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排序方式: 共有813条查询结果,搜索用时 31 毫秒
61.
A highly efficient synthesis of 2‐arylamino‐2‐imidazolines and 2‐aminobenzimidazoles from aminoimino‐methanesulfonic acid derivatives is described. The method is simple and practical, generating imidazoline and benzimidazoline derivatives in excellent isolated yields. 相似文献
62.
S. Hosseini M. HomaieeA.B. Mohamad M.R. MalekbalaA.A.H. Khadum 《Physica B: Condensed Matter》2011,406(9):1689-1694
Cesium dihydrogen phosphate (CDP) nanoparticles were synthesized using the surfactants cetyltrimethyl ammonium bromide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and (F-68:CTAB) with molar ratio 0.06. The samples conductivity such as CDPCTAB, CDPF-68 and CDP(F-68:CTAB)0.06 was studied by impedance spectroscopy in the frequency range 0.01 Hz to 1 MHz. The Nyquist plots were drawn at different temperatures of 210, 230 and 260 °C, which are defined below transition, phase transition and above transition, respectively. The measured conductivities obey the Arrhenius relation. The influence of surfactants on conductivity are more significant at higher temperature due to grain boundary. The conductivity of CDPCTAB increased slightly with increasing temperature to 260 °C, whereas the conductivity of other samples decreased with increasing temperature over 230 °C. The results indicated that the conductivities increase in the order of CDPCTAB>CDP(F-68:CTAB)0.06>CDPF-68. These are in accordance to the ion exchange capacities of the samples that the surfactant shows a direct influence on the samples proton mobility. It is found that the conductivity of CsH2PO4 is influenced by surfactant type. 相似文献
63.
Hassan Hosseini Monfared Azar Mohajeri Ali Morsali Christoph Janiak 《Monatshefte für Chemie / Chemical Monthly》2009,17(1):1437-1445
Abstract
The Mn(II) dicarboxylate coordination polymers [Mn(μ-terephthalate)(H2O)2] n , [Mn(μ-oxalate)(H2O)2] n , and [Mn(μ-d-(−)-tartrate)] n were prepared in water and characterized by FT-IR spectroscopy and CHN analysis. Particles of the terephthalate catalyst were also synthesized, by reaction of terephthalic acid and MnCl2·4H2O by a sonochemical method. The catalytic potential of these coordination polymers as slow-release sources of catalytically active Mn species was tested in the oxidation of cyclooctene to its epoxide in acetonitrile, using hydrogen peroxide as oxygen source. For the terephthalate species the catalytic activity was found to increase with increasing dielectric constant and dipole moment of the solvent (being highest in acetonitrile), with reaction temperature to a maximum at 60 °C, and with an imidazole co-catalyst (highest activity found for a imidazole-to-catalyst molar ratio of 20:1). Good activity with more than 64% conversion in 24 h was obtained for epoxidation of cyclooctene and cyclohexene, whereas low yields only were obtained from aryl-substituted olefins. Some exo versus endo regioselectivity was found for norbornene. 相似文献64.
Forming partnerships in a virtual factory 总被引:1,自引:0,他引:1
65.
Quantum chemical methods are becoming ever more prevalent for assessing surface interactions of different molecules using cluster models and semi-empirical, ab initio Hartree–Fock and density functional theory (DFT) studies considering the standard potential energy surfaces. Examination of the efficacy of some pyridine derivatives to counter aluminium corrosion in hydrochloric acid using ab initio and semi-empirical quantum chemical deductions and its comparison with the available experimental data forms the basis of this research. It is believed that the inhibition efficiency has lucid correlation with the total energy of inhibitor molecules and highest occupied molecular orbital energy levels calculated by DFT study methods and thus the adsorption energy for the pyridine on Al1, Al5, Al14, Al18 and Al26 clusters are determined to assess the convergence of the results with respect to size of the cluster. Subsequently, Al26 is used for the inhibitor/aluminium cluster interface investigations. Results highlight the reaction between pyridine molecules and appropriately active sites such as corners and steps or kinks and screw dislocations towards which pyridine molecules are attracted as is evident from a three times rise in adsorption energy from (−35) to (−107) kJ mol−1. Therefore, inhibition mechanism is primarily associated with local properties. Interactions take place between the surface defect and the nitrogen group of the pyridine molecule however, the possibility of ion pair formation between protonated pyridine and chloride ion and its influence on the general adsorption of pyridine on aluminium is also examined. The interaction energies of pyridine and aluminium cluster with the natural bond orbital are also reported. 相似文献
66.
Dadkhah Davood Zomorodi Mariam Hosseini Seyed Ebrahim 《International Journal of Theoretical Physics》2021,60(9):3271-3285
International Journal of Theoretical Physics - In the present work, a novel approach was proposed to optimize the teleportation cost in Distributed Quantum Circuits (DQCs) by applying a new... 相似文献
67.
Somayeh Hosseini Amir Charkhi Abdolhamid Minuchehr Seyyed Javad Ahmadi 《Chemical Papers》2017,71(6):1143-1153
Pervaporation (PV) separation of water–acetonitrile mixture using sodium alginate (NaAlg) based mixed matrix membranes (MMM) comprising different amounts of nano NaA zeolite (10, 20 and 30 wt%) is investigated in various concentrations of water and temperatures. The prepared membranes are modified by sulfosuccinic acid (SSA) as a crosslinking agent. NaAlg-NaA/SSA membranes are synthesized by a solution casting technique. The process and membrane performance including separation factor, flux and activation energy of permeation are determined. Results reveal that adding of nano zeolite may lead to an increase in the flux and the separation factor of sodium alginate membrane up to 123 and 169%. In addition, using MMM in dehydration of a feed containing 30 wt% of water shows much better performance than alginate membrane. Furthermore, the activation energy of water permeation through MMM is predicted lower than sodium alginate membrane which reflects the facilitated permeation of water through MMM. 相似文献
68.
Naser Seyed-Matin Amir Hossein Jalili Masih Hosseini Jenab Seyed Majid Zekordi Ali Afzali Chapar Rasouli Akbar Zamaniyan 《Plasma Chemistry and Plasma Processing》2010,30(3):333-347
The carbon dioxide reforming of methane to synthesis gas under DC-pulsed plasma was investigated. The effects of specific
input energy and feed ratio on the product distribution and also feed conversion was studied. At the input energy of about
11 eV/molecule per methane and/or carbon dioxide the feed conversion of 38% for CH4 and 28% for CO2 and product selectivity of 74% has been attained for H2 and CO at feed flow rate of 90 ml/min. The energy consumption in this work displays potential to further study and optimization
of the process. The importance of the electron impact reactions in the process was discussed. The results show that by prudent
tuning of system variables, the process be able to run in the way of synthesis gas, instead of hydrocarbon production. 相似文献
69.
S. Masoud Hosseini A. R. Moghadassi D. Henneke Ali Elkamel 《Journal of Thermal Analysis and Calorimetry》2010,101(1):113-118
Changes in the thermal conductivities of paraffin and mono ethylene glycol (MEG) as a function of β-SiC nanoparticle concentration
and size was studied. An enhancement in the effective thermal conductivity was found for both fluids (i.e., both paraffin
and MEG) upon the addition of nanoparticles. Although an enhancement in thermal conductivity was found, the degree of enhancement
depended on the nanoparticle concentration in a complex way. An increase in particle-to-particle interactions is thought to
be the cause of the enhancement. However, the enhancement became muted at higher particle concentrations compared to lower
ones. This phenomenon can be related to nanoparticles interactions. An improvement in the thermal conductivities for both
fluids was also found as the nanoparticle size shrank. It is believed that the larger Brownian motion for smaller particles
causes more particle-to-particle interactions, which, in turn, improves the thermal conductivity. The role that the base-fluid
plays in the enhancement is complex. Lower fluid viscosities are believed to contribute to greater enhancement, but a second
effect, the interaction of the fluid with the nanoparticle surface, can be even more important. Nanoparticle-liquid suspensions
generate a shell of organized liquid molecules on the particle surface. These organized molecules more efficiently transmit
energy, via phonons, to the bulk of the fluid. The efficient energy transmission results in enhanced thermal conductivity.
The experimentally measured thermal conductivities of the suspensions were compared to a variety of models. None of the models
proved to adequately predict the thermal conductivities of the nanoparticle suspensions. 相似文献
70.
S. Hosseini A. B. Mohamad A. H. Kadhum W. R. Wan Daud 《Journal of Thermal Analysis and Calorimetry》2010,99(1):197-202
A study concerned to thermogravimetric analysis is performed in cesium dihydrogen phosphate (CsH2PO4) that was synthesized, using cetyltrimethylammonium-bromide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and mixture of
(F-68:CTAB) with two mole ratio 0.06 and 0.12 as surfactant. The dehydration behavior of particles was studied using thermal
gravimetric analysis and differential scanning calorimetric. Subsequently, the experimental results indicated that the first
dehydration temperature in the range of 237–239 °C upon heating, the second peaks occur at temperature range 290–295 °C and
overlapping in the thermogravimetric events is observed. The mass loss values are obtained in the range of 6.62–6.97 wt% that
is less than reported theoretical value 7.8 wt%. These values show well compatibility of reaction CsH2PO4 to Cs2H2P2O7 with 3.92 wt% whereas mass loss value of CsH2PO4 to CsPO3 is less than theoretical value 7.8 wt%. The activation energy of two steps dehydration are calculated using Kissinger equation
for the samples synthesized via CTAB and (F-68) with minimum value mass loss 6.62% and maximum value mass loss 6.97%, respectively.
The calculation results reveal that the reaction rate in the first step (CsH2PO4 → Cs2H2P2O7) is faster than the second step (CsH2PO4 → CsPO3). The weight loss values of the samples demonstrate that existence of CTAB can be considered as effective factor which prevents
more weight loss during the dehydration process. 相似文献