Properties of polymer track membranes modified by grafting with poly(2-methyl-5-vinylpyridine) and poly(N-isopropylacrylamide)

The properties of track membranes (TM) based on poly(ethylene terephthalate) (PETP) and polypropylene (PP) and modified by radiation-induced graft polymerization of 2-methyl-5-vinylpyridine (MVP) andN-isopropylacrylamide (NIPAA) were studied. The rate of grafting and the limiting degree of grafting increase linearly as the pore diameter of TM increases. The gasdynamic and hydrodynamic pore diameters of modified TM were determined. The dependence of water permeability of TM modified by grafting with poly(2-methyl-5-vinylpyridine) (PMVP) on the degree of grafting passes through a maximum, which, according to the data of wetting angle measurements, corresponds to the maximum hydrophilicity. The negative χ-potential of TM changes sign after modification by grafting with PMVP. Thermosensitive TM based on PETP and PP were prepared by radiation-induced graft polymerization of NIPAA. The structure of modified TM was studied by electron microscopy and atomic force microscopy. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 858–864, May, 2000.     

Development of analytical method for the quality control of the fruit bark of Punica granatum L. (pomegranate) and antichemotatic activity of extract and rich fraction in punicalagins

Pomegranate is of current interest owing to the existing potential for industrial uses of fruit peels. This includes its availability as a raw vegetable material, a byproduct that constitutes residue in the use of the species and is recognized as a functional product, and beneficial health properties, as will be demonstrated in the studies cited. Therefore, it is necessary to ensure its effectiveness and safety. Toward this end, the aim of this study was to develop and validate an analytical method for the separation and quantification of total punicalagin present in the bark of the fruit of Punica granatum by HPLC. Purity tests such as water determination and total ashes were also performed. The ability of the extract and enriched fraction of punicalagin to inhibit leukocyte migration in vitro was determined by the Boyden's chamber method. The developed HPLC method demonstrated good separation and quantification of the punicalagin α and β anomers. The method is efficient and reliable, and can ultimately be used for the analysis of the extract of pomegranate. The crude extract and the fraction of punicalagins significantly inhibited leukocyte migration at concentrations of 1 and 10 μg/mL in relation to the negative control, indicating potential antichemotactic action.     

<Emphasis Type="Italic">L</Emphasis><Superscript>2</Superscript>-error estimates for Dirichlet and Neumann problems on anisotropic finite element meshes

An L ²-estimate of the finite element error is proved for a Dirichlet and a Neumann boundary value problem on a three-dimensional, prismatic and non-convex domain that is discretized by an anisotropic tetrahedral mesh. To this end, an approximation error estimate for an interpolation operator that is preserving the Dirichlet boundary conditions is given. The challenge for the Neumann problem is the proof of a local interpolation error estimate for functions from a weighted Sobolev space.     

A new method for the correlation functions of thex-y model

A new method is introduced to calculate the dynamical transverse correlation functions of the anisotropicx–y chain at finite temperature. Its application to the disordered system is proposed.     

X → 2γ from π p → neutral meson + neuron at 3.8 GeV/c

We report on a measurement for the branching-ratio X⁰ → 2γ/X⁰ ar all. Our result is X⁰ → 2γ/X⁰ → all = (2.9 ± 0.9)%.     

A posteriori error estimation of residual type for anisotropic diffusion-convection-reaction problems

This paper presents a robust a posteriori residual error estimator for diffusion-convection-reaction problems with anisotropic diffusion, approximated by a SUPG finite element method on isotropic or anisotropic meshes in R^d, d=2 or 3. The equivalence between the energy norm of the error and the residual error estimator is proved. Numerical tests confirm the theoretical results.     

Assay of caffeoylquinic acids in Baccharis trimera by reversed-phase liquid chromatography

Baccharis trimera commonly named ‘carqueja’, is wide-spread in South America and are used as raw material for herbal medicines. A reversed-phase liquid chromatography (RP-LC) method coupled to diode array detector was developed for the analysis of caffeoylquinic acids (CQAs), the main compounds responsible for its digestive activity. The identity of the quinic acids was established by mass spectrometry and were them: 5-O-[E]-caffeoylquinic acid, 3,4-O-[E]-dicaffeoylquinic acid, 3,5-O-[E]-dicaffeoylquinic acid, 4,5-O-[E]-dicaffeoylquinic acid and a tricaffeoylquinic acid. The RP-LC method for the quantitation of the caffeoylquinic acids was validated according to ICH guidelines, based on the following parameters: linearity, selectivity, robustness, limits of detection and quantification, precision and recovery. Hydroalcoholic extracts were prepared by the maceration of the plant material with ethanol:water 1:1 (v/v) in a 0.1:25 g mL^?1 plant:solvent ratio in a water bath at 40 °C. Validation data indicated that the HPLC method proposed is suitable for the analysis of caffeoylquinic acids in B. trimera raw material. The results of the LOD and LOQ analyses for the 5-CQA were 4.1 μg mL^?1 and 12.5 μg mL^?1, respectively, 1.3 μg mL^?1, 3.9 μg mL^?1 for 4,5-diCQA and 1.7 μg mL^?1, 5.1 μg mL^?1 for triCQA. The levels of total CQAs ranged from 2.1 to 4.0 g% (w/w). The influence of season harvest and site collection was also evaluated and variations were observed in the results and can be related to phonologic phase, different locations, seasons and soil. Long term and photostability of plant material were carried out and was observed a stable behavior during the time of the experiments.     

Weak hydrogen bonding as a basis for concentration-dependent guest selectivity by a cyclophane host

Crystalline inclusion complexes between the cyclophane 1 and three isomers of picoline and lutidine were grown and their properties and structures were studied by X-ray analysis, thermal gravimetry (TG), and differential scanning calorimetry (DSC). In competition experiments, the cyclophane host, which by itself is only able to form weak Cbond;H.acceptor hydrogen bonds, is able to discriminate between the different picoline or lutidine isomers, although in some cases a strong concentration dependence of the preferred isomer is observed. In the three-component experiments, inclusion of 4-picoline is strongly favored when X(4-picoline)>0.35-0.39. Very similar results were obtained in the lutidine series. The fact that 2,4-lutidine is favored when X(2,4-lutidine)>0.2 indicates that the host prefers the isomer with the methyl group in 4-position relative to the nitrogen atom. The selectivities observed can be explained based on the assignment of the inclusion complexes to different adduct classes. In the case of the picoline isomers, the preference of 4-picoline was in good agreement with the calculated lattice energies for this series. The present work also shows that caution is advisable when deducing selectivity of crystalline inclusion compounds from guest competition experiments.