Finite SSH chains coupled to a two-level emitter: Hybridization of edge and emitter states

The Hamiltonian for the one-dimensional SSH chain is one of the simplest Hamiltonians that supports topological states. This work considers between one and three finite SSH chains with open boundary conditions that either share a lattice site (or cavity), which -- in turn -- is coupled to a two-level emitter, or are coupled to the same two-level emitter. We investigate the system properties as functions of the emitter-cavity coupling strength $g$ and the detuning between the emitter energy and the center of the band gap. It is found that the energy scale introduced by the edge states that are supported by the uncoupled finite SSH chains leads to a $g$-dependent hybridization of the emitter and edge states that is unique to finite-chain systems. A highly accurate analytical three-state model that captures the band gap physics of $k$-chain ($k \ge 1$) systems is developed. To quantify the robustness of the topological system characteristics, the inverse participation ratio for the cavity-shared and emitter-shared systems consisting of $k$ chains is analyzed as a function of the onsite disorder strength. The $g$-dependent hybridization of the emitter and uncoupled edge states can be probed dynamically.Comment: 10 figure

Application of Ligninolytic Enzymes in the Production of Biofuels from Cotton Wastes

The application of ligninolytic fungi and enzymes is an option to overcome the issues related with the production of biofuels using cotton wastes. In this dissertation, the ligninolytic fungus and enzymes were evaluated as pretreatment for the biochemical conversion of Cotton Gin Trash (CGT) in ethanol and as a treatment for the transformation of cotton wastes biochar in other substances. In biochemical conversion, seven combinations of three pretreatments (ultrasonication, liquid hot water and ligninolytic enzymes) were evaluated on CGT. The best results were achieved by the sequential combination of ultrasonication, hot water, and ligninolytic enzymes with an improvement of 10% in ethanol yield. To improve these results, alkaline-ultrasonication was evaluated. Additionally, Fourier Transform Infrared (FT-IR) and principal component analysis (PCA) were employed as fast methodology to identify structural differences in the biomass. The combination of ultrasonication-alkali hydrolysis, hot liquid water, and ligninolytic enzymes using 15% of NaOH improved 35% ethanol yield compared with the original treatment. Additionally, FT-IR and PCA identified modifications in the biomass structure after different types of pretreatments and conditions. In thermal conversion, this study evaluated the biodepolymerization of cotton wastes biochar using chemical and biological treatments. The chemical depolymerization evaluated three chemical agents (KMnO4, H2SO4, and NaOH), with three concentrations and two environmental conditions. The sulfuric acid treatments performed the largest transformations of the biochar solid phase; whereas, the KMnO4 treatments achieved the largest depolymerizations. The compounds released into the liquid phase were correlated with fulvic and humic acids and silicon compounds. The biological depolymerization utilized four ligninolytic fungi Phanerochaete chrysosporium, Ceriporiopsis subvermispora, Postia placenta, and Bjerkandera adusta. The greatest depolymerization was obtained by C. subvermispora. The depolymerization kinetics of C. subvermispora evidenced the production of laccase and manganese peroxidase and a correlation between depolymerization and production of ligninolytic enzymes. The modifications obtained in the liquid and solid phases showed the production of humic and fulvic acids from the cultures with C. subvermispora. The results of this research are the initial steps for the development of new processes using the ligninolytic fungus and their enzymes for the production of biofuels from cotton wastes

Why So Few Women Directors in Top UK Boardrooms? Evidence and Theoretical Explanations

Using evidence from a survey of women directors in FTSE 100 companies, this paper considers possible explanations for the persistent homogeneity of top UK boards. Only 61 per cent of the top 100 companies had female directors in 2002, down from 64 per cent in 1999. Women held only 3 per cent of executive (= US inside) directorships, and there were only 15 women executive directors in total. Explanations usually include women's lack of ambition, lack of experience and lack of commitment. These have been disproved by research, but underlying theories of social exclusion may provide insight into this persistent phenomenon

Novel multi-stage aluminium production: part 1 � thermodynamic assessment of carbosulphidation of Al<inf>2</inf>O<inf>3</inf>/bauxite using H<inf>2</inf>S and sodiothermic reduction of Al<inf>2</inf>S<inf>3</inf>

© 2017 Institute of Materials, Minerals and Mining and The AusIMM Published by Taylor & Francis on behalf of the Institute and The AusIMMA novel multi-stage Al production through a carbosulphidation of Al2O3, followed by a sodiothermic reduction of Al2S3, was proposed. In Stage-1, alumina (or bauxite) is reduced to Al2S3 in the presence of carbon and H2S. In Stage-2, Al2S3 is reduced to Al through reactions with Na or NaH. The thermodynamic analysis predicted Al2S3 to be the main intermediate Al-compound when H2S is reacted with Al2S3 and C at 1000-2000°C at 1 atm. Al2S3 formation was predicted to be low at 1100-1300°C at 1 atm (0.1 moles/mole Al2O3) but increased with increasing temperature (0.96 moles/mole Al2O3 at 1800°C). The thermodynamic analysis of sodiothermic reduction predicted that Al metal can be extracted from Al2S3 below 800°C at 1 atm. The Na2S produced can be hydrolysed to form H2S and NaOH. H2S can be re-used and the Na can be reproduced from NaOH and put back into the process