An a Posteriori Error Estimate for a Semi-Lagrangian Scheme for Hamilton–Jacobi Equations

We present an a posteriori estimate for a first order semi-Lagrangian method for Hamilton–Jacobi equations. The result requires piecewise C ^1,1 regularity of the viscosity solution and is stated for the Bellman equation related to the infinite horizon problem, although it can be applied to more general Hamilton–Jacobi equations with convex Hamiltonians. This estimate suggests different numerical indicators that can be used to construct an adaptive algorithm for the approximation of the viscosity solution.     

Synthesis of a New Series of Imidazo[1,5- d ]pyrido[2,3- b ][1,4]thiazines as Potential Ligands for the GABA Receptor Complex

 Starting from 2-chloro-3-nitropyridine, 1H-pyrido[2,3-b][1,4]thiazin-2(3H)-one was synthesized. This compound was reacted with potassium tert-butoxide and diethyl chlorophosphate to give the intermediate 1H-pyrido[2,3-b][1,4]thiazin-2-ylphosphate derivative, which in turn afforded the 1,2,4-oxadiazolylimidazo[1,5-d]pyrido[2,3-b]pyrazine derivatives. The title compounds are potential ligands for the γ-aminobutyric acid A/benzodiazepine receptor complex.     

Electrochemical oxidation of bentazon at a glassy carbon electrode Application to the determination of a commercial herbicide

The electrochemical methods cyclic, differential pulse and square wave voltammetry were applied to develop an electroanalytical procedure for the determination of the herbicide bentazon in a commercial product, containing bentazon as the active ingredient, used to treat rice and corn crops. The oxidation mechanism is complex, consisting of an electrochemical step followed by chemical dimerization reaction of the products, which causes severe adsorption problems and consequent poisoning of the electrode surface. The effect of adding Triton surfactant is to enable determinations with good reproducibility to be carried out; the analytical conditions were studied and optimized. The limit of detection obtained was 10(-5) M.     

Essential Oil from Eucalyptus globulus (Labill.) Activates Complement Receptor-Mediated Phagocytosis and Stimulates Podosome Formation in Human Monocyte-Derived Macrophages

Eucalyptus essential oil and its major constituent eucalyptol are extensively employed in the cosmetic, food, and pharmaceutical industries and their clinical use has recently expanded worldwide as an adjuvant in the treatment of infective and inflammatory diseases. We previously demonstrated that essential oil from Eucalyptus globulus (Labill.) (EO) stimulates in vitro the phagocytic activity of human monocyte-derived macrophages and counteracts the myelotoxicity induced by the chemotherapeutic 5-fluorouracil in immunocompetent rats. Here we characterize some mechanistic aspects underlying the immunostimulatory ability exerted by EO on macrophages. The internalization of fluorescent beads, fluorescent zymosan BioParticles, or apoptotic cancer cells was evaluated by confocal microscopy. Pro-inflammatory cytokine and chemokine release was determined by flow cytometry using the BD cytometric bead array. Receptor involvement in EO-stimulated phagocytosis was assessed using complement- or IgG-opsonized zymosan particles. The localization and expression of podosome components was analyzed by confocal microscopy and western blot. The main results demonstrated that: EO-induced activation of a macrophage is ascribable to its major component eucalyptol, as recently demonstrated for other cells of innate immunity; EO implements pathogen internalization and clearance by stimulating the complement receptor-mediated phagocytosis; EO stimulates podosome formation and increases the expression of podosome components. These results confirm that EO extract is a potent activator of innate cell-mediated immunity and thereby increase the scientific evidence supporting an additional property of this plant extract besides the known antiseptic and anti-inflammatory properties.     

Surface plasmons for fluorescence enhancement in Sm-doped borate glasses

Heat treatment of Sm-activated lithium and sodium borate glasses which are additionally doped with silver oxide leads to a reduction of the doped silver ions and to the formation of metallic silver nanoparticles indicated by a broad plasmon-related absorption band in the visible spectral range. The influence of the plasmon resonance field enhancement on the Sm³⁺ fluorescence excitation bands is too small to lead to enhanced fluorescence emission intensities.     

C–H···π and C=O···π Intermolecular Interactions in Dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate

Abstract A new pyrazine compound, has been synthesised and characterised by single-crystal X-ray diffraction: monoclinic, P2₁/c with a = 11.0707(3) ?, b = 5.23700(10) ?, c = 16.6997(5) ?, β = 103.5385(16)°, Mr = 376.40, V = 941.30(4) ?³, Z = 2. Each molecule possesses C _i symmetry with the two halves of the molecule related by an inversion centre. C–H···π and C=O···π interactions held the molecules together. Index Abstract C–H···π and C=O···π intermolecular interactions in dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate Joana A. Silva, Ana C. Santos, Ana T. Marques, Manuela Ramos Silva, Ana Matos Beja, Abílio J. F. N. Sobrala In dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate, each molecule possesses C _i symmetry. The molecules are assembled in chains via carbonyl···π interactions. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

New-chitosan characterization and its bioassay in different salinity solutions using <Emphasis Type="Italic">Artemia salina</Emphasis> as bio tester

New chitosan powder extracted from eggs capsules of Rapana venosa and commercial chitosan powder were analyzed by spectral (UV–Vis) and color methods. The novelty of this study consists in the first time toxicity evaluation of the chitosan extracted from the walls of Rapana venosa eggs capsules. The evaluation was focused on the cytological behaviour of the new-chitosan particles in two different salinity conditions (3 and 35‰), at different concentrations, on bio tester organisms. The aim of this study was to determine the biological effect of the chitosan easily extracted from new marine sources and with a low financial effort. The experimental studies were performed by exposure of Artemia salina larvae, naupliar stage in saline chitosan solutions. The larvae were picked-up in 24 h time, after hatching and they were placed in the experimental recipients of 1 mL volume capacities, three repetitions were made for each test. The bioassay effects were recorded at 24 and 48 h after experiment started. The toxicity was indicated by the registration of larvae mortality, probably, induced by the cell growth inhibitions. The obtained results showed that the high toxicity effects could be observed at low concentrations of chitosan, in law salinity solutions. Due to this cytotoxicity variability, chitosan solutions could be useful in a wide range of applications (antifouling, biomedical or sewage cleaning).     

Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection

Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.     

Chemistry of diazafulvenium methides in the synthesis of functionalized pyrazoles

The chemistry of diazafulvenium methides generated by the thermal extrusion of sulfur dioxide from 2,2-dioxo-1H,3H-pyrazolo[1,5-c] [1,3]thiazoles is described. The diazafulvenium methides unsubstituted at C-7 participate in [8 pi + 2 pi] cycloadditions giving pyrazolo-annulated heterocycles resulting from the addition across the 1,7-position. 1-Methyl-diazafulvenium methides and 7,7-dimethyl-diazafulvenium methides undergo intramolecular sigmatropic [1,8]H shifts giving vinyl-1H-pyrazoles.     

Synthesis and characterization of new thienylpyrrolyl-benzothiazoles as efficient and thermally stable nonlinear optical chromophores

The synthesis and full characterization of new chromophores with second-order nonlinearities containing thienylpyrrolyl and benzothiazolyl moieties are reported. The solvatochromic behavior of the compounds was investigated. The hyperpolarizabilities β of derivatives 4-6 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that strong nonlinearity is balanced by good thermal stability especially for chromophores 6b and 6c, making them good candidates for NLO applications.