Generating near-bipartite bricks

Carvalho, Lucchesi and Murty (2006, How to build a brick, Discrete Math., 306, 2383-2410) gave a generation procedure for bricks. In particular, they showed that every brick may be constructed from , the triangular prism , and the Petersen graph. The object of this paper is to establish a generation procedure that is specific to the class of near-bipartite bricks. In particular, we show that every near-bipartite brick may be constructed from and so that each intermediate brick is also near-bipartite. Norine and Thomas (2007, Generating bricks, J. Combin. Theory Ser. B, 97, 769-817) proved a generation theorem for simple bricks. In a subsequent work with Marcelo H. de Carvalho (2017, Generating simple near-bipartite bricks, https://arxiv.org/abs/1704.08796 ), we use the results of this paper to prove a generation theorem for simple near-bipartite bricks.     

Patterned Hydrophilization of Nanoporous 1,2‐PB by Thiol‐ene Photochemistry

We present an efficient method for functionalizing the large polymer–air interface of a gyroid nanoporous polymer. The hydrophilicity of nanoporous cross‐linked 1,2‐polybutadiene is tuned by thiol‐ene photo‐grafting of mercaptosuccinic acid or sodium 2‐mercaptoethanesulfonate. The reaction is monitored by FT‐IR, UV–Vis, contact angle, and gravimetry. Overall quantum yields are calculated for the two thiol‐ene “click” reactions in nano‐confinement, neatly revealing their chain‐like nature. Top–down photolithographic patterning is demonstrated, realizing hydrophilic nanoporous “corridors” exclusively hosting water. The presented approach can be relevant for many applications where, e.g., high control and contrast in hydrophilicity, chemical functionality or refractive index are needed.

     

Third and fourth order invariants for one-dimensional time-dependent classical systems

The construction of invariants up to fourth order in velocities has been carried out for one-dimensional, time-dependent classical dynamical systems. While the exact results are recovered for the first and second order integrable systems, the results for the third and fourth order invariants are expressed in terms of nonlinearpotential equations. Noticing the separability of the potential in space and time variables these nonlinear equations are reduced to a tractable form. A possible solution for the third order case suggests a new integrable systemV(q, t) ∼t ^−4/3 q ^1/2. Alexander von Humboldt-Stiftung Fellow, on leave from the Department of Physics, Ramjas College (University of Delhi), Delhi 110 007, India.     

Construction of Exact Invariants for Time Dependent Classical Dynamical Systems

In the present work, we survey various methodsused for the construction of exact invariants fordynamical systems involving an explicit time dependence.More stress is placed on two-dimensional (2D) than one-dimensional (1D) systems. While bothharmonic and anharmonic time-dependent (TD) systems arediscussed in the 1D case, the construction of invariantsis carried out for several interesting central and noncentral systems in 2D. The method ofcomplexification of two space dimensions is described indetail. The TD coupled oscillator problem, which in analternative form suggests the generalization of Ermakov systems, is analyzed in greater detail. Theavailable methods in the 2D case provide only the firstinvariant, and that for a few TD systems. These methodsas such are still inadequate as far as the construction of the second invariant is concerned. The roleand scope of some of the derived invariants in thecontext of various physical problems are highlighted.The possibility of extension of some of these methods to 3D TD systems is also discussed.     

Synthesis of some novel divalent transition metal complexes as antimicrobials

A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H- 1,2,4-triazol-4-ylamino)melhyl)quinolm-8-ol with transition metal salts.The structures of these compounds have been elucidated by elemental and spectral analysis.Furthermore,compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus.The various compounds show potent inhibitory action against test organisms.     

Ground-to-Satellite Optical Communication Link Performance with Spatial Diversity in Weak Atmospheric Turbulence

Abstract

In this article, performance improvement of a free-space optical communication link with spatial diversity is evaluated for coherent (sub-carrier BPSK and sub-carrier QPSK) and non-coherent (OOK and Q-PPM) modulation schemes in an atmospheric turbulence fading channel. Based on Kolmogorov's theory, the link performance characterized by the signal-to-noise ratio or bit error rate is evaluated for both modulation schemes. It is observed that there is performance improvement with the increase in the order of transmit diversity for all the modulation schemes. Sub-carrier BPSK modulation outperforms the other modulation schemes in terms of the minimum signal-to-noise ratio requirement for a given bit error rate. Also, the effect of correlation among different transmitting antenna beams on the link performance is analyzed.     

Chemoenzymatic synthesis and high-throughput screening of an aminoglycoside-polyamine library: identification of high-affinity displacers and DNA-binding ligands

Chemoenzymatic parallel synthesis and high-throughput screening were employed to develop a multivalent aminoglycoside-polyamine library for use as high-affinity cation-exchange displacers and DNA-binding ligands. Regioselective lipase-catalyzed acylation, followed by chemical aminolysis, was used to generate vinyl carbonate and vinyl carbamate linkers, respectively, of the aminoglycosidic cores. These were further derivatized with polyamines, leading to library generation. A parallel batch-displacement assay was employed to identify the efficacy of the library candidates as potential displacers for protein purification. Using this approach, low-molecular-mass displacers with affinities higher than those previously observed have been identified. The aminoglycoside-polyamine library was also screened for DNA binding efficacy using an ethidium bromide displacement assay. These highly cationic molecules exhibited strong DNA-binding properties and may have potential for enhanced gene delivery.     

Spectrophotometric determination of quercetin with VO2+

Summary The coloured complex formed on reaction of quercetin (3,3, 4, 5,7-pentahydroxyflavone) with vanadyl sulphate is used as the basis for a sensitive and reproducible spectrophotometric method for estimation of quercetin. The 11 complex exhibits maximum absorption at 425 nm in aqueous ethanol (80% v/v) adjusted to pH 3.3. Beer's law is followed over the quercetin concentration range of 0.3–20 g/ml. The molar absorptivity is 1.4×10⁴ l·mole^–1·cm^–1. This method can be used for the determination of quercetin isolated from biological sources. In the metal complex, the 4-carbonyl and 3-hydroxy groups of the quercetin are involved.

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Zusammenfassung Der bei der Umsetzung von Quercetin (3,3, 4, 5,7-Pentahydroxyflavon) mit Vanadylsulfat entstehende gefärbte Komplex wurde als Grundlage für eine empfindliche und reproduzierbare spektrophotometrische Bestimmung von Quercetin verwendet. Die maximale Absorption dieses 11-Komplexes beträgt in wäßrigem Äthanol (80% v/v) bei pH 3,3 und 425 nm. Bei Quercetin-Konzentrationen zwischen 0,3 und 20 g/ml gilt das Beersche Gesetz. Der molare Extinktionskoeffizient beträgt 1,4·10⁴ l· mol^–1·cm^–1. Das Verfahren kann zur Quercetinbestimmung nach Isolierung aus biologischem Material verwendet werden. An der Komplexbildung ist die 4-Carbonyl- und die 3-Hydroxygruppe des Quercetins beteiligt.

     

In vitro anticancer and antibacterial activities of octahedral ruthenium(III) complexes with hydroxamic acids. Synthesis and spectroscopic characterization

Five new ruthenium(III) complexes of the general formulas [RuCl(H₂O)L₂] (1–4) and [RuCl₃(H₂O)(HL)₂] (5), where L = benzohydroximato (1), salicylhydroximato (2), acetohydroximato (3), hydroxyureato (4), LH = N-hydroxy-N-phenylbenzamide (5), were synthesized by reaction of RuCl₃ · 3H₂O with the corresponding hydroxamic acids at a molar ratio of 1: 2 molar. The complexes were characterized by elemental analyses and FT-IR, UV-Vis, ¹H and ¹³C NMR, and mass spectra. The complexes showed higher antibacterial activity against ten pathogenic bacterial strains than the corresponding ligands. The anticancer activity of the complexes against IMR-32 (neuroblastoma) cancer and CHO (Chinese hamster ovary) normal cell lines was evaluated using MTT assay with respect to camptothecin as control. Complex 5 was found to exhibit an appreciable cytotoxicity against IMR-32 cell line with an IC₅₀ value of 102.27 μM.