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镍钴纳米复合镀层在滨海盐土模拟溶液中的耐腐蚀性能

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材料热处理学报 2021年第2期42卷 130-138页

作者：姚亮康敏张银 samuel mbugua nyambura 南京农业大学工学院江苏南京210031 南京农业大学江苏省智能化农业装备重点试验室江苏南京210031

为了提高45钢在盐土环境中的耐腐蚀性能,采用电沉积法在其表面制备了Ni-Co-Si_(3)N_(4)、Ni-Co-Al_(2)O_(3)和Ni-Co-Si_(3)N_(4)-Al_(2)O_(3)纳米复合镀层。利用扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)对镀层的形貌、相结构和成... 详细信息

为了提高45钢在盐土环境中的耐腐蚀性能,采用电沉积法在其表面制备了Ni-Co-Si_(3)N_(4)、Ni-Co-Al_(2)O_(3)和Ni-Co-Si_(3)N_(4)-Al_(2)O_(3)纳米复合镀层。利用扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)对镀层的形貌、相结构和成分进行了表征和分析,并利用光学接触角测量仪和电化学工作站分别对镀层的润湿性及耐蚀性能进行了研究。结果表明:与Ni-Co-Si_(3)N_(4)和Ni-Co-Al_(2)O_(3)镀层相比,Ni-Co-Si_(3)N_(4)-Al_(2)O_(3)复合镀层表面晶粒相对细化,晶胞均匀致密,镀层平均晶粒尺寸最小,为19.20 nm;Ni-Co-Si_(3)N_(4)-Al_(2)O_(3)镀层表面静态接触角达到131.4°,表面疏水性最佳;电化学测试表明,在土壤模拟溶液条件下,Ni-Co-Si_(3)N_(4)-Al_(2)O_(3)镀层的自腐蚀电流密度和腐蚀速率分别为1.30μA·cm^(-2)和0.016 mm·a^(-1),电荷转移电阻为214.91 kΩ·cm^(-2),镀层具有更优的耐蚀性。

关键词：电沉积二元纳米复合镀层土壤模拟溶液疏水性耐蚀性

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Optimization of a three-row air-suction Brassica chinensis precision metering device based on CFD-DEM coupling simulation

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International Journal of Agricultural and Biological Engineering 2023年第3期16卷 130-142页

作者： Xinping Sun Hua Li Xindan Qi Dinghao Feng Jianqi Zhou Yongjian Wang samuel mbugua nyambura Xiaoyu Zhang Xi Chen College of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China Key Laboratory of Intelligent Agricultural Equipment in Jiangsu Province Nanjing Agricultural UniversityNanjing 210031China College of Engineering Nanjing Agricultural UniversityNanjing 210031China Jiangsu Xuzhou Transportation Planning and Design Institute Xuzhou 221000China

This study aimed to optimize a three-row air-suction Brassica chinensis precision metering device to improve the low seeding *** 17.0 Software was used to analyze the effect of different numbers of suction holes and different suction hole structures on the airflow *** was found that a suction hole number of 60 was beneficial to the flow field stability and a conical hole structure was beneficial to the adsorption of ***-Behnken design experiments were carried out with negative pressure,rotational speed,and hole diameter as the experimental *** optimal parameter combination was achieved when the negative pressure was 3.96 kPa,the rotational speed of the seeding plate was 1.49 rad/s and the hole diameter was 1.10 *** qualification rate of inner,middle,and outer rings were 87.580%,90.548%,and 90.117%,respectively,and the miss seeding rate of inner,middle,and outer rings were 10.915%,7.139%,and 5.920%,respectively.

关键词： Brassica chinensis metering device airflow field Box-Behnken design

电沉积Ni-W-Cr2O3纳米复合镀层的制备及其性能研究

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电沉积Ni-W-Cr2O3纳米复合镀层的制备及其性能研究

作者： samuel mbugua nyambura 南京农业大学

学位级别：硕士

45钢具有相对较好的机械性能,是工业上最常用的金属之一。但是,其使用不可避免地会受到腐蚀和磨损现象的影响,从而降低其效率甚至导致机械故障。表面改性技术可用于改善工业设备的表面性能并确保工业生产的可靠性。本课题主要研究Ni-W-C... 详细信息

45钢具有相对较好的机械性能,是工业上最常用的金属之一。但是,其使用不可避免地会受到腐蚀和磨损现象的影响,从而降低其效率甚至导致机械故障。表面改性技术可用于改善工业设备的表面性能并确保工业生产的可靠性。本课题主要研究Ni-W-Cr203纳米复合涂层的制备工艺参数与性能。试验通过电沉积装置进行Ni-W-Cr203纳米复合涂层的制备,分别使用扫描电镜、XRD衍射仪、能谱仪、激光共聚焦显微镜、显微硬度计、磨损仪和电化学工作站等对镀层的表面形貌、化学成分、物相结构、显微硬度、磨痕深度、表面粗糙度及耐腐蚀性等进行了表征,研究了不同电沉积加工工艺参数对镀层性能的影响规律。研究内容主要包含以下几方面:(1)W浓度和Cr2O3颗粒浓度的确定。选用Na2WO4·2H2O浓度分别为10g/L、20g/L、30g/L和40g/L,在相同工艺条件下制备Ni-W二元合金涂层,且对比不同W浓度下镀层的表面形貌、化学成分、物相结构、显微硬度、磨痕深度、表面粗糙度及耐腐蚀性,通过综合分析,确定最佳的W浓度为40g/L。在W浓度优化后制备的Ni-W二元合金涂层基础上,选用20nm的Cr2O3颗粒,浓度分别为0g/L、2g/L、6g/L、10g/L和20g/L,在相同工艺条件下进行试验,对比不同颗粒浓度下Ni-W-Cr2O3纳米复合涂层的显微硬度、磨痕深度、表面粗糙度及耐腐蚀性,通过综合分析,确定最佳的颗粒浓度为10g/L。(2)电沉积Ni-W-Cr2O3纳米复合涂层的基础试验研究。通过前期探索试验确定各工艺参数的取值范围,分别研究电流密度、电解液温度和搅拌速率对Ni-W-Cr203纳米复合涂层显微硬度、磨痕深度、表面粗糙度及耐腐蚀性的影响。通过试验结果可知,当电流密度为1A·dm-2、电解液温度为55℃、搅拌速率为350 rpm时,各工艺参数下制备的Ni-W-Cr203纳米复合涂层综合性能最佳。(3)基于Design Expert软件的电沉积Ni-W-Cr2O3纳米复合涂层工艺试验研究。在基础试验研究的基础上,进一步研究Cr2O3颗粒浓度、电流密度、电解液温度和搅拌速率的交互作用以及对镀层显微硬度、磨痕深度、表面粗糙度的影响规律。首先通过Design Expert定制设计进行试验设计,通过试验结果得出相对应的回归方程并进行多响应优化,通过三维曲面图与等高线图分析不同因子交互作用对镀层性能的影响大小。对三个回归方程进行多响应优化,得到预测的最佳工艺参数组合为:Cr2O3颗粒浓度10.19g·L-1,电流密度1.06A·dm-2,电解液温度56.16℃,搅拌速率343.67rpm。在此工艺条件下,镀层相关检测量预测值为:显微硬度610.49HV0.2,磨痕深度11.4μm,表面粗糙度0.28μm。试验结果与预测结果进行对比,误差较小,模型可靠性高。

关键词：电沉积 Ni-W-Cr2O3纳米复合镀层显微硬度耐磨性耐蚀性

基于STM32大蒜联合收获机监测系统设计与试验

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智能化农业装备学报(中英文) 2024年

作者：王永健丁想李骅 samuel mbugua nyambura 李玉青葛艳艳仇世龙冯学斌南京农业大学工学院江苏省智能化农业装备重点实验室

大蒜联合收获机已基本实现了大蒜的机械化收获，但其智能化水平较低，在作业过程中易发生偏航、溢仓及堵塞等问题，影响整机的作业质量和收获效率。针对这些问题，本研究设计了一套大蒜联合收获机的实时监测系统，能够实时、准确监测作... 详细信息

大蒜联合收获机已基本实现了大蒜的机械化收获，但其智能化水平较低，在作业过程中易发生偏航、溢仓及堵塞等问题，影响整机的作业质量和收获效率。针对这些问题，本研究设计了一套大蒜联合收获机的实时监测系统，能够实时、准确监测作业过程中的偏航、溢仓和堵塞故障问题，并进行语音播报提醒。该系统主要包括对行辅助模块、产量监测模块、故障诊断模块以及STM32单片机等。其中，对行辅助使用MPU6050陀螺仪监测收获机航向信息，与设定的航向角预警、报警阈值进行比较，判断收获机是否偏离正常作业路线；产量监测将单粒大蒜质量与统计的大蒜总数相乘计算出已收获的蒜头总质量，并与设定的满仓阈值进行比较，判断收集仓是否满仓；故障诊断通过霍尔传感器收集夹持输送机构从动轮的转速，并与设定阈值进行比较，判断是否发生堵塞。通过室内调试，对行辅助模块最大误差值为1.3°，最小误差值为0.2°；产量监测模块监测计数准确率为96.7%；故障诊断模块识别转速平均误差值为0.8 r/min，误差率为0.4%，能够准确监测夹持装置堵塞时从动轮转速的变化状况。田间试验结果表明设计的监测系统具备可行性、准确性和稳定性。通过该研究，本监测系统可以长时间稳定工作，并在大蒜收获机出现偏航、溢仓及堵塞故障时，及时发出报警信息，能够显著改善传统大蒜收获机的作业质量，提升作业效率。

关键词：大蒜收获机对行辅助实时监测阈值

Bacteriophages Isolated in China for the Control of Pectobacterium carotovorum Causing Potato Soft Rot in Kenya

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Virologica Sinica 2019年第3期34卷 287-294页

作者： Peter Muturi Junping Yu Alice nyambura Maina samuel Kariuki Frantis B.Mwaura Hongping Wei Key Laboratory of Emerging Pathogens and Biosafety Wuhan Institute of VirologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Centre for Microbiology Research Kenya Medical Research InstituteNairobi 00202Kenya School of Biological and Life Sciences Technical University of KenyaNairobi 00200Kenya School of Biological Sciences University of NairobiNairobi 00100Kenya Sino-Africa Joint Research Centre Nairobi 00200Kenya

Soft rot is an economically significant disease in potato and one of the major threats to sustainable potato *** study aimed at isolating lytic bacteriophages and evaluating methods for and the efficacy of applying phages to control potato soft rot caused by Pectobacterium *** bacteriophages isolated from soil and water samples collected in Wuhan,China,were used to infect *** host strains isolated from potato tubers showing soft rot symptoms in Nakuru county,*** efficacy of the phages in controlling soft rot disease was evaluated by applying individual phage strains or a phage cocktail on potato slices and tubers at different time points before or after inoculation with a *** *** phages could lyse 20 strains of ***,but not Pseudomonas fluorescens control *** the 11 phages,Pectobacterium phage Wc5r,interestingly showed cross-activity against Pectobacterium atrosepticum and two phage-resistant *** *** slice assays showed that the phage concentration and timing of application are crucial factors for effective soft rot *** cocktail applied at a concentration of 1×10^9 plaque-forming units per milliliter before or within an hour after bacterial inoculation on potato slices,resulted in>90%reduction of soft rot *** study provides a basis for the development and application of phages to reduce the impact of potato soft rot disease.

关键词： Pectobacterium carotovorum Potato soft rot Bacteriophages Phage resistance

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Ni-Co-P合金镀层显微硬度及其耐海水腐蚀性

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材料科学与工程学报 2021年第3期39卷 384-392页

作者：张银康敏李恒征刘运通金美付 nyambura samuel mbugua 南京农业大学工学院江苏南京210031 江苏省智能化农业装备重点试验室江苏南京210031

采用电沉积技术制备了Ni-Co-P合金镀层,并对镀层的表面形貌、晶相结构、显微硬度及耐腐蚀性进行了表征和分析。研究结果表明:Ni-Co-P合金镀层表面均匀平整,晶粒尺寸细小,显微硬度均优于Ni-P合金镀层;当镀液中CoSO_(4)·7H_(2)O含量为50... 详细信息

采用电沉积技术制备了Ni-Co-P合金镀层,并对镀层的表面形貌、晶相结构、显微硬度及耐腐蚀性进行了表征和分析。研究结果表明:Ni-Co-P合金镀层表面均匀平整,晶粒尺寸细小,显微硬度均优于Ni-P合金镀层;当镀液中CoSO_(4)·7H_(2)O含量为50g/L时,Ni-Co-P合金镀层的显微硬度达到766.3HV_(0.2)。在人工海水环境中,Ni-Co-P合金镀层的开路电位稳定值更正,腐蚀电流密度与腐蚀速度最小分别为0.68μA·cm^(-2)和8.25μm·year^(-1);且Ni-Co-P合金镀层的容抗弧半径均大于Ni-P合金镀层,电荷转移电阻(Rct)高达9.902×10^(4)Ω·cm^(-2),约为Ni-P合金镀层的6倍,表现出优异的耐海水腐蚀性能。

关键词：电沉积 Ni-Co-P合金镀层显微硬度耐海水腐蚀性

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Exploring perspectives on antimicrobial stewardship:a qualitative study of health managers in Kenya

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Global Health Research and Policy 2020年第1期5卷 67-75页

作者： samuel Mungai mbugua George Njoroge Caroline Kijogi Moses Kamita Rachel Kimani Peter Mwaura Bibianne Waiganjo Aidi Jesse Gitaka Mount Kenya University ThikaKenya

Background:Antimicrobial resistance is a significant public health concern with the establishment of antimicrobial stewardship in hospitals being increasingly *** and insights of health managers on antimicrobial stewardship(AMS),complementary health services and building blocks are imperative towards implementation of robust AMS *** study aimed to understand perspectives of hospital managers on AMS and identify areas of management engagement while addressing potential blockades to ***:A cross-sectional,qualitative,multicenter study was conducted in three hospitals in ***-informant interviews on perspectives on AMS were administered to hospital *** data was captured using audio tapes and field notes,transcribed and managed using NVivo 12 *** iterative process was used to develop the thematic framework and updated in two rounds of iteration *** charts for each emergent theme were developed and categorized across all ***:Perspectives on AMS are described in five thematic categories;Importance of antimicrobial stewardship and the role of medicines and therapeutics committee,availability of antimicrobial formulary and usage surveillance systems,laboratory competency and recommendations for infection prevention and management,educational resources and communications channels available,building blocks and low-lying fruits for Antimicrobial Stewardship *** role of stewardship collaboration in diagnosis and antimicrobial prescription was alluded to with managers indicating a growing rise in occurrence of antimicrobial *** lacked contextualized,hospital specific antimicrobial formulary and adequate laboratory *** training and communication channels were available in varying capacity across the three *** blocks identified include medicines and therapeutics committee,education,and training platforms(Continuous Medical Educati

关键词： Antimicrobial stewardship Antimicrobial resistance Building blocks/low-lying fruits

Nutrition Status of Children Under-Five Years in Cassava Consuming Communities in Nambale, Busia of Western Kenya

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Food and Nutrition Sciences 2012年第6期3卷 796-801页

作者： Rhoda Azikoyo Nungo Michael Wandayi Okoth samuel Kuria mbugua Department of Food Science Nutrition and Technology University of Nairobi Nairobi Kenya.

A study was carried out to assess the nutritional status of under-five child population within cassava consuming community in Nambale of western Kenya. A structured questionnaire was used to collect socio economic data, 24-hour food re-call and anthropometric measurements. Data were analyzed using Statistical Package for Social Sciences. Descriptive statistics were used while Pearson’s Chi Square and correlation coefficient (R) were used to test for statistical associations. A total of 320 households with 232 children participated. The findings showed nutrition status of children to be poor (50% changes in stunting could not be attributed to age of child or education level of the head of household. Farm ownership was a strong positive determinant of nutrition status, Pearson’s R = 0.233. This study has established that cassava cushions hunger and there is need to improve nutrient content.

关键词： Cassava Children Nutritional Status Utilization