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Mixing assessment by chemical probe
Charbel Habchi,Hassan Peerhossaini,Thierry Lemenand,Dominique Della Valle,Mahmoud Khaled,Ahmed Elmarakbi 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Quantification of micro-mixing is a fundamental issue in industrial chemical processes. Local mixing that is not ‘‘fast enough’’ compared with the reaction kinetics reduces the selectivity of the reaction. Micro-mixing can be characterized by chemical probe methods based on observation of a local chemical reaction that results from the competition between turbulent mixing at micro-scales and the reaction kinetics. However, real-world experimental conditions rarely comply with the grounding assumptions of this method. Starting from physical considerations, the present study aims to establish some guidelines for obtaining quantitative information from the chemical probe and for improving the accuracy of the method by an adaptive protocol. For the first aspect, an analytical approach is proposed to define the validity domain based on analysis of the turbulent time scales. For the second purpose, a novel experimental procedure is suggested that entails targeting the concentrations of the chemical species that can provide the optimal conditions for a relevant use of the chemical probe.
C. Bilel,M.M. Habchi,A. Ben Nasr,I. Guizani,A. Rebey,B. El Jani 한국물리학회 2016 Current Applied Physics Vol.16 No.3
We present a self-consistent calculation combined with the 16-band anticrossing model in order to investigate the electronic and optical properties of n-doped GaNAsBi/GaAs multiple-QWs operating at 1.55 mm. Optoelectronic features of these quantum structures seem advantageous for the design of photodetector devices. We have found that doping induces a blue shift of the fundamental transition energy for the uncoupled double-QWs with the barrier width Lb ¼ 12 nm. This transition energy shows a red shift when the doped DQWs are coupled (Lb ¼ 2 nm). An applied electric field favors further this shift. The coupling and Stark effects on the spatial distribution of confined electrons density are discussed. The absorption coefficient for the coupled 4 nm GaN.04As.89Bi.07/GaAs DQWs is enhanced compared to the undoped or uncoupled DQWs. Finally, we have examined the dependence of the absorption magnitude on the doping density and electric field for different values of wells number.
M. KHALED,M. G. ELRAB,C. HABCHI,A. ALSHAER,A. ELMARAKBI,F. HARAMBAT,H. PEERHOSSAINI 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.2
The thermal soak phase of a vehicle results from driving the vehicle at high load followed by shutting off the engine. The present work deals with the analysis and modeling of the thermal soak phase of a vehicle through temperature and heat flux measurements. Measurements are carried out on a passenger vehicle in wind tunnel S4 of Saint-Cyr-France. The underhood is instrumented by alsmot 120 surface and air thermocouples and 20 fluxmeters. Measurements are performed for three thermal functioning conditions, with the engine in operation and the front wheels positioned on the test facility with power-absorption controlled rollers. It was found that in thermal soak the temperature of certain components can increase by almost 80℃ (pre-catalyst) and that of air zones by alsmot 40℃ (crawl area). These components correspond to areas that heat up after stopping the engine for 3 to 24 minutes, depending on their position in the underhood and on the thermal operating point considered.
Chemical and mechanistic analysis of photodynamic inhibition of Alzheimer's β-amyloid aggregation
Ahn, Minkoo,Lee, Byung Il,Chia, Sean,Habchi, Johnny,Kumita, Janet R.,Vendruscolo, Michele,Dobson, Christopher M.,Park, Chan Beum The Royal Society of Chemistry 2019 Chemical communications Vol.55 No.8
<P>The self-assembly of the beta-amyloid peptide (Aβ) into amyloid aggregates is a central phenomenon associated with Alzheimer's disease. Here, we report chemical modifications of key amino acid residues of Aβ42 (Y10, H13, H14, and M35) by photoexcited thioflavin-T (ThT), a fluorescent probe of amyloid structure. The quantitative chemical kinetics analysis shows that the oxidized monomer species does not self-assemble, nor perturb the aggregation kinetics of non-oxidized Aβ42.</P>
Chitin oligomers and monomers production by coupling g radiation and enzymatic hydrolysis
M. Dziril,H. Grib,H. Laribi-Habchi,N. Drouiche,N. Abdi,H. Lounici,A. Pauss,N. Mameri 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-
The main purpose of this study was the chitin enzymatic hydrolysis enhancement by a pretreatment, consisting of chitin exposure to gamma radiation at several doses, ranging from 15 kGy to 210 kGy. The solid chitin molecular weight reduction achieved by Co-60 gamma rays treatment reached a 90% rate at the t used, with a dose of 210 kGy. The partial depolymerization of chitin was realized by irradiation allowing an enzyme affinity increase toward this substrate. The monomers and oligomers obtained from their radiated chitin production rate were almost 100%. It was also demonstrated that the NAG production by enzymatic hydrolysis of irradiated chitin at 210 Gy follows Michaelis–Menton kinetics.