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101.
The effect of calcination temperature on the activity and some properties of low temperature water gas shift reaction catalysts
has been investigated. The activities of catalysts have been determined using a fixed bed catalytic reactor. The following
results may be deduced from the present study. 1. The catalysts' total surface area decreased with increasing calcination
temperature, presumably due to the partial sintering of the catalysts particles. 2. The presence of an amorphous CuO phase
within the structure of some catalysts may be related to the desirable conditions prevailing during synthesis of the latter.
3. Observation of a similar trend between the increase in copper crystallite particle size and enhancement of catalyst activities
with increasing calcination temperature demonstrates the important contribution made by the copper crystallite phase to the
overall activities of water gas shift reaction catalysts.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
102.
New nickel(II), copper(II), cobalt(III) and rohdium(III) complexes of two Schiff base ligands formed by condensation of furfural and benzil with S-benzyldithiocarbazate have been synthesized and characterized by elemental analysis and magnetic and spectroscopic measurements. The nickel(II) complexes, Ni(NS)2 and Ni(ONS)2 (NS and ONS stand for the uninegatively charged furfural and benzil Schiff bases, respectively) are square-planar and octahedral, respectively. The Cu(NS)Cl complex is paramagnetic with a magnetic moment fo 1.73 B.M. A halogen-bridged dimeric structure is proposed for this complex. The copper(II) complex, Cu(ONS)Cl is diamagnetic, suggesting strong antiferromagnetic interactions between a pair of copper(II) ions in a thiolo sulphur-bridged dimeric or polymeric structure. Cobalt(II) ions are oxidized in the presence of the Schiff bases with the concomitant formation of cobalt(III) complexes of empirical formulae, Co(NS)3, Co(ONS)2ClO4 and Co(ONS)2Cl, respectively, which are spin-paired and octahedral. The rhodium(III) complex of the furfural Schiff base, Rh(NS)2Cl is tentatively assigned a halogen-bridged dimeric structre. 相似文献
103.
104.
Ismat Beg Akbar Azam Faryad Ali Tahira Minhas 《Rendiconti del Circolo Matematico di Palermo》1991,40(2):307-315
The concept of a convex metric space was introduced by Takahashi [10]. He observed that it is possible to generalize fixed point theorems in Banach spaces. Subsequently, Machado [8], Itoh [5], Naimpally, Singh and Whitfield [9] and Beg and Azam [2], among others have studied fixed point theorems in convex metric spaces. This paper is a continuation of these investigations. 相似文献
105.
Safari Sinegani AA Emtiazi G Shariatmadari H 《Journal of colloid and interface science》2005,290(1):39-44
The interaction of organic molecules with mineral surfaces is a subject of interest in a variety of disciplines. Enzymes are able to be sorbed and immobilized by clay minerals and humic colloids in soil environment. The present study was done to elucidate some aspects of sorption and immobilization of cellulase on soil components by analysis of the sorption, and immobilization of cellulase on Avicel, a soil sample, illite, kaolinite, montmorillonite, and palygorskite. Palygorskite displayed the highest sorption capacity. Sorbents coated with hydroxyaluminum displayed significantly higher capacity than uncoated sorbents. The positive effects of Al(OH)(x) coating on sorption capacities of the different sorbents were not equal. The effect decreased in the order soil > palygorskite > kaolinite > Avicel > montmorillonite > illite. The amount of sorbed cellulase desorbed from external surfaces of soil was quite low (about 16%), especially in coated samples (about 6%). X-ray diffraction analysis of K-montmorillonite and Ca-montmorillonite showed that Al(OH)(x) was intercalated between the montmorillonite layers. Immobilization of cellulase on the sorbents did not result in expansion of their crystal structures. Therefore, it may be concluded that the amount of cellulase immobilized on internal surfaces of the sorbents was negligible. 相似文献
106.
The synthesis of the title compounds is described. Some of the compounds prepared were found to be active against a number of pathogenic microorganisms in vitro. 相似文献
107.
Mohamad Akbar Ali 《Molecular physics》2013,111(20):2149-2158
Cyclic [n]paraphenyleneacetylenes ([n]CPPAs) are potentially useful compounds for molecular electronics. In this article, a homodesmotic reaction scheme coupled with density functional theory has been used to estimate theoretically strain energies and heats of formation of [n]CPPAs. Calculations have been done for a series of [n]CPPAs, containing up to ten phenylacetylene units. Strain energies of [n]CPPAs decrease, while heats of formation increase steadily with the increase in the number of phenylacetylene units using homodesmotic reaction schemes. B3LYP and mPW1PW91 functionals have been used with the Pople basis set 6-31G* to analyze the trends. The results are sensitive to the scheme of homodesmotic reaction chosen, thereby necessitating careful chemical consideration before spending considerable computational resources for higher [n]CPPAs not considered here. Computational estimates for the ring diameter of [n]CPPAs and absolute entropy have also been obtained here. The HOMO-LUMO gaps of the belt shaped [n]CPPAs show an odd–even difference. In addition, the HOMOs of the [3]CPPA, [5]CPPA, [7]CPPA and [9]CPPA are doubly degenerate. 相似文献
108.
An analytical and numerical study of peristaltic transport of a Johnson-Segalman fluid in an endoscope
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In the present study, we discuss the peristaltic flow of a Johnson-Segalman fluid in an endoscope. Perturbation, homotopy, and numerical solutions are found for the non-linear differential equation. The comparative study is also made to check the validity of the solutions. The expressions for pressure rise frictional forces, pressure gradient, and stream lines are presented to interpret the behavior of various physical quantities of the Johnson-Segalman fluid. 相似文献
109.
In the presence of spin and pseudospin (p-spin) symmetries, the approximate analytical bound states of the Dirac equation for scalar-vector-tensor Hulth6n potentials are obtained with any arbitrary spin-orbit coupling number using the Pekeris approximation. The Hulth6n tensor interaction is studied instead of the commonly used Coulomb or linear terms. The generalized parametric Nikiforov-Uvarov (NU) method is used to obtain energy eigenvalues and corresponding wave functions in their closed forms. It is shown that tensor interaction removes degeneracy between spin and p-spin doublets. Some numerical results are also given. 相似文献
110.
Akbar B. Aliev Anar A. Kazimov Vusala F. Guliyeva 《Mathematical Methods in the Applied Sciences》2013,36(9):1133-1144
In this paper, we investigate the Cauchy problem for a class of the system of semilinear hyperbolic equations with damping. With the use of the Lp → Lq type estimation for the corresponding linear problem and the method of comparison of functional, the existence and nonexistence criteria of global solutions are found. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献