检索结果-南通市图书馆

Diffusive transport of two charge equivalent and structurally similar ruthenium complex ions through graphene oxide membranes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2015年第4期8卷 1128-1138页

作者： Michael Coleman Xiaowu (Shirley) Tang Department of Chemistry 200 University Ave West Waterloo Ontario N2L 3G1 Canada Waterloo Institute for Nanotechnology 200 University Ave West Waterloo Ontario N2L 3G 1 Canada

Here, we report a study of ion transport across graphene oxide （GO） membranes of various thicknesses, made by vacuum filtration of GO aqueous solutions. The diffusive transport rates of two charge-equivalent ruthenium complex ions Ru（bpy）3^2＋ and Ru（phen）32% with a sub-angstrom size difference, are distinguishable through GO membranes and their ratio can be a unique tool for probing the transport-relevant pore structures. Pore and slit-dominant hindered diffusion models are presented and correlated to experimental results. Our analysis suggests that ion transport is mostly facilitated by large pores （larger than 1.75 nm in diameter） in the relatively thin GO membranes, while slits formed by GO stacking （less than 1.42 nm in width） become dominant only in thick membranes. By grafting PEG molecules to the lateral plane of GO sheets, membranes with enlarged interlayer spacing were engineered, which showed drastically increased ion transport rates and lower distinction among the two ruthenium complex ions, consistent with the prediction by the slit-dominant steric hindered diffusion model.

关键词： graphene oxide ion transport hindered diffusion nanofluidics

Chemical Characterization of lake Togbadji

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Water Resource and Protection 2023年第12期15卷 721-753页

作者： Vitalique Elegbede Dominique Kpadonou Joël Dossou-Gbete Magloire Acakpo Nonvignon Gbaguidi Bienvenu Olatundji Ogoudele Doctoral School of Exact and Applied Sciences University of Abomey-Calavi (UAC) Abomey-Calavi Benin Ecotoxicology and Quality Study Research Unit Applied Chemistry Study and Research Laboratory Department of Chemical Engineering-Processes (GC-P) Polytechnic School of Abomey-Calavi University of Abomey-Calavi Abomey-Calavi Benin

The present study focused on the chemical characterization of the watercourse of the Togbadji lake wildlife ranch. The methodological approach followed is as follows: Bibliography review, Sampling campaign. The results obtained were the subject of descriptive statistics, the two-sample Wilcoxon test to determine the impact of different localities on the abundance of microbiological contaminants, a Principal Component Analysis (PCA) with the software R version 3.5.0, in order to group the pollution parameters according to the different levels and sources of contamination. From our results, it is found that the respective average values in dry and rainy seasons for ammonium ions are 0.38 ± 0.16 mg/l and 0.22 ± 0.03 mg/l;for nitrite ions 0.20 ± 0.25 mg/l and 0.02 ± 0.01 mg/l;for nitrate ions 3.72 ± 2.52 mg/l and 7.84 ± 4.91 mg/l;for total Kjeldahl nitrogen 1.27 ± 1.44 mg/l and 1.19 ± 1.49 mg/l;for orthophosphate ions 0.20 ± 0.25 mg/l and 0.02 ± 0.01 mg/l;for total phosphorus 0.04 ± 0.01 mg/l and 0.11 ± 0.23 mg/l;the chemical oxygen demand 93.36 ± 61.73 mg/l of O2 and 89.93 ± 66.11 mg/l of O2 and the biochemical oxygen demand over 5 days 25.50 ± 18.22 mg/l of O2 and 37 ± 33.15 of O2. It emerged that the main sources of pollution in lake Togbadji are runoff water, discharges of various wastewater from artisanal activities, livestock farming and open defecation.

关键词： Chemical Degradation Aquatic Environment lake Togbadji

Surface modification of nanozymes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2017年第4期10卷 1125-1148页

作者： Biwu liu Juewen liu Department of Chemistry Waterloo Institute for Nanotechnology University of Waterloo Waterloo Ontario N2L 3G 1 Canada

Nanoparticles and proteins are similar in a number of aspects, and using nanoparticles to mimic the catalytic function of enzymes is an interesting yet challenging task. Impressive developments have been made over the past two decades on this front. The term nanozyme was coined to refer to nanoparticle- based enzyme mimics. To date, many different types of nanozymes have been reported to catalyze a broad range of reactions for chemical, analytical, and biomedical applications. Since chemical reactions happen mainly on the surface of nanozymes, an interesting aspect for investigation is surface modification. In this review, we summarize three types of nanozyme materials catalyzing various reactions with a focus on their surface chemistry. For metal oxides, cerium oxide and iron oxide are discussed as they are the most extensively studied. Then, gold nanoparticles and graphene oxide are reviewed to represent metallic and carbon nanomaterials, respectively. Types of modifications include ions, small molecules, and polymers mainly by physisorption, while in a few cases, covalent modifications were also employed. The functional aspect of such modification is to improve catalytic activity, substrate specificity, and stability. Future perspectives of this field are speculated at the end of this review.

关键词： enzyme-mimics nanozymes adsorption peroxidases biosensors

Gold nanoparticles as dehydrogenase mimicking nanozymes for estradiol degradation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical letters 2019年第9期30卷 1655-1658页

作者： Zijie Zhang leslie M. Bragg Mark R. Servos Juewen liu Department of Chemistry Waterloo Institute for Nanotechnology University of Waterloo Waterloo Ontario N2L 3G1 Canada Department of Biology University of Waterloo Waterloo Ontario N2L 3G1 Canada

Nanozyme catalysis has been mainly focused on a few chromogenic and fluorogenic substrates, while environmentally and biologically important compounds need to be tested to advance the field. In this work, we studied oxidation of estradiol(E2) in the presence of various nanomaterials including gold nanoparticles(AuNPs), nanoceria(CeO2), Fe3O4, Fe2O3, MnO2 and Mn2O3, and found that AuNPs had a dehydrogenase-mimicking activity to convert E2 to estrone(E1). This conversion was monitored using HPlC. The reaction was faster at higher pH and reached saturation at pH 8. Smaller AuNPs had a higher catalytic efficiency and 5 nm AuNPs were 4.8-fold faster than 13 nm at the same total surface area. Finally,we tried 17α-ethinylestradiol(EE2) as a substrate and found that 5 nm AuNPs can catalyze EE2 oxidation in the presence of H2O2. This work indicated that some nanomaterials can affect environmentally important hormones via oxidation reactions, and this study has expanded the scope of substrate of nanozymes.

关键词： Nanozymes Estradiol Gold nanoparticles Catalysis Environment HPlC

Explicit H1-Estimate for the Solution of the lamé System with Mixed Boundary Conditions

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

Journal of Partial Differential Equations 2020年第1期33卷 64-92页

作者： AIT-AKlI Djamel MERAKEB Abdelkader l2CSP Mouloud Mammeri University Tizi-Ouzou15000Algeria

In this paper we consider the lamé system on a polygonal convex domain with mixed boundary conditions of Dirichlet-Neumann *** explicit l2 norm estimate for the gradient of the solution of this problem is *** leads t... 详细信息

关键词： lamésystem Korn's inequality Poincare's inequality inequality of trace explicit estimates

Barriers to Insurance as a Flood Risk Management Tool:Evidence from a Survey of Property Owners

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Disaster Risk Science 2020年第3期11卷 263-273页

作者： Jason Thistlethwaite Daniel Henstra Craig Brown Daniel Scott School of Environment Enterprise and DevelopmentUniversity of WaterlooWaterlooON N2L 3G1Canada Department of Political Science University of WaterlooWaterlooON N2L 3G1Canada Climate Change and Health Adaptation Planning Vancouver Coastal HealthVancouverBC V5Z 4C2Canada Department of Geography and Environmental Management University of WaterlooWaterlooON N2L 3G1Canada

By using risk-adjusted price signals to transfer responsibility for property-level flood protection and recovery from governments to property owners,flood insurance represents a key tenet of the flood risk management(FRM)*** Government of Canada has worked with insurers to introduce flood insurance for the first time as a part of a broader shift towards FRM to limit the growing costs of *** viability of flood insurance in Canada,however,has been questioned by research that disputes the utility of purchasing coverage by property *** study tested this assumption by drawing on public opinion survey data to assess factors that influence decisions about the utility of *** findings reveal that Canadians have limited knowledge of flood insurance coverage,exhibit a low willingness-to-pay for both insurance and property-level flood protection measures,and expect governments to shoulder much of the financial burden of flood recovery through disaster assistance.

关键词： Flood insurance Flood risk management Risk-sharing Willingness-to-pay

Potential of Biostimulants Based on PGPR Rhizobacteria Native to Benin’s Soils on the Growth and Yield of Maize (<i>Zea mays </i>l.) under Greenhouse Conditions

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

Open Journal of Soil Science 2021年第3期11卷 177-196页

作者： Marcel Y. Adoko Haziz Sina Olaréwadjou Amogou Nadège A. Agbodjato Pacôme A. Noumavo Ricardos M. Aguégué Sylvestre A. Assogba Nestor Ahoyo Adjovi Gustave Dagbénonbakin Adolphe Adjanohoun lamine Baba-Moussa laboratory of Biology and Molecular Typing in Microbiology Department of Biochemistry and Cellular Biology University of Abomey Calavi (UAC) Cotonou Benin laboratory of Microbiology and Food Technology Department of Plant Biology University of Abomey Calavi (UAC) Cotonou Benin National Agricultural Research Institute of Benin (INRAB) Benin

The application of biostimulants in agriculture represents an environmentally friendly alternative while increasing agricultural production. The aims of the study were to develop solid biostimulants based on five rhizobacteria native to Benin’s soils and to evaluate their efficacy on the growth and biomass yield of maize under greenhouse conditions on ferrallitic and ferruginous soils. Clay and peat were used as a conservation binder for the preparation of the biostimulants. These binders were used alone or combined in the different formulations with maize flour and sucrose. 10 g of biostimulants were applied at sowing in pots containing five kilograms of sterilised soil. The experimental design was a completely randomised block of 24 treatments with three replicates. The results obtained showed significant improvements (P 2.7%), leaf area (66.10%), above-ground biomass (97.12%) and below-ground biomass (53.98%) on ferrallitic soil with the application of the clay + Pseudomonas putida biostimulant compared to the control. On the other hand, the use of the peat biostimulant + Pseudomonas syringae was more beneficial for plant growth on ferruginous soil. The height, stem diameter, leaf area, above-ground biomass and below-ground biomass of the plants under the influence of this biostimulant were improved by 83.06%, 44.57%, 102.94%, 86.84% and 42.68%, respectively, compared to the control. Therefore, these results confirm that Rhizobacteria express their potential through biostimulants formulated on maize. The formulated biostimulants can later be used by producers to improve crop productivity for sustainable agriculture.

关键词： Biostimulants Plant Growth Promoting Rhizobacteria Soil Fertility Binder Corn Benin

A SIMPlE PROOF OF THE INEQUAlITY FFD (l)≤11/9 OPT(l)+1, ■l FOR THE FFD BIN-PACKING AlGORITHM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 1991年第4期7卷 321-331页

作者：越民义 Institute of Applied Mathematics Academia Sinica Beijing Forschungsinstitut fur Diskrete Mathematik Bonnhe first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L letOPT(L) denote the minimal number of bins into which L can be packed and let FFD(L)denote the number of bins used by FFD. Johnson showed that for every list L FFD(L)≤11/9OPT(L)+4. His proof required more than 100 pages. Later Baker gave a much shorterand simpler proof for FFD(L)≤11/9OPT(L)+3. His proof required 22 pages. In this paperwe give a proof for FFD(L)≤11/9 OPT(L)+1. The proof is much simpler than the previousones.

The first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list l, letOPT(l) denote the minimal number of bins into which l can be packed, and let FFD(l)denote the number of bins used by FFD. Johnson showed that for every list l, FFD(l)≤11/9OPT(l)+4. His proof required more than 100 pages. later, Baker gave a much shorterand simpler proof for FFD(l)≤11/9OPT(l)+3. His proof required 22 pages. In this paper,we give a proof for FFD(l)≤11/9 OPT(l)+1. The proof is much simpler than the previousones.

关键词： A SIMPlE PROOF OF THE INEQUAlITY FFD l FOR THE FFD BIN-PACKING AlGORITHM BIN OPT

Effect of temperature in the conversion of methanol to olefins （MTO） using an extruded SAPO-34 catalyst

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

Frontiers of Chemical Science and Engineering 2018年第2期12卷 226-238页

作者： Ignacio Jorge Castellanos-Beltran Gnouyaro Palla Assima Jean-Michel lavoie Universit6 de Sherbrooke Chaire de Recherche Industrielle sur l'Ethanol Cellulosique et les Biocommodities (CRIEC-B) Sherbrooke QC Canada J1L 2Y4

The methanol-to-olefin （MTO） reaction was investigated in a bench-scale, fixed-bed reactor using an extruded catalyst composed of a commercial SAPO-34 （65 weight percentage, wt-%） embedded in an amorphous SiO2 matrix （35 wt-%）. The texture properties, acidity and crystal structure of the pure SAPO-34 and its extruded form （E-SAPO-34） were analyzed and the results indicated that the extrusion step did not affect the properties of the catalyst. Subsequently, E-SAPO-34 was tested in a temperature range between 300 and 500 ~C, using an aqueous methanol mixture （80 wt-% water content） fed at a weight hour space velocity （WHSV） of 1.21 h-1. At 300 ~C, a low conversion was observed combined with the catalyst deactivation, which was ascribed to oligomeriza-tion and condensation reactions. The coke analysis showed the presence of diamandoid hydrocarbons, which are known to be inactive molecules in the MTO process. At higher temperatures, a quasi-steady state was reached during a 6 h reaction where the optimal temperature was identified at 450℃, which incidentally led to the lowest coke deposition combined with the highest H/C ratio. Above 450℃, surges of ethylene and methane were associated to a combination of H-transfer and protolytic cracking reactions. Finally, the present work underscored the convenience of the extrusion technique for testing catalysts at simulated scale-up conditions.

关键词： MTO SAPO-34 temperature extrusion coke light alkanes