Conversion efficiency of glucose/xylose mixtures for ethanol production using Saccharomyces cerevisiae ITV01 and Pichia stipitis NRRL Y‐7124

BACKGROUND: Efficient conversion of glucose/xylose mixtures from lignocellulose is necessary for commercially viable ethanol production. Oxygen and carbon sources are of paramount importance for ethanol yield. The aim of this work was to evaluate different glucose/xylose mixtures for ethanol production using S. cerevisiae ITV‐01 (wild type yeast) and P. stipitis NRRL Y‐7124 and the effect of supplying oxygen in separate and co‐culture processes. RESULTS: The complete conversion of a glucose/xylose mixture (75/30 g L^?1) was obtained using P. stipitis NRRL Y‐7124 under aerobic conditions (0.6 vvm), the highest yield production being Y_p/s = 0.46 g g^?1, volumetric ethanol productivity Q_pmax = 0.24 g L^?1 h^?1 and maximum ethanol concentration P_max = 34.5 g L^?1. In the co‐culture process and under aerobic conditions, incomplete conversion of glucose/xylose mixture was observed (20.4% residual xylose), with a maximum ethanol production of 30.3 g L^?1, ethanol yield of 0.4 g g^?1 and Q_pmax = 1.26 g L^?1 h^?1. CONCLUSIONS: The oxygen present in the glucose/xylose mixture promotes complete sugar consumption by P. stipitis NRRL Y‐7124 resulting in ethanol production. However, in co‐culture with S. cerevisiae ITV‐01 under aerobic conditions, incomplete fermentation occurs that could be caused by oxygen limitation and ethanol inhibition by P. stipitis NRRL Y‐7124; nevertheless the volumetric ethanol productivity increases fivefold compared with separate culture. Copyright © 2011 Society of Chemical Industry     

Rhodium(I) complex catalyst immobilized on terpolymers of N‐vinylpyrrolidinone and 1‐vinylimidazole

The hydrosilylation of cyclohexanone and acetone with triethysilane and diphenysilane catalyzed by polymer‐supported Rh(I) complex has been investigated. Two terpolymers of styrene, divinylbenzene, and 1‐vinylimidazole (S/DVB/VI) or N‐vinylpyrrolidinone (S/DVB/NVP) were used as the catalysts supports. Physical characterization of these materials has involved the measurements of the structural parameters in the dry and swollen states by DSC, the nitrogen BET adsorption method and inverse steric exclusion chromatography ISEC. From these results it can be concluded that the original polymer structure has been changed during the complex attachment giving rise to materials of higher porosity. X‐ray photoelectron spectroscopy XPS, IR, and AAS spectroscopy were used to characterization of heterogeneous complexes before and after use. The effect of the morphology of the support on the catalytic properties of the polymer‐supported Rh(I) species was tested in the hydrosilylation of ketones and correlated with the reaction mechanism. It was demonstrated that the high selectivity of homogeneous rhodium complex toward the silyl ethers can be partially reversed to the dehydrogenative silylation products by a proper choice of polymer support with favorable microporous structure. Recycling tests demonstrated high stability of the supported catalysts during prolonged use. The constant selectivity of the supported catalysts demonstrated during recycling experiments showed that they could be useful for practical application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Relaxation processes and intermolecular interactions in PVME hydrogels in sub-zero temperatures: Glass transition and pre-melting of ice

The phase transition observed by various methods in poly(vinyl methyl ether)/water systems at around 18 °C has been assigned by some investigators to the pre-melting of water and by others to a glass transition of the polymer. In this study, broadband dielectric spectroscopy and temperature modulated differential scanning calorimetry were used to identify this transition in radiationally crosslinked poly(vinyl methyl ether) hydrogels, as well as to analyse sub-zero relaxation processes in such a three-phase (polymer/ice/liquid water) system. The process at 18 °C was related to the pre-melting of water induced by the segmental motions of the polymer; however, it was seen to be one transition due to the cooperative motions of both compounds. The atypical (two regimes) temperature dependence of the segmental motion process was observed and was related to confinement of the polymer chains between ice clusters below approximately ?24 °C; furthermore, the main dielectric process of hexagonal ice was identified and a Maxwell-Wagner effect was observed.     

A Stochastic Petri Net-Based Model of the Involvement of Interleukin 18 in Atherosclerosis

Interleukin 18 (IL-18) is a proinflammatory and proatherogenic cytokine with pleiotropic properties, which is involved in T and NK cell maturation and the synthesis of other inflammatory cytokines and cell adhesion molecules. It plays a significant role in orchestrating the cytokine cascade, accelerates atherosclerosis and influences plaque vulnerability. To investigate the influence of IL-18 cytokine on atherosclerosis development, a stochastic Petri net model was built and then analyzed. First, MCT-sets and t-clusters were generated, then knockout and simulation-based analysis was conducted. The application of systems approach that was used in this research enabled an in-depth analysis of the studied phenomenon. Our results gave us better insight into the studied phenomenon and allow revealing that activation of macrophages by the classical pathway and IL-18-MyD88 signaling axis is crucial for the modeled process.     

New 1,3,4-Oxadiazole Derivatives of Pyridothiazine-1,1-Dioxide with Anti-Inflammatory Activity

Numerous studies have confirmed the coexistence of oxidative stress and inflammatory processes. Long-term inflammation and oxidative stress may significantly affect the initiation of the neoplastic transformation process. Here, we describe the synthesis of a new series of Mannich base-type hybrid compounds containing an arylpiperazine residue, 1,3,4-oxadiazole ring, and pyridothiazine-1,1-dioxide core. The synthesis was carried out with the hope that the hybridization of different pharmacophoric molecules would result in a synergistic effect on their anti-inflammatory activity, especially the ability to inhibit cyclooxygenase. The obtained compounds were investigated in terms of their potencies to inhibit cyclooxygenase COX-1 and COX-2 enzymes with the use of the colorimetric inhibitor screening assay. Their antioxidant and cytotoxic effect on normal human dermal fibroblasts (NHDF) was also studied. Strong COX-2 inhibitory activity was observed after the use of TG6 and, especially, TG4. The TG11 compound, as well as reference meloxicam, turned out to be a preferential COX-2 inhibitor. TG12 was, in turn, a non-selective COX inhibitor. A molecular docking study was performed to understand the binding interaction of compounds at the active site of cyclooxygenases.     

Coupling of N2O Decomposition and Ethylbenzene Dehydrogenation over γ-Al2O3-Supported Transition Metal Oxide Catalysts

Transition metal (Cr, Cu, Fe, Co and Ni) oxides supported on -alumina were characterized with respect to their textural parameters and reducibility and used as catalysts in decomposition of nitrous oxide and ethylbenzene (EB) dehydrogenation as well as coupling of both processes. High activity of -Al₂O₃ in N₂O decomposition coupled with EB dehydrogenation has been found. An increase in EB and N₂O conversion was observed when transition-metal-containing catalysts were used. The activity of catalysts depended on their reducibility. Maximum N₂O efficiency was observed for the Cr/-Al₂O₃ sample, whereas -Al₂O₃-supported Cu and Fe oxide systems showed about 50% efficiency of N₂O in the reaction. An influence of the molar ratio of N₂O/EB on activity and selectivity of the catalysts was found. An excess of N₂O resulted in an increase in CO₂ formation at nearly constant styrene yield.     

Bubble Formation at a Rotating Cylindrical Surface in Cross‐Flowing Liquid

A novel method of gas sparging from a rotating cylinder is proposed, which prevents against formation of large attached gas cavities in cross‐flowing liquids including those flowing downwards. Experimental and theoretical results regarding critical rotation speed necessary to remove the attached cavity, bubble formation process and size distribution of the produced bubbles in a low viscosity system (air‐water) are presented in this study.     

Polyhydroxyalkanoate‐based drug delivery systems

Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA‐based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini‐review presents some recent scientific developments in the preparation of functionalized PHAs, PHA–drug and PHA–protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications. © 2016 Society of Chemical Industry