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421.
Trabelsi S Nasr S Bahri M Bellissent-Funel MC 《The journal of physical chemistry. B》2006,110(49):25021-25025
A structural investigation of fully deuterated liquid N-methylacetmide (NMAd7) is performed at 308 K and atmospheric pressure by using neutron diffraction together with density-functional theory (DFT). The analysis of experimental data yields the total structure factor SM(Q), the molecular form factor F1(Q), and the distinct pair correlation function gL(r). The DFT calculations are performed to study the relative stability of the two possible isomers (trans and cis) and to examine some possible clusters recently published that may describe the intermolecular arrangement in the liquid state. Neutron measurements can be interpreted in terms of trans linear trimer (T1) and cis cyclic trimer (T2) where the total number of hydrogen bonds is respectively equal to two and three. The theoretical structure factors obtained on the basis of intermolecular arrangements agree fairly well with the experimental one beyond Q = 2 A-1. All through the study, a comparison is made with complementary X-ray results. 相似文献
422.
In Corollary 12(ii) and Theorem 13(v) of [1] we omitted the hypothesis dim $ \mathfrak{z}\leq 1 $ . Moreover, in some places the symbol $ \mathbb{K} $ must be replaced by the symbol $ {{\mathbb{K}}^{\times }} $ . 相似文献
423.
H. Grissa F. Askri M. Ben Salah S. Ben Nasrallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(3):494-513
In this paper, the control volume finite element method (CVFEM) is applied for the first time to solve nonaxisymmetric radiative transfer in inhomogeneous, emitting, absorbing and anisotropic scattering cylindrical media. Mathematical formulations as well as numerical implementation are given and the final discretized equations are based on similar meshes used for convective and conductive heat transfer in computational fluid dynamic analysis. In order to test the efficiency of the developed method, four nonaxisymmetric problems have been examined. Also, the grid dependence and the false scattering of the CVFEM are investigated and compared with the finite volume method and the discrete ordinates interpolation method. 相似文献
424.
Dounia zed Mezdour Mohamed Tabellout Salah Sahli Kateryna Fatyeyeva 《Macromolecular Symposia》2010,290(1):15-24
Summary: Volume conducting PA-12 based composites powders were chemically prepared by in situ polymerization and aniline doping at room temperature. These kinds of polyamide / PANI composites were investigated regarding their electrical properties. Their ac and dc electrical properties measured in the frequency range of 10−2–107 Hz are reported and the frequency dependence of electrical conductivity was investigated as a function of PANI concentration leading to the determination of the conductivity. The experimental conductivity was found to increase continuously with PANI content and explained by percolation theory with a relatively low percolation threshold of about 0.4 wt.%. The dielectric behavior of various PANI polymer composites has been characterized by the critical frequency ωc (denoting the crossover from the dc plateau of the conductivity to its frequency dependent ac behaviour). Modelling the conductivity behavior versus volume fraction using Slupkowski approach has revealed that the considered parameters are not sufficient to describe the electrical conductivity behavior. 相似文献
425.
M. Loukil A. Kabadou I. Svoboda A. Ben Salah H. Fuess 《Journal of chemical crystallography》2008,38(2):85-91
Abstract Single crystal diffraction and differential scanning calorimetry DSC techniques have been used to investigate the different
phases of (NH4)4HgBr6, tetrammonium mercury hexabromide, from room temperature to 120 K. Two anomalies in thermal behaviour were detected for this
compound at 190 and 268 K, by DSC experiment. X-ray diffraction measurements confirm these anomalies. At room temperature
the structure is tetragonal P4/mnc (No. 128) with lattice parameters a = b = 9.25560(8) ?; c = 8.8657(11) ?; V = 759.49(9) ?3 and Z = 2. At T = 250 K the structure is orthorhombic Pnnm with lattice parameters a = 8.8436(8) ?; b = 9.2191(8) ?; c = 9.2232(7) ?;
V = 751.97(11) ?3 and Z = 2. Below approximately 200 K the structure is monoclinic P21/n (No. 14) with: a = 8.8080(9) ?; b = 9.1608(8) ?; c = 9.1498(8) ?; β = 90.230(7)°; V = 738.28(12) ?3 and Z = 2 (T = 120 K). The structure of (NH4)4HgBr6 consists of isolated HgBr6-octahedra in the whole temperature range which are slightly compressed in c-direction. The ammonium groups are located between
the octahedra ensuring the stability of the structure by hydrogen bonding contacts: N–H···Br. The structural phase transformations
are described by a rotation of the [HgBr6]2− octahedra around the c-axis, and this behaviour is attributed to an orientational disorder of ammonium groups.
Index abstract Structural analysis of the phase transitions of (NH4)4HgBr6; M. Loukil, A. Kabadou, I. Svoboda, A. Ben Salah and H. Fuess; The phase transformations in (NH4)4HgBr6 are explained by large rotation of [HgBr6]2− octahedra around the c-axis.
相似文献
426.
N. Ayyanar Ahmed E. Khalil Mohamed Farhat O. Hameed G. Thavasi Raja Salah S. A. Obayya 《Optical and Quantum Electronics》2018,50(12):453
A Hemoglobin (Hb) biosensor based on dual-core photonic crystal fiber is proposed and analyzed. In this paper, the effective refractive index dependency on the Hb concentration within a blood sample is utilized in obtaining the transmission spectrum variation. The results are calculated using full vectorial finite element method. Through this study, the effect of the structure geometrical parameters on the sensor performance is optimized to maximize the sensor sensitivity. The numerical results show a sensitivity of 8.013 nm/g/dL for the X-polarized mode at 3.7 cm fiber length and 7.68 nm/g/dL for the Y-polarized mode at 3.2 cm fiber length of the proposed sensor. 相似文献
427.
Salah Shahine 《Mikrochimica acta》1980,73(1-2):123-127
Summary A new titrimetric method for the microdetermination of ascorbic acid has been developed. It is based on the oxidation of ascorbic acid to dehydroascorbic acid with copper(II) in presence of ammonium thiocyanate; potassium iodide and starch are used as indicator. The method is especially suitable for dilute solutions (<0.05N) and can be used over the pH range 1–7. Glucose, fructose, aspirin, caffeine, rutin and calcium gluconate do not interfere, and neither do citrate, oxalate and tartrate if the titration is done at pH 1-2. Bisulphite can be masked with acetone, but novalgin must be absent. The method is simple, sensitive and accurate.
Mikrotitration von Askorbinsäure mit Kupfer
Zusammenfassung Eine neue maßanalytische Methode zur Mikrobestimmung von Askorbinsäure wurde ausgearbeitet. Sie beruht auf deren Oxydation zu Dehydroaskorbinsäure mit Kupfer(II) in Gegenwart von Ammoniumrhodanid; Kaliumjodid und Stärke dienen als Indikator. Das Verfahren eignet sich besonders für verdünnte Lösungen (<0,05N) und ist im pH-Gebiet 1-7 anwendbar. Glukose, Fructose, Aspirin, Coffein, Rutin und Calciumglukonat stören nicht, ebenso wenig Zitrat, Oxalat und Tartrat, soferne bei pH 1-2 titriert wird. Bisulfit kann mit Aceton maskiert werden, aber Novalgin darf nicht anwesend sein. Das Verfahren ist einfach, empfindlich und genau.相似文献
428.
A.?S.-F.?Obada H.?H.?Salah M.?A.?Darwish E.?M.?KhalilEmail author 《International Journal of Theoretical Physics》2005,44(9):1347-1364
Generalized trio coherent states are made by superposing a number of trio coherent states. They possess inherent nonclassical
properties such as sub-Poissonian distribution and violation of Cauchy-Schwarz inequalities. Their phase distribution in the
framework of the Pegg and Barnett theory is discussed. We study the interaction of the radiation field prepared in a generalized
trio coherent state with an atom in a superposition coherent state in the rotating wave approximation. We investigate the
time dependence of the sub-Poissonian distribution and the violation of Cauchy-Schwarz inequalities for such a system. General
conclusions reached are illustrated by numerical results. 相似文献
429.
430.
Tejada-Rosales EM Rodríguez-Carvajal J Casañ-Pastor N Alemany P Ruiz E El-Fallah MS Alvarez S Gómez-Romero P 《Inorganic chemistry》2002,41(25):6604-6613
Ag(2)Cu(2)O(3) is the first known silver copper oxide. It was prepared by coprecipitation at room temperature and ambient pressure and shows an increased thermal stability compared with silver oxides. The crystal structure (tetragonal, a = 5.8862(2) A, c = 10.6892(4) A, Z = 4, I4(1)/amd) was refined from neutron and X-ray powder diffraction data, and it is related to that of the mineral paramelaconite (Cu(4)O(3)). In addition to a thorough characterization (chemical and TG analyses, XPS, crystal structure, and electrochemical, magnetic, and transport properties), we have carried out band structure calculations [extended Hückel tight binding (EHTB) and spin polarized density functional (DFT) band calculations] for the title silver copper oxide and for the related paramelaconite structure (Cu(II)-Cu(I) mixed-valence system) with special incidence into the magnetic behavior and coupling constants in these magnetically novel 3-D compounds. This new oxide represents an important precedent in solid state inorganic chemistry but also has potential interest concerning its magnetic, electrochemical, and catalytic properties. 相似文献