The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
D R Williams - One of the best experts on this subject based on the ideXlab platform.
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Analysis and Chemical Speciation of copper and zinc in wound fluid.
Journal of inorganic biochemistry, 2000Co-Authors: P W Jones, D M Taylor, D R WilliamsAbstract:A novel method for the analysis of trace element Chemical Speciation at parts per billion (ppb) levels in wound fluid samples both contributes to the fundamental inorganic biochemistry of the healing process and permits improved treatments. Potentiometric Stripping Analysis in combination with acid digestion has been used to quantify the total copper and zinc levels in a series of 0.5 ml samples of fluid obtained from surgical wounds. Further, the degree of blood contamination has been investigated using visible spectroscopy. The prevailing Chemical Speciation (Chemical forms) of these total concentrations of copper and zinc amongst low molecular mass ligands in wound fluid has been investigated by computer modelling using JESS, the Joint Expert Speciation System. The model, involving 38 components, generates in the region of 3500 individual low molecular mass complexes including copper, zinc, iron, calcium and manganese species, and predicts that the majority of low molecular mass (lmm) copper complexes are electrically net-neutral, whilst those of zinc are predominantly charged. Further studies indicate that supplementing the concentrations of histidine and tryptophan may increase the net-neutral zinc fraction, the optimum effect being achieved at pH=7.4. This may be important in transporting zinc into healing cells.
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Chemical Speciation applied to bio-inorganic chemistry.
Journal of inorganic biochemistry, 2000Co-Authors: D R WilliamsAbstract:The processes of converting new chemistry into new healthcare, environment-friendly, products are considerably facilitated when Chemical Speciation data are available. These identify causal links between Speciation and biological responses based upon specific Chemical species rather than total concentrations. The effective roles of bismuth for ulcer treatment, of Ca, Zn, Sn and F in dentifrices, and of zinc species and common cold symptoms are described. A new readily biodegradable ligand for minimising the environmental impact of washing powders, Al and Alzheimer's disease (and the absence of a causal link), and an audit of Cu and Zn flow from wound dressing through wound fluid to healing tissue, are all discussed in detail.
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PARSAFE: computer program for safety assessment and optimization of parenteral nutrition formulations based on Chemical Speciation analysis.
Nutrition (Burbank Los Angeles County Calif.), 1992Co-Authors: Simon B. Hall, D R Williams, J.r. Duffield, M. I. Barnett, A.g. CosslettAbstract:Instability arising from the formation of precipitates and lipid emulsion aggregates is common in parenteral nutrition formulations due to the concentration- and pH-dependent incompatibility of some of the vital ingredients. Previously, the boundaries between stability and instability could only be established through the use of laborious and expensive empirical methods. The predictive technique with the concept of Chemical Speciation (based on the analysis of many competitive thermodynamic equilibriums) has been adapted for use with parenteral fluids so that these detrimental events may now be avoided. A comprehensive computer program, PARSAFE ((C) 1991. Sponsors interested in this program should contact D.R.W.) has been developed for this purpose. PARSAFE encompasses Chemical-Speciation techniques and contains a large data base of commonly used intravenous fluid constituents together with the appropriate thermodynamic equilibrium constants describing their interactions so that stability prediction may be readily achieved in hospital pharmacy laboratories. We review the relevant physical chemistry required for the successful implementation of PARSAFE and outline the audit trails involved in the development of the predictive model.
David R. Williams - One of the best experts on this subject based on the ideXlab platform.
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Chemical Speciation contributing to research knowledge and everyday life
Coordination Chemistry Reviews, 1999Co-Authors: David R. WilliamsAbstract:Abstract The definition and determination of Chemical Speciation is described and how this parameter controls the behaviour of an element and its compounds. Examples are quoted in terms of the efficiency and biodegradability of ligands, trace metal complex migration in the environment, ‘more for less’ approaches to ligand usage, zinc and the common cold, the perception of toxicity of materials and healthcare such as dentistry. Definitions of ‘safe’ chemistry are discussed.
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Chemical Speciation of ethylenediamine-N,N′- disuccinic acid (EDDS) and its metal complexes in solution
Chemical Speciation & Bioavailability, 1999Co-Authors: Joanne S. Whitburn, Stephen D. Wilkinson, David R. WilliamsAbstract:Computer simulation of Chemical Speciation has been used to assess the ability of the readily-biodegradable ligand SS-EDDS4− to replace the non readily-biodegradable ligand EDTA4−. Potential replac...
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Chemical Speciation modelling and thermodynamic database compilation—I. Data uncertainties
Polyhedron, 1991Co-Authors: J.r. Duffield, F. Marsicano, David R. WilliamsAbstract:Abstract This article addresses the critical appraisal of thermodynamic data for inclusion in databases for use with computer-based Chemical Speciation models. The uses of Chemical Speciation analysis, the need for accurate and applicable thermodynamic data and the uncertainties associated with the modelling of “real-life” processes are considered. Where appropriate, examples are given to illustrate and expand upon individual points.
Abdul Rahim Ismail - One of the best experts on this subject based on the ideXlab platform.
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Chemical Speciation and contamination assessment of Zn and Cd by sequential extraction in surface sediment of Klang River, Malaysia
Microchemical Journal, 2010Co-Authors: Abolfazl Naji, Ahmad Ismail, Abdul Rahim IsmailAbstract:The concentration and Chemical Speciation of Cd and Zn as well as total organic carbon (TOC) were studied in surface sediments from 21 stations along Klang River. Sequential extraction technique (SET) was applied to assess the four (exchangeable, acid-reducible, oxidisable-organic and residual) fractions in surface sediment. And also, to obtain an overall classification of cadmium and zinc pollution in this area. This investigation was the first study on the basis of the Chemical Speciation of Cd and Zn in surface sediments of the Klang River. The total concentrations of metals were ranged (0.60–2.26 µg g− 1) for Cd and (33.26–268.24 µg g− 1) for Zn. The Chemical Speciation of Cd and Zn in most sampling stations were in the order of residual > acid-reducible > oxidisable-organic > exchangeable, and it showed that the Zn in Klang River surface sediments existed in the nonresistant fractions, whilst Cd existed in the resistant fraction. The degree of surface sediments contamination was determined for individual contamination factors (ICF) and global contamination factor (GCF). The result of ICF and GCF values showed that those stations located vicinity of municipal area had high potential risk to fauna and flora of the Klang River. The relationship between the concentration of cadmium and zinc at the oxidation-organic fraction with TOC in surface sediment was identified. The results showed that TOC had a positive function to complex with Cd and Zn in the surface sediment of Klang River.
Bo H. Svensson - One of the best experts on this subject based on the ideXlab platform.
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Chemical Speciation of Sulfur and Metals in Biogas Reactors : Implications for Cobalt and Nickel Bio-uptake Processes - Chemical Speciation of Sulfur and Metals in Biogas Reactors : Implications for Cobalt and Nickel Bio-uptake Processes
Journal of hazardous materials, 2016Co-Authors: Sepehr Shakeri Yekta, Ulf Skyllberg, Åsa Danielsson, Annika Björn, Bo H. SvenssonAbstract:This article deals with the interrelationship between overall Chemical Speciation of S, Fe, Co, and Ni in relation to metals bio-uptake processes in continuous stirred tank biogas reactors (CSTBR). To address this topic, laboratory CSTBRs digesting sulfur(S)-rich stillage, as well as full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were targeted. Sulfur Speciation was evaluated using acid volatile sulfide extraction and X-ray absorption spectroscopy. Metal Speciation was evaluated by Chemical fractionation, kinetic and thermodynamic analyses. Relative Fe to S content is identified as a critical factor for Chemical Speciation and bio-uptake of metals. In reactors treating sewage sludge, quantity of Fe exceeds that of S, inducing Fe-dominated conditions, while sulfide dominates in laboratory and co-digestion reactors due to an excess of S over Fe. Under sulfide-dominated conditions, metals availability for microorganisms is restricted due to formation of metal-sulfide precipitates. However, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by microorganisms under sulfidic conditions. Concentrations of free metal ions and labile metal complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This in turn enhances metal adsorption on cell surfaces and bio-uptake rates.
David M. Taylort - One of the best experts on this subject based on the ideXlab platform.
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NSPEC: a Chemical Speciation program for personal computers.
The Analyst, 1992Co-Authors: Gregory W. Quinn, David M. TaylortAbstract:The details of a computer program, NSPEC, which simulates Chemical Speciation in aqueous systems, are presented. NSPEC has been designed explicitly for the IBM PC family of computers and is a departure from normal Speciation programs in that it is controlled through interaction with a series of menus. The program is more user-friendly than other comparable Speciation programs, can write the results files in formats suitable for importing into other programs, and, in many instances gives results faster than Speciation programs running on microcomputers.
