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Salting-Out Assisted Liquid-Liquid Extraction Combined with HPLC for Quantitative Extraction of Trace Multiclass Pesticide Residues from Environmental Waters

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American Journal of Analytical Chemistry 2017年第7期8卷 433-448页

作者： Yosef alemayehu Teshome Tolcha Negussie Megersa Department of Environmental Science College of Agriculture and Environmental Sciences University of South Africa Pretoria South Africa Department of Chemistry College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia

In this study, salting-out assisted liquid-liquid extraction combined with high performance liquid chromatography diode array detector (SALLE-HPLC-DAD) method was developed and validated for simultaneous analysis of carbaryl, atrazine, propazine, chlorothalonil, dimethametryn and terbutryn in environmental water samples. Parameters affecting the extraction efficiency such as type and volume of extraction solvent, sample volume, salt type and amount, centrifugation speed and time, and sample pH were optimized. Under the optimum extraction conditions the method was linear over the range of 10 - 100 μg/L (carbaryl), 8 - 100 μg/L (atarzine), 7 - 100 μg/L (propazine) and 9 - 100 μg/L (chlorothalonil, terbutryn and dimethametryn) with correlation coefficients (R2) between 0.99 and 0.999. Limits of detection and quantification ranged from 2.0 to 2.8 μg/L and 6.7 to 9.5 μg/L, respectively. The extraction recoveries obtained for ground, lake and river waters were in a range of 75.5% to 106.6%, with the intra-day and inter-day relative standard deviation lower than 3.4% for all the target analytes. All of the target analytes were not detected in these samples. Therefore, the proposed SALLE-HPLC-DAD method is simple, rapid, cheap and environmentally friendly for the determination of the aforementioned herbicides, insecticide and fungicide residues in environmental water samples.

关键词： Environmental Waters High Performance Liquid Chromatography Salting-Out Assisted Liquid-Liquid Extraction Southern Ethiopia Trace Multiclass Pesticide Residues

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Numerical Solution of the Coupled Viscous Burgers’ Equation Using Differential Quadrature Method Based on Fourier Expansion Basis

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Applied Mathematics 2018年第7期9卷 821-835页

作者： Masho Jima alemayehu Shiferaw Ali Tsegaye Department of Mathematics Jimma University Jimma Ethiopia

The differential quadrature method based on Fourier expansion basis is applied in this work to solve coupled viscous Burgers’ equation with appropriate initial and boundary conditions. In the first step for the given problem we have discretized the interval and replaced the differential equation by the Differential quadrature method based on Fourier expansion basis to obtain a system of ordinary differential equation (ODE) then we implement the numerical scheme by computer programing and perform numerical solution. Finally the validation of the present scheme is demonstrated by numerical example and compared with some existing numerical methods in literature. The method is analyzed for stability and convergence. It is found that the proposed numerical scheme produces a good result as compared to other researcher’s result and even generates a value at the nodes or mesh points that the results have not seen yet.

关键词： Differential Quadrature Method Fourier Expansion Coupled Viscous Coupled Viscous Burgers’ Equation Initial and Boundary Conditions

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Fast Finite Difference Solutions of the Three Dimensional Poisson’s Equation in Cylindrical Coordinates

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American Journal of Computational Mathematics 2013年第4期3卷 356-361页

作者： alemayehu Shiferaw R. C. Mittal Department of Mathematics Indian Institute of Technology Roorkee India

In this work, the three-dimensional Poisson’s equation in cylindrical coordinates system with the Dirichlet’s boundary conditions in a portion of a cylinder for is solved directly, by extending the method of Hockney. The Poisson equation is approximated by second-order finite differences and the resulting large algebraic system of linear equations is treated systematically in order to get a block tri-diagonal system. The accuracy of this method is tested for some Poisson’s equations with known analytical solutions and the numerical results obtained show that the method produces accurate results.

关键词： Poisson’s Equation Hockney’s Method Thomas Algorithm

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Genetic Variation for Grain Yield and Yield Related Traits in Tef [<i>Eragrostis tef</i>(Zucc.)Trotter] under Moisture Stress and Non-Stress Environments

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American Journal of Plant Sciences 2012年第8期3卷 1041-1046页

作者： Wondewosen Shiferaw alemayehu Balcha Hussen Mohammed Department of Plant and Horticultural Sciences Hawassa University Hawassa Ethiopia Jinka Agricultural Research Centre South Agricultural Research Institute Hawassa Ethiopia School of Agricultural Science Dilla University Dilla Ethiopia

Tef [Eragrostis tef (Zucc.)Trotter] is an ancient and major cereal crop in Ethiopia. Increasing tef grain yield partly requires developing cultivars that are adapted to drought stress environment. An experiment was carried out using 18 tef genotypes grown during September to December, 2010, under two water supply environments (stress during grain filling period, and non-stress) to identify genetic variation, heritability and correlations of grain yield and yield related traits. Broad-sense heritability values under respective stress and non-stress environments were grain yield (g/m2) 0.80 and 0.89, total biomass (g/m2) 0.89 and 0.73, harvest index 0.69 and 0.79, panicle weight (g/plant) 0.93 and 0.92, and seed weight (g/plant) 0.96 and 0.86. The correlations of grain yield under respective stress and non-stress environments were total biomass rp = 0.64, rg = 0.70, and rp = 0.48, rg = 0.56, harvest index rp = 0.70, rg = 0.64, and rp = 0.87, rg = 0.90, panicle weight rp = 0.98, rg = 1.00, and rp = 0.96, rg = 1.00, and seed weight/plant rp = 0.98, rg = 1.00, and rp = 0.90, rg = 1.00. The present experiment showed that either grain yield per se, or seed weight/plant could be used to improve grain yield under stress and non-stress environments.

关键词： Variability Broad-Sense Heritability Correlations Moisture Stress Eragrostis tef

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Prevalence of diarrhea and associated risk factors among children under-five years of age in Eastern Ethiopia: A cross-sectional study

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Open Journal of Preventive Medicine 2013年第7期3卷 446-453页

作者： Bezatu Mengistie Yemane Berhane alemayehu Worku Addis Continental Institute of Public Health Addis Ababa Ethiopia School of Public Health Addis Ababa University Addis Ababa Ethiopia College of Health Sciences Haramaya University Harar Ethiopia Continental Institute of Public Health Addis Ababa Ethiopia

Diarrhea remains a major cause of mortality in children under 5 years of age in Sub-Saharan countries in Africa. Risk factors for diarrhea vary by context and have important implications for developing appropriate strategies to reduce the burden of the disease. The objective of this study was to assess the prevalence of diarrhea and associated risk factors among children un-der 5 years of age in Kersa district, located in Eastern Ethiopia. A community-based cross-sectional study was conducted among 1456 randomly selected households with at least one child under 5 years of age. A questionnaire and an observational check list were used for col-lecting information on socio-economic charac-teristics, environmental hygiene and behavioral practices, and occurrence of diarrhea among children under 5 years of age. Logistic regres-sion was used to calculate the adjusted odds ratio of 95% confidence interval. The two-week prevalence of diarrhea among children under 5 years of age was 22.5% (95% CI: 20.3-24.6). Improper refuse disposal practices (OR = 2.22, 95% CI: 1.20-4.03), lack of hand washing facilities (OR = 1.92, 95%CI: 1.29-2.86), living in rural area (OR = 1.81, 95% CI: 1.12-3.31), the presence of two or more siblings in a household (OR = 1.74, 95% CI: 1.33-2.28), and age of the child (OR= 2.25, 95% CI;1.5-3.36) were the major risk factors for diarrhea. This study demonstrated that diarrhea morbidity was relatively high among children under 5 years of age residing in Eastern Ethiopia. Efforts to reduce childhood diarrhea should focus on improving household sanitation, personal hygiene, and child birth spacing.

关键词： Diarrhea Risk Factor Children under 5 Years Ethiopia Cross-Sectional Study Hygiene

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具有1DPC反射层的微晶硅叠层太阳电池的吸收率优化研究

具有1DPC反射层的微晶硅叠层太阳电池的吸收率优化研究

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作者： Muluneh alemayehu Hailegiorgies 哈尔滨工业大学

学位级别：硕士

使用最薄的材料，最高效地吸收尽可能广范围波长的入射太阳光是可实际应用的硅基太阳电池的设计的一个基础问题。而由非晶硅（顶电池）和微晶硅（底电池）叠加构成的微晶硅叠层太阳电池是最具可行性的新型硅基薄膜电池之一。对于多结太... 详细信息

使用最薄的材料，最高效地吸收尽可能广范围波长的入射太阳光是可实际应用的硅基太阳电池的设计的一个基础问题。而由非晶硅（顶电池）和微晶硅（底电池）叠加构成的微晶硅叠层太阳电池是最具可行性的新型硅基薄膜电池之一。对于多结太阳电池来说，其短路电流（Jsc）由提供最小短路电流的子电池决定。由于当太阳光通过微晶硅叠层电池顶电池时，一部分光被顶电池吸收，剩余的光会通过底电池而最终被吸收。作为顶电池的非晶硅电池存在光致衰退效应，这就造成只能使用较薄的非晶硅作为顶电池，但这样的非晶硅厚度无法满足吸收长度的要求，双结电池的Jsc的限制通常来自于顶电池。而对于底电池，大于900nm的长波段光只有很少部分被底电池吸收。因此实现最佳的短路电流（Jsc）匹配是微晶硅叠层太阳电池领域的一大挑战。缓解这一问题的方法是陷光，利用一维光子晶体（1D Photonic crystal（1DPC））反射镜增强和增加长波长光子衍射和光学传播路径长度。我们设计整合了1DPC作为微晶硅叠层电池的中间反射镜及背反射镜，以此来研究光吸收增强效果。研究表明：通过对1DPC作为中间层和背反射层的适当设计，顶电池和底电池的吸收效率均得到了提高，1DPC中间层的吸收效率增强效果高于ZnO（氧化锌）中间层。简言之，本文致力于利用光学模拟计算（4.3b版COMSOLMultiphysics软件）得到提高微晶硅叠层太阳电池的光吸收效率的有效途径。通过改变顶电池与底电池吸收层的厚度，我们对吸收率、反射率及透过率进行了分析。以1DPC分别作为背反射层，并以ZnO（氧化锌）和1DPC分别作为中间反射层，与普通叠层电池进行了对比分析。最终，我们得到1DPC对提高光吸收效率的贡献明显优于ZnO。通过建立SiO/TiO2/a-Si/ZnO/uc-Si/1DPC叠层电池结构优化模型，与普通的a-Si/uc-Si叠层太阳电池对比，在优化后的电池中，光吸收效率：a-Si层的提高了26.59%，uc-Si层提高了3.89%。更进一步，我们建议使用三维光子晶体（3DPC）。我们相信通过对恰当设计3DPC作为底电池的背反射层，较长波长的太阳光可以被散射和吸收。

关键词：吸收效率微晶硅叠层电池氧化锌中间层一维光子晶体光学模型 COMSOL Multiphysics

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意大利蜜蜂工蜂胚胎到幼虫转化期分子机理的蛋白质组和磷酸化蛋白质组分析

意大利蜜蜂工蜂胚胎到幼虫转化期分子机理的蛋白质组和磷酸化蛋白...

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作者： alemayehu Gala Bayeta 中国农业科学院

学位级别：硕士

蜜蜂是一种重要的有益昆虫,其生长发育过程经历胚胎、幼虫、蛹及成虫4个发育展阶段。在蜜蜂的全变态发育过程中,胚胎末期到幼虫初期的转变是其生活史中极其关键的阶段之一,标志着蜜蜂早期发育的开始。蜜蜂从胚胎到幼虫的转化过程中,除... 详细信息

蜜蜂是一种重要的有益昆虫,其生长发育过程经历胚胎、幼虫、蛹及成虫4个发育展阶段。在蜜蜂的全变态发育过程中,胚胎末期到幼虫初期的转变是其生活史中极其关键的阶段之一,标志着蜜蜂早期发育的开始。蜜蜂从胚胎到幼虫的转化过程中,除了孵化和个体大小的改变外,在分子水平上必将伴随发生一些改变,这意味着在这个过程中存在着一系列复杂的生物化学调控来实现胚胎到幼虫的顺利转变。因此,为了深入了解胚胎到幼虫转化过程中的分子机制,本研究采用双向凝胶电泳和多荧光染色技术获得胚胎3日龄和幼虫1日龄的全蛋白质组和磷酸化蛋白质组图谱,并对差异蛋白进行功能鉴定、生物信息学分析和部分关键蛋白在基因水平的表达验证。结果发现,在胚胎中有65个与发育、碳水化合物和能量代谢、生物合成以及氨基酸代谢相关的蛋白质表达上调,表明胚胎形成过程中需要大量代谢能以满足活跃的胚胎发育的需要;而骨架类、蛋白折叠类、脂肪酸和氧化代谢类蛋白在幼虫中的表达水平显著高于胚胎期,以保障幼虫快速生长发育的需要。同时在这两个发育阶段鉴定出的34个差异表达的磷酸化蛋白质中,碳水化合物和能量代谢类、发育类、抗氧化类和氨基酸代谢类在胚胎中表达上调,表明它们在胚胎细胞分裂增殖和分化过程中发挥重要作用;而在幼虫中细胞骨架类、生物合成类磷酸化蛋白的高表达对新孵化的组织器官重塑具有重要作用。研究结果表明了蛋白质的磷酸化水平和蛋白质表达水平的变化对蜜蜂从胚胎到幼虫的早期发育起到关键的调控作用。从蛋白质水平上揭示的蜜蜂从胚胎到幼虫形态转化过程中的分子机制,不仅对深刻认识蜜蜂发育生物学具有重要意义,而且为利用反向遗传学手段研究蜜蜂优良生物学特性提供了理论基础。

关键词：意大利蜜蜂蛋白质组磷酸化蛋白质组工蜂胚胎幼虫孵化

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Mortality and Associated Risk Factors among In-Patients with Covid-19 in Douala, Cameroon: A Retrospective Cross-Sectional Study

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Advances in Infectious Diseases 2022年第1期12卷 1-19页

作者： Francois Adrien Bokalli Fru McWright Chi Ephesians Anutebeh Caven Ngoe Mbachan Takere Edwin Ewane Dieudonne Akanji Conrald Ekukole Marie-Solange Ndom Mireille-Laurent endale David Mekolo Henry Luma Jacqueline Ze Minkande Marcelin Ngowe Ngowe Specialised COVID-19 Treatment Centre Yassa Douala Cameroon Department of Medicine Faculty of Health Sciences University of Buea Buea Cameroon Department of Medicine Laquintinie Hospital Douala Cameroon Intensive Care and Emergency Department Laquintinie Hospital Douala Cameroon Department of Internal Medicine Douala General Hospital Douala Cameroon Department of Surgery and Specialties Faculty of Medicine and Biomedical Sciences University of Yaounde Yaounde Cameroon Department of Surgery and Specialties Faculty of Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon

Background: In March 2020, the World Health Organization declared the coronavirus disease 2019 a pandemic, this was caused by the Severe Acute Respiratory Syndrome Coronavirus 2. The overall mortality from this remains high, yet there are limited studies assessing the associated factors in Africa. Objective: To identify the factors associated with mortality in hospitalized COVID-19 patients in Douala, Cameroon. Method: We conducted a single-centre retrospective cross-sectional study by reviewing records of patients managed for COVID-19 between March and June 2020. Diagnosis was confirmed by real-time RT-PCR. Outcome of interest was mortality during hospitalization. We inputted and analyzed data using SPSS version 25.0, compared mortality between groups using the Chi’s squared test and the Fisher’s exact test where appropriately investigated for associations using the Logistic regression in a stepwise approach and alpha-value set at P = 0.05. Results: We analyzed 282 case files, 68% were males (M:F = 2:1) and a mean age of 52 (±15) years. We had an overall mortality of 31.5% (89/282 patients) and 54% (50/92 patients) admitted in the ICU died. Patients aged 0 - 39 years had a significantly lesser odds of mortality compared to those > 70 years (OR: 0.2 (0.1 - 0.5) P Conclusion: The in-hospital mortality in COVID-19 patients is very high and hospitalisation into the ICU is associated with even higher mortality. Advanced age, diffused lung involvement (particularly with alveolar consolidation), hemodynamic instability at presentation and altered level of consciousness favoured hospitalisation in the ICU. Once in the ICU, placement on mechanical ventilation did not reduce death discernibly.

关键词： COVID-19 Risk Factors Mortality Cameroon

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Chemical constituents,physicochemical properties and antibacterial activity of leaves essential oil of Ocimum urticifolium

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Journal of Coastal Life Medicine 2016年第12期4卷 955-960页

作者： Ketema alemayehu Mathewos Anza Destaw Engdaw Abedelfeta Mohammed Department of Chemistry College of Natural and Computational ScienceWolaita Sodo UniversityP.O.Box 138Wolaita SodoEthiopia

Objective:To determine chemical compositions,physicochemical properties and evaluating antibacterial activities of essential oils extracted from leaves of Ocimum urticifolium(***).Methods:Essential oil of *** was extracted by hydrodistillation technique.A number of phytochemical screening tests were applied to identify the classes of compounds in the leaves extract of *** chromatography and gas chromatography/mass spectrometry were used to characterize the chemical components in the essential *** agar diffusion method was used to evaluate the antibacterial activity as per of standard ***:Phytochemical screening of crude extract revealed that the presence of tannins,glycosides,saponins,flavonoids,steroids,terpenoids and *** obtained oil yield is(0.33±0.11)%(v/w).Analysis of oil using gas chromatography and gas chromatography/mass spectrometry showed a total of 22 components,the abundance of monoterpene and sesquiterpenes(98.99%).The percentage composition of monoterpene in the oil wasα-pinene(22.105%),eugenol(21.099%),while sesquiterpenesα-cubebene(11.341%),α-bisabolene(9.945%),α-caryophyllene(7.709%),α-caryophyllene oxide(5.754%),and copaene(3.594%).The oil inhibited the growth of Staphylococcus aureus and Escherichia coli,while no activity was shown to Salmonella ***:The *** is a rich source of various classes of chemical constituents and the antibacterial activity of the oil could be attributed mainly to these compounds.

关键词： Ocimum urticifolium Essential oil Antibacterial activity Chemical constituents

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Study on Front Passenger Injury in Front Crash under EURO-NCAP

Study on Front Passenger Injury in Front Crash under EURO-NC...

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作者： alemayehu Ashenafi Godifey 厦门理工学院

学位级别：硕士

With the change of social-economic structure of this world,female consciousness and social status,the number of women involved in the traffic accident increases every *** trends indicate that future female drivers may be equally as likely to be involved in a *** is necessary that motor vehicle safety systems provide equitable injury protection to occupants of either sex involved in moderate to serious *** to the relatively high exposure and fatal crash involvement rate,standard adult occupant safety systems have been designed and evaluated with a focus on the occupant characteristics typically representing the male *** should be noted that the effectiveness of such safety devices is sensitive to occupant age,anthropometric size,injury tolerance,and the mechanical response of the affected body *** sex is expected to be correlated with these variables（except age）,current advances in safety technology optimized for male characteristics may not be equally effective in protecting female ***,many international generally accepted passive safety assessment tests have added female dummy to be evaluation *** with those changes is the increasing concern of the Auto companies to the performance of passive safety ***,there are few studies of female occupant *** make up the above shortcomings,Hybrid III 5th female dummy was used for this *** main content of this dissertation is shown as following:（1）Multi-body models of frontal full width impact with Hybrid III 5th dummies seated in the driver position and front passenger position were established and validated based on the date and description of an impact test.A parametric study was performed to investigate the efficacy of restraint *** computation between parameters and models was achieved with MADYMO and MODEFRONTIER,and parametric sensitivity analysis was done.（2）Latin Hypercube Sampling was used to optimize the const

关键词： Front al crash Restraint system Female occupants

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