Supported ionic liquid catalysis investigated for hydrogenation reactions

The concept of supported ionic liquid catalysis (silc) has successfully been applied to hydrogenation reactions, which significantly reduced the required amounts of ionic liquid phase and enabled the usage of fixed-bed technology; the resulting catalysts exhibited high activity and outstanding stability.     

An evanescent field driven mono-molecular layer photoswitch: coordination and release of metallated macrocycles

Photoswitching of 'on' and 'off' coordination sites in a self assembled monolayer containing the 4-(arylazo)pyridine chromophore has been achieved using the evanescent field and illustrated through coordination and photon induced release of zinc tetraphenylporphyrin.     

Inhibition of trypanothione reductase by substrate analogues

Trypanothione reductase (TR) catalyzes the NAPDH-dependent reduction of the spermidine-glutathione conjugate trypanothione, an antioxidant found in Trypanosomatid parasites. TR plays an essential role in the parasite's defense against oxidative stress and has emerged as a prime target for drug development. Here we report the synthesis of several trypanothione analogues and their inhibitory effects on T. cruzi TR. All are competitive inhibitors with K(i) values ranging from 30 to 91 microM.     

Site-specific cross-linking of nucleic acids using the abasic site

[formula: see text] An efficient site-specific cross-linking reaction between two carbohydrate residues present in two complementary DNA sequences is described. One oligodeoxynucleotide, 5'd(GGCTGA*CTGCG)3', carries an amino nucleophile tethered to the 2'-hydroxyl of an adenosine residue (A*). The target electrophile is an abasic site generated in the complementary sequence, 5'd(CGCAGDCAGCC)3' (D represents the deoxyribose). The cross-linking reaction was carried out by a reductive amination reaction in > 95% yield.     

A high temperature Mössbauer effect study of iron-doped YBa2Cu3O7 superconductor

Superconducting YBa₂Cu_2.955Fe_0.045O₇ has been studied at temperatures between 300 and 1000 K. Spectra were recorded on a sample which was sealed as a pellet pressed with boron nitride. An atmosphere of oxygen was maintained in the sample region at all times. At temperatures up to 900 K, we observed the four iron sites A, (Cu(1) chain-site; square planar oxygen coordination with O(5) vacancy on thea-axis), B, (Cu(2) plane-site; square pyramidal oxygen coordination), C, (Cu(1) chain-site; square pyramidal oxygen coordination with O(5) site occupied) and D, (Cu(1) chain-site; quasi-tetrahedral oxygen coordination with O(4) vacancy along theb-axis). At temperatures up to 700 K, the relative area of the B and C sites remained nearly constant as the temperature was increased. However, the area of the A site decreased while, the D site area increased with increasing temperature. At all times, the total area of sites A and D remained constant, thereby indicating the possibility of oxygen atom hopping in thea-b plane. The quadrupole splitting of each site, except the B site, decreased linearly with increasing temperature.Research supported in part by the Old Dominion University Undergraduate Research Program.     

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The energy dependence of 6Li optical potentials

The energy dependence of ⁶Li optical potentials for elastic scattering from ²⁸Si, ⁴⁰Ca, ⁵⁸Ni, ⁹⁰Zr and ²⁰⁸Pb targets has been investigated by simultaneously fitting several data sets over a wide energy range. Both Saxon-Woods and double-folded real potentials have been used. In general, there is no requirement for energy dependence in either the real or imaginary potential for any of these targets, whether Saxon-Woods or folded real potentials are used. The main exception is ²⁸Si when energy dependence is required to simultaneously fit low-energy data and high-energy rainbow scattering with folded potentials. The degree to which the potentials are determined is discussed.