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  • Articles  (195)
  • Springer  (195)
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  • 1
    ISSN: 1573-904X
    Keywords: gelatin capsules ; moisture content ; near-infrared spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: gelatin ; crosslinking ; formaldehyde ; dissolution ; near-infrared spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To predict the degree of crosslinking from formaldehyde-stressed hard gelatin capsules (HGCs) using near-infrared spectrophotometry (NIR). Methods. HGCs were exposed to a 150 ppb atmosphere of formaldehyde for 2.25,4.60,9.42, 16.0 and 24.0 hours. The capsules were filled with fresh amoxicillin, placed in a 90° conical reflector cone, and scanned in a NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the intact capsules. Dissolution profiles were then obtained for each experimental group. Results. The dissolution of amoxicillin from the capsules at pH 1.2 was found to decrease with increasing time of exposure to the formaldehyde atmosphere. A set of principal components (PCs) was formed by a linear combination of the absorbance values at each wavelength scanned. A good correlation was established (r2 = 0.963) when PC values from the NIR spectra of the HGCs were regressed against percentage of amoxicillin dissolved at 45 minutes, at pH 1.2. Water content of the capsules was found to be the largest determinant in the variation between HGC spectra at each exposure time. Conclusions. NIR spectrophotometry, combined with PCR, was successful at not only predicting dissolution of HGCs exposed to formaldehyde, but also at determining which wavelengths contributed most to spectral variation of these stressed HGCs.
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  • 3
    ISSN: 1573-904X
    Keywords: etintidine ; high-performance liquid chromatography (HPLC) ; solid extraction ; determination of etintidine in plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper describes a new, rapid solid extraction method for the determination of etintidine in plasma. The method employs a semiautomatic sample preparation system. Plasma samples and the internal standard (cimetidine) were applied onto octyl-bonded silica extraction columns. The extraction columns were then subjected to Tris buffer and water wash and were subsequently loaded onto an automatic sample injection system. The contents of the extraction columns were eluted on-line with a mobile phase of acetonitrile:methanol:0.1% ammonium hydroxide (85:10:5, by volume) onto a silica analytical column and detected by UV absorption at 229 nm. The chromatographic condition separates etintidine from some of its metabolites and other endogenous components in plasma. The detection limit for etintidine was 0.02–0.05 µg/ml when 0.2 ml of plasma was used. This method has been used for the determination of plasma etintidine levels in humans and mice after oral administration of etintidine and was found to be suitable for pharmacokinetic/bioavailability studies of etintidine in humans and animals. The method can also be used for the quantitative determination of cimetidine and certain metabolites of etintidine.
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  • 4
    ISSN: 1573-9104
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La technique d'une part et l'abondance des aliments d'autre part ont causé des modifications dans l'alimentation par les céréales, aussi bien en ce qui concerne la quantité que la qualité. Le développement de la fabrication moderne du pain présente les caractéristiques suivants: préférence du froment, des farines très blanches, des procédés accélérés de fermentation et de cuisson dans la fabrication. En conséquence, on obtient des pains plus riches en calories, mais pauvres en subtances nutritives et aromatiques ayant une croûte mince et molle et une mie légère ne nécessitant pas d'efforts de mastication. En vitaminisant et en révalorisant artificiellement le pain, on ne peut remplacer qu'une partie minime des substances enlevées au blé par la moulure. L'utilisation de plus en plus fréquente de procédés chimiques dans l'agriculture et le stockage des récoltes entraîne l'existence de plus en plus importante de résidus non physiologiques dans le blé. Parmi ces produits et procédés ont été mentionnés: un produit destiné à raccourcir la tige du blé, produit qui influence l'azote des plantes; le pourcentage élevé en plomb découvert dans le blé ayant poussé à proximité des autostrades; le pourcentage plus élevé en „Phenantren“ et „3–4-Benzpyren“, trouvé dans les plantes poussant dans les régions industrielles; la production d'aflatoxine causée par la moisissure des produits emmagasinés; les résidus de produits insecticides connus jusqu'à présent; les modifications néfastes constatées dans le blé traité aux rayons gamma en vue d'une conservation plus facile. Les modifications dues à l'influence de la chaleur de cuisson sont à constater particulièrement dans la croûte du pain; elles frappent avant tout certaines substances sensibles à la chaleur ainsi que des processus de condensation suivantMaillard.
    Abstract: Summary Engineering progress and an abundance of foodstuff are the cause of strong quantitative and qualitative changes observed in our bread. The development of modern bread is marked by a preference given to wheat, by a lower degree of grinding up, by a short time of fermentation and baking, which results in bread of increased caloric content, reduced active agents and content of aroma, in bread with a thin, soft crust and a very porous crumb, thus necessitating a lesser mastication. By means of an artificial enrichment of vitamins, minerals, and separated amino-acids, only a very small part of active agents separated by grinding up can be replaced. Increasing application of chemical processes in agriculture and storage ensued an increased presence of non-physiological residues in corn. Among them are mentioned an agent to shorten the length of stalks that interferes with the nitrogen economy of plants; an increased content of lead in fields near highways; an increased content of phenanthren and 3–4 benzpyren in fields near industrial areas; the possible formation of aflatoxin through getting mouldy during storage; residues of pesticides that have become known up to now; as well as hitherto prove harmful alterations due to ray treatment by gamma rays to corn to achieve a better preservation. Changes brought about by the heat during the baking process are particularly clearly shown in the crust of bread which essentially have regard to damaging heat-sensitive contents and proceedings of condensation according toMaillard.
    Notes: Zusammenfassung Technisierung und Überfluß an Nahrungsmitteln sind Ursache von starken quantitativen und qualitativen Veränderungen der Brotnahrung. Die Entwicklung des modernen Brotes ist durch Bevorzugung des Weizens, niedriger Ausmahlung, kurzer Gär- und Backzeiten gekennzeichnet, was zu Broten von erhöhtem Kaloriengehalt, vermindertem Wirkstoff- und Aromagehalt, von Broten mit dünner, weicher Kruste und sehr poröser Krume führt, die geringere Kauarbeit erfordern. Durch künstliche Anreicherung mit Vitaminen, Mineralstoffen und Aminosäuren kann nur ein kleiner Teil der bei der Vermahlung abgetrennten Wirkstoffe ersetzt werden. Steigende Anwendung chemischer Verfahren in der Land- und Lagerwirtschaft hat die vermehrte Anwesenheit unphysiologischer Rückstände im Getreide zur Folge. Unter ihnen werden erwähnt ein Halmverkürzungsmittel, das in den Stickstoffhaushalt der Pflanzen eingreift, der in der Nähe von Autobahnen erhöhte Bleigehalt, der in industrienahen Gebieten erhöhte Gehalt an Phenanthren und 3–4-Benzpyren, die mögliche Bildung von Aflatoxin durch Verschimmelung während des Lagerns, die bisher bekanntgewordenen Rückstände von Schädlingsbekämpfungsmitteln sowie die bisher nachgewiesenen nachteiligen Veränderungen einer Bestrahlung des Getreides mit Gamma-Strahlen zwecks bequemerer Konservierung. Unter dem Einfluß der Backhitze sich vollziehende Veränderungen kommen besonders deutlich in der Kruste des Brotes zum Ausdruck, die sich im wesentlichen auf eine Schädigung hitzeempfindlicher Inhaltsstoffe und Kondensationsvorgänge nachMaillard beziehen.
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  • 5
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The study distinctly shows that structural changes take place in the silicate framework during the swelling process of glasses in aqueous solutions. The presence of a modified Q3 group is evidence for the exchange of protons and sodium ions; condensation reactions also take place. Using various techniques (1H NMR, infrared spectroscopy and thermal analysis) it has been demonstrated that water is present in the hydrated glass not only in the form of H2O molecules and silanol groups, but also in different structures of these two species. A molar H2O:SiOH ratio was found of approximately 1:1 (in agreement with the assumption that H3O+ ions of the solution and sodium ions of the glass are exchanged and ≡ SiOH and H2O are formed from the hydroxonium ions).
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  • 8
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cluster Analysis has been shown to be partially suitable for the classification of glasses. The expansion of the clusters on the Seger's diagram allows an investigation of the influence of the different glass components. Variation of the SiO2 content results in a smaller change of properties than variation of the Na2O/RO relationship. Principal Component Analysis is convenient for showing correlations between the composition of the examined glasses, the glass structure parameters, and the different electrode properties.
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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