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41.
Potato cell wall was used as low-value source for the enzymatic extraction of galactan-rich rhamnogalacturonan I (RG I). The effects of selected reaction parameters of endo-polygalacturonase from Aspergillus niger-catalyzed isolation of RG I and their interactions were investigated by response surface methodology. Models were developed to relate independent parameters (cell wall concentration, enzyme amount, reaction time) to responses (yield, neutral sugar content, saccharide molar composition, weak acidic fraction proportion). The most significant parameters that affected extracted polysaccharide yield and its galactose (Gal) and arabinose (Ara) contents were the cell wall concentration and enzyme amount. The interaction between the cell wall concentration and the reaction time was the most determinant for the yield. However, the cell wall concentration and the enzyme amount exhibited significant interaction effect on Gal and Ara contents. Comparison of predicted and experimental values validated the established predicted models, which can be used to identify the conditions for the isolation of RG I-type pectic polysaccharides with selected structural and saccharide composition properties. The monosaccharide composition and the linkage patterns confirmed the isolation of galactan-rich RG I type pectic polysaccharides. The present study is expected to increase the capability to generate RG I targeting specific composition and functional properties. 相似文献
42.
Rousseau Vincent; Salek Salwa; Aubé Caroline; Morin Estelle M. 《Canadian Metallurgical Quarterly》2009,14(3):305
Recent research has demonstrated that the perception of injustice at work may increase psychological health-related problems. The purpose of this study is to examine the moderating effect of coworker support and work autonomy on the relationships between both distributive and procedural justice and psychological distress. Results, on the basis of responses to questionnaires given to 248 prison employees, show that coworker support moderates the relationships between both forms of justice and psychological distress. Specifically, these relationships are weakened when employees benefit from a high level of coworker support. Furthermore, work autonomy moderates the relationship between procedural justice and psychological distress but not the relationship between distributive justice and psychological distress. Thus, procedural injustice is less likely to increase psychological distress when the level of work autonomy is high. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
Jean Mamelona Émilien Pelletier Karl Girard-Lalancette Jean Legault Salwa Karboune Selim Kermasha 《Food chemistry》2007,104(3):1040-1047
The antioxidant activity (oxygen radical absorbance capacity, ORAC) and total phenols and flavonoids were determined in extracts from digestive tract, gonads, muscles and respiratory apparatus of sea cucumber, Cucumaria frondosa. Total phenols content varied from 22.5 to 236.0 mg of gallic acid equivalents/100 g dw, and flavonoids from 2.9 to 59.8 mg of rutin equivalents/100 g. ORAC values ranged from 140 to 800 μmol of Trolox equivalents/g dw. Among all extracts, best antioxidant potencies were observed in ethyl acetate extracts from digestive tract, and in acetonitrile-rich fractions obtained from mixed extracts using acetonitrile/TFA (trifluoroacetic acid) acidified water on muscles, gonads and respiratory apparatus. The weakest potencies were observed with water extracts from digestive tract and respiratory apparatus, and with water-rich fractions obtained from mixed extraction of gonads and muscles. A significant correlation was observed between ORAC values and total phenol content in extracts and fractions of gonads and muscles, but ORAC and phenols were not correlated in digestive tract and respiratory apparatus extracts. ORAC values were significantly correlated (p < 0.05) with total flavonoids in all extracts. Successive eluates obtained from solid-phase extraction of water-rich fractions using C18 cartridge showed ORAC values (105–500 μmol of TE/g) reaching up to 2.3 times the potency of their parent fractions. Flavonoids are suggested to be mainly responsible for observed activities. Our results provide a first quantitative evaluation of C. frondosa tissues as useful sources of antioxidants for human consumption. 相似文献
44.
Ahmed Wagdi A. El-Shennawi Mohamed A. Mandour Morsi M. Morsi Salwa A. M. Abdel-Hameed 《Journal of the American Ceramic Society》1999,82(5):1181-1186
Uniform, ultrafine, microcrystalline, hard, pyroxenic glass-ceramic materials have been obtained successfully from basalt rock; instead of adding nucleation catalysts, the FeO:Fe2 O3 , CaO:Na2 O, and CaO:MgO ratios have been rectified. This process has been accomplished by deliberately adding the smallest permissible amounts of oxidizers, limestone, dolomite, and soda ash (as additives) that are necessary to fulfill the monominerality requirements; these requirements affect the melting, workability, crystallization, and microstructure of the glass-ceramics. The melting temperature decreases as the ratios decrease (beyond certain limits); in addition, the workability, crystallization, and microstructure also improve as the ratios decrease. An almost-stable solid solution of augite or aegirine-augite composition is the only crystalline phase that is formed. The minimal FeO:Fe2 O3 ratio and the likelihood of a greater affinity of the Na+ cation for the Fe3+ cation, rather than the Al3+ cation, may be responsible for increasing the stability and widening of the crystallization field of the complex aluminum-bearing pyroxene solid solution. 相似文献
45.
Salwa.M. El-Mesallamy 《Egyptian Journal of Petroleum》2019,28(3):253-260
A series of polybenzoxazine-clay nanocomposites with various organoclay contents (3, 5, 10, and 20 wt%) were prepared by the one-shot procedure. from organo-montmorillonite (OMMT) and bifunctional benzoxazine, namely, bis-(3-dodecyel-3,4-dihydro-2H-1,3-benzoxazine) isopropane (B-dod). OMMTs were prepared by modification of Na-MMT with different ammonium salts of amines such as tyramine (Tyr), amino lauric acid (ALA) and N,N-dimethyl stearyl amine (DMS). Transmission electron microscope (TEM), X-ray diffraction (XRD) and infrared measurements (FTIR) were used to examine the structure and modification of OMMTs. The morphology of polybenzoxazine nanocomposites (B-dod/Tyr-MMT, B-dod/ALA-MMT, B-dod/DMS-MMT) was investigated by X-ray and TEM analyses. The X-ray analysis and TEM photos indicated that organoclay was exfoliated into polybenzoxazine matrix even at the highest organoclay loading (20%). Mechanical properties (viz, adhesion on metallic substrate, scratch hardness, tensile modulus, and elongation at break) of the prepared nanocomposites were measured. The tensile properties of prepared samples were examined; as the content of modified clay was increased, the tensile modulus increased; however, the elongation at break decreased. In addition, the optimum adhesion and scratch hardness values of the prepared nanocomposites were increased more than the neat resin, also, thermogravimetric analysis has the same manner. Therefore, the prepared nanocomposite materials could be successfully used for metal coatings. 相似文献
46.
Sayed Wafaa S. Tolba Mohammed F. Radwan Ahmed G. Abd-El-Hafiz Salwa K. 《Multimedia Tools and Applications》2019,78(12):16097-16127
Multimedia Tools and Applications - This paper proposes a generalized modified chaotic transition map with three independent parameters. A hardware speech encryption scheme utilizing this map along... 相似文献
47.
Hisham A. Essawy Magda E. Tawfik Ahmed M. Khalil Salwa H. El‐Sabbagh 《Polymer Engineering and Science》2014,54(4):942-948
Different montmorillonites either, completely hydrophilic (Mont‐0), amphiphilic (Mont‐25, Mont‐50, and Mont‐75) or completely hydrophobic (Mont‐100) were used as reinforcing fillers for styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) individually to predict the influence of the different forms on the properties of the rubbers (rheometric characteristics and mechanical properties). The shifts in the glass transition temperatures after the clay insertion were determined from dynamic mechanical thermal analysis to investigate the preference and action of each form. In addition, the storage moduli were used as indications to the corresponding mechanical properties of the samples. The influences could be followed after comparing the impacts of aging conditions on the properties of rubber compositions. The obtained data may provide a platform to suggest the mechanism by which these forms can in some cases act as compatibilizers in addition to their reinforcing/plasticizing effect when employed with the physically incompatible NBR/SBR (50/50) blend, which helps to optimize the properties of nanocomposites based on these blends. The proposed mechanism of action showed good correlation with the results of the mechanical properties and x‐ray diffraction investigations as well. POLYM. ENG. SCI., 54:942–948, 2014. © 2013 Society of Plastics Engineers 相似文献
48.
Zolmitriptan is a potent molecule for treatment of migraine. Its current oral therapies present drawbacks such as slow onset of action, low bioavailability and large inter-subject variability. Fast disintegrating sublingual zolmitriptan tablet (FDST) using freeze-drying technique has been developed to enhance tablet disintegration and dissolution with the intention of speeding drug absorption and onset of effect, hence mitigating the effects on the gastrointestinal dysmotility that typically accompanies the migraine attack. The FDSTs were prepared using different concentrations of gelatin as binder and mannitol or L-alanine as matrix supporting/disintegration enhancing agents. The effect of formulation variables on the physicochemical and solid-state properties, as well as the dissolution behaviour of the tablets, was studied. The formulated FDSTs disintegrated within 30 s and showed significantly faster dissolution rate of zolmitriptan compared to the zolmitriptan oral tablet. Tablet containing 2% gelatin and mannitol showed acceptable weight variation, drug content and friability values. Furthermore, it had a low in-vitro and in-vivo disintegration time (11 s) and it reached 100% of drug release within 30 s. This sublingual formulation gave faster and higher zolmitriptan plasma concentration in rabbits compared to the oral zolmetriptan market product. Zolmitriptan FDST may therefore constitute an advance in the management of acute migraine attacks. 相似文献
49.
50.
Ahmed K. Aboul-Gheit Ateyya A. Aboul-Enein Salwa A. Ghoneim Samia A. Hanafi Ahmed E. Awadallah 《Egyptian Journal of Petroleum》2012,21(2):119-124
H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm) and the smallest pores (0.4–1.7 nm). The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give Ea and ΔS1 values compatible with the characterization data of the catalysts. 相似文献