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Preliminary studies on the stability of arsenolipids:Implications for sample handling and analysis

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Journal of Environmental Sciences 2016年第11期28卷 97-103页

作者： Muslim Khan kevin A.Francesconi Institute of Chemistry-Analytical Chemistry University of Graz

Human health risk assessments concerning arsenic are now estimating exposure through food in addition to exposure through drinking water. Intrinsic to this assessment is sample handling and preparation that maintains the arsenic species in the form that they occur in foods. We investigated the stability of three arsenolipids（two arsenic fatty acids, As FA-362 and As FA-388, and one arsenic hydrocarbon As HC-332）, common constituents of fish and algae, relevant to sample storage and transport, and to their preparation for quantitative measurements. The fate of the arsenolipids was followed by high performance liquid chromatography/electrospray triple quadruple mass spectrometry（HPLC/ESIMS） *** of the compounds dry as pure compounds or mixed in fish oil at up to 60？C did not result in significant changes to the compounds, although losses were observed by apparent adsorption onto the plastic walls of the polypropylene tubes. No losses occurred when the experiment was repeated with glass tubes. When the compounds were stored in ethanol for up to 15 days under acidic, neutral, or alkaline conditions（each at room temperature）, no significant decomposition was observed, although esterification of the fatty acids occurred at low p H. The compounds were also stable during a sample preparation step involving passage through a small silica column. The results indicate that these typical arsenolipids are stable when stored in glass at temperatures up to 60？C for at least 2 days, and that,consequently, samples of food or extracts thereof can be transported dry at ambient temperatures, i.e. without the need for cool conditions.

关键词： Arsenolipids Stability Mass spectrometry

Case study and design of steel set support for aged belt entry rehabilitation

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International Journal of Mining Science and Technology 2018年第1期28卷 101-106页

作者： kevin Jinrong Ma John Stankus Keystone Mining Services LLC

In order to access remote reserve areas, some *** mines have to maintain aged underground entries for a great ***, high humidity, warm temperature, and time dependent deterioration can cause progressive roof deterioration and unexpected roof falls, and pose a great challenge to ground control *** an active belt structure in place and limited space, re-bolting becomes very costly, less effective,and, sometimes, impractical and *** gain long-term entry stability and serviceability, operators typically rehabilitate the aged belt entries by installing standing steel set *** the last several years,Keystone Mining Services, LLC,(KMS) has assisted many coal mines with their belt entry rehabilitation projects, evaluated the ground condition of various aged belt entries, and designed different standing steel set support *** paper presents a case study of a large-scale roof fall that occurred at an aged belt entry in a mine located in an eastern coalfield, analyzes root causes of excessive deformation of square sets that were installed in an adjacent entry, evaluates the adequacy of an existing rehabilitation square set, and develops remedial recommendations for future rehabilitation *** on the case study, the paper outlines design guidelines for rehabilitation steel sets that include field evaluation, engineering considerations, design assumptions, steel structural analysis, and field installation quality control.

关键词： Coal mine Roof fall Belt entry Rehabilitation Steel set support

Experimental study on modification of water-based filtercake to improve the bonding strength at the wellbore cement-formation interface

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Petroleum Research 2023年第4期8卷 531-540页

作者： kevin Nsolloh Lichinga Department of Engineering Development Tanzania Industrial Research and Development Organization(TIRDO)PO Box 23235Dar es SalaamTanzania Department of Petroleum Engineering Faculty of Earth Resources for Oil Well Cement Research and TestingNo.388Lumo RoadHongshan DistrictWuhanChina University of GeosciencesWuhan430074PR China

The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface(WCFI),so as to ensure long-term zonal isolation throughout the lifecycle of the well by using NsO solution as filtercake modifier which was developed in the *** to designed experimental method and API RP 10,the effectiveness of filtercake modifier(NSO)on the bonding strength at the WCFI was assessed by using designed simulated wellbore as sandstone *** experimental results indicated that the samples which were treated with NsO solution had higher bond strength over untreated *** strength generally increased with curing period as for treated samples,0.198,0.374,0.433 and 0.473 MPa for 3,7,15,and 30 days respectively while for the untreated samples the bond strength were 0.050,0.070,0.81 and 0.100 MPa for the same *** water-based filtercake modification techniques had significantly enhanced the bonding strength of WCFI by increasing rates above 296%.Improvement of bond strength to the treated sample was due to filtercake modification as a result of formation of cementitious material as revealed in FTIR spectral such as Calcium-Silicate-Hydrate(C-S-H)and other geopolymers like Calcium-Aluminium-Silicate-Hydrate(C-A-S-H)and Sodium-Aluminium-Silicate-Hydrate(N-A-S-H)along the interface which filled the existed pores hence reducing porosity hence high strength of *** low transmittance value for the NsO treated samples revealed that there were more cementitious materials existing at the WCFI which led to improvement of bonding strength as compared to the untreated *** lower/poor bond strength for the untreated samples is due to existence of untreated,thick water-based filtercake films at WCFI,which prevented the complete hydration process between rock grains and cement slurry components to make chemical binder of cement slurry material and formation.2022 The Authors.P

关键词： Geopolymer Bond strength Water-based mud Wellbore cement-formation interface NSO

Discrete element modelling of the quasi-static uniaxial compression of individual infant formula agglomerates

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Particuology 2012年第5期10卷 523-531页

作者： kevin J.Hanley Catherine O'Sullivan Edmond P.Byrne kevin Cronin Department of Process and Chemical Engineering University College CorkCorkIreland Department of Civil and Environmental Engineering Skempton BuildingImperial College LondonLondon SW7 2AZ United Kingdom

Infant formula is usually produced in an agglomerated powder form. These agglomerates are subjected to many transient forces following their manufacture. These can be difficult to quantify experimentally because of their small magnitudes and short durations, Numerical models have the potential to address this gap in the experimental data. The objective of the research described here was to calibrate a discrete element model for these agglomerates using experimental data obtained for quasi-static loading, and to use this model to study the mechanics of the particle response in detail. The Taguchi method was previously proposed as a viable calibration approach for discrete element models. In this work, the method was assessed for calibration of the model parameters （e.g., bond stiffnesses and strengths） considering three responses： the force at failure, strain at failure and agglomerate stiffness. The Weibull moduli for the simulation results and the experimental data were almost identical following calibration and the 37% characteristic stresses were similar. An analysis of the energy terms in the model provided useful insight into the model response. The bond energy and the normal force exerted on the platens were strongly correlated, and bond breakage events coincided with the highest energy dissipation rates.

关键词： Discrete element modellingUniaxial compressionQuasi-static crushingSimulationGranular materialsTaguchi methods

FEARCF a multidimensional free energy method for investigating conformational landscapes and chemical reaction mechanisms

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Science China Chemistry 2011年第12期54卷 1962-1973页

作者： NAIDOO kevin J. Scientific Computing Research Unit and Department of Chemistry University of Cape Town

The development and implementation of a computational method able to produce free energies in multiple dimensions,descriptively named the free energies from adaptive reaction coordinate forces(FEARCF) method is described in this *** the method can be used to calculate free energies of association,conformation and reactivity here it is shown in the context of chemical reaction landscapes.A reaction free energy surface for the Claisen rearrangement of chorismate to prephenate is used as an illustration of the method's efficient *** simulations are shown to achieve flat histograms for complex multidimensional free energy *** sampling efficiency by which it produces multidimensional free energies is demonstrated on the complex puckering of a pyranose ring,that is described by a three dimensional W(θ1,θ2,θ3) potential of mean force.

关键词： free energy calculations reaction dynamics reaction surfaces multidimensional free energy surfaces

Phenotypic trait matching predicts the topology of an insular plant–bird pollination network

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Integrative Zoology 2018年第3期13卷 339-347页

作者： Matthew BIDDICK kevin CBURNS School of Biological Sciences Victoria University of WellingtonWellingtonNew Zealand

Conceptualizing species interactions as networks has broadened our understanding of ecological ***,the factors shaping interaction patterns among species and,therefore,network structure remain *** potentially important factor is the matching of phenotypic ***,we tested for trait matching in a bird–flower visitation network from New *** first quantified the overall network structure and tested whether flower size could account for differences in the visitation rates of flowering *** then explored the relationship between the flower size and bill *** results showed that the interaction network is *** species with large flowers received more visits from birds than plant species with small ***,plant species with large flowers were visited more frequently by birds with large bills,while species with smaller flowers were visited more frequently by birds with small ***,the interaction patterns between birds and flowering plants could be predicted by their morphology,suggesting that phenotypic trait matching is an important predictor of network structure.

关键词： bird-flower visitation network flower morphology plant-animal interactions size coupling

Layer-layout-based heuristics for loading homogeneous items into a single container

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1944-1952页

作者： WANG Zhou-jing LI kevin W Department of Automation Xiamen University Xiamen 361005 China Odette School of Business University of Windsor Windsor Ontario N9B 3P4 Canada

The container loading problem (CLP) is a well-known NP-hard problem. Due to the computation complexity, heuristics is an often-sought approach. This article proposes two heuristics to pack homogeneous rectangular boxes into a single container. Both algorithms adopt the concept of building layers on one face of the container, but the first heuristic determines the layer face once for all, while the second treats the remaining container space as a reduced-sized container after one layer is loaded and, hence, selects the layer face dynamically. To handle the layout design problem at a layer's level, a block-based 2D packing procedure is also developed. Numerical studies demonstrate the efficiency of the heuristics.

关键词： Container loading problem (CLP) Heuristic Laver Packing. Optimization

A column study of the hydro-mechanical behavior of mature fine tailings under atmospheric drying

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International Journal of Mining Science and Technology 2017年第2期27卷 203-209页

作者： Anis Roshani Mamadou Fall kevin Kennedy Department of Civil Engineering University of OttawaOttawa KIN 6N5Canada

In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the *** a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.

关键词： Tailings Oil sand Environment Drying Multi-lift deposition

A NOVEL APPROACH TO CHARACTERIZING HESITATIONS IN INTUITIONISTIC FUZZY NUMBERS

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Journal of Systems Science and Systems Engineering 2013年第3期22卷 283-294页

作者： Minji HUANG kevin W.LI Department of Automation Xiamen University Odette School of Business University of Windsor

Building upon the concept of Dα operator introduced by Atanassov （1989）, thin article proposes an improved objective approach and a hybrid approach to operationalize Dα so that the hesitation in an intuitionistic fuzzy number （IFN） can be further refined and characterized. Numerical experiments are carried out to demonstrate the features and novelty of the proposed approach compared to existing methods in the literature. The aim is to furnish an effective way to refine hesitations in intuitionistic fuzzy assessments for more reliable and confident decision aids.

关键词： Intuitionistic fuzzy numbers fuzzy numbers hesitation Dα operator