Structure formation in systems involving poly(ethylene oxide) and small molecules

The structure of the intercalates in which poly(ethylene oxide), PEO, is the host component and para-disubstituted benzenes are the guest molecules is completely elucidated by X-ray diffractometry, polarized FTIR spectrography, and calorimetry. It is shown that the association of these molecules results from the adaptation of the shape of their external surfaces. On this basis the possibility of formation of structure involving PEO and small molecules is discussed.     

An investigation of hemibenzopinacolate radicals used in the synthesis of block-copolymers: ESR measurements and semiempirical calculations

Hemibenzopinacolate radicals may be incorporated in a polymer chain and the latter used as a macromolecular initiator. Kinetics of polymerization are strongly dependent on the substitution of the pinacolate. A large family of substituted (CH₃)₃SiOC(C₆H₅)₂ radicals has been synthesized and studied by electron spin resonance (ESR) and semiempirical molecular orbital calculations. ESR spectra are well resolved and, except for one derivative, allow an unambiguous determination of the hyperfine coupling splitting (HFS) constants. The ground state properties have been calculated within different approximations, namely MNDO, AM1 and PM3 for the geometry optimization and INDO for spin density. Geometries obtained within AM1 and PM3 approximations are satisfactory. The HFS constants evaluated using McConnell type relations and spin densities are in a quite good agreement with the experimental ones. It turns out that the effect of substitution on kinetics of polymerization cannot be attributed to any drastic change in the charge distribution.     

Glyphosate–Exonuclease Interactions: Reduced Enzymatic Activity as a Route to Glyphosate Biosensing

N-phosphonomethyle-glycine (glyphosate) is the most widely used pesticide worldwide due to its effectiveness in killing weeds at a moderate cost, bringing significant economic benefits. However, owing to its massive use, glyphosate and its residues contaminate surface waters. On site, fast monitoring of contamination is therefore urgently needed to alert local authorities and raise population awareness. Here the hindrance of the activity of two enzymes, the exonuclease I (Exo I) and the T5 exonuclease (T5 Exo) by glyphosate, is reported. These two enzymes digest oligonucleotides into shorter sequences, down to single nucleotides. The presence of glyphosate in the reaction medium hampers the activity of both enzymes, slowing down enzymatic digestion. It is shown by fluorescence spectroscopy that the inhibition of ExoI enzymatic activity is specific to glyphosate, paving the way for the development of a biosensor to detect this pollutant in drinking water at suitable detection limits, i.e., 0.6 nm .     

Contributions to Forming and Analytical Investigations of Solutions of Cellulose and Cellulose Derivatives – A Research and Development Topic of the TITK eV

Modification, forming and analytical characterisation of cellulose and cellulose solutions represents one of the most important research topics of the Thuringian Institute for Textiles and Plastics Research (TITK). The presentation provides information on the current capabilities of the institute and on the analytical methods developed in these fields.     

Modeling and Numerical Simulation of Cavitation for Compressible Liquid Flow

A method for the numerical simulation of cavitation phenomena based on the thermodynamic properties of liquid and steam is described. Thereby, a homogeneous cavitation model using a fully compressible discretization technique is considered. The ability of the scheme is proven by numerical experiments.