Uniqueness and bifurcation for semilinear elliptic equations on closed surfaces

Motivated by a question recently posed by H. Brezis we provide uniqueness and bifurcation results for some semilinear elliptic equations on two dimensional closed surfaces with exponential nonlinearities.     

Synthesis and Biological Evaluation of Amidinourea Derivatives against Herpes Simplex Viruses

Current therapy against herpes simplex viruses (HSV) relies on the use of a few nucleoside antivirals such as acyclovir, famciclovir and valacyclovir. However, the current drugs are ineffective against latent and drug-resistant HSV infections. A series of amidinourea compounds, designed as analogues of the antiviral drug moroxydine, has been synthesized and evaluated as potential non-nucleoside anti-HSV agents. Three compounds showed micromolar activity against HSV-1 and low cytotoxicity, turning to be promising candidates for future optimization. Preliminary mode of action studies revealed that the new compounds act in an early stage of the HSV replication cycle, just after the viral attachment and the entry phase of the infection.     

Bent polyynes: ring geometry studied by Raman and IR spectroscopy

Infrared (IR) and Raman spectroscopy have been used to examine the vibrational characteristics of a series of three macrocyclic tetraynes in comparison with an acyclic analog. By changing the length of the alkyl tether of the macrocycles, varying degrees of bending of the tetrayne moiety can be achieved, and the joint use of IR and Raman spectroscopies provides an avenue to probe the impact of bending on the sp‐chain. The spectroscopic data show a general trend toward decreasing activation of Raman bands in the IR spectra, and vice versa, as bending of the polyyne chain is decreased. Density functional theory calculations provide a detailed rationalization of the experimental observations. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of a discontinuous galerkin method for heterogeneous diffusion problems with low‐regularity solutions

We study the convergence of the Symmetric Weighted Interior Penalty discontinuous Galerkin method for heterogeneous diffusion problems with low‐regularity solutions only belonging to W^{2, p} with p ∈ (1,2]. In 2d, we infer an optimal algebraic convergence rate. In any space dimension d, we achieve the same result for p > 2 d/( d + 2). We also prove convergence without algebraic rates for exact solutions only belonging to the energy space. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2012     

Networks of motifs from sequences of symbols

We introduce a method to convert an ensemble of sequences of symbols into a weighted directed network whose nodes are motifs, while the directed links and their weights are defined from statistically significant co-occurences of two motifs in the same sequence. The analysis of communities of networks of motifs is shown to be able to correlate sequences with functions in the human proteome database, to detect hot topics from online social dialogs, to characterize trajectories of dynamical systems, and it might find other useful applications to process large amounts of data in various fields.     

Radical reduction of aromatic azides to amines with tributylgermanium hydride

[reaction: see text] Aromatic azides are inert toward tributylgermanium hydride under thermal conditions in the absence and in the presence of a radical initiator but in the presence of catalytic amounts of benzenethiol undergo fast reaction, yielding reduced anilines and 2-germylated derivatives in high overall yields.     

Radiation Induced Double Grafting of Polybutadiene Olygomers and Styrene onto Silica: Characterization of the Materials and Mechanistic Studies

Ionizing radiations from a 60-Co source have been employed for inducing radical reactions finally leading to the grafting of unsaturated olygomers and vinyl monomers onto the surface and micropores of precipitated silica Zeosil 1165 (150–170 m²/g). The target was to obtain modified silica with enhanced polar compatibility with respect to polybutadiene and styrene-butadiene copolymers rubber matrices and suited to favour the formation of chemically bound rubber in a vulcanization process. The latter property was expected to follow from the characteristics of free radical reactivity arising from the unsaturations present in the organic coating. Three classes of modified silica have been prepared: A)silica coated with polybutadiene olygomers with M_n in the range 1000–5000 and having a different relative content of 1,4-cis, 1,4-trans and vinyl double bonds 1 ; B)Silica coated with polybutadiene olygomers further modified by subsequent grafting of styrene monomer. The type A samples were obtained by γ irradiation under vacuum of silica samples pre-impregnated with the oligomers in the dose range up to 30–200 kGy. Type B samples were obtained via three different steps as outlined in the scheme below: