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71.
Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength. 相似文献
72.
Hanen Ben Hassen Imen Ammar Karima Belghith Hamadi Attia 《Journal of the science of food and agriculture》2013,93(1):61-66
BACKGROUND: In Tunisia, prickly pear fruit grow spontaneously; it is consumed as fresh fruit, juice or jam. When the fruit is used for juice production, the seeds are discarded and go to waste. Our study aimed to extract biomolecules from seeds by producing value‐added products from the fruits. RESULTS: An amylase from Opuntia ficus‐indica seeds was extracted and purified to homogeneity. An increase in specific activity of 113‐fold was observed. The apparent molecular mass of the enzyme is 64 kDa. The optimum pH and temperature for enzyme activity were pH 5 and 60 °C, respectively. Under these conditions, the specific activity is 245.5 U mg?1. The enzyme was activated by Co2+ and Mg2+ (relative activity 117% and 113% respectively) at lower ion concentrations. It was strongly inhibited by Mn2+ and Fe2+. Cu2+ inhibited totally the activity of this enzyme, but Ca2+ has an inhibitory effect which increases with ion concentration. CONCLUSION: The extracted enzyme belongs to the exo type of amylases and is classified as a β‐cyclodextrin glycosyltransferase since it generates mainly β‐cyclodextrin from starch. It exhibits high thermal stability and a broad range of pH stability, making it a promising prospect for industrial and food applications. Copyright © 2012 Society of Chemical Industry 相似文献
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通过凝胶注模工艺,采用非水基凝胶体系,成功地制备了铝铜合金多孔材料.通过预备试验优化工艺,采用球磨的混粉手段,球料比为1:4,球磨时间30 min,非永基凝胶体系采用1 ml单体(HEMA),8 ml溶剂(PBO),0.2 ml交联剂(DEGDA),0.02 ml催化剂-引发剂(DMA-CHP),1.2g分散剂(PVP).研究不同烧结工艺参数对材料性能的影响.结果表明,在不添加发泡剂的前提下,烧结温度660℃时,烧结体的孔隙率为42.8%.烧结体中形成的第二相CuAl2,经过热处理后可使显微硬度明显提高,最大硬度可以达到95 HV. 相似文献
75.
Touia Amina Benyahia Karima Tekin Adem 《Journal of Superconductivity and Novel Magnetism》2021,34(10):2689-2698
Journal of Superconductivity and Novel Magnetism - The structural, electronic, optical, and thermo-electric properties of LuNiBi and LuNiSb Half-Heusler have been studied using a full potential... 相似文献
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通过凝胶注模工艺,采用非水基凝胶体系,成功地制备铝铜坯体.通过扫描电镜观察脱脂前聚合物完全包裹粉末颗粒,脱脂后金属坯体中聚合物完全脱除.通过反应机理得出聚合物三维网络结构的化学式.采用热分析手段、热重和红外连用系统分析金属坯体的脱脂过程,根据Coats-Redfern方法对非等温热失重率曲线的数据进行动力学研究,建立动力学方程.在不同的升温速率下聚合物脱脂反应级数为1,活化能在79.86-108.63 k J·mol-1范围内,指前因子反应指数在106-107min-1,活化能的结果表明反应对温度和动力学比较敏感.脱脂主要分为两个阶段,在240-350℃主要是聚合物链段的分解,在350-470℃主要是聚合物网状结构的解聚和解交联反应,同时脱脂阶段主要产生CO2、CO、NO2和H2O挥发性气体. 相似文献
77.
Medhat Karima 《Journal of Materials Shaping Technology》1989,7(4):213-227
Sheet metal engineering is a complex, iterative and interactive process. The whole function of stamping engineering is to select the material, devise the process, the tooling, the set-up and the operational support infrastructure to produce the final part shape, subject to part specifications, budget, and time constraints. There is little application of formal engineering science. It follows from this practice that there is a requirement for extensive die tryout and rework and there is usually little confidence that the sheet steel, the process, and tooling have been optimized. This leads to high cost, long leadtimes, schedule delays and, most important, a lack of control of the whole stamping cycle. The paper provides an overview of stamping engineering from the micro and the macro perspectives. The different engineering tasks are reviewed from a system’s perspective. The role of computer modelling is also examined, with emphasis on the applicability of the different computer tools and need for a broad methodology to support the application of the computer tools. The paper concludes by describing some of the efforts at FTI aimed at formalizing and documenting some of the stamping engineering tasks’ expertise. This work reinforces the need and the necessity for a strong relationship and interaction between the steel supplier, the lubricant supplier, the press supplier, the tooling supplier, and the stamping operation team. 相似文献
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Mounir El Achaby Youness Essamlali Nassima El Miri Asmae Snik Karima Abdelouahdi Aziz Fihri Mohamed Zahouily Abderrahim Solhy 《应用聚合物科学杂志》2014,131(22)
Bio‐nanocomposite films based on chitosan/polyvinylpyrrolidone (CS/PVP) and graphene oxide (GO) were processed using the casting/evaporation technique. It has been found that the three components of bio‐nanocomposites can be easily mixed in controlled conditions enabling the formation of thick films with high quality, smooth surface and good flexibility. Structural and morphological characterizations showed that the GO sheets are well dispersed in the CS/PVP blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and GO sheets thus improving their properties. It has been found that the water resistance of the CS/PVP blend is improved, and the hydrolytic degradation is limited by addition of 0.75 and 2 wt % GO. The modulus, strength, elongation and toughness of the bio‐nanocomposites are together increased. Herein, the steps to form new bio‐nanocomposite films have been described, taking the advantage of the combination of CS, PVP and GO to design the aforementioned bio‐nanocomposite films, which allow to have extraordinary properties that would have promising applications as eventual packaging materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41042. 相似文献
79.
Karima Adel-Aissanou Djamil Aïssani Nathalia Djellab Noufissa Mikou 《Telecommunication Systems》2014,57(2):197-207
In this paper, we exploit the utility of Hello messages in the Ad hoc networks to study the impact of their transmission frequencies on the connectivity of the network. Assuming that the Hello messages arrive at a given node according to a Poisson process, we model a cluster-head motion (respectively an ordinary node motion) using a random process. This model allows us to find the critical value of the transmission frequency of Hello messages. We also have investigate a fundamental property of an Ad hoc network: its connectivity. We then analyze the number of neighbors of a given node, the isolation probability, the handoff probability and the probability that the considered network is connected, i.e. each node can communicate with an other node via the network. 相似文献
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Karima Habbout Junichi Omura Charifa Awada Alice Bourgeois Yann Grobs Vinod Krishna Sandra Breuils-Bonnet Eve Tremblay Ghada Mkannez Sandra Martineau Valrie Nadeau Florence Roux-Dalvai Mark Orcholski Jey Jeyaseelan David Gutstein Franois Potus Steeve Provencher Sbastien Bonnet Roxane Paulin Olivier Boucherat 《International journal of molecular sciences》2021,22(6)