Isomerization of Eugenol Under Ultrasound Activation Catalyzed by Alkali Modified Mesoporous NbMCM-41

The present paper discloses a new alternative method for the isomerization of eugenol to isoeugenol where mesoporous materials containing niobium are used as solid base catalysts, affording good yields of isomerized product and being environmentally friendly. Nb-containing MCM-41 mesoporous materials were modified with alkaline cations (Li, Na, K, Rb and Cs) and characterized by BET, FTIR, XRD, and UV–vis techniques. The prepared materials were tested in the isomerization of eugenol to isoeugenol by sonochemical and thermally-activated reactions. Li, Na, K, Rb, and Cs/NbMCM-41 catalysts are active catalyst for the preparation of isoeugenol, and selective to the trans-isomer. Rb/NbMCM-41 sample is the optimum catalysts for the reaction. This result is in accordance with the calculated basicity observed during the Knoevenagel probe reaction of basicity. Conversions around 90% are obtained when using Rb-NbMCM-41 catalysts, with 90% selectivity to trans-isoeugenol, under ultrasound activation. In contrast, conversion around 72% with 90% selectivity is attained under classical thermal activation. The catalysts were reused four times without a substantial decrease of activity.     

Effects of GaAs-spacer strain on vertical ordering of stacked InAs quantum dots in a GaAs matrix

Vertical ordering in stacked layers of InAs/GaAs quantum dots is currently the focus of scientific research because of its potential for optoelectronics applications. Transmission electron microscopy was applied to study InAs/GaAs stacked layers grown by molecular-beam-epitaxy with various thicknesses of GaAs spacer. Thickness dependencies of quantum dot size and their ordering were observed experimentally and, then, compared with the results of strain calculations based on the finite element method. The vertical ordering did occur when the thickness of the GaAs spacer was comparable with the dot height. The ordering was found to be associated with relatively large InAs dots on the first layer. Quantum dots tend to become larger in size and more regular in plane with increasing numbers of stacks. Our results suggest that the vertical ordering is not only affected by strain from the InAs dots on the lower layer, but by total strain configuration in the multi-stacked structure.     

The influence of ceramic additives on intumescence and thermal activity of epoxy coatings for steel

The article presents results of the research on the influence of graphite/kaolin and graphite/titanium oxide systems on thermal properties, intumescence degree and the integrity of the structure of intumescent protective films based on epoxy resins for steel. The TG/DTG/DSC analysis showed that graphite/kaolin system shifted the decomposition reaction of epoxy resin towards higher temperatures, even by about 30°C. Fire endurance tests and the SEM analysis confirmed these results because more thermally resistant (T_500°C reached after 37.5 min for 1.1 coating thickness), swollen (about 20 times) and homogeneous coatings were obtained. The presented results suggest that ceramic fire retardants can successfully cooperate with organic components in intumescent protective coatings for steel elements.     

Altered Elemental Distribution in Male Rat Brain Tissue as a Predictor of Glioblastoma Multiforme Growth—Studies Using SR-XRF Microscopy

Glioblastoma multiforme (GBM) is a particularly malignant primary brain tumor. Despite enormous advances in the surgical treatment of cancer, radio- and chemotherapy, the average survival of patients suffering from this cancer does not usually exceed several months. For obvious ethical reasons, the search and testing of the new drugs and therapies of GBM cannot be carried out on humans, and for this purpose, animal models of the disease are most often used. However, to assess the efficacy and safety of the therapy basing on these models, a deep knowledge of the pathological changes associated with tumor development in the animal brain is necessary. Therefore, as part of our study, the synchrotron radiation-based X-ray fluorescence microscopy was applied for multi-elemental micro-imaging of the rat brain in which glioblastoma develops. Elemental changes occurring in animals after the implantation of two human glioma cell lines as well as the cells taken directly from a patient suffering from GBM were compared. Both the extent and intensity of elemental changes strongly correlated with the regions of glioma growth. The obtained results showed that the observation of elemental anomalies accompanying tumor development within an animal’s brain might facilitate our understanding of the pathogenesis and progress of GBM and also determine potential biomarkers of its extension. The tumors appearing in a rat’s brain were characterized by an increased accumulation of Fe and Se, whilst the tissue directly surrounding the tumor presented a higher accumulation of Cu. Furthermore, the results of the study allow us to consider Se as a potential elemental marker of GBM progression.     

The Antibacterial Effect of PEGylated Carbosilane Dendrimers on P. aeruginosa Alone and in Combination with Phage-Derived Endolysin

The search for new microbicide compounds is of an urgent need, especially against difficult-to-eradicate biofilm-forming bacteria. One attractive option is the application of cationic multivalent dendrimers as antibacterials and also as carriers of active molecules. These compounds require an adequate hydrophilic/hydrophobic structural balance to maximize the effect. Herein, we evaluated the antimicrobial activity of cationic carbosilane (CBS) dendrimers unmodified or modified with polyethylene glycol (PEG) units, against planktonic and biofilm-forming P. aeruginosa culture. Our study revealed that the presence of PEG destabilized the hydrophilic/hydrophobic balance but reduced the antibacterial activity measured by microbiological cultivation methods, laser interferometry and fluorescence microscopy. On the other hand, the activity can be improved by the combination of the CBS dendrimers with endolysin, a bacteriophage-encoded peptidoglycan hydrolase. This enzyme applied in the absence of the cationic CBS dendrimers is ineffective against Gram-negative bacteria because of the protective outer membrane shield. However, the endolysin—CBS dendrimer mixture enables the penetration through the membrane and then deterioration of the peptidoglycan layer, providing a synergic antimicrobial effect.     

Lateral and vertical isolation by arsenic implantation into MOCVD-grown GaAs layers

We have demonstrated the formation of arsenic precipitates in GaAs using arsenic implantation and annealing. Electrical measurements show that very high resistivity (surface or buried) GaAs layers can be produced by this method. The arsenic-implanted materials are similar to GaAs:As buffer layers grown by low-temperature molecular beam epitaxy, which are used for eliminating backgating problems in GaAs circuits. Arsenic implantation is a nonepitaxial process which is compatible with current GaAs technology. Formation of insulating GaAs layers by this technique may improve the performance and packing density of GaAs integrated circuits, leading to advanced novel III–V compound-based technologies for high-speed and radiation-hard circuits.     

Ordering in InGaAs/InAlAs layers

The structure of InCaAs/InAlAs layers lattice matched to an InP substrate, grown on either (100) or on (110) with a 4° tilt toward [111] at 500 and 300°C has been investigated by transmission electron microscopy. High perfection resulted for the layers grown on [001] oriented substrates whereas growth on the near [110] substrates resulted in compositional nonuniformities, macrosteps formation, and ordering of the group III elements. This difference in structural perfection between the two sets of samples was also reflected in differences in electrical properties.     

Derivation of growth mechanism of nano-defects in GaN from TEM data

Transmission electron microscopy (TEM) has been used to describe 'hollow' defects, e.g. nanotubes and pinholes (empty inside) formed in GaN hetero- and homoepitaxial layers. These defects are believed to be formed due to the presence of impurities and dopants. These defects appear to be even more deleterious than dislocations for the application of GaN in devices because their formation interrupts two-dimensional growth of quantum wells, and therefore will influence electrical and optical properties of the material. Experimental observations show that both these defects start from V-shaped indentations delineated by (1011) planes, and their density increases with higher concentrations of impurities or dopants. These 'hollow' defects are often found to be attached to dislocations, but the frequently observed termination of these defects inside the crystal eliminates dislocations as the source of these defects. Theoretical predictions also do not suggest that dislocations would have large-diameter empty cores like these of nanotubes and pinholes.     

Consumption patterns and labelling of fish and fishery products in Poland after the EU accession

Poland is a country with one of the lowest fish consumption levels in Europe. After accessing the European Union (EU) in 2004, Polish law including fish labelling legislation has been adapted. This study investigates consumers’ perceptions and awareness of fish information cues placed either on the package or on the shelf in a shop, with a special focus on information about the commercial designation of the fish species, the production method and the catch area. The study investigates the availability and visibility of this mandatory fish information in Poland. Results indicate that Polish consumers perceive labels on fish as a good source of information. However, consumer awareness about fish origin is still on a very low level.