Multipass cell design for Stark-modulation spectroscopy

A multipass cell for absorption measurements with an additionally applied homogeneous electric field for Stark effect measurements is described. The configuration is based on two ring mirrors, where the laser beam propagates between two nested cylindrical-wall electrodes. The total optical path length achieved is 40 m. The beam pointing stability of this setup is investigated and compared to a confocal-type Herriott cell of the same base length, employing numerical simulations. The exit beam pointing stability is found to be very good. The response measurements show fast exchange times, which agree well with theoretical values.     

Progress report on hair keratin research

Evidence is given for the progress in hair keratin research by bringing out four examples from the recent hair science literature. 1 Kon et al. [1] published a new method of solubilization and fractionation of the matrix and the microfibril proteins and found a significant decrease in the 'intact' microfibril keratin at the tip end of permed hair. 2 Contrary to the previous view of the existence of four major and one minor hair keratin pair, Langbein et al. [2, 3] showed that there are nine type I hair keratins and six type II hair keratins and drew up a two-dimensional catalogue of human hair keratins. 3 To collectively describe the extremely complex expression pattern of human type I and type II hair keratins in the hair follicle, Langbein et al. [2, 3] have summarized the corresponding RNA expression profiles of the various hair keratins schematically. 4 Contrary to the previous assignment of keratins exclusively to the microfibrils in the cortex, the mRNA expression studies of Langbein et al. [2, 3] implied that any hair cuticle cell leaving the living cell compartment contains four different hair keratins.     

Ultrasonic cutting of foods: Effects of excitation magnitude and cutting velocity on the reduction of cutting work

The effects of vertical cutting velocity and the magnitude of ultrasonic excitation on the reduction of the work necessary to separate various food materials were investigated. Generally, cutting work increased with increasing cutting velocity but, at each particular cutting velocity, decreased with increasing magnitude of the ultrasonic excitation of the cutting tool. Interactions between cutting velocity and the maximum vibration speed at the cutting edge, which is determined by both excitation amplitude and excitation frequency, are significant. Depending on the food under action, the relative amount of cutting work reduction is either affected by the maximum vibration speed or, additionally, by vertical cutting velocity. No distinct effects of the excitation frequency (20 or 40 kHz) were observed.

Industrial relevance

Ultrasonic cutting is used in the food industry, especially for the separation of products consisting of layers with different rheological properties to achieve minimally damaged cut surfaces. The results of the study may be useful for selecting operational variables (cutting velocity, excitation amplitude) during cutting to achieve a controlled reduction of the cutting work.     

Lorenz Function of Bi2Te3/Sb2Te3 Superlattices

Combining first-principles density functional theory and semiclassical Boltzmann transport, the anisotropic Lorenz function was studied for thermoelectric Bi₂Te₃/Sb₂Te₃ superlattices and their bulk constituents. It was found that, already for the bulk materials Bi₂Te₃ and Sb₂Te₃, the Lorenz function is not a clear function of charge carrier concentration and temperature. For electron-doped Bi₂Te₃/Sb₂Te₃ superlattices, large oscillatory deviations of the Lorenz function from the metallic limit were found even at high charge carrier concentrations. The latter can be referred to quantum well effects, which occur at distinct superlattice periods.     

Relations between enzyme activities connected with energy metabolism and parameters of food energy utilization in young and adult rats. Part 2. Enzyme activities related to alpha-glycerophosphate shuttle in various tissues

The possible significance of food composition connected with the alpha-glycerophosphate (alpha GP) shuttle, a putative metabolic pathway of energy dissipation, was investigated at the level of enzyme activities. Liver, adipose tissue, slow-twitch and fast-twitch muscle of weaned male Wistar rats fed ad libitum for seven and for forty weeks a normal-protein (NP), a low-protein (LP), and a high-fat (HF) diet were examined. No striking dietary influences on cytosalic (NAD-linked glycerophosphate dehydrogenase, glyceraldehyde-phosphate dehydrogenase) and mitochondrial (succinate dehydrogenase, cytochrome c oxidase) enzyme activities could be detected, but mitochondrial alpha-glycerophosphate dehydrogenase (m-GPDH) showed an about twofold increase of its activity in the liver of LP-fed animals after seven weeks. A relationship between the "gross efficiency of food energy utilization" and tissue m-GPDH levels could not be established in general. The proposed inducing effect of a LP diet on the magnitude of the GP shuttle observed in the liver of young and adult rats seems to be interconnected reciprocally with the degree of metabolic energy dissipation only under the conditions of growth. The calculated capacities of the alpha GP shuttle are compatible with the assumption of its function as an energy dissipating pathway which is restricted in its magnitude.     

Detection and resolution of normative conflicts in multi-agent systems: a literature survey

Multi-agents systems are composed of autonomous and possibly heterogeneous software agents that act according to their own interests. Some coordination mechanism must be adopted to ensure a proper functioning of the whole system. Norms can be viewed as a powerful means to regulate and influence the behaviour of the agents by specifying, for instance, obligations, permissions, or prohibitions in a given context. A critical issue that must be considered in a system governed by multiple norms is the possible existence of normative conflicts. A conflict between norms is a situation in which the fulfilment of a norm causes a violation of another one. In this paper, we present several techniques that have been proposed to detect and resolve normative conflicts in multi-agent systems. Our aim is to organize the literature, present a classification of the techniques found, and provide a means to compare alternative approaches dealing with normative conflicts.     

Alternative Anschlußbewehrung für im Fundament eingespannte Stützen und Wände

Alternative Detail of the Connection Reinforcement for Columns and Walls fixed at the Footing The paper suggests an alternative detail for the connection reinforcement transferring the bending moments at the base of fixed columns and walls to their foundation. In contrast to the typically used interlocking L‐shaped starter bars, the suggested connection reinforcement is in the form of U‐bars, thus greatly improving the constructability. The performance of U‐shaped starter bars was experimentally investigated in two test series and by comparative parameter studies using nonlinear finite element analyses. The results of these investigations are presented and discussed herein.     

Dielectrometry measurements of moisture dynamics in oil-impregnatedpressboard

In oil-impregnated pressboard of medium and low humidity the complex dielectric spectrum's shape and amplitude do not change with variations in temperature and moisture content, but only shift in frequency. Thus it is possible to create a `universal' curve, with appropriate temperature correction factors, which can be used to extract information about the moisture dynamics of solid transformer insulation from dielectrometry measurements. To create the universal curve, measurements are taken with the material placed in a parallel-plate structure whose complex impedance is measured. To measure spatial distributions of dielectric properties, imposed ω-k (frequency-wavenumber) dielectrometry is used, where a set of interdigitated electrodes on one surface of the material cause the electric field to have a limited depth of penetration into the dielectric, proportional to the electrode spacing. Measurements using the parallel-plate methodology establish a mapping of the dielectric spectrum of EHV-Weidmann HIVAL pressboard impregnated with Shell Diala A transformer oil, as a function of temperature and water content. This mapping is then used to determine spatial moisture profiles in pressboard in other experiments which make use of a three-wavelength interdigitated sensor