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Moufida Romdhani-Younes Ines Gara Amine Mezni Mohamed Moncef Chaabouni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1074-1081
Abstract The β,β′-dihydroxydithioethers, derived from oxirane, have been converted into dithioethers dithiols in good yields. A colloidal solution of gold nanoparticles (AuNPs) with 5,8-dithiadodecane-3,10-dithiol was prepared and showed a good stability from tight binding offered by the thiol group on the Au surfaces. 相似文献
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Apart from long-known and applied nanostructures like carbon black for tyres or pigments for coatings nanotechnology has created highly sophisticated structures used for nano/molecular electronics,diagnostics,drug delivery, UV-absorbers etc.Often the main question to be solved analytically is the local determination of tiny amounts of chemicals resulting in an ever increasing need for highly sensitive as well as locally resolved techniques.Applications of techniques like mass spectroscopy,transmission el... 相似文献
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Dorra Driss Anissa Haddar Raoudha Ghorbel Semia Ellouz Chaabouni 《Applied biochemistry and biotechnology》2014,173(6):1405-1418
Penicillium occitanis xylanase 2 expressed with a His-tag in Pichia pastoris, termed PoXyn2, was immobilized on nickel-chelate Eupergit C by covalent coupling reaction with a high immobilization yield up to 93.49 %. Characterization of the immobilized PoXyn2 was further evaluated. The optimum pH was not affected by immobilization, but the immobilized PoXyn2 exhibited more acidic and large optimum pH range (pH 2.0–4.0) than that of the free PoXyn2 (pH 3.0). The free PoXyn2 had an optimum temperature of 50 °C, whereas that of the immobilized enzyme was shifted to 65 °C. Immobilization increased both pH stability and thermostability when compared with the free enzyme. Time courses of the xylooligosaccharides (XOS) produced from corncob xylan indicated that the immobilized enzyme tends to use shorter xylan chains and to produce more xylobiose and xylotriose initially. At the end of 24-h reaction, XOS mixture contained a total of 21.3 and 34.2 % (w/w) of xylobiose and xylotriose with immobilized xylanase and free xylanase, respectively. The resulting XOS could be used as a special nutrient for lactic bacteria. 相似文献
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Chakib Hrizi Ameni Trigui Nassira Chniba-Boudjada Slaheddine Chaabouni 《Journal of solid state chemistry》2011,184(12):3336-3344
α-[C6H4(NH3)2]2Bi2I10, which is a new material containing low-dimensional iodobismuthate anions, was synthesized and through its single crystal X-ray diffraction measurements, was proven to crystallize at room temperature in the centrosymmetric space group P21/c. It consists of a p-phenylenediammonium dication and a discrete (0-D) anion built up of edge-sharing bioctahedron. Due to the hydrogen bonds and the interatomic distances (Bi-I, I?I and π-π) changes, α-phase was transformed into the corresponding centrosymmetric β-phase, β-[C6H4(NH3)2]2Bi2I10, through a single-crystal to single-crystal transformation occurring upon cooling to −28/−26 °C. Below the transition temperature, β-[C6H4(NH3)2]2Bi2I10 crystallizes in the monoclinic system, centrosymmetric space group P21/n. Besides, the optical transmission measurements on α-[C6H4(NH3)2]2Bi2I10 thin films have revealed two absorption bands at 2.47 and 3.01 eV. Finally, two room temperature photoluminescence emissions attributed to excitons radiative recombinations confined within the bioctahedra Bi2I104−, were observed in the red spectral range at 1.9 and 2.05 eV energy. 相似文献
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Four new fulgimides possessing a fluorescent coumarin unit were synthesized from the corresponding fulgides, and their photochromic as well as fluorescence properties were investigated. The open-ring forms of coumarin fulgimides were found to exhibit fluorescence in the visible region. Upon exposure to UV light, the fulgimides were transformed into the nonfluorescent closed-ring forms, which can be reverted to the initial fluorescent open-ring forms on exposure to visible light. The efficiency of quenching of fluorescence was as high as 95% at the photostationary state of UV irradiation. 相似文献
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New Thermostable Amylase from <Emphasis Type="Italic">Bacillus cohnii</Emphasis> US147 with a Broad pH Applicability 总被引:1,自引:0,他引:1
Ghorbel RE Maktouf S Massoud EB Bejar S Chaabouni SE 《Applied biochemistry and biotechnology》2009,157(1):50-60
A new thermophilic bacterial strain identified as Bacillus cohnii US147 was isolated from the southern Tunisian soil. The identification was based on physiological tests and molecular techniques
related to the 16S ribosomal ribonucleic acid. The isolated strain produced amylase, which was purified. This amylase had
an apparent molecular mass of 30 kDa as estimated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Amylase
US147 showed K
m and V
max values of 0.7 mg/ml and 2.2 U/ml, respectively, with starch as the substrate. The enzyme was active in acid and basic pH
and had a maximal activity on starch at pH 9 and 70 °C. The enzyme was stable at pH 9 for 72 h and retained half of its activity
after incubation at 70 °C for 150 min. A partially inhibition (15%, 25%, 23%, 20%, and 22%) was obtained with 1 mM SDS, 1 mM
NaBO3, 1 mM H2O2, 1 mM Zn+2, and 5 mM ethylenediamine tetraacetic acid (EDTA), respectively. The amylase recovered its original activity by the addition
of 10 mM Ca 2+ to the 5 mM EDTA. These properties indicated a possible use of this amylase in starch saccharification, in detergent, and
in other industrial applications. 相似文献
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用具有大能隙的本征半导体(SrTiO3及SnO2)粉末作本体,分别掺杂1%(原子百分数)的Eu2O3;所得物质表现出Eu3+离子的线发射光谱特性,但相对发光强度及光谱形状有相当大的变化。X射线衍射结构分析显示Eu3+在SrTiO3晶格里是处在间隙位置,而它在SnO2晶格里则形成新物相Eu2Sn2O7。 相似文献
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