Assignment of ring size in isopropylidene acetals by 13C N.M.R.

Cyclic isopropylidene acetals containing 5,6 and 7-membered rings can be distinguished by measurement of the ¹³C chemical shifts of the acetal carbon and the methyl groups.     

Glaspunkte von textilen Polyamidfasern. II. Beziehungen zwischen Glaspunkt und Anf?rbbarkeit

Ohne Zusammenfassung     

Use of non-aqueous solvents in glassware calibrated to deliver water

The quantity of non-aqueous solvent delivered by a transfer pipette calibrated to deliver water was investigated. With the solvents tested the volume delivered was within 2 parts per thousand of the volume of water delivered, and this difference was less than the permitted tolerance for the pipette.     

Annealing experiments on drawn nylon 66 fibers

Drawn, nylon 66 yarns have been annealed in oil under relaxed conditions. Shrinkage and tensile modulus were measured and the yarns were examined by wide- and small- angle x-ray diffraction. The results are similar to those obtained by Dismore and Statton, but there are significant differences. The data indicate a model for a drawn nylon 66 fiber in which substantial amounts of folds remain.     

Structure of 72,74Se at high spin

Lifetimes of high spin states up to { }=22⁺ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in ^{72, 74}Se. The Q _t values derived from these measurements indicate that prolate shape stabilizes for ⁷²Se, while a triaxial shape develops for ⁷⁴Se at higher spins. Comparison of the observed trend in Q _t with spin for ^{72, 74}Se with that of the corresponding kryptones isotones emphasizes the stability provided by N=38 prolate shell gap even at high rotational frequency.     

Solid State C NMR of 30-Crown-10 Ether and 30-Crown-10.4H2O

The ¹³C NMR solution spectra of 30-crown-10 ether and its tetrahydrate show only one resonance at all accessible temperatures. In contrast, the solid state ¹³C NMR spectrum of the 30-crown-10.4H₂O shows two resonances in the ratio of 4:1, separated by 1.2 ppm. In the case of 30-crown-10 itself, six resolvable ¹³C resonances in the ratio of 4:1:1:2:1:1 are observed in the solid with an overall chemical shift dispersion of 5 ppm. The remarkably different spectral behavior of these two systems in the solid state is discussed in terms of the torsional environments of the crystallographically unique carbons and the results of GIAO calculations of isotropic ¹³C shieldings for simpler model compounds. Results of dipolar dephased ¹³C CPMAS spectra indicate that 30-crown-10 does not undergo a large amplitude molecular motion, in contrast to earlier results for 18-crown-6. Only a small amount of residual intensity is found in the dipolar dephased spectrum of 30-crown-10.4H₂O, indicating that it also is relatively rigid in the solid.     

Differential laser-induced perturbation spectroscopy using a deep-ultraviolet excimer laser

Here we demonstrate a unique optical sensing scheme based on deep-UV photochemical perturbation in combination with difference spectroscopy. Applying a sequence of optical probing, UV-laser-induced perturbation, and repeat optical probing coupled with difference spectroscopy provides a new spectral signature. We show a selective (sevenfold difference) optical response using a fluorescence probe for binary mixtures of organic dyes, and generate complementary spectral information derived from Raman scattering of the dipeptide glycine-glycine. We further extend the methodology to fluorescence-based imaging of an organic matrix.