protein interaction network analysis using the STRING database,and core network extraction using the MCODE algorithm.Results:A total of 131 differential genes were identified and enriched for gene function and signaling pathway analysis,which indicated that these genes were related with focal adhesion and the HIF-1 signaling pathway.MCODE algorithm analysis extracted 1 core sub-network of these genes to be related to ubiquitin protein transferase activity,protein polyubiquitination,protein ubiquitination involved in ubiquitin-dependent proteolytic metabolic processes,ligase activity,and clustering on ubiquitin-mediated protein hydrolysis signaling pathway.Conclusion:By using data mining tools,it is possible to identify how estrogen may influence the cardiovascular system by controlling the ubiquitination process.This information may be used as a reference for etiology and preventive studies of cardiovascular illnesses. 展开更多
关键词 ESTROGEN data mining CARDIOVASCULAR ubiquitination modification
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Enhancing Canola Yield and Photosynthesis under Water Stress with Hydrogel Polymers
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作者 Elham A.Badr Gehan Sh.Bakhoum +4 位作者 Mervat Sh.Sadak Ibrahim Al-Ashkar Mohammad Sohidul Islam Ayman El Sabagh Magdi T.Abdelhamid 《Phyton-International Journal of Experimental Botany》 SCIE 2024年第7期1623-1645,共23页
While Egypt’s canola production per unit area has recently grown,productivity remains low,necessitating increased productivity.Hydrogels are water-absorbent polymer compounds that can optimize irrigation schedules by... While Egypt’s canola production per unit area has recently grown,productivity remains low,necessitating increased productivity.Hydrogels are water-absorbent polymer compounds that can optimize irrigation schedules by increasing the soil’s ability to retain water.Accordingly,twofield experiments were conducted to examine hydrogel application to sandy soil on canola growth,biochemical aspects,yield,yield traits,and nutritional quality of yielded seeds grown under water deficit stress conditions.The experiments were conducted by arranging a split-plot layout in a randomized complete block design(RCBD)with three times replications of each treatment.While water stress at 75%or 50%of crop evapotranspiration(ETc)lowered chlorophyll a,chlorophyll b,caro-tenoids,and total pigments content,indole-3-acetic acid,plant development,seed yield,and oil and total carbo-hydrates of seed yield,hydrogel treatment enhanced all of the traits mentioned above.Furthermore,hydrogel enhanced to gather compatible solutes(proline,amino acids,total soluble sugars),phenolics content in leaves,seed protein,and crop water productivity,which increased while the plants were under water stress.The results revealed that the full irrigation(100%ETc)along with hydrogel compared to water-stressed(50%ETc)led to enhanced seed yield(kg ha^(-1)),Oil(%),and Total carbohydrates(%)of rapeseed by 57.1%,11.1%and 15.7%,respectively.Likewise,under water-stressed plots with hydrogel exhibited enhancement by 10.0%,3.2%and 5.1%in seed yield(kg ha^(-1)),oil(%),and total carbohydrates(%)of rapeseed by 57.1%,11.1%and 15.7%,respec-tively compared to control.As a result,the use of hydrogel polymer will be a viable and practical solution for increasing agricultural output under water deficit stress situations. 展开更多
关键词 HYDROGEL oil OSMOLYTES RAPESEED YIELD water stress
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Construction of a fusion protein expression vector MK-EGFP and its subcellular localization in different carcinoma cell lines 被引量:6
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作者 Li-Cheng Dai Di-Yong Xu +5 位作者 Xing Yao Li-Shan Min Ning Zhao Bo-Ying Xu Zheng-Ping Xu Yong-Liang Lu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2006年第47期7649-7653,共5页
AIM: To construct an expression plasmid encoding hu-man wild-type midkine (MK) and enhanced green fluo-rescence protein (EGFP) fusion protein (MK-EGFP), and to analyze the subcellular localization of MK in different c... AIM: To construct an expression plasmid encoding hu-man wild-type midkine (MK) and enhanced green fluo-rescence protein (EGFP) fusion protein (MK-EGFP), and to analyze the subcellular localization of MK in different carcinoma cell lines.METHODS: Two kinds of MK coding sequences with or without signal peptide were cloned into plasmid pEGFP-N2, and the recombinant plasmids constructed were introduced into HepG2, MCF7 and DU145 cells, respectively, by transfection. With the help of laser scan-ning confocal microscopy, the expression and subcellular localization of MK-GFP fusion protein could be detected.RESULTS: Compared with the GFP control, in which fluorescence was detected diffusely over the entire cell body except in the nucleolus, both kinds of fusion pro-tein MK-GFP were localized exclusively to the nucleus and accumulated in the nucleolus in the three kinds of cancer cell lines.CONCLUSION: This study reveals the specific nucleolar translocation independent of signal peptide, which may be involved in the mechanism that MK works. It provides valuable evidence for further study on the functions of MK in nucleus and its possible mechanisms, in which ribosomal RNA transcription and ribosome assembly are involved. 展开更多
关键词 肝癌 核糖体 肝细胞 蛋白质 亚细胞
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Chemical composition of essential oil of Thymus vulgaris collected from Saudi Arabian market 被引量:1
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作者 Abdulrahman Khazim Al-Asmari Md Tanwir Athar +1 位作者 Ahmed Abdullah Al-Faraidy Mohammed Salim Almuhaiza 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2017年第2期147-150,共4页
Objective: To focus on the analysis of chemical constituents of the Thymus vulgaris L.(locally known as "Zaitra" or "Za'atar"; Family: Lamiaceae) which is available in the market of Saudi Arabi... Objective: To focus on the analysis of chemical constituents of the Thymus vulgaris L.(locally known as "Zaitra" or "Za'atar"; Family: Lamiaceae) which is available in the market of Saudi Arabia.Methods: The Zaitra oil was analyzed by gas chromatography-mass spectrometry. The mass spectra were compared with the standard spectra available in National Institute Standard and Technique library.Results: The results indicated that the Thymus oil is composed of many chemical compounds including a pinene, thymol and caryophyllene which are biologically active and also used in various diseases.Conclusions: It can be concluded that the Thymus vulgaris due to presence of many bioactive compounds can be used as a new potential source of medicine for the treatment of various types of illness. 展开更多
关键词 Essential oil GC–MS Saudi Arabian herbs Thymus vulgaris
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Evaluation of Preemergence Herbicides for Crop Safety and Weed Control in Safflower
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作者 Prashant Jha Vipan Kumar +1 位作者 Charlemagne A. Lim Ramawatar Yadav 《American Journal of Plant Sciences》 2017年第10期2358-2366,共9页
Weed management in safflower (Carthamus tinctorious L.) is a major challenge for growers due to very limited herbicide options available, particularly for broadleaf weed control. Field experiments were conducted at th... Weed management in safflower (Carthamus tinctorious L.) is a major challenge for growers due to very limited herbicide options available, particularly for broadleaf weed control. Field experiments were conducted at the Montana State University Southern Agricultural Research Center (MSU-SARC) near Huntley, MT in 2015 and 2016 to evaluate preemergence (PRE) soil-residual herbicides for crop safety and season-long broadleaf weed control in safflower. Among all herbicide programs tested, only sulfentrazone (105 g&middot;ai&middot;ha-1) alone or with pendimethalin (1064 g&middot;ai&middot;ha-1) caused 4% to 12% early-season visible injury to safflower, although the injury was not evident beyond 30 DAT. Sulfentrazone alone or with pendimethalin and pyroxasulfone (59 g&middot;ai&middot;ha-1) with pendimethalin had a season-long residual activity on kochia [Kochia scoparia (L.) Schrad] and Russian-thistle (Salsola tragus L), with 89% to 99% control at 60 DAT, and up to 98% reduction in weed density compared with dimethenamid-P (213 g&middot;ai&middot;ha-1) and S-metolachlor (433 g&middot;ai&middot;ha-1) at 65 DAT. Pyroxasulfone (59 or 118 g&middot;ai&middot;ha-1) alone or dimethenamid-P with pendimethalin provided a moderate to good control (65% to 79% at 60 DAT) of kochia and Russian-thistle. However, the end-season control of kochia or Russian-thistle was inadequate ( S-metolachlor alone program. Safflower grain yield with sulfentrazone alone or with pendimethalin, pyroxasulfone alone or with pendimethalin, and dimethenamid-P with pendimethalin averaged 3559 kg&middot;ha-1, which was 195% higher compared with the nontreated check. In conclusion, sulfentrazone and pyroxasulfone or dimethenamid-P in combination with pendimethalin will be effective PRE herbicide programs for kochia and Russian-thistle control in safflower. 展开更多
关键词 SAFFLOWER WEED Control PREEMERGENCE HERBICIDE Kochia Russian-Thistle
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Hyperbaric oxygen protects against PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion via the inhibition of cell apoptosis and autophagy
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作者 JIANRONG YANG WAN CHEN +7 位作者 XING ZHOU YAOXUAN LI ZHIHUANG NONG LIYUAN ZHOU XUAN WEI XIAORONG PAN CHUNXIA CHEN WENSHENG LU 《BIOCELL》 SCIE 2022年第1期137-148,共12页
In this study,we investigated the protective effect of hyperbaric oxygen(HBO)on PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion and its possible mechanism.PC12 and H9C2 cell oxygen-glucose d... In this study,we investigated the protective effect of hyperbaric oxygen(HBO)on PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion and its possible mechanism.PC12 and H9C2 cell oxygen-glucose deprivation/reperfusion model were established.Cells were divided into a control group,model group,hyperbaric air(HBA)group and HBO group.The cell viability was detected by the CCK8 assay.Hoechst 33342 and PI staining assays and mitochondrial membrane potential(MMP)assays were used to detect cell apoptosis.The ultrastructure of cells,including autophagosomes,lysosomes,and apoptosis,were examined using a transmission electron microscope.The expression of autophagy-related proteins was detected by cellular immunofluorescence and immunocytochemistry.Our results showed that HBO can significantly improve the vitality of damaged PC12 and H9C2 cells caused by oxygen–glucose deprivation/reperfusion.HBO can significantly inhibit apoptosis of PC12 and H9C2 cells caused by oxygenglucose deprivation/reperfusion.Importantly,we found that the protective mechanism of PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion may be related to the inhibition of the autophagy pathway.In this study,the results of cellular immunofluorescence and immunocytochemistry experiments showed that the 4E-BP1,p-AKt and mTOR levels of PC12 and H9C2 cells in the model group decreased,while the levels of LC3B,Atg5 and p53 increased.However,after HBO treatment,these autophagy-related indexes were reversed.In addition,observation of the cell ultrastructure with transmission electron microscopy found that in the model group,a significant increase in the number of autophagic vesicles was observed.In the HBO group,a decrease in autophagic vesicles was observed.The study demonstrated that hyperbaric oxygen protects against PC12 and H9C2 cell damage caused by oxygen-glucose deprivation/reperfusion via the inhibition of cell apoptosis and autophagy. 展开更多
关键词 Hyperbaric oxygen PC12 cells H9C2 cells Celoxygen-glucose deprivation/reperfusion Apoptosis AUTOPHAGY
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Correlation of bisphenol A action on genes interfering with estrogen signaling pathways and the development of endometriosis
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作者 Nan Li Yu-Han Duan +1 位作者 Lei Chen Kun Zhang 《Precision Medicine Research》 2022年第3期9-14,共6页
Bisphenol A(BPA),as an environmental endocrine disruptor,affects human health by interfering with hormone secretion in the body.Endometriosis(EMs)is an estrogendependent disease that is influenced by a variety of fac... Bisphenol A(BPA),as an environmental endocrine disruptor,affects human health by interfering with hormone secretion in the body.Endometriosis(EMs)is an estrogendependent disease that is influenced by a variety of factors such as genetics,oxidative stress,immunity,and environment for its onset.In recent years,special attention has been paid to the influence of genetic polymorphisms on the pathogenesis of EMs.A search of the Comparative Toxicology Database revealed that BPA can act on a variety of different genes to induce disease development by regulating gene expression and that some genes play equally important roles in the development of EMs.Among them,we selected four genes(EGFR,ESR2,FOS,KRAS)in the estrogen signaling pathway,and now we review the mechanism of BPA acting on these four genes in different ways and the role of these four genes in the development of EMs,which will provide a reference for the subsequent study of the mechanism of BPA involvement in the development of EMs. 展开更多
关键词 bisphenol A EMS EGFR ESR2 FOS KRAS
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Clinical significance of DNAH14 gene in uterine corpus endometrial carcinoma based on bioinformatics
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作者 Nan Li Yu-Han Duan +1 位作者 Lei Chen Kun Zhang 《Medical Data Mining》 2022年第3期59-64,共6页
Background:To analyze the effect of DNAH14 gene on the development of endometrial carcinoma and its clinical significance by using tumor comprehensive database.Methods:First,the aberrant expression of the DNAH14 gene ... Background:To analyze the effect of DNAH14 gene on the development of endometrial carcinoma and its clinical significance by using tumor comprehensive database.Methods:First,the aberrant expression of the DNAH14 gene in multiple tumor tissues was obtained in the gene expression profiling interactive analysis.Then clinicopathological data were obtained at the cancer genome atlas.The expression and prognostic value of the DNAH14 gene in endometrial cancer were assessed.Subsequently,Kaplan-Meier mapping instrument analysis was used to assess the significance of DNAH14 mRNA expression and DNAH14 gene mutations in the prognosis of uterine corpus endometrial carcinoma patients.The relationship between immune infiltrating cells and uterine corpus endometrial carcinoma survival was analyzed using the Tumor Immune Estimation Resource database.Finally,the Mu Target database was used to analyze and identify genes that exhibit altered expression in samples containing mutated genes,then the Database for Annotation,Visualization and Integrated Discovery was used to explore the biological processes closely associated with DNAH14 mutations and enriched signaling pathways,and the Search Tool for Recurring Instances of Neighbouring Genes database to construct protein interaction networks that may interact with DNAH14 and explore their potential mechanisms of action.Results:The overall survival rate and relapse-free survival rate in patients with high expression of DNAH14 were significantly lower than those with low expression and there were significant differences in clinical stage,age,menopausal status and histological types(P<0.05).DNAH14 gene mutation exists in patients with endometrial carcinoma,indicating a good prognosis.Correlation analysis showed that DNAH14 gene mutation might play a role through proteoglycan and Wnt,T cell receptor,toll-like receptor signal pathway in cancer.In addition,DNAH14 mutation is related to the level of immune infiltration;protein interaction analysis showed that DCTN3,HAP1,ACTR1,DNAH12,ACTR1B and other proteins interact with DNAH14.Conclusion:DNAH14 is highly expressed in endometrial carcinoma and its high expression is related to the poor prognosis of the patients.DNAH14 gene mutation in patients with endometrial carcinoma may affect the level of immune infiltration and improve prognosis through proteoglycan,Wnt,T cell receptor and toll-like receptor signal pathway in cancer.DNAH14 may be an index to judge the prognosis of patients with endometrial carcinoma. 展开更多
关键词 endometrial carcinoma DNAH14 gene mutation PROGNOSIS
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Desmoid type fibromatosis: A case report with an unusual etiology 被引量:2
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作者 Syed Faisal Jafri Obada Obaisi +4 位作者 Gerardo G Vergara Joe Cates Jaswinder Singh Jennifer Feeback Harathi Yandrapu 《World Journal of Gastrointestinal Oncology》 SCIE CAS 2017年第9期385-389,共5页
Desmoid type fibromatosis(DTF) is a rare, locally invasive, non-metastasizing soft tissue tumor. We report an interesting case of DTF involving the pancreatic head of a 54-year-old woman. She presented with intermitte... Desmoid type fibromatosis(DTF) is a rare, locally invasive, non-metastasizing soft tissue tumor. We report an interesting case of DTF involving the pancreatic head of a 54-year-old woman. She presented with intermittent dysphagia and significant weight loss within a 3-mo period. Laboratory findings showed mild elevation of transaminases, significant elevation of alkaline phosphatase and direct hyperbilirubinemia, indicating obstructive jaundice. Computerized tomography of the abdomen revealed a mass in the head of the pancreas, dilated common bile duct, and dilated pancreatic duct. Endoscopic retrograde cholangiopancreatography and endoscopic ultrasound showed a large hypoechoic massin the head of the pancreas causing extrahepatic biliary obstruction and pancreatic ductal dilation. The patient underwent a successful partial pancreatico-duodenectomy and cholecystectomy. She received no additional therapy after surgery, and liver function tests were normalized within nine days after surgery. Currently, surgical resection is the recommended first line treatment. The patient will be followed for any recurrence. 展开更多
关键词 Desmoid type fibromatosis Desmoid tumor Aggressive fibromatosis Pancreas Painless jaundice
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Using Pyroxasulfone for Downy Brome (<i>Bromus tectorum</i>L.) Control in Winter Wheat
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作者 Vipan Kumar Prashant Jha Amit J. Jhala 《American Journal of Plant Sciences》 2017年第10期2367-2378,共12页
Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for... Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for use in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield&#8482) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the three studies. Downy brome injury with pyroxasulfone preemergence (PRE) only program did not differ between 89 or 178 g&middot;ai (active ingredient)&middot;ha-1 rates, and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown program, the addition of pyroxasulfone (178 g&middot;ai&middot;ha-1) to glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE (84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water dispersible granule (WDG) formulation of pyroxasulfone performed slightly better than the suspension concentrate (SC) formulation for downy brome injury. Pyroxasulfone applied PRE in the fall at a rate of 89 g&middot;ai&middot;ha-1 followed by (fb) imazamox (44 g&middot;ai&middot;ha-1 rate) applied postemergence (POST) in the spring effectively controlled downy brome (99% end-season injury). Furthermore, the injury was consistent with the standard program comprising of propoxycarbazone (29 g&middot;ai&middot;ha-1) PRE fb imazamox POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST herbicide program for a season-long downy brome management in winter wheat. 展开更多
关键词 Downy Brome Pyroxasulfone Soil-Applied HERBICIDE HERBICIDE Rate Application TIMING Formulation WHEAT
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Revitalizing the Countryside Through Rural and Agricultural Modernization
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作者 WANG LI 《China Today》 2021年第4期38-40,共3页
DEVELOPMENT of rural areas is critical for China.When working toward the goal of building the country into a moderately prosperous society in all respects and a strong,modern socialist country,the most challenging and... DEVELOPMENT of rural areas is critical for China.When working toward the goal of building the country into a moderately prosperous society in all respects and a strong,modern socialist country,the most challenging and onerous tasks China faces are those regarding rural areas.The progress of these areas will in turn provide the solid foundation and become the largest source of strength and potential for national development. 展开更多
关键词 AGRICULTURAL RURAL China.
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Field efficacy of insect pathogen, botanical, and jasmonic acid for the management of wheat midge Sitodiplosis mosellana and the impact on adult parasitoid Macroglenes penetrans populations in spring wheat 被引量:4
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作者 Govinda Shrestha Gadi V. P. Reddy 《Insect Science》 SCIE CAS CSCD 2019年第3期523-535,共13页
The wheat midge, Sitodiplosis mosellana, is a serious pest of wheat worldwide. In North America, management of S. mosellana in spring wheat relies on the timely application of pesticides, based on midge adults levels ... The wheat midge, Sitodiplosis mosellana, is a serious pest of wheat worldwide. In North America, management of S. mosellana in spring wheat relies on the timely application of pesticides, based on midge adults levels caught in pheromone traps or seen via field scouting during wheat heading. In this context, biopesticides can be an effective alternative to pesticides for controlling S. mosellana within an Integrated Pest Management program. A field study using insect pathogenic fungus Beauveria bassiana GHA, nematode Steinernema Jeltiae with Barricade polymer gel 1%, pyrethrin, combined formulations of B. bassiana GHA and pyrethrin, Jasmonic acid (JA) and chlorpyrifos (chemical check) was performed to determine to which extent they affect midge larval populations, kernel damage levels, grain yield, and quality, and the impacts on adult parasitoid Macroglenes penetrans populations. The results indicated that biopesticides JA and S. Jeltiae were the most effective in reducing larval populations and kernel damage levels, and produced a higher spring wheat yield when compared to the water control at both study locations (East Valier and North Valier, Montana, USA). Increased test weight in wheat had been recorded with two previous biopesticides at East Valier but not for North Valier, when compared over water control. These results were comparable in efficacy to the chlorpyrifos. This study also suggested that B. bassiana and pyrethrin may work synergistically, as exemplified by lower total larval populations and kernel damage levels when applied together. This study did not demonstrate the effect of any treatments on M. penetrans populations. 展开更多
关键词 biological control BIOPESTICIDES ENTOMOPATHOGEN Integrated PEST MANAGEMENT
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Synthesis and Characterization of pH-Responsive Block Copolymers with Primary Amine Groups
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作者 WANG Hong ZHU Yue-jun +2 位作者 REN Xiao-na ZHANG Hong TAN Ye-bang 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2013年第2期389-395,共7页
A new pH-responsive block copolymer, methoxy poly(ethylene glycol)-b-poly[5-methacrylamido- pentylamine hydrochloride](mPEG-b-PMAAPA) was synthesized and characterized in this paper. The monomer 5-methacrylamido-p... A new pH-responsive block copolymer, methoxy poly(ethylene glycol)-b-poly[5-methacrylamido- pentylamine hydrochloride](mPEG-b-PMAAPA) was synthesized and characterized in this paper. The monomer 5-methacrylamido-pentylamine hydrochloride(MAAPA) and the macroinitiator(mPEG-ACVA) were synthesized, re- spectively, and mPEG-b-PMAAPA was then obtained by free radical polymerization. The structure and molecular weight of mPEG-b-PMAAPA were cont]rmed by hydrogen nuclear magnetic resonance(~H NMR) spectroscopy and gel permeation chromatography with multiangle laser light scattering(GPC-MALLS) measurements. At a low pH, it is hydrophilic due to the protonation of the primary amine groups. With increasing pH value, deprotonation occurs and the hydrophobicity of PMAAPA block increases. This molecular feature leads to interesting aggregation behavior of mPEG-b-PMAAPA in aqueous solutions at different pH values as revealed by dynamic light scattering(DLS) measurements, transmission electron microscopy(TEM) observations and resonance light scattering(RLS) measure- ments. 展开更多
关键词 Block copolymer POLYAMINE PH-RESPONSIVE Water soluble copolymer
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