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731.
732.
In this article, the optical absorption coefficients in an asymmetric ridge quantum wire within the framework of the density matrix formalism are studied. The energy spectrum and wave functions of a quantum wire with graded confinement potential using the effective mass approximation are analytically calculated. The results show that parameters such as the asymmetry and width of the potential well change the position and magnitude of the absorption peak and saturation intensity. The incident optical intensity also has a great effect on the total absorption. 相似文献
733.
Effect of magnetic field on the impurity binding energy of the excited states in spherical quantum dot 总被引:1,自引:0,他引:1
The effect of external magnetic field on the excited state energies in a spherical quantum dot was studied. The impurity energy
and binding energy were calculated using the variational method within the effective mass approximation and finite barrier
potential. The results showed that by increasing the magnetic field, the energy would be increased. The results obtained by
this method were compared with the previous investigations. 相似文献
734.
Ehsan Zolfonoun Abolfazl Semnani 《International journal of environmental analytical chemistry》2013,93(5):327-336
A simple and fast method for preconcentration and determination of ultra trace amounts of lead(II), mercury(II) and cadmium(II) in water samples is presented. Lead, mercury and cadmium adsorbed quantitatively during passage of water samples (pH?=?7, flow rate?=?20 mL min?1) through octadecyl silica membrane disks modified with 5,5′-dithiobis(2-nitrobenzoic acid). The retained lead, mercury and cadmium are then stripped from the disk with a minimal amount of 1 M hydrochloric acid solution as eluent, and determined by atomic absorption spectrometry. The influence of flow rates of the eluent and sample solution, the amount of ligand, type and least amount of eluent, pH of sample, effect of other ions and breakthrough volume are determined. The breakthrough volume of the method is greater than 2000 mL for lead and greater than 1500 mL for mercury and cadmium, which results in an enrichment factor of 200 for lead and an enrichment factor of 150 for both mercury and cadmium. The limit of detection of the proposed method is 177, 2 and 13 ng l?1 for lead, mercury and cadmium, respectively. 相似文献
735.
Ehsan Zolfonoun Maryam Salahinejad 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1801-1807
A new simple and rapid vortex-assisted liquid–liquid microextraction method was applied for the determination of thorium in water samples. In this method, chloroform used as extraction solvent was directly injected into the water sample solution. The extraction solvent was dispersed into the aqueous phase under vigorously shaking with the vortex. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom centrifuge tube. The effect of different experimental parameters on the performance of the method were studied and discussed. Under the optimum conditions, the detection limit for Th(IV) was 7.5 ng mL?1. The precision of the method, evaluated as the relative standard deviation obtained by analyzing of 10 replicates, was 2.8 %. The practical applicability of the developed method was examined using natural water and monazite sand samples. 相似文献
736.
Mahdi Sadeghi Hamidreza Jabal-Ameli Seyed J. Ahmadi Sodeh S. Sadjadi Mohamadreza K. Bakht 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(1):45-49
198Au (??max?=?0.96?MeV (98.6?%), ??max?=?0.412?MeV (95.5?%) and T 1/2 ?=?2.7?days) is a radionuclide with very appealing characteristics. 198Au has been widely used to treat the uterus, bladder, cervix, prostate, melanoma, breast, skin and other cancers. In the present study, cationic 198Au+3 and nonionic 198Au0 are prepared following thermal neutron irradiation of commercially available natural gold compounds in Tehran Research Reactor via the natAu(n,??)198Au reaction. The prospects in the production of pure 198Au0 and 198Au+3 for radionuclide therapy are discussed and effect of reduction on the activity of radioactive gold is evaluated. Au0 particles were synthesized via NaBH4 reduction of aqueous solutions of hydrogen tetrachloroaurate trihydrate. Then two quartz tubes were charged with cationic 198Au3+ and nonionic 198Au0. After irradiation by thermal neutrons, the samples were analyzed for a period of 1?month by liquid scintillation counter and high purity germanium detector. As a result, natAu3+ reduction process had no significant effect on the activity of the 198Au sample. In conclusions, natural gold thermal neutron activation cross section is reasonably high for medical application. 相似文献
737.
K. Bitaghsir Fadafan B. Pourhassan J. Sadeghi 《The European Physical Journal C - Particles and Fields》2011,71(10):1785
In this paper we use the AdS/CFT correspondence to compute the jet-quenching parameter in a N=2\mathcal{N}=2 thermal plasma. We consider the general three-charged black hole and discuss several special cases. We add a constant electric
field to the background and find the effect of the electric field on the jet-quenching parameter. Also, we add higher derivative
terms and obtain the first-order correction of the jet-quenching parameter. 相似文献
738.
Morteza Sadeghi Ghader Khanbabaei Amir H. Saeedi Dehaghani Mohammad Sadeghi Mohammad A. Aravand Mohammad Akbarzade Somaieh Khatti 《Journal of membrane science》2008
The effect of silica nanoparticles on the gas separation properties of ethylene vinyl acetate (EVA) copolymer containing 28% vinyl acetate has been investigated. The EVA and hybrid EVA–silica membranes were prepared via thermal phase inversion method. Silica nanoparticles prepared by hydrolysis of tetraethylorthosilicate (TEOS), through the sol–gel mechanism. The prepared membranes were characterized using FT-IR, SEM, DSC and XRD methods. FT-IR and SEM results indicated the nanoscale dispersion of silica particles in polymer matrix. As confirmed by XRD and DSC analyses, increasing the silica content enhances the amorphous regions significantly. Gas permeation of EVA–silica nanocomposite membranes with silica contents of 5, 6 and 10 wt.% was studied for N2, O2, CO2 and CH4 single gases at pressures of 4, 6 and 8 bar. The obtained results suggest a significant increase in permeability of all gases and an increase in CO2/N2 and CO2/CH4 gases selectivities upon increasing the silica content. The possible reasons for such behavior were stated and discussed. The pressure dependence of the gas permeabilities of the membranes was also investigated. 相似文献
739.
M. R. Setare J. Sadeghi A. Banijamali 《The European Physical Journal C - Particles and Fields》2009,64(3):433-438
In this paper we show that power-law inflation can be realized in non-minimal gravitational coupling of electromagnetic field
with a general function of the Gauss–Bonnet invariant. Such a non-minimal coupling may appear due to quantum corrections.
We also consider modified Maxwell-F(G) gravity in which non-minimal coupling between electromagnetic field and f(G) occurs in the framework of modified Gauss–Bonnet gravity. It is shown that inflationary cosmology and late-time accelerated
expansion of the universe are possible in such a theory. 相似文献
740.
Shefa Mirani Nezhad Ehsan Nazarzadeh Zare Azimeh Davarpanah Seied Ali Pourmousavi Milad Ashrafizadeh Alan Prem Kumar 《Molecules (Basel, Switzerland)》2022,27(5)
Antibacterial materials have obtained much attention in recent years due to the presence of hazardous agents causing oxidative stress and observation of pathogens. However, materials with antioxidant and antibacterial activities can cause toxicity due to their low biocompatibility and safety profile, urging scientists to follow new ways in the synthesis of such materials. Ionic liquids have been employed as a green and environmentally solvent for the fabrication of electrically conductive polymers. In the present study, an antibacterial poly(p-phenylenediamine)@Fe3O4 (PpPDA@Fe3O4) nanocomposite was fabricated using [HPy][HSO4] ionic liquid. The chemical preparation of PpPDA@Fe3O4 nanocomposite was initiated through the oxidative polymerization of p-phenylenediamine by ammonium persulfate in the presence of [HPy][HSO4]. The PpPDA@Fe3O4 nanocomposite exhibited antibacterial properties against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria. The PpPDA@Fe3O4 nanocomposite was employed as a heterogeneous nanocatalysis for one-pot synthesis of polyhydroquinoline derivatives using aromatic aldehyde, dimedone, benzyl acetoacetate, and ammonium acetate. Polyhydroquinoline derivatives were synthesized in significant yields (90–97%) without a difficult work-up procedure in short reaction times. Additionally, PpPDA@Fe3O4 nanocatalyst was recycled for at least five consecutive catalytic runs with a minor decrease in the catalytic activity. In this case, 11 derivatives of polyhydroquinoline showed in vitro antioxidant activity between 70–98%. 相似文献