Pathwise global attractors for stationary random dynamical systems

Summary The asymptotic behaviour of random dynamical systems in Polish spaces is considered. Under the assumption of existence of a random compact absorbing set, assumption supposed to hold path by path, a candidate pathwise attractorA() is defined. The goal of the paper is to show that, in the case of stationary dynamical systems,A() attracts bounded sets, is measurable with respect to the -algebra of invariant sets, and is independent of when the system is ergodic. An application to a general class of Navier-Stokes type equations perturbed by a multiplicative ergodic real noise is discussed in detail.     

Synthesis of arylboronates by the palladium catalysed cross-coupling reaction in ionic liquids

The palladium catalysed cross-coupling reaction of aryl iodides and bromides with pinacolborane in 1,3-dialkylimidazolium tetrafluoroborates and hexafluorophosphates producing arylboronates is described.     

Flow-through microdispenser for interfacing micro-HPLC to Raman and mid-IR spectroscopic detection

A flow-through microdispenser has been coupled to a micro HPLC separation system and used as a solvent elimination interface for Fourier transform infrared (FTIR) and Raman spectroscopic detection of the separated compounds. Using the microdispenser picoliter sized droplets can be generated and deposited on an appropriate target placed on a computerized x, y-stage. Evaporation of volatile solvent and buffer is rapid and allows analysis of the obtained dry deposits by various techniques. Due to the destruction free character of Raman and FTIR spectroscopy they can be applied sequentially to interrogate the same deposit. In the reported application five phenolic acids typically present in wine have been separated on a C-18 column technique using a mixture of water, methanol and acetic acid as mobile phase. For spectrum acquisition infrared and Raman microscopes have been used. The spectra recorded from the dried deposits of the separated compounds agreed well with the reference spectra of corresponding components.     

Modification of polysulfone membranes 4. Ammonia plasma treatment

The effect of NH₃ and NH₃/Ar plasma on ultrafiltration polysulfone membranes have been studied. Results of contact angle, FTIR-ATR and X-ray photoelectron spectroscopy experiments clearly showed that both plasmas introduced hydrophilic, nitrogen- and oxygen-containing moieties on the polymer surface and that NH₃/Ar plasma was more efficient. That plasma was also more aggressive--signs of strong etching could be seen on the SEM pictures. Redeposition of etched material seemed to take place inside the pores. On the contrary, ammonia plasma was soft and caused cleaning the surface and pores enlargement. Performance of ammonia plasma modified membranes was greatly improved and independent on solution pH. The last observation proved amphoteric character of the surface. NH₃/Ar plasma treatment gave membranes of acidic surface and filtration indices not so good as for ammonia plasma.     

Silicate Xerogels with Dopant-Induced Chirality

A series of silicate xerogels with entrapped chiral amino acids have been obtained via sol-gel technology. The transparent, glassy samples obtained exhibit chirality in the bulk due to the presence of the entrapped asymmetric molecules. Measurements of the optical activity of the doped xerogel samples revealed that the entrapment did not significantly influence the optical activity observed for liquid solutions of the amino acids. Thus, the sol-gel method enables the preparation of amorphous optical materials exhibiting properties of strictly spatially defined molecular systems. Apart from the obvious optical applications, such porous materials with asymmetric centers might find interesting applications in chiral chemical syntheses and separations.     

Is planarity of pyridin-2-yl- and pyrazin-2-yl-formamide thiosemicarbazones related to their tuberculostatic activity? X-ray structures of two pyrazine-2-carboxamide-N′-carbonothioyl-hydrazones

Crystal structures of two title compounds and several their relatives known earlier reveal conservative and characteristic features, which may be related to their tuberculostatic activity. The molecules are predominantly planar due to conjugation through five successive bonds in the zwitterionic fragment S⁻–C(sp²)–N–NH⁺–C(sp²)–NH₂ and intramolecular hydrogen bonds, which prevent rotation of the adjacent pyrazine (or pyridine) ring. It has been suggested that in spatial sense such planar molecules resemble acridines intercalating with nucleic acids and that similar process may be responsible for tuberculostatic activity of the title pyrazine-2-carboxamide-N′-carbonothioyl-hydrazones.     

Crystal Structures of 1,5,9,18,22,26-Hexaaza[11.11]-p-cyclophane Adducts; Two-dimensional Supramolecular Networks

Two newly identified supramolecular structures arise from self-assembly of the macrocyclic 1,5,9,18,22,26- hexaaza[11.11]-p-cyclophane salts with o-nitrophenol (C₂₈H₅₀N₆)⁴⁺·4(C₆H₄NO₂O)⁻ (1) and with HCl (C₂₈H₅₂N₆)⁶⁺·6Cl^-·4H₂O (2). In both cases two-dimensional supramolecular sheets are formed.     

Low temperature crystal and molecular structure of nitrobenzene

The crystal and molecular structure of nitrobenzene was determined at 103 K by X-ray diffraction, yieldingR=0.034 and a highly precise geometry of the molecule (esds of bond lengths 0.001 Å and bond angles 0.1°). The bond angles in the ring agree very well with additive scheme based on angular substituent parameters. X-X electron density maps support the view that the C-N bond does not exhibit-character, and, hence, the nitro group interacts with the ring mostly by inductive effects.     

Multicomponent analysis with a computerized flow injection system using LED photometric detection

An original computer-controlled solid-state photometer has been developed and its potential for simultaneous multicomponent flow-injection analysis of binary and ternary mixtures is demonstrated. The device is simple in construction. Its principle of operation is based on rapid sequential measurements of the absorbance of the complexes formed by the analytes with chromogenic reagents at the wavelengths corresponding to the emission maxima of three light emitting diodes (563, 580 and 638 nm).     

Stimuli-responsive surface crystallization of phospholipids from bimodal colloidal particles

These studies focus on the effect of phospholipids in the presence of ionic surfactants on the behavior of poly(methylmethactrylate/n-butyl acrylate) (p-MMA/nBA) colloidal particles during film formation. With the presence of two surfactants, it is possible to obtain particles that exhibit two distinct particle sizes. The presence of hydrogenated soybean phosphatidylcholine (HSPC) and sodium dioctyl sulfosuccinate (SDOSS), which stabilize these bimodal colloidal dispersions, has a significant effect on the mobility of individual components during coalescence. Specifically, the presence of HSPC inhibits migration of SDOSS to the film-air (F-A) interface. Furthermore, the presence of electrolyte species such as aqueous CaCl2 has a very pronounced effect on film formation. When the Ca2+/HSPC ratio is 0.1/1.0, SDOSS is released to the F-A interface during coalescence. At 2.0/1.0 Ca2+/HSPC, HSPC diffuses to the F-A interface and crystalline domains consisting of HSPC are formed. This stimuli-responsive behavior is confirmed using IRIR imaging that ultimately exhibits different surface morphologies. These studies illustrate for the first time that it is possible to control the release of two different surface-active species during coalescence that form crystalline domains.