Examples of almost Einstein structures on products and in cohomogeneity one

Almost Einstein manifolds are conformally Einstein up to a scale singularity, in general. This notion comes from conformal tractor calculus. In the current paper we discuss almost Einstein structures on closed Riemannian product manifolds and on 4-manifolds of cohomogeneity one. Explicit solutions are found by solving ordinary differential equations. In particular, we construct three families of closed 4-manifolds with almost Einstein structure corresponding to the boundary data of certain unimodular Lie groups. Two of these families are Bach-flat, but neither (globally) conformally Einstein nor half conformally flat. On products with a 2-sphere we find an exotic family of almost Einstein structures with hypersurface singularity as well.     

A Neumann problem for the KdV equation with Landau damping on a half-line

We consider the initial-boundary value problem on a half-line for the KdV equation with Landau damping. We study traditionally important problems of the theory of nonlinear partial differential equations, such as global in time existence of solutions to the initial-boundary value problem and the asymptotic behavior of solutions for large time.     

Chemical constituents of the methanolic extract of leaves of Leiothrix spiralis Ruhland and their antimicrobial activity

Chemical fractionation of the methanolic extract of leaves of Leiothrix spiralis Ruhland afforded the flavonoids luteolin-6-C-β-D-glucopyranoside (1), 7-methoxyluteolin-6-C-β-D-glucopyranoside (2), 7-methoxyluteolin-8-C-β-D-glucopyranoside (3), 4'-methoxyluteolin-6-C-β-D-glucopyranoside (4), and 6-hydroxy-7-methoxyluteolin (5), and the xanthones 8-carboxymethyl-1,5,6-trihydroxy-3-methoxyxanthone (6), 8-carboxy-methyl-1,3,5,6-tetrahydroxyxanthone (7). Methanolic extract, fractions, and isolated compounds of the leaves of L. spiralis were assayed against Gram-positive (Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella setubal and Helicobacter pylori) and fungi (the yeasts Candida albicans, C. tropicalis, C. krusei and C. parapsilosis). We observed the best minimum inhibitory concentration values for the methanolic extract against Candida parapsilosis, for the fraction 5 + 6 against Gram-negative bacteria E. coli and P. aeruginosa, and compound 7 against all tested Candida strains. The methanolic extract contents suggest that this species may be a promising source of compounds to produce natural phytomedicines.     

On a Class of Solutions to the Generalized Derivative Schrödinger Equations

In this work we shall consider the initial value problem associated to the generalized derivative Schrödinger (gDNLS) equations and Following the argument introduced by Cazenave and Naumkin we shall establish the local well-posedness for a class of small data in an appropriate weighted Sobolev space. The other main tools in the proof include the homogeneous and inhomogeneous versions of the Kato smoothing effect for the linear Schrödinger equation established by Kenig-Ponce-Vega.     

Solid luminescent CdSe‐thiolated porous phosphate heterostructures. Application in fingermark detection in different surfaces

A fluorescent hybrid material (PPH‐S‐CdSe), which comprises cadmium selenide sulphide nanoparticles assembled onto thiol functionalised porous phosphate heterostructures (PPH‐SH), was synthesised in aqueous media. This material presents a high stability towards photo‐degradation. The obtained nanocomposite was characterised by various techniques such as Fourier transform infrared spectroscopy, energy dispersive X‐ray, transmission electron microscopy (TEM), X‐ray diffraction, X‐ray photoelectron spectroscopy and fluorescence spectroscopy. This fluorescent material showed a red emission at 576 nm combined with other at 473 nm, explained as different CdS_0.42Se_0.58 nanoparticles size, supported by TEM images. It was suitable for latent fingermark analysis in a wide range of surfaces. Because of its sensitivity and low cost, it is an actual alternative to conventional powdering materials. Copyright © 2012 John Wiley & Sons, Ltd.     

The structure of azines derived from C‐formyl‐1H‐imidazoles in solution and in the solid state: tautomerism,configurational and conformational studies

The structures of three azines derived from 2‐formylimidazole, 4(5)‐formylimidazole, and 4(5)‐formyl‐5(4)‐methylimidazole have been determined in solution and in the solid state. Density Functional Theory (DFT) Polarizable Continuum Model (PCM) calculations (geometries, energies, and chemical shifts), NMR [solution and cross polarization magic‐angle spinning (CPMAS)], and X‐ray crystallography [azine of 4(5)‐formylimidazole] have been used. The configuration around the central C = N bonds has been determined and some insights about prototropic tautomerism and conformation have been gained. Copyright © 2013 John Wiley & Sons, Ltd.     

CdS Quantum Dots Nanoparticles Dispersed in Zeolites. Optical Study

Synthesis, characterization, and the optical behavior of CdS quantum dots nanoparticles, confined in zeolites, following a new synthesis approach in different natural zeolites mordenite, clinoptilolite, and syntheticZSM-5, were carried out. The composite materials are characterized by x-ray diffraction, Fourier transmission infrared spectroscopy, energy dispersive, scanning and transmission electron microscopy. After CdS-QDs formation, the synthesized materials become fluorescent with emission wavelengths (average and standard deviation of the maximum wavelength; full width of half maximum): Mordenite-CdS QDs (628 ± 5 nm; 272 nm); clinoptilolite-CdS QDs (585 ± 8 nm; 284 nm), and ZSM-5-CdS QDs (579 ± 4 nm; 214 nm). [Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.]     

Optical Characterization of CdS Quantum Dots Nanoparticles Dispersed in Clays

Synthesis, characterization, and the optical behavior of CdS quantum dots nanoparticles were studied confined in clays. An alternative synthesis approach in different natural clays K-10 bentonite, Na-montemorillonite, halloysite, and saponite was carried out. The composite materials were characterized by XRD and FTIR spectroscopy, energy dispersive, scanning, and transmission electron microscopy. After CdS-QDs formation, the synthesized materials became fluorescent with emission wavelengths (average and standard deviation of the maximum wavelength; full width of half maximum): K-10 bentonite-CdS (590 ± 5 nm; 183 nm); Na-montmorillonite-CdS (550 ± 3 nm; 219 nm); saponite-CdS (550 ± 5 nm; 219 nm), and halloysite-CdS (590 ± 8 nm; 185 nm). (Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.)     

Interfacial behavior of OEG-linear dendron monolayers: aggregation, nanostructuring, and electropolymerizability

We report on the interesting interfacial behavior of oligoethylene glycol or OEGylated linear dendron monolayers at the air-water interface as a function of (a) carbazole dendron generation, (b) the length of the OEG units, and (c) the surface pressure applied upon compression. Surface pressure-area isotherms, hysteresis studies, and isobaric creep measurement revealed a structure-property relationship consistent with the hydrophilic-lipophilic balance of a linear dendron with the OEG group serving as the surface anchor to the water subphase. AFM studies revealed that all the OEGylated carbazole dendrons self-assemble into spherical morphology at low surface pressures but form ribbonlike structures as the surface pressure is increased. This nanostructuring is primarily imparted by the increase in van der Waals forces with increasing amount of carbazole units per dendron generation on a hydrophilic mica surface. Further, electrochemical cross-linking of the carbazole molecules by cyclic voltammetery (CV) on doped Si wafer has enabled the formation of an LB film monolayer with a secondary level of organization in the monolayer imparted by the inter- and intramolecular cross-linking among the carbazole units. This study should provide a basis for monolayer film materials based on combining the LB technique and electrochemical cross-linking for nanostructuring superstructures at the air-water interface.