<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

Biobased phenols and amines are attractive feedstock in rapid emerging polybenzoxazine thermosets. Renewable benzoxazines are mainly monofunctional due to structure limitation of raw materials, especially amines. Here, we report fully naturally sourced bifunctional benzoxazines by a simple one-step solventless microwave synthesis using cardanol/guaiacol- and carbohydrate-based isomannide diamine (ima). Chirality of ima led to complicated 1H NMR spectra of monomers. Heteronuclear single-quantum coherence (HSQC) and two-dimensional correlated spectroscopy (COSY) NMR and single-crystal X-ray diffraction confirmed the structure and formation of monomers. Polymerization and thermal stability of monomers and polymers were found to be either better than or comparable to widely studied fully and partly petro-based polybenzoxazines. Incorporation of rigid core ima in fully biobased polybenzoxazines showed a glass-transition temperature comparable to their petro-based aromatic diamine counterparts. Exploration of adhesive behavior revealed that the designed polybenzoxazine framework showed 2-fold higher lap shear strength than bisphenol-A (BPA) aniline polybenzoxazine. The current work highlights the utility of higher functionality renewable amines as promising candidates to design future high-performance fully biobased BPA-free polybenzoxazines. Copyright © 2019 American Chemical Society.

Chemistry

ACS Sustainable Chemistry and Engineering

Isomannide-Derived Chiral Rigid Fully Biobased Polybenzoxazines

Isobutyraldehyde underwent auto-oxidation in the presence of molecular oxygen to generate an acyloxy radical under a "metal-free" environment. They were subsequently exploited in situ to afford hypervalent iodines with p-anisolyl iodide which generated substituted 1,3,4-oxadiazoles in moderate to excellent yields from N′-arylidene acetohydrazides. The reaction strategy tolerated diverse substitution on the hydrazide substrates. Control experiments and literature precedence supported the formation of an in situ iodosylarene complex that facilitates the formation of products. © 2019 American Chemical Society.

World University root node

Organic Letters

Harnessing Autoxidation of Aldehydes: In Situ Iodoarene Catalyzed Synthesis of Substituted 1,3,4-Oxadiazole, in the Presence of Molecular Oxygen

An aromatic oligoamide sequence composed of a light-responsive diazaanthracene-based aromatic $\beta$-sheet flanked by two variable diameter helical segments was prepared. Structural investigations revealed that such oligomers adopt two distinct conformations: a canonical symmetrical conformation with the two helices stacked above and below the sheet and an unanticipated unsymmetrical conformation in which one helix has flipped to directly stack with the first helix. Photoirradiation of the foldamer led to the quantitative and thermally reversible, formation of a single photoproduct resulting from the [4+4] cycloaddition of two diazaanthracenes within the aromatic $\beta$-sheet. NMR and crystallographic studies revealed a parallel arrangement of the diazaanthracene photoproduct and a complete conversion into a symmetrical conformation requiring a rearrangement of all unsymmetrical conformers. These results highlight the potential of foldamers, with structures more complex than isolated helices, for the design of photoswitches showing nontrivial nanometer scale shape changes.

Fulltext

Angewandte Chemie - International Edition

Light-Controlled Conformational Switch of an Aromatic Oligoamide Foldamer

A cyclotomic polynomial φk(x) is an essential cyclotomic factor of f (x) ∈ Z[x] if φk(x) ∥ f (x) and every prime divisor of k is less than or equal to the number of terms of f: We show that if a monic polynomial with coefficients from {-1, 0, 1} has a cyclotomic factor, then it has an essential cyclotomic factor. We use this result to prove a conjecture posed by Mercer ['Newman polynomials, reducibility, and roots on the unit circle', Integers 12(4) (2012), 503-519]. © 2019 Australian Mathematical Publishing Association Inc.

Mathematics

Bulletin of the Australian Mathematical Society

Cyclotomic factors of borwein polynomials

In the present study, an ionic liquid (IL), known as green solvent, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) with four carbons in the hydrophobic chain (C-4) has been used as an additive to modify the self-assembled aggregates of an anionic surfactant sodium dodecyl sulfate (SDS) and then the evolution of the liquid crystalline phases has been investigated. Small angle synchrotron x-ray diffraction study has revealed an unprecedented phase sequence where a hexagonal phase (HI) of direct cylindrical micelles is observed to evolve to another hexagonal phase (HII) of, again, direct cylindrical micelles with a lamellar phase (Lα) as the intermediate. The rheological data and the theoretical calculations have confirmed the phases. To understand such a phase behaviour of the system, the work is extended by considering the ionic liquids with the same head group but of shorter (C-2) and longer (C-10) hydrocarbon chains compared to BMIM-BF4. While the shorter chain IL causes the hexagonal phase to form rectangular (R) phase, the longer chain is observed to induce the lamellar phase (Lα). The molecular mechanism of appearance of such different phases has been discussed. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

Physics

Liquid Crystals

Re-entrant direct hexagonal phases in a lyotropic system of surfactant induced by an ionic liquid

Communicable diseases are leading cause of child mortality in developing and under-developed countries. Public health ministries in states and country allocate a considerable amount of budget every year for vaccination campaigns to control infections. Even third-party agencies such as Gates Foundation, UNDP, GAVI, World Bank, WHO also allocate huge funds to under-developed and developing countries for vaccination programs and disease eliminations. However, economic constraints and current disease prevalence are not enough driving factors for optimal decisions in budget allocations for vaccinations and controlling the disease. In a population under voluntary vaccination campaign, high vaccine coverage cannot be taken for granted, as individuals’ free-riding behaviour plays a significant role in achieving the herd immunity level coverage. Individual-level vaccine exemptions and ignoring this important component by the policymakers are key determinants for failure of disease elimination program these days in many under-developed and developing countries. We integrate evolutionary game theory and compartmental model of disease transmission to analyze how individual vaccination choice influence the budget allocations and vice-versa. Our model illustrates that individuals’ perceived risk plays an important role in optimal budget allocations to minimize infections. Analyses of our model indicate that the optimal distribution of third-party funds may be very different than usual, especially in multiple populations with contrasting demographic and economic profiles. These findings are certainly useful to public health policymakers and may help to quantify certain parameters in budget allocations to control vaccine-preventable diseases. © 2019 Elsevier Ltd

Journal of Theoretical Biology

Game dynamic model of optimal budget allocation under individual vaccination choice

In this article, we compile the work done by various mathematicians on the topic of the fixed divisor of a polynomial. This article explains most of the results concisely and is intended to be an exhaustive survey. We present the results on fixed divisors in various algebraic settings as well as the applications of fixed divisors to various algebraic and number theoretic problems. The work is presented in an orderly fashion so as to start from the simplest case of Z, progressively leading up to the case of Dedekind domains. We also ask a few open questions according to their context, which may give impetus to the reader to work further in this direction. We describe various bounds for fixed divisors as well as the connection of fixed divisors with different notions in the ring of integervalued polynomials. Finally, we suggest how the generalization of the ring of integer-valued polynomials in the case of the ring of n × n matrices over Z (or a Dedekind domain) could lead to the generalization of fixed divisors in that setting. © 2019, Institut Camille Jordan. All rights reserved.

Electrical Engineering

(SoE) School of Engineering

Confluentes Mathematici

A survey on fixed divisors

A clear understanding of the surface chemical reactivity of tungsten (W) films is indispensable for photocatalytic, sensing and memory applications, especially in the presence of WO x (0 ≤ x ≤ 3) for low thicknesses. Here, surface reactivity of the film through diffusion of oxygen and its ability to make bonds with W is identified by X-ray photoelectron spectroscopy (XPS). Further inspection of XPS valence band spectra confirms the possible hybridization of W 5d and O 2p electrons in the presence of defect states near Fermi level. Exploration of surface morphology by scanning electron microscopy (SEM) reveals agglomeration of grains with increasing film thickness. Detailed microstructural and grazing-incidence X-ray diffraction (GIXRD) studies suggest the formation of β W nanocrystallites in amorphous matrix, and establish a knowledge of thickness dependent phase transformation of W beside surface oxidation. The nonlinear surface current–voltage characteristics at low thickness further indicates dimensional phase change owing to the involvement of point defects. We also report a detailed study of interstitial and vacancy mediated diffusion probability of oxygen in W films, where the estimated diffusion constant is found to be relatively higher than that of other body-centered cubic transition metals. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Electronics

Probing the impact of surface reactivity on charge transport in dimensional phase changed tungsten films

This paper presents a plasma display device (PDD) based on laser-induced graphene nanoribbons (LIGNs), which were directly fabricated on polyimide sheets. Superior field electron emission (FEE) characteristics, viz. a low turn-on field of 0.44 V/µm and a large field enhancement factor of 4578, were achieved for the LIGNs. Utilizing LIGNs as a cathode in a PDD showed excellent plasma illumination characteristics with a prolonged plasma lifetime stability. Moreover, the LIGN cathodes were directly laser-patternable. Such superior plasma illumination performance of LIGN-based PDDs has the potential to make a significant impact on display technology. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

Nanomaterials

Laser-patternable graphene field emitters for plasma displays

Novel experimental and sequencing techniques have led to an exponential explosion and spiraling of data in viral genomics. To analyse such data, rapidly gain information, and transform this information to knowledge, interdisciplinary approaches involving several different types of expertise are necessary. Machine learning has been in the forefront of providing models with increasing accuracy due to development of newer paradigms with strong fundamental bases. Support Vector Machines (SVM) is one such robust tool, based rigorously on statistical learning theory. SVM provides very high quality and robust solutions to classification and regression problems. Several studies in virology employ high performance tools including SVM for identification of potentially important gene and protein functions. This is mainly due to the highly beneficial aspects of SVM. In this chapter we briefly provide lucid and easy to understand details of SVM algorithms along with applications in virology. © Springer Nature Switzerland AG 2019. All rights reserved.