نشریه علوم دانشگاه خوارزمی
سال یازدهم شماره 3 (پاییز 1390)

In this paper nanoparticles of lithium-cobalt oxide on alumina and silica substrates, by sol-gel method and with citric acid as gelling agent were prepared. The effects of different substrates on size, shape and catalytic effects of nanoparticles were studied. To evaluate the catalytic activity, rate of decomposition of hydrogen peroxide in the presence of any of the samples by measuring the volume of oxygen gas released at the time, was investigated. The X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and FT-IR spectra confirmed the formation of Co3O4 and LiCoO2 phases

An efficient, mild and environmentally- friendly approach was developed for the synthesis of bis arylidine cycloalkanones. SnCl4 was found as efficient catalyst for cross aldol condensation of cycloalkanones and aromatic aldehyde for synthesis of α,α'-bis(substituted-benzylidine) cycloalkanones in ethanol as a green solvent. In this method, the reaction works easily for a variety of aldehydes with both electron-donating and electron-with-drawing groups to give corresponding α,α’-bis(substituted-benzylidene) cyclohexanones in good to excellent yields. Comparing the known methods, the main advantages of our method are short time, user-friendly, low cost procedure, clean and environmentally benign reagents with ease of separation of the product and mild reaction condition with good to excellent yield for products

A simple hydrothermal method was designed for the synthesis of the nanostructure Barium phosphonate in presence of cetyltrimethylammonium bromide (CTAB) or sodium dodecyl sulfate (SDS) as surfactant. FT-IR, EDAX, XRF, XRD, SEM were used to characterize this material. Effect of solvent on morphology complex was discussed. Thermogr avimetric analysis (TGA) shows the existence of porosity and stability of the material.

In this research, we are going to study of QCD penguin structure and calculated the second order approximation. The amplitude of decays related to QCD penguin in quark model up to the first and second orders calculated. We calculated the amplitude of QCD penguin on lowest order of for first order of the decay processes and for second order of the decay processes. We calculated the decay rates of the first and second order of QCD penguin for various b quark decays. We consider that, the second order of QCD penguin of b quark decays is much smaller than the first order of them. In the other hand, we can ignore the second order of QCD penguin in the b quark decays. We deduced various two and three body decays of B meson decays from various decays of b quark model. We compared the branching ratios of various decays of B meson, theoretically and experimentally and saw that the second order of QCD penguin term in b quark decays is small.

Conducting polyaniline (PANI) nano particles doped with HCl were synthesized by a sonochemical method. Polyaniline/Poly (styrene- alt-maleic acid)/Polystyrene sulfonic acid nano composites with different polyaniline content were developed by solution-dispersion blending method. The influence of Poly (styrene-alt-maleic acid) (PSMAC) and polystyrene sulfonic acid (PSS) concentration in nano composite structure was investigated. The composite dispersed solution in tetrahydrofurane (THF) cast to fabricate conductive films with evaporation of the solvent. With only a mixing procedure and without any dispersant added, the PANI nanoparticles were well dispersed in the matrix polymer as indicated by scanning electron microscopy (SEM) images. The conductivity of obtained nano composites was measured with four probe technique. All of obtained nano composites have conductivity and between them, the maximum electrical conductivity was 3 S/cm. The obtained nano composites were characterized by FT-IR and UV-Vis spectroscopiess.

In this paper, we analyze, near infra red images of the central region of the local group galaxy M33. These images were obtained in K band with the UFTI instrument, installed on the UKIRT telescope. This is a part of a bigger project started in 2003 with an aim to investigate RGB and AGB stars in M33. K band magnitude was obtained for 18509 stars by fitting appropriate PSF models to stellar profiles in the images. ‎The ‎final ‎catalogue ‎was ‎obtained ‎by calibrating ‎instrumental ‎magnitude ‎to ‎standard‎ ‎system.‎ Cross correlation methods was manipulated to assign J-K color index to each star. A color magnitude diagram was plotted which represents population of RGB, AGB and Carbon stars in the core of M33 galaxy