High Seebeck coefficient and ultra-low lattice thermal conductivity in Cs2InAgCl6

The elastic, electronic and thermoelectric properties of indium-based double-perovskite halide, Cs2InAgCl6 have been studied by first principles study. The Cs2InAgCl6 is found to be elastically stable, ductile, anisotropic and relatively low hard material. The calculated direct bandgap 3.67 eV by TB-mBJ functional fairly agrees with the experimentally measured value 3.3 eV but PBE functional underestimates the bandgap by 1.483 eV. The relaxation time and lattice thermal conductivity have been calculated by using relaxation time approximation (RTA) within the supercell approach. The lattice thermal conductivity (\k{appa}l) is quite low (0.2 Wm-1K-1). The quite low phonon group velocity in the large weighted phase space, and high anharmonicity (large phonon scattering) are responsible for small \k{appa}l. The room temperature Seebeck coefficient is 199 {\mu}VK-1. Such high Seebeck coefficient arises from the combination of the flat conduction band and large bandgap. We obtain power factors at 300K by using PBE and TB-mBJ potentials are ~29 and ~31 mWm-1K-2, respectively and the corresponding thermoelectric figure of merit of Cs2BiAgCl6 are 0.71 and 0.72. However, the maximum ZT value obtained at 700K is ~0.74 by TB-mBJ potential. The obtained results implies that Cs2InAgCl6 is a promising material for thermoelectric device applications.Comment: 19 pages. arXiv admin note: text overlap with arXiv:1801.0370

Geometrical design of stand pipe air distributors for the combustion of municipal solid waste in a fluidised bed

The new geometrical design of stand-pipe air distributor for the combustion of the municipal solid waste was presented. The new design of the air distributors enables penetration of incombustible and unburnt carbon through opening between the air distributors, thus providing easy maintenance work. The fluidized bed experimental rig was constructed using Perspex column in which air was supplied through the distributors below it. In order to establish the final geometrical design of the air distributors, several design parameters were investigated. The effect of orifice size, distance between orifice and distance between distributor pipes on the fluidization behaviour were studied. Investigation on the effects of various orifice sizes of 1.5 mm, 2 mm, 3 mm, 4 mm and 5 mm showed that the 3 mm orifice size exhibited the most stable fluidization behaviour. Investigation on some selected orifice distances of 10 mm, 20 mm, 30 mm and 40 mm also found that the 10 mm orifice distance exhibited stable growths of bubbles. Various pipe distances of 30 mm, 40 mm, 50 mm, 60 mm and 70 mm were also investigated and the most suitable pipe distance was 70 mm

Bounds on R-parity violating SUSY Yukawa couplings from semileptonic decays of baryons

We consider tree-level corrections to hypercharge changing semileptonic decays of certain baryons induced by a minimal supersymmetric standard model with explicitly broken R-parity via $L$-violation. This study leads to a new set of constraints on the products of couplings arising from the LQd$^c$ operator of the superpotential.Comment: Latex (8 pages), no figur

Capital Markets and Foreign Ownership Restrictions: An Empirical Analysis of Emerging Stock Markets

In the 1990s, the hot issue in international finance was the growing interest of portfolio managers in the emerging stock markets. The interest in the emerging markets gained rapid attention, which is evident from the global trends, towards the opening up of economies and financial markets, free capital flow and the privatisation of financial institutions. Earlier the emerging markets were isolated due to several factors that had posed serious problems for international investors. These markets lacked the depth, regulatory framework, and structural safeguards that had characterised the equity markets in the developed world. Capital markets are called integrated, if assets with perfectly correlated rates of returns have the same price regardless of the location in which they are traded. Alternatively, capital market are called segmented, if financial assets traded in different markets “with identical risk characteristics” have different returns due to different investment restrictions.1 Segmentation may be due to individuals’ attitudes, government restrictions over capital movements or irrationality. In the past twenty-five years, modern finance theory has proved to be a major development in finance, which comprises of portfolio theory, capital market theory and efficient market theory. These modern developments can be traced back to the work of Markowitz (1959); Sharpe (1964); Solnik (1974) etc., which assumes that security prices fully reflect all publicly available information. Due to this information, potential investors can gain benefits through international diversification. The major attraction of forming international portfolios lies in the potential for risk reduction through diversification of unsystematic risk.

First-principles prediction of extraordinary thermoelectric efficiency in superionic Li2SnX3(X=S,Se)

Thermoelectric materials create an electric potential when subject to a temperature gradient and vice versa hence they can be used to harvest waste heat into electricity and in thermal management applications. However, finding highly efficient thermoelectrics with high figures of merit, zT$\geq$1, is very challenging because the combination of high power factor and low thermal conductivity is rare in materials. Here, we use first-principles methods to analyze the thermoelectric properties of Li$_2$Sn$X_3$ ($X$=S,Se), a recently synthesized class of lithium fast-ion conductors presenting high thermal stability. In p-type Li$_2$Sn$X_3$, we estimate highly flat electronic valence bands that render high Seebeck coefficients exceeding 400 ${\mu}$VK$^{-1}$ at 700K. In n-type Li$_2$Sn$X_3$, the electronic conduction bands are slightly dispersive however the accompanying weak electron-acoustic phonon scattering induces high electrical conductivity. The combination of high Seebeck coefficient and electrical conductivity gives rise to high power factors, reaching a maximum of 4 mWm$^{-1}$K$^{-2}$ in p-type Li$_2$SnS$_3$ and 8 mWm$^{-1}$K$^{-2}$ in n-type Li$_2$SnSe$_3$ at 300 K. Likewise, the thermal conductivity in Li$_2$Sn$X_3$ is low as compared to conventional thermoelectric materials, 2-5 Wm$^{-1}$K$^{-1}$ at room temperature. As a result, we estimate a maximum zT = 1.05 in p-type Li$_2$SnS$_3$ at 700 K and an extraordinary 3.07 (1.5) in n-type Li$_2$SnSe$_3$ at the same temperature (300 K). Our findings of huge zT in Li$_2$Sn$X_3$ suggest that lithium fast-ion conductors, typically employed as electrolytes in solid-state batteries, hold exceptional promise as thermoelectric materials.Comment: 21 Page

Empathy and Role Modeling. is IT Missing?

Let me start by congratulating the dedicated team of Pakistan Journal of Surgery and Medicine (PJSM) whose untiring effort brought this journal of International standard. I have the honor to be part of this professional and enthusiastic galaxy of highly intellectual writers. Insha'Allah you will witness the glory of this journal very soon