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21.
Ghashghaee Mohammad Shirvani Samira Farzaneh Vahid 《Russian Journal of Applied Chemistry》2017,90(2):304-309
The selective hydrogenation of furfural has been investigated over the titania-supported monometallic (Cu) and bimetallic (Cu–Cr) catalysts. The catalytic performances were assessed over 4 h of run length under atmospheric pressure at the hydrogen-to-hydrocarbon ratio of 10.6 and 453 K. The results represented that the level of furfural conversion over the non-promoted catalyst was very low (below 10%) while the promoted one showed considerable furfural conversion during this period (higher than 70%). However, both catalysts exhibited high durability and selectivity towards furfuryl alcohol.
相似文献22.
B. B. Shirvani M. B. Shirvani J. Beheshtian N. L. Hadipour 《Journal of the Iranian Chemical Society》2011,8(1):S110-S118
Behavior of a single CH4 molecule adsorbed on external surface of H-capped (4,4) (5,5), (6,6) and (5,0) single-walled carbon nanotubes (SWCNTs) is studied via B97D hybrid density functional and 6-31G* basis set. Binding energies clearly exhibit adsorption dependence on tube diameter. 13C and 1H chemical shielding tensors are calculated at the B971 level using GIAO method. The 1H and 13C(CH4) NMR results reveal that chemical shielding due to CH4 molecule adsorption are also dependent upon the nanotube electronic structure, and radius. 2H nuclear quadrupole coupling constants, C Q, and asymmetry parameter, η, reveal the remarkable effect of CH4 adsorption on electronic structure of the SWCNTs. 相似文献
23.
Quantum regime of a plasma‐wave‐pumped free‐electron laser in the presence of an axial magnetic field 下载免费PDF全文
The quantum regime of a plasma‐whistler‐wave‐pumped free‐electron laser (FEL) in the presence of an axial‐guide magnetic field is presented. By quantizing both the plasma whistler field and axial magnetic field, an N‐particle three‐dimensional Hamiltonian of quantum‐FEL (QFEL) has been derived. Employing Heisenberg evolution equations and introducing a new collective operator which controls the vertical motion of electrons, a quantum dispersion relation of the plasma whistler wiggler has been obtained analytically. Numerical results indicate that, by increasing the intrinsic quantum momentum spread and/or increasing the axial magnetic field strength, the bunching and the radiation fields grow exponentially. In addition, a spiking behavior of the spectrum was observed with increasing cyclotron frequency which provides an enormous improvement in the coherence of QFEL radiation even in a limit close‐to‐classical regime, where an overlapping of these spikes is observed. Also, an upper limit of the intrinsic quantum momentum spread which depends on the value of the cyclotron frequency was found. 相似文献
24.
Javad Beheshtian Hadi Behzadi Mehdi D. Esrafili Bahram B. Shirvani Nasser L. Hadipour 《Structural chemistry》2010,21(5):903-908
The effect of water molecule adsorption on the surface of (5,0) zigzag boron nitride nanotube was studied by density functional
theory calculations. Geometrical optimizations were carried out at the B3LYP/6-31+G* level of theory. Six different configurations
of water molecule(s) adsorption process including monomer (1WB and 1WN), dimer (2WB, 2WNN, and 2WBN), and trimer (3WB) clusters
were obtained. The strengths of interactions were analyzed by the equilibrium geometries, binding energies, and charge transfer.
The natural bonding analysis was also performed to investigate electronic properties. The results reveal that the adsorption
of water is more favorable as the water cluster size increases. 相似文献
25.
Nader Saemian Gholamhossein Shirvani Sayed Sajad Oliyaee Mohsen Javaheri 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):237-241
The key synthetic intermediate, (2-mercapto-1-(4-nitrobenzyl)-1H-imidazol-5-yl)methanol-[2-14C], has been synthesized by using one pot procedure from potassium[14C]-thiocyanate. It was converted to two nonpeptide angiotensin II receptor antagonists, 2-methylthio-1-[4-N-α-ethoxycarbonyl
benzyl)-aminobenzyl]-5-hydroxymethyl-1H-imidazole-[2-14C] and 1-[4-N-α-ethoxy-carbonylbenzyl)-aminobenzyl]-5-hydroxymethyl-1H-imidazole-[2-14C] via a 3-step sequence synthetic pathway. 相似文献
26.
Nader Saemian Gholamhossein Shirvani Mohsen Javaheri 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):421-423
Aryl N-alkoxycarbamates labeled with carbon-14 have been synthesized from aryl nitrile-[cyano-14C] as part of a 2-step sequence. The resulted carbamates were treated with amines, generating [carbonyl-14C]-Ureas in high yield and purity. 相似文献
27.
We define HNN-extensions of Lie algebras and study their properties. In particular, a sufficient condition for freeness of subalgebras is obtained. We also study differential HNN-extensions of associative rings. These constructions are used to give short proofs of Malcev's and Shirshov's theorems that an associative or Lie algebra of finite or countable dimension is embeddable into a two-generator algebra.
28.
We show that for a surjective endomorphism of a compact abelian group ergodicity is equivalent to a condition which impliesr-mixing for allr1, and we characterize such maps algebraically. This is then used in proving the ergodicity of an extensive class of endomorphisms of the binary sequence space. As a simple corollary it is found that one-dimensional linear cellular automata and the accumulator automata arer-mixing for allr1.This work was supported in part by grants from NSERC 相似文献
29.
N. Saemian G. Shirvani H. Matloubi 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(3):643-645
N-(3,5-Dichlorobenzyl)-4-(fluoromethoxy) benzenecarboximidamide labeled with carbon-14 was prepared from 4-hydroxy-benzonitrile-[cyano-14C]. 相似文献
30.
M. Shirvani H. Van Roessel 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1992,43(3):526-535
Summary It is proved that for the general bilinear kernel with arbitrary initial conditions, the solutions to the discrete coagulation equation can exhibit one of the following types of behaviour: conservation of mass for all time, conservation of mass for a finite time only, or instantaneous gelation.Research supported in part by grants from Natural Sciences and Engineering Research Council of Canada. 相似文献