Natural convection of non-Newtonian fluids in a horizontal porous layer

Heat and Mass Transfer - The buoyancy-induced flows of non-Newtonian fluids in a horizontal fluid saturated porous layer is studied analytically and numerically using the power-law model to...     

Chemometric resolution of ATR-IR spectra data for polycondensation reaction of bis(hydroxyethylterephthalate) with a combination of self-modeling curve resolution (SMCR) and local rank analysis

Self-modeling curve resolution (SMCR) methods, simple-to-use interactive self-modeling mixture analysis (SIMPLISMA) and alternating least squares (ALS) were used to calculate pure concentration profiles and pure spectra for the two-way spectral data collected during the on-line polycondensation reaction of bis(hydroxyethylterephthalate) with an ATR-FT-IR spectrometer. In order to improve the resolution results, SIMPLISMA was combined with local rank analysis method, fixed size moving window evolving factor analysis (FSMWEFA) to search for selective regions of various components and then look for the purest wavenumber variables in the selective regions. Such combination allows more accurate determination of the number of chemical components in the reaction system and the calculations of more accurate concentration profiles and spectra.     

Synthesis and Structures of [Mo12E16(PEt3)10] (E = S,Se)

Dodecanuclcar cluster complexes [Mo₁₂S₁₆(PEt₃)₁₀] 1 and [Mo₁₂Se₁₆(PEt₃)₁₀] 2 have been prepared by the reactions of [Mo₆S₈(PEt₃)₆] with sulfur or [Mo₆Se₈(PEt₃)₆] with Cp₂TiSe₅, respectively, in toluene at refluxing temperature. The structures have been determined at 173 K by X-ray crystallography. The compound 1 ·3CHCl₃ crystallizes in the triclinic space group $ {\rm P}\bar 1 $, with a = 14.859(5) Å, b = 15.868(4) Å, c = 14.200(7) Å, α = 100.58(3)°, β = 117.58(3)°, γ = 79.53(2)°, V = 2899(1) ų, and Z = 1. Full-matrix least-squares refinement using 9016 observed reflections (I_o > 2σ(I_o)) gave R = 0.056, and R_w = 0.045. The data for 2 ·2CHCl₃ are: triclinic, $ {\rm P}\bar 1 $, a = 15.737(4) Å, b = 18.763(9) Å, c = 13.062(4) Å, α = 102.45(3)°, β = 128.54(2)°, γ = 69.49(3)°, V = 2825 ų, Z = 1, R = 0.096, and R_w = 0.120 for 5922 reflections (I_o > 2σ(I_o)). The cluster complexes 1 and 2 have two octahedral molybdenum cluster units linked by the rhomboidal intercluster Mo₂(μ₄-E)₂ bonding. The intercluster Mo—Mo distances in 1 are 3.419 Å and 2 3.551 Å. The cyclic voltammetry of 1 and 2 shows two oxidation and two reduction steps separated as large as 380–490 mV. The UV-Vis spectra of the dodecanuclear cluster complexes 1 and 2 have an extra weak band at around 744 nm which is absent in the starting octahedral cluster complexes.     

Positron Energy Levels in Cd-Based Semiconductors

Using the full potential linearized augmented plane wave FP-LAPW method within local density ap-proximation LDA, we have studied positron diffusion and surface emission in Cd-based semiconductors. This requires the calculation of electron and positron band structures. In the absence of experimental and theoretical data for CdX (X=S,Se,Te) we have treated the Si, which has been studied by several authors, as a test case. Predictive results on positron effective masses, deformation potentials, positron work functions, diffusion constants and positron mobilities are presented for CdX (X=S, Se, Te). Our calculated data for Si are compared with experimental and recent theoretical results.     

The dissociation of the 2Π fluoroethylene anions

Dissociative electron attachment spectroscopy is employed to study formation of stable negative ion fragments in the fluoroethylenes. It is found that in each case the energy of the first resonance leading to F^? and other stable negative ion fragments coincides with the energy of the temporary Π anions. Tetrafluoroethylene gives fragments by cleavage of the double bond.     

Helicity redistribution during relaxation of astrophysical plasmas

We present the first 3D numerical MHD simulations that show that Taylor's relaxation conjecture is not satisfied in some MHD evolution of magnetic configurations encountered in solar physics. We show that magnetic helicity can be slowly injected through the boundary into a magnetic configuration which then evolves into a MHD disruption, with the formation in finite time of a current sheet through which reconnection occurs, leading to a release of magnetic energy. While helicity is well conserved during the process, it is shown that the relaxed state is far from the constant- alpha linear force-free field that would be predicted by Taylor's conjecture.     

Novel Basic Isoflavones as Inhibitors of Bone Resorption

A number of aminoalkoxy analogues of ipriflavone (=7‐(1‐methylethoxy)isoflavone) were prepared and examined for their capacity to inhibit bone resorption induced by bovine parathyroid hormone fragment 1 – 34. Good‐to‐high activities were found for 7‐(aminoalkoxy)isoflavone analogues. Their activity was influenced by a number of structural features, among which the length of the basic side chain, the basicity of the amino group, and the nature and position of substituents on the 3‐phenyl ring. 4′‐(Aminoalkoxy)ipriflavone derivatives were less active.     

Réactivité de l’acide déhydroacétique hydrogené en c5-c6 : obtention des pyrano-1,5-benzodiazépines différemment substituées et de la structure enaminone

A number of 1,5-benzodiazepines derivatives 4 were obtained via the interaction of dehydroacetic acid hydrogenated at C₅-C₆, orthophenylenediamines and aromatic aldehydes. The interpretation of the results is enriched by a study of the electronic effects of the DHA hydrogenated at C₅-C₆. Accordingly, it leads us to obtain the original structure cynnamoyle 5.     

Structural,Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method: Effect of Precursor Concentration

Transparent zinc oxide(ZnO) thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations(0.3-1.2 M) using zinc acetate dehydrate [Zn(CH_3COO)_2·2H_2O] as precursor and isopropanol and monoethanolamine(MEA) as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.