The improvement of the amorphous environment of the germanate–tellurate glasses in the presence of the gadolinium ions

Glasses in the system xGd₂O₃·(100 − x)[TeO₂·GeO₂] with 0 ≤ x ≤ 50 mol% have been prepared from melt quenching method. In this paper, we investigated changes of the coordination numbers of germanium, tellurium, and gadolinium ions by investigations of FTIR, EPR, and UV–VIS spectroscopy. By analyzing the structural changes resulted from the IR spectra we found that the bending modes of [GeO₄] structural units and the deformed modes of the Te–O–Te linkages produce intercalation of the [GdO _n ] entities in the germanate–tellurate chain network and densification of the glasses by increasing the number of [GeO₆] structural units. EPR spectra of the studied samples reveal that the gadolinium ions play a role of network former. The UV–VIS spectra show broad UV absorption bands located in the 250–350 nm region. Their intensity increase with the increasing of Gd₂O₃ content showing that these stronger transitions can be due to the presence of the O=Ge bonds (n–π* excitations) of [GeO₅] structural units. The [GeO₅] structural units are more stable thermodynamically than their analogues and the [GeO₆] structural units produce the improvement of the amorphous character of these glasses.     

Thermal images generated by a line-scanning technique: statistical properties

The analysis of statistical parameters of computer-generated therfial images by a line-scanning technique indicates an approach to efficient image transmission.     

Robust decentralized control of parallel dc/dc converters

Robust decentralized linear feedback controllers for parallel operating dc/dc converters, using the structured singular value approach, are investigated. Different structures of decentralized controllers were applied and tested. The controllers were designed for structured and unstructured modeluncertainty. The gain directionality compensation, due to a high condition number was considered.Eine robuste und dezentralisierte Regelung für parallele Gleichstromwandler wurde untersucht. Verschiedene Strukturen des Regelungsverfahren wurden angewandt und getestet. Die Regelung wurde für den Fall der strukturierten und unstrukturierten Perturbation entworfen.     

Acid‐formed pectin gel delays major incomplete kiwi fruit allergen Act c 1 proteolysis in in vitro gastrointestinal digestion

BACKGROUND: It is thought that food sensitisers must be able to reach the intestine in order to sensitise patients. Pectin is a gel‐forming plant polysaccharide that can protect allergens from in vivo gastric digestion and in vitro pepsin digestion. The aim of this study was to examine if pectin gel formed in the acidic environment of the stomach can protect labile allergen from in vitro gastrointestinal digestion. RESULTS: Pectin forms a gel in the acidic conditions of gastric fluid up to a concentration of 1.0 ± 0.14 g L^?1. Four allergenic fruits (kiwi, cherry, apple and banana) form gels in the same manner at the dilutions 14.8 ± 0.4; 8.4 ± 0.2, 9.4 ± 0.35 and 29.1 ± 0.2, respectively. The time necessary for dissolution of 50 g L^?1 pectin gel in intestinal fluid was found to be 70 ± 0.2 min. Pectin gel formed in situ was able to protect Act c 1 from pepsin digestion for 1 h and from further intestinal digestion for one additional hour. CONCLUSION: Pectin gel in an acidic environment protects Act c 1 from pepsin digestion and dissolves slowly in the slightly basic environment of the intestine allowing the survival of fruit allergen for additional time and possible interaction with the gut immune system. Copyright © 2008 Society of Chemical Industry     

Multilayer multimode optical fibre

Multilayer multimode fibres are considered by means of the ray theory, and the optimal distribution of refractive index with respect to pulse broadening is found. It is concluded that even with a low number of layers we can reduce pulse broadening significantly. Low sensitivity to the variations of refractive index distribution is predicted.     

Messung und Berechnung des Wärmeübergangs von einem Heizrohr an eine Kohlewirbelschicht in Wasserdampf und Inertgas

Zusammenfassung Zur Durchführung endothermer Reaktionen zwischen Gas und Feststoff in einer Wirbelschicht werden h?ufig Rohrbündel zur W?rmeübertragung eingebaut. Es wird eine wirtschaftliche Bewertung von Bündeln aus runden Rohren nach w?rmetechnischen Gesichtspunkten vorgenommen. Innerhalb des Projektes “Prototypanlage Nukleare Proze?w?rme—PNP” arbeitet die Bergbau-Forschung gemeinsam mit anderen Firmen an einem Kohlevergasungsverfahren, in dem die W?rme aus Hochtemperaturkernreaktore (HTR) genutzt wird. In der vorliegenden Arbeit wird die W?rmeübertragung von einem Heizrohr an, eine gasdurchtr?mte Wirbelschicht untersucht, deren Kenntnis für die Verwirklichung der allothermen Wasserdampfvergasung wichtig ist. Im einzelnen werden theoretische und experimentelle Untersuchungen zur Aufkl?rung des Mechanismus des W?rmeübergangs vom Heizrohr an, die Wirbelschicht beim Vergasungsproze? durchgeführt. Auszug aus der Dissertation vonV. Petrovic, Aachen 1978.     

Dopamine release in the nucleus accumbens by hypothalamic stimulation-escape behavior

It is known that lateral hypothalamic stimulation or self-stimulation can release dopamine in the nucleus accumbens (NAc). The present experiment illustrates that an aversively motivated behavior can also do this. Rats were prepared with microdialysis probes in the NAc and electrodes in the lateral hypothalamus (LH) or medial hypothalamus (MH). Automatic stimulation of the LH increased extracellular dopamine in the NAc 30% as reported earlier. The animals would perform both self-stimulation to turn the current on and stimulation-escape to turn it off, suggesting a combination of reward and aversion. Escape responding increased extracellular dopamine (DA) 100%, even though there was less total stimulation. Automatic stimulation of the MH did the opposite of the LH by decreasing accumbens dopamine (-20%), and the animals would only perform stimulation-escape, indicative of pure aversion. But again, extracellular DA in the NAc increased 100% during escape responding. Thus DA can be released during negative reinforcement when an animal's behavior is reinforced by escape from lateral or medial hypothalamic stimulation. This suggests that DA release was correlated with stimulation-escape behavior, rather than the aversiveness of automatic stimulation.     

Formation of an intermediate C-S-H phase during the hydrothermal synthesis of gyrolite

An intermediate C-S-H phase, similar to the Assarsson's “Phase Z”, with basal spacing of 16Å formed when β-C₂S or γ-C₂S reacted with silicon dioxide (molar ratio CaO/SiO₂ = 0.5–0.28) for 8 hours at 190°C under hydrothermal conditions. This intermediate C-S-H phase transformed to gyrolite upon prolonged hydrothermal treatment.