Stereospecific synthesis and antibiotic activity of some cephalosporin analogs

The strategy used for the stereospecific synthesis of benzofused octams as cepham analogs was the conversion of a 3,4-dihydrothioisocarbostyril to a thioimidate, cycloaddition reaction to form a fused β-lactam and subsequent removal of the alkylthio group by Raney nickel hydrogenolysis. Using azidoacetyl chloride for forming the β-lactam and following known procedures, an amido side chain was generated. Two of the carba analogs of cephalosporin so produced showed low levels of antibacterial activity against a number of gram positive and gram negative organisms.     

The growth and decay of sonic waves in a radiating gas at high temperature

The propagation of a sonic discontinuity in an optically thick gray gas at temperature 10⁵°K or higher has been studied. The effects of radiation pressure and radiation energy density have been taken into account, while the profiles structured by radiant heat transfer are imbedded in the discontinuities under high temperature conditions of an optically thick medium. When the sonic discontinuity is propagating into a gas at rest, its velocity of propagation is found to be a constant which is the effective speed of sound in a radiating gas. The fundamental differential equations governing the growth of the sonic discontinuity are obtained and solved. It is concluded that if the sonic discontinuity is a compressive wave of order 1, then it terminates into a shock wave after a critical timet _c which has been determined. But on the other hand, when the sonic discontinuity is an expansion wave of order 1, then it will decay and will vanish ultimately. Particular cases of interest have been studied in details.     

Differentiation of phase objects by spatial filtering

A filter function has been theoretically arrived at, which in a coherent optical system produces an irradiance image distribution that is quasi-linear to the first derivative of the phase of a purely phase varying object. The filter function is generated with the aid of a computer-controlled plotter and experimental results of phase differentiation are presented.     

Applications de la photométrie de flamme à l'analyse des éléments différents aux alcalins et alcalino-terreux

Résumé On a étudié les possibilités de l'usage du photomètre de flamme pour la détermination quantitative de quelques éléments fréquents dans diverses alliages ferreuses. Parmi ces éléments on a étudié spécialment le cobalt, le nickel, le chrome et le manganèse. La sensibilité de ces éléments dans les méthodes de photométrie de flamme est petite et leur émissions sont affectées par la grande concentration du fer des échantillons, même dans les aciers avec des teneurs élevées de nickel et de chrome. On doit donc faire une séparation préalable du fer, que nous avons effectuée par extraction avec des solvants organiques, ayant étudié de même les récupérations quantitatives des autres métaux dans les solutions privées de fer. D'autre part on a étudié les interférences mutuelles de ces éléments pour arriver à des conclusions sur les erreurs que peuvent apparaître on cours des mesures. On discute aussi la séparation préalable du nickel et les modes opératoires. Quelques résultats sont donnés sur l'analyse de divers échantillons d'acier et de ferromanganèse. Les différences entre les valeurs photométriques et obtenues par voie chimique sont aussi indiquées.

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Summary A study has been made of the use of the flame photometer for determining quantitatively some of the elements found in various ferrous alloys. Among these elements, special studies have been made of cobalt, nickel, chromium, manganese. The sensitivity by the high concentration of iron in the samples, even in steels containing much nickel and chromium. Consequently, the iron should be removed beforehand. The writers accomplished this by extraction with organic liquids, after they studied the quantitative recovery of other metals in solutions freed of iron. A study has also been made of the mutual interferences of these elements to arrive at conclusions regarding the errors which may appear during the course of the measurements. A discussion is given of the preliminary separation of nickel and the procedures. Analyses of different samples of steel and ferromanganese are reported. The differences between the photometric values and those obtained by chemical methods are also pointed out.

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Zusammenfassung Die Möglichkeit der Verwendung der Flammenphotometrie zur quantitativen Bestimmung einiger Elemente, die sich häufig in Eisenlegierungen finden, wurde untersucht. Besonders Kobalt, Nickel, Chrom und Mangan wurden hierbei in Betracht gezogen. Die Empfindlichkeit der Flammenphotometrie für diese Elemente ist gering. Deren Emission wird durch hohe Eisenkonzentrationen beeinträchtigt, auch wenn der Gehalt an Nickel und Chrom im Stahl beträchtlich ist. Daher muß das Eisen vorher abgetrennt werden. Dies wurde durch Extraktion mit organischen Lösungsmitteln durchgeführt, da festgestellt werden konnte, daß sich die übrigen Elemente in den von Eisen befreiten Lösungen quantitativ auffinden lassen. Weiters wurde die gegenseitige Störung dieser Elemente untersucht, um auf allenfalls dadurch bedingte Fehler aufmerksam zu werden. Die vorhergehende Abtrennung des Nickels und die dazu geeigneten Methoden werden erörtert. Einige Analysenergebnisse von verschiedenen Stählen und Mangan-Eisen-Legierungen werden angeführt. Die sich zwischen photometrischer und chemischer Analyse ergebenden Differenzen werden angegeben.

     

Ion acoustic solitary waves in density and temperature gradients

The propagation of ion-acoustic K-dV solitary waves in weakly inhomogeneous, collisionless plasmas with gradients both in the density and the temperature of the ions has been considered. The electrons are assumed to be hot and isothermal, and the ions to be warm and adiabatic. The reductive perturbation analysis of the fluid equations is then carried out. The zero order quantities existing in the system due to the presence of the inhomogeneities are taken into account consistently and a set of ‘stretched coordinates’ appropriate for the inhomogeneous system is employed. A more general modified K-dV equation has been derived and its soliton solution is obtained explicitly. It is shown that as the soliton propagates along the temperature gradient, its amplitude and the velocity decrease, and the width increases. Further, it is found that when the two gradients are in opposite directions, the amplitude of the soliton remains constant.     

Two new oxindole alkaloids isolated from Hamelia Patens Jacq.

Two new oxindole alkaloids of the heteroyohimbane type have been isolated from $\text{Hamelia Patens}$ Jacq. Their structures correspond to that of isopteropodine with -OH and -OCH₃ groups at C-10.     

Computer techniques for three-dimensional analysis in atomic-absorption flame photometry

Flame methods, specifically in atomic-absorption work, have been augmented and enhanced by computer techniques for data reduction and mathematical analysis. Three-dimensional graphic display of experimental results allows for both a realistic and comprehensive approach to atomic-absorption analysis. The computer procedures and the mathematical techniques are described. Their coordination establishes quick, reliable, easily interpreted and useful results. The various equipment used is also described. The use of the remote scope (basically a cathode-ray tube) for immediate on-line display of three-dimensional data representation is explored. Several typical problems and their resulting solutions are presented in detail. Variations of absorbance are studied as a function of analyte concentration and a second variable: height of selection zone, concentration of interferent components, feed rate, slit width, or pressure of combustion gases. Variations of absorbance values are closely related to variations of percentual sensitivity.     

Korteweg — de Vries solitons with different co-ordinate stretchings

The differences between the soliton solutions of the K-dV equation for a homogeneous, collisionless plasma, consisting of cold ions and isothermal electrons arising due to the two different sets of stretched co-ordinates have been discussed. In particular, the differences between the amplitudes and the widths of the solitons and their variations with the soliton velocity have been indicated. Further, the experimental implications of these differences and also of the two sets of stretched co-ordinates have been discussed.     

Impulsive rotatory motion of a circular disk in a viscous fluid

Zusammenfassung Es wird eine analytische Methode für die Bestimmung der Geschwindigkeit der Strömung und der Winkelgeschwindigkeit einer kreisförmigen Scheibe gegeben, die in einer zähen, inkompressiblen Flüssigkeit einen Drehstoss erhält.

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This research was sponsored by the US. Army under contract no. DA-11-022-ORD-2059 with the University of Wisconsin.