Dynamics of Interacting OH– and OD– Ions in KCl

OH^– and OD^– defects are known to form rotational tunneling systems in KCl host crystals. We have studied the complex dielectric susceptibility of KCl doped with different concentrations of OH^– and OD^– in a wide range of frequencies and temperatures. Our main result is that there is a transition from coherent single ion tunneling at low defect concentration to an incoherent tunneling motion at high defect concentrations. In addition, we have studied the thermally activated motion of pairwise coupled hydroxide ions in an attempt to obtain information on the microscopic configurations of the different pairs contributing to the dielectric loss. PACS numbers: 61.72.Ji, 77.22-d, 78.30.Ly     

Low-power digital filtering using approximate processing

We present an algorithmic approach to the design of low-power frequency-selective digital filters based on the concepts of adaptive filtering and approximate processing. The proposed approach uses a feedback mechanism in conjunction with well-known implementation structures for finite impulse response (FIR) and infinite impulse response (IIR) digital filters. Our algorithm is designed to reduce the total switched capacitance by dynamically varying the filter order based on signal statistics. A factor of 10 reduction in power consumption over fixed-order filters is demonstrated for the filtering of speech signals     

The determination of protein hydrophobicity. 1. Determination of the hydrophobicity of selected cereal and milk proteins using their sodium dodecyl sulfate binding capacities]

The sodium dodecylsulphate (SDS) binding capacities of secalin, gliadin and gluten in the presence of a very low SDS concentration were determined and compared to the SDS binding capacities of bovine serum albumin (BSA), beta-lactoglobulin, ovalbumin und beta-casein. The SDS binding capacities of endosperm proteins determined in phosphate buffer (pH 6.0) are very low. Only 0.6 microgram .. 0.8 microgram SDS were bound to 500 micrograms of the proteins. This low SDS binding capacities do not correlate with the expected hydrophobicity of these proteins. In comparison, 500 micrograms of ovalbumin, beta-lactoglobulin and BSA each bind 0.5, 5.9 and 13.5 micrograms SDS, respectively. According to literature the SDS binding capacities of these proteins are in correlation with the surface hydrophobicity determined with cis-parinaric acid using the fluorescence probe method. The SDS binding capacities of endosperm proteins increased in the presence of 0.1 N acetic acid and consequently 6.2 micrograms .. 6.9 micrograms SDS were bound to 500 micrograms of the corresponding proteins. beta-casein described as a highly hydrophobic protein binds only 0.9 micrograms SDS to 500 micrograms of it in phosphate puffer (pH 6.0) and 1.2 micrograms SDS in 0.1 N acetic acid, respectively.     

An Eigen-Analysis of Compact Antenna Arrays and Its Application to Port Decoupling

Placing the radiators of antenna arrays closer than aggravates the problem of power mismatch. Based on efficiency considerations, a general analysis of this effect is presented, putting forward a simple tool to quantify, compare, and optimize the performance of antenna arrays. This analysis is not restricted with respect to the number of radiators or the degree of compactness. In order to improve power matching, a systematic approach for the design of lossless decoupling and matching networks based on 180 directional couplers is suggested for up to eight radiators. Implications of network losses, which have not yet received appropriate attention by researchers in the past, will be analyzed and discussed by means of a manufactured three-element prototype array.     

Quantitative measurement of gas hold-up distribution in a stirred chemical reactor using X-ray cone-beam computed tomography

Cone-beam type X-ray computed tomography (CBCT) is a potential method to measure three-dimensional phase distributions in vessels. An example for that is the measurement of gas profiles in stirred chemical reactors. Such data are highly valuable for the assessment and evaluation of chemical processes, for optimisation of the reactor and stirrer design, and for evaluation of computational fluid dynamics codes used to model the fluid flow and heat transfer in reactive systems. However, there are considerable difficulties for accurate quantitative measurements due to beam hardening and radiation scattering effects. In a theoretical and experimental work we have investigated the non-linear effects of both physical phenomena and developed a suitable measurement setup as well as calibration and software correction methods to achieve a highly accurate measurement of void fraction profiles with CBCT.