Energy band engineering of flexible gallium arsenide through substrate cracking with pre‐tensioned films

Flexible electronics based on the otherwise rigid conventional crystalline semiconductors is emerging as a new class of technology. However, the existing layer‐transfer approaches for implementing such technologies is mostly focused on maintaining the performance of the original device. Here we show that layer transfer through substrate cracking with a pre‐tensioned nickel film readily enables the manipulation of the electronic band structure in flexible gallium arsenide (GaAs) devices. We empirically and theoretically quantify the effect of ‘engineered' residual strain on the electronic band structure in these flexible GaAs devices. Photoluminescence and quantum efficiency measurements indicate the widening of the GaAs energy bandgap due to the residual compressive strain. The experimental results are in good agreement with our theoretical calculations. This study introduces a new way for strain engineering in flexible compound semiconductors with important implications for electronic and optoelectronic applications. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Minimal perturbation approach implementation in spectral methods

Pseudospectra and minimal perturbation approach (MPA) principles are used and implemented to provide more stability and more rigorous mathematical foundations for the functional expansion multi-domain spectral method (MDSM). The implemented formulation is used to analyze optical waveguides and semiconductor quantum wells. The results show that MDSM formulation based on the MPA is very stable and slightly more accurate as compared to the Tau MDSM.     

Non-isothermal crystallization kinetics of poly(3-hydroxybutyrate)/EVA 80 blends enhanced by NH4Cl as a nucleating agent

Journal of Thermal Analysis and Calorimetry - The crystallization kinetics of poly(3-hydroxybutyrate) (PHB), PHB/NH4Cl composites, PHB/ethylene-vinyl acetate (EVA 80) blends and PHB/EVA 80/1 mass%...     

Analysis of <Superscript>8</Superscript>B Proton Halo Nucleus Scattered from <Superscript>12</Superscript>C and <Superscript>58</Superscript>Ni at Different Energies

Angular distributions in the elastic scattering of ⁸B from ¹²C and ⁵⁸Ni targets at different energies have been analyzed in the framework of the double-folding (DF) optical model. The real central part of the nuclear optical potential is obtained by folding the M3Y effective interaction with the cluster density distribution of the ⁸B nucleus. The experimental angular distributions have been successfully reproduced. This confirms the validity of the cluster structure of the ⁸B nucleus.     

Natural radioactivity measurements and age-dependent dose assessment in groundwater from Al-Zulfi,Al-Qassim and Al-Majmaah regions,Saudi Arabia

In this study, the levels of natural radioactivity in the groundwater samples collected from 26 different locations in Al-Zulfi, Al-Qassim and Al-Majmaah regions were determined. The estimated average values of ²²⁶Ra, ²²⁸Ra, ⁴⁰K, gross α and gross β activities in the samples were 0.87 Bq L^?1, 1.33 Bq L^?1, 4.22 Bq L^?1, 36.82 mBq L^?1 and 831.91 mBq L^?1, respectively. We found that age-dependent effective ingestion dose from radionuclides in all samples were higher than WHO recommended levels of 0.1 µSv y^?1 for adults 0.2 µSv y^?1 for children and 0.26 µSv y^?1 for infants while 20 sampling locations have age-dependent effective dose equivalent from β contributors were higher than WHO recommended level of 0.1 mSv y^?1.     

Weak lignin-binding enzymes

Economic barriers preventing commercialization of lignocellulose-to-ethanol bioconversion processes include the high cost of hydrolytic enzymes. One strategy for cost reduction is to improve the specific activities of cellulases by genetic engineering. However, screening for improved activity typically uses “ideal” cellulosic substrates, and results are not necessarily applicable to more realistic substrates such as pretreated hardwoods and softwoods. For lignocellulosic substrates, nonproductive binding and inactivation of enzymes by the lignin component appear to be important factors limiting catalytic efficiency. A better understanding of these factors could allow engineering of cellulases with improved activity based on reduced enzyme-lignin interaction (“weak lignin-binding cellulases”). To prove this concept, we have shown that naturally occurring cellulases with similar catalytic activity on a model cellulosic substrate can differ significantly in their affinities for lignin. Moreover, although cellulose-binding domains (CBDs) are hydrophobic and probably participate in lignin binding, we show that cellulases lacking CBDs also have a high affinity for lignin, indicating the presence of lignin-binding sites on the catalytic domain.     

An explicit FDM calculation of nonparabolicity effects in energy states of quantum wells

An explicit finite difference method (FDM) to solve the nonparabolic effective mass approximation of Schrodinger wave equation (SWE) for arbitrary quantum wells (QWs) is presented. The explicit nature of the presented method and its sparse matrices allow fast computation for energy states in QWs. The nonparabolicity effects are considered explicitly without iteration. This in turn results in faster and more stable calculations. The method is used to study the nonparabolicity effects in energy states and states overlapping in asymmetric AlGaAs/GaAs QWs.     

Meshfree eigenstate calculation of arbitrary quantum well structures

A new, explicit, efficient, and meshfree multi-domain spectral method (MDSM) is presented to calculate the eigenstates of arbitrary semiconductor quantum wells (QW). The method is functional expansion based where the quantized energy states are approximated using efficient basis sets and the boundaries are considered using Tau approach. For bounded domains, Chebyshev polynomials and power series are used as the basis sets, while non-orthogonal predefined exponential basis sets are used for the half bounded domains. Many QW structures were studied and the results are compared with published results for validation. The comparisons exhibit the accuracy and efficiency of the presented method. For QWs that can be analyzed analytically, the relative errors in the calculated quantized energy levels are in the order of ¹⁰−12 with very small number of bases in few ms.     

Novel lanthanum sulfide–decorated zirconia nanohybrid for enhanced electrochemical oxygen evolution reaction

Journal of Solid State Electrochemistry - Metal sulfide and oxides have drawn interest as economical substitutes to noble metal catalysts due to their ability for oxygen evolution reaction (OER)...