A chemical synthesis of two novel phenyl glycosides of trisaccharides related to acetylarabinoxylan is described. The trisaccharides bear acetyl and arabinofuranosyl moieties at the non-reducing-end xylopyranosyl residue, which is substituted at positions 2 and 3. Both compounds were treated with various xylan deacetylases classified in different carbohydrate esterase (CE) families and significant differences between the families were found. While the arabinosylation hampers deacetylation by CE2-CE5 and CE12 family members, both epitopes are deesterified by CE1 and in particular CE6 enzymes. The 3-O-acetylated 2-O-arabinosylated compound is also processed by CE7 and majority of CE16 esterases, but not by a hitherto non-classified Flavobacterium johnsoniae acetylxylan esterase. The data suggests that a slow deesterification of the 2-O-acetylated 3-O-arabinosylated compound may be due to the acetyl group migration followed by deacetylation of this migration product. 相似文献
Fire Technology - Textile-reinforced concrete is currently most frequently used for non-load–bearing structures, but there is a vision for also using it in load–bearing construction... 相似文献
The effects of age, vegetation density (normalised difference vegetation index [NDVI]) and vegetation type on temperature fluctuations were studied in post-coal-mining sites in the Czech Republic. NDVI and surface temperature were obtained from an airborne multispectral aerial photograph and FLIR infrared camera. The difference between morning and afternoon temperature was assumed as a measure of the temperature buffering ability of the ecosystem. Buffering increased with increasing NDVI but also depended on the type of vegetation, reclaimed sites have significantly higher buffering than unreclaimed sites. In contrary to grasslands, woody vegetation gradually increased temperature buffering capacity with plot age. Topsoil application substantially increased buffering capacity. 相似文献
The present work investigates texture evolution stages in grain-oriented steel heat-treated using unconventional conditions. The Fe–3%Si steel taken after final cold rolling reduction from an industrial line was subjected to a laboratory isothermal annealing at different temperatures. The annealing temperatures were varied in a range of 850–1150 °C. During the annealing each specimen was heated at 10 °C/s and kept at the stated temperature for 5 min. Development of microstructure and texture in the annealed specimens were followed by the DC measurements of magnetic properties. The grain oriented steel, taken from the same industrial line after final box annealing was also analyzed and compared with the laboratory annealed specimens. It was shown that there is an optimal temperature region that, with combination of a fast heating rate, led to the best conditions of a drastically reduced development time of the {110} < 001 > crystallographic texture in the cold rolled grain-oriented steel. Materials heat treated below the optimum temperature region account for a primary recrystallization, while applying heat above this region leads to a secondary recrystallization without abnormal grain growth. Moreover, in the optimum temperature range, there was a particular temperature leading to the most optimal microstructure and texture. The magnetic properties, measured after the optimal heat treatment, were close to that measured on specimens taken after the final box annealing. The electron back scattered diffraction measurement technique revealed that sharpness of the {110} < 001 > crystallographic texture, developed at the optimum temperature is comparable to the steel taken after the industrial final box annealing. This fact is evidence that there is a temperature where the abnormal grain growth proceeds optimally. 相似文献
Surface properties of commercially available poly(ethylene terephthalate) (PET) foils of different thicknesses (3, 13, 23, 50, and 100 μm) were characterized using different analytical methods. Surface roughness and morphology were determined by atomic force microscopy, goniometry was used for determination of contact angle (wettability of surface) and electrokinetical analysis (zeta potential) for characterization of surface polarity and conductivity. X-ray photoelectron spectroscopy was used for characterization of PET surface chemistry. Infrared spectroscopy and differential scanning calorimetry (DSC) were used for determination of crystallinity portion. By DSC analysis, it was confirmed that the crystallinity portion depends on the foil thickness. Most important result of this study is that the surface properties of PET foils depend not only on the foil thickness but also on the foil side under study. This finding may be of importance for future experiments performed on PET foils and for their application in tissue engineering or microelectronics. 相似文献
GlcNAc-coated glycodendrimers, which are polyvalent glycomimetics, display strong in vitro affinity for the rat natural killer cell protein-1A (NKR-P1A), a C-type lectin-like receptor of natural killer (NK) cells in rats, humans and some strains of mice. Administration of these compounds in vivo results in a substantial increase in the antitumour activity with involvement of the natural cell immunity. To clarify the in vitro and in vivo fate of these molecules, we synthesized labelled glycodendron analogues of the previously studied glycodendrimers. Labelling with fluorescent tags enabled the localization of the glycodendrons in white blood cells, tumours and other tissues by using different imaging techniques such as fluorescence and confocal microscopy. These studies are useful for probing the mechanism of action and fate of artificial ligands and the cell receptors involved. 相似文献
Some real-life optimization problems, apart from dependence on the combination of state variables, also show dependence on the complexity of the model describing the problem. Changing model complexity implies changing the number of decision space dimensions.
A new method called Particle Swarm Optimization for Variable Number of Dimensions is developed here. The well-known particle swarm optimization procedure is modified to handle spaces with a variable number of dimensions within a single run. Some well-known benchmark problems are modified to depend on the number of dimensions. Novel performance metrics are defined in the article to evaluate convergence properties of the method. Some recommendations for setting the optimization are made according to results of the method on the proposed benchmark test suite. The method is compared with conventional swarm strategies able to solve problems with variable number of dimensions. 相似文献
The ability to form an efficient interface between material and neural cells is a crucial aspect for construction of neuroelectrodes. Diamond offers material characteristics that could, to a large extent, improve the performance of neuroelectrodes. The greatest advantage of diamond is a large variety of material and surface properties such as electrical conductivity, surface morphology, and surface chemistry. Such a variety of material characteristics can lead to various cellular responses. Here, the authors compare survival, adhesion, and neurite formation of primary neurons on diamond thin films of various morphologies and treatments with several types of polymers commonly used to enhance cell adhesion. The authors find that the variation of surface roughness of nanocrystalline diamond film when coated with polymer does not have a major influence on neuron survival or adhesion. The adhesion of neurons can be influenced by the selected type of polymer coating. High molecular weight of polyethylenimine results in lower viability, adhesion, and neurite formation. The addition of laminin to treated films do not lead to significant improvements in neuron adhesion and neurite development. Their findings emphasize the importance of the correct polymer treatment over morphological properties of diamond thin films as a material for forming interfaces with primary neurons. 相似文献
Growing demands on the engineering properties of cement based materials and the urgency to decrease unsuitable ecologic impact
of Portland cement manufacturing represent significant motivation for the development of new cement corresponding to these
aspects. One category represents prospective alkali activated cements. A significant factor influencing their properties is
alkali activator used. In this paper we present a new high effective alkali activator prepared from silica fume and its effectiveness.
According to the results obtained this activator seems to be more effective than currently used activators like natrium hydroxide,
natrium carbonate, and water glass. 相似文献