Selective separation of water–alcohol binary mixture through poly(maleimide-co-acrylonitrile) membrane

Separation of various alcohols and water through a membrane was carried out by means of a hydrogen-bonding interaction. A membrane obtained from poly(maleimide-co-acrylonitrile) was effective for a selective separation of water from aqueous alcohol solution by pervaporation technique. Spectroscopic analyses verified that this high selectivity was attributed to the hydrogen-bonding interaction between water and maleimide units in the membrane.     

The structure of neopeptins,inhibitors of fungal cell wall biosynthesis

The structures of neopeptins A (1), B (2), and C (3) were elucidated on the basis of chemical and spectroscopic evidences.     

Identification of the source of the crude drug Tu-zhu-ye using low-temperature plasma ashing

Tu-zhu-ye is a Korean crude drug for use as a diuretic but its plant source has not been identified. The present work has been attempted for identification of the original plant using specimens collected both at Seoul and Taegu, Korea, their mineral microstructures being examined after ashing the specimens by a low-temperature method with high-frequency oxygen plasma. A preliminary survey of the specimens with the naked eye suggested that the Tu-zhu-ye was near to Phyllostachys or its closely related bamboo species. Several specimens, namely, Phyllostachys heterocyclaMitf. var. pubescensOhwi, Phyllostachys nigraMunro var. henonisStapf, Phyllostachys bambusoidesSieb. et Zucc. and Bambusa multiplexRaeuschel were therefore ashed by the low-temperature method and the comparative microscopic studies with the resultant ashed tissues concluded that the “Tu-zhu-ye” from Seoul was perfectly identical with Phyllostachys nigraMunro var. henonisStapf. A further investigation is continued for the specimen from Taegu since it is different from any other specimens provided for the present work.     

Rotons and the gross-pitaevskii equation

With a plausible assumption for ψ(r), a bubble-solution of the GP-equation in the three-dimensional case is obtained. The relation between a roton and a “bubble” is examined. The roton spectrum is derived in order to test the suggested theory of condensate wavefunctions.     

Elasto-plastic bending of an annular plate at large deflection

Summary The elasto-plastic bending of a simply supported annular plate with a free inner edge upon which an uniformly distributed lateral load acts is theoretically investigated, taking into account the influence of the membrane forces. A homogeneous and isotropic elasto-perfectly-plastic material satisfying the Mises' yield condition and the Hencky's stess-strain relation is assumed. The theoretical results are discussed and compared with experimental results obtained with a plate of mild steel; the relation between the real behavior of the actual material and the usual assumptions used in the analysis is emphazised. The theoretical result is also compared with the result of an analysis in which the membrane forces were neglected; in this manner the influence of these forces is shown.

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Übersicht Das elastisch-plastische Biegen einer einfach gelagerten Ringplatte wird theoretisch untersucht, wobei der Einfluß der Membrankräfte berücksichtigt wird. Der innere Rand der Platte ist frei gelagert und trägt eine stetig verteilte Querlast. Es wird ein homogenes, isotropes und ideal elastisch-plastisches Material vorausgesetzt, das der v. Misesschen Fließbedingung und dem Henkyschen Spannungs-Dehnungs-Gesetz genügt. Die Rechenergebnisse werden diskutiert und mit entsprechenden Versuchsergebnissen verglichen, wobei besonderen Wert auf die Beziehung zwischen dem wirklichen Materialverhalten und den üblicherweise in der Theorie verwendeten Annahmen gelegt wird. Die Ergebnisse werden außerdem mit entsprechenden Berechnungsergebnissen verglichen, bei denen die Membrankräfte vernachlässigt wurden, so daß der Einfluß dieser Kräfte deutlich wird.

     

Determination of nitrate in natural waters by flow-injection analysis

Summary Nitrate was determined in natural water samples by flow-injection spectrophotometry. It was reduced to nitrite with copperized cadmium and the nitrite thus produced reacted with p-aminoacetophenone and m-phenylenediamine. The limit of detection was about 1.5 g l^–1 for sample injections of 650 l. The sampling rate was about 40 samples h^–1 and the relative standard deviation was above 1% for 0.1–0.3 mg l^–1 nitratenitrogen. Nitrite present in the sample was determined separately and subtracted.

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Nitratbestimmung in natürlichen Wässern mit Hilfe der Fließinjektions-Analyse

Zusammenfassung Nitrat wird bei dieser Methode mit Hilfe einer Cu/Cd-Reduktionssäule zu Nitrit reduziert, das mit p-Aminoacetophenon und m-Phenylendiamin zur Reaktion gebracht wird. Die gebildete Verbindung wird spektral-photometrisch gemessen. Die Nachweisgrenze beträgt etwa 1,5 g/l bei injizierten Probevolumina von 650 l. Der Probendurchsatz beträgt 40/h. Die relative Standardabweichung liegt über 1% bei 0,1–0,3 mg/l Nitrat-Stickstoff. Vorhandenes Nitrit wird gesondert bestimmt und abgezogen.

     

Sustainable domino Michael reaction catalyzed by a Brønsted base on silica gel: synthesis of bicyclo[2.2.2]octane-2,5-dione derivatives

Domino Michael reactions of oxophorone and its derivatives 4 with Michael partners 3 have been effected to give bicyclo[2.2.2]octane-2,5-dione derivatives 7 by a catalytic amount of a Brønsted base (NMAP-Li) generated from N-methylaminopropylated silica gel (NMAP) and n-BuLi. The NMAP pellets were efficiently reused up to six times in 86% average yield.