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71.
Physics of the Solid State - We have investigated the magnetic properties of Mn-doped LiZnAs half-Heusler compound using density functional simulations within the gradient generalized approximation... 相似文献
72.
We investigate the temperature effect on the structural and dynamical properties (translation, rotation) of an urea/water system at 0.20 mole fraction of urea. We report the radial distribution functions of like and unlike molecules and conclude that, even at large distances, these molecules are spatially correlated (with respect to their centers of mass). This behavior is interpreted as an indication that urea molecules are not uniformly distributed at a microscopic level. However, the orientational distribution shows that, at long distances, the urea molecules are not orientationally correlated. A strong correlation between urea molecules is observed within the first-shells of neighboring molecules. In view of these results, it is postulated that urea behaves slightly like a nonpolar molecule. The dynamical properties were analyzed using the velocity (translation) and angular velocity (rotation) time autocorrelation functions, as well as their Fourier transforms. The results indicate a significant hydrogen bonding between urea and other molecules in the solution. 相似文献
73.
M. Ramezanizadeh M. Taeibi-Rahni M. H. Saidi 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(11):835-847
In this work, hydrodynamic effects of multiple squared cross-section cold jets inclined normally into a hot cross flow were
computationally simulated using large eddy simulation (LES) approach. The finite volume method and the SIMPLE algorithm on
a multi-block non-uniform staggered grid were applied. The jet into cross flow velocity ratio and the jet Reynolds number
were 0.5 and 4,700, respectively. Simulations were performed for three different jets into cross flow temperature ratios,
namely, 2, 1, and 0.5, corresponding to density ratios of 0.5, 1, and 2. The experimental and numerical results of Ajersch
et al. (J. Turbomachinery 119(2), 330–342, 1997) at unit density ratio were used for validation purposes. The density ratio effects on the flow characteristics
were investigated. It was shown that the density ratio has significant effects on the hydrodynamics of the jet into cross
flow problems and even though the flow Mach number may be low, its effects due to temperature differences between the jet
and the cross flow cannot be easily ignored. 相似文献
74.
Ash's functions N σ ,k count the number of k ‐equivalence classes of σ ‐structures of size n . Some conditions on their asymptotic behavior imply the long standing spectrum conjecture. We present a new condition which is equivalent to this conjecture and we discriminate some easy and difficult particular cases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
75.
76.
Alireza Jahangiri Majid Saidi Farhad Salimi Abolfazl Mohammadi 《Research on Chemical Intermediates》2018,44(3):1755-1773
In this study, nano catalyst LaNiO3 with perovskite structure was synthesized using the citrate sol–gel method in the combined methane reforming with CO2 and O2 (CRM). The effects of increasing the surface area of the LaNiO3 perovskite on the catalytic activity were investigated by changing the method of preparing and creating holes in the surface of the samples. Physical and chemical properties of the samples, before and after the reactor test, were determined through ICP, AA, XRD, TGA, TPR, BET, SEM, EDX and TEM techniques. The results of XRD, ICP, AA, SEM, EDX and TEM tests indicated that the citrate sol–gel method is a good way to prepare a homogeneous perovskite LaNiO3 sample on a scale of nanometers. The results of the TPR test showed using etching in the citrate sol–gel method can produce samples with high stability. The BET results indicated that the surface area of the LaNiO3 sample tripled with the method suggested in this paper. Changes in preparation method lead to induction time decreasing and temperature increasing. Use of etching in the citrate sol gel method had no significant effect in the results of activity tests versus time reaction at a temperature of 800 °C. TGA curves revealed no production of coke over the process for the produced samples. 相似文献
77.
Khaoulani Idrissi Abdallah Saadi Mohamed Rafiq Mohamed Guelzim Abdelhalim 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):i43-i45
The structure of the title compound, (NH4)2[Mg(H2O)6]3(HPO3)4, consists of [Mg(H2O)6]2+ and (NH4)+ cations and (HPO3)2− anions held together by an intricate network of hydrogen bonds involving all H atoms except for one linked directly to a P atom. The Mg2+ cations are octahedrally coordinated by six water molecules. One of the Mg atoms is located on a site with 2/m symmetry, whereas the other Mg atom and the P and N atoms occupy sites with m symmetry. 相似文献
78.
Several 2,2,2-trifluoroacetimidoyl chlorides have been prepared in a one-pot stage from primary aromatic amines and trifluoroacetic acid. The reactions were carried out with different primary aromatic amines which they contain additional functional groups and good yield were obtained. 相似文献
79.
The liquid-solid phase diagram of the binary systems AlPO4?M3PO4(M=Li, Na, K) have been established. The additional compounds Na3Al(PO4)2, Na3Al2(PO4)3 and K3Al2(PO4)3 have been found again. A new compound K3Al(PO4)2 is observed. The melting point of Na3PO4 is 1545°C and K3PO4 does not melt up to 1700°C. 相似文献
80.
Malika Lahiani-Skiba Yannick Boulet Ibrahima Youm Fréderic Bounoure Philippe Vérité Philippe Arnaud Mohamed Skiba 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):211-217
The aim of the study was to evaluate if the complexation of a hydrophilic molecule by cyclodextrins is possible. Cyclodextrins
(CDs) are hydrophilic cone shaped molecules, which are used as vehicles able to include organic molecules. Because of the
presence of hydroxy groups (OH) outside of the molecule, cyclodextrins are not predisposed to include hydrophilic drugs. They
are therefore used to improve the solubility of poor water-soluble molecules. In order to evaluate if the complexation of
a hydrophilic molecule by cyclodextrins is possible, lyophilized complexes of cysteamine hydrochloride with α-cyclodextrins
(α-CD) have been realized. Six analytical techniques (High performance Liquid Chromatography coupled to UV detection, Thin-Layer
Chromatography, Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Mass Spectrometry
(SM) and Proton Nuclear Magnetic Resonance (NMR-NOESY spectra)) were used in order to characterize the interaction between
the drug and the α-CD. The realization of complex between a cyclodextrin and a water-soluble drug seems feasible. In the case
of a hydrophilic molecule, the complexation is not obtained by inclusion of the drug in the cyclodextrin, but by binding to
the outside of the cone. This “external complexation” is however sufficient to improve some features of the molecule, such
as organoleptic features, and to modifiy measurable parameters (FT-IR, DSC, SM and NMR-NOESY spectra). 相似文献