Effect of sparse distribution pores in a Soret-driven ferro thermohaline convection

Thermoconvective instability in a multicomponent fluid has very wide applications in industrial, ionospheric and geothermal systems. More often, it is found that the thermal diffusivity and mass diffusivity interact with each other in fluid systems. But in a liquid system, the effect of heat transport on mass transport is pronounced. In a ferrofluid system which is a synthesized liquid, it is often found that more than one component co-exists in the fluid system contributing to interactive diffusion. In the present analysis, it is intended to study the Soret effect on multicomponent ferrofluid saturating a porous medium with large variation in permeabilities. Linear stability analysis is used. Normal mode technique is applied. The numerical results are presented for both stationary and oscillatory instabilities. It is found that stationary instability is preferred irrespective of values of permeability of pores.     

Hydrostatic pressure and temperature dependence of correlation energy in a spherical quantum dot

The combined effects of hydrostatic pressure and temperature on the ground state binding energy of two electrons in a GaAs spherical quantum dot have been studied by using a perturbation approach within the effective-mass approximation. Our results show that an increment in temperature results in a decrease of the correlation energy while an increment in the pressure for the same temperature increases the correlation energy at a particular dot size. In all cases, it is observed that there is a decrease in the correlation energy due to an increase in the dot size with a given temperature and pressure. The combined effects of hydrostatic pressure and temperature affect the correlation energies appreciably for narrower dots only. The correlation contributes 10%–30% to the binding energy. All the calculations have been carried out with finite barriers, and good agreement is obtained with the existing literature values.     

A pressure-based algorithm for multi-phase flow at all speeds

A new finite volume-based numerical algorithm for predicting incompressible and compressible multi-phase flow phenomena is presented. The technique is equally applicable in the subsonic, transonic, and supersonic regimes. The method is formulated on a non-orthogonal coordinate system in collocated primitive variables. Pressure is selected as a dependent variable in preference to density because changes in pressure are significant at all speeds as opposed to variations in density, which become very small at low Mach numbers. The pressure equation is derived from overall mass conservation. The performance of the new method is assessed by solving the following two-dimensional two-phase flow problems: (i) incompressible turbulent bubbly flow in a pipe, (ii) incompressible turbulent air–particle flow in a pipe, (iii) compressible dilute gas–solid flow over a flat plate, and (iv) compressible dusty flow in a converging diverging nozzle. Predictions are shown to be in excellent agreement with published numerical and/or experimental data.     

Gelatin–Chitosan composite capped gold nanoparticles: a matrix for the growth of hydroxyapatite

Growth of hydroxyapatite (HA) on gelatin–chitosan composite capped gold nanoparticles is presented for the first time by employing wet precipitation methods and we obtained good yields of HA. Fourier transform infrared spectroscopy (FTIR) spectrum has shown the characteristic bands of phosphate groups in the HA. Scanning electron microscopy (SEM) pictures have shown spherical nanoparticles with the size in the range of 70–250 nm, whereas ≥2–50 nm sized particles were visualized in high resolution transmission electron microscopy (HR-TEM). X-ray diffraction (XRD) spectrum has shown Bragg reflections which are comparable with the HA. Energy dispersive X-ray (EDX) studies have confirmed calcium/phosphate stoichiometric ratio of HA. The thermogravimetric analysis (TGA) has shown about 74% of inorganic crystals in the nanocomposite formed. These results have revealed that gelatin–chitosan capped gold nanoparticles, acted as a matrix for the growth of HA.     

Organic‐inorganic hybrids based on phenanthrene‐functionalized gold nanoparticles for OLEDs

The electroluminescence intensity of the phenanthrene‐functionalized gold nanoparticles, PMPT‐Au nanoparticles/CPB: Ir(PIA)₂ (acac) film, was increased by 4.9 times compared with control device, CPB: Ir(PIA)₂ (acac) due to coupling between the excitons of emissive layer and localized surface plasmonic resonance of PMPT‐Au NPs. The maximum luminous efficiencies of devices II to IV with PMPT‐Au NPs were 39.2 cd A^?1 (11.8 V), 40.1 cd A^?1 (10.5 V), and 43.1 cd A^?1 (9.0 V), respectively. The increment of current efficiency with PMPT‐Au NP coated devices was strongly related to the energy transfer between the radiated light generated from CBP: Ir(PIA)₂ (acac) emissive layer and localized surface plasmonic resonance excited by PMPT‐Au NP layer.     

Synthesis and characterization of HN(SPiPr2)(SePPh2) and [Te[N(SPiPr2)(SePPh2)]2

The compound HN(SP(i)Pr(2))(SePPh(2)) has been synthesized from the reaction of Ph(2)P(Se)NH(2) with (i)()Pr(2)P(S)Cl in the presence of NaH in THF. HN(SP(i)Pr(2))(SePPh(2)) crystallizes with eight formula units in space group Pbca of the orthorhombic system in a cell of dimensions at -120 degrees C of a = 9.9560(6) A, b = 17.9053(10) A, c = 22.4156(13) A, and V = 3995.9(4) A(3). The square-planar Te(II) complex [Te[N(SP(i)Pr(2))(SePPh(2))](2)] has been isolated from the reaction of Te(tu)(4)Cl(2) x 2H(2)O (tu = thiourea) with the anion [N(SP(i)Pr(2))(SePPh(2))](-), generated in situ from HN(SP(i)Pr(2))(SePPh(2)) in the presence of KO(t)Bu. [Te[N(SP(i)Pr(2))(SePPh(2))](2)] is dimorphic, crystallizing with one formula unit in space group P1 of the triclinic system in a cell of dimensions at -120 degrees C of a = 9.8476(9) A, b = 10.3296(9) A, c = 11.3429(10) A, alpha = 101.903(1) degrees, beta = 115.471(1) degrees, gamma = 92.281(2) degrees, and V = 1008.4(2) A(3) and also crystallizing with two formula units in space group P2(1)/n of the monoclinic system in a cell of dimensions at -120 degrees C of a = 8.7931(5) A, b = 17.1830(10) A, c = 14,1026(9) A, beta = 104.696(1) degrees, and V = 2061.1(2) A(3). In each instance, the [Te[N(SP(i)Pr(2))(SePPh(2))](2)] molecule possesses a center of symmetry, comprising a Te center liganded in a trans manner by two bidentate N(SP(i)Pr(2))(SePPh(2)) groups. However, the (31)P, (77)Se, and (125)Te NMR spectra of [Te[N(SP(i)Pr(2))(SePPh(2))](2)] show two sets of resonances at 25 degrees C. The (31)P VT NMR spectra show two sets of resonances between -50 and +50 degrees C that coalesce between 80 and 100 degrees C, consistent with the presence of the cis as well as the trans isomer in solution.     

NLOphoric Carbazole-Containing Push-Pull Extended Styryl Chromophores: Study of Photophysical Properties by Solvatochromic and DFT Method

Carbazole based extended Donor-π-Acceptor styryl dyes with intramolecular charge transfer characteristics were examined for their linear and nonlinear optical properties using solvatochromism, shifts in emission and density functional theory computations. All the extended styryls demonstrated positive solvatochromism. The extended styryl dyes showed largely improved photophysical properties and large Stokes shifts. The donor-acceptor interactions of the extended styryls were investigated by using generalized Mulliken-Hush method. Oscillator strengths and transition state dipole moments have been studied to understand charge transfer within the molecules. The nonlinear optical properties of the extended styryl were investigated by solvatochromic and density functional theory method.     

Triphenyl borate catalyzed synthesis of amides from carboxylic acids and amines

Herein we report triphenyl borate as a new catalyst for synthesis of amides by catalytic condensation of carboxylic acids and amines. Our protocol is applicable for synthesis of wide range of amides furnishing excellent yields up to 92%. In addition developed method requires low catalyst loading, short time, less amount of solvent, works under air atmosphere and notably no need of azeotropic reflux using special Dean Stark apparatus or molecular sieves.