Silver-nanoparticle immobilized initiator and co-initiators for free radical polymerization

The specific properties of silver-nanoparticle immobilized initiator and co-initiators for free radical polymerization were studied. The silver-nanoparticle immobilized benzophenone photoinitiates the free radical polymerization in both UV and visible regions. The photoinitiation ability of Bp-MPCs in visible region suggests a possible two-photon action even at low intensity of an incident light. The co-initiation process by MA-MPCs is more efficient in comparison to the co-initiation observed for corresponding free mercaptoamino acid. This behavior can be attributed to: (i) specific interaction of sulfur electron with surface plasmon electrons that make an electron transfer from mercaptoamino acid to excited electron acceptor more efficient, or (ii) to a locally higher concentration of electron donor (in the ligand shell) in comparison to classical a single-phase solution.     

The pH influence on photocatalytic decomposition of organic dyes over A11 and P25 titanium dioxide

The photocatalytic removal (decomposition+adsorption) of four azodyes (Reactive Red 198, Acid Black 1, Acid Blue 7 and Direct Green 99) in water was investigated using Tytanpol A11 (“Police” Chemical Factory, Poland) and Degussa P25 (“Degussa”, Germany) as photocatalysts. The effect of pH of the reaction solution has been examined. The degree of the dye removal in the solution was measured by UV-Vis spectroscopy. Photodecomposition of dye on photocatalyst surface was monitored by FTIR spectroscopy. A11 photocatalyst has lower activity in the reaction of photocatalytic decomposition of organic dyes than Degussa P25. The photocatalytic decomposition of the dyes takes place on the photocatalyst surface at pH=2 while at pH=12 photocatalytic reaction proceeds via photogenerated hydroxyl radicals for both A11 and P25.     

The interaction of lactic acid–glass cements with aqueous solutions

Cylindrical specimens of experimental lactic acid–glass cements (6 mm high×4 mm diameter) were prepared, matured at 37 °C for one week sealed in their molds, then exposed either to water (pH 6.6) or aqueous lactic acid (pH 2.7) for a further week. Solutions were analyzed by ICP-OES and their pH values recorded. In both solutions, cement specimens were found to release aluminum together with smaller amounts of calcium, sodium, silicon and phosphorus. They also formed soft gels that ICP-OES analysis showed were comprised mainly of aluminum and phosphorus species. These dissolution and gelation processes were accompanied by changes in the pH of the storage media (water to pH 4.9; lactic acid to 4.2). It is concluded that further work is necessary in order to fully characterize the species of aluminum released from these cements.     

DFT Studies of Selected Epoxies with Mesogenic Units–Impact of Molecular Structure on Electro-Optical Response

Theoretical studies of molecular structure and electric charge distribution were carried out for three epoxy compounds with different mesogenic cores. The compounds exhibit a nematic phase and form polymer networks that are potential bases for various composites. Results were compared to analogous materials with non-polar chains. A customized process involving geometry optimization of a series of conformations was employed to greatly increase likelihood of reaching global energy minimum for each molecule. All computations used Density Functional Theory (DFT) electron correlation model with the B3LYP hybrid functional. Molecular structure calculations yielded several parameters, including the magnitude and direction of the dipole moment, polarizability (α), first hyperpolarizability (β), and highest-occupied/lowest-unoccupied molecular orbital (HOMO-LUMO) energies. These parameters can help predict electronic properties of the nematic phase and the polymer network and assess their predisposition for application in electrooptical devices. In particular, the magnitude and direction of the dipole moment determine molecular alignment of liquid crystal phases in electric field, which enables controlling molecular order also in cured networks. Theoretical results were supplemented with observations of the nematics and their behavior in electric field. It was demonstrated for the studied compounds that a change in aliphatic chain polarity helps preserve and reinforce perpendicular alignment of molecules induced by electric field.     

Thermal properties of titin from porcine and bovine muscles

The thermal properties of titin isolated from porcine and bovine longissimus muscles were investigated by differential scanning calorimetry in the temperature range from 20 to 100?°C. A single peak with average maximum temperatures of 75.6 and 78.4?°C characterized porcine and bovine titin denaturation, respectively. The peaks were much broader than those from the other major muscle proteins. Titin denaturation enthalpy values (1.6-2.6 J/g) were only about half those of whole meat and also lower than those previously determined for myosin, actin, or collagen. The relatively high titin denaturation temperature suggests that it may be partially responsible for meat toughening when muscle tissue is heated above 60?°C.     

The effect of leaf protein concentrate from red clover on plasma cholesterol level in rats

The effect of native and defatted leaf protein concentrate (LPC) from red clover on plasma cholesterol level in rats was studied. Fat-free casein was used as a control protein. The native LPC contained 212 g kg^?1 of ether extract and oleic acid (C_{18: 1}) was its main fatty acid. LPC protein was relatively poor in sulphur-containing amino acids. Each protein studied was given to rats with or without soya bean oil. It was found that total cholesterol level in plasma of rats fed with the oil-containing diets was higher than that of rats fed with the oil-free diets. Original fat present in the native LPC though rich in unsaturated fatty acids had no hypocholesterolaemic effect. LPC was hypocholesterolaemic compared with casein in diets not containing added soya bean oil, although the difference did not reach statistical significance.     

Genetic characterization of the CcpA-dependent, cellobiose-specific PTS system comprising CelB, PtcB and PtcA that transports lactose in Lactococcus lactis IL1403

Lactose metabolism is one of the most important areas of research on Lactic Acid Bacteria (LAB). In rapidly acidifying industrial Lactococcus lactis strains, lactose is transported by a lactose-specific phosphotransferase system (PTS) encoded by a plasmid. However, an alternative lactose catabolic pathway was evidenced in the plasmid-cured, and thus initially lactose-negative L. lactis IL1403. We showed that in this strain the chromosomally-encoded cellobiose-specific PTS system comprising the celB, ptcB and ptcA genes is also able to transport lactose. By expression studies in the wild type IL1403 strain and IBB550, its ccpA-deficient derivative, we demonstrated that celB, ptcB and ptcA are tightly regulated by the general catabolite repression system, whereas celB additionally requires the presence of cellobiose to be fully induced. The comparison of expression levels of sugar catabolic genes indicated that the efficiency of CcpA-mediated catabolic repression depends on conservation of the cre sequence, and that in the case of perfect matching with the cre consensus, CcpA still drives a strong repression even under non-repressing conditions.     

A combinatorial genetic library approach to target heterologous glycosylation enzymes to the endoplasmic reticulum or the Golgi apparatus of Pichia pastoris

To humanize the glycosylation pathway in the yeast Pichia pastoris, we developed several combinatorial genetic libraries and used them to properly localize active eukaryotic mannosidases and sugar transferases. Here we report the details of the fusion of up to 66 N-terminal targeting sequences of fungal type II membrane proteins to 33 catalytic domains of heterologous glycosylation enzymes. We show that while it is difficult to predict which leader/catalytic domain will result in the desired activity, analysis of the fusion protein libraries allows for the selection of the leader/catalytic domain combinations that function properly. This combinatorial approach, together with a high-throughput screening protocol, has allowed us to humanize the yeast glycosylation pathway to secrete human glycoprotein with complex N-glycosylation.     

Understanding the effect of surface chemistry on charge generation and transport in poly (3-hexylthiophene)/CdSe hybrid solar cells

For hybrid solar cells, interfacial chemistry is one of the most critical factors for good device performance. We have demonstrated that the size of the surface ligands and the dispersion of nanoparticles in the solvent and in the polymer are important criteria in obtaining optimized device performance. The size of the ligands will affect the charge transport at the particle/particle and particle/polymer interfaces and the chemical structures of the ligands will determine their compatibility with the solvent and polymer. Hence other than pyridine, 2-thiophenemethylamine also showed good potential as ligand replacement for poly(3-hexylthiophene)/CdSe hybrid solar cells. With the right ligand combination, we have shown that the power conversion efficiency improved by a factor of 6 after ligand exchange.