Ein neuer Weg zur quantitativen Erfassung der Vorgänge beim kontrollierten Walzen

Qualitative Ableitung der Größe ?addierte Endverformung“ und ihre quantitative Beschreibung über temperaturabhängige Additionskoeffizienten. Vorausberechnung von Streckgrenze und Festigkeit aus dem Stichplan. Berechnung eines Übergangspunktes der Kristallinität und hieraus Konstruktion der Kerbschlagzähigkeitskurve.     

Effects of leader behaviors on subordinate performance and satisfaction: A laboratory experiment with student employees.

Four groups of 12 participants were hired to code videotaped group interactions using the Bales coding system (R. F. Bales, 1950). Each of the 4 groups experienced different leader behaviors of either high or low consideration in conjunction with either high or low initiating structure. Results indicate that subordinates did not perceive the leader manipulations as different but that these manipulations caused differences in quantity and quality of work. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth of Salmonella enteritidis in yolk from eggs laid by immunized hens

After hyperimmunization of laying hens with Salmonella enteritidis, antibodies can be found in egg yolks. This study was conducted to ascertain whether the growth of S. enteritidis would be suppressed in the presence of antibodies contained in egg yolk. Specifically pathogen-free (SPF)-laying hens were immunized with S. enteritidis; eggs were collected, the yolk was separated and the concentration of S. enteritidis antibodies was determined quantitatively by using the enzyme-linked immunosorbent assay (ELISA), the radial immunodiffusion and the bicinchoninic acid protein assay. Then, the yolk was inoculated with approximately 10, 100 or 1000 S. enteritidis cells/ml and incubated at 15, 20 and 30 degrees C for 0, 2, 6 and 24 h. The growth of organisms in each yolk was examined, and the generation times were calculated. The egg yolk from nonimmunized hens served as negative control. The highest level of antibody concentration was found in the hyperimmunized group. There was no difference in the generation times of S. enteritidis between the antibody-positive yolk and the negative yolk at the three different incubation temperatures. The results suggest that antibodies in the yolk do not influence the growth of S. enteritidis, even if the hens are highly immunized.     

Time-dependent behavior of fine-grained model material in resonant column experiments

Cyclic shear experiments with saturated and dry fine-grained corundum powder, i.e. -Al₂O₃ particles, have been conducted in a resonant column device. After an increase of total pressure the shear stiffness showed a slight decrease and a subsequent increase with time. The equivalent viscous damping ratio followed an opposite trend. The increase of shear stiffness with time did not stop after the end of primary consolidation, which cannot be explained with the slight reduction of void ratio during secondary consolidation. Stiffening of grain contacts through different dissolution-precipitation mechanisms and creep at particle contacts can explain the increase of shear stiffness with time, which has also been observed in natural soils by other researchers. Smaller rates of stiffness increase of dry samples support the idea of dissolution-precipitation mechanisms in the pore water. Higher rates for samples with smaller particles show an effect of surface-to-volume ratio.The study described in this paper was sponsored by the German Research Council (DFG), Research Group FOR 371-2. The support is gratefully appreciated.We would like to thank Professor Gudehus for many interesting discussions and valuable advice.We thank the Institute of Mechanical Process Engineering and Mechanics and the Laboratory for Electron Microscopy, University of Karlsruhe, for providing the electron micrographs and the Institute for Ceramics in Mechanical Engineering for the grain size distribution.     

Two software tools for plane-wave scattering on nonspherical particles in the German Aerospace Center's Virtual Laboratory

We present the methodological background, the range of applicability, and the on-line usage of two software packages, MIESCHKA and CYL, which we have developed for light-scattering analysis on nonspherical particles. MIESCHKA solves Maxwell's equations in a rigorous way but is restricted to axisymmetric geometries, whereas CYL is an approximation for finite columns with nonspherical cross sections. We have established an easy on-line access to both of these programs through the Virtual Laboratory. Its generic software infrastructure was designed to simplify the web-based usage and to support the intercomparability of scientific software.     

Impressions of groups as a function of the stimulus values of their individual members.

Beginning with a model of social perception in which the perceiver is assumed to operate according to the conventional canons of statistical inference, it was hypothesized that trait judgments of groups of individuals represented by facial photographs would match the mean values of these photographs judged individually and that confidence and the amount of information required before a judgment is reported will vary inversely with the variance in the set of photographs comprising the group, and directly with the significance of the judgment for the judge. Using different procedures and measures of the dependent variables, 2 experiments were performed which agreed in supporting the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface chemical heterogeneity of bacteriogenic iron oxides from a subterranean environment

This study quantifies the surface chemical heterogeneity of bacteriogenic iron oxides (BIOS) and its end-members (2-line ferrihydrite and intermixed intact and fragmented bacteria). On a dry weight basis, BIOS consisted of 64.5 +/- 1.8% ferrihydrite and 34.5 +/- 1.8% organic matter. Enrichment of Al, Cu, Cr, Mn, Sr, and Zn was shown in the solid versus the aqueous phase (1.9 < log Kd < 4.2). Within the solid-phase Al (69.5%), Cu (78.7%), and Zn (77.9%) were associated with the bacteria, whereas Cr (59.8%), Mn (99.8%), and Sr (79.4%) preferred ferrihydrite. Acid-base titration data from the BIOS and bacteria were fitted using FOCUS pKa spectroscopy. The bacteria spectrum with pKa's of 4.18 +/- 0.37, 4.80 +/- 0.54, 6.98 +/- 0.45, and 9.75 +/- 0.68 was similar to discrete and continuous spectra for intact and fragmented bacteria. The BIOS spectrum recorded pKa's of 4.27 +/- 0.51, 6.61 +/- 0.51, 7.89 +/- 1.10, and 9.65 +/- 0.66 and was deconvoluted to remove overlapping binding site contributions from the bacteria. The resulting residual iron oxide spectrum coincided with discrete MUSIC spectra for goethite and lepidocrocite with pKa values of 4.10 +/- 0.43, 6.53 +/- 0.45, 7.81 +/- 0.76, and 9.51 +/- 0.68. Surface site density analysis showed that acidic sites (pKa < 6) were contributed by the bacteria (37%), whereas neutral sites (6 < pKa < 8) were characteristic of the iron oxide fraction (35%). Basic sites (8 < pKa) were higher in the bacteria (57%), than in the BIOS (44%) or iron oxide fractions (47%). This analysis suggested a high degree of bacterial group masking and a similarity between the BIOS and goethite surface reactivity. An understanding of the BIOS surface chemical heterogeneity and inherent proton and metal binding capacity was obtained through the use of FOCUS apparent pKa spectroscopy.