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Shiv Nadar University

(SoNS) School of Natural Sciences

World University root node

Physics

arXiv preprint arXiv:1807.10540

Comment on" Structure Prediction of Li-Sn and Li-Sb Intermetallics for Lithium-Ion Batteries Anodes''

Despite recent advances in polybenzoxazines (PBzs), especially of sustainable origin, the lowering of the curing temperature still remains a challenge in addressing their exploration in low-temperature processing applications. Innovative iron-based catalysts which are naturally abundant, cost-effective, and with larger surface area could demonstrate a practical, economic and facile approach for the development of iron NPs-polybenzoxazine composites. Here we propose an approach to develop a composite based on smartly-capped iron nanoparticles (NPs) and agro-waste phenolic-sourced cardanol benzoxazine monomer as a one-step solution with the benefits of lowering the curing temperature and providing superparamagnetism. NPs are smartly designed with a variation in the nature of the functionality in the capping agent and are characterized by thermogravimetry analysis (TGA), Fourier transform infrared (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The NPs showed a spherical shape of ∼10 nm in size with appreciable magnetic characteristics. Both iron ions and available functionalities in the capping agent endow benefits in lowering the curing temperature of cardanol benzoxazine (64 °C), and enhancing its maximum thermal stability (34 °C), as determined by differential scanning calorimetry (DSC) and TGA, respectively. In addition, the nature of the chemical linkages in the polybenzoxazine network and the initial growth in the molecular weight of the polymer were found to be influenced by iron NPs, as supported by FTIR, nuclear magnetic resonance (1H-NMR), UV-visible (UV-vis) spectroscopy, and gel permeation chromatography (GPC). The capping-agent-facilitated NPs distribution in the polybenzoxazine matrix was determined by atomic force microscopy (AFM). Polymer nanocomposites even with a 5 wt\% loading of NPs showed good magnetic saturation and superparamagnetic behavior. The present work demonstrated a one-step solution with the incorporation of NPs in a benzoxazine monomer accounting for modification in the properties of polybenzoxazine composites with the benefits of magnetism. © 2018 The Royal Society of Chemistry.

Chemistry

Fulltext

Journal of Materials Chemistry A

Sustainable one-step strategy towards low temperature curable superparamagnetic composite based on smartly designed iron nanoparticles and cardanol benzoxazine

Reversibility between two concomitant polymorphs and their switching ability is demonstrated for the novel organic nonlinear optical (NLO) material Z-3-(3-methoxyphynyl)-2-(4-nitrophenyl)acrylonitrile. The appearances of their concomitant as well as exclusive polymorphic forms were discovered upon systematic crystallization experiments using various solvents. Determination of X-ray crystal structures confirmed that the polymorphs crystallize in centrosymmetric (P21/n) and non-centrosymmetric (Fdd2) space groups. A search using the Cambridge Structural Database revealed that there exist only 10 such polymorphic pairs. Reversible phase transitions and the switching ability between the polymorphs can be achieved via both heat and solvents as stimuli. Structural analysis confirmed that the polymorphs have two-dimensional similarity. Further, quantitative and qualitative analysis of interaction energies based on the UNI force field and energy frameworks indicate that they possess very similar energies, although the centrosymmetric form is slightly lower in energy. A comparably high value of second harmonic generation activity and the NLO properties as estimated based on gas-phase and in-crystal calculations suggest that the non-centrosymmetric form could be a potential NLO material. To the best of our knowledge, this study is the rarest of its kind to show the reversibility and switching ability between centrosymmetric and non-centrosymmetric polymorphic phases in an organic material, induced via both thermal and solvent stimuli. © 2017 American Chemical Society.

Crystal Growth and Design

Concomitance, Reversibility, and Switching Ability of Centrosymmetric and Non-Centrosymmetric Crystal Forms: Polymorphism in an Organic Nonlinear Optical Material

In recent years, a new theory of the evolution of microbes under normal and stressed conditions has emerged, mainly in reference with the development of fractals and of self-organized mapping (SOM) concepts. This theory has much improved our understanding of the growth pattern of microbes like bacteria which determine their dynamics of evolution. In the first part of this paper, the main ideas in the theory of microbial self-organization are outlined, and some remarkable features of the resulting growth patterns are presented. In the second part, we apply conceptual tools developed in the context of fractal geometry to the study of the scaling properties of the bacterial growth in context with SOM patterns. We observe that such growth patterns appear to be more complex than simple fractals, although in some cases a simple fractal framework may be adequate for their description. © 2018, Springer Nature Singapore Pte Ltd.

Mathematics

Advances in Intelligent Systems and Computing

Self-organized Bacterial Evolutionary Dynamics: Fractal Characteristics

The driving force for the electron transfer (ET) step in the catalytic cycle of cytochrome P450BM3 is investigated using three sets of 1 μs molecular dynamic simulations for the resting state of P450 in complex with the flavin (FMN) in the reductase domain. These sets involve the following: (i) substrate-free (SF), (ii) substrate (N-palmitoyl glycine, i.e., NPG)-bound (SB), and (iii) SB with the semiquinone radical anion (SQ-) of FMN. Starting from the X-ray structure of the SF heme domain, we observe that the α1-helix (of the reductase) and the C-helix (of the heme) undergo reorientation to a parallel orientation, which is the thermochemically stable form. The reorientation of the helices pushes away the FMN to a distance of 18.4 Å from the heme's center. When the substrate binds it causes the I-helix of the heme domain to kink and push the C-helix toward the α1-helix, thereby locking the latter two into a stabilized perpendicular conformation, wherein the FMN-heme distance is 12 Å. The distance drops further in the SQ- form, and upon QM/MM geometry optimization the two moieties approach 8.8 Å, which enhances the ET rate (by 104-106 fold) to the heme's Fe3+ ion. These motions are driven by hydrogen bond strengthening between the C- and the α1-helices. Finally, substrate binding leads to formation of an organized water chain connecting the FMN and heme moieties. The water channel assists the ET and couples it to the proton transfer steps that should activate O2 and create the oxo-iron active species. © 2017 American Chemical Society.

Journal of the American Chemical Society

Choreography of the Reductase and P450BM3 Domains Toward Electron Transfer Is Instigated by the Substrate

In this letter, we consider the minimum mean-square error receiver for the generalized frequency division multiplexing system (GFDM) over frequency selective fading channels. We derive an approximate probability density function for the signal-to-interference-plus-noise ratio. This expression allows us to obtain a new approximate, but rather accurate formulation for the bit error probability for a M-quadrature amplitude modulation scheme. Our results resort on the pivotal properties exhibited by eigenvalues of a circulant matrix. Since the entries of the channel matrix Hch are complex Gaussian distributed, and the eigenvalues are given as a weighted sum of its entries, the joint eigenvalue distribution is also Gaussian. Comparisons of the simulated and analytical results validate our formulation and allow a quick and efficient tool to compute the bit error rate for the GFDM system. © 1997-2012 IEEE.

IEEE Communications Letters

Bit error probability for MMSE receiver in GFDM systems

A novel library of C2-substituted tryptamines (based on diverse C2-aroyl/arylimino indoles and indole-diketopiperazine hybrids) possessing antimitotic properties were designed, synthesized and screened for their inhibitory activity against tubulin polymerization, and against proliferation of A549 lung cancer, HeLa cervical cancer, MCF7 breast cancer and HePG2 liver cancer cell lines. The design of molecules were inspired from known antimitotic compounds and natural products. The molecular docking of the designed compounds indicated that they bind to the colchicin binding site of tubulin. They were synthesized by a unique iodine catalysed oxidative ring opening reaction of 1-aryltetrahydro-β-carbolines. Among the compounds synthesized quite a few compounds induced cytotoxicity on the cancer cells by disrupting the tubulin polymerization. They were found to be non-toxic for healthy cells. Immuno Fluorescence study for the most active molecules (between ~6 μM concentration) against A549 and HeLa cells demonstrated complete disruption and shrinkage of the microtubule structures. These compounds also inhibited indoleamine-2, 3-dioxygenase with low micromolar IC50. © 2018 Elsevier B.V.

European Journal of Pharmaceutical Sciences

Design, synthesis and biological evaluation of a novel library of antimitotic C2-aroyl/arylimino tryptamine derivatives that are also potent inhibitors of indoleamine-2, 3-dioxygenase (IDO)

Multiple environmental stresses adversely affect plant growth and development. Plants under multiple stress condition trigger cascade of signals and show response unique to specific stress as well as shared responses, common to individual stresses. Here, we aim to identify common and unique genetic components during stress response mechanisms liable for cross-talk between stresses. Although drought and cold stress have been widely studied, insignificant information is available about how their combination affects plants. To that end, we performed meta-analysis and co-expression network comparison of drought and cold stress response in Arabidopsis thaliana by analyzing 390 microarray samples belonging to 29 microarray studies. We observed 6120 and 7079 DEGs (differentially expressed genes) under drought and cold stress respectively, using Rank Product methodology. Statistically, 28\% (2890) DEGs were found to be common in both the stresses (i.e.; drought and cold stress) with most of them having similar expression pattern. Further, gene ontology-based enrichment analysis have identified shared biological processes and molecular mechanisms such as—‘photosynthesis’, ‘respiratory burst’, ‘response to hormone’, ‘signal transduction’, ‘metabolic process’, ‘response to water deprivation’, which were affected under cold and drought stress. Forty three transcription factor families were found to be expressed under both the stress conditions. Primarily, WRKY, NAC, MYB, AP2/ERF and bZIP transcription factor family genes were highly enriched in all genes sets and were found to regulate 56\% of common genes expressed in drought and cold stress. Gene co-expression network analysis by WGCNA (weighted gene co-expression network analysis) revealed 21 and 16 highly inter-correlated gene modules with specific expression profiles under drought and cold stress respectively. Detection and analysis of gene modules shared between two stresses revealed the presence of four consensus gene modules. © 2018 Sharma et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Life Sciences

PLoS ONE

Comparative transcriptome meta-analysis of Arabidopsis thaliana under drought and cold stress

Development of new class of anti-malarial drugs is an essential requirement for the elimination of malaria. Bioactive components present in medicinal plants and their chemically modified derivatives could be a way forward towards the discovery of effective anti-malarial drugs. Herein, we describe a new class of compounds, 1,3-benzoxazine derivatives of pharmacologically active phytophenols eugenol (compound 3) and isoeugenol (compound 4) synthesised on the principles of green chemistry, as anti-malarials. Compound 4, showed highest anti-malarial activity with no cytotoxicity towards mammalian cells. Compound 4 induced alterations in the intracellular Na+ levels and mitochondrial depolarisation in intraerythrocytic Plasmodium falciparum leading to cell death. Knowing P-type cation ATPase PfATP4 is a regulator for sodium homeostasis, binding of compound 3, compound 4 and eugenol to PfATP4 was analysed by molecular docking studies. Compounds showed binding to the catalytic pocket of PfATP4, however compound 4 showed stronger binding due to the presence of propylene functionality, which corroborates its higher anti-malarial activity. Furthermore, anti-malarial half maximal effective concentration of compound 4 was reduced to 490 nM from 17.54 µM with nanomaterial graphene oxide. Altogether, this study presents anti-plasmodial potential of benzoxazine derivatives of phytophenols and establishes disruption of parasite sodium homeostasis as their mechanism of action. © 2018 Elsevier Ltd

Bioorganic and Medicinal Chemistry Letters

Benzoxazine derivatives of phytophenols show anti-plasmodial activity via sodium homeostasis disruption

Ionic liquids (ILs) have generated considerable attention recently because of their cytotoxicity and application as antibiotics. However, the mechanism of how they damage cell membranes is not currently well understood. In this paper, the antibacterial activities of two imidazolium-based ILs, namely 1-butyl- 3-methylimidazolium tetrafluroborate ([BMIM][BF4]) and 1-ethyl- 3-methylimidazolium tetrafluroborate ([EMIM][BF4]) have been investigated. The activity of [BMIM][BF4] on gram negative bacteria E. coli is observed to be stronger compared with the short chained [EMIM][BF4]. To explain this observation, the effects of these ILs on the self-assembled structures of model cellular membranes have been investigated. The in-plane elasticity of a monolayer formed at air-water interface by 1,2-dipalmitoyl- sn-glycero- 3-phosphocholine (DPPC) lipids was reduced in the presence of the ILs. The x-ray reflectivity studies on polymer supported lipid bilayer have shown the bilayer to shrink and correspondingly exhibit an increase in electron density. The presence of a certain mol\% of negatively charged lipid, 1,2-dipalmitoyl-rac-glycero-3-phospho-L-serine (DPPS), in DPPC mono- and bi-layers enhances the effect considerably. © 2018 Elsevier B.V.