The Experts below are selected from a list of 31668 Experts worldwide ranked by ideXlab platform
Graham A. Mills - One of the best experts on this subject based on the ideXlab platform.
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Urine 4-heptanone: a β-oxidation product of 2-ethylhexanoic acid from Plasticisers
Clinica Chimica Acta, 2001Co-Authors: Valerie Walker, Graham A. MillsAbstract:4-Heptanone is a common volatile constituent of human urine and is of unknown origin. We hypothesised that it arises from in vivo β-oxidation of 2-ethylhexanoic acid (EHA) from Plasticisers, similar to formation of 3-heptanone from valproic acid. We investigated urine from individuals with normal and increased Plasticiser exposure. Using GC/MS, solvent-extracted organic acids were analysed as trimethylsilyl (TMS) derivatives and heptanone with headspace solid-phase microextraction. We identified 3-oxo-2-ethylhexanoic acid, the β-oxidation product of EHA, as an enol in all samples. This is the first report of its TMS mass spectrum. We also found 2-ethyl-1,6-hexanedioic acid and 5-hydroxyEHA, ω- and ω-1-oxidation products of EHA, respectively, and 2-ethylhexanoylglucuronide, but only in trace amounts in some Plasticiser samples. These compounds have not been reported in human urine, nor has the TMS mass spectrum of 5-hydroxyEHA. The median concentrations of 3-oxoethylhexanoic acid and total 4-heptanone of seven Plasticiser samples were around 30–175-fold higher than normal samples. 4-Heptanone was barely detectable and 3-oxoethylhexanoic acid was not increased in an eighth Plasticiser sample, from a baby with deficiency of 2-methylbranched-chain acyl-CoA dehydrogenase. β-Oxidation is a major catabolic pathway of EHA in man, and might be involved in the metabolism of other branched-chain drugs and environmental pollutants.
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Urine 4-heptanone: a beta-oxidation product of 2-ethylhexanoic acid from Plasticisers.
Clinica Chimica Acta, 2001Co-Authors: Valerie Walker, Graham A. MillsAbstract:4-Heptanone is a common volatile constituent of human urine and is of unknown origin. We hypothesised that it arises from in vivo beta-oxidation of 2-ethylhexanoic acid (EHA) from Plasticisers, similar to formation of 3-heptanone from valproic acid. We investigated urine from individuals with normal and increased Plasticiser exposure. Using GC/MS, solvent-extracted organic acids were analysed as trimethylsilyl (TMS) derivatives and heptanone with headspace solid-phase microextraction. We identified 3-oxo-2-ethylhexanoic acid, the beta-oxidation product of EHA, as an enol in all samples. This is the first report of its TMS mass spectrum. We also found 2-ethyl-1,6-hexanedioic acid and 5-hydroxyEHA, omega- and omega-1-oxidation products of EHA, respectively, and 2-ethylhexanoylglucuronide, but only in trace amounts in some Plasticiser samples. These compounds have not been reported in human urine, nor has the TMS mass spectrum of 5-hydroxyEHA. The median concentrations of 3-oxoethylhexanoic acid and total 4-heptanone of seven Plasticiser samples were around 30--175-fold higher than normal samples. 4-Heptanone was barely detectable and 3-oxoethylhexanoic acid was not increased in an eighth Plasticiser sample, from a baby with deficiency of 2-methylbranched-chain acyl-CoA dehydrogenase. beta-Oxidation is a major catabolic pathway of EHA in man, and might be involved in the metabolism of other branched-chain drugs and environmental pollutants.
Eric Leroy - One of the best experts on this subject based on the ideXlab platform.
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On the representative elementary size concept to evaluate the compatibilisation of a plasticised biopolymer blend
Carbohydrate Polymers, 2017Co-Authors: Justin Favero, Sofiane Belhabib, Sofiane Guessasma, Paul Decaen, Anne-laure Reguerre, Denis Lourdin, Eric LeroyAbstract:This study combines experimental and numerical approaches to investigate the microstructure and mechanical behaviour of non-miscible plasticised starchi/zein blends. The concept of Representative Elementary Size (RES) is used to rank the effect of five different Plasticisers (cholinium acetate, glycerol, butyl methyl imidazolium chloride, glycerol-choline chloride, urea-choline chloride) inducing microstructural and mechanical changes in the blends. Microstructural and mechanical RESs are derived from microscopy image analysis and Finite Element Modelling of elasticity behaviour of studied blends. Compared to the usual consideration of ultimate mechanical properties (elongation and stress at break), the RES-based approach allows detecting the presence of perfect or imperfect interface between starch and zein particles depending on the nature of Plasticiser.
Younes Zahedi - One of the best experts on this subject based on the ideXlab platform.
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characterisation of a new biodegradable edible film based on sage seed gum influence of Plasticiser type and concentration
Food Hydrocolloids, 2015Co-Authors: Seyed Mohammad Ali Razavi, Asad Mohammad Amini, Younes ZahediAbstract:The present work dealt with investigating physicochemical, barrier, mechanical and surface properties of sage seed gum (SSG) edible films as a function of Plasticiser type (glycerol and sorbitol) and concentration (20, 40, 60, 80 & 100, w/w%). Based on the results, it was revealed that glycerol and sorbitol effectively plasticise the films of SSG while glycerol efficiency was higher than sorbitol. Although the films plasticised by glycerol were of high moisture content (27–49%), moisture uptake (110–140%) and solubility in water (∼80%), but they exhibited low permeability to water vapour, acceptable mechanical properties, surface hydrophilicity, and transparency. In contrast, the films plasticised by different concentrations of sorbitol exhibited a low moisture content (∼14%), water vapour permeability (lower than 4 × 10−11 g/m.s.Pa), and moisture uptake (below 90%) with high surface hydrophobicity but less desirable mechanical properties. The probable mechanisms of plasticising are discussed in details regarding the observed characteristics of SSG edible films. Concluding, the films of SSG in present work showed a substantial potential to be incorporated in food packaging applications.
Manuel Ferrandezvillena - One of the best experts on this subject based on the ideXlab platform.
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study of waste jute fibre panels corchorus capsularis l agglomerated with portland cement and starch
Polymers, 2020Co-Authors: Maria Teresa Ferrandezgarcia, Clara Eugenia Ferrandezgarcia, Teresa Garciaortuno, Antonio Ferrandezgarcia, Manuel FerrandezvillenaAbstract:This paper presents an experimental study on the bond behaviour of cement panels reinforced with plant fibres from the recycling of waste jute bags, using starch as a Plasticiser. During processing, different proportions of jute (5 wt %, 10 wt %, 15 wt %, and 20 wt %) were used with respect to the weight of cement, and the mixture was exposed to a pressure of 2.6 MPa and a temperature of 100 °C. The density, swelling thickness, internal bonding, flexural strength, and thermal conductivity were studied. Mechanical tests indicated that the values of the modulus of rupture (MOR) and the modulus of elasticity (MOE) increased over time; thus, the jute particles appeared to be protected by the plasticised starch and no degradation was observed. At 28 days, the particleboard with 5% starch had an MOR of 12.82 MPa and an MOE of 3.43 GPa; these values decreased when the jute proportion was higher. The thermal conductivity varied from 0.068 to 0.085 W·m−1·K−1. The main conclusion is that jute-cement-starch composite panels can be manufactured with physical, mechanical, and thermal properties that meet the European standards for use in the construction of buildings as partitions, interior divisions, and thermal insulators.
Barbara R Conway - One of the best experts on this subject based on the ideXlab platform.
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Plasticiser free 3d printed hydrophilic matrices quantitative 3d surface texture mechanical swelling erosion drug release and pharmacokinetic studies
Polymers, 2019Co-Authors: Zara Khizer, Muhammad Rouf Akram, Rai Muhammad Sarfraz, Jorabar Singh Nirwan, Samia Farhaj, Maria Yousaf, Tariq Hussain, Shan Lou, Peter Timmins, Barbara R ConwayAbstract:Hydroxypropyl methyl cellulose, HPMC, a hydrophilic polymer, is widely used for the development of extended release hydrophilic matrices and it is also considered as a good contender for the fabrication of 3D printing of matrix tablets. It is often combined with Plasticisers to enable extrusion. The aim of the current project was to develop plasticizer-free 3D printed hydrophilic matrices using drug loaded filaments prepared via HME to achieve an in vitro (swelling, erosion and drug release) and in vivo (drug absorption) performance which is analogous to hydrophilic matrix tablets developed through conventional approaches. Additionally, the morphology of the printed tablets was studied using quantitative 3D surface texture studies and the porosity calculated. Filaments were produced successfully and used to produce matrix tablets with acceptable drug loading (95–105%), mechanical and surface texture properties regardless of the employed HPMC grade. The viscosity of HPMC had a discernible impact on the swelling, erosion, HPMC dissolution, drug release and pharmacokinetic findings. The highest viscosity grade (K100M) results in higher degree of swelling, decreased HPMC dissolution, low matrix erosion, decreased drug release and extended drug absorption profile. Overall, this study demonstrated that the drug loaded (glipizide) filaments and matrix tablets of medium to high viscosity grades of HPMC, without the aid of Plasticisers, can be successfully prepared. Furthermore, the in vitro and in vivo studies have revealed the successful fabrication of extended release matrices.