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排序方式: 共有1475条查询结果,搜索用时 78 毫秒
71.
Nor Hafizah A. K. Viswanathan K. K. Aziz Z. A. Lee J. H. 《Journal of Mechanical Science and Technology》2018,32(5):2155-2162
Journal of Mechanical Science and Technology - Based on first order shear deformation theory, free vibrational behaviour of antisymmetric angle-ply composite annular plate is investigated. The... 相似文献
72.
Renewable chemicals are of growing importance in terms of opportunities for environmental concerns over fossil‐based chemicals. Lignocellulosic biomass can be converted into energy and chemicals via thermal and biological processes. Among all the transformation processes available, fast pyrolysis is the only one to produce a high yield of a liquid‐phase product called bio‐oil or pyrolysis oil. Bio‐oil is considered to be a promising substitute for phenol in phenol formaldehyde (PF) resin synthesis. In this work, bio‐based phenolic resins have been formulated, partially substituting phenol by bio‐oils from two Canadian whole‐tree species. The new resins are produced by replacing 25, 50, and 75% of phenol with bio‐oil for each species (three bioresins per species). The aim of this study is to synthesize renewable resins with competitive price and satisfactory quality. The results obtained have shown that substitution degree up to 50% provided reactivity and performance equal or superior to the pure PF resin. They also present a good storage stability, improved shear strength, and thermal stability comparable to the pure PF. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40014. 相似文献
73.
M. M. El-Halwagi M. A. El Hefny H. A. Talaat Aziz M. H. Sorour A. G. Abulnour N. M. H. El-Defrawy 《Starch - St?rke》1992,44(1):2-7
The present paper outlines the approach and principal results of a full-fledged performance evaluation and functional analysis program conducted at the Egyptian Starch and Glucose Company that has been wholly documented elsewhere [12]. The ultimate goal of the program is to come up with well-defined and appropriate courses of action to improve products quality, plant productivity and overall economy. The paper also reports the results of additional computer work that has been undertaken to enhance the applicability of the results. The adopted methodology for applying the developed computer material balance (MASSBAL) in the evaluation program and in analysing the impacts of stepwise improvements in the individual plant sectors of concern is also presented. 相似文献
74.
Aziz Boutouil Ilhame Elazhary Hicham Ben El Ayouchia Hafid Anane Mohammadine El Haddad 《Journal of Adhesion Science and Technology》2020,34(5):549-578
Abstract4-[4-(1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (ITBP) and 4[4-(1H-1,2,4-triazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (TTBP) are synthesized as new heterocyclic compounds of the triazole derivative family and tested successfully as potential inhibitors for MS in 1?M H2SO4 corrosive medium by using gravimetric analysis, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive X-ray spectroscopy (EDX). Polarization curves show that the tested inhibitors are mixed-type inhibitors. Scanning electron microscopy (SEM) affirmed the existence of an adsorbed film on the steel surface. Monte Carlo simulations were in excellent agreement with the experimental tests. Abbreviation: PDP: Potentiodynamic Polarization; EIS: Electrochemical impedance spectroscopy; DFT: Density functional theory; MC: Monte Carlo 相似文献
75.
Mohamed Nadjib Boukhatem Abdelkrim Kameli Mohamed Amine Ferhat Fairouz Saidi Khadidja Tayebi 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2014,9(1):13-21
Several essential oils of medicinal plants possess proven antimicrobial activity and are suitable for applications on the food industry. The oil from Cymbopogon citratus (lemongrass) has been reported to have a wide range of biological activities. However, there are few controlled studies confirming its antimicrobial activity. The aim of our study was to assess the antimicrobial potential of lemongrass oil against a wide spectrum of food spoilage and pathogenic bacteria and yeast in liquid and vapour phase. The chemical composition of the oil was analyzed by gas chromatography; 14 components were identified and geranial (28.93 %), neral (24.30 %) and myrcene (23.92 %) were the most abundant constituents. Lemongrass oil showed potent antimicrobial activity against Gram positive bacteria and exhibited the strongest antifungal effect against Candida albicans and C. parapsilosis. Minimum inhibitory concentration varied from 0.019 to 1.25 mg mL?1 for Gram positive bacteria and yeasts, indicating Staphylococcus aureus, S. epidermidis and C. albicans as the most susceptible strains. Moreover, the diameter of inhibition zone (DIZ) increased with increasing essential oil (EO) volume. Considerably superior antimicrobial activity was observed in the vapour phase. The DIZ resulting from the exposure to EO vapour was significantly larger than that from the same volume in the liquid phase. The DIZ varied from 22 to 90 mm for Candida strains. There is growing evidence that EO in vapour phase are effective antimicrobial systems and that they do have advantages over the use of oil in liquid phase. Our results imply that lemongrass oil could be useful for the development of novel types of natural preservatives for food control. 相似文献
76.
Differentiation of Mechanically and Chemically Extracted Hazelnut Oils Based on their Sterol and Wax Profiles
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Cansu Ekin Gumus Asli Yorulmaz Aziz Tekin 《Journal of the American Oil Chemists' Society》2016,93(12):1625-1635
The sterol and wax content of solvent extracted (SEHO) and cold pressed hazelnut oils (CPHO) were compared. A total of 48 samples from 19 hazelnut varieties were collected for two successive crop years from four different geographical districts in Turkey. Hazelnuts were processed to oil with a laboratory scale press, than the remaining oil in cake was extracted with n‐hexane. CPHO and SEHO were evaluated for their wax, sterol and squalene contents. Results showed that sterol, squalene and wax contents of all individual cultivars were higher in SEHO than those of CPHO, indicating the higher solubility of these compounds in solvent. Total sterol contents ranged between 1088.56 (Kargalak)—1609.39 mg/kg (Mincane) for CPHO and 1590.86 (Çak?ldak)—2897.26 mg/kg (Mincane) for SEHO. Hazelnut oils were found to be richer of C36‐38 esters than C40‐46 group. Total wax content was between 24.19 (Kargalak)—94.58 mg/kg (Ku?) for CPHO and 81.46 (Kargalak)—160.92 mg/kg (Akçakoca) for SEHO. The squalene amounts of the samples obtained by hexane extraction were between 499.75 (Allahverdi)—885.36 mg/kg (Cavcava), while it varied between 288.55 (Kargalak)—647.68 mg/kg (Mincane) in cold pressed oils. Significant and obvious variations between SEHO and CPHO were verified by principal component and hierarchical cluster analysis. Geographical discrimination was also achieved by discriminant analysis. 相似文献
77.
Qingguo Tian Robeena M. Aziz Gary D. Stoner Teven J. Schwartz 《Journal of food science》2005,70(1):C43-C47
ABSTRACT: The capabilities of mass spectrometry for microscale determination of anthocyanins were investigated using high-performance liquid chromatography electrospray ionization mass spectrometry (LC-ESI/ MS) and tandem mass spectrometry (MS-MS). Four anthocyanins [cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3–(2G −xylosylrutinoside) and cyanidin 3-rutinoside] were characterized in black raspberry samples by LC-ESI/MS-MS using both positive and negative ion analyses. Quantification of anthocyanins was conducted using ESI/MS-MS with selected reaction monitoring (SRM). Linear responses of several anthocyanins were determined during MS-MS analyses. Detection limits as low as 1 femtomol for most anthocyanins were obtained during ESI/MS-MS. Compared with other quantitative procedures such as high-performance liquid chromatography (HPLC) and ultraviolet/visible spectrophotometry, the current method provides an improved sensitive, specific technique for direct determination of intact anthocyanins. The developed methodology was successfully applied to analysis of trace levels of anthocyanins in human plasma and epithelial cells. 相似文献
78.
A (Ni1/3Co1/3Mn1/3)CO3 precursor with an uniform, spherical morphology was prepared by coprecipitation using a continuously stirred tank reactor method. The as-prepared spherical (Ni1/3Co1/3Mn1/3)CO3 precursor served to produce dense, spherical Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 (0 ≤ x ≤ 0.15) cathode materials. These Li-rich cathodes were also prepared by a second synthesis route that involved the use of an M3O4 (M = Ni1/3Co1/3Mn1/3) spinel compound, itself obtained from the carbonate (Ni1/3Co1/3Mn1/3)CO3 precursor. In both cases, the final Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 products were highly uniform, having a narrow particle size distribution (10-μm average particle size) as a result of the homogeneity and spherical morphology of the starting mixed-metal carbonate precursor. The rate capability of the Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 electrode materials, which was significantly improved with increased lithium content, was found to be better in the case of the denser materials made from the spinel precursor compound. This result suggests that spherical morphology, high density, and increased lithium content were key factors in enabling the high rate capabilities, and hence the power performances, of the Li-rich Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 cathodes. 相似文献
79.
Merzouk SA Saker M Reguig KB Soulimane N Merzouk H Guermouche B Berrouiguet AY Hichami A Narce M Khan NA 《Lipids》2008,43(6):485-497
In this work, we assessed the in-vitro effects of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) (final concentration, 15 microM) on T cell blastogenesis, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status in type I diabetic patients with or without complications. Con A stimulated lymphocyte proliferation, glucose uptake, intracellular reduced glutathione levels and catalase activity were lower in diabetics as compared to controls, regardless to the presence of complications. EPA and DHA diminished T-lymphocyte proliferation and IL-2 production but enhanced IL-4 secretion in both diabetic and control groups. No changes in the levels of reduced glutathione and in the activities of catalase and SOD were observed in control T cells cultured in the presence of EPA and DHA. However, in diabetic patients, addition of n-3 PUFA to culture induced an increase in T cell levels of reduced glutathione and hydroperoxide, and in activities of catalase and SOD. Low levels of arachidonic acid (C20:4n-6) were found in plasma membrane phospholipids of lymphocytes from diabetic patients compared to controls. Incubation of lymphocytes with EPA and DHA was associated with an incorporation of these fatty acids in membrane phospholipids. In conclusion, the beneficial effects of n-3 PUFA on T cell functions in type I diabetes could be attributed to their suppressive action and modulation of cytokine secretion, and to the improvement of intracellular oxidative status. 相似文献
80.
Asmaa Argoub Rachid Ghezini Cherifa Bachir Bouhadjar Boukoussa Amine Khelifa Abdelkader Bengueddach Peter G. Weidler Rachida Hamacha 《Journal of Porous Materials》2018,25(1):199-205
MIL-101@g-C3N4 nanocomposite was prepared by solvothermal synthesis and used for CO2 adsorption. The parent materials (MIL-101 and g-C3N4) and the MIL-101@g-C3N4 were characterized by X-ray diffraction, argon adsorption/desorption, Fourier transform infrared spectroscopy, thermal analysis (TG/DTA), transmission electronic microscopy, and Energy-dispersive X-ray spectroscopy. The results confirmed the formation of well-defined MIL-101@g-C3N4 with interesting surface area and pore volume. Furthermore, both MIL-101 and MIL-101@g-C3N4 were accomplished in carbon dioxide capture at different temperatures (280, 288, 273 and 298 K) at lower pressure. The adsorption isotherms show that the nanocomposite has a good CO2 adsorption affinity compared to MIL-101. The best adsorption capacity is about 1.6 mmol g?1 obtained for the nanocomposite material which is two times higher than that of MIL-101, indicating strong interactions between CO2 and MIL-101@g-C3N4. This difference in efficacy is mainly due to the presence of the amine groups dispersed in the nanocomposite. Finally, we have developed a simple route for the preparation of an effective and new adsorbent for the removal of CO2, which can be used as an excellent candidate for gas storage, catalysis, and adsorption. 相似文献