Measurement of optical losses and damage thresholds of multilayer coatings

A correlation between the absorption measured at λ = 514 and 1060 nm and the damage thresholds at λ = 1060 nm is established for evaporated dielectric multilayer stacks. In addition the diffused reflectance of the coatings was measured at λ = 633 nm by means of a Coblentz sphere.     

Computerized monitoring of air quality

The computerized air-control system in Upper Austria consists of a data acquisition and control equipment (DACE) located in Linz and nineteen peripheral units (PU) distributed in Upper Austria. The system is divided into two subsystems, each controlled by a process controller working in a real-time manner. Subsequently, the data obtained are processed with an off-line desktop computer to work out monthly or annual reports as well as forecasts of trends for the different measured air pollutants.     

Dietary fats and properties of endoplasmic reticulum: II. Dietary lipid induced changes in activities of drug metabolizing enzymes in liver and duodenum of rat

Rats were fed cholesterol, cacao butter, or olive oil diets to determine the effect of dietary lipids on the rate of drug biotransformation in the liver and duodenum. The cholesterol rich diet maintained the hepatic aryl hydrocarbon hydroxylase activity at the same level as did the standard diet. Rats fed olive oil and cacao butter diets showed lower hepatic aryl hydrocarbon hydrorylase activity. The p-nitroanisole 0-demethylase activity was doubled in hepatic microsomes of rats fed the high cholesterol diet when compared to rats fed the standard diet. The hepatic uridine diphosphate glucoronosyltransferase activity showed different patterns depending on the in vitro treatment of the microsomal membranes. If the enzyme activity was assayed from the native, untreated microsomes, an increase in the measurable uridine diphosphate glucuronosyl transferase activity was found in rats having cholesterol rich diet. After the in vitro activation of membrane-bound uridine diphosphate glucuronosyltransferase by trypsin, the increase in measurable activity was 10 fold in the group fed the standard diet, 6 fold in group fed cholesterol, 4 fold in group fed cacao butter, and 3 fold in group fed olive oil. Trypsin digestion of microsomes increased the measurable uridine diphosphate glucuronosyltransferase activity less in rats fed diets rich in neutral fats than those fed the standard diet. In the duodenal mucosa, lipid diets decreased the activities of drug hydroxylation and glucuronidation.     

K2GeTe4, ein pertelluridogermanat mit kettenstruktur

The new compound K₂GeTe₄ crystallizes in the monoclinic system, space group $\text{P}\text{2}{}_1\text{c}$ (No 14) with lattice constants a = 1270.3 ± 0.6 pm, b = 868.0 ± 0.4 pm, c = 982.9 ± 0.4 pm, ß = 104.8 ± 0.1°. In the structure there are GeTe₄-tetrahedra, connected by Te₂-bridges to infinite chains.     

Optimization of metallurgical variables in fracture prevention

The effect of metallurgical variables on the two most important crack growth mechanisms - stable crack growth by environmentally assisted cyclic crack growth and unstable crack growth by cleavage - in light water reactor pressure vessel steels is evaluated. The analyses are based on micromechanisms of fracture and sensitivity analysis, when applicable. Metallurgical variables considered are non-metallic inclusions and carbides as well as other parameters through their effects on yield strength and other mechanical properties.     

On the finite element analysis of crack and inclusion problems in elastic-plastic materials

A finite element method for treating plane strain, elastic-plastic boundary value problems is described. Constant strain triangular elements are used. The material is assumed to obey the von Mises yield criterion and its associated flow rule. In order to test the accuracy of the method the deformation of a pressurized circular tube is investigated and the results are compared with a finite-difference solution. The applicability of the method to problems involving two different materials is demonstrated for the case of a uniaxially loaded plate containing a circular inclusion. Finally some crack problems are analysed. Special attention is devoted to the case of small scale plasticity.     

A quasi-Newton method with Cholesky factorization

A quasi-Newton method for unconstrained minimization is presented, which uses a Cholesky factorization of an approximation to the Hessian matrix. In each step a new row and column of this approximation matrix is determined and its Cholesky factorization is updated. This reduces storage requirements and simplifies the calculation of the search direction. Precautions are taken to hold the approximation matrix positive definite. It is shown that under usual conditions the method converges superlinearly or evenn-step quadratic.     

Buchbesprechungen

Ohne Zusammenfassung     

Excluded volume effect on polymer films

Using Monte Carlo methods we have investigated the excluded volume effect on polymer melts in two dimensions. Investigating chain lengths of up to N = 59 at concentration $\text{c =}\text{5}\text{6}$, our results strongly support predictions made recently by de Gennes: (1) end-to-end distance and gyration radius exhibit Gaussian behaviour ∝ √N; (2) but their prefactors differ significantly from their random flight values; (3) in contrast to three-dimensional melts the chains are strongly segregated.