Polarographische Untersuchungen an 1,3-Thiazinthionen

Polarographic Investigations of 1,3-Thiazinthiones 1,3-Thiazine-6-thiones are stepwise reduced in aprotic media to the corresponding radical anions and dianions. In the case of the 2,4-diphenyl derivative ( 1a ) the radical anion is stable in dimethylformamide, whereas the dianion reacts further to yield the bithiazinylidene ( 4 ) among other products. The effect of substituents on the reduction potentials is discussed.     

Weizen w?hrend der Reifung

Zusammenfassung In Fortführung einer früheren Arbeit über chemische Veränderungen der Weizensorte Schirokko während der Reifung [1] wurden die Gliadine und Glutenine mit Hilfe der RP-HPLC näher untersucht. Für die Gliadinfraktion konnte gezeigt werden, daß im Reifungsverlauf die-Gliadine zuerst und die-Gliadine zuletzt auftreten. Zur Entwicklung des reifen, stark differenzierten-Gliadinmusters wird ein relativ langer Zeitraum von ca. vier Wochen nach der Blüte benötigt. Die Chromatogramme der Gluteninfraktion zeigen bei den HMW-Untereinheiten nur qualitative Unterschiede, während bei den LMW-Untereinheiten eine stärkere Differenzierung im Laufe der Reifung zu beobachten ist. Der Anteil der HMW-Untereinheiten am Gesamtglutenin nimmt von ca. 15% auf ca. 30% zu und der der LMW-Untereinheiten von ca. 75% auf ca. 60% ab. Die MMW-Fraktion bleibt mit ca. 10% relativ konstant. Innerhalb der HMW-Fraktion kommt es infolge unterschiedlicher Zunahme der einzelnen Komponenten zu stärkeren Verschiebungen. Während in frühen Reifungsstadien die HMW-Untereinheiten 3 und 10 deutlich stärker vertreten sind als die Untereinheiten 5, 1 und 9 (Bezeichnung entsprechend [2]), dominiert in reifem Schirokko die Untereinheit 5, gefolgt von den Komponenten 3 und 10, während die Untereinheiten 1 und 9 in deutlich geringerer Menge vertreten sind.

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Wheat during maturation: analysis of gliadins and glutenins by RP-HPLC

Summary In continuation of a study of changes in the chemical composition of the wheat variety Schirokko during ripening [Kieffer R et al. (1988) Z Lebensm Unters Forsch 187:339], the gliadins and glutenins were investigated in more detail by RP-HPLC. The chromatograms of the gliadin fraction show very clearly that the-gliadins appear first and the-gliadins last during the ripening process. A relatively long period of about four weeks after flowering is necessary for the development of the ripe, strongly differentiated,-gliadin pattern. The chromatograms of the glutenins exhibit only qualitative changes in the high-molecular-weight subunits during maturation, while the low-molecular-weight subunits show an increasing differentiation, similar to the gliadins. The proportion of high-molecular-weight subunits increases from about 15% to 30% of whole glutenin, while the low-molecular-weight subunits decrease from about 75% to 60%. The medium-molecular-weight subunits remain relatively constant in the range of 10%. Remarkable quantitative shifts between high-molecular-weight glutenins were observed during ripening. While subunits 3 and 10 [nomenclature according to Krause I et al. (1988) Z Lebensm Unters Forsch 186:398] dominate the pattern in early stages, large amounts of subunit 5, followed by decreasing amounts of subunits 3 and 10 and, after longer tires, subunits 1 and 9 are characteristic for ripe Schirokko.

     

Multicomponent Physical Vapor Deposited Films with Homogeneous Molecular Material Distribution Featuring Improved Resist Sensitivity

Each film preparation technique affects the physical properties of the resulting coating and thus defines its applicability in modern device construction. In this context solvent based spin coated and solvent‐free physical vapor deposited molecular glass photoresist films are systematically investigated for their dissolution behavior, sensitivity, and overall lithographic performance. These investigations demonstrate that the solvent‐free physical vapor deposition leads to a marked increase in sensitivity. This could be explained by the individual molecule by molecule deposition step producing a more homogeneous distribution of the multicomponent resist system, especially the photoacid generator. In addition, this assumption is supported by former published simulations focusing on aggregate formation within thin films. This work demonstrates that the lithographic sensitivity of multicomponent resist system is an intrinsic parameter to investigate molecular material distribution and indicates that the applied film preparation technique is crucial for the corresponding performance and applicability.     

Interleaved Ultrawideband Antenna Arrays Based on Optimized Polyfractal Tree Structures

There is considerable interest in interleaving multiple phased array antennas into a single common aperture system. Current phased array antenna technology is limited to narrowband operation, leading to the appearance of grating lobes and strong mutual coupling effects when they are incorporated into the design of a common aperture system. To overcome this obstacle, a new class of arrays, called polyfractal arrays, has been introduced that possess natural wideband properties well suited for large-scale genetic algorithm optimizations. These arrays also possess recursive beamforming properties and an autopolyploidy-based chromosome expansion that can dramatically accelerate the convergence of a genetic algorithm. In addition, a robust Pareto optimization can be applied to reduce the peak sidelobe levels at several frequencies throughout the intended operating band, leading to ultrawideband antenna array designs. Because of their lack of grating lobes, these polyfractal arrays are ideal building blocks for interleaved antenna array systems. This paper develops these concepts, first creating ultrawideband array designs based on polyfractal geometries and then interleaving these designs into a common aperture system. Several examples of interleaved systems are discussed, with one two-array system possessing a peak sidelobe level of nearly -18 dB with no grating lobes over a 20:1 bandwidth with either of the component array mainbeams steered independently up to 60deg from broadside.     

Performance evaluation of adaptive routing algorithms in packet‐switched intersatellite link networks

This paper addresses the performance evaluation of adaptive routing algorithms in non‐geostationary packet‐switched satellite communication systems. The dynamic topology of satellite networks and variable traffic load in satellite coverage areas, due to the motion of satellites in their orbit planes, pose stringent requirements to routing algorithms. We have limited the scope of our interest to routing in the intersatellite link (ISL) segment. In order to analyse the applicability of different routing algorithms used in terrestrial networks, and to evaluate the performance of new algorithms designed for satellite networks, we have built a simulation model of a satellite communication system with intersatellite links. In the paper, we present simulation results considering a network‐uniform source/destination distribution model and a uniform source–destination traffic flow, thus showing the inherent routing characteristics of a selected Celestri‐like LEO satellite constellation. The updates of the routing tables are centrally calculated according to the Dijkstra shortest path algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

Optimization and characterization of amorphous/crystalline silicon heterojunction solar cells

Amorphous hydrogenated silicon/crystalline silicon (a‐Si:H/c‐Si) heterojunction solar cells are investigated and optimized with regard to efficiency and simplicity of processing. Starting with a survey of a‐Si:H/c‐Si heterojunction solar cell results from the literature, we describe the fabrication steps of our a‐Si:H/c‐Si technology and analyze the electronic device properties by quantum efficiency, current–voltage, admittance, and capacitance–voltage measurements. The open‐circuit voltage and the fill factor of the a‐Si:H/c‐Si heterojunction solar cells under investigation are limited by recombination in the neutral zone of the crystalline Si absorber. Recombination at the a‐Si:H/c‐Si‐interface is subsidiary in respect of the limitation of the open‐circuit voltage. Our best n‐type a‐Si:H/p‐type c‐Si solar cell prepared without high‐efficiency features such as back‐surface field or surface texturing has an independently confirmed efficiency of 14.1% and an open‐circuit voltage of 655 mV. Copyright © 2001 John Wiley & Sons, Ltd.     

Gallium gradients in Cu(In,Ga)Se2 thin‐film solar cells

The gallium gradient in Cu(In,Ga)Se₂ (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe₂ and CuGaSe₂ were calculated using density functional theory. The migration barrier for the In_Cu antisite in CuGaSe₂ is significantly lower compared with the Ga_Cu antisite in CuInSe₂, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd.     

Quantification of character-impact odour compounds of roasted beef

Beef was roasted for 7 min in frying pans made of glass (A) or of stainless steel (B). The lower temperature in A yielded a more roasty-sweet flavour and the higher temperature in B a roasty-harsh, more caramellike flavour. Using stable isotope dilution assays the concentration levels of the odour compounds 4-hydroxy-2,5-dimethyl-3(2H)-furanone (I), 2-acetyl-2-thiazoline (II), 2-ethyl-3,5-dimethylpyrazine (III), 2,3-diethyl-5-methylpyrazine (IV), guaiacol (V) and methional (VI) were determined in samples A and B. The data obtained were divided by the corresponding odour thresholds which were evaluated nasally and retronasally. The results indicated that the flavour differences of A and B were preferentially caused by differences in the concentration levels of odorantsI, II, IV, andVI.

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Quantitative Analyse charakteristischer Geruchsstoffe von gebratenem Rindfleisch

Zusammenfassung Rindfleisch wurde 7 min in Pfannen aus Glas (A) und rostfreiem Stahl (B) gebraten. Die niedrigere Temperatur in A führte zu einem stärker röstig-süßen Aroma und die höhere Temperatur in B zu einem röstig-herben, stärker caramelartigen Aroma. Die Konzentrationen der Geruchsstoffe 4-Hydroxy-2,5-dimethyl-3(2H)-furanon (I), 2-Acetyl-2-thiazolin (II), 2-Ethyl-3,5-dimethyl-pyrazin (III), 2,3-Diethyl-5-methylpyrazin (IV), Guajacol (V) und Methional (VI) wurden in den Proben A und B mit Hilfe von Isotopenverdünnungsanalysen bestimmt. Die erhaltenen Werte wurden dividiert durch die entsprechenden nasal und retronasal ermittelten Geruchsschwellen. Die Ergebnisse zeigten, daß die Aromaunterschiede von A und B in erster Linie auf Unterschiede in den Konzentrationen der GeruchsstoffeI,II, IV undVI beruhen.

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Presented in part at the symposium Flavour Precursors, University of Würzburg, Sept. 30th to Oct. 2nd, 1992