检索结果-南通市图书馆

pH-Dependence of Manganese (II) Oxidation Reaction by Novel Wild-Type and Mutants Recombinant Phlebia radiata Manganese Peroxidase 3 (rPr-MnP3) Enzymes

引用

American Journal of Molecular Biology 2022年第2期12卷 67-84页

作者： Usenobong F. Ufot Monday I. Akpanabiatu Khasim Cali Ifiok D. Uffia inyang udosen Department of Genetics and Biotechnology Faculty of Biological Sciences Akwa Ibom State University Uyo Akwa Ibom State Nigeria Department of Biochemistry Faculty of Sciences University of Uyo Akwa Ibom State Uyo Akwa Ibom State Nigeria Department of Chemical Engineering and Analytical Science University of Manchester Manchester UK

The goal of this study was to determine whether mutation of the Mn-binding site of wild-type recombinant Phlebia radiata manganese peroxidase 3 affected the pH-dependence kinetic parameters. pH range investigated was 2.5 – 12.0. The catalytic efficiency of the mutant enzymes at high and low pH in comparison to the wild-type was investigated using standard rPr-MnP3 protocol. Wild-type recombinant Phlebia radiata MnP3 enzyme showed optimal activity with Mn (II) as substrate at pH 5.0 and remained moderately active (approximately 40%) in the pH range of 6.0 - 9.0. The rPr-MnP3 mutants’ maximum activity ranged between 5.5 and 8.0. Wild-type and mutants rPr-MnP3 enzymes exhibited a similar pH profile with optimum pH of 3.0 for ABTS oxidation. Mutation has severely decreased the catalytic efficiency for Mn (II) oxidation at pH 5.0. The rPr-MnP3 enzymes showed enhanced affinity for Mn (II) at alkaline pH and a more alkaline range for catalysis than ever reported for any Manganese Peroxidase. This study reveals that at higher pH, rPr-MnP3 can function with alternative ligands in the Mn (II) site and does not have an absolutely obligate requirement for an all carboxylate ligand set. These results further strongly confirm that Mn2+ binding site is the only productive catalytic site for Mn (II) oxidation.

关键词： pH-Dependence Phlebia radiata Manganese Peroxidase Wild-Type Mutants Recombinant Enzyme

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Investigation on microstructure evolution of clayey soils: A review focusing on wetting/drying process

引用

Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 269-284页

作者： Chao-Sheng Tang Qing Cheng Xuepeng Gong Bin Shi Hilary I.inyang School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China Global Education and Infrastructure Services Inc. CharlotteUSA

Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical behavior.In this review paper,methods that are commonly used to study soil microstructure are summarized.Among them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)technology.Moreover,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several decades.Soils compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal PSD.During drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate pores.During wetting,both the intra-and inter-aggregate pores increase gradually in number and sizes.Changes in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to wetting.During wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from macro-pores.Furthermore,based on this analysis and identified research needs,some important areas of research focus are proposed for future work.These areas include innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.

关键词： Soil microstructure Pore size distribution(PSD) Wetting/drying cycle Suction Volume change

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Soil micro-penetration resistance as an index of its infiltration processes during rainfall

引用

Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1580-1587页

作者： Chao-Sheng Tang Xue-Peng Gong Zhengtao Shen Qing Cheng Hilary inyang Chao Lv Bin Shi School of Earth Sciences and Engineering Nanjing University163 Xianlin AvenueNanjing210023China Global Institute for Sustainable Development CharlotteNCUSA

Rainfall infiltration is one of the most important driving factors of geological hazards, ecological environment problems, and engineering accidents. Understanding the principle of soil wetting during rainfall infiltration and its influence on soil mechanical properties is crucial for preventing geological hazards. In this study, micro-penetration tests coupled with moisture monitoring were performed to investigate the infiltration process during wetting through the measured change in mechanical characteristics. Results show that penetration resistance increases in the deep layer gradually. With increasing infiltration time,the wetting front keeps moving downward, and its range becomes wider. A slight increase of the penetration resistance in the shallow layer(d ≤ 17.5 mm) is observed. However, the penetration resistance in the middle layer(22.5 mm ≤ d ≤ 32.5 mm) decreases firstly before a slight increase. In the deep layer(d ≥ 37.5 mm), the penetration resistance decreases continuously during infiltration. Based on the measured water content profile during infiltration, it is found that the evolution of soil mechanical characteristics is fully responsible by the infiltration-induced re-distribution of water content along depth. Generally, the penetration resistance decreases exponentially with increasing water content in the soil. When the water content is low, wetting can weaken soil strength significantly, whereas this effect diminishes when the moisture surpasses a certain threshold. The results highlight that the penetration curves and water content profile show close inter-dependency and consistency, which verifies the feasibility of using micro-penetration to investigate rainfall infiltration and wetting process in surface soil layer or laboratory small-scale soil samples. This method enables fast, versatile and high-resolution measurements of infiltration process and moisture distribution in soil.

关键词： Micro-penetration test Soil wetting Rainfall infiltration Water content Hydro-mechanical behavior Microstructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Heat Transfer in Helical Coil Heat Exchanger

引用

Advances in Chemical Engineering and Science 2022年第1期12卷 26-39页

作者： Uwem Ekwere inyang Iniubong James Uwa Department of Chemical and Petroleum Engineering Faculty of Engineering University of Uyo Uyo Nigeria

The research paper tends to review the effectiveness of helical coil in heat exchangers (HCHE). Heat exchanger is a device used in transferring thermal energy between two or more fluids or solid interfaces and a fluid, in solid particulates and a fluid at different temperatures and thermal contact. The author has concisely discussed the helical coil in heat exchanger at different shapes and conditions and compared the HCHE with straight tubes heat exchangers, and the factors affecting the performance and effectiveness of the helical coil heat exchanger such as the curvature ratio, and other heat exchangers. The author demonstrated that the HCHE provided more excellent heat transfer performance and effectiveness than straight tubes and other heat exchangers because of secondary flow development inside the helical tube, and heat transfer coefficient increased with an increase in the curvature ratio of HCHE for the same flow rates. The secondary flow and mass flow rates, advantages and disadvantages have also been reviewed. The authors back their findings with available theories. Suitable fluid should be searched for high efficiency in the helical coil.

关键词： Helical Coil Heat Transfer Heat Exchanger Boundary Conditions Temperature

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

广东沿海红树林区水质变化特征与富营养状态评估

引用

热带海洋学报 2022年第6期41卷 1-11页

作者： inyang Aniefiok Ini 周月月王友绍热带海洋环境国家重点实验室(中国科学院南海海洋研究所) 广东广州510301 中国科学院大亚湾海洋生物综合试验站广东深圳518121 中国科学院南海生态环境工程创新研究院广东广州510301 中国科学院大学北京100049 南方海洋科学与工程广东省实验室(广州) 广东广州511458

调查了广东红树林区水质的时空变化,分别采集了红树林区表层水体水样旱季30个样点(2017年10月至2018年1月)和湿季20个样点(2018年7月至8月)进行分析。利用单一营养状态指数(TSI Chl a)评价红树林水质特征和营养状态,评价标准:0050为富营... 详细信息

调查了广东红树林区水质的时空变化,分别采集了红树林区表层水体水样旱季30个样点(2017年10月至2018年1月)和湿季20个样点(2018年7月至8月)进行分析。利用单一营养状态指数(TSI Chl a)评价红树林水质特征和营养状态,评价标准:0050为富营养,>70为高营养。红树林区环境参数的时空变化为:盐度(2.15‰~27.14‰)、p H(6.18~8.65)、电导率(10.87~90.52μs·cm)、浊度(0.0975~21.61FTU)、硝酸盐(0~127.2mg·L^(-1))、亚硝酸盐(0~12.0mg·L^(-1))、磷酸盐(0~34.5mg·L^(-1))、硅酸盐(1.22~2.88mg·L^(-1))和叶绿素a(0.19~38.08mg·m)。聚类分析表明,丰水期横跨雷州半岛右侧至广东沿海东部的水质相对较好,而左侧则处于中营养化状态。同时,在枯水期,红树林区水质较差,从雷州半岛周围的高中营养化状态,到广东沿海东部的富营养化状态。主成分分析表明,营养盐、盐度、p H、电导率(electrical conductivity,EC)和浊度对红树林区水质状况贡献显著,进而影响红树林生态系统中藻类群落的变化。

关键词：藻类丰度营养盐红树林营养状态广东沿海

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Environmental issues from coal mining and their solutions

引用

Mining Science and Technology 2010年第2期20卷 215-223页

作者： BIAN, Zhengfu inyang, Hilary I DANIELS, John L OTTO, Frank STRUTHERS, Sue institute of land resources china university of mining & technologyxuzhou 221008china global institute for energy and environmental systems university of north carolinacharlotte nc 28223usa global institute for energy and environmental systems university of north carolinacharlotte nc 28223usa natural science foundation of the usa arlington va 22230usa department of geoengineering and mining university of applied sciencebochum 44801germany skapa mining services orkney kw172sxuk

The environmental challenges from coal mining include coal mine accidents,land subsidence,damage to the water environment,mining waste disposal and air pollution.These are either environmental pollution or landscape change.A conceptual framework for solving mine environmental issues is proposed.Clean processes,or remediation measures,are designed to address environmental pollution.Restoration measures are proposed to handle landscape change.The total methane drainage from 56 Chinese high methane concentration coal mines is about 101.94 million cubic meters.Of this methane,19.32 million,35.58 million and 6.97 million cubic meters are utilized for electricity generation,civil fuel supplies and other industrial purposes,respectively.About 39% of the methane is emitted into the atmosphere.The production of coal mining wastes can be decreased 10% by reuse of mining wastes as underground fills,or by using the waste as fuel for power plants or for raw material to make bricks or other infrastructure materials.The proper use of mined land must be decided in terms of local physical and socio-economical conditions.In European countries more than 50% of previously mined lands are reclaimed as forest or grass lands.However,in China more than 70% of the mined lands are reclaimed for agricultural purposes because the large population and a shortage of farmlands make this necessary.Reconstruction of rural communities or native residential improvement is one environmental problem arising from mining.We suggest two ways to reconstruct a farmer's house in China.

关键词： mine environment management of mining wastes reuse of mine gas mined land reclamation clean coal mining

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Seropositivity of Chlamydophila pneumoniae immunoglobulin G antibody of HIV/AIDS patients in Abuja,Nigeria

引用

Asian Pacific Journal of Tropical Medicine 2010年第8期3卷 666-668页

作者： Yakubu Boyi Ngwai Izebe KS Ijele IG Ishaleku D inyang US Microbiology Unit Nasarawa State UniversityP.M.B.1022KeffiNasarawa StateNigeria National Institute for Pharmaceutical Research and Development P.M.B.21 GarkiAbujaNigeria

Objective:To detect IgG antibody to Chlamydophila pneumoniae(CP) in sera of HIV/AIDS patients and provide rationale for inclusion of routine screening for anti-CP antibodies and anti-chlamydial agents in the Nigerian National H1V/AIDS Management Plan.Methods:Serum samples from 34 consenting HIV/AIDS patients attended a Government-approved Antiretroviral Treatment Facility in Abuja were screened by enzyme-linked immunosorbent assay for anti-CP IgG antibody using ImmunoComb? Chlamydia Bivalent IgG Test kit(Orgenics,Israel).Results: Anti-CP IgG antibody was detected in 20(58.8%) of 34 patients tested.The detection rale was higher among the males(8/13:61.5%) than the females(12/21:57.1%).Patients of the age group 16-30 years had the highest(7/10:70%) detection of anti-CP IgG antibody.Conclusions:The result of the present study suggests the presence of anti-CP antibodies in sera of the HIV/AIDS patients,and reinforces the need for routine screening for anti-CP antibodies as a necessary intervention to reduce the burden of Chlamydophila pneumoniae(C.pneumoniae) infections and to reduce HIV-positive morbidity in Nigeria.The outcome of this study also provides justification for the possible inclusion of anti-chlamydial agents in the National HIV/AIDS Management Plan to provide prophylaxis against or treat active C.pneumoniae infections.

关键词： Chlamydophila pneumoniae Chlamydia Antibodies AIDS Nigeria

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modeling Rainfall Intensity-Duration-Frequency (IDF) and Establishing Climate Change Existence in Uyo-Nigeria Using Non-Stationary Approach

引用

Journal of Water Resource and Protection 2023年第5期15卷 194-214页

作者： Masi G. Sam Ify L. Nwaogazie Chiedozie Ikebude Ubong J. inyang Jonathan O. Irokwe Department of Civil and Environmental Engineering University of Port Harcourt Port Harcourt Nigeria Center for Occupational Health Safety & Environment University of Port Harcourt Port Harcourt Nigeria

This study aims at establishing if climate change exists in the Niger Delta environment using non-stationary rainfall Intensity-Duration-Frequency (IDF) modelling incorporating time-variant parameters. To compute the intensity levels, the open-access R-studio software was used based on the General Extreme Value (GEV) distribution function. Among the four linear parameter models adopted for integrating time as a covariate, the fourth linear model incorporating scale and location with the shape function constant produced the least corrected Akaike Information Criteria (AICc), varying between 306.191 to 101.497 for 15 and 1440 minutes, respectively, selected for calibration of the GEV distribution equation. The non-stationary intensities yielded higher values above those of stationary models, proving that the assumption of stationary IDF models underestimated extreme events. The difference of 13.71 mm/hr (22.71%) to 14.26 mm/hr (17.0%) intensities implies an underestimation of the peak flood from a stationary IDF curve. The statistical difference at a 95% confidence level between stationary and non-stationary models was significant, confirming evidence of climatic change influenced by time-variant parameters. Consequently, emphasis should be on applying shorter-duration storms for design purposes occurring with higher intensities to help reduce the flood risk and resultant infrastructural failures.

关键词： Precipitation Annual Maximum Series Stationary Non-Stationary Intensity-Duration-Frequency Models Trends

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Risk Assessment of Human Exposure to 2-Methylnaphthalene, Phenanthrene and Didodecylphthalate via Consumption of Shrimps (Macrobrachium vollenhovenii) from Qua Iboe River Estuary, South-South Nigeria

引用

Journal of Geoscience and Environment Protection 2023年第6期11卷 125-144页

作者： inyang O. Oyo-Ita Bassey B. Asuquo Emmanuella E. Oyo-Ita Orok E. Oyo-Ita Department of Pure & Applied Chemistry Environmental/Organic Chemistry Group University of Calabar Calabar Nigeria Department of Biochemistry Cross River University of Technology Calabar Nigeria

Ibeno, one of the major oil producing communities in South-South Nigeria is a coastal commercial fishery hub that houses Axon-Mobil operational base and pharmaceutical/plastic industries. Shrimp species (Macrobrachium vollenhovenii) is a major aquatic food frequently consumed by inhabitants of the coastal area and those living hinterland, thus, being a major route of human exposure to 2-methylnaphthalene, phenanthrene and didodecyl phthalate in the area. The purpose of the study was to evaluate factors that determine bioaccumulation and assess the potential cancer and non-cancer risk posed by these contaminants through human (adult and children) exposure via shrimp’s consumption using gas chromatography-mass spectroscopy. The associated sediment showed higher mean concentrations of 2-methylnaphthalene, phenanthrene and didodecylphthalate at the two sites relative to those in fresh shrimp samples and factors such as size, lipid content, physicochemical property and environmental condition influenced the uptake of these contaminants. Besides water loss, the traditional drying process enhanced the levels of phenanthrene and didodecylphthalate in dry shrimps most likely due to combustion process and relatively low volatility, respectively and lowered the level of 2-methylnapthalene linked to its relatively high volatility. The potential of cancer and non-cancer development in human were highest via dry large shrimp consumption and followed the sequence: dry small shrimp > fresh large shrimp > fresh small shrimp and were within the USEPA reference standards. Although children were more vulnerable, the exposed individuals may not exhibit notable health-associated adverse effects in the near future. Thus, adequate advocacy is needed to sensitize those living in the catchments who often prefer dry shrimp in their meals on the adverse health implications of these contaminants for their survival and the need to maintain the health of the ecosystem.

关键词： Bioaccumulation Human Exposure Toxicity Potential Shrimp

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Comparative Analysis of Climatic Change Trend and Change-Point Analysis for Long-Term Daily Rainfall Annual Maximum Time Series Data in Four Gauging Stations in Niger Delta

引用

Open Journal of Modern Hydrology 2023年第4期13卷 229-245页

作者： Masi G. Sam Ify L. Nwaogazie Chiedozie Ikebude Jonathan O. Irokwe Diaa W. El Hourani Ubong J. inyang Bright Worlu Department of Civil and Environmental Engineering University of Port Harcourt Port Harcourt Nigeria Center for Occupational Health Safety and Environment University of Port Harcourt Port Harcourt Nigeria

The aim of this study is to establish the prevailing conditions of changing climatic trends and change point dates in four selected meteorological stations of Uyo, Benin, Port Harcourt, and Warri in the Niger Delta region of Nigeria. Using daily or 24-hourly annual maximum series (AMS) data with the Indian Meteorological Department (IMD) and the modified Chowdury Indian Meteorological Department (MCIMD) models were adopted to downscale the time series data. Mann-Kendall (MK) trend and Sen’s Slope Estimator (SSE) test showed a statistically significant trend for Uyo and Benin, while Port Harcourt and Warri showed mild trends. The Sen’s Slope magnitude and variation rate were 21.6, 10.8, 6.00 and 4.4 mm/decade, respectively. The trend change-point analysis showed the initial rainfall change-point dates as 2002, 2005, 1988, and 2000 for Uyo, Benin, Port Harcourt, and Warri, respectively. These prove positive changing climatic conditions for rainfall in the study area. Erosion and flood control facilities analysis and design in the Niger Delta will require the application of Non-stationary IDF modelling.

关键词： Rainfall Time Series Data Climate Change Trend Analysis Variation Rate Change Point Dates Non-Parametric Statistical Test

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：