NQR on Gallium Single Crystals for Absolute Thermometry at Very Low Temperatures

It is shown that NMR/NQR-thermometry on Ga single crystals can serve the need of absolute thermometry in a temperature range from below 20 K to above 1 mK. Thus, the sensitive range includes all phase transition temperatures around 1 mK of solid and fluid ³ He, a necessity for an extension of the ³ He-melting-pressure temperature scale towards lower temperatures. The experiments were performed in magnetic fields of 50 to 200 mT and at temperatures down to 200 K using single rf-pulses. Special care was taken for the orientation of the magnetic field with respect to crystal orientation which was obtained by in-situ pulsed NMR-experiments. It has been shown that in the investigated parameter range nonlinear effects in NMR due to high spin alignment had no significant influence. In pulsed NMR as well as in specific heat experiments it could be shown that spin-spin interactions are only weak in Ga and do not influence nuclear paramagnetism, at least at temperatures above 100 K. The advantages of using Ga instead other elements for population difference thermometry are discussed.     

Identifying clinical syndromes in a community sample of elderly persons.

By a strategy suggested by E. H. Uhlenhuth et al (1983), Diagnostic and Statistical Manual of Mental Disorders (DSM-III) referenced syndrome classifications were derived on the basis of the Hopkins Symptoms Checklist—42 scores of 1,131 elderly community residents. Overall syndrome prevalence rates were consistent with other epidemiologic data: 3.9% for depression, 1.0% for agoraphobia-panic, 2.6% for other phobia, and 6.9% for anxiety. Prevalence rates reflected expected sex differences and showed an age trend for other phobias. Considerable comorbidity among syndromes was observed. The association of the syndromes with patterns of psychosocial risk factors, prior diagnoses, and medication suggests that some but not all of the identified syndromes reflect clinically relevant classifications. If further developed, syndrome classifications based on self-report scales can provide inexpensive and clinically relevant measures of caseness. Required refinements of this approach are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Combined cathodoluminescence and X-ray analysis of paint pigments

The suitability of cathodoluminescence (CL) measurements for differentiating between different paint pigments is demonstrated with an example of a combined energy-dispersive X-ray (EDX) and CL analysis of different zinc oxide (ZnO) pigments in a paint fragment where the EDX spectra are virtually identical, but where the CL spectra show significant differences. Consequently, it is possible to distinguish different pigments on the basis of CL spectra and monochromatic CL micrographs.     

Melting behavior of polypropylene fibers studied by differential scanning calorimetry

Polypropylene fibers produced in a compact-spinning process were studied by differential scanning calorimetry (DSC). With unrestrained fibers, the onset of melting increases with decreasing draw ratio, increasing M_w/M_n, decreasing extrusion temperature, increasing annealing ratio, and increasing draw-down ratio. These trends are discussed in terms of restraints and reorganization. The onset of melting is shifted to lower temperatures as the heating rate increases for all combinations of material and processing parameters, indicating suppressed reorganization. At low draw ratios, the height and width of the endotherm are affected by the spinline stress, and a secondary peak or shoulder is observed on the high temperature side of the main peak. The magnitude of the secondary peak increases with decreasing M_w/M_n, increasing draw ratio, decreasing draw-down ratio, and decreasing heating rate, but its position mainly depends on the heating rate. This indicates that the secondary peak may be due to the melting of structures that have been reorganized during the heating scan. As the draw ratio increases, the melting regime broadens, especially towards lower temperatures, and several maxima emerge on the DSC curve. Reorganization and shrinkage during heating may explain these observations. © 1995 John Wiley & Sons, Inc.     

Microstructure and mechanical properties of rapidly solidified Fe-25%Cr-5%Al ribbons produced by planar flow casting

Catalyst substrate foils of the highly oxidation resistant Fe-25Cr-5Al alloy (mass contents in %) with a thickness ranging from 40 to 180 μm have been produced by planar flow casting. The rapidly solidified ribbons showed a monophase ferritic microstructure of columnar grains. The grain size determined over a section parallel to the ribbon wheel side ranged from 5 μm for the thin ribbons (40 μm) to 18 μm for the thicker ones {180 μm). This anisotropic columnar solidification microstructure exhibits a strong <100> fiber texture, with the fiber axis nearly perpendicular to the plane of the ribbon. The position of the maximum in the pole figure was tilted from the center point toward the casting direction. Results of uniaxial tensile tests showed that only the yield stress data of the ribbons in the as-cast condition are reproducible, whereas the ultimate tensile strength and the elongation to failure data show a wide scatter band. The fracture mode exhibits ductile features such as glide bands and dimples.     

Modeling and animation of facial expressions based on B-Splines

This paper describes a technique for the automatic adaptation of a canonical facial model to data obtained by a 3D laser scanner. The facial model is a B-spline surface with 13×16 control points. We introduce a technique by which this canonical model is fit to the scanned data and that takes into consideration the requirements for the animation of facial expressions. The animation of facial expressions is based on the facial action coding system (FACS). Using B-splines in combination with FACS, we automatically create the impression of a moving skin. To increase the realism of the animation we map textural information onto the B-spline surface.     

Reductive silylation and alkylation of phthalimides

Preparative electrochemical reduction of N-methylphthalimide in dry acetonitrile and in the presence of dimethylsulfate or trimethylchlorosilane lead to bis-lactams by dimerization at the carbonyl group. 1, 3-Bis-trimethylsilyloxy-2-methylisoindole is formed instead using a large excess of silylating agent. An analogous isoindole derivative is obtained from reduction of N-phenylphthalimide. A mechanism accounting for the formation of one or two electron products under different alkylating conditions is discussed.