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101.
We use a pair of copper-vapor lasers in the oscillator–amplifier configuration for investigating the small-signal gain and the intensity saturation as the amplifying parameters, versus the pressure of various types of buffer gases. We show that the small-signal gain increases and the intensity saturation decreases with increase in the air pressure. Moreover, the values of these parameters are different for various gases used in the amplifier media. We show that both parameters are greater at the atmosphere of neon as a buffer gas than that of a mixture of helium and neon or air. 相似文献
102.
Ttrans‐3,5‐dihydroperoxy‐3,5‐dimethyl‐1,2‐dioxalane has been used as new, effective, solid, inexpensive and nontoxic oxidant for in situ generation of Br+ from HBr. This system has been applied as catalyst for synthesis of 2‐aryl‐1H‐benzothiazoles and 2‐aryl‐1‐arylmethyl‐1H‐benzimidazoles at room temperature in excellent yields and high purity. 相似文献
103.
Seyyed Javad Sabounchei Faeze Kazemi Andalib Marjan Hosseinzadeh Asieh Sedghi Ali Hashemi Roya Karamian Kristof Van Hecke 《应用有机金属化学》2020,34(1):e5265
The new α-keto-stabilized phosphorus ylide Ph3PCHC(O)PhCN ( Y ) was synthesized by addition of triphenylphosphine to 2-bromo-4′-cyanoacetophenone, followed by treatment with NaOH 10%. Reaction of ligand ( Y ) with methanolic solution of mercury(II) halides under mild conditions yielded the binuclear complexes [Y·HgX2]2 [X=Cl ( 1 ), Br ( 2 ), I ( 3 )]. The new organic/inorganic composite polymer [Hg(NO3)2(Y)]n ( 4 ) was synthesized by the reaction of mercury(II) nitrate with the phosphorus ylide Y . Compounds synthesized were characterized by Fourier-transform infrared, 1H, 31P, and 13C nuclear magnetic resonance spectroscopic methods, which confirmed the coordination of ylide to the metal center through the ylidic carbon atom. Single-crystal X-ray structures of phosphorus ylide Y and polymeric complex 4 were also determined and the crystallographic data of complex 4 showed that the title complex has an infinite one-dimensional structure. Furthermore, the electronic and molecular structures of complexes 1 – 3 were investigated at the BP86/def2-SVP level of theory, indicating an increasing trend for C→M bond lengths: Hg2I2 > Hg2Br2 > Hg2Cl2 in [Y→HgX2]2 (X = Cl, Br, I) complexes. In addition, the antibacterial activity of ligand Y and all complexes using the agar disc diffusion method was examined against both selected gram-positive and gram-negative bacteria. Results indicated that the ligand Y and complexes 1 and 4 show good antibacterial effect against gram-positive bacteria tested; besides, the inhibition zones of complexes were significantly larger than those of chloramphenicol as standard. 相似文献
104.
Hydride generation atomic absorption spectrometric determination of bismuth after separation and preconcentration with modified alumina 总被引:1,自引:0,他引:1 下载免费PDF全文
Farid Shakerian Ali Mohammad Haji Shabani Shayessteh Dadfarnia Mahboubeh Kazemi Avanji 《Journal of separation science》2015,38(4):677-682
A simple and sensitive method has been developed for the trace determination of bismuth in aqueous samples by a combination of solid‐phase extraction and hydride generation atomic absorption spectrometry. The method is based on the use of a column packed with 2‐mercaptobenzothiazole immobilized on sodium dodecyl sulfate coated alumina. Different parameters influencing the separation and preconcentration of bismuth such as pH, sample volume, type, and concentration of eluent, and the flow rate of sample and eluent were studied. A sample volume of 500.0 mL resulted in a preconcentration factor of 100. The precision (relative standard deviation, N = 10) at the 300 ng/L level and the limit of detection (3s) were found to be 2.3% and 12 ng/L, respectively. The developed method was successfully applied to the determination of bismuth in natural water samples and two certified reference materials. 相似文献
105.
G. H. Rounaghi M. H. Arbab Zavvar K. Badiee F. Boosaidi M. S. Kazemi 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(3-4):363-369
The equilibrium constants and thermodynamic parameters for complex formation of 18-crown-6(18C6) with Zn2+, Tl+, Hg2+ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations have been determined by conductivity measurements in acetonitrile(AN)-dimethylformamide(DMF) binary solutions. 18-crown-6 forms 1:1 complexes [M:L] with Zn2+, Hg2+ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations, but in the case of Tl+ cation, a 1:2 [M:L2] complex is formed in most binary solutions. The thermodynamic parameters ( $ \Delta {\text{H}}^{ \circ }_{{\text{c}}} $ and $ \Delta {\text{S}}^{ \circ }_{{\text{c}}} $ ) which were obtained from temperature dependence of the equilibrium constants show that in most cases, the complexes are enthalpy destabilized but entropy stabilized and a non-monotonic behaviour is observed for variations of standard enthalpy and entropy changes versus the composition of AN/DMF binary mixed solvents. The obtained results show that the order of selectivity of 18C6 ligand for these cations changes with the composition of the mixed solvent. A non-linear relationship was observed between the stability constants (logKf) of these complexes with the composition of AN/DMF binary solutions. The influence of the $ {\text{ClO}}^{ - }_{{\text{4}}} $ , $ {\text{NO}}^{ - }_{{\text{3}}} $ and $ {\text{Cl}}^{ - } $ anions on the stability constant of (18C6-Na+) complex in methanol (MeOH) solutions was also studied by potentiometry method. The results show that the stability of (18C6-Na+) complex in the presence of the anions increases in order: $ {\text{ClO}}^{ - }_{{\text{4}}} $ > $ {\text{NO}}^{ - }_{{\text{3}}} $ > $ {\text{Cl}}^{ - } $ . 相似文献
106.
G. H. Rounaghi M. S. Kazemi H. Sadeghian 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):79-83
The bulk liquid membrane transport of silver (I) ion was studied by dibenzopyridino-18-crown-6(DBPY18C6), 4-nitrobenzo-15-crown-5(NB15C5),
2-aminothiaphenol and a new synthesized ligand, 1,4-dioxa-7,10-dithiacyclododecane-2,3-dione as carriers in nitrobenzene (NB).
The effects of pH on the source phase and receiving phase, the nature and concentration of stripping agents in the receiving
phase and the picrate concentration as counter ion in source phase were investigated. The results show that the efficiency
of transport of the Ag+ ion through membranes, changes with the nature of the ligand. The efficiency transport increases for the ligands with donating
nitrogen and sulfur atoms with respect to oxygen donor atoms. Maximum transport efficiency was observed for silver (I) ion
in the presence of thiosulfate ion (
) as a suitable stripping agent. The results show that the sequence of transport efficiency for Ag+ ion using DBPY18C6, NB15C5, 2-aminothiaphenol and 1,4-dioxa-7,10-dithiacyclododecane-2,3-dione as carriers in organic solvents
is: nitrobenzene > dichloromethane > 1,2- dichloroethane > chloroform. 相似文献
107.
108.
J. Rafiei J. Sabbaghzadeh I. Mashayekhe Asl S. Sh. Kazemi 《Optics Communications》2010,283(18):3469-3474
A study of the thermo-mechanical analysis in edge-pumped composite Yb:YAG disk laser is presented. A three-dimensional model of disk and cooling system was created in ANSYS software. Heat load density applied on active medium was 14.6% of power absorption density. Temperature, stress and strain analysis showed a uniform distribution in the upper surface and maximum in the center. Finally, optimum heat exchanger coefficient and temperature of cooling system were obtained by comparing with different analyses and results. 相似文献
109.
Mohammad Mahdi Najafpour Małgorzata Hołyńska Mojtaba Amini Sayed Habib Kazemi Tadeusz Lis Mojtaba Bagherzadeh 《Polyhedron》2010
Two new silver(I) complexes ((tptz)Ag2(NO3)2 and [Ag5(tptz)4](NO3)5) with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) have been synthesized and characterized by X-ray diffraction, elemental analysis, 1H NMR, IR, fluorescence, UV–Vis spectroscopy and electrochemistry. Oxidation of alcohols to their corresponding aldehydes and ketones was conducted with one of the Ag complexes as a catalyst, soluble enough in organic solvent, using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature. 相似文献
110.
The interaction between α‐amylase from Bacillus subtilis and cetyltrimethylammonium bromide (CTAB) has been investigated at various temperature conditions using fluorescence and circular dichroism (CD) spectroscopic methods. Fluorescence data revealed that the fluorescence quenching of α‐amylase by CTAB is the result of complex formation between CTAB and α‐amylase. The thermodynamic analysis on the binding interaction data shows that the interactions are strongly exothermic (ΔH°=−17.92 kJ mol−1) accompanied with increase in entropy (ΔS° between 109 to 135 J mol−1 K−1). Thus the binding of CTAB to α-amylase is both enthalpic and entropic driven, which represent the predominate role of both electrostatic and hydrophobic interactions in complex formation process. The values of 2.17×10−3 M−1 and 1.30 have been obtained from associative binding constant (Ka) and stoichiometry of binding number (n), from analysis of fluorescence data, respectively. Circular dichroism spectra showed the substantial conformational changes in secondary structure of α‐amylase due to binding of CTAB, which represents the complete destruction of both secondary and tertiary structure of α-amylase by CTAB. 相似文献