Long-term average cost control problems for continuous time Markov processes: A survey

This paper addresses the long-term average cost control of continuous time Markov processes. A survey of problems and methods contained in various works is given for continuous control, optimal stopping, and impulse control.     

Un réactif défini de diazocopulation, le 3-phenyl 5-nitrosamino 1,2,4-thiodiazole ou phenitrazole

3-Phenyl-5-nitrosamino-1:2:4-thiodiazole, or phenitrazole, allows diazo coupling to be carried out in precisely defined conditions. In acid medium it dehydrates to a diazo compound which may be condensed directly with phenols or aromatic amines. The reagent enables the detection of aldehydes of which the corresponding phenylhydrazones lead to formazans. The colorations obtained allow the determination of amounts of the order of hundredths of a milligram.

Zusammenfassung

3-Phenyl-5-nitrosamino-1,2,4-thiodiazol (Phenitrazol) gestattet Diazokupplung unter genau definierten Bedingungen. In saurem Medium dehydriert die Verbindung zu einer Diazoverbindung, die direkt mit Phenolen oder aromatischen Aminen kondensieren kann. Das Reagens ermöglicht die Bestimmung von Aldehyden, deren entsprechende Phenylhydrazone zur Bildung von Formazanen führen. Die erhaltene Färbung gestattet die Bestimmung von Mengen in der Grössenordnung einiger Hundeertstel Milligramm.     

Determination of boron in titanium alloys by means of ion exchange

There is need for a rapid method for the determination of moderate amounts of boron in titanium alloys. In this paper a method is proposed which uses ion exchange. The method is applicable to titanium alloys containing 0.025 to 1 per cent. boron. One or two grams of the sample are dissolved in hydrochloric acid, and the titanium and boron are oxidized with nitric acid. The bulk of the titanium is removed by a cation exchanger. A calcium carbonate separation is made to remove the residual titanium and adjust the acidity. The boron is then titrated with sodium hydroxide, after the addition of mannitol. None of the elements found in commercial titanium alloys interferes with the method.     

Homogeneous supported synthesis using ionic liquid supports: tunable separation properties

[structure: see text] We report a homogeneous supported version of Koser's salt based on a room-temperature ionic liquid (RTIL) support. By altering the nature of the RTIL, a material was developed that was stable, recyclable, and readily separable from the tosyloxylated ketone products just by using variations in solvent polarity. A similar approach should be applicable to a wide range of supported catalysts and reagents.     

Sur un principe de colorimetrie en milieu non aqueux. Son application a l'analyse organique fonctionnelle

In non-aqueous medium it is possible to characterise the hydroxyl, the carbonyl and the aliphatic primary amino groups, by formation of a derivative (an ester, hydrazone or arylamine) containing nitro groups. Without either extraction or elimination of the excess of reagent, a characteristic coloration is developed in dimethylformamide by using an organic base. Determinations are possible on the hundredths of a milligram scale.

Zusammenfassung

In nichtwässrigen Medium ist es möglich Hydroxyl-Carbonyl- und primäre aliphatische Aminogruppen durch Bildung eines Derivates (Ester, Hydrazon oder Arylamin), das eine Nitrogruppe enthält, zu charakterisieren. Ohne extraction oder Entfernung des Reagensüberschusses wird in Dimethylformamid eine charakteristische Färbung erzielt, wenn eine organische Base angewendet wird. Bestimmung im Hundertstel-milligrammbereich sind möglich.     

Transformation des dienes conjugues en sulfones allyliques

The reaction of dienes with arenesulphinic acids or sodium arenesulphinates in acetic acid in the presence of palladium catalysts gives high yields of allylic sulphones containing large proportions of (sometimes exclusively) the more substituted isomer.