Physics

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A truncation of a Haar distributed orthogonal random matrix gives rise to a matrix whose eigenvalues are either real or complex conjugate pairs, and are supported within the closed unit disk. This is also true for a product Pm of m independent truncated orthogonal random matrices. One of most basic questions for such asymmetric matrices is to ask for the number of real eigenvalues. In this paper, we will exploit the fact that the eigenvalues of Pm form a Pfaffian point process to obtain an explicit determinant expression for the probability of finding any given number of real eigenvalues. We will see that if the truncation removes an even number of rows and columns from the original Haar distributed orthogonal matrix, then these probabilities will be rational numbers. Finally, based on exact finite formulas, we will provide conjectural expressions for the asymptotic form of the spectral density and the average number of real eigenvalues as the matrix dimension tends to infinity. © 2018 Taylor &amp; Francis.

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Experimental Mathematics

How Many Eigenvalues of a Product of Truncated Orthogonal Matrices are Real?

We show in this paper that the basic representations of position and momentum in a quantum mechanical system, that are guided by a generalized uncertainty principle and lead to a corresponding one-parameter eigenvalue problem, can be interpreted in terms of an extended Schrödinger equation embodying momentum-dependent mass. Some simple consequences are pointed out. © Published under licence by IOP Publishing Ltd.

Journal of Physics: Conference Series

Generalized Uncertainty Principle and Momentum-Dependent Effective Mass Schrödinger Equation

Working within the framework of parity-time-symmetric quantum mechanics, we look into the possibility of entanglement generation and demonstrate that the feature of non-violation of no-signaling principle may hold for the simplest nontrivial case of bipartite systems. Basically, our arguments are based on the computation of the reduced density matrix of one party to justify that the entropy of the other does not change. © 2020 World Scientific Publishing Company.

Modern Physics Letters A

Remarks on the preservation of no-signaling principle in parity-time-symmetric quantum mechanics

Microwave synthesized strontium bismuth niobate Sr1-xSnxBi1.95La0.05Nb2O9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn2+) and layer bismuth (Bi3+) generate optimal lattice strain. Lattice oxygen, that is critical in photocatalytic applications, is observed to fold along a-c plane on introducing tin. SSBLN compositions possess higher porosity with reduced dimensions. Porosity derived capacitive boundaries promote polaronic hopping in SSBLN materials over diffused ionic conduction. The visible spectrum photocatalytic response is better after doping tin in SSBLN compositions. Mesoporous network and electron-hole pair generation play crucial role in augmented photocatalytic behaviour of SSBLN materials. © 2020 Elsevier B.V.

Physica B: Condensed Matter

Microwave derived porosity in tin-doped Sr1-xSnxBi1.95La0.05Nb2O9 nano materials for non-Debye conduction and photocatalytic activity

There are abundant sources of metal-oxide-based wastes from industries such as electronics and metal production, which generally have a detrimental effect on the environment when not recycled. In this concise review, we aim to provide a brief overview of the state-of-the-art research on how these metal-oxide wastes are being used by the scientific community in the applications of energy storage, catalysis, and sensing. We focus on three important waste streams: E-waste, waste from the production of metals, such as red mud and slag, and waste from metal recovery, for example, rusted wires and discarded capacitors. We review some promising routes for obtaining high-quality metal-oxide nanoparticles and nanowires and critically review potential pitfalls that hinder the wide-scale application of these waste-streams. © 2020 John Wiley &amp; Sons Ltd

International Journal of Energy Research

Metal-oxide nanomaterials recycled from E-waste and metal industries: A concise review of applications in energy storage, catalysis, and sensing

Bulletin of the American Physical Society

Computational Design and Study of Small DA Type Organic Molecule with Ambipolar Characteristics and Rich Linear and Non-Linear Optical Properties

Despite having the fascinating physical, electronic, and optical properties of two-dimensional (2D) crystals of MoS2, h-BN, and InSe, none of them solely meet all the desired criteria required for high efficiency optoelectronic devices, such as a suitable band gap with very high carrier mobility, a moderate excitonic lifetime, a desirable bending modulus, environmental stability against air and water, etc. Herein, we demonstrate that these fundamental limitations can easily be overcome by building a van der Waals heterostructure (vdW-HS) of monolayer InSe either with single-layer MoS2 or h-BN. Our first-principles calculations suggest that compared to individual monolayers, the examined InSe/MoS2 and InSe/h-BN vdW-HSs are not only thermodynamically and mechanically more robust but also possess improved electronic and optical properties, which can be particularly useful for solar harvesting devices. Importantly, through a systematic study, we elucidate that the band gap and its nature can largely be modulated (∼0.1-1.6 eV, indirect direct, type I type II) for both the examined heterobilayers by applying mechanical strain and transverse electric field. Even more interestingly, we further show that with such bilayer heterostructures it is possible to get electron and hole mobility almost in the same order of magnitude (103-104cm2V-1s-1), either naturally or by applying small biaxial strain. © 2020 American Physical Society.

Physical Review B

Modulation of electronic and transport properties of bilayer heterostructures: InSe/MoS2 and InSe/h -BN as the prototype

This paper investigates the achievable sum rate and the outage capacity of generalized frequency division multiplexing systems (GFDMs) with minimum mean-square error (MMSE) receivers over frequency-selective Rayleigh fading channels. To this end, a Gamma-based approximation approach for the probability density function of the signal-to-interference-plus-noise ratio is presented, based on which accurate analytical formulations for the achievable sum rate and outage capacity are proposed. The accuracy of our analysis is corroborated through Monte Carlo simulation assuming different GFDM parameters. Illustrative numerical results are depicted in order to reveal the impact of the key system parameters, such as the number of subcarriers, number of subsymbols, and roll-off factors, on the overall system performance. © 2020 IEEE.

IEEE International Conference on Communications

Achievable Sum Rate and Outage Capacity of GFDM Systems with MMSE Receivers

In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications. In particular, the effect of thickness ratio (e.g. in Al : a-Si, the ratio of the Al and a-Si layer thickness) and temperature during irradiation on crystallization of the Si films has been explored for the first time. Two sets of samples with thickness ratio 1 : 1 (set-A: 50 nm Al/50 nm a-Si) and thickness ratio 1 : 3 (set-B: 50 nm Al/150 nm a-Si) have been prepared on thermally oxidized Si-substrates. In one experiment, thermal annealing of the as-prepared sample (of both the sets) has been done at different temperatures of 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C. Significant crystallization was found to initiate at 200 °C with the help of thermal annealing, which increased further by increasing the temperature. In another experiment, ion irradiation on both sets of samples has been carried out at 100 °C and 200 °C using 100 MeV Ni7+ ions with fluences of 1 × 1012 ions per cm2, 5 × 1012 ions per cm2, 1 × 1013 ions per cm2, and 5 × 1013 ions per cm2. Significant crystallization of Si was observed at a remarkably low temperature of 100 °C under ion irradiation. The samples irradiated at 100 °C show better crystallization than the samples irradiated at 200 °C. The maximum crystallization of a-Si has been observed at a fluence of 1 × 1012 ions per cm2, which was found to decrease with increasing ion fluence at both temperatures (i.e. 100 °C &amp; 200 °C). The crystallization of a-Si is found to be better for set-B samples as compared to set-A samples at all the fluences and irradiation temperatures. The present work is aimed at developing the understanding of the crystallization process, which may have significant advantages for designing crystalline layers at lower temperature using appropriate masks for irradiation at the desired location. The detailed mechanisms behind all the above observations are discussed in this paper. © 2020 The Royal Society of Chemistry.

RSC Advances

An assessment on crystallization phenomena of Si in Al/a-Si thin films: Via thermal annealing and ion irradiation

Titania–zeolite Y composites were synthesized by a facile solid-state dispersion method. The synergistic effects of porous zeolite structure and novel photocatalysis properties of titania nanoparticles were exploited. The physical properties of the composites were characterized by scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, diffuse reflectance spectroscopy, fourier transform infra-red spectroscopy and photoluminescence spectroscopy. Porosity and surface area of the composites were determined from Brunauer–Emmett–Teller studies. The antibacterial effect and the photocatalysis properties of these composites were studied. Composites exhibited higher growth reduction of Escherichia coli and Staphylococcus aureus as compared with the pure forms (P25 titania and zeolite Y). Maximum growth reduction of both types of bacterial cells (gram-positive as well as gram-negative) was observed with 20\% titania–zeolite composite. The composite demonstrated 40 and 30\% enhancement in the growth reduction of E. coli and S. aureus, respectively, as compared with the pure forms; 10\% composite exhibited 50\% enhancement in the photocatalysis efficiency of methylene blue dye degradation as compared with P25 titania nanoparticles and led to a complete removal of the dye in the first 60 min of photocatalysis process. Mechanisms for both applications have been proposed in light of the observed results. © 2020, Indian Academy of Sciences.