<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

Dual-room-temperature phosphorescence (DRTP) from organic molecules is of utmost importance in chemical physics. The Dexter-type triplet-to-triplet energy transfer mechanism can therefore be used to achieve DRTP at ambient conditions. Here, we report two donor–acceptor (D–A)-based guests (CQN1, CQN2) in which the donor (D) and acceptor (A) parts are held in angular orientation around the C–N single bond. Spectroscopic analysis along with computational calculations revealed that both guests are incapable of emitting either thermally activated delayed fluorescence (TADF) or RTP at ambient conditions due to large singlet–triplet gaps, which are presented to show host (benzophenone, BP)-sensitized DRTP via multiple intermolecular triplet-to-triplet energy transfer (TTET) channels that originate from the triplet state (T1BP) of BP to the triplet states (T1D, T1A) of the D and A parts (TTET-I:T1BP → T1D; TTET-II:T1BP → T1A). In addition, an intramolecular TTET channel that occurs from the T1D to T1A states of the D and A parts of CQN2 is also activated due to the low triplet (T1D)–triplet (T1A) gap at ambient conditions. The efficiency of TTET processes was found to be 100%. The phosphorescence quantum yields (ϕP) and lifetimes (τP) were shown to be 13–20% and 0.48–0.55 s, respectively. Given the high lifetime of the DRTP feature of both host–guest systems (1000:1 molar ratio), a data security application is achieved. This design principle provides the first solid proof that DRTP via radiative decay of the dark triplet states of the D and A parts of D–A-based non-TADF systems is possible, revealing a method to increase the efficiency and lifetime of DRTP. © 2022 The Authors. Published by American Chemical Society

World University root node

Chemistry

ACS Omega

Molecular-Level Understanding of Dual-RTP via Host-Sensitized Multiple Triplet-to-Triplet Energy Transfers and Data Security Application

Amber Habib describes the hierarchical structure of mathematical knowledge and comments upon its reliability and validity. He invites the reader to a consideration of mathematics’ fundamental components: axioms, proofs, and theorems. Habib asserts that all mathematicians work with a common choice of axioms and rules of logic; and the degree of agreement amongst them is not found in any other discipline. He scrutinises the common view of mathematical activity and knowledge-making as offering certainty and increased rigour. The chapter is then centred around three fundamental issues: problems of ahistoricity, the subject matter proper of mathematics, and its relevance or importance. © 2023 selection and editorial matter, Gita Chadha and Renny Thomas.

Mathematics

Mapping Scientific Method: Disciplinary Narrations

THE METHODS OF MATHEMATICS

We present photoabsorption (PA) response and resistive switching (RS) behavior of ZnO thin films that were ion implanted, at many fluences, with 50 keV Ti ions. Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), UV–Visible spectroscopy and conductive- Atomic Force Microscopy (c-AFM) have been utilized to study the role of oxygen vacancies (OV ) in the evolution of the PA and RS properties. Grazing incidence X-ray diffraction (GIXRD) and Raman Scattering results suggest an improvement in the crystallinity of the films with ion fluence. Enhancement in oxygen vacancy, with fluence, appears to be responsible for higher photo response in the UV–Vis range. Additionally, engineering of bandgap, exhibiting systematic reduction in bandgap- energy with fluence, introduces enhanced absorption in visible regime. For the films implanted at the highest fluence, an asymmetric RS behavior is observed. A Switching behavior, from a high resistance state to a low resistance state, is demonstrated under positive bias conditions. However, for negative bias conditions a rectifying nature is seen. Oxygen vacancies play a crucial role in the modulation of PA response as well as in RS mechanism. Migration of these oxygen vacancies contribute to the formation of conducting filament which may be crucial for the observation of RS phenomenon at the highest fluence. © 2021 Elsevier Ltd and Techna Group S.r.l.

Physics

Ceramics International

Resistive switching properties and photoabsorption behavior of Ti ion implanted ZnO thin films

Selenium (Se), an essential trace element present in several antioxidant enzymes, is responsible for protecting cells from oxidative damage. In the recent past, a large number of naturally inspired Se-containing biomimetic molecular oxidation catalysts have been developed. In this report, a selenium-doped graphitic material (Se-DG) was synthesized using glucose and benzeneseleninic acid (BSA) via a simple hydrothermal method. Se-DG has shown glutathione peroxidase (GPx)-like activity and carried out epoxidation of various aromatic and aliphatic alkenes using H2O2, a green oxidant. In most cases, ∼90% conversion with ∼75% yield of epoxide was achieved in acetonitrile medium. The adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) with hydroperoxyl radical ( OOH) was observed in HRMS which confirmed that the Se-DG produced OOH from H2O2via hydrogen atom abstraction (HAA). A mechanistic insight of the olefin epoxidation was described in the presence of hydrocarbons and it was observed that the hydroxyl radical ( OH) generated during the epoxidation facilitated C-H activation successfully. The plausible reaction mechanism of epoxidation was established with density functional theory (DFT) using Gaussian code. © 2022 The Royal Society of Chemistry

Catalysis Science and Technology

Peroxide activation by selenium-doped graphite

An expression for the subdifferential set of the joint numerical radius of a tuple of matrices is obtained. Its applications to the Birkhoff-James orthogonality in the space consisting of tuples of matrices equipped with the joint numerical radius norm are discussed. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

Linear and Multilinear Algebra

Subdifferential set of the joint numerical radius of a tuple of matrices

Wildlife corridors in a landscape include local vegetation, topography, prey base, water and are associated with isolated wildlife habitat patches. They facilitate maintenance of ecological structure and function as well as provide connectivity to faunal populations supporting genetic transfers, and are elements critical to wildlife management. In this work, habitat patches for tiger, both inside as well as outside of Protected Areas have been identified by developing a Habitat Suitability Index model utilizing Remote Sensing and Geographical Information System datasets for the Terai Arc landscape, India. By using a computational approach based on the framework of theory of complex networks, for exclusively pairwise interactions between the habitat patches, a potential tiger corridor network has been structurally identified and studied in this landscape. The interactions between these habitat patches on a spatial scale has been analyzed as a clique of the corridor network. Further, the Clique Percolation Method has been applied to detect overlapping communities of habitat patches in the landscape. The Cliques required for maintaining contiguity between the habitat patches in order to support tiger movement are validated using field observations of tiger communities within the landscape matrix. The model developed for identification of tiger corridors in this study could potentially be of a vital importance for wildlife stakeholders to better understand and manage tiger populations both within and outside of protected areas. The study also highlights Critical Habitat Patches and their importance in maintaining landscape connectivity for tiger dispersal in the landscape. Using a report published by the Government of India as a benchmark, the model presented in the work is found to have an accuracy of 90.73% in predicting tiger carrying patches and the corridor network in the focal landscape. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

Geocarto International

Geospatial modelling of overlapping habitats for identification of tiger corridor networks in the Terai Arc landscape of India

The matrix M of a linear complementarity problem can be viewed as a payoff matrix of a two-person zero-sum game. Lemke's algorithm can be successfully applied to reach a complementary solution or infeasibility when the game satisfies the following conditions: (i) Value of M is equal to zero. (ii) For all principal minors of MT (transpose of M) value is non-negative. (iii) For any optimal mixed strategy y of the maximizer either yi > 0 or (My)i > 0 for each coordinate i. © 2022 World Scientific Publishing Company.

International Game Theory Review

A Note on Linear Complementarity via Two-Person Zero-Sum Games

The double-membrane-bound architecture of mitochondria, essential for ATP production, sub-divides the organelle into inter-membrane space (IMS) and matrix. IMS and matrix possess contrasting oxido-reductive environments and discrete protein quality control (PQC) machineries resulting inherent differences in their protein folding environments. To understand the nature of stress response elicited by equivalent proteotoxic stress to these sub-mitochondrial compartments, we took misfolding and aggregation-prone stressor proteins and fused it to well described signal sequences to specifically target and impart stress to yeast mitochondrial IMS or matrix. We show, mitochondrial proteotoxicity leads to growth arrest of yeast cells of varying degrees depending on nature of stressor proteins and the intra-mitochondrial location of stress. Next, by employing transcriptomics and proteomics, we report a comprehensive stress response elicited by stressor proteins specifically targeted to mitochondrial matrix or IMS. A general response to proteotoxic stress by mitochondria-targeted misfolded proteins is mitochondrial fragmentation, and an adaptive abrogation of mitochondrial respiration with concomitant upregulation of glycolysis. Beyond shared stress responses, specific signatures due to stress within mitochondrial sub-compartments are also revealed. We report that stress-imparted by bipartite signal sequence-fused stressor proteins to IMS, leads to specific upregulation of IMS-chaperones and TOM complex components. In contrast, matrix-targeted stressors lead to specific upregulation of matrix-chaperones and cytosolic PQC components. Finally, by systematic genetic interaction using deletion strains of differentially upregulated genes, we found prominent modulatory role of TOM complex components during IMS-stress response. In contrast, VMS1 markedly modulates the stress response originated from matrix. © 2022

Life Sciences

Journal of Molecular Biology

Stress Responses Elicited by Misfolded Proteins Targeted to Mitochondria

Memristors are one of the fastest developing electronic devices in the field of data storage and brain inspired neural computing. As a two terminal device, memristors are numerously utilized as resistive random access memories (RRAM) and energy efficient artificial synapses. Herein, the fabrication of perovskite-type rubidium lead chloride quantum dots (RPCQDs) is reported as a functional layer in a memristive system. The device, Al/RPCQDs/indium doped tin oxide (ITO), exhibits a cycling-induced decrease in SET voltage, where Al and ITO work as a top and bottom electrode respectively. However, time dependent self-recovery to the pristine state is observed in the Al/RPCQDs/ITO device. In contrast, the self-rejuvenation is suppressed when a buffer capped conducting polymer (BCCP) is incorporated on the ITO layer to make a Al/RPCQDs/BCCP/ITO structure. This customized device structure successfully retains the reproducible bipolar switching behavior without severe deviation in operating voltages, which helps in studying reliable memristive properties. In addition, the Al/RPCQDs/BCCP/ITO memristive device also demonstrates some essential synaptic functions such as pair-pulse facilitation, long-term potentiation, and long-term depression. © 2022 Wiley-VCH GmbH.

Advanced Electronic Materials

Influence of Nanoscale Charge Trapping Layer on the Memory and Synaptic Characteristics of a Novel Rubidium Lead Chloride Quantum Dot Based Memristor

Nanostructures of layered 2D materials have been proven one of the significant recent trends for visible-light-driven photocatalysis because of their unique morphology, effective optical adsorption, and rich active sites. Herein, we synthesized ultrathin-layered MoS2 nanoflowers and nanosheets with rich active sites by using a facile hydrothermal technique. The photocatalytic performance of the as-synthesized MoS2 nanoflowers (NF) and nanosheets (NS) were investigated for the photodegradation of MB (methylene blue), MG (malachite Green), and RhB (rhodamine B) dye under visible light irradiations. Ultrathin-layered nanoflowers showed faster degradation (96% in 150 min) in RhB under visible light irradiation, probably due to a large number of active sites and high available surface area. The kinetic study demonstrated that the first-order kinetic model best explained the process of photodegradation. The MoS2 nanoflowers catalysts has similar catalytic performance after four consecutive cyclic performances, demonstrating their good stability. The results showed that the MoS2 nanoflowers have outstanding visible-light-driven photocatalytic activity and could be an effective catalyst for industrial wastewater treatment. © 2022 American Chemical Society. All rights reserved.