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101.
The area method was proposed in 1992 to calculate binary and ternary 2-phase equilibria. In its integral form, the method provides both the necessary and sufficient conditions required for the determination of the global minimum reduced Gibbs energy of mixing (Φ). The method has since been applied to the calculation of both pure component and ternary multiphase equilibria in a differential form. However, the extension of the original (2 point) integral area method to the direct calculation of both binary and ternary multiphase equilibria has not been completed. Direct 3 point and modified 2 point search methods have therefore been developed here and used to estimate the phase compositions of a representative binary vapour-liquid-liquid system. The 2 point area method principle has been extended and applied to the calculation of ternary multiphase equilibria using a net volume approach. However, this volume method was found to fail due to an underlying inconsistency in the bounding of the integrated Φ surface by the trial 3-phase region. A new method is proposed that overcomes this problem by minimising the area of intersection between a tangent plane and the Φ surface. This new method has successfully calculated the 3-phase compositions of two simple test systems from a variety of initial mixture starting points. 相似文献
102.
Suchada Chantrapromma Anwar Usman Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m531-m533
In the title compound [systematic name: triaqua(1,4,7,10,13,16‐hexaoxacyclooctadecane‐κ6O)(2‐nitrophenolato‐κO)barium(II)–aqua(1,4,7,10,13,16‐hexaoxacyclooctadecane‐κ6O)‐ bis(2‐nitrophenolato‐κ2O,O′)barium(II)–2‐nitrophenolate (1/1/1)], [Ba(C12H24O6)(C6H4NO3)(H2O)3][Ba(C12H24O6)(C6H4NO3)2(H2O)](C6H4NO3), the two BaII atoms encapsulated by the 18‐crown‐6 rings have different coordinations. Although both BaII atoms are coordinated to the six O atoms of the crowns, in the neutral moiety, the BaII atom is coordinated to one terminal O atom from a water molecule, two phenolate O atoms and two nitro‐group O atoms, while in the cationic moiety, the BaII atom is coordinated to three terminal O atoms from water molecules and one phenolate O atom. Both the crowns are eclipsed and translated along the b direction. In the asymmetric unit, the three components are interconnected by four O—H?O interactions. The packing is stabilized by two intermolecular C—H?O interactions and by one O—H?O interaction. 相似文献
103.
Cécile DeWitt-Morette Stephen G. Low Lawrence S. Schulman Anwar Y. Shiekh 《Foundations of Physics》1986,16(4):311-349
The wedge problem, that is, the propagation of radiation or particles in the presence of a wedge, is examined in different contexts. Generally, the paper follows the historical order from Sommerfeld's early work to recent stochastic results—hindsights and new results being woven in as appropriate. In each context, identifying the relevant mathematical problem has been the key to the solution. Thus each section can be given both a physics and a mathematics title: Section 2: diffraction by reflecting wedge; boundary value problem of differential equations; solutions defined on mutiply connected spaces. Section 3: geometrical theory of diffraction; identificiation of function spaces. Section 4: path integral solutions; path integration on multiply connected spaces; asymptotics on the boundaries of function spaces. Section 5: probing the shape of the wedge and the roughness of its surface; stochastic calculus. Several propagators and Green functions are given explicitly, some old ones and some new ones. They include the knife-edge propagator for Dirichlet and Neumann boundary conditions, the absorbing knife edge propagator, the wedge propagators, the propagator for a free particle on a -sheeted Riemann surface, the Dirichlet and the Neumann wedge Green function.Supported in part by NSF grant PHY84-04931.Supported in part by SERC grant GR/D 15911.Supported in part by a NSERC (Canada) Fellowship.Supported in part by SERC grant B/83301669. 相似文献
104.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):o59-o62
In the syn‐ and anticlinal isomers of the title compound, C22H18N2O6, the indole moiety is not completely planar, with the pyrrolidine ring being distorted very slightly towards a conformation intermediate between half‐chair and envelope. The molecular and packing structures in the crystals of these isomers are stabilized by C—H?O interactions. 相似文献
105.
Bromide was determined at nanogram levels by introducing the sample with excess aluminum into a graphite furnace and measuring the laser-excited molecular fluorescence of aluminum bromide. Experimental parameters including excitation and fluorescence wavelengths, thermal conditions and aluminum concentration were optimized. Effects of concomitant ions and of barium hydroxide concentration, as a matrix modifier, have also been checked. The analytical reliability of the described procedure was checked by determining the bromide content in a standard reference material. 相似文献
106.
Reduction of acyl cyanides with zinc in acetic acid in the presence of excess acetic anhydride leads to N-acetyl-α-aminoketones in good yields. An efficient three-step synthesis of 5-aminolevulinic acid by this method is described. 相似文献
107.
108.
Mohammad Wasim Muhammad Daud Mohammad Arif Rameez ul-Islam Sajid Iqbal Yasir Anwar 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):653-659
In the under developed countries, the people of far-flung rural areas still depend to a large extent upon herbal medicines.
At the foundation of usage of herbal medicine is the experience of thousands of years. The present paper deals with the characterisation
of exotic fruits for essential and toxic elements. The samples include Morus nigra, Morus alba, Salvadora persica and Carissa opaca (from low and high altitude). Two standardizations of neutron activation analysis, that is, semi-absolute k
0-instrumental neutron activation analysis (k
0-INAA) and epithermal neutron activation analysis (ENAA) were employed for the quantification of elements. The analysis methodologies
were validated by analyzing the IAEA-336 (lichen) and NIST-SRM-1572 (citrus leaves). Sixteen elements including Br, Ca, Cl,
Co, Cr, Fe, I, K, Mg, Mn, Na, Rb, Sb, Sc Sr, and Zn were determined in all samples. Daily intakes of various elements from
the samples were measured and compared with the dietary reference intakes. Additionally, principal component analysis was
performed to extract information regarding samples and elements. 相似文献
109.
Russian Journal of General Chemistry - Synthesis of new compounds combining benzimidazole with 1,3,4-oxadiazole functionalized by various alkyl and heterocyclic moieties is studied. The new hybrids... 相似文献
110.
In this paper, we study the static and dynamic snap-through of a shallow arch resting on a two-parameter elastic foundation under a point load moving at a constant speed. The deformation of the arch is expressed in Fourier series. We extend the previous works when the arch resting on a certain model of two-parameter elastic foundation. Each model of foundation has a different definition for the second foundation parameter, where the model is discussed in this paper is Pasternak model. For quasi-static analysis, it is noted that the first four modes in the expansion are sufficient to predict the response of the arch. Similarly, when the point load moves with a significant speed, we integrate the equation of motion numerically using the first modes in the expansion. 相似文献