排序方式: 共有62条查询结果,搜索用时 234 毫秒
41.
Ghadbane Mouloud Harzallah Daoud Jaouadi Bassem Ibn Laribi Atef Belhadj Hani 《Applied biochemistry and biotechnology》2013,171(8):2186-2200
A bacteriocin-producing strain (9,000 AU/ml) was isolated from the rhizosphere of Algerian healthy plants Ononis angustissima Lam. and identified as Bacillus clausii strain GM17. The bacteriocin, called Bac-GM17, was purified from the culture supernatant after heat treatment, ammonium sulfate precipitation, Sephadex G-50 chromatography and Mono Q fast-performance liquid chromatography (FPLC). Based on matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis, the purified Bac-GM17 is a monomer protein with a molecular mass of 5,158.11 Da. The N-terminal sequencing allowed for the straightforward identification of its first 20 residues, which were of pure bacteriocin. It also revealed that this bacteriocin contained a unique sequence, namely DWTCSKWSCLVCDDCSVELT, which suggests the identification of a novel compound. Bac-GM17 was extremely heat stable (20 min at 120 °C) and was stable within the pH range (3–9). It was found to be resistant to the proteolytic action of trypsin, pepsin, papain, pronase E, and proteinase K. It was also noted to display a bactericidal mode of action against Agrobacterium tumefaciens C58 and a fungistatic mode of action against Candida tropicalis R2 CIP203. 相似文献
42.
Fatima Belhadj Prof. Alain Moissette Dr. Claude Brémard Dr. Matthieu Hureau Prof. Zoubir Derriche 《Chemphyschem》2011,12(7):1378-1388
The locations of Brønsted acid sites (BAS) in the channels of medium‐pore zeolites have a significant effect on the spontaneous ionization of para‐terphenyl (PP3) insofar as spatial constraints determine the stability of transition states and charge‐transfer complexes relevant to charge separation. The ionization rates and ionization yield values demonstrate that a strong synergy exists between the H+ polarization energy and spatial constraints imposed by the channel topology. Spectroscopic and modeling results show that PP3 incorporation, charge separation, charge transfer and charge recombination differ dramatically among zeolites with respect to channel structure (H‐FER, H‐MFI, H‐MOR) and BAS density in the channel. Compartmentalization of ejected electrons away from the initial site of ionization decreases dramatically the propensity for charge recombination. The main mode of PP3.+ decay is hole transfer to form AlO4H.+ ??? PP3 charge‐transfer complexes characterized by intense absorption in the visible range. According to the nonadiabatic electron‐transfer theory, the small reorganization energy in constrained channels explains the slow hole‐transfer rate. 相似文献
43.
Simon CM Belhadj T Chatel B Amand T Renucci P Lemaitre A Krebs O Dalgarno PA Warburton RJ Marie X Urbaszek B 《Physical review letters》2011,106(16):166801
The energy states in semiconductor quantum dots are discrete as in atoms, and quantum states can be coherently controlled with resonant laser pulses. Long coherence times allow the observation of Rabi flopping of a single dipole transition in a solid state device, for which occupancy of the upper state depends sensitively on the dipole moment and the excitation laser power. We report on the robust population inversion in a single quantum dot using an optical technique that exploits rapid adiabatic passage from the ground to an excited state through excitation with laser pulses whose frequency is swept through the resonance. This observation in photoluminescence experiments is made possible by introducing a novel optical detection scheme for the resonant electron hole pair (exciton) generation. 相似文献
44.
In this paper, we theoretically investigate the spatial resolution of a triangular two-dimensional photonic crystal superlens. We prove that this resolution can be improved by optimizing the air hole radius as well as the air hole shape. First, it is found that by decreasing the radius of the air holes, the spatial resolution is improved significantly. Next, we demonstrate that using elliptic air holes instead of circular air holes in a triangular two-dimensional photonic crystal can leads to good-quality images and focusing, with effective refractive index neff=−1 and enhanced image resolution. It is also shown that for the case of two sources, the resolution of such a photonic crystal lens can be made indeed better than the radiation wavelength. 相似文献
45.
D. Castagne L. Belhadj Salem L. Delattre B. Nusgens G. Piel 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):105-107
Natural cyclodextrins (CD) and some of their derivatives have been tested in order to evaluate their cytotoxicity on LT2 endothelial
cells. After 1 h of treatment with concentrations not higher than 10 mM, the number of cells was quantified by measuring DNA
content. No significative decrease in the DNA amount was observed except for the dimethyl-β-CD at the highest tested concentration. 相似文献
46.
Nesrine Hafedh Faouzi Aloui Vincent Dorcet Houcine Barhoumi 《Comptes Rendus Chimie》2018,21(7):652-658
A short and efficient synthetic pathway leading to a new chiral π-conjugated system is reported. The X-ray structure of the target compound was determined and showed a helical conformation. Its resolution was successfully accomplished, leading to two enantiomers in high optical purity, and their chiroptical properties were examined experimentally. The photophysical properties of the organic material were also evaluated, showing an emission in the visible region, and HOMO and LUMO levels have been estimated experimentally, demonstrating an electrochemical band gap of 2.37 eV. 相似文献
47.
Nesrine Belhadj Maxence Lailliau Roland Benoit Philippe Dagaut 《Molecules (Basel, Switzerland)》2021,26(23)
In the present study, we investigated the oxidation of 2500 ppm of di-n-butyl ether under fuel-rich conditions (φ = 2) at low temperatures (460–780 K), a residence time of 1 s, and 10 atm. The experiments were carried out in a fused silica jet-stirred reactor. Oxidation products were identified and quantified in gas samples by gas chromatography and Fourier transform infrared spectrometry. Samples were also trapped through bubbling in cool acetonitrile for high-pressure liquid chromatography (HPLC) analyses. 2,4-dinitro-phenylhydrazine was used to derivatize carbonyl products and distinguish them from other isomers. HPLC coupled to high resolution mass spectrometry (Orbitrap Q-Exactive®) allowed for the detection of oxygenated species never observed before, i.e., low-temperature oxidation products (C8H12O4,6, C8H16O3,5,7, and C8H18O2,5) and species that are more specific products of atmospheric oxidation, i.e., C16H34O4, C11H24O3, C11H22O3, and C10H22O3. Flow injection analyses indicated the presence of high molecular weight oxygenated products (m/z > 550). These results highlight the strong similitude in terms of classes of oxidation products of combustion and atmospheric oxidation, and through autoxidation processes. A kinetic modeling of the present experiments indicated some discrepancies with the present data. 相似文献
48.
X-ray photoelectron and Raman studies of microwave Plasma Assisted Chemical Vapour Deposition (PACVD) diamond films 总被引:1,自引:0,他引:1
X-ray photoelectron and Raman spectroscopies were used to investigate the chemical and the structural properties of thin diamond films synthesised by Plasma Assisted Chemical Vapour Deposition (PACVD). Continuous polycrystalline diamond films were grown under different plasma conditions and based on the combination of detailed XPS and Raman spectroscopic analysis two main topics are highlighted (i) the stress measurements were discussed by distinguishing clearly the chemical effects from the mechanical effects; (ii) an electronic gap at 2.7 eV probed by Raman resonance that corresponds to an energy loss peak on the XPS carbon signal, was related to the surface hydrogenation. 相似文献
49.
Nesrine Louhichi Amel Houas Naoufel Ben Hamadi Moncef Msaddek 《Journal of heterocyclic chemistry》2012,49(2):267-271
In explorations of syntheses and chemistry of spiroheterocycles, we found that the reaction of 2‐diazopropane with (E)‐α‐arylidenepyrrolin‐2‐one, (E)‐α‐arylidene‐γ‐butyrolactone, and (E)‐arylidene‐N‐arylsuccinimide derivatives produced spiro‐Δ1‐pyrazolines. The photolysis of Δ1‐pyrazolines has led to cyclopropanes. The structures of the obtained adducts have been assigned by means of spectroscopic measurements. J. Heterocyclic Chem., (2011). 相似文献
50.