Determination of catechin and epicatechin in the peel of apple varieties resistant and non-resistant to apple scab

Catechin and epicatechin were analysed in the peel of six apple cultivars (three resistant and three non-resistant to apple scab). Two methods of analytical sample preparation following extraction were tested: solid phase extraction and column separation with Sephadex LH-20 coupled to a differential refractometric detector. Prior to GC and GC-MS analyses, these compounds were silylized. This permitted co-injection with standards and the comparison of retention values and mass spectra with those recorded for standards. The content of catechin and epicatechin in apple peel is discussed in relation to the resistance of apple trees to scab.     

Reducibly degradable hydrogels of PNIPAM and PDMAEMA: Synthesis,stimulus‐response and drug release

Reducibly degradable hydrogels of poly(N‐isopropylacrylamide) (PNIPAM) and poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by the combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and click chemistry. The alkyne‐pending copolymer of PNIPAM or PDMAEMA was obtained through RAFT copolymerization of propargyl acrylate with NIPAM or DMAEMA. Bis‐2‐azidyl‐isobutyrylamide of cystamine (AIBCy) was used as the crosslinking reagent to prepare reducibly degradable hydrogels by click chemistry. The hydrogels exhibited temperature or pH stimulus‐responsive behavior in water, with rapid response, high swelling ratio, and reproducible swelling/shrinkage cycles. The loading and release of ceftriaxone sodium proved the feasibility of the hydrogels as the stimulus‐responsive drug delivery system. Furthermore, the presence of disulfide linkage in AIBCy favored the degradation of hydrogels in the reductive environment. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3604–3612, 2010     

Modeling of diffusive transport of benzoic acid through a liquid membrane

A model of diffusive transport of benzoic acid through a liquid membrane (LM) separating two aqueous solutions, based on diffusion layers and the assumption of a steady state, has been developed and tested using experimental results. It has been found that a model with the apparent partition coefficient dependent on the concentration is able to describe the time dependence of acid concentration in LM with and without a maximum on that dependence. The quality of the model fit with the single apparent diffusion coefficient of benzoic acid is the same as the one which takes into account the diffusion of benzoic acid in different forms (undissociated and dissociated form in aqueous phase, monomer and dimer in organic phase); however, in the second case, the model becomes overparameterized. Assuming that the partition and diffusion coefficients are constant, the diffusion layer model corresponds to the model of reversible consecutive reactions. Analytical solution for such case is given. Apart from the partition equilibrium, also kinetics of partitioning was considered. It was shown that in some basic situations both cases yield identical results.     

Structure and atropisomerisation of new diastereomeric gossypol Schiff bases with (R)-(+)-2-amino-3-benzyloxy-1-propanol studied by NMR,ECD and DFT methods

Gossypol Schiff base with (R)-(+)-2-amino-3-benzyloxy-1-propanol 1 was synthesised and resolved by HPLC method into diastereomers to study their atropisomerisation process. The spectroscopic analysis performed by one- and two-dimensional NMR, UV–vis and FT-IR methods indicated that the compound exists in solution as an enamine-oxo tautomer. The ECD measurements and TD-DFT calculations allowed us to unambiguously determine the configuration about the axially chiral biaryl moiety of 1. The conditions of the atropisomerisation processes of diastereopure gossypol Schiff bases (S_AX,R)-1 and (R_AX,R)-1 were determined on the basis of ECD and NMR measurements. Exposure of the diastereomers of 1 to sunlight and to the light at λ = 254 nm significantly accelerated the atropisomerisation when compared to its rate in the dark.     

Temperature dependent in situ doping of ALD ZnO

This study on ALD grown ZnO layers is aimed at the systematic study of the effect of incorporation of different Al contents on the properties of the layers. An alternate precursor pulse method was used for layer deposition. Optimal doping was achieved at 210 °C at 2 at% Al content. A relationship between crystalline morphology versus temperature and aluminium incorporation was established.     

A ruthenium(II) hydride carbonyl complex with 4-phenylpyrimidine as co-ligand

The reaction of [RuHCl(CO)(PPh₃)₃] with 4-phenylpyrimidine gave a new ruthenium(II) complex, namely [RuHCl(CO)(PPh₃)₂(pyrim-4-Ph)]. The complex has been studied by IR and UV?Cvis spectroscopy and by X-ray crystallography. The molecular orbitals of the complex have been calculated by density functional theory. The spin-allowed singlet?Csinglet electronic transitions of the complex have been calculated by time-dependent DFT, and the UV?Cvis spectrum of the compound has been discussed on this basis. The emission properties of the complex were also studied.     

Corrigendum to “Convexity and concavity constants in Lorentz and Marcinkiewicz spaces” [J. Math. Anal. Appl. 343 (2008) 337-351]

In this note we state the accurate formulas of convexity and concavity constants in Lorentz spaces, correcting the formulas from Kamińska and Parrish (2008) [2].     

Investigation of InSb(1 1 0) and InSb(1 1 1) surfaces by means of target current (VLEED) spectroscopy and LEED

In this paper, we present experimental results of target current (TCS) and LEED investigation of well-oriented InSb(1 1 0) and InSb(1 1 1)-A and InSb(1 1 1)-B crystals. TCS results are interpreted in terms of very low electron diffraction (VLEED) and empty band signatures. To examine to which extent the TCS spectra reflect the bulk or surface electronic properties of InSb(1 1 0), thin layers of indium have been evaporated and the corresponding spectrum changes have been investigated.     

A new approach to the study of the α–σ phase transformation

It is demonstrated that the kinetics of the α-σ phase transformation in the Fe-Cr based alloys can be studied from the average isomer shift. Using this new approach it is shown that the size of grains significantly affects the formation of the σ-phase, while that of the α-phase does not depend on the microstructure. This revised version was published online in August 2006 with corrections to the Cover Date.