H2S Promoted Oxidative Dehydrogenation of Hydrocarbons in Molten Media

The H₂S promoted oxidative dehydrogenation of butane to butadiene can be efficiently carried out if a molten salt medium, e.g. LiCl/KCl, is used to dissipate the heat from the highly exothermic reaction. The reaction is catalyzed by the addition of soluble salts such at Tl₂O₃, BaCl₂ or MnCl₂. Optimization of reaction conditions by varying temperature, space velocity and quantity of promoter results in a 53% olefin yield (5% butenes, 48% butadiene) at 80% butane conversion. The system is also shown to be efficient for the dehydrogenation of ethane to ethylene, propane to propylene, butene to butadiene and ethylbenzene to styrene.     

SO2 promoted oxidative dehydrogenation of ethylbenzene

It has been demonstrated that SO₂ acts as an efficient dehydrogenation agent in the conversion of ethylbenzene to styrene in the presence of alkali and alkaline earth metal oxide doped alumina and titania catalysts. Development of these catalysts, which give styrene yields of greater than 80% per pass, is described in the paper. The catalysts allow the use of close to stoichiometric amounts of sulphur dioxide, are active in the presence of steam diluent and show low deactivation with time. The effect of varying process conditions such as temperature, reactant concentration and diluent amount is also described.     

Syngonanthus nitens Bong. (Rhul.)-Loaded Nanostructured System for Vulvovaginal Candidiasis Treatment

Herbal-loaded drug delivery nanotechnological systems have been extensively studied recently. The antimicrobial activity of medicinal plants has shown better pharmacological action when such plants are loaded into a drug delivery system than when they are not loaded. Syngonanthus nitens Bong. (Rhul.) belongs to the Eriocaulaceae family and presents antiulcerogenic, antioxidant, antibacterial, and antifungal activity. The aim of this study was to evaluate the antifungal activity of Syngonanthus nitens (S. nitens) extract that was not loaded (E) or loaded (SE) into a liquid crystal precursor system (S) for the treatment of vulvovaginal candidiasis (VVC) with Candida albicans. The minimal inhibitory concentration (MIC) was determined by the microdilution technique. Additionally, we performed hyphae inhibition and biofilm tests. Finally, experimental candidiasis was evaluated in in vivo models with Wistar female rats. The results showed effective antifungal activity after incorporation into S for all strains tested, with MICs ranging from 31.2 to 62.5 μg/mL. Microscopic observation of SE revealed an absence of filamentous cells 24 h of exposure to a concentration of 31.2 μg/mL. E demonstrated no effective action against biofilms, though SE showed inhibition against biofilms of all strains. In the in vivo experiment, SE was effective in the treatment of infection after only two days of treatment and was more effective than E and amphotericin B. The S. nitens is active against Candida albicans (C. albicans) and the antifungal potential is being enhanced after incorporation into liquid crystal precursor systems (LCPS). These findings represent a promising application of SE in the treatment of VVC.     

Multigrid Methods on Semi-Structured Grids

In this work, efficient block-wise multigrid solvers on semi-structured triangular grids are presented for two-dimensional problems. They take advantage of the flexibility of triangular grids as well as the efficiency of block-structured grids, yielding very promising solvers on nowadays hardware. Semi-structured grids offer many advantages for the stencil-wise implementation of geometric multigrid, as well as for an efficient implementation of finite element methods without assembling the global matrix. The semi-structured character of the grids enables us to develop the multigrid algorithm on a block-wise manner, by choosing different components on the structured patches of the mesh. In order to select appropriate components for the different grid geometries of the blocks, a?local Fourier analysis is presented as a very useful tool. Finally, the practical utility of this approach is demonstrated with some numerical experiments.     

Effect of pressing speed and specific pressure in pressure mould cavity on values of mechanical properties of aluminium cast of lower weight category made from EN AC 47100 alloy

The requirements on the quality of aluminium alloy casts analogically increase with the rising interest in their use mainly in automobile industry. The casts are becoming more and more complex in shape and with the tendency of decreasing the thickness of their walls, and the requirements on their mechanical properties, porosity and impermeability are increasing. The submitted paper deals with the effect of pressing speed and specific pressure in pressure mould cavity on the quality of a cast, which is represented by permanent deformation s and porosity f. In another contribution, the casting defects, which cause lower values of mechanical properties, are determined. In this paper, the causes of the occurrence of these errors are denominated, and requirements on their elimination are determined from metallographic cuts obtained from the SEM based on the type of errors and their identification.     

VOC exposures in California early childhood education environments

Little information exists about exposures to volatile organic compounds (VOCs) in early childhood education (ECE) environments. We measured 38 VOCs in single‐day air samples collected in 2010‐2011 from 34 ECE facilities serving California children and evaluated potential health risks. We also examined unknown peaks in the GC/MS chromatographs for indoor samples and identified 119 of these compounds using mass spectral libraries. VOCs found in cleaning and personal care products had the highest indoor concentrations (d‐limonene and decamethylcyclopentasiloxane [D5] medians: 33.1 and 51.4 μg/m³, respectively). If reflective of long‐term averages, child exposures to benzene, chloroform, ethylbenzene, and naphthalene exceeded age‐adjusted “safe harbor levels” based on California's Proposition 65 guidelines (10^?5 lifetime cancer risk) in 71%, 38%, 56%, and 97% of facilities, respectively. For VOCs without health benchmarks, we used information from toxicological databases and quantitative structure–activity relationship models to assess potential health concerns and identified 12 VOCs that warrant additional evaluation, including a number of terpenes and fragrance compounds. While VOC levels in ECE facilities resemble those in school and home environments, mitigation strategies are warranted to reduce exposures. More research is needed to identify sources and health risks of many VOCs and to support outreach to improve air quality in ECE facilities.     

Optical characterization of ZnO

The green (2.19 eV) and yellow (2.00 eV) luminescence bands in ZnO polycrystalline samples were studied by photoluminescence, excitation luminescence, time-resolved spectroscopy and lifetime measurements. A shift towards higher energies of the green emission band is observed for temperatures above 35 K indicating that at least two excited levels 74 meV apart are involved in the recombination process.     

Is ionic dialysance useful for early detection of vascular access dysfunction? Six illustrative cases

Continuous ionic dialysance monitoring is a useful clinical tool to determine the dialysis dose in real time in each hemodialysis session. We followed up 49 patients for 16 months. Six patients with a Kt reduction of ≥20% in >3 consecutive hemodialysis sessions were identified. Fistulography demonstrated significant stenosis in all 6 patients. Angioplasty was performed in 5 with an excellent angiographic result and optimal Kt levels were restored. Unexplained and persistent Kt reduction in patients with stable chronic kidney disease under hemodialysis could represent, together with an accurate vascular access examination, a practical and additional indirect method for the early detection of vascular access dysfunction.