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Galvanic and asymmetry effects on the local electrochemical behavior of the 2098-T351 alloy welded by friction stir welding

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Journal of Materials Science & Technology 2020年第10期42卷 162-175页

作者： Mariana X.Milagre uyime donatus Naga V.Mogili Rejane Maria PSilva Barbara Victoria Gde Viveiros Victor F.Pereira Renato A.Antunes Caruline S.CMachado Joao Victor S.Araujo Isolda Costa Instituto de Pesquisas Energeticas e Nucleares IPEN/CNENAv.Prof.Lineu Prestes2242Sao PauloBrazil Laboratorio Nacional de Nanotecnologia LNNano/CNPENRua Giuseppe Maximo Scolfaro10.000Polo II deAlta Tecnologia de CampinasBrazil Centro de Engenharia Modelagem e Ciencias Sociais AplicadasUFABCAv.dos Estados 5001Santo AndreBrazil

Scanning electrochemical microscopy(SECM)and scanning vibrating electrode technique(SVET)were used to investigate the electrochemical behaviour of the top surface of the 2098-T351 alloy welded by friction stir welding(FSW).The SVET technique was efficient in identifying the cathodic and anodic weld regions.The welding joint(WJ),which comprises the thermomechanically affected zone(TMAZ)and the stir zone(SZ),was cathodic relative to the heated affected zone(HAZ)and the base metal(BM).The reactivities of the welding joint at the advancing side(AS)and the retreating side(RS)were analyzed and compared using SECM technique in the competition mode by monitoring the dissolved oxygen as a redox mediator in 0.005 mol L^-1 NaCl solution.The RS was more electrochemically active than the AS,and these results were correlated with the microstructural features of the welded alloy.

关键词： Aluminum alloys Friction stir welding Localized corrosion

A Comparative Survey of an Approximate Solution Method for Stochastic Delay Differential Equations

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Applied Mathematics 2023年第3期14卷 196-207页

作者： Emenonye Christian Emenonye donatus Anonwa Mathematics Department University of Delta Agbor Nigeria Mathematics Department Delta State University Abraka Nigeria

This study is focused on the approximate solution for the class of stochastic delay differential equations. The techniques applied involve the use of Caratheodory and Euler Maruyama procedures which approximated to stochastic delay differential equations. Based on the Caratheodory approximate procedure, it was proved that stochastic delay differential equations have unique solution and established that the Caratheodory approximate solution converges to the unique solution of stochastic delay differential equations under the Cauchy sequence and initial condition. This Caratheodory approximate procedure and Euler method both converge at the same rate. This is achieved by replacing the present state with past state. The existence and uniqueness of an approximate solution of the stochastic delay differential equation were shown and the approximate solution to the unique solution was also shown. .

关键词： Approximate Solution Differential Equations Techniques Stochastic Differential Equation Existence Uniqueness Approximate Procedure

CD4⁺ T-Cell Count, Serum Zinc, Copper and Selenium Levels in HIV Sero-Positive Subjects on ART and ART Naïve Subjects in Port Harcourt, Nigeria

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Journal of Biosciences and Medicines 2022年第5期10卷 105-116页

作者： donatus Onukwufor Onwuli Helen Waribo-Anthony Okwuchi Eberechukwu Anyalebechi Chioma Ugochukwu River State University Nkpolu Oroworukwo Port Harcourt Nigeria Rivers State University Teaching Hospital Port Harcourt Nigeria

Background: HIV infection results in depletion of immunocompetent cells such as CD4+ T-cells. Trace elements such as Copper, Zinc and selenium are known to be involved in immune function. In recent times, HIV-positive patients are treated with antiretroviral therapy (ART), with significant progress. This study was aimed at evaluating CD4+ T-cells levels, serum Copper, Zinc and Selenium levels in HIV seropositive subjects on ART and ART naive subjects (HIV positive subjects that have not started ART treatment) in Rivers State, Nigeria. Methods: 150 subjects aged 20 to 79 years were recruited after informed consent. 70 subjects were HIV-positive on ART, 30 subjects were HIV-positive ART naïve subjects, while 50 subjects were apparently healthy subjects. Ten (10) milliliters of blood was collected using a standard venipuncture technique from each subject for the analysis of CD4 T-cells using BD fluorescent activated cell sorter (FACSC count), serum Copper and Zinc were analyzed colorimetrically using semi auto-analyzer WP 21E, while selenium was analyzed using atomic absorption spectrophotometer ELICO, SL173. Data generated were analyzed using Graph-Pad Prism version 8.0.2 and p Result: This study revealed a significant reduction in mean zinc, selenium and CD4+ T-cell level respectively (p = 0.0006;0.0001;0.0001) in HIV-Positive subjects on ART and ART naive. There was also a significant increase in mean serum copper level in the HIV-positive subject as compared to control subjects (p = 0.0001). ART treatment improved the CD4+ T cell count and serum levels of selenium and zinc;however, ART did not correct the imbalance. Furthermore, female subjects on ART have a significantly higher CD4+ T-cell count than the males (p Conclusion: Selenium and Zinc deficiency are associated with HIV disease despite the role of ART hence micronutrient supplementation is advised for HIV-positive subjects on ART.

关键词： Anti Retroviral Therapy (ART) Human Immunodeficiency Virus (HIV) Trace Elements CD4 T-Cells

Evaluation of Plasma Homocysteine Levels in Type II Diabetes and Hypertensive Patients Attending University of Port Harcourt Teaching Hospital, Nigeria

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Journal of Biosciences and Medicines 2023年第5期11卷 30-39页

作者： donatus Onukwufor Onwuli Helen Anthony Waribo Eberechkwu Okwuchi Anyalebechi Loveth Ukamaka Nwafor Chemical Pathology Unit Department of Medical Laboratory Science Rivers State University Port Harcourt Nigeria

Background: Homocysteine is an important non-protein amino acid, very useful in all methylation reactions occurring in the body as the precursor of the sole methyl group donor S-Adenosyl-methionine (SAM). However, elevated plasma homocysteine levels have been reported to contribute to epithelial damage leading to coronary artery disease and other metabolic syndromes. This study was aimed at evaluating the concentration of plasma homocysteine in diabetics and hypertensive patients in Port Harcourt, Nigeria. Methods: The study population included 60 Type II diabetes mellitus and Hypertensivesubjectsas group (I), 60 Type II diabetes mellitus and Normotensive subjects as group (II), 60 Hypertensive subjects as group (III), and 60 healthy subjects as control group within the age range of 30 - 70 years. An enzyme-linked immunosorbent assay (ELISA) method was used to quantitatively measure homocysteine in the serum sample, glycated haemoglobin were determined quantitatively using sandwich immunodetection and blood pressure was determined using mercury sphygnanometer. Statistics: The statistical analysis was done using GraphPad Prism version 9.4.1, and statistical significance was determined by a P Results: The results showed significantly higher plasma homocysteine levels in diabetics and hypertensive comorbidity patients when compared to healthy controls, P Conclusion: Our result shows an increase in plasma homocysteine levels in diabetics and hypertensives when compared to controls, and comorbidity instigates a higher increase in plasma levels when compared with the single morbidity.

关键词： Hypertensives Diabetes Mellitus Homocysteine Hyperhomocysteinemia

Assessment of Nephro-, Hepato-, and Sex-Dependent Toxicity of Carmoisine Exposure in Albino Rats

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Journal of Biosciences and Medicines 2023年第9期11卷 63-78页

作者： Ibioku Elekima Uchechukwu Achor Obisike Holy Brown Helen Anthony Waribo Ngozi Brisibe Ibitoroko George-Opuda Adline Ben-Chioma donatus Onwuli Chemical Pathology Unit Department of Medical Laboratory Science Rivers State University Port Harcourt Nigeria Medical Diagnostics Cranfield School of Health Cranfield University Bedford UK

Aim: To evaluate chronic exposure of carmoisine at ADI doses on some hepatocellular and renal parameters of male and female albino rats as well as to determine sex-dependent toxicity. Study Design: The study involves treatment for 30, 60, and 90 days. Each phase consists of 40 rats, divided into treatment and control groups. The treated groups were orally administered with 4.0 mg/kg of carmoisine daily for the periods of 30, 60, and 90 days. Methodology: At the end of the treatment, the rats were allowed to fast for 18 hours followed by the collection of 5 ml of whole blood specimens by means of cardiac puncture into Lithium Heparin bottles and fluoride oxalate bottles (for glucose only). Plasma obtained was analyzed for glucose (GLU), AST, ALT, ALP, creatinine (CRT), and urea. Hepatic and Renal tissues collected were fixed in 10% formol saline and later examined histologically using H&E stain. Statistical data analysis was done using GraphPad Prism version 9.02. Results: Glucose indicated significant increases after 30, 60, and 90 days of chronic treatment at ADI doses. Urea, Creatinine, AST, ALT and ALP showed significantly higher values after 60 and 90 days of treatment (except creatinine in male rats and ALP in female rats after 60 and 90 days respectively). Hepatic distortions, vacuolation, compression of central vein were seen in the liver section while distortion of proximal and distal tubules, and inflammation of the glomerulus were observed in the renal tissue of the treated rats. Conclusion: The administration of camoisine over a period of 30 days at ADI dose did not indicate hepatocellullar and renal derangements as well histological distortions in liver, and kidneys. However, after 60 and 90 days, mild hepatocellular, and renal derangements were seen. No sex-dependent toxicity was observed.

关键词： Carmoisine Toxicity Liver Enzymes Renal Tissue Sex-Dependent Azo Dye Creatinine Urea

A Modified Averaging Composite Implicit Iteration Process for Common Fixed Points of a Finite Family of k-Strictly Asymptotically Pseudocontractive Mappings

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Advances in Pure Mathematics 2011年第4期1卷 204-209页

作者： donatus Igbokwe Oku Ini Department of Mathematics University of Uyo Uyo-Nigeria

The composite implicit iteration process introduced by Su and Li [J. Math. Anal. Appl. 320 (2006) 882-891] is modified. A strong convergence theorem for approximation of common fixed points of finite family of k-stric... 详细信息

关键词： Implicit Iteration Process k-Strictly Asymptotically Pseudo-Contractive Maps Fixed Points

The gender pay gap： Review and update

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Chinese Business Review 2010年第6期9卷 51-58页

作者： donatus I. Amaram School of Business Virginia State University Petersburg VA 23806 USA

Design of a Hybrid Wind-Solar Energy System for an Agro-industrial Residential Area in Bota-Limbe, Cameroon

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Journal of Energy and Power Engineering 2019年第6期13卷 240-248页

作者： Chu donatus Iweh Lemundem Marius Department of Electrical and Electronic Engineering University of Buea Buea 63 Cameroon

This paper proposes the most feasible technical and environmentally friendly hybrid power system configuration;a stand-alone hybrid wind-solar energy system with battery storage for a residential area of an Agro-industrial Company, Cameroon Development Cooperation (CDC), with headquarters in Bota-Limbe, south west region, Cameroon. The power network of the CDC Bota-Limbe Camp amongst other camps, which accommodates plantation workers, is plagued with challenges such as reliance on grid power which is unreliable, poor power quality which endangers home appliances and a spider webbed transmission system that poses as a threat to the lives of plantation workers. This paper addresses those concerns by designing a modular hybrid solar-wind renewable energy system for the camp. Limbe is a coastal area with proven existence of wind and solar resources. It is expected that the proposed system, if adopted and well implemented, will provide huge opportunities for the CDC in several other locations in Cameroon where there is adequate supply of renewable energy resources.

关键词： Hybrid power system solar wind renewable energy resources Agro-industrial Company

尼日利亚大学生汉语学习需求调查研究——以纳姆迪·阿齐克韦大学孔子学院汉语学习者为例

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尼日利亚大学生汉语学习需求调查研究——以纳姆迪·阿齐克韦大学...

作者： donatus Obinna 厦门大学

学位级别：硕士

近年来中非合作的增加激起了非洲人对中国语言文化的兴趣,从而促进了非洲大陆汉语教学的发展。多年来,尼日利亚汉语教学已经取得了许多里程碑式的成果,但是,仍然需要面对一些挑战。2008年建立的纳姆迪·阿齐克韦大学孔子学院见证了汉语... 详细信息

近年来中非合作的增加激起了非洲人对中国语言文化的兴趣,从而促进了非洲大陆汉语教学的发展。多年来,尼日利亚汉语教学已经取得了许多里程碑式的成果,但是,仍然需要面对一些挑战。2008年建立的纳姆迪·阿齐克韦大学孔子学院见证了汉语学习者数量的快速增长,但汉语教学的一些瓶颈仍然存在。本研究以需求分析理论为研究基础,通过问卷调查来分析纳姆迪·阿齐克韦大学孔子学院学生所面临的主要问题。数据是通过半结构式问卷调查和采访收集得到的,并采用Google统计分析工具用于分析已有数据。此外,该研究还分析了可能影响学生学习的其他方面,如理想的上课时间、每班期望的学生人数等。调查结果表明,学生学习汉语的动机各有不同;最重要的动机是找工作。此外调查还发现,学生对口语和听力技能的要求高于语法、阅读、写作和词汇能力。通过调查分析,本人建议学校和教师应定期对学习者进行需求分析,并根据学习者的需求来更新调整课程设置。

关键词：纳姆迪·阿齐克韦大学孔子学院需求分析汉语学习者