Separation and quantification of heart and liver phospholipid classes by high-performance liquid chromatography using a new light-scattering detector

This work describes a one-step separation of rat tissue phospholipid classes by high-performance liquid chromatography (HPLC) using a silica column and a new light-scattering detector (LSD). Complete separation of phosphatidylcholine, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylserine, sphingomyelin, lysophosphatidylethanolamine, and lysophosphatidylcholine was obtained. Direct quantification was achieved after detector calibration for each phospholipid class. The detector response was shown to be linear within the ranges used. The LSD results agreed well with those obtained by phospholipid phosphorus assay. The present method was applied to rat heart and rat liver phospholipid analysis.     

Determination of the composition of copolyester based on glycolide and dℓ-lactide by chromatography

Conclusions A procedure has been developed for determining the composition of copolyesters based of glycolide and dl-lactide.The procedure has reasonable analytical accuracy and can be used for operative analytical control in copolymer synthesis.Translated from Khimicheskie Volokhna, No. 4, pp. 59–61, July–August, 1989.     

Fire hazard properties of viscose fibre dusts

Conclusions The fractional composition of viscose fibre dust formed in the packaging division has been investigated.A quantitative determination of the combustible dust accuulated in the manufacturing packaging site has been carried out.It has beem shown that the viscose fibre dust fraction with a particle size less than 0.800 mm presents an explosion hazard, but the content of explosive dust does not exceed 6.1% of the total amount of dust. Dust which has not been separated into fractions presents no explosion hazard.To ensure safety from fire in viscose fibre packaging locations, it is necessary to use a mechanized dust-collection system.Translated from Khimicheskie Volokna, No. 6, pp. 44–45, November–December, 1989.     

Cyclic Fatigue-Crack Propagation in Magnesia-Partially-Stabilized Zirconia Ceramics

The subcritical growth of fatigue cracks under (tension-tension) cyclic loading is demonstrated for ceramic materials, based on experiments using compact C(T) specimens of a MgO-partially-stabilized zirconia (PSZ), heat-treated to vary the fracture toughness K _c from ∼3 to 16 MPa·m^1/2 and tested in inert and moist environments. Analogous to behavior in metals, cyclic fatigue-crack rates (over the range 10⁻¹¹ to 10⁻⁵ m/cycle) are found to be a function of the stress-intensity range, environment, fracture toughness, and load ratio, and to show evidence of fatigue crack closure. Unlike toughness behavior, growth rates are not dependent on through0-thickness constraint. Under variable-amplitude cyclic loading, crack-growth rates show transient accelerations following low-high block overloads and transient retardations following high-low block overloads or single tensile overloads, again analogous to behavior commonly observed in ductile metals. Cyclic crack-growth rates are observed at stress intensities as low as 50% of K _c , and are typically some 7 orders of magnitude faster than corresponding stress-corrosion crack-growth rates under sustained-loading conditions. Possible mechanisms for cyclic crack advance in ceramic materials are examined, and the practical implications of such "ceramic fatigue" are briefly discussed.     

Response of pocket gophers (Thomomys talpoides) to an operational application of synthetic semiochemicals of stoat (Mustela erminea)

This paper reports on laboratory bioassays and a large-scale field trial of synthetic mustelid anal-gland compounds in controlled-release devices designed for operational application to burrow systems of northern pocket gophers (Thomomys talpoides). The field study was conducted in an apple orchard in the Okanagan Valley of British Columbia. In laboratory bioassays, a 1∶1 mixture of 2-propylthietane and 3-propyl-1,2-dithiolane from the stoat (Mustela erminea) and 3,3-dimethyl-1,2-dithiolane from the ferret (M. putorius), dispensed in clay pellets (activated alumina), produced a significant avoidance response by gophers. All resident gophers were permanently removed from 4-ha control and treatment blocks prior to placement of stoat odor in burrows. As indexed by soil mounds, significantly fewer gophers colonized the treatment (40) than the control (68) removal area during a 5.5-month overwinter experiment. There was also a significant difference when comparing the number of mounds between pre-(79) and posttreatment (40) censuses. In addition, most gopher activity tended to occur on the perimeter of the treatment block. Abundance of gophers showed little difference between additional 4-ha control and treatment blocks where gophers had not been removed. The results of this study provide an alternative technique to toxicants for pocket gopher control on forest and agricultural land.     

Selective formation of 2-methyl-2-butene and 2-methyl-1-butene: Operating conditions and kinetic analysis

The effect of linear gas velocity, catalyst particle size, reaction temperature, space time, etc. on the dehydration of amyl alcohols (from fusel oil) was studied, using as catalyst a pre-treated bentonite. The analysis of the kinetic data, using Hougen-Watson type models, gives as the best model one in which amyl alcohol is absorbed on two active sites, the reaction rate being determined by the surface reaction of absorbed species.     

Chromium diffusion in gallium arsenide

Chromium diffusion in GaAs was studied by measuring the thickness of high-resistivity layers formed during diffusion of chromium (a deep acceptor) in n-GaAs. The dependence of the chromium diffusivity in GaAs on the temperature, arsenic-vapor pressure, conductivity type, and carrier density was determined. The temperature dependence of the diffusivity is described by the Arrhenius equation with the parameters D₀=8×10⁹ cm²/s and E=4.9 eV. The dependence of the diffusivity on the arsenic-vapor pressure is described by the expression \(D \propto P_{As_4 }^{ - m} \), where m≈0.4. The experimental data obtained are interpreted in terms of the concept of the dissociative mechanism of migration of Cr atoms in GaAs.     

Dual-band infrared detectors made on high-quality HgCdTe epilayers grown by molecular beam epitaxy on CdZnTe or CdTe/Ge substrates

In this paper, we present all the successive steps for realizing dual-band infrared detectors operating in the mid-wavelength infrared (MWIR) band. High crystalline quality HgCdTe multilayer stacks have been grown by molecular beam epitaxy (MBE) on CdZnTe and CdTe/Ge substrates. Material characterization in the light of high-resolution x-ray diffraction (HRXRD) results and dislocation density measurements are exposed in detail. These characterizations show some striking differences between structures grown on the two kinds of substrates. Device processing and readout circuit for 128×128 focal-plane array (FPA) fabrication are described. The electro-optical characteristics of the devices show that devices grown on Ge match those grown on CdZnTe substrates in terms of responsivity, noise measurements, and operability.     

50 Jahre Kybernetik in Österreich

The term “cybernetics” is very old, but in the middle of the last century it gained new importance as steering brought new aspects to the area of information technology. This paper deals with the general history of cybernetics and then describes the beginning of this field at Vienna University of Technology. In this context it was an important step, when the book “Cybernetics” by Norbert Wiener first came to Vienna; thus the interest in cybernetic models evolved. Originating from the interest in cybernetic models, three models were recreated (and refined):

1. the model of the conditioned reflex (artificial tortoise),
2. the model of orientation in a maze (mouse), and
3. the model of homeostasis (homeostat).

The third and final part of this paper illustrates the gradual transition to artificial intelligence (AI). Hopes that were tied up with this term are discussed. Apart from that the question of how much has been left of cybernetics and artificial intelligence today is raised. The mouse in the maze is very closely connected to our Emeritus: He built the Viennese version of it as part of his diploma thesis.