Über Reaktionen des P4S10 mit siliciumorganischen Verbindungen

Reactions of P₄S₁₀ with Organosilicon Compounds P₄S₁₀ ( 1 ) can be degraded with silicon-nitrogen compounds. 1 reacts with (CH₃)₃Si? N(CH₃)₂ ( 2 a ) and (CH₃)₃Si? N(C₂H₅)₂ ( 2 b ) to yield S?P[N(CH₃)₂]₂SSi(CH₃)₃ ( 3 a ) and ( 3 b ). By the reaction of 1 with [(CH₃)₃Si]₂S ( 4 ) S?P[S? Si(CH₃)₃]₃ ( 6 ) is formed in high yield. (C₆H₅PS₂)₂ ( 7 ) was used as a model to investigate the course of the reaction. This leads to C₆H₅P(S)? [N(CH₃)₂]SSi(CH₃)₃ ( 9 ) and C₆H₅P(S)[SSi(CH₃)₃]₂ ( 10 ). The reaction mechanism will be discussed. The n.m.r. data and mass spectra are reported.     

Finite versus small strain discrete dislocation analysis of cantilever bending of single crystals

Plastic size effects in single crystals are investi-gated by using finite strain and small strain discrete dislo-cation plasticity to analyse the response of cantilever beam specimens. Crystals with both one and two active slip sys-tems are analysed, as well as specimens with different beam aspect ratios. Over the range of specimen sizes analysed here, the bending stress versus applied tip displacement response has a strong hardening plastic component. This hardening rate increases with decreasing specimen size. The hardening rates are slightly lower when the finite strain discrete disloca-tion plasticity (DDP) formulation is employed as curving of the slip planes is accounted for in the finite strain formulation. This relaxes the back-stresses in the dislocation pile-ups and thereby reduces the hardening rate. Our calculations show that in line with the pure bending case, the bending stress in cantilever bending displays a plastic size dependence. How-ever, unlike pure bending, the bending flow strength of the larger aspect ratio cantilever beams is appreciably smaller. This is attributed to the fact that for the same applied bend-ing stress, longer beams have lower shear forces acting upon them and this results in a lower density of statistically stored dislocations.     

High resolution photon stimulated desorption spectroscopy of solid nitrogen by resonant N 1s core level excitation

Photon stimulated desorption (PSD) spectra of ions (N⁺, N⁺ ₂, and N²⁺) by N 1s 1 _g and N 1s Rydberg level excitations have been recorded from solid nitrogen for different polarization and detection conditions, and compared with electron yield data. Vibrational fine structure is clearly resolved also in photon stimulated desorption (PSD) spectra; its details depend on layer preparation, but also on the type of signal. Detailed evaluation should allow conclusions on the nature and the dynamics of the process of bond breaking and on the influence of the surroundings on it. Exploiting alignment effects by properly setting polarization and detection angles, symmetries of electronic excited states can be well analysed even for samples consisting of randomly oriented molecules.     

Deformation and failure kinetics of polyvinylidene fluoride: Influence of crystallinity

The present study investigates the effect of processing conditions on the yield kinetics, such as rate dependence of the yield stress and creep rupture, of polyvinilidene fluoride. Samples were compression molded with cooling rates varying from 100°C/s to 0.5°C/min, or isothermally crystallized at temperatures varying from 20 to 120°C. Deformation kinetics were studied over a wide range of strain rates and temperatures. It is shown that for all conditions the yield response is well represented by the Ree–Eyring model. Moreover, the activation volumes and activation energies are independent from the processing conditions. The effect of processing is fully covered by a simple relationship between the rate factors and the degree of crystallinity. Subsequently, the versatility of this relationship is demonstrated by experimental validation.     

Effective sample size: Quick estimation of the effect of related samples in genetic case-control association analyses

Affected relatives are essential for pedigree linkage analysis, however, they cause a violation of the independent sample assumption in case-control association studies. To avoid the correlation between samples, a common practice is to take only one affected sample per pedigree in association analysis. Although several methods exist in handling correlated samples, they are still not widely used in part because these are not easily implemented, or because they are not widely known. We advocate the effective sample size method as a simple and accessible approach for case-control association analysis with correlated samples. This method modifies the chi-square test statistic, p-value, and 95% confidence interval of the odds-ratio by replacing the apparent number of allele or genotype counts with the effective ones in the standard formula, without the need for specialized computer programs. We present a simple formula for calculating effective sample size for many types of relative pairs and relative sets. For allele frequency estimation, the effective sample size method captures the variance inflation exactly. For genotype frequency, simulations showed that effective sample size provides a satisfactory approximation. A gene which is previously identified as a type 1 diabetes susceptibility locus, the interferon-induced helicase gene (IFIH1), is shown to be significantly associated with rheumatoid arthritis when the effective sample size method is applied. This significant association is not established if only one affected sib per pedigree were used in the association analysis. Relationship between the effective sample size method and other methods - the generalized estimation equation, variance of eigenvalues for correlation matrices, and genomic controls - are discussed.