Hydroxyalkylation of barbituric acid. III. Product analysis and reaction pathway

Polyetherols containing a thermally stable pyrimidine ring were obtained upon the reaction of hydroxymethyl derivatives of barbituric acid with an excess of ethylene or propylene oxide. The reaction was monitored by ¹H‐NMR and IR spectroscopy for the systems with variable starting molar ratios of reagents. We found that formaldehyde rearranged from N‐hydroxymethyl and oxymethylene bridges into the end of the polyetherol chain during the reaction. Simultaneously, the O‐hydroxymethyl groups underwent blocking by oxirane. The structures of the polyetherols was deduced on the basis of the course of the reaction and the analytical data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Large area synthesis of conical carbon nanotube arrays on graphite and tungsten foil substrates

Conical carbon nanotube (CCNT) arrays were synthesized over a large area of approximately 1 cm² or more on graphite and tungsten foil substrates. Experimental observations reveal that nucleation is caused by catalyst metal cluster in the initial stages, but the tapered morphology occurs due to the difference in the rates of vertical growth by attachment carbon atoms at edges of growing graphene sheets and radial growth with epitaxial nucleation of new graphene layers near bottom at the substrate. The above mechanism is supported through re-growth experiments on straight multi-walled nanotubes and growth kinetics data, which suggest a linear relationship between the growth rate and ratio of diameter to length (d/l) of CCNT.     

Anomale Nutzbereiche beim Schwebungsverfahren

Zusammenfassung Es wird das Zustandekommen der anomalen Bereiche einer Mehrgitterröhre infolge der flächenhaft gekrümmten Charakteristik mit Hilfe einer Taylorschen Entwicklung begründet. Es wird dargelegt, da\ die anomalen Bereiche me\technisch wesentliche Vorteile bieten. Sie dehnen drs Anwendungsgebiet des Schwebungsverfahrens, das bisher im wesentlichen im Bereich hoher Frequenzen lag, nach niedrigen Frequenzen hin aus. Es wird dabei nicht nur nichts an Empfindlichkeit verloren, es kann sogar bei Einstellung sehr niedriger Differenztöne (gegenüber dem normalen Bereich) an Empfindlichkeit gewonnen werden. Die anomalen Bereiche können aufgefa\t werden als Einzelfall einer Erweiterung des Schwebungsverfahrens durch Einbeziehung der Frequenzvervielfachung und der Frequenzteilung. Auch auf den allgemeineren Fall dieser Erweiterung wird eingegangen. Es wird ausführlich die geschichtliche Entwicklung des Problems dargelegt und im Anschlu\ an eine allgemeinere Begründung gezeigt, da\ man mit qualitativ gleichem Erfolg eine der Urfrequenzen, anstatt sie einem Gitter zuzuführen, auch in den Anodenkreis einführen kann.     

A parallel algorithm evaluating the reliability of a system with known minimal cuts (paths)

A system with known minimal cuts is considered. In order to compute its reliability a binary tree is constructed with nodes being assigned numerical values. The value of each non-leaf node is a linear combination of its child nodes' values. The values of leaf nodes can be computed in a very simple way. The value of the root node is the system's reliability. The presented method is a memory saving one. Moreover, it is possible to apply parallel computation to the nodes located on the same level, which may significantly reduce the computing time.     

Effect of processing on the amino acid content of New Zealand spinach (Tetragonia tetragonioides Pall. Kuntze)

The aim of this work was to evaluate the effect of processing on the amino acid content and protein quality of New Zealand spinach (Tetragonia tetragonioides Pall. Kuntze). In this research, fresh and cooked New Zealand spinach as well as two frozen products prepared for consumption, one obtained using the traditional method (blanching–freezing–storage–cooking) and the other a convenience food product obtained using a modified process (cooking–freezing–storage–defrosting and heating in a microwave oven), were analysed. Glutamic acid was the dominant amino acid in fresh New Zealand spinach, and the limiting amino acids were cystine and methionine. Technological and culinary processing caused a significant increase in amino acid content in 100 g of edible portion, with the exception of methionine and cystine in frozen products prepared for eating. Changes in amino acid content expressed in g/16 g of N (which corresponded to 100 g tissue protein) were not significant, with the exception of the lower glutamic acid content in the frozen product obtained using traditional processing method.     

On reliability of a certain elementary safety system

The paper deals with the determination of reliability of an elementary safety system which consists of two identical elements used simultaneously (hot reserve) whereas for correct system operation is enough when one out of it is good. The operation time is so short that is assumed it is of zero length. Knowing the reliability of element, reliability of system is found.