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A kinetic model for a single step biodiesel production from a high free fatty acid (FFA) biodiesel feedstock over a solid heteropolyacid catalyst

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Green Energy & Environment 2019年第3期4卷 328-341页

作者： Aashish Gaurav stéphane dumas Chau T.Q.Mai Flora T.T.Ng Department of Chemical Engineering University of Waterloo

Production of biodiesel from yellow grease(waste cooking oil and waste animal fats) is fast emerging as a promising alternative to address the twin challenges before the biodiesel industry today-fluctuation in prices of vegetable oil and the food versus fuel debate. Yellow grease has a high percentage of free fatty acids(FFA) and proves to be an unsuitable feedstock for biodiesel production from commercially viable alkalicatalyzed production systems due to saponification problems.'Green' methodologies based on heterogeneous solid acid catalyzed reactions have the potential to simultaneously promote esterification and transesterification reactions of yellow grease to produce biodiesel without soap formation and offer easy catalyst separation without generation of toxic streams. This paper presents kinetic studies for the conversion of model yellow grease feeds to biodiesel using a heteropolyacid supported on alumina(HSiW/Al2O3) using a batch autoclave. Three model yellow grease feeds were prepared using canola oil with added FFA such as palmitic, oleic and linoleic acid. A pseudo homogeneous kinetic model for the parallel esterification and transesterification was developed. The rate constants and activation parameters for esterification and transesterification reactions for the model yellow grease feeds were determined. The rate constants for esterification are higher than the transesterification rate constants. The kinetic model was validated using the experimental biodiesel data obtained from processing a commercial yellow grease feed. The kinetic model could be used to design novel processes to convert various low-value waste oils, fats and non-food grade oils to sustainable biodiesel.

关键词： Yellow grease Canola oil Free fatty acids Heteropolyacid Kinetics for esterification and transesterification

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statistical physics in QCD evolution towards high energies

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Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 1-32页

作者： MUNIER stphane Centre de physique thorique ′Ecole PolytechniqueCNRS Palaiseau France

The concepts and methods used for the study of disordered systems have proven useful in the analysis of the evolution equations of quantum chromodynamics in the high-energy regime: Indeed, parton branching in the semi-classical approximation relevant at high energies and at a fixed impact parameter is a peculiar branching-diffusion process, and parton branching supplemented by saturation effects(such as gluon recombination) is a reaction-diffusion process. In this review article, we first introduce the basic concepts in the context of simple toy models, we study the properties of the latter, and show how the results obtained for the simple models may be taken over to quantum chromodynamics.

关键词： quantum chromodynamics color dipole model color glass condensate stochastic fronts traveling waves reaction-diffusion

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Comparative study of abrasion via microindentation and microscratch tests of reinforced and unreinforced lamellar cast iron

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Friction 2019年第5期7卷 457-465页

作者： Mohammed MENDAS stéphane BENAYOUN Laboratory of Rheology and Mechanics(LRM) Hassiba Benbouali University of ChlefHay Essalem Chlef BP151(02000)Algeria LTDS UMR CNRS5513Ecole Centrale de LyonUniversity of LyonEcully Cedex F-69134France

This study compares micro-abrasive wear in two kinds of grey cast iron. Classical lamellar cast iron with fully pearlitic matrix(FGL1) and lamellar micro-alloyed cast iron with phosphorus and boron(FGL2) are used. FGL2 has a fully pearlitic matrix reinforced by the hard phosphorus eutectic phase. The microstructures of these two types of iron are mechanically characterized using nanoindentation tests. Vickers microindentation and microscratch tests are also performed on these iron samples. The indent and scratch images obtained via scanning electron microscopy were used to compare the scratch damage to the two kinds of iron. The friction coefficient is discussed in terms of applied load, indenter attack angle, and scratch damage. Nanoindentation tests show an improvement in graphite’s mechanical properties and an increase in the matrix hardness of the FGL2, relatively to FGL1. The same damage forms for both microindentation and microscratch testing were observed for the two iron samples. However, cracking of the hard phase is observed in FGL2. The results show that the scratching of the micro-alloyed iron(FGL2) leads to less matrix damage and to an extended microploughing wear mechanism. However, at low normal load, the reinforcement of the matrix can increase the friction coefficient.

关键词： grey cast iron indentation microscratch abrasive wear

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Solar chemical looping reforming of methane combined with isothermal H2O/CO2 splitting using ceria oxygen carrier for syngas production

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Journal of Energy Chemistry 2020年第2期29卷 60-72页

作者： Srirat Chuayboon stéphane Abanades Sylvain Rodat Processes Materials and Solar Energy LaboratoryPROMES-CNRSFont-Romeu 66120France Department of Mechanical Engineering King Mongkut's Institute of Technology LadkrabangPrince of Chumphon CampusChumphon 86160Thailand Universite Grenoble Alpes Le-Bourget-du-Lac F-73375France CEA-LJTEN Laboratoire des Systemes Solaires Haute Temperature(LSHT) Grenoble F-38054France

The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H2 O/CO2 at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants(ceria packed powder, ceria packed powder mixed with inert Al2 O3 particles, and ceria reticulated porous foam) and operating parameters(methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry(δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH4 and H2 O(or CO2). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion,and reactor performance. Increasing both CH4 concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH4 cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.

关键词： Chemical looping Methane reforming Ceria structure Concentrated solar power Syngas production H2O/CO2 splitting

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Conversion of the refractory ammonia and acetic acid in catalytic wet air oxidation of animal byproducts

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Journal of Environmental Sciences 2011年第3期23卷 520-528页

作者： Virginie Fontanier Sofiane Zalouk stéphane Barbati Aix-Marseille Universite's-CNRS (UMR 6264)-Laboratoire de Chimie Provence:quipe Chimie de l'Environnement Continental-3 Place Victor Hugo (case 29)-13331 Marseille cedex 3France

Wet air oxidation （WAO） and catalytic wet air oxidation （CWAO） of slaughtered animal byproducts （ABPs） were investigated. Two step experiment was carried out consisting of a non-catalysed WAO run followed by a CWAO run at 170-275 ℃, 20 MPa, and reaction time 180 min. The WAO （lst step） of sample （5 g/L total organic carbon （TOC）） yielded （82.0 ±4）% TOC removal and （78.4 ± 13.2）% conversion of the initial organic-N into NH4＋-N. Four metal catalysts （Pd, Pt, Rh, Ru） supported over alumina have been tested in catalytic WAO （2nd step） at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid. It was found that the catalysts Ru, Pt, and Rh had significant effects on the TOC removal （95.1%, 99.5% and 96.7%, respectively） and on the abatement of ammonia （93.4%, 96.7% and 96.3%, respectively） with high nitrogen selectivity. The catalyst Pd was found to have the less activity while Pt had the best performance. The X-Ray diffraction analysis showed that the support of catalyst was not stable under the experimental conditions since it reacted with phosphate present in solution. Nitrite and nitrate ions were monitored during the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with the results obtained from the literature for ideal solutions of ammonia.

关键词： wet oxidation, heterogeneous catalysis animal byproducts acetic acid ammonia, nitrite nitrate

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New perspectives for investigating respiratory failure induced by cervical spinal cord injury

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Neural Regeneration Research 2014年第22期9卷 1949-1951页

作者： Marcel Bonay stéphane Vinit Université de Versailles Saint-Quentin-en-Yvelines Unité End:icapUFR des Sciences de la Santé–Simone Veil78180 Montigny-le-BretonneuxFrance Service de Physiologie-Explorations Fonctionnelles H?pital Ambroise Paré Assistance Publique-H?pitaux de Paris(AP-HP)Groupe Hospitalier Paris Ile-de-France Ouest92104 BoulogneBillancourtFrance

Traumatic cervical spinal cord injury （SCI）, with an annual incidence of 12,000 new cases in USA （NSCISC 2013）, causes devastating locomotor and respiratory paralysis and unfortunately compromises the human patient＇s lifespan. The severity of the injury depends on the degree and the extent of the initial trauma. In fact, respiratory failure is the leading cause of mortality following upper cervical SCI. However, 80% of the injuries are incomplete, allowing some modest spontaneous recovery. To date, no effective treatment is available in order to restore the loss of function.

关键词： SCI New perspectives for investigating respiratory failure induced by cervical spinal cord injury CPP

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Late-entry commercial thinning effects on Pinus banksiana:growth, yield, and stand dynamics in Québec, Canada

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Journal of Forestry Research 2019年第1期30卷 95-106页

作者： Martin-Michel Gauthier stéphane Tremblay Ministère des Forêts de la Faune et des Parcs du Québec Natural Resources Canada Canadian Forest Service

We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.

关键词： Jack pine Commercial thinning stand yield Succession Delayed senescence Tree regeneration

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Magnesium sulfate and fetal neuroprotection: overview of clinical evidence

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Neural Regeneration Research 2018年第12期13卷 2044-2049页

作者： Clément Chollat stéphane Marret Institut National de la Santé et de la Recherche Médicale U1245 Genetics and Pathophysiology of Neurodevelopmental Disorders Team 4Neovasc Institute of Research and Innovation in Biomedicine Rouen School of Medicine Normandy University Department of Neonatal Intensive Care Port Royal University Hospital Department of Neonatal Pediatrics and Intensive Care and Neuropediatrics Charles-Nicolle University Hospital

Antenatal administration of magnesium sulfate is an important part of the neuroprotective strategy for preterm infants. strong evidence from five randomized controlled trials and five meta-analyses has demonstrated that magnesium sulfate, when administered before preterm delivery, significantly reduces the risk of cerebral palsy at two years. Through secondary analyses of randomized controlled trials and other original clinical studies, this state-of-the-art review highlights the absence of serious adverse effects in both pregnant women and neonates, as well as the impact of maternal body mass index and preeclamptic status on the maternal and neonatal magnesium levels, which could influence the magnitude of the neuroprotective effect. Although antenatal magnesium sulfate is a cost-effective strategy, some practice surveys have demonstrated that the use of magnesium sulfate is not sufficient and that its use is heterogeneous, differing among different maternity wards. Since 2010, an increasing number of obstetrical societies have recommended its use to improve the neurological outcomes of preterm infants, especially the International Federation of Gynecology and Obstetrics and World Health Organization in 2015, and France in 2017. Considering the neuroprotective impact of magnesium sulfate when administered before delivery, postnatal administration should be considered, and its effects should be assessed using randomized controlled trials.

关键词： magnesium sulfate preterm birth neuroprotection cerebral palsy neurodevelopment international recommendations clinical studies meta-analysis preeclampsia cost-effectiveness

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Hepatitis C virus: Virology, diagnosis and management ofantiviral therapy

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World Journal of Gastroenterology 2007年第17期13卷 2461-2466页

作者： stéphane Chevaliez Jean-Michel Pawlotsky French National Reference Center for Viral Hepatitis B C and deltaDepartment of Virology & INSERM U841 Henri Mondor Hospital University of Paris XII Créteil France

Hepatitis C virus (HCV) infects approximately 170 million individuals worldwide. Prevention of HCV infection complications is based on antiviral therapy with the combination of pegylated interferon alfa and ribavirin. The use of serological and virological tests has become essential in the management of HCV infection in order to diagnose infection, guide treatment decisions and assess the virological response to antiviral therapy. Anti- HCV antibody testing and HCV RNA testing are used to diagnose acute and chronic hepatitis C. The HCV genotype should be systematically determined before treatment, as it determines the indication, the duration of treatment, the dose of ribavirin and the virological monitoring procedure. HCV RNA monitoring during therapy is used to tailor treatment duration in HCV genotype 1 infection, and molecular assays are used to assess the end-of-treatment and, most importantly the sustained virological response, i.e. the endpoint of therapy.

关键词： Hepatitis C virus serological tests HepatitisC virus genotype HCV RNA quantification Interferon alpha Ri-bavirin-

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Benford or Not Benford:A Systematic But Not Always Well-Founded Use of an Elegant Law in Experimental Fields

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Communications in Mathematics and statistics 2020年第2期8卷 167-201页

作者： stéphane Blondeau Da Silva XLIM-Mathis UMR no 7252 CNRS-Universitéde Limoges123Avenue Albert Thomas87060 LimogesFrance

In this paper,we will propose a way to accurately model certain naturally occurring collections of *** this proposed model,the proportion of d as leading digit,d∈[1,9],in data is more likely to follow a law whose probability distribution is determined by a specific upper bound,rather than Benford’s Law,as one might have *** probability distributions fluctuate nevertheless around Benford’s *** peculiar fluctuations have often been observed in the literature in such data sets(where the physical,biological or economical quantities considered are upper bounded).Knowing beforehand the value of this upper bound enables to find,through the developed model,a better adjusted law than Benford’s one.

关键词： Benford’s Law Leading digit Experimental data

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