<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

(SoNS) School of Natural Sciences

Perovskite solar cells (PSCs) exhibit the steepest growth in power conversion efficiency among the existing photovoltaic technologies. However, a wide range of factors restrict the commercial viability of PSCs as a renewable energy source. This article reviews the latest progress in PSC devices including innovative light-harvesting perovskite materials and advanced interfacial layers, and the foremost challenges. The most promising remedial solutions to challenges are also discussed. For the realization of a high performing and eco-friendly stabilized perovskite photovoltaic device, a combinational method involving multiple restorative solutions is required. A specific emphasis is given to unveiling interesting perovskite properties, and device fabrication approaches to the solutions. These remedies and strategies may help researchers to select appropriate methods and design their experiments to obtain a high photo-conversion efficiency in photovoltaic devices with enhanced stability as compared to conventional photovoltaic devices. © 2021 Wiley-VCH GmbH

World University root node

Physics

Advanced Energy Materials

Emerging Perovskite Solar Cell Technology: Remedial Actions for the Foremost Challenges

Surface sensitive Aurivillius materials are investigated in the present work for tailorable IR-activity, carbon contamination and supplemented UV-Vis absorption besides having broad PTC signature. Introduction of tantalum onto niobium sites strengthens octahedron rigidity and checks oxygen leaving unit cell positions to occupy surface interstitials. High solid solubility between tantalum and niobium oxide compounds permits systematically increasing unit cell volume. Optical and electrical energy bandgaps are investigated on doping tantalum besides tailoring IR-activity of unit cell. Equal doped sample with x=1.0 offers broadened PTC region by nearly 400% compared to other samples. Energy states are estimated to overlap in diffused manner on doping tantalum to increase amount of UV-Vis spectrum absorption in x=1.0 material. Differential thermal analysis (DTA) was used to confirm diffused phase transition behavior with release in lattice strain on doping tantalum in SrBi1.98La0.02Nb1-xTaxO9 (SBLNT) materials. © 2021 Author(s).

AIP Conference Proceedings

Broadening of PTC signature with augmented UV-VIS optical absorption in carbophobic SrBi1.98La0.02Nb-TaO9material

In general, the approximation of Discrete Cosine Transform (DCT) is used to decrease computational complexity without impacting its efficiency in coding. Many of the latest algorithms used in DCT approximation functions have only a smaller DCT length transform of which some are non-orthogonal. For computing DCT orthogonal approximation, a general recursive algorithm is used here, and its length is obtained using DCT pairs of length N/2 of N addition cost in input pre-processing. The recursive sparse matrix has been decomposed by using the vector symmetry from the DCT basis in order to achieve the proposed approximation algorithm that is highly scalable to enforce the highest lengths software and hardware by using a current 8-point approximation to obtain a DCT approximation with two-length power, N>8. © Published under licence by IOP Publishing Ltd.

Journal of Physics: Conference Series

VLSI Implementation of Discrete Cosine Transform Approximation Recursive Algorithm

For a unital C*-algebra A and a subspace B of A, a characterization for a best approximation to an element of A in B is obtained. As an application, a formula for the distance of an element of A from B has been obtained, when a best approximation of that element to B exists. Further, a characterization for Birkhoff-James orthogonality of an element of a Hilbert C*-module to a subspace is obtained. © 2021 Ramanujan Mathematical Society. All rights reserved.

Mathematics

Journal of the Ramanujan Mathematical Society

Best approximations, distance formulas and orthogonality in C**-algebras

The possibilities of the precise control of wetting properties of a series of laser-induced graphene (LIG) films consisting of microscale air pockets on top of nano-scale surface roughness using electrowetting are demonstrated. By application of a marginal DC bias (∼2 V), water can efficiently wet as well as can be pumped through the superhydrophobic LIG substrates. Interestingly, the electrowetting phenomenon is strongly dependent on the applied voltage polarity and it causes an abrupt wetting transition from superhydrophobic (contact angle ∼152°) Cassie state to superhydrophilic (contact angle ∼7°) Wenzel state on the LIG films. By analyzing the voltage polarity dependent electrowetting results with an equivalent electrical circuit model at the solid-liquid interface, and considering the hierarchical dual surface roughness (micro-nano scale), the transition between the “slippy” Cassie state and the “sticky” Wenzel states is explained. Furthermore, we demonstrate that the unique structural characteristics of the custom-designed micropatterned LIGs, with precisely tailored surface energy by simple post-annealing treatment, enable easy preparation of superhydrophobic LIG films. The approach to prepare stable superhydrophobic LIG with voltage polarity dependent wetting mode transition is used here to controllably transport of water through 3D porous LIG surfaces. © 2021 Elsevier Ltd

Fulltext

Carbon

Polarity dependent electrowetting for directional transport of water through patterned superhydrophobic laser induced graphene fibers

Flu is an acute respiratory infection caused by the influenza virus. The outbreak usually occurs every year in temperate region during the fall and winter seasons, but it is present year-round in tropics. Perceived risk of infection, affordability and lack of awareness among the population results in a low level of vaccination coverage. To control disease transmission and promote vaccination, public health officials use media coverage to spread awareness on vaccine safety, vaccine coverage, disease prevalence in the population through public health websites, advertisements, and other social media web pages. Media coverage acts as an incentive as it helps to decrease overall transmission potential and also at the same time increases the vaccination coverage in the population. Since the public health department has a limited budget, it needs to make optimum allocation of its effort to reduce the total cost of infection. Our paper investigates the effect of media coverage using SIR model of disease transmission. We look at three possible functional relationships - linear, exponential, and hyperbolic - the way media coverage may affect the disease transmission and vaccination rate. We derive necessary conditions of optimal solution using Optimal Control Theory and Pontryagin Maximum Principle (PMP) to minimize the total cost for infection. Analysis of our paper demonstrates that the cost of optimal management is four times less than the cost of constant control effort, and putting more effort into reducing transmission is optimal rather than an effort to increase vaccination at the beginning of the outbreak. Analysis of the role of media coverage under three different scenarios may help in formulating policies for public health programs in mitigating the influenza outbreak. © 2021 World Scientific Publishing Company.

Journal of Biological Systems

ROLE of MEDIA COVERAGE in MITIGATING AN EPIDEMIC OUTBREAK: AN OPTIMAL CONTROL MODEL

Mild blue light-mediated N-H insertion of indole and its derivatives into aryldiazoesters has been reported in a batch and flow strategy to afford the corresponding N-alkylated product in moderate-to-excellent yield. Detailed high-performance liquid chromatography-based reaction kinetics measurements, control experiments, and kinetic isotope effect reveal that 3-substituted indoles with electron-withdrawing groups such as -CN and -CHO facilitated the product formation, whereas the electron-donating group retarded the process. The neutral indole performed in between them. Furthermore, Hammett plot and density functional theory-based transition-state optimization studies showed substantial correlation of the electronic nature of the substituents at the C3 position of indoles with the rate of the N-H insertion reaction. The strategy was utilized to synthesize a key intermediate for the natural product (-)-psychotrimine. ©

Chemistry

Journal of Organic Chemistry

Blue LED-Mediated N-H Insertion of Indoles into Aryldiazoesters at Room Temperature in Batch and Flow: Reaction Kinetics, Density Functional Theory, and Mechanistic Study

Advancement of the memristor-based artificial synapse (AS) is urgently needed for rapid progress in neuromorphic devices. The precise structural and chemical engineering of metal oxide layers by metal dopants (Ni) is presented as an innovative way to set off a decent performance of the AS. An ON/OFF ratio of 103as well as data retention and endurance capabilities of 104s and 103cycles, respectively, are achieved. With these properties, the symmetric alteration in conductance states, short-term plasticity (STP) and long-term plasticity (LTP) are realized within the same device, and compared with the reported values to establish its excellent cognitive behavioural ability. Our combined experimental and the DFT-based first-principles calculation results reveal that the rational designing of AS using metal-cations (Ni) can promote an ultra-low-power of ∼2.55 fJ per pulse (lower than human brain ∼10 fJ per pulse) for STP, promising for next-generation smart memory devices. Here, Ni endorses strong electronic localization, which in turn familiarizes trap states within the forbidden energy gap and improves short-term memory loss. Further, it modifies the local electrostatic barriers to stimulate modulatory action (as commonly observed in the mammalian brain) for LTP. Overall, this work provides a novel pathway to overcome the technological bottleneck. © The Royal Society of Chemistry 2021.

Journal of Materials Chemistry C

Metal-induced progressive alteration of conducting states in memristors for implementing an efficient analog memory: a DFT-supported experimental approach

An annealing temperature-driven appearance of a sharp dual-band edge in the ultraviolet-visible absorption spectrum of electrochemically anodized TiO2 nanotubes (TNTs) and the corresponding impact on the photodegradation of organic dyes is reported based on the evolution of an anatase (A)/rutile (R) phase junction. Systematic X-ray diffraction followed by a micro-Raman analysis illustrates the impact of annealing between 500 and 900 °C in promoting the anatase-to-rutile phase transformation with a higher degree of crystallinity through an evolution of an intermediate mixed phase. X-ray photoelectron spectroscopy (XPS) further reveals a clear transition from the sub-stoichiometric to stoichiometric TNTs with increasing annealing temperature. Moreover, the valence band (VB) XPS along with the ultraviolet photoelectron spectroscopy (UPS) analysis suggests the possible band alignment at the A/R interface, whereas the X-ray absorption spectroscopy (XAS) at the Ti L- and O K-edges confirms a systematic change from an anatase to a rutile phase owing to the modification in local symmetry. To validate our experimental results, especially the formation of a dual-band edge at the A/R phase junction in TNTs, theoretical calculations using density functional theory (DFT) were also performed. Here, a one-to-one analysis of our theoretical and experimental results not only shows a good agreement to each other but also illustrates the microscopic origin behind the formation of a dual-band edge in mixed phase TNTs as well as the observed variation in Raman and XPS spectra with annealing temperature. Finally, an improved photocatalytic degradation of methylene blue aqueous solution is demonstrated in the presence of a mixed phase and explained in the framework of an efficient transfer of photogenerated electrons from the conduction band (CB) of R to the CB of A and holes from the VB of A to the VB of R across the phase junction in tube walls. © 2021 American Chemical Society.

Journal of Physical Chemistry C

Unveiling Temperature-Mediated Dual-Band Edge in TiO2Nanotubes with Enhanced Photocatalytic Effect

<p>Novel strains emerge every year and cause seasonal flu epidemic. These variants exhibit differences in antigenicity and may escape immunity from vaccines and thus invade the population. Here, we devise a discrete population game model of vaccination and transmission of two strains–a resident and a relatively rare mutant–to explain the influence of social behaviour, specifically vaccinating behaviour on the emergence of the mutant strain in the population. Our integrated framework of behaviour-prevalence model exhibits time evolution of two strategic interactions such as individuals' perceived vaccination risk and probability of infection, where both declines as more and more individuals vaccinate in the population. Numerical simulation and analysis of the model show that the predominant Nash strategy allows invasion of the mutant strain under very disparate individuals perceived disease risks from these two pathogens and relatively lower vaccine efficacy against the mutant. The model also demonstrates that invasion of the mutant has a nonlinear dependence on epidemiological characteristics such as the relative force of infection, cross-immunity, perceived cost of treatment and vaccine efficacy. This study exemplifies that adaptive social behaviour is an important component of public health strategic decision-making during the control of the flu-like epidemic. © 2021 Informa UK Limited, trading as Taylor &amp; Francis Group.</p>