Influence of photodynamic effect on biological activity of PBR–PP complexes

The aim of this study was to examine the influence of photodynamic effect on biological activity of PBR–PP complexes. These measurements were performed in pH dependent environment. Constant concentration of solubilized receptor was titrated with increasing concentration of porphyrins (PPIX, Hp, PP(Arg)₂, Hp(Arg)₂, PP(Gly)₂, PP(Ala)₂, PP(Ser)₂, PP(Phe)₂) and binding constants were calculated. PBP–PP mixtures were illuminated with 3 J, 5 J or 10 J of blue light and changes in protein fluorescence was recorded. Experimental data were fitted to weak and strong binding models. As a result for all derivatives weak binding model was the best fitted. The strongest binding showed PPIX in pH 7.4 and with pH drop binding constants showed greater values for all examined derivatives. Out of amino acid derivatives the strongest binding was noticed for PP(Gly)₂ and PP(Phe)₂ and for the last one pH influence was not observed.     

Directing the growth of highly aligned gold nanorods through a surface chemical amidation reaction

This paper describes the seed-mediated growth of highly aligned gold nanorods (Au NRs) over large areas directly on a Si(100) surface. The Si(100) surface is NH2-functionalized with (aminopropyl)triethoxysilane (APTES) followed by a DCC-catalyzed surface amidation reaction with acetic acid. After exposure to a gold nanoparticle (Au NP) "seed" solution, chemical seed-mediated growth of the surface-bound seeds via reduction of AuCl4- by ascorbic acid in the presence of cetyltrimethylammonium bromide leads to the growth of highly aligned Au NRs on the surface. About 80% of the NRs are aligned in the same direction within a +/-30 degrees range. Au NRs account for 19% of the nanostructures with average aspect ratio (AR) of approximately 20. The alignment direction did not correlate with the atomic arrangement of the Si(100) crystal since it varied over different regions of the sample, rotating by 90 degrees from top to bottom of an approximately 5 mm sample. Si crystallinity may still be important since alignment is not observed on amorphous glass. Surface functionalization is the key since alignment is only observed following the amidation reaction and not on NH2-functionalized, SH-functionalized, or bare Si(100) surfaces. Alignment also occurred for Au NRs grown on Si(100)/APTES reacted with succinic acid and on Ag NRs grown on Si(100)/APTES/acetic acid surfaces. This unique alignment of metal NRs promoted by a surface amidation chemical reaction may find use in nanoelectronics, chemical sensing, and plasmonics applications.     

Substitution and proton doping effect on SrZrO3 behaviour: high‐pressure Raman study

The high‐pressure Raman studies of pure, Yb‐modified, protonated and non‐protonated SrZrO₃ dense ceramics were performed between 0.1 and 40 GPa using a diamond anvil cell. Lanthanide‐modified, protonated SrZrO₃ perovskites are potential materials for electrolytic membrane in fuel cells and electrolysers working at medium temperature. The comparison of the Raman spectra shows important differences in the pressure behaviour between the pure and Yb‐modified SrZrO₃ ceramics. SrZrO₃ exhibits a rigid structure without any structural modification, whereas for both SrZr_0.93 Yb_0.07 O_2.965 and SrZr_0.93 Yb_0.07 O_2.962 H_0.003 a sequence of structural modifications at 10, 20 and 35 GPa is revealed. The character of these structural modifications is very similar to that observed as a function of the temperature (orthorhombic Pnma 750 °C → pseudo‐tetragonal Imma 840 °C → tetragonal I4/mcm 1070 °C → cubic Pm3m), which suggests that they can be considered as the phase transitions. Despite the low level of proton content (0.3% mole/mole), significant difference between protonated and non‐protonated compounds is observed for the 700–750 cm⁻¹ doublet assigned to the Zr O octahedron stretching mode, perturbed by an oxygen atom vacancy and/or neighbouring Yb ion. The location of proton is discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Monotonicity methods in generalized Orlicz spaces for a class of non‐Newtonian fluids

The paper concerns existence of weak solutions to the equations describing a motion of some non‐Newtonian fluids with non‐standard growth conditions of the Cauchy stress tensor. Motivated by the fluids of strongly inhomogeneous behavior and having the property of rapid shear thickening, we observe that the L^p framework is not suitable to capture the described situation. We describe the growth conditions with the help of general x‐dependent convex function. This formulation yields the existence of solutions in generalized Orlicz spaces. As examples of motivation for considering non‐Newtonian fluids in such spaces, we recall the electrorheological fluids, magnetorheological fluids, and shear thickening fluids. The existence of solutions is established by the generalization of the classical Minty method to non‐reflexive spaces. The result holds under the assumption that the lowest growth of the Cauchy stress is greater than the critical exponent q=(3d+ 2)/(d+ 2), where d is for space dimension. The restriction on the exponent q is forced by the convective term. Copyright © 2009 John Wiley & Sons, Ltd.     

Dynamic self-assembly of nanoparticles using thermotropic liquid crystals

ABSTRACT

3D nanoparticle-based materials with reconfigurable structure have gained vast attention due to the unique possibility of tailoring nanoparticle-related quantum confinement effects. These properties make active nanoparticle assemblies promising candidates for future optoelectronic and metamaterial technologies; however, integration of these materials into real-world applications is still challenging. In this context, the use of stimuli responsive liquid-crystals (LCs) offers a fascinating and industrially feasible strategy for active directing of NPs. Here, we briefly review LCs/NPs hybrid systems in which dynamic behaviour is achieved by affecting either LC matrix or LC ligands. We also experimentally evaluate a complementary strategy based on directly affecting metallic core of LC-covered NPs in an Ostwald ripening process.     

High throughput method for multielemental analysis of horse hair by oaTOF-ICP-MS

An approach for high throughput reliable multielemental analysis of trace elements in a large number of horse hair samples was designed. Suitability of time-of-flight mass spectrometer (oaTOF-ICP-MS) for fast determination of unlimited numbers of isotopes in the low volume samples was demonstrated. Due to quasi-simultaneous capability of the oaTOF-ICP-MS the large number of highly valuated data with unaffected isotopic ratio in a very short time could be obtained. The choice of horse hair was obvious because of easy reachability and clear conception about horse nutritional habits and stabling. Such large data set with preserved isotopic ratios is ideal for statistical evaluation which could reveal some interesting interconnection between elemental composition of horse hair and the way of stabling, feeding, etc. Statistical treatment of the data is not a part of this study and will be presented later. We collected one hundred horse hair samples from horse stables through Czech Republic. Samples were washed by optimized washing process to eliminate exogenic contamination prior to digestion and following analysis. A determination of 36 elements (As, Au, B, Be, Cd, Ce, Co, Cr, Dy, Er, Eu, Ga, Gd, Ge, Ho, La, Li, Lu, Nd, Ni, Pb, Pd, Pr, Pt, Rb, Sb, Sc, Sm, Ta, Tb, Te, Tm, U, V, Y, Yb) in horse hair by oaTOF-ICP-MS was optimized. A throughput of 100 samples with unlimited numbers of isotopes per 6 h was achieved. Proposed very fast multielemental method preserves isotopic ratios, and therefore, is undoubtedly highly suitable for statistical studies. Detection limits of the proposed method ranged from 0.13 μg kg^?1 (Eu, Gd, Tm) to 27.9 μg kg^?1 (Au), except for Ni (48.5 μg kg^?1) that is probably affected by contamination raised from nickel cones.     

Holomorphic Extensions in Smooth Toric Surfaces

This article describes the Hartogs and the Hartogs?CBochner extension phenomena in smooth toric surfaces and the connection with the first cohomology group with compact support. The affirmative and negative results are proved using topological, analytic, and algebraic methods.     

Analysis of oxidised and reduced phytochelatins in pea and lupin plants using HPLC/MSn

Plants exposed to heavy metals activate a detoxification system capable of chelating and transporting these harmful ions to vacuoles. Phytochelatins–low molecular weight oligopeptides containing thiols such as glutathione and cystein–have been reported to play a very important role in this respect. High performance liquid chromatography coupled to the electospray ion trap mass spectrometer (HPLC-ESI-IT-MS) was used for identification of phytochelatins induced by Cd²⁺ and Pb²⁺ in roots, stems and leaves of pea (Pisum sativum L.) and yellow lupin (Lupinus luteus L.). This approach enabled unambiguous identification of phytochelatins in plant tissues and detection of phytochelatins and homophytochelatins in reduced as well as in oxidised form. Significant differences were detected in phytochelatin relative amounts and profiles in different parts of plants treated with heavy metals. Roots of both plant species contained mainly reduced phytochelatins, reduced and oxidised forms of these peptides were observed in stems in similar amounts, whereas only the oxidised phytochelatins were present in leaves.