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排序方式: 共有410条查询结果,搜索用时 15 毫秒
81.
Bahram Ghalami-Choobar Vahid Mahdavi Shadfar Pourpanah 《Journal of solution chemistry》2012,41(1):89-99
In this work mean activity coefficient measurements for KCl in the KCl + formamide + water system, using the potentiometric
method, are reported. The electromotive force measurements were performed on a galvanic cell of the type Ag | AgCl | KCl (m), formamide (w%), H2O (1−w)% | K-ISE, in solvent mixtures containing w=(0,10,20,30, and 40)% mass percent of formamide over ionic strengths ranging from 0.0010 to 3.9578 mol⋅kg−1. Modeling of the activity coefficients of this ternary system was based on an extended Debye–Hückel equation and the Pitzer
ion-interaction model. The resulting values of the mean activity coefficients, the osmotic coefficients and the excess Gibbs
energy, together with Pitzer ion-interaction parameters (β
(0), β
(1) and C
ϕ
) and Debye–Hückel parameters (a, c and d), are reported for the investigated system. 相似文献
82.
Chemical speciation (extraction of elemental information and identification of molecular environment for an analyte in a complex sample) has been a long sought after goal for analytical chemists. Recently, because of successful developments in more sensitive element-specific detectors and gentle separation schemes, which preserve the true chemical information in a real sample, routine speciation experiments are becoming a common occurrence in the scientific literature. For many reasons, the combination of capillary electrophoresis (for separation of different chemical species) with inductively coupled plasma mass spectrometry (for element and isotope specific detection) has emerged as the method of choice for these analyses. In this article the basic principles of capillary electrophoresis inductively coupled plasma mass spectrometry are discussed. Design consideration for instrument interface, anticipated difficulties with speciation experiments and applications for specific matrices and analytes are also presented in this article. 相似文献
83.
Two new complexes of [Mn(2-MPyzCI)2Cl2].H2O (1) and [Mn(2-MPyzCI)2(H2O)2](NO3)2 (2) were synthesized from the reaction of MnX2.4H2O (X=Cl? and NO3?) with 2-cyanopyrazine in methanolic solution. The chelating methyl pyrazine-2-carboximidate (2-MPyzCI) ligand is formed via the methanolysis of 2-cyanopyrazine. Although coordination environment around manganes(II) ions is similar, but these complexes are different in geometrical position of 2-MPyzCI ligands. As both compounds are synthesized under the same reaction conditions, the only difference between these two complexes are counter ions and changing of geometrical position of ligands can be considered as a result of influence of the counter-anions on the molecular structures. 相似文献
84.
Rezaei Shokoofe Rahpeima Soraya Esmaili Javad Javanbakht Vahid 《Russian Journal of Applied Chemistry》2021,94(4):533-548
Russian Journal of Applied Chemistry - Magnetic nanoparticles and clay minerals combine to form a class of advanced nanocomposites that would possess exceptional adsorption, magnetism, and... 相似文献
85.
Masoud Homayouni-Tabrizi Ehsan Karimi Farideh Namvar Mozhgan Soltani Vahid Pouresmaeil 《Research on Chemical Intermediates》2018,44(11):6537-6548
The aim of the present study is to evaluate the antioxidant and proapoptotic effects of silver–palm pollen (Ag/PP) nanocomposite. The percentage of live cells after treatment with various concentrations of Ag/PP (0, 5, 10, 20, and 40 µM/mL) was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. The antioxidant potential of Ag/PP was measured via the scavenging effects of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and molecular analysis. Apoptosis was assessed by morphological analysis, fluorescent dye, and flow cytometry, and its fundamental mechanism studied based on evaluation of Bax and Bcl2 gene expression. Ag/PP nanocomposite suppressed the viability of MCF-7 cells (dose and time dependently) and showed antioxidant properties. Morphological changes associated with cell death were observed in treated cells. Accumulation of dead cells in sub-G1 phase confirmed the occurrence of apoptosis in exposed cells. In addition, NPs induced cell death by altering Bcl-2 expression in MCF-7 cells. These results indicate that Ag/PP nanocomposite is an effective combination for removal of cancer cells by induction of apoptosis and could be useful for human health due to its antioxidant effects. 相似文献
86.
The reaction of solution 2,6‐pyridinedicarboxylic acid ( 1 ) and 2,2′‐Bipyridine with Pb(NO3)2 led to the coordination polymer [Pb(pydc)]n ( 2 ) (pydcH2 is 2,6‐pyridinedicarboxylic acid). This complex was characterized by elemental analysis, IR spectroscopy and single‐crystal structure of 2 . Crystal data for 2 at ?80 °C: monoclinic, space group P21/n, a = 977.2(1), b = 554.0(1), c = 1425.3(2) pm, β = 104.75(1)°, Z = 4, R1= 0.0261. The units [Pb(pydc)] form infinite chains along [010]. 相似文献
87.
Pt(II) complexes immobilized on polymer‐modified magnetic carbon nanotubes as a new platinum drug delivery system 下载免费PDF全文
Seyed Jamal Tabatabaei Rezaei Ali Hesami Hossein Khorramabadi Vahid Amani Asemeh Mashhadi Malekzadeh Ali Ramazani Hassan Niknejad 《应用有机金属化学》2018,32(7)
We combine nanotechnology and chemical synthesis to create a novel multifunctional platinum drug delivery vehicle based on magnetic carbon nanotubes (multiwall carbon nanotubes/Fe3O4@poly(citric acid)/cis‐[(Pt(1,7‐phenanthroline)(DMSO)Cl2)]‐b‐poly(ethylene glycol) (MCNTs/FO@PC/Pt(II)‐b‐PEG)) for targeted cancer therapy. MCNTs/FO@PC/Pt(II)‐b‐PEG was conveniently prepared by conjugating cis‐[Pt(1,7‐phenanthroline)(DMSO)Cl2] complex to MCNTs/FO@PC‐b‐PEG via strong hydrogen‐bonding interactions. In comparison with free cisplatin and Pt(II) complex, MCNTs/FO@PC/Pt(II)‐b‐PEG shows higher solubility in aqueous solution and higher cytotoxicity towards human cervical cancer HeLa cells and human breast cancer MDA‐MB‐231 cells. In vitro release experiments revealed that the platinum drug‐loaded delivery system is relatively stable under physiological conditions (pH = 7.4 and 37 °C) but susceptible to acidic environments (pH = 5.6 and 37 °C) which would trigger the release of loaded drugs. Fluorescence microscopy studies revealed that this magnetic nanohybrid system possesses marked cell‐specific targeting in vitro in the presence of an external magnetic field. The results indicated that the prepared superparamagnetic MCNTs/FO@PC/Pt(II)‐b‐PEG nanohybrid system is a promising candidate for inhibiting the proliferation of cancer cells. 相似文献
88.
Synthesis of pH‐responsive magnetic yolk–shell nanoparticles: A comparison between conventional etching and new deswelling approaches 下载免费PDF全文
Iron oxide (Fe3O4) magnetic nanoparticles as movable cores were used to synthesize yolk–shell nanoparticles with pH‐responsive shell composed of ethylene glycol dimethacrylate (EGDMA)‐crosslinked poly(acrylic acid) (PAA) via two different routes. In the first more common route, Fe3O4 nanoparticles were coated with silica layer via the Stöber process to yield Fe3O4@SiO2 core–shell nanoparticles, subsequently used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@SiO2@P(AA‐EGDMA). The silica layer was selectively removed through alkali etching to yield Fe3O4@air@P(AA‐EGDMA). In the second route, Fe3O4 nanoparticles without any stabilization were used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@P(AA‐EGDMA) core–shell nanoparticles. The nanoparticles were subsequently dispersed in acidic medium of pH = 2. Yolk–shell Fe3O4@air@P(AA‐EGDMA) nanoparticles were formed through deswelling of crosslinked PAA because of protonation of carboxyl groups at low pH values. Various techniques were utilized to investigate the characteristics of the synthesized core–shell nanoparticles. Formation of yolk–shell nanostructure was observed for both synthesis routes, namely etching of silica layer and deswelling approaches, from vibrating sample magnetometry and transmission electron microscopy results. Both types of nanoparticles showed pH‐responsive behaviour, i.e. decrease in absorption with increase in pH, as examined using UV–visible spectroscopy. 相似文献
89.
We show that the xxz Heisenberg magnet withlong-range interactions in a magnetic field, isintegrable both classically and quantum mechanically.Explicit expressions are given for the involutiveintegrals of the motion. The nature of the spectrum andthe ground state are clarified and the partitionfunction is calculated exactly in the thermodynamiclimit. A detailed study of the phase structure of thesystem is also performed. 相似文献
90.
Saleh Shahin Pirouzfar Vahid Alihosseini Afshar 《Journal of Thermal Analysis and Calorimetry》2019,136(4):1817-1830
Journal of Thermal Analysis and Calorimetry - In this study, a refrigeration cycle was simulated with different refrigerants in a petrochemical plant in Iran. Using Aspen HYSYS Software, necessary... 相似文献