The Experts below are selected from a list of 8631 Experts worldwide ranked by ideXlab platform
Julien Bras - One of the best experts on this subject based on the ideXlab platform.
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production of cationic nanofibrils of cellulose by twin screw extrusion
Industrial Crops and Products, 2019Co-Authors: Seema Saini, Valerie Meyer, Michel Petitconil, Julien BrasAbstract:Abstract Cationization of cellulose fibers introduces positives charges and thus decreases the energy consumption to produce cellulose nanofibrils (CNF), improves their quality and confers them antimicrobial properties. In this study, cationic CNF at 17 wt% solid content were produced for the first time using an energy efficient process: the twin-screw extrusion (TSE). The production was compared to the production of enzymatic CNF using the same mechanical treatment and the efficiency of Cationization was discussed. CNF produced were characterized using different techniques such as optical microscopy, atomic force microscopy, mechanical properties or transparency and finally classified using the quality index. Despite a slipping effect in the TSE which leads to intact residual fibers, highly transparent CNF with high Young’s modulus (10 GPa) and suitable quality index were obtained consuming only 1100 kW h/t. Activity of cationized CNF to limit bacteria proliferation has even been confirmed.
Alan G. Marshall - One of the best experts on this subject based on the ideXlab platform.
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Lithium Cationization for Petroleum Analysis by Positive Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
Energy & Fuels, 2014Co-Authors: Vladislav V. Lobodin, Ryan P. Rodgers, Priyanka Juyal, Amy M. Mckenna, Alan G. MarshallAbstract:Lithium Cationization can significantly extend the compositional range for analysis of petroleum components by positive electrospray ionization [(+) ESI], by accessing species that lack a basic nitrogen atom and, hence, are not seen by conventional (+) ESI that relies on protonation as the primary ionization mechanism. Here, various solvent compositions and lithium salts enabled us to optimize ionization by formation of lithium adducts ([M + Li]+), and the results are compared to production of [M + H]+ by conventional (+) ESI with formic acid. Lithium Cationization (+) ESI Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of Athabasca bitumen heavy vacuum gas oil (475–500 °C) and North and South American crude oils demonstrates considerable improvement over protonation for production of ions from compounds belonging to SxOy (SO, SO2, SO3, SO4, S2O, S2O2, etc.) heteroatom classes. Those compounds exhibit much higher affinity for lithium cation than for proton and yield abundant [M + L...
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silver Cationization for rapid speciation of sulfur containing species in crude oils by positive electrospray ionization fourier transform ion cyclotron resonance mass spectrometry
Energy & Fuels, 2014Co-Authors: Vladislav V. Lobodin, Ryan P. Rodgers, Priyanka Juyal, Amy M. Mckenna, Alan G. MarshallAbstract:Silver Cationization constitutes a complementary approach for analysis of petroleum components with positive-ion electrospray ionization (ESI) mass spectrometry and accesses species that lack a basic nitrogen atom and, hence, are not observed by conventional positive ESI. Four samples of different origin [Canadian bitumen, Canadian bitumen heavy vacuum gas oil (HVGO; 475–500 °C) and South American and Middle East heavy crude oils, all high in sulfur content] were used to study silver Cationization by (+) ESI. Cationization with Ag+ is essentially instantaneous and accesses hydrocarbons and nonpolar sulfur-containing heteroatom classes (e.g., Ss and SsOo), providing an attractive alternative to time-consuming derivatization by S-methylation to ionize sulfur-containing species. For each sample, we compare Ag+ Cationization (+) ESI to conventional (+) ESI with formic acid to promote ion formation. Other ionization methods, such as chemical ionization (CI), field desorption (FD), matrix-assisted laser desorpt...
Bruno Vergnes - One of the best experts on this subject based on the ideXlab platform.
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Preparation of Cationic Starches by Reactive Extrusion: Experiments and Modelling
2018Co-Authors: Françoise Berzin, Bruno VergnesAbstract:Starch is one of the most common polysaccharides from natural and renewable resources. It is increasingly used in place of synthetic polymers for industrial applications and can be chemically modified to obtain products having specific properties. For example, cationic starches are largely used in the paper industry. They are generally prepared using conventional batch reactors, but they can also be obtained using reactive extrusion. In this chapter, after a brief introduction to the twin-screw reactive extrusion process, experimental results of starch Cationization are presented. Then, a model based on flow simulation coupled to a kinetic equation is developed, allowing a clear understanding of the influence of the processing parameters on the extent of the Cationization reaction. This model, experimentally validated, is then used to solve optimization and scale-up problems.
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Optimization and scale-up of starch Cationization in a twin screw extruder
Polymer Engineering and Science, 2007Co-Authors: Françoise Berzin, Ahmed Tara, Bruno VergnesAbstract:In a previous work, a theoretical model for the Cationization of wheat starch in a modular self-wiping corotating twin screw extruder has been developed and experimentally validated. Our objective in the present article was to use this model in a first step to optimize the Cationization reaction on a laboratory scale extruder, and, in a second step, to extrapolate the results to an industrial scale extruder. We will show that the use of a theoretical model of reactive extrusion allowed us to define screw profiles and processing conditions according to the end-use properties of the desired product and the limits of the process. Based on the performances obtained at laboratory scale, it permitted also to predict the performances of an industrial production line.
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optimization and scale up of starch Cationization in a twin screw extruder
Polymer Engineering and Science, 2007Co-Authors: Françoise Berzin, Ahmed Tara, Bruno VergnesAbstract:In a previous work, a theoretical model for the Cationization of wheat starch in a modular self-wiping corotating twin screw extruder has been developed and experimentally validated. Our objective in the present article was to use this model in a first step to optimize the Cationization reaction on a laboratory scale extruder, and, in a second step, to extrapolate the results to an industrial scale extruder. We will show that the use of a theoretical model of reactive extrusion allowed us to define screw profiles and processing conditions according to the end-use properties of the desired product and the limits of the process. Based on the performances obtained at laboratory scale, it permitted also to predict the performances of an industrial production line. POLYM. ENG. SCI., 47:814‐823, 2007. a 2007 Society of Plastics Engineers
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Computation of starch Cationization performances by twin-screw extrusion
Polymer Engineering and Science, 2007Co-Authors: Françoise Berzin, Ahmed Tara, Lan Tighzert, Bruno VergnesAbstract:A theoretical model for the Cationization of plasticized wheat starch in a modular self-wiping co-rotating twin screw extruder was developed. Our objective was to build a model which would be able to predict the evolution of the Cationization reaction along the screws, in relation with the processing conditions and the geometry of the twin screw extruder. Based on previous studies on reactive extrusion modeling, the present model takes into account the interactions occurring between the flow conditions encountered in the extruder and the kinetics of the reaction. It allows one to predict the influence of operating parameters such as reagent concentrations, feed rate, screw speed, and barrel temperature on the reaction extent. Depending on conditions, degrees of substitution in the range 0.01-0.05 are obtained, with efficiencies between 30 and 90%. A good agreement is found between theoretical results and experimental measurements, allowing future use of the model for optimization and scale-up purposes.
Vladislav V. Lobodin - One of the best experts on this subject based on the ideXlab platform.
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Lithium Cationization for Petroleum Analysis by Positive Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
Energy & Fuels, 2014Co-Authors: Vladislav V. Lobodin, Ryan P. Rodgers, Priyanka Juyal, Amy M. Mckenna, Alan G. MarshallAbstract:Lithium Cationization can significantly extend the compositional range for analysis of petroleum components by positive electrospray ionization [(+) ESI], by accessing species that lack a basic nitrogen atom and, hence, are not seen by conventional (+) ESI that relies on protonation as the primary ionization mechanism. Here, various solvent compositions and lithium salts enabled us to optimize ionization by formation of lithium adducts ([M + Li]+), and the results are compared to production of [M + H]+ by conventional (+) ESI with formic acid. Lithium Cationization (+) ESI Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of Athabasca bitumen heavy vacuum gas oil (475–500 °C) and North and South American crude oils demonstrates considerable improvement over protonation for production of ions from compounds belonging to SxOy (SO, SO2, SO3, SO4, S2O, S2O2, etc.) heteroatom classes. Those compounds exhibit much higher affinity for lithium cation than for proton and yield abundant [M + L...
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silver Cationization for rapid speciation of sulfur containing species in crude oils by positive electrospray ionization fourier transform ion cyclotron resonance mass spectrometry
Energy & Fuels, 2014Co-Authors: Vladislav V. Lobodin, Ryan P. Rodgers, Priyanka Juyal, Amy M. Mckenna, Alan G. MarshallAbstract:Silver Cationization constitutes a complementary approach for analysis of petroleum components with positive-ion electrospray ionization (ESI) mass spectrometry and accesses species that lack a basic nitrogen atom and, hence, are not observed by conventional positive ESI. Four samples of different origin [Canadian bitumen, Canadian bitumen heavy vacuum gas oil (HVGO; 475–500 °C) and South American and Middle East heavy crude oils, all high in sulfur content] were used to study silver Cationization by (+) ESI. Cationization with Ag+ is essentially instantaneous and accesses hydrocarbons and nonpolar sulfur-containing heteroatom classes (e.g., Ss and SsOo), providing an attractive alternative to time-consuming derivatization by S-methylation to ionize sulfur-containing species. For each sample, we compare Ag+ Cationization (+) ESI to conventional (+) ESI with formic acid to promote ion formation. Other ionization methods, such as chemical ionization (CI), field desorption (FD), matrix-assisted laser desorpt...
K. P. Madhusudanan - One of the best experts on this subject based on the ideXlab platform.
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Effect of metal Cationization on the tandem mass spectra of glycosyl dithioacetals.
Journal of mass spectrometry : JMS, 2005Co-Authors: K. P. Madhusudanan, Brijesh Kumar, Pallavi Tiwari, Soni Kamlesh Madhusudan, Anup Kumar MisraAbstract:The effect of metal Cationization on the tandem mass spectra of glycosyl dithioacetals of glucose, mannose, galactose, rhamnose, arabinose and xylose was studied by electrospray ionization mass spectrometry under ammonium and metal (Li, Na, Ag and Cu) ion Cationization conditions. The ammonium-cationized glycosyl dithioacetals fragment by loss of ammonia followed by either two molecules of EtSH or one molecule of EtSH and one molecule of H2O. Lithium Cationization leads to additional eliminations such as EtSEt and EtSSEt and C-C cleavages. Elimination of EtSH is not observed under sodium Cationization. Silver Cationization, on the other hand, leads to additional fragmentations involving the elimination of silver as AgOH and AgSEt. Copper Cationization results in adducts where copper has undergone a change of oxidation state from II to I. Li+, Ag+ and Cu+ Cationization seem to favour cyclization resulting in elimination of EtSH. However, the mechanisms seem to be differently affected by different metal ions. Li+ and Ag+ Cationization appear to be non-specific and favour cyclization involving C2-, C4- and C5-hydroxyl hydrogens, whereas Cu+ Cationization seems to favour cyclization involving C4-hydroxyl hydrogen.
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Effect of alkali metal Cationization and multiple alkali metal exchange on the collision-induced dissociation of loganic acid studied by electrospray ionization tandem mass spectrometry
Rapid communications in mass spectrometry : RCM, 2000Co-Authors: K. P. Madhusudanan, Kanwal Raj, Amiya Prasad BhaduriAbstract:Under electrospray ionization conditions loganic acid undergoes alkali metal (Li, Na and K) exchange and alkali metal Cationization. Multiple exchanges of up to four alkali metal ions are observed. Different populations of metal exchanged species are produced during electrospray ionization. Collision-induced dissociation of ammonium cationized species is compared with that of metal cationized species to study the effect of metal Cationization. Glycosidic cleavage and ring cleavages of aglycone and sugar moieties are the major fragmentation pathways observed during collision-induced dissociation. The fragmentations of the highly metal exchanged species indicate the opening of the pyran ring. Collision-induced dissociation of the various metal exchanged and metal cationized species also reveals the nature of the different populations. Copyright 2000 John Wiley & Sons, Ltd.
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Characterization of iridoids by fast atom bombardment mass spectrometry followed by collision‐induced dissociation of [M + Li]+ ions
Journal of mass spectrometry : JMS, 2000Co-Authors: K. P. Madhusudanan, Kanwal Raj, Vijayvitthal T. Mathad, Shefali, Amiya Prasad BhaduriAbstract:Fast atom bombardment mass spectra of a series of naturally occurring and synthetically modified iridoid glycosides were studied using lithium Cationization and collision-induced dissociation of the resulting [M+Li]+ ions. Lithium Cationization leads to the unambiguous determination of the molecular masses of these compounds. Collision-induced dissociation of the lithiated molecular ions give valuable structural information regarding the nature of the substituent on both the aglycone and the sugar moieties. The characteristic fragmentation pathways identified are (1) elimination of neutral molecules comprising the substituents on either the aglycone or sugar moieties, (2) formation of lithiated aglycone and their fragment ions, (3) formation of lithiated sugar and their fragment ions, (4) fragmentation corresponding to the cleavage of the aglycone or sugar ring and (5) fragmentation characteristic of the substituents present in either the aglycone or sugar parts of the molecule. Elimination of two acyloxy radicals from the lithiated molecular ion is a characteristic fragmentation in the case of acyloxy derivatives.