排序方式: 共有26条查询结果,搜索用时 31 毫秒
1.
Chafa A Tatischeff V Aguer P Barhoumi S Coc A Garrido F Hernanz M José J Kiener J Lefebvre-Schuhl A Ouichaoui S de Séréville N Thibaud JP 《Physical review letters》2005,95(3):031101
We report on the observation of a previously unknown resonance at E(lab)(R)=194.1+/-0.6 keV in the 17O(p,alpha)14N reaction, with a measured resonance strength omegagamma(palpha)=1.6 +/- 0.2 meV. We studied in the same experiment the 17O(p,gamma)18F reaction by an activation method and the resonance-strength ratio was found to be omegagamma(palpha)/omegagamma(pgamma) = 470 +/- 50. The corresponding excitation energy in the 18F compound nucleus was determined to be 5789.8 +/- 0.3 keV by gamma-ray measurements using the 14N(alpha, gamma)18F reaction. These new resonance properties have important consequences for 17O nucleosynthesis and gamma-ray astronomy of classical novae. 相似文献
2.
T. Barhoumi J. L. Monge H. Bouchriha 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,77(3):453-458
We have adapted the model of two consecutive pairs to the study of the
triplet-doublet (T-D) interaction in molecular crystals. We have applied
this model to the modulation of the photoconductivity in crystalline
anthracene by a static magnetic field (MFE) and a microwave field (PDMR). We
were able to reproduce, for the first time, quite perfectly two types of
experiments with the same set of kinetic constants. 相似文献
3.
Al-Jaber HI Al-Qudah MA Barhoumi LM Abaza IF Afifi FU 《Natural product research》2012,26(13):1179-1187
The composition of the essential oil of fresh and air-dried Salvia palaestina Benth. (Lamiaceae) growing wild in Jordan has been studied using gas chromatography-mass spectrometry analysis. The essential oils of fresh and air-dried S. palaestina were mainly composed of sesquiterpene hydrocarbons (52.66% and 65.98%, respectively). The major component detected in the oils of fresh and dry S. palaestina was germacrene D (21.18% and 26.02%, respectively). Air drying resulted in a general increase of sesquiterpene hydrocarbons and a great decrease in the percentage of monoterpene hydrocarbons. 相似文献
4.
5.
6.
We report a method for obtaining highly reproducible surface-enhanced Raman spectroscopy (SERS) of single and double-stranded thiolated DNA oligomers. Following a protocol that relaxes the DNA into an extended conformation, SERS spectra of DNA oligonucleotides are found to be extremely similar, strongly dominated by the Stokes modes of adenine. A spectral correlation function analysis useful for assessing reproducibility and for quantifying the highly complex changes corresponding to modifications in molecular conformation of the adsorbate molecules is introduced. This approach is used to monitor the interaction of DNA with cisplatin, a chemotherapy agent in widespread use. 相似文献
7.
Observations of two spectrally distinct ring breathing modes of guanine and adenine in the surface-enhanced Raman spectrum (SERS) of a dsDNA self-assembled monolayer on an Au nanoshell SERS substrate provide information concerning the orientation of its constituent molecules. The two modes vary with DNA concentration in a highly systematic manner, consistent with studies suggesting DNA molecules tend toward a more horizontal orientation at low-surface concentrations and a more vertical conformation at high concentrations. The introduction of small molecular spacers coadsorbed onto the Au nanoshell surface to "raise" the DNA molecules yields a SERS spectrum consistent with a more upright molecular orientation. 相似文献
8.
Jose J Loudet A Ueno Y Wu L Chen HY Son DH Barhoumi R Burghardt R Burgess K 《Organic & biomolecular chemistry》2011,9(10):3871-3877
Lipophilic energy transfer cassettes like 1 and 2 are more conveniently synthesized than the corresponding hydrophilic compounds, but they are not easily used in aqueous media. To overcome the latter issue, cassettes 1 and 2 were separately encapsulated in silica nanoparticles (ca. 22 nm) which freely disperse in aqueous media. Photophysical properties of the encapsulated dyes 1-SiO(2) and 2-SiO(2) were recorded. The nanoparticles 1-SiO(2) permeated into Clone 9 rat liver cells and targeted only the ER. A high degree of energy transfer was observed in this organelle such that most of the light fluoresced from the acceptor part, i.e. the particles appeared red. Silica nanoparticles 2-SiO(2) also permeated into Clone 9 rat liver cells and they targeted mitochondria but were also observed in endocytic vesicles (lysosomes or endosomes). In these organelles they fluoresced red and red/green respectively. Thus the cargo inside the nanoparticles influences where they localize in cells, and the environment of the nanoparticles in the cells changes the fluorescent properties of the encapsulated dyes. Neither of these findings were anticipated given that silica nanoparticles of this type are generally considered to be non-porous. 相似文献
9.
The knowledge and prediction of physicochemical properties of binary liquid mixtures is of great importance for understanding
intermolecular interactions. Viscosities (η) have been investigated by using density (ρ) and kinematic viscosity (ν) measurements for 1,4-dioxane + water (D–W) mixtures over the entire range of mole fractions under atmospheric pressure,
at 311.15, 316.15 and 320.15 K, in order to increase the studied temperatures range available from the literature and to improve
the investigations. The viscosity Arrhenius activation energy of 1,4-dioxane + water mixtures was calculated from the present
experimental viscosity measurements, and those presented in a previous work at only four temperatures, and for three temperatures
in the present work, over the entire range of composition in the temperatures range from 293.15 to 323.15 K. Based on the
partial molar activation energy from the Arrhenius equation for viscosity, interactions between water and 1,4-dioxane molecules
are discussed. Comparison between some reduced Redlich–Kister functions covering the composition domain shows the existence
of two distinct behaviors. 相似文献
10.
This work was designed to develop an electrochemical sensor based on molecular imprinted polyaniline membranes onto reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) modified glassy carbon (GC) electrode for dapsone (DDS) determination. The prepared RGO/AuNPs/PANI‐MIPs nanocomposite was characterized by Ultra‐Violet‐Visible (UV‐Vis), Fourier transform infrared spectroscopy (FT‐IR) and scanning electronic microscopy (SEM) images. The feature of the imprinted electrode was evaluated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and impedance spectroscopy (IS). Throughout this study several analytical parameters, such as incubation time, pH value, concentration of monomer/template molecules and electro‐polymerization cycles were investigated. Under the optimized conditions, the experimental results showed best analytical performances for DDS detection with a sensitivity of 0.188 Ω/mol L?1, a linear range from 1.0×10?7 M to 1.0×10?3 M and a detection limit of 6.8×10?7 M. The bioanalytical sensor was applied to the determination of dapsone in real samples with high selectivity and recovery. 相似文献