<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

Ecosystems are constantly under threat by invasive species which alter existing ecological networks as they spread. We use Geographic Information System methods coupled with complex network analysis to model the movement and spread of Lantana camara in Rajaji Tiger Reserve, India, as understanding spatial aspects of the spread mechanism are essential for better resource management in the region. Lantana mapping was carried out by field observations along multiple transects and plots, and the data generated was used as input for maximum entropy modelling to identify land patches in the study area that are favourable for lantana growth. The patch information so obtained was integrated with a raster map generated by identifying different topographical features in the study area which are favourable for lantana growth. The integrated data was analysed with a complex network perspective, where relatively dense and large potential lantana distribution patches were considered as vertices, connected by relatively sparse and thin potential lantana continuities, identified as edges. The network centrality analysis reveal key patches in the study area that play specialized roles in the spread of lantana in a large region. Hubs in the lantana network are primarily identified as dry seasonal river beds. The lantana network is found to exhibit small-world architecture with a well formed community structure. We infer that the above properties of the lantana network are major contributors in regulating the movement and spread of the plant through the entire region of study. © 2019 Elsevier B.V.

Mathematics

Ecological Complexity

A network theoretic study of potential invasion and spread of Lantana camara in a part of Rajaji Tiger Reserve, India

In recent years, covalent organic frameworks (COFs) have attracted considerable attention due to their crystalline and porous nature, which positions them as intriguing candidates for diverse applications such as catalysis, sensing, or optoelectronics. The incorporation of dyes or semiconducting moieties into a rigid two-dimensional COF can offer emergent features such as enhanced light harvesting or charge transport. However, this approach can be challenging when dealing with dye molecules that exhibit a large aromatic backbone, since the steric demand of solubilizing side chains also needs to be integrated into the framework. Here, we report the successful synthesis of DPP2-HHTP-COF consisting of diketopyrrolopyrrole (DPP) diboronic acid and hexahydroxytriphenylene (HHTP) building blocks. The well-known boronate ester coupling motif guides the formation of a planar and rigid backbone and long-range molecular DPP stacks, resulting in a highly crystalline and porous material. DPP2-HHTP-COF exhibits excellent optical properties including strong absorption over the visible spectral range, broad emission into the NIR and a singlet lifetime of over 5 ns attributed to the formation of molecular stacks with J-type interactions between the DPP subcomponents in the COF. Electrical conductivity measurements of crystalline DPP2-HHTP-COF pellets revealed conductivity values of up to 10 -6 S cm -1 .

World University root node

Chemistry

Fulltext

Chemistry of Materials

Scaffold-Induced Diketopyrrolopyrrole Molecular Stacks in a Covalent Organic Framework

Inspired by the fact that relatively small values of the effective higgsino mass parameter of the Z3-symmetric Next-to-Minimal Supersymmetric Standard Model (NMSSM) could render the scenario ‘natural', we explore the plausibility of having relatively light neutralinos and charginos (the electroweakinos or the ewinos) in such a scenario with a rather light singlino-like Lightest Supersymmetric Particle (LSP), which is a Dark Matter (DM) candidate and singlet-dominated scalar excitations. By first confirming the indications in the existing literature that finding simultaneous compliance with results from the Large Hadron Collider (LHC) and those from various DM experiments with such light states is, in general, a difficult ask, we proceed to demonstrate, with the help of a few representative benchmark points, how exactly and to what extent could such a highly motivated ‘natural' setup with a singlino-like DM candidate still remains plausible.

Physics

Journal of High Energy Physics

Revisiting singlino dark matter of the natural Z 3-symmetric NMSSM in the light of LHC

Riparian landscapes are characterized by heterogeneous geomorphological structures such as erosive and depositional habitats, and therefore, may have variable soil biophysical properties. The heterogeneity in geomorphological structures and related biophysical properties would exert spatial variations in the soil CO2 efflux (SCE). However, studies assessing the relative control of biophysical variables on the SCE under such complex landscapes of dry tropical ecosystems are limited. Therefore, we assessed the effect of heterogeneity in geomorphological structures on SCE, and identified the key biophysical variables governing SCE along the riparian landscapes. The SCE, soil organic C (SOC), microbial biomass C (MBC) and pH were found to vary significantly (P &lt; 0.05) along riparian habitats, and SCE was found 73% higher at erosive than depositional habitats. SOC was found as a prominent regulator of SCE which alone explained about 80% of the variability in SCE. Moreover, soil moisture, fine particles, pH and MBC also showed strong control on SCE along riparian landscapes. Stepwise regression analysis revealed that after excluding SOC as a main variable, soil moisture explained 32% of the variability in SCE at overall landscape level whereas fine particles and MBC explained 78% and 23% of the variability in SCE at erosive and depositional habitats, respectively. Overall, results indicate that erosive habitats are the major source of SCE, and variation in biophysical variables is greatly affecting the SCE at these habitats. Therefore, further assessment of interactions of SCE, soil biophysical parameters and their regulatory components such as hydrology, vegetation and anthropogenic activities at micro—(site and land-use) as well as macro—(landscape) scales would help to understand the soil C dynamics along the heterogeneous riparian landscapes under climate change scenarios. © 2019, Springer Nature Switzerland AG.

Life Sciences

Aquatic Sciences

Geomorphologic heterogeneity influences dry-season soil CO2 efflux by mediating soil biophysical variables in a tropical river valley

Arsenic prevalence in the environment impelled many organisms to develop resistance over the course of evolution. Tolerance to arsenic, either as the pentavalent [As(V)] form or the trivalent form [As(III)], by bacteria has been well studied in prokaryotes, and the mechanism of action is well defined. However, in the rod-shaped arsenic tolerant Deinococcus indicus DR1, the key enzyme, arsenate reductase (ArsC) has not been well studied. ArsC of D. indicus belongs to the Grx-linked prokaryotic arsenate reductase family. While it shares homology with the well-studied ArsC of Escherichia coli having a catalytic cysteine (Cys 12) and arginine triad (Arg 60, 94, and 107), the active site of D.indicus ArsC contains four residues Glu 9, Asp 53, Arg 86, and Glu 100, and with complete absence of structurally equivalent residue for crucial Cys 12. Here, we report that the mechanism of action of ArsC of D. indicus is different as a result of convergent evolution and most likely able to detoxify As(V) using a mix of positively- and negatively-charged residues in its active site, unlike the residues of E. coli. This suggests toward the possibility of an alternative mechanism of As (V) degradation in bacteria. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

Journal of Molecular Modeling

Structure and function prediction of arsenate reductase from Deinococcus indicus DR1

Nuclear receptors (NRs) are transcription factors that bind to specific DNA sequences known as hormone response elements located upstream of their target genes. Transcriptional activity of NRs can be modulated by binding of the compatible ligand and transient interaction with cellular coregulators, functioning either as coactivators or as corepressors. Many coactivator proteins possess intrinsic histone acetyltransferase (HAT) activity that catalyzes the acetylation of specific lysine residues in histone tails and loosens the histone-DNA interaction, thereby facilitating access of transcriptional factors to the regulatory sequences of the DNA. Tat interactive protein 60 (TIP60), a member of the Mof-Ybf2-Sas2-TIP60 family of HAT protein, is a multifunctional coregulator that controls a number of physiological processes including apoptosis, DNA damage repair, and transcriptional regulation. Over the last two decades or so, TIP60 has been extensively studied for its role as NR coregulator, controlling various aspect of steroid receptor functions. The aim of this review is to summarize the findings on the role of TIP60 as a coregulator for different classes of NRs and its overall functional implications. We also discuss the latest studies linking TIP60 to NR-associated metabolic disorders and cancers for its potential use as a therapeutic drug target in future. Copyright © 2018 Endocrine Society.

Endocrinology

Modulation of Nuclear Receptor Function by Chromatin Modifying Factor TIP60

Carbohybrids are an important class of molecules which exhibit diverse biological activities and are present as structural motifs in many natural products. Two series of new triazole linked N-glycosides of coumarins and quinolones (n = 27) were efficiently synthesized starting from 1-azido-2,3,4,6-tetra-O-acetyl β-d-glucose and 1-azido-2,3,4,6-tetra-O-acetyl β-d-galactose reacting with various 4-O-propargyl coumarins and 4-O-propargyl quinolones in shorter reaction time (30 min) under microwave assisted conditions. Anticancer activity of these newly synthesized triazole linked N-glycosides of coumarins and quinolones was determined in detail through cellular assays against MCF-7 (breast cancer cell line), HepG2 (liver cancer cell line), HCT-116 (colon cancer cell line) and Huh-7.5 cell lines. The selected library member displayed low micromolar (IC50 10.97 μM) and selective toxicity against the breast cancer cell line (MCF-7). Mechanistic studies showed that the anticancer activity of the active compound was because of the generation of reactive oxygen species (ROS). This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

New Journal of Chemistry

Synthesis of new triazole linked carbohybrids with ROS-mediated toxicity in breast cancer

Partial Differential Equations for Mathematical Physicists is intended for graduate students, researchers of theoretical physics and applied mathematics, and professionals who want to take a course in partial differential equations. This book offers the essentials of the subject with the prerequisite being only an elementary knowledge of introductory calculus, ordinary differential equations, and certain aspects of classical mechanics. We have stressed more the methodologies of partial differential equations and how they can be implemented as tools for extracting their solutions rather than dwelling on the foundational aspects. After covering some basic material, the book proceeds to focus mostly on the three main types of second order linear equations, namely those belonging to the elliptic, hyperbolic, and parabolic classes. For such equations a detailed treatment is given of the derivation of Green's functions, and of the roles of characteristics and techniques required in handling the solutions with the expected amount of rigor. In this regard we have discussed at length the method of separation variables, application of Green's function technique, and employment of Fourier and Laplace's transforms. Also collected in the appendices are some useful results from the Dirac delta function, Fourier transform, and Laplace transform meant to be used as supplementary materials to the text. A good number of problems is worked out and an equally large number of exercises has been appended at the end of each chapter keeping in mind the needs of the students. It is expected that this book will provide a systematic and unitary coverage of the basics of partial differential equations. Key Features. An adequate and substantive exposition of the subject. Covers a wide range of important topics. Maintains mathematical rigor throughout. Organizes materials in a self-contained way with each chapter ending with a summary. Contains a large number of worked out problems. © 2019 by Taylor & Francis Group, LLC. All Rights Reserved.

Partial Differential Equations for Mathematical Physicists

Partial differential equations for mathematical physicists

Two-dimensional (2D) group-VI transition metal dichalcogenide (TMD) semiconductors, such as MoS2, MoSe2, WS2 and others manifest strong light matter coupling and exhibit direct band gaps which lie in the visible and infrared spectral regimes. These properties make them potentially interesting candidates for applications in optics and optoelectronics. The excitons found in these materials are tightly bound and dominate the optical response, even at room temperatures. Large binding energies and unique exciton fine structure make these materials an ideal platform to study exciton behaviors in two-dimensional systems. This review article mainly focuses on studies of mechanisms that control dynamics of excitons in 2D systems-an area where there remains a lack of consensus in spite of extensive research. Firstly, we focus on the kinetics of dark and bright excitons based on a rate equation model and discuss on the role of previous 'unsuspected' dark excitons in controlling valley polarization. Intrinsically, dark and bright exciton energy splitting plays a key role in modulating the dynamics. In the second part, we review the excitation energy-dependent possible characteristic relaxation pathways of photoexcited carriers in monolayer and bilayer systems. In the third part, we review the extrinsic factors, in particular the defects that are so prevalent in single layer TMDs, affecting exciton dynamics, transport and non-radiative recombination such as exciton-exciton annihilation. Lastly, the optical response due to pump-induced changes in TMD monolayers have been reviewed using femtosecond pump-probe spectroscopy which facilitates the analysis of underlying physical process just after the excitation. This journal is © The Royal Society of Chemistry.

RSC Advances

Physics of excitons and their transport in two dimensional transition metal dichalcogenide semiconductors

The influences of naphthyl and/or phenyl rings at the 2,4-positions of the quinolinyl fragments in carbazole-quinoline conjugates are studied. The centric phase of one of the conjugates (β-CQNN) revealed both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), while prompt fluorescence and RTP were observed in the non-centric phase (α-CQNN) that can regenerate the emission features of β-CQNNvia mechanical grinding. This unique observation is explained by the modulation of the higher-lying triplet (T2) energy level caused by conformational change. © The Royal Society of Chemistry.

Chemical Communications

Thermally activated delayed fluorescence and room-temperature phosphorescence in naphthyl appended carbazole-quinoline conjugates, and their mechanical regulation