Matched/Mismatched interaction of a cyclic hexapeptide with ion pairs containing chiral cations and chiral anions

The binding of a chiral quaternary ammonium ion to a cyclopeptide containing aromatic amino acid subunits is affected not only by the configuration of the cation but also by the configuration of the chiral counterion. Analysis of the binding equilibria shows that complex formation involves interaction of the whole ion pair with the host indicating that steric requirements of the anion influence complex geometry and stability.     

The problem of adsorption on silicagel in a liquid scintillation radiometry of14C labelled compounds

By means of liquid scintillation spectrometry we investigated the counting efficiency of the samples containing toluene solution of scintillator (PPO, butyl-PBD, PT) and 1-methyl[2−¹⁴C]imidazolidinone-2 adsorbed on the silicagel, depending on concentration of scintillator, mass of radioactive compound, and mass of another nonactive compound introduced to samples as an impurity. For the sake of comparison the efficiency of counting homogeneous samples and the ones with Ba¹⁴CO₃ deposit was determined. It was found, that the efficiency of detection of a radioactive compound adsorbed on the silicagel is conditioned by composition of adsorptive layer on the support surface.     

Bose-Einstein correlations for pions produced inp p collisions at 360 GeV/c

Zeitschrift für Physik C Particles and Fields - Correlations among identically charged pions were measured for pions produced inp p collisions at 360 GeV/c using the EHS spectrometer. The...     

Numerical Investigation of Particulate Flow over a Backward‐Facing Step

Flow separation and recirculation caused by a sudden expansion in the channel geometry in the form of a backwardfacing step (BFS) appear in numerous practical applications. Additionally, BFS flow has been used as a generic test case to study fundamental flow properties, such as separation or re‐attachment. In the present work, BFS flow laden with dispersed particles is investigated by numerical simulations using a spectral element method [1]. The motion of the dispersed particles is computed by Lagrangian particle tracking. In a first step, only the influence of the flow on the particles is accounted for, while possible effects of the particle motion on the flow are neglected. Spatial distribution of the particles is investigated, and effects of different wall‐particle interaction models on the computational results are examined.     

Influence of mass loading on particle-laden turbulent channel flow

Results are presented for the behavior of particle-laden gases in a moderate Reynolds number vertical channel down flow. The effects of mass loading on the gas-phase turbulence and particle concentration are studied. A direct numerical simulation including models of wall-particle interaction is conducted. It is confirmed that particle feedback causes the turbulence intensities to become more non-isotropic as the particle loading is increased. The particle concentration exhibits a maximum close to the wall and a slight increase in the middle of the channel. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phytochemical Analysis and Anti-Cancer Properties of Extracts of Centaurea castriferrei Borbás & Waisb Genus of Centaurea L

The Centaurea L. (Asteraceae) genus includes many plant species with therapeutic properties. Centaurea castriferrei Borbás & Waisb is one of the least known and least described plants of this genus. The aim of the study was the phytochemical analysis of water and methanol–water extracts (7:3 v/v) obtained from the aerial parts of the plant as well as evaluation of their anticancer activity. Quantitative determinations of phenolic compounds and flavonoids were performed, and the antioxidant potential was measured using the CUPRAC method. The RP-HPLC/DAD analysis and HPLC-ESI-QTOF-MS mass spectroscopy were performed, to determine the extracts’ composition. The antiproliferative activity of the obtained extracts was tested in thirteen cancer cell lines and normal skin fibroblasts using MTT test. Regardless of the extraction method and the extractant used, similar cytotoxicity of the extracts on most cancer cell lines was observed. However, the methanol–water extracts (7:3 v/v) contained significantly more phenolic compounds and flavonoids as well as showing stronger antioxidant properties in comparison to water extracts. Centaurea castriferrei Borbás & Waisb is a rich source of apigenin and its derivatives. In all tested extracts, chlorogenic acid and centaurein were also identified. In vitro research revealed that this plant may be a potential source of compounds with anticancer activity.