Existence and fractional regularity of solutions for a doubly nonlinear differential inclusion

This article considers the issues of existence and regularity of solutions to the following doubly nonlinear differential inclusion $$\omega_t+\alpha (\omega_t)-\Delta \omega-\Delta_p{\omega} \ni f$$ where α is a maximal monotone operator in ${\mathbb{R}^2}$ and Δ _p denotes the p-Laplacian with p > 2. The investigation on fractional regularity is based on the Galerkin method combined with a suitable basis for W ^1,p , which we exhibit as a preliminary result. This approach also allows the obtaining of estimates in the so-called Nikolskii spaces, since it balances the interplay between the maximal monotone operator with the appearing higher order nonlinear terms.     

Ternary analogues of Lie and Malcev algebras

We consider two analogues of associativity for ternary algebras: total and partial associativity. Using the corresponding ternary associators, we define ternary analogues of alternative and assosymmetric algebras. On any ternary algebra the alternating sum [a, b, c] = abc − acb − bac + bca + cab − cba (the ternary analogue of the Lie bracket) defines a structure of an anticommutative ternary algebra. We determine the polynomial identities of degree ?7 satisfied by this operation in totally and partially associative, alternative, and assosymmetric ternary algebras. These identities define varieties of ternary algebras which can be regarded as ternary analogues of Lie and Malcev algebras. Our methods involve computational linear algebra based on the representation theory of the symmetric group.     

Stereoselective synthesis of the 6,6-spiroketal core of CP-61,405 (routiennocin)

A convergent and efficient synthesis of the 6,6-spiroketal core of the ionophore antibiotic CP-61,405 (routiennocin) is described. The synthesis required 10 steps from N-propionyl oxazolidinone (S)-8 and produced the desired spiroketal in 36% overall yield.     

Solvent extraction studies of phosphonium salts and their analytical applications : Detection of gold. identification of gold and minor constituents in gold alloys

Gold is very efficiently extracted with benzene or toluene after precipitation in acidic solution by excess thiocyanate and triphenylisopropyl phosphonium ions. An almost specific test for gold is thus possible and large amounts of gold can be separated from other elements. A scheme of separation is described for the identification of gold and other metal components in gold alloys, based on selective extraction of the triphenylisopropyl phosphonium salts of the corresponding thiocyanato complexes.     

Construction and evaluation of a flow injection micro-analyser based on urethane-acrylate resin

A flow injection micro-analyser with an integrated injection device and photometric detection is described. Channels measuring 205-295 μm depth by 265-290 μm maximum width were manufactured by deep UV lithography on two layers of urethane-acrylate oligomers-based photoresist. Hypodermic syringe needles (450 μm diameter) were connected to the channels for introduction of solutions into the system. Plastic optical fibres were connected to the ends of a 5.0 mm long channel, in order to conduct the light from and to a homemade photometer. The device has a total volume of 7.0 μL and three different sample volumes (0.09, 0.22 and 0.30 μL) can be inserted into the system by choosing the appropriate loop of the hydrodynamic injection approach. The micro-analyser, designed as a single line manifold, was evaluated by determining chloride in waters (mercuric thiocyanate method), and chromium (VI) in wastewater and total chromium in metallic alloys (diphenylcarbazide method). For chloride determination two micro-pumps were employed to impel the solutions, while for chromium determination this task was performed by a conventional peristaltic pump. The results obtained in all determinations did not differ significantly from the reference methods at a confidence level of 95%. In the chloride determination, a flow rate of 50 μL min⁻¹ was used, providing a sample frequency of 45 injection h⁻¹, generating ca. 0.7 mg of Hg(II) after an 8-h working day (ca. 20 mL of solution). This result suggests the potential of the micro-analyser towards the reduction of waste, following the philosophy of Green Chemistry.     

TWO WATER-SOLUBLE FLUORESCENCE PROBES FOR CHEMIEXCITATION STUDIES: SODIUM 9,10-DIBROMO- AND 9, 10-DIPHENYLANTHRACENE-2-SULFONATE. SYNTHESIS, PROPERTIES AND APPLICATION TO TRIPLET ACETONE AND TETRAMETHYLDIOXETANE

The syntheses of sodium 9,10-dibromo- and 9,10-diphenylanthracene-2-sulfonate (DBAS and DPAS, respectively) are described and their photophysical properties determined. These two probes were used in aqueous solution studies of the kinetic parameters of tetramethyldioxetane thermolysis, which were found to be the same as in organic solvents. The yields of triplet and singlet acetone generated by the decomposition of this dioxetane in water are also comparable to the literature values in organic medium. The lifetime of triplet acetone in water was determined to be 13 ± 2 u.s by a method based on the measurement of the fluorescence decay of DBAS excited via energy transfer from triplet acetone, by the time-correlated single-photon counting technique. Sorbate ion quenches triplet acetone from tetramethyldioxetane with a rate constant smaller but close to the diffusion-controlled limit.     

Quantitative analysis by comprehensive two-dimensional gas chromatography using interval Multi-way Partial Least Squares calibration

A new approach for target quantitative analysis for comprehensive two-dimensional gas chromatography (GC × GC), interval Multi-way Partial Least Square (iNPLS) is presented and evaluated in this paper. In iNPLS, the two-dimensional chromatogram is split in small sections; each of these pieces is treated as an independent new chromatogram. Separated conventional NPLS calibration models for the concentration of the target analyte are built for each of the pieces of the whole chromatogram, and the best model is selected for quantitative analysis. An algorithm for iNPLS running on MatLab platform was written, preliminarily evaluated with using solutions of model compounds with different chemical properties and subsequently applied to quantify some allergens in perfume samples. The results were found to be adequate, and good precision and accuracy was obtained even for poorly resolved peaks.     

Intraspecific variation in the essential oils from Drimys brasiliensis leaves and stem barks

The essential oils from leaves and stem barks of Drimys brasiliensis Miers (Winteraceae), collected in July and December 2008, were analyzed by GC/FID and GC/MS. The stem bark oils were composed mainly of monoterpenes (July, 45 +/- 3%; December, 92 +/- 4%), while the oils from leaves showed the predominance of sesquiterpenes (July, 47 +/- 1%; December, 55 +/- 1%). The variation in the relative amount of constituents could be associated, at least in part, to several microclimatic parameters such as precipitation, temperature and/or phenological state, which were different for each collection of D. brasiliensis.     

A comparative study of the non-isothermal degradation of natural rubber from Mangabeira (Hancornia speciosa Gomes) and Seringueira (Hevea brasiliensis)

Due to the increasing search for alternative sources of natural rubber (NR) whose properties are similar to Hevea brasiliesis, several sources have been studied in the past few years. Among them, Mangabeira (Hancornia speciosa Gomes), which is native to Amazon rainforest and other regions of Brazil, has a potential as another viable rubber source. As a continuation of a series of comparative studies between Hancornia and Hevea (clone RRIM 600) these two species by our research team, their thermal behavior was analyzed by thermogravimetry (TG) using Flynn–Wall–Ozawa’s approach in order to obtain kinetic parameters (reaction order, pre-exponential factor and activation energy) of the decomposition process. Results indicated that the thermal behavior of NR from Hancornia was comparable to Hevea with some differences observed as follows: reaction order for Hancornia was higher than for Hevea at the beginning of degradation and very close for temperatures over 350 °C; activation energy and pre-exponential factor had the same trend, i.e., increased with increasing degree of conversion remaining almost constant between 20 and 70% and then increasing for higher degrees, although Hevea was slightly more thermally stable than Hancornia. These major influences in the degradation process in the early stage are attributed to differences in non-rubber constituents present in these two species.     

Enhancement of Antibiotic Activity by 1,8-Naphthyridine Derivatives against Multi-Resistant Bacterial Strains

The search for new antibacterial agents has become urgent due to the exponential growth of bacterial resistance to antibiotics. Nitrogen-containing heterocycles such as 1,8-naphthyridine derivatives have been shown to have excellent antimicrobial properties. Therefore, the purpose of this study was to evaluate the antibacterial and antibiotic-modulating activities of 1,8-naphthyridine derivatives against multi-resistant bacterial strains. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of the following compounds: 7-acetamido-1,8-naphthyridin-4(1H)-one and 3-trifluoromethyl-N-(5-chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide. The antibiotic-modulating activity was analyzed using subinhibitory concentrations (MIC/8) of these compounds in combination with norfloxacin, ofloxacin, and lomefloxacin. Multi-resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were used in both tests. Although the compounds had no direct antibacterial activity (MIC ≥ 1.024 µg/mL), they could decrease the MIC of these fluoroquinolones, indicating synergism was obtained from the association of the compounds. These results suggest the existence of a structure–activity relationship in this group of compounds with regard to the modulation of antibiotic activity. Therefore, we conclude that 1,8-naphthyridine derivatives potentiate the activity of fluoroquinolone antibiotics against multi-resistant bacterial strains, and thereby interesting candidates for the development of drugs against bacterial infections caused by multidrug resistant strains.