Synthesis,Crystal Structure,and Characterization of Na7Cu4(AsO4)5

Abstract

Sodium copper (II) arsenate Na₇Cu₄(AsO₄)₅ has been grown by conventional high-temperature, solid-state methods in molten-salt media. It was characterized by single crystal X-ray diffraction (XRD), thermal analysis (DTA–TGA), scanning electron microscopy (SEM), semiquantitative energy dispersive spectroscopy analysis (EDS), and vibrational spectroscopy. Na₇Cu₄(AsO₄)₅ exhibits a three-dimensional framework built up of CuO₅, CuO₄, and AsO₄ polyhedra, with intersecting channels in which the Na⁺ cations are located. The three-dimensional cohesion of the framework results from Cu–O–As bridges. CuO₅ and CuO₄ polyhedra are elongated due to the Jahn–Teller effect, whereas AsO₄ tetrahedra are almost regular. This new structural model is validated by the charge distribution (CD) analysis. The infrared and Raman spectra confirmed the presence of AsO₄ tetrahedra.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional tables and figures.]     

Biochemical study for the effect of henna (Lawsonia inermis) on Escherichia coli

Leaf samples of Lawsonia inermis (Li) were examined for their antimicrobial potential. Broth extracts in different concentrations were prepared and bioassayed in vitro for the growth of Escherichia coli. The growth of E. coli pathogen was inhibited to various degrees by increasing the concentration of the herbal powder. In addition to the observed alterations which were detected electrophoretically in the protein pattern, were activities of the amylase enzyme and glycoprotein fractions. The protein pattern has one common band of Rf 0.47 and two characteristic bands of Rf 0.36 and Rf 0.42 for E. coli sample. The quantitative mutation was observed in the bacteria with different concentrations of L. inermis compared with the control. Some types of proteins in E. coli completely disappeared upon being S.I affected. The amylase pattern showed one common band with Rf 0.037 and two characteristic bands with Rf 0.18 and Rf 0.37 for E. coli sample. The obvious quantitative mutation observed in bacteria with different concentrations of L. inermis compared with E. coli. The glycoprotein pattern recorded one common band at R₁ with Rf 0.94 for E. coli sample and bacteria inoculated with different concentrations of L. inermis. These results confirmed the antibacterial activity of henna leaves and supported the traditional use of the plant in therapy of bacterial infections and disturbances that occurred at the biochemical level. The broth extract of the L. inermis leaves showed obvious antibacterial activity against E. coli.     

Synthesis and in vitro anticancer activity of some novel tetrahydroquinoline derivatives bearing pyrazol and hydrazide moiety

A new series of tetrahydroquinoline derivatives having pyrazol and hydrazide moieties were synthesized for the purpose of anticancer cell line evaluation. Syntheses of these compounds were firstly achieved by one pot four reactions. The reaction of 3-amino-tetrahydro-1H-pyrazolo [3,4-b]quinolin with aldehydes, indoline-2,3-dione derivatives to give 9a-c , 11a-c , and 13a,b , respectively. In similar manner for biological comparison, the reactions of compound 5 with the same aldehydes and indoline-2,3-dione derivatives to give 19a-c and 20a-c . The newly synthesized compounds were examined in vitro for their cytotoxic activity against HepG-2 and A549 cancer cells. The compounds 11a-c and 20a-c showed promising activity as anticancer agents against HepG-2 and A549 cancer cells.     

A contribution to the evaluation of REE in an Egyptian phosphate deposit

Results are presented of ICP-AES determinations of 13 rare earth elements (REE), Sc and Y in 47 core samples of 10 bore holes in the phosphate deposit of the Abu-Tartur area, Western Desert, Egypt. The complete dissolution of the samples was achieved by digestion with HF/HNO₃/HCl in a closed PTFE decomposition vessel. Such analytical lines were selected that showed no spectral interferences from the major constituents of the phosphate samples or from other REE in the samples. The precision for the determination of the individual elements for the whole procedure ranges from 0.8% to 4.0%. Also, smooth normalized chondrite and shale patterns were obtained. The results revealed that the total REE content in the investigated samples was between 0.8 and 2 mg/g, which is remarkably high when compared with many phosphate deposits in other parts of the world. The results also showed that the concentrations of individual REE as well as their total concentrations in the samples follow their P₂O₅ content, indicating that the REE may be accumulated within the phosphate fraction of the phosphate bearing sediments.Presented at the Rare Earth Minerals Conference, London (UK), April 1 and 2 (1993)     

DFT study of hydrogen storage in Pd-decorated C60 fullerene

Hydrogen storage reactions on Pd-doped C₆₀ fullerene are investigated by using the state-of-the-art density functional theory calculations. The Pd atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to four hydrogen molecules with average adsorption energies of 0.61, 0.45, 0.32, and 0.21 eV per hydrogen molecule. With no metal clustering, the system gravimetric capacities are expected to be as large as 5.8 wt%. While the desorption activation barriers of the complexes nH₂ + Pd–C₆₀ with n = 1 are outside the department of energy (DOE) domain (?0.2 to ?0.6 eV), the desorption activation barriers of the complexes nH₂ + Pd–C₆₀ with n = 2–4 are inside this domain. While the interaction of 1H₂ with Pd + C₆₀ is irreversible at 459 K, the interaction of 2H₂ with Pd + C₆₀ is reversible at 529 K. The hydrogen storage of the irreversible 1H₂ + Pd–C₆₀ and reversible 2H₂ + Pd–C₆₀ interactions are characterised in terms of densities of states, infrared, Raman, and proton magnetic resonance spectra, electrophilicity, and statistical thermodynamic stability.     

Density functional theory study of hydrogen storage on Ni-doped C59X (X = B,N) heterofullerene

ABSTRACT

Hydrogen storage reactions on Ni ? C₅₉X(X = B, N) heterofullerene are investigated by using the state-of-the-art density functional theory calculations. The Ni atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to five hydrogen molecules with average adsorption energies of (?0.94, ?0.48, ?0.33, ?0.25 and ?0.20 eV) per hydrogen molecule for Ni ? C₅₉B, while (?1.20, ?0.60, ?0.41, ?0.28 and ?0.23 eV) per hydrogen molecule for Ni ? C₅₉N. With no metal clustering, the system gravimetric capacities are expected to be as large as 10.87 and 10.85 wt % for 5H₂NiC₅₉B?and 5H₂NiC₅₉N, respectively. While the desorption activation barriers of the complexes 1H₂ + C₅₉X?(X = B, N)?are outside the Department of Energy domain (?0.2 to ?0.6 eV), the desorption activation barriers of the complexes nH₂ + C₅₉X(X = B, N)(n = 2 ? 5) are inside this domain. The hydrogen storage of the irreversible 1H₂ + NiC₅₉X?(X = B, N) and reversible 2H₂ + NiC₅₉X?(X = B, N) interactions is characterised in terms of density of states and projected densities of states, pairwise and non-pairwise additivity, infrared, Raman, electrophilicity and molecular electrostatic potentials.     

Sur la magnétohydrodynamique anisotrope relativiste

Summary This paper is concerned with the relativistic phenomenological theory of anisotropic magnetohydrodynamics. An anisotropic fluid scheme is defined and studied. The main system of anisotropic magnetohydroldynamics is deduced. This system may describe a collisionless anisotropic plasma embedded in a strong magnetic field. The main system is shown to yield to three types of waves as in isotropic (perfect) magnetohydrodynamics: the entropic waves, the magnetosonic waves and the Alfven waves. For the rays associated respectively to the magnetosonic and Alfven waves the fundamental property concerning the propagation of infinitesimal discontinuities of variables is established. The conditions under which the velocities of propagation of magnetosonic and Alfven waves are real are derived: these conditions imply as in the classical theory the absence of fire hose and mirror instabilities in the fluid. The study of wave cones allows, on the one hand to point out some particularities of the propagation of waves in anisotropic magnetohydrodynamics, and on the other hand to clear up the hyperbolicity character of differential operators associated to various waves.

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Entrata in Redazione il 23 aprile 1975.     

Theoretical characterization of axial deformation effects on hydrogen storage of Ti decorated armchair (5,5) SWCNT

Theoretical calculations have been performed in the framework of density functional theory to characterize the effect of axial deformation on hydrogen storage of Ti decorated armchair (5,5) SWCNT. The theoretical characterization has been carried out in terms of H₂ adsorption energies that are lying in the desirable energy window (?0.2 to ?0.6?eV) recommended by DOE, as well as a variety of physicochemical properties. A remarkable and significant change in H₂ adsorption energy is observed under the effect of only (1%) axial strain. Axial relaxation leads to H₂ adsorption energies within the recommended energy range for hydrogen storage, in contrast to axial compression. Simultaneous weakening of π and σ interactions, due to the effect of axial relaxation and loss of spatial orbital overlap, is in favor of hydrogen adsorption in the recommended energy range, and dominates the effect of charge transfer from Ti 3d to C 2p of the SWCNT. The calculated pairwise and non pairwise additive components confirm that the role of the SWCNT is not restricted to supporting the metal. Polarizability and hperpolarizabilty calculations as well as spectral analysis characterize the relaxed structure (Z?=?1.02), for which H₂ adsorption energy (?0.34?eV) is in the recommended energy range for hydrogen storage, to be energetically more preferable than the compressed structure (Z?=?0.99). The results offer a way to control and characterize the hydrogenation process of metal functionalized SWCNTs by strain loading.     

Simultaneous impacts of MHD and variable wall temperature on transient mixed Casson nanofluid flow in the stagnation point of rotating sphere

A numerical analysis is provided to scrutinize time-dependent magnetohydrodynamics(MHD) free and forced convection of an electrically conducting non-Newtonian Casson nanofluid flow in the forward stagnation point region of an impulsively rotating sphere with variable wall temperature. A single-phase flow of nanofluid model is reflected with a number of experimental formulae for both effective viscosity and thermal conductivity of nanofluid. Exceedingly nonlinear governing partial differential equations(PDEs)subject to their compatible boundary conditions are mutated into a system of nonlinear ordinary differential equations(ODEs). The derived nonlinear system is solved numerically with implementation of an implicit finite difference procedure merging with a technique of quasi-linearization. The controlled parameter impacts are clarified by a parametric study of the entire flow regime. It is depicted that from all the exhibited nanoparticles,Cu possesses the best convection. The surface heat transfer and surface shear stresses in the x-and z-directions are boosted with maximizing the values of nanoparticle solid volume fraction ? and rotation λ. Besides, as both the surface temperature exponent n and the Casson parameter γ upgrade, an enhancement of the Nusselt number is given.