246 research outputs found
Introduction to probabilistic concurrent systems
Get PDFThe first part of the paper is an introduction to the theory of probabilistic
concurrent systems under a partial order semantics. Key definitions and results
are given and illustrated on examples. The second part includes contributions.
We introduce deterministic concurrent systems as a subclass of concurrent
systems. Deterministic concurrent system are "locally commutative'" concurrent
systems. We prove that irreducible and deterministic concurrent systems have a
unique probabilistic dynamics, and we characterize these systems by means of
their combinatorial properties.Comment: Extended version of the Petri Net 2021 conference paper
arXiv:2008.07233 "Deterministic concurrent systems" by the same author. 32
pages, 9 figures, 17 reference
Characterization of processing-induced arabinoxylan modifications and their effect on the in vitro fermentation by gut microbiota
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Towards a better understanding of the molecular mechanism underlying weak interactions between soluble dietary fibers and small molecules
No full textComplementary Sample Preparation Strategies for Analysis of Cereal β-Glucan Oxidation Products by UPLC-MS/MS
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Complementary Sample Preparation Strategies for Analysis of Cereal β-Glucan Oxidation Products by UPLC-MS/MS
No full textThe oxidation of cereal (1→3,1→4)-β-D-glucan can influence the health promoting and technological properties of this linear, soluble homopolysaccharide by introduction of new functional groups or chain scission. Apart from deliberate oxidative modifications, oxidation of β-glucan can already occur during processing and storage, which is mediated by hydroxyl radicals (HO•) formed by the Fenton reaction. We present four complementary sample preparation strategies to investigate oat and barley β-glucan oxidation products by hydrophilic interaction ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), employing selective enzymatic digestion, graphitized carbon solid phase extraction (SPE), and functional group labeling techniques. The combination of these methods allows for detection of both lytic (C1, C3/4, C5) and non-lytic (C2, C4/3, C6) oxidation products resulting from HO•-attack at different glucose-carbons. By treating oxidized β-glucan with lichenase and β-glucosidase, only oxidized parts of the polymer remained in oligomeric form, which could be separated by SPE from the vast majority of non-oxidized glucose units. This allowed for the detection of oligomers with mid-chain glucuronic acids (C6) and carbonyls, as well as carbonyls at the non-reducing end from lytic C3/C4 oxidation. Neutral reducing ends were detected by reductive amination with anthranilic acid/amide as labeled glucose and cross-ring cleaved units (arabinose, erythrose) after enzyme treatment and SPE. New acidic chain termini were observed by carbodiimide-mediated amidation of carboxylic acids as anilides of gluconic, arabinonic, and erythronic acids. Hence, a full characterization of all types of oxidation products was possible by combining complementary sample preparation strategies. Differences in fine structure depending on source (oat vs. barley) translates to the ratio of observed oxidized oligomers, with in-depth analysis corroborating a random HO•-attack on glucose units irrespective of glycosidic linkage and neighborhood. The method was demonstrated to be (1) sufficiently sensitive to allow for the analysis of oxidation products also from a mild ascorbate-driven Fenton reaction, and (2) to be specific for cereal β-glucan even in the presence of other co-oxidized polysaccharides. This opens doors to applications in food processing to assess potential oxidations and provides the detailed structural basis to understand the effect oxidized functional groups have on β-glucan's health promoting and technological properties
Complementary Sample Preparation Strategies for Analysis of Cereal β-Glucan Oxidation Products by UPLC-MS/MS
No full textISSN:2296-264
Production of hydrogen from water using a thermochemical copper-chlorine cycle
No full textA system for producing hydrogen gas from water decomposition using a thermochemical CuCl cycle, the improvement comprising the use of an insulated hydrogen production reactor comprising a reaction chamber and a separation chamber; the reaction chamber having a hydrogen chloride gas inlet and a solid copper inlet; one or more levels provided in the reaction chamber, the number of which is dependant on production scale and pressure drop; each level comprising a perforated plate with associated filter media, the perforations of the plate and media being of decreasing size from top to bottom of the reaction chamber, and being sized to permit downward flow of the hydrogen gas and molten CuCl products, as well as the HCL gas reactant, and to prevent entrainment of solid copper in the molten CuCl; the separation chamber being located below the reaction chamber and being of greater cross section than the reaction chamber and comprising a first hydrogen removal and entrained copper removal zone and a second molten CuCl removal zone; removal of the reaction products being controlled so as to substantially decrease the amount of entrained copper in the molten CuCl; and the first zone having outlets for removal of hydrogen gas and entrained copper particles, with the second zone having an outlet for removal of molten CuCl
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