The separation of date (Phoenix dactylifera) sterols by liquid chromatography

Summary Isolation of a crystalline plant sterol mixture from the sarcocarp of the date was followed by successive extraction and column chromatography. The composition of the mixture was examined by gas chromatography. An additional gas chromatographic-mass spectroscopic identification of the sterol mixture was carried out after conversion of the sample into its trimethylsilyl derivates. Cholesterol, campesterol, stigmasterol,-sitosterol and isofucosterol were found from the identification of molecular ions, the assignment of fragment ions and the comparison of each spectral feature with that of the authentic compound. The sterol mixture was then examined by high-performance liquid chromatography employing a Zorbax ODS column and an acetonitrile-water-0.1M sodium acetate (90101) solvent system, and the peaks were detected with radiation at 210 nm. Six peaks were found on the chromatogram. The identification of each peak by means of gas chromatography and infrared spectroscopy was followed by the collection of each component. The peaks were an unknown (ghost) peak, isofucosterol, cholesterol, stigmasterol + campesterol, campesterol and-sitosterol, successively. The plant sterol mixture has only been analysed on reverse-phase column packings whereas the hormonal corticosteroids and male or female hormonal steroids have been separated on both normal and reverse-phase column packings.

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Zusammenfassung Nach Isolierung aus dem Fruchtfleisch der Dattel wurde ein Gemisch kristallisierter pflanzlicher Sterine der stufenweisen Extraktion und Säulenchromatographie unterworfen. Dessen Zusammensetzung wurde gaschromatographisch untersucht. Außerdem wurde dieses Steringemisch gaschromatographisch-massenspektrographisch nach Überführung in die entsprechenden Trimethylsilylderivate identifiziert. Cholesterin, Campesterin, Stigmasterin,-Sitosterin und Isofucosterin wurden durch Nachweis der Molekularionen, durch Zuordnung der Fragmentionen und durch Vergleich mit dem spektralen Verhalten der betreffenden authentischen Verbindung festgestellt. Das Steringemisch wurde dann im Wege der Hochleistungs-Flüssigchromatographie untersucht. Hierzu diente eine Zorbax ods-Säule und ein Lösungsmittelgemisch aus Acetonitril—Wasser—0,1M Natriumacetat (90 10 1). Die Peaks wurden durch Lichtstrahlen von 210 nm nachgewiesen. Sechs Peaks wurden gefunden. Nach Identifizierung durch Gaschromatographie und IR-Spektroskopie wurde jede einzelne Verbindung gesammelt. Neben einer unbekannten Zacke entsprachen die Peaks der Reihe nach dem Isofucosterin, dem Cholesterin, Stigmasterin+Campesterin, Campesterin und-Sitosterin. Das Gemisch der pflanzlichen Sterine wurde nur mit phasenverkehrten Säulen analysiert, während Corticosteroidhormone sowie männliche und weibliche Steroidhormone sowohl auf normalen wie auf phasenverkehrten Säulenpackungen getrennt wurden.

     

Chirality control in oligothiophene through chiral wrapping

[structure: see text] Mixing oligothiophenes and polysaccharides, such as amylose and schizophyllan, affords novel inclusion complexes, in which oligothiophene guests adopt twisted conformation in the chiral channel created by left- or right-handed helical wrapping with the polysaccharide host polymers, leading to optical activity.     

Local well-posedness for the Zakharov system on the multidimensional torus

The initial value problem of the Zakharov system on the two dimensional torus with general period is shown to be locally well posed in the Sobolev spaces of optimal regularity, including the energy space. Unlike the one dimensional case studied by Takaoka [18], the optimal regularity does not depend on the period of torus. The proof relies on a standard iteration argument using the Bourgain norms. The same strategy is also applicable to three and higher dimensional cases.     

Low-regularity bilinear estimates for a quadratic nonlinear Schrödinger equation

In this article we establish the bilinear estimates corresponding to the 1D and 2D NLS with a quadratic nonlinearity , which imply the local well-posedness of the Cauchy problem in Hs for s?−1 in the 1D case and for s>−1 in the 2D case. This is a continuation of our study [N. Kishimoto, Local well-posedness for the Cauchy problem of the quadratic Schrödinger equation with nonlinearity , Commun. Pure Appl. Anal. 7 (2008) 1123-1143] on the 1D NLS with nonlinearity . Previous papers by Kenig, Ponce and Vega, and Colliander, Delort, Kenig and Staffilani established local well-posedness for s>−3/4 in 1D and in 2D, respectively, and when the nonlinearity is restricted to cu², papers by Bejenaru and Tao, and Bejenaru and De Silva improved these results to s?−1 in 1D and s>−1 in 2D. The bilinear estimate for 2D also yields an improvement on the growth rate of Sobolev norms of finite energy global-in-time solutions to the 2D cubic NLS.     

A chemically bonded glass-whisker column for gas chromatography

Summary Silica whiskers were grown on the inside of an open-tubular glass capillary column according to a modified version of Schieke's method. The surface of the silica whiskers was modified by reaction with a flowing solution of octadecylsilyl trichloride and hexamethyl-disilazane, then with a mixture of trimethylchlorosilane and hexa-methyldisilazane. The whiskers grown and the surface modifications were examined with a scanning electron microscope and an electron microprobe X-ray analyser. Finally, the chemically bonded glasswhisker columns thus prepared were evaluated with mixtures of hydrocarbons, fatty acid methyl esters andn-alcohols under isothermal or programmed-temperature conditions.

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Eine Säule mit chemisch gebundenen Whiskers für Zwecke der Gaschromatographie

Zusammenfassung Die Innenseite einer kapillaren Glasrohrkolonne wurde nach den Angaben von Schieke mit Quarz-Whiskers versehen. Deren Oberfläche wurde durch Reaktion mit einer fließenden Lösung von Oktadecylsilyltrichlorid und Hexamethyldisilazan, dann mit einer Mischung von Trimethylchlorsilan und Hexamethyldisilazan modifiziert. Die Whiskers und die veränderte Oberfläche wurden mit einem Raster-Elektronenmikroskop und mit einer Röntgenstrahlensonde untersucht. Schließlich wurden diese Säulen mit Kohlenwasserstoff-Gemischen, Fettsäuremethylestern undn-Alkoholen unter isothermen Bedingungen oder bei programmierten Temperaturen getestet.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Nonlinear elasticity of rodlike macromolecules in condensed state

The finite deformation elasticity of gels of stiff rodlike polymer chains is discussed theoretically. Unlike a rubber composed of flexible polymer chains, the elasticity of this system is energetic, and arises from the elastic deformation of the stiff chains which are forced to bend under macroscopic strain. The stress-strain curve of this system is shown to be nonlinear even if the bending of the rods is small, and has a characteristic S-shaped form which is unlike that of a rubber. The effect of orientational order is also discussed.     

Structural change of OH-free fused quartz tube by blowing with hydrogen-oxygen flame

The effect of blowing with a hydrogen-oxygen flame on the structure of an OH-free fused quartz tube was studied by microscopic spectroscopy. The number of OH groups increased within 1000 μm from the outside surface (OSS). The peak decomposition of the IR absorption at around 3600 cm⁻¹ showed that most OH structures were ‘free SiOH’ without the hydrogen bond, and H₂O molecules were also distributed throughout the cross section. The distribution of the fictive temperature, T_F, in the cross section was measured from the peak position of infrared absorption at ≈2200 cm⁻¹. T_F before blowing was ≈1420 K, which is near the strain point, except in the region within 200 μm from the OSS, where T_F steeply decreases approaching the OSS. After blowing, the values of T_F became greater than those before blowing, increasing steeply from the OSS and having a maximum at ≈1000 μm. The steep change near the OSS must be caused by the shorter structural relaxation time due to the SiOH introduced by blowing and H₂O vapor in the flame. The distribution of the intensities of Raman bands at 495 (D₁) and 606 cm⁻¹ (D₂) derived from the planar four- and three-member rings was also measured.     

Infants’ sensitivity to vertical disparity for depth perception

Both horizontal and vertical binocular disparities produce depth perception in adults. In developmental studies, infants aged around 4 to 6 months were shown to perceive depth from horizontal disparity. However, infants’ sensitivity to vertical disparity has not been shown clearly. To examine the sensitivity in infants, this study measured preferential looking behavior of infants aged 20 to 27 weeks. Results showed a significant preference for the stimulus with vertical disparity, providing the first evidence of infants’ sensitivity to vertical disparity. The infants in the same age group did not show preference for stimulus with horizontal disparity when the stimulus were comparable to the stimulus with vertical disparity, while their sensitivity to horizontal disparity was confirmed with the stimuli used in a previous study. Our results would suggest that properties in processing horizontal and vertical disparities are different in infancy, and that the sensitivity to horizontal disparity are still premature in 27 weeks after birth.     

Response of Propionate-Degrading Methanogenic Microbial Communities to Inhibitory Conditions

Applied Biochemistry and Biotechnology - Propionate is a crucial intermediate during methane fermentation. Investigating the effects of different kinds of inhibitors on the propionate-degrading...