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Abiotic predictors of fine sediment accumulation in lowland rivers

International Journal of Sediment Research 2022年第1期37卷 128-137页

作者： Morwenn McKenzie Judy England Ian D.L.Foster Martin A.Wilkes Geography and Environment Loughborough University Centre for Agroecology Water & Resilience Coventry University Research Environment Agency Howbery Park Environmental and Geographical Sciences University of Northampton Learning Hub University Drive Geography Department Rhodes University

The delivery of excessive fine sediment (particles<2 mm in diameter) to rivers can cause serious deleterious effects to aquatic ecosystems and is widely acknowledged to be one of the leading contributors to the degradation of rivers *** advances in using biological methods as a proxy,physical measures remain an important method through which fine sediment can be *** aim of this study was to provide further insights into the environmental variables controlling sediment accumulation in lowland gravel bed *** sampled 21 sites,during spring and autumn,selected to cover a gradient of excess fine *** sediment was sampled using a range of methods including visual assessments,the disturbance method,and suspended sediment concentrations.A range of abiotic predictors was measured during sampling,and hydrological and antecedent flow indices were derived from local flow gauging station *** results show reach scale visual estimates of fine sediment to be significantly and highly correlated with fully quantitative estimates of total surface *** regression analysis showed that flow variables (regime,antecedent,and local flow characteristics)were strong predictors of deposited sediment metrics but poor predictors of suspended *** content was shown to be relatively independent of total sediment quantity and is likely driven by other factors which influence the supply and breakdown of organic matter.

关键词： Deposited sediment Suspended sediment Visual assessments Disturbance Sediment sampling

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ZnTBPPc光物理化学性质的溶剂化效应(英文)

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物理化学学报 2011年第5期27卷 1045-1052页

作者： OGUNSIPE Abimbola NYOKONG Tebello Department of Chemistry Kwara State University P.M.B 1530 Ilorin Nigeria Department of Chemistry Rhodes University

The solvent viscosity dependence of the photophysical and photochemical properties of tetra(tert-butylphenoxy)phthalocyaninato zinc(II) (ZnTBPPc) is presented. The fluorescence quantum yields (ΦF) and Stern-Volmer′s constant (KSV) for ZnTBPPc fluorescence quenching by benzoquinone in all the solutions followed a semi-empirical law that depends only on the solvent viscosity. ΦF values vary between 0.08 in tetrahydrofuran (THF) and 0.14 in dimethylsulphoxide (DMSO). Triplet quantum yields (ΦT) and lifetimes (τT) also exhibit clear solvent viscosity dependence with the values being higher in the most viscous solvents. The interaction of the ZnTBPPc triplet state with oxygen was found to be diffusion- controlled, but higher rate constants were observed in low-viscosity solvents like THF and toluene. Absolute values of singlet oxygen quantum yields (ΦΔ) were determined, and the values are comparable in all the solvents, which is attributed to the proximity of the ZnTBPPc triplet energies in different solvents.

关键词：物理学知识 KSV ZnTBPPc

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Helicobacter pylori and colorectal neoplasia:Is there acausal link?

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World Journal of Gastroenterology 2016年第2期22卷 649-658页

作者： Vasilios Papastergiou Stylianos Karatapanis Sotirios D Georgopoulos Department of Internal Medicine General Hospital of Rhodes85100 RhodesGreece Department of Gastroenterology Athens MedicalPaleo Faliron General Hospital17562 AthensGreece

Ever since Helicobacter pylori(H. pylori) was recognized as an infectious cause of gastric cancer, there has been increasing interest in examining its potential role in colorectal carcinogenesis. Data from casecontrol and cross-sectional studies, mostly relying on hospital-based samples, and several meta-analyses have shown a positive statistical relationship between H. pylori infection and colorectal neoplasia. However, the possibility exists that the results have been influenced by bias, including the improper selection of patients and disparities with respect to potential confounders. While the evidence falls short of a definitive causal link, it appears that infection with H. pylori /H. pylori-related gastritis is associated with an increased, although modest, risk of colorectal adenoma and cancer. The pathogenic mechanisms responsible for this association remain uncertain. H. pylori has been detected in colorectal malignant tissues; however, the possibility that H. pylori is a direct activator of colonic carcinogenesis remains purely hypothetical. On the other hand, experimental data have indicated a series of potential oncogenic interactions between these bacteria and colorectal mucosa, including induction and perpetuation of inflammatory responses, alteration of gut microflora and release of toxins and/or hormonal mediators, such as gastrin, which may contribute to tumor formation.

关键词： Helicobacter pylori Colorectal cancer Polyp Adenoma Gastrin

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Current status and emerging challenges in the treatment of hepatitis C virus genotypes 4 to 6

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World Journal of Clinical Cases 2015年第3期3卷 210-220页

作者： Vasilios Papastergiou Stylianos Karatapanis Department of Internal Medicine General Hospital of Rhodes

Hepatitis C virus(HCV) genotypes 4, 5 and 6 are mainly present in Africa, the Middle East and Asia and they have been less extensively studied with respect to epidemiology, natural disease history and therapeutic endpoints. Response rates to a 48-wk combined peginterferon/ribavirin treatment range to 40%-69% for HCV 4, 55%-60% for HCV 5 and 60%-90% for HCV 6. Response-guided schedules are recommended to optimize the outcomes of peginterferon/ribavirin treatment in HCV 4 and, in form of preliminarydata, for HCV 6, but no data are yet available to support such an individualization of therapy for HCV 5. Recently, the direct-acting antivirals(DAAs) with pan-genotypic activities simeprevir, sofosbuvir and daclatasvir have been recommended in triple regimens with peginterferon/ribavirin for the treatment of HCV genotypes 4 to 6 infections. In the future, DAA-based interferon-free therapies are awaited to drastically improve treatment outcomes in HCV. However, efforts to improve treatment outcomes with peginterferon/ribavirin should continue, as the HCV 4-6 infected population is mainly based in resource-limited settings with restricted access to the costly DAAs.

关键词： Hepatitis C virus Genotype 4 Genotype 5 Genotype 6 Pegylated interferon Ribavirin Directacting antivirals

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Poly[β-(1→4)-2-amino-2-deoxy-D-glucopyranose] based zero valent nickel nanocomposite for efficient reduction of nitrate in water

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Journal of Environmental Sciences 2012年第9期24卷 1702-1708页

作者： Sheriff Adewuyi Nurudeen O.Sanyaolu Saliu A.Amolegbe Abdulahi O.Sobola Olujinmi M.Folarin Department of Chemistry College of Natural ScienceUniversity of Agriculture AbeokutaPMB 2240 AbeokutaOgun100001Nigeria Department of Chemistry Rhodes UniversityGrahamstown 6140South Africa Department of Polymer Technology Faculty of Engineering and the Built EnvironmentTshwane University of TechnologyPretoria 0001South Africa

Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion. One major drawback of this technique is the agglomeration of nanoparticles leading to the formation of large floes. A low cost biopolymeric material, poly [β-（1-4）-2-amino-2-deoxy-D-glucopyranose] （β-PADG） obtained from deacetylated chitin was used as stabilizer to synthesize zero valent nickel （ZVNi） nanoparticles. The β-PADG-ZVNi nanocomposite was characterized using infra red （IR）, UV-Vis spectrophotometric techniques and Scanning Electron Microscope （SEM）. The morphology of the composite showed that β-PADG stabilized-ZVNi nanoparticles were present as discrete particles. The mean particle size was estimated to be （7.76 ± 2.98） nm and surface area of 87.10 m2/g. The stabilized-ZVNi nanoparticles exhibited markedly greater reactivity for reduction of nitrate in water with 100% conversion within 2 hr contact owing to less agglomeration. Varying the β-PADG-to-ZVNi ratio and the ZVNi-to-nitrate molar ratio generally led to a faster nitrate reduction. About 3.4-fold difference in the specific reaction rate constant suggests that the application of the β-PADG-stabilizer not only increased the specific surface area of the resultant nanoparticles, but also greatly enhanced the surface reactivity of the nanoparticles per unit area.

关键词： poly [β-(1-→4)-2-amino-2-deoxy-D-glucopyranose] zerovalent nickel nitrate ion reduction

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Synthesis, characterization and biological applications of novel Schiff bases of 2-(trifluoromethoxy) aniline

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Journal of Chinese Pharmaceutical Sciences 2018年第5期27卷 307-323页

作者： Thierry Youmbi Fonkui Monisola Itohan Ikhile Freddy Munyololo Muganza Marthe Carine Djuidje Fotsing Charmaine Arderne Xavier Siwe-Noundou Rui Werner Macedo Krause Derek Tantoh Ndinteh Patrick Berka Njobeh Department of Biotechnology and Food Technology University of Johannesburg Department of Applied Chemistry University of Johannesburg Department of Chemistry Sefako Makgatho Health Sciences University Department of Chemistry University of Johannesburg Department of Chemistry Rhodes University

A series of five new Schiff bases(1–5) were synthesized by reacting 2-(trifluoromethoxy) aniline with different aromatic aldehydes. The Schiff base compounds were characterized by spectroscopic and analytical methods. Crystal structure of one new compound was also reported. The pharmacological properties, including antibacterial(14 bacterial species), antifungal(7 strains), antimalarial, anti-trypanosomal and anti-HIV activities of the compounds, were investigated. Cytotoxicity of the tested compounds was evaluated against human cervix adernocarcinoma cells(He La). Bacterial minimum inhibitory concentration(MIC) results by broth microdilution method showed that Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Proteus vulgaris, Klebsiella oxytoc and Klebsiella pneumonia were more sensitive in the presence of tested compounds with an MIC value of 15.6 μg/m L. All the tested compounds showed good to moderate activity against fungi. The sensitivity of Aspergillus fumigatus was higher than other strains with a minimum cell death concentration(MFC) of 15.6 μg/m L. Compound 1 showed greater antimalarial and anti-trypanosomal properties with very low to no cytotoxic effects against He La cells as compared with compound 5, while other compounds exhibited poor activity. Compounds 1–5 demonstrated good activity against HIV type-1. These Schiff base compounds could be used as good antimicrobial agents.

关键词： Synthesis Biological activity Schiff bases Antimicrobial 2-(Trifluoromethoxy) aniline

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Potentials and limitations of a system theory of macro-ergonomics

Potentials and limitations of a system theory of macro-ergon...

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第十七届国际工效学大会暨中国人类工效学会成立20周年庆祝大会

作者： Matthias Goebel Swantje Zschernack Department of Human Kinetics and Ergonomics Rhodes University

Macro-ergonomic interventions have shown many benefits in industrial ***,macro-ergonomics is still very much an expert task,joining ergonomics knowledge with the application experience in the practical *** a result,a broad expertise is needed for the application of macro-ergonomics and the prognosis of outcome comes along with some uncertainty due to the complexity of the *** general nature of work environments as a complex system creates the ambivalence that on the one side a predetermination is needed to provide objective planning options,but,on the other side,complexity in itself deals with fuzziness and *** that this conflict can’t be resolved,but the practical challenge to converge the two poles still applies,ergonomics must aim for separating both:providing a maximum consistent deterministic model and,at the same time,clearly identifying the aspects of complexity that are excluded from a deterministic consideration due to their *** proposed paper demonstrates the generation of a comprehensive work system model that incorporates many existing macro-ergonomic concepts from different disciplinary backgrounds into a comprehensive model,and that integrates work system modelling with operational and with work system *** allows joint consideration of design options with different regulatory levels on the operational,strategic and system design *** is reflected in this approach by limitations of the formal expression in terms of qualitative and quantitative ***,this approach allows provision of a framework for practical application-handling complex feedback systems-and respecting the inherent predictability limitations of such ***,again,helps to optimise the introduction of ergonomic principles to a maximum possible degree and clearly accept the limitations for anticipation and interference in real world systems.

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胶束催化体系中的对映选择性环醚化反应(英文)

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催化学报 2011年第2期32卷 231-234页

作者： Bhupesh S. SAMANT Sunil S. BHAGWAT Natural Product and Medicinal Chemistry Research Group Division of Pharmaceutical chemistryFaculty of Pharmacy Rhodes University Grahamstown Department of Chemical Engineering Institute of Chemical Technology

The enantioselective cycloetherification of substituted keto phenols into their corresponding dihydrobenzofuran derivatives was carried out using hydrogen peroxide and chiral quaternary ammonium iodide in micellar media. This approach increased the conversion rate of cycloetherification and also widened the scope of this particular reaction for various substituted keto phenols with electron withdrawing as well as electron donating functionalities. The use of a surfactant in the cycloetherification reaction increased the yield of the corresponding enantioselective dihydrobenzofuran four times. The conversion rate of keto phenols into their corresponding dihydrobenzofuran derivatives was proportional to the concentration of the surfactant used in the reaction.

关键词： enantioselective cycloetherification dihydrobenzofuran derivative micellar catalysis

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Socio-economic factors influencing household forest dependency in Chobe enclave, Botswana

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Ecological Processes 2017年第1期6卷 417-426页

作者： Hesekia Garekae Olekae Tsompie Thakadu Joyce Lepetu Department of Environmental Science Rhodes UniversityP.O.Box 94GrahamstownSouth Africa Okavango Research Institute University of BotswanaPrivate Bag 285MaunBotswana Department of Crop Science and Production Botswana University of Agriculture and Natural ResourcesPrivate Bag 0027GaboroneBotswana

Introduction:Human dependence on forests is a multifaceted *** degree of reliance on forests varies geographically,overtime and across *** dynamics underpin the importance of understanding the determinants of household reliance on forests for the long-term sustainable forest management and *** paper presents an analysis of socio-economic determinants on the level of household forest dependency in Chobe enclave,*** study hypothesised that the level of household forest dependency will significantly differ across a range of socio-economic ***:Data was collected through a structured questionnaire survey of 183 households,randomly selected from three communities bordering Chobe Forest *** logistic regression model was used for analysing ***:Results showed that age and education significantly influenced household reliance on forests,while other socio-economic factors were not *** dependency was observed to be decreasing with an increase on both respondent age and educational ***,the youth were likely to be more reliant on forest products compared to their elderly counterpart while higher educational attainment lessened reliance on forest ***:In order to foster a balance between forest dependency and biodiversity conservation,alternative opportunities and provision and access to higher education aimed at diversifying young people’s livelihood activities are vital in reducing forest dependency,hence protecting forests for posterity.

关键词： Forest dependency Biodiversity conservation Rural-urban migration Chobe Forest Reserve Botswana

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Bioremediation of Distilled Winery Effluent Using Aerobic Digestion

Bioremediation of Distilled Winery Effluent Using Aerobic Di...

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7th World Congress on Recovery, Recycling and Re-integration

作者： James Strong rhodes university 36 Wattle Road 6530 South Africa

The project entails the pretreatment of distilled winery effluent by aerobic digestion using fungi. The fungi decrease the COD, total phenol concentration, and raise the pH to a level whereby further treatment by anae... 详细信息

关键词： wine effluent, polyphenols, laccase

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