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231.
Derrouz Hatim Cabri Alberto Ait Abdelali Hamd Oulad Haj Thami Rachid Bourzeix François Rovetta Stefano Masulli Francesco 《Neural computing & applications》2022,34(7):5561-5576
Neural Computing and Applications - Intelligent Transportation Systems (ITS) are the most widely used systems for road traffic management. The vehicle type classification (VTC) is a crucial ITS... 相似文献
232.
Rachid Tir Paresh C. Dutta Ahmed Yacine Badjah‐Hadj‐Ahmed 《European Journal of Lipid Science and Technology》2012,114(12):1427-1438
This study highlights the effect of solvent polarity on the yield (Y%) and properties of oil extracted from Algerian sesame seeds. Extractions were carried out under Soxhlet conditions with the following solvents: hexane (Hx), ethanol (Eth), acetone (Ac), dichloromethane (Di), isopropanol (Iso), hexane:isopropanol (Hx:Iso), and chloroform:methanol (Chf:Me). The sesame oil yield obtained using different solvents ranged from 28.86 to 52.83%. Fatty acids and sterols analyses were performed by GC on capillary column. γ‐Tocopherol was the major tocochromanol compound detected by HPLC‐fluorescence. Fourteen fatty acids were identified, with the predominance of oleic and linoleic acids. The main sterol in sesame oil was β‐sitosterol, followed by stigmasterol, campesterol, and Δ5‐avenasterol which were present in lower concentrations. High correlations were found between arachidic, gadoleic, behenic, and lignoceric acids concentrations; these results were explained by the metabolic biosynthesis pathway of the biologically active long‐chain PUFA by successive elongation and desaturation. Principal component analysis (PCA) of the data obtained from sesame oil composition enabled an easy comparison of the different extraction solvents, and correlated their properties with the most characteristic components of the extracted oils with a view to understand solvent–oil interaction, and to establish the effects of extracting solvent on such oil composition. Practical applications: This study showed that the choice of solvent depends largely on the desired fraction to be extracted. Sesame oil was better extracted with less‐polar solvents but membrane‐associated lipids are more polar and require polar solvents capable of breaking hydrogen bonds or electrostatic forces. Owing to the differences in solvent capacity, the fatty acids, sterols, and tocopherols extracted along with the oil vary, leading to differences in the quality of the extracted oil. The results obtained in this study could be applied in industrial extraction to encourage the use of alternative extraction solvents. 相似文献
233.
Marusczak N Larose C Dommergue A Yumvihoze E Lean D Nedjai R Ferrari C 《The Science of the total environment》2011,409(19):3949-3954
Surface snow samples were collected weekly from the 31st of December 2008 to the 21st of June 2009 from Lake Bramant in the French Alps. Total mercury (THg), total dissolved mercury (THgD), methylmercury (MeHg) and particle distributions in surface snow were analyzed. Results showed that THg concentrations, MeHg concentrations and particle load increased with snow surface temperature, which is an indicator of rising temperatures as the season progresses. Significant correlations between MeHg and snow surface temperature and MeHg and total particles greater than 10 μm were observed. This suggests that the MeHg found in the snow originates from atmospheric deposition processes rather than in situ snowpack sources. This study suggests that an important post-winter atmospheric deposition of MeHg and THg occurs on summital zones of the French Alps and it is likely that this contamination originates from the surrounding valleys. 相似文献
234.
Nassim Hallal Rachid Bougdal Wahiba Bensafia 《Bulletin of Engineering Geology and the Environment》2013,72(3-4):477-483
Underground work’s constructions and design techniques depend closely on the geological environment. The properties of the rock mass influence directly on the various steps of their realization so that geological and geotechnical studies become an absolute necessity to characterize the rock mass and to control the imposed constraints. At the end, we can conclude that the present work aims to define the geological and geotechnical conditions of the drilled rock mass; it consists mainly in determining the nature and the structure of the rock mass to cross, in addition to determining the rock mass stability and the reinforcement works. The route of the tunnel Aokas (Béjaïa) crosses a fractured limestone, where the karstification phenomenon is well developed and the best example being “fairy caves” contiguous on the old tunnel road in the NR 09. The two tunnel heads are located at the foot of two towering cliffs. All these characteristics make the tunnel in precarious potential stability. The detailed geological study allowed to determinate that the tunnel crosses through a karstified dolomitic limestone of the Babor’s chain of the lower Jurassic age, and a geotechnical study allowed a characterization of this rock mass regarding fracturing, mechanical and physical characteristics and led finally to a geomechanical classification. The stability of the tunnel is ensured by a strong support system. 相似文献
235.
Nazha Lakram Ikram Mercha El Haj El Maadoudi Rachid Kabbour Ahmed Douaik Abdelah El Housni 《The International journal of environmental studies》2013,70(5):815-826
Goat’s milk is an excellent source of antioxidants that resist oxidative stress. This paper reports on a study of Alpine goats, showing that introducing detoxified Argane press cake (DAPC) into their diet affected the antioxidant activity and polyphenol compounds in their milk during lactation. The results showed that the bioactive compounds of goat milk vary significantly (p < 0.001) depending on both their feed and milk lactation stage. The milk samples obtained from goats fed DAPC ranked highest total phenolic content, flavonoids, and DPPH(1,1-diphenyl-2-picrylhydrazyl) assays (367.91 ± 102.17 mg GAE/g of milk dry matter [DM], 120.76 ± 24.21 mg QE/g of milk DM, and 71.19 ± 2.84%, respectively) compared to milk samples collected from goats fed a diet including non-detoxified Argane press cake (289.03 ± 104.42 mg GAE/g of milk DM, 105.72 ± 13.60 mg QE/g of milk DM, and 64.22 ± 2.45%, respectively) and milk samples from goats fed a local diet (179.26 ± 81.28 mg GAE/g of milk DM, 89.86 ± 17.83 mg QE/g of milk DM, and 61.57 ± 5.08%, respectively). Additionally, the data revealed that including DAPC in the goat diet offers a good method for raising the amounts of total phenolic compounds and total flavonoids, with antioxidant activity in goat’s milk. 相似文献
236.
Rachid Tiberkak Mourad Bachene Said Rechak 《Journal of Mechanical Science and Technology》2014,28(6):2243-2252
The dynamic response of cracked isotropic plates subjected to impact loading is studied in this paper. The impact properties of cracked plate are compared with the virgin ones to predict the eventual presence of discontinuities in plates. The extended finite element method (X-FEM) is employed in the mathematical modeling of the impact problem, wherein the effects of shear deformation is considered. Conventional finite element without any discontinuity is initially conducted in the numerical implementation. Enriched functions are then added to the nodal displacement field for element nodes that contain cracks. The effects of crack length and crack position on contact force and on plate deflection are analyzed. Results show that the maximal contact force decreases as the deflection increases with increasing crack length a. The effect of crack position on the dynamic response is less pronounced when the crack is near the fixed end. 相似文献
237.
Abdoulkader Ali Mohamed Slim Salhi Souhir Abid Rachid El Gharbi Alain Fradet 《应用聚合物科学杂志》2014,131(15)
A series of random polyesteramides (PEAs) based on ε‐caprolactone and glycine were synthesized by a direct melt polycondensation method. Their structure was fully characterized by NMR spectroscopy. High molar mass PEAs were obtained for glycine contents lower than 15 mol‐%. The resulting copolymers are semi‐crystalline and present increasing glass transition temperatures but decreasing melting points at increasing glycine contents. Some of these PEAs exhibit better thermal stability and higher Young's modulus and ultimate tensile strength than PCL homopolymer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40573. 相似文献
238.
Highly Efficient Enzymatic Synthesis of 2-Monoacylglycerides and Structured Lipids and their Production on a Technical Scale 总被引:1,自引:0,他引:1
We report here a two-step process for the high-yield enzymatic synthesis of 2-monoacylglycerides (2-MAG) of saturated as well
as unsaturated fatty acids with different chain lengths. The process consists of two steps: first the unselective esterification
of fatty acids and glycerol leading to a triacylglyceride followed by an sn1,3-selective alcoholysis reaction yielding 2-monoacylglycerides. Remarkably, both steps can be catalyzed by lipase B from
Candida antarctica (CalB). The whole process including esterification and alcoholysis was scaled up in a miniplant to a total volume of 10 l.
With this volume, a two-step process catalyzed by CalB for the synthesis of 1,3-oleoyl-2-palmitoylglycerol (OPO) using tripalmitate
as starting material was established. On a laboratory scale, we obtained gram quantities of the synthesized 2-monoacylglycerides
of polyunsaturated fatty acids such as arachidonic-, docosahexaenoic- and eicosapentaenoic acids and up to 96.4% of the theoretically
possible yield with 95% purity. On a technical scale (>100 g of product, >5 l of reaction volume), 97% yield was reached in
the esterification and 73% in the alcoholysis and a new promising process for the enzymatic synthesis of OPO was established. 相似文献
239.
Simunovic V Zapp J Rachid S Krug D Meiser P Müller R 《Chembiochem : a European journal of chemical biology》2006,7(8):1206-1220
Myxococcus xanthus DK1622 is shown to be a producer of myxovirescin (antibiotic TA) antibiotics. The myxovirescin biosynthetic gene cluster spans at least 21 open reading frames (ORFs) and covers a chromosomal region of approximately 83 kb. In silico analysis of myxovirescin ORFs in conjunction with genetic studies suggests the involvement of four type I polyketide synthases (PKSs; TaI, TaL, TaO, and TaP), one major hybrid PKS/NRPS (Ta-1), and a number of monofunctional enzymes similar to the ones involved in type II fatty-acid biosynthesis (FAB). Whereas deletion of either taI or taL causes a dramatic drop in myxovirescin production, deletion of both genes (DeltataIL) leads to the complete loss of myxovirescin production. These results suggest that both TaI and TaL PKSs might act in conjunction with a methyltransferase, reductases, and a monooxygenase to produce the 2-hydroxyvaleryl-S-ACP starter that is proposed to act as the biosynthetic primer in the initial condensation reaction with glycine. Polymerization of the remaining 11 acetates required for lactone formation is directed by 12 modules of Ta-1, TaO, and TaP megasynthetases. All modules, except for the first module of TaL, lack cognate acyltransferase (AT) domains. Furthermore, deletion of a discrete tandem AT-encoded by taV-blocks myxovirescin production; this suggests an "in trans" mode of action. To embellish the macrocycle with methyl and ethyl moieties, assembly of the myxovirescin scaffold is proposed to switch twice from PKS to 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA)-like biochemistry during biosynthesis. Disruption of the S-adenosylmethionine (SAM)-dependent methyltransferase, TaQ, shifts production toward two novel myxovirescin analogues, designated myxovirescin Q(a) and myxovirescin Q(c). NMR analysis of purified myxovirescin Q(a) revealed the loss of the methoxy carbon atom. This novel analogue lacks bioactivity against E. coli. 相似文献
240.
Preparation, textural and structural characterizations as well as acid properties of some aluminium, zirconium pillared montmorillonite (from Algerian bentonite) and including alumina or zirconium pillared montmorillonite supported palladium are reported. Heat resistant basal spacings of 1.7 nm, surface areas in the range of 250–300 m2/g and micropore volumes of about 0.1 cm3/g were obtained. The acid activation of montmorillonite prior pillaring conduces to a resulting material with significantly higher pore volume and acidity. The improvement in acidity is mainly of the Brønsted acid type. The modification of zirconium-pillared montmorillonite with sulfate ions affects the structural properties of the pillared sample but gives a material with strong acid properties and both Lewis and Brønsted acid types are enhanced. It is reported also that textural and structural properties are not affected by the impregnation of a metallic function (1 wt.% Pd loading) but the acid properties changed. The pillared montmorillonite supported palladium has more Brønsted acidity than does the pillared montmorillonite. Decomposition of isopropanol was studied on these systems at low reaction temperature. 相似文献