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  • 1
    ISSN: 0899-0042
    Keywords: radioenzyme assay ; stereospecific assay ; carnitine acetyl transferase ; L-carnitine family ; L-carnitine ; acetyl-L-carnitine ; propionyl-L-carnitine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of enzymes to assay individual components of the L-carnitine family in pharmaceuticals, foodstuffs, and biological fluids with various forms of detection is reviewed. The most useful enzyme in the assay of compounds of the L-carnitine family is carnitine acetyl transferase (CAT), which catalyses the reversible interconversion of L-carnitine and its short-chain acyl esters. CAT can be used in one or more coupled reactions combined with U.V., or radiolabelled detection, or combined with HPLC, allowing, enantioselective, structurally specific, and, in the case of radiolabelled tracing, highly sensitive assays to be carried out. When compared with chromatographic separation of enantiomers or diastereoisomers, enantioselective enzyme mediated assays may be cheaper, more sensitive, and simpler, but they do not allow the nonpreferred isomer to be assayed. Consequently, they are appropriate for the specific assay of endogenous enantiomeric substrates of the enzyme concerned, in biological samples. The analysis of the other enantiomer in raw materials or in pharmaceuticals must be more properly approached by enantioselective chromatographic methods.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 248-253 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Si—based (Si—C—N and Si—C—Al) nanopowders prepared by laser synthesis process have been studied by XPS and XAES analyses.The changes of the silicon coordination as a function of the carbon fraction in Si—C—N powders have been investigated by a detailed analysis of Si 2p and Si KLL lines and the measurements of the Auger parameter Ek(Si KLL) + Eb(Si 2p). The non-linear dependence of the Auger parameter on the carbon fraction has been interpreted as due to the formation of a carbonitride nanophase, indicating that the ternary powders are not merely a mixture of silicon carbide and silicon nitride.In Si—C—Al powders it has been found that the incorporation of aluminium results in a modified structure of the silicon carbide, as shown by the variation of the different spectral features.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 11 (1993), S. 287-290 
    ISSN: 0263-6484
    Keywords: DNA primase ; nuclear matrix ; nuclear isolation ; heat exposure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have reinvestigated the association of DNA primase activity with the nuclear matrix prepared from exponentially growing HeLa S3 cells. We have found that 25-30 per cent of the nuclear primase activity resists extraction with 2 M NaCl and digestion with Dnase I. Unlike previous investigations, done with the same cell line, the results showed that nuclear matrix-bound DNA primase activity represented less than 10 per cent of the total cell activity. Association of high levels of primase activity with the nuclear matrix was strictly dependent on a 37°C incubation of isolated nuclei prior to subfractionation. Evidence was obtained that the method used for preparing nuclei can have a dramatic effect on the amount of primase activity which is recovered both in the postnuclear supernatant and in isolated nuclei, thus seriously affecting the interpretation of the results about the quantity of DNA primase activity bound to the nuclear matrix.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 12 (1994), S. 37-44 
    ISSN: 0263-6484
    Keywords: Nuclear matrix ; DNA polymerase α ; soluble complexes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Most of the DNA polymerase α activity, bound to the heat-stabilized nuclear matrix prepared from HeLa S3 cells, was released as a matrix extract by sonication. When the extract was centrifuged in a 5-20 per cent linear sucrose gradient no definite peaks of activity could be identified. Most of the activity sedimented to the bottom of the tube under all the conditions tested, whilst the remaining activity was associated with matrix fragments of various and irregular size. No 10 S complexes, containing polymerase activity, were seen after incubation of the extract for 16 h before centrifugation. Other solubilization procedures (i.e. treatment of the matrix with chelating agents, high pH associated with reducing agents, ionic and nonionic detergents) failed to produce release of matrix-bound DNA polymerase α activity. In contrast, we released 10 S complexes, containing polymerase activity, from the matrix prepared from nuclei not exposed to heat. We conclude that a 37°C incubation of isolated nuclei before extraction with 2 M NaCl and DNase I digestion causes DNA polymerase α to bind to the nuclear matrix in a form that cannot subsequently be released as discrete components, at variance with previous results obtained with the matrix prepared from regenerating rat liver.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 12 (1994), S. 129-135 
    ISSN: 0263-6484
    Keywords: Nuclear matrix ; DNA polymerase α ; processivity ; activity ; heat stabilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated whether or not ATP or other nucleoside di- and trisphosphates (including some nonhydrolysable ATP analogues) can stimulate the activity and/or the processivity of DNA polymerase α associated with the nuclear matrix obtained from HeLa S3 cell nuclei that had been stabilized at 37°C prior to subfractionation, as has been reported previously for DNA polymerase α bound to the nuclear matrix prepared from 22-h regenerating rat liver. We have found that HeLa cell matrix-associated DNA polymerase α activity could not be stimulated at all by ATP or other nucleotides, a behaviour which was shared also by DNA polymerase α activity that solubilizes from cells during the isolation of nuclei and that is thought to be a form of the enzyme not actively engaged in DNA replication. Moreover, the processivity of matrix-bound DNA polymerase α activity was low (〈 10 nucleotides). These results were obtained with the matrix prepared with either 2M NaCl or 0·25 M (NH4)2SO4 and led us to consider that a 37° incubation of isolated nuclei renders resistant to high-salt extraction a form of DNA polymerase α which is unlikely to be involved in DNA replication in vivo.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 1434-193X
    Keywords: Ruthenium ; Ring-closing metathesis ; Metathesis ; EPC synthesis ; 1,2-Diaminocyclohex-4-ene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiopure (1R,2R)-1,2-diaminocyclohex-4-ene derivatives have been synthesized by the ruthenium-catalyzed ring-closing metathesis reaction of (4R,5R)-N,N′-bis[(S)-1-phenylethyl]-4,5-diamino-1,7-octadiene dihydrochloride.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 347-350 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical response of 45 single polychlorinated biphenyls to electron impact mass spectrometry was measured by monitoring their positive molecular ion intensity. The results showed little variability in response within the isomer groups with the same number of chlorine atoms, and the average response is proposed as a basis for quantitation of the polychlorinated biphenyl level for the corresponding degree of chlorination. The possibility of distinguishing the level of each polychlorinated biphenyl group by a method as specific and sensitive as gas chromatography combined with mass spectrometry could be very useful, especially in toxicology studies. Preliminary data obtained from application of the technique in studies of marine organisms are presented.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Kinetic Study of Reactions of Substituted Anthracenes with Maleic AnhydrideHerrn Prof. Dr. R. Huisgen in herzlicher Verbundenheit zum 60. Geburtstag gewidmet.Kinetic data for the Diels-Alder addition of 2-, 9- and 9,10-disubstituted anthracenes with maleic anhydride are interpreted in terms of FMO-theory. While the simplest form of FMO-theory does not give satisfactory results, inclusion of eigenvector coefficients at the reacting centers does provide an improvement.
    Notes: Die kinetischen Daten der Diels-Alder-Reaktion von 2-, 9- und 9,10-substituierten Anthracenen mit Maleinsäureanhydrid lassen sich durch die FMO-Theorie in ihrer einfachsten Form nur unbefriedigend beschreiben. Eine Berücksichtigung der Eigenvektorkoeffizienten der reagierenden Zentren bringt eine deutliche Verbesserung der Korrelation.
    Additional Material: 4 Ill.
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  • 9
    Publication Date: 2017-04-04
    Description: Two distinct eruptive events characterize the volcanic activity at Mount Etna during the 2002 to 2005 period.We identified signals of magma ascent preceding these eruptions by geochemical monitoring of both chemical composition and He-isotope ratio of gas emissions from five locations in the peripheral area of the volcano. The geochemical signals are interpreted using the models proposed by Caracausi et al. (2003a, 2003b) and allow identification of episodes of magma ascent and estimation of the pressures of degassing magma. As observed for the 2001 eruption (Caracausi et al., 2003b), magma ascent probably triggered the onset of the 2002–2003 eruption, and minor events of magma ascent were observed between May and December 2003. In contrast to the previous two eruptions, the 2004–2005 eruption was not preceded by significant geochemical signals of volcanic unrest, suggesting that this eruption was mainly triggered by the failure of the upper portion of the volcanic edifice under the magmatic hydrostatic pressure in the conduits. High 3He/4He ratio revealed new volatile-rich magma accumulation. The 2002–2003 eruption was preceded by a much shorter period of new magma accumulation from deep levels of the feeding system. Few minor signals of magma migration were detected at some of the sites during the months preceding the 2004–2005 eruption, suggesting that the degassed 3He-depleted magma resident in the volcanic conduits was not replaced by new volatile-rich magma. This is in agreement with the lack of explosive activity during the 2004–2005 eruption and with petrologic observations that the parent magma probably erupted in 2000 and 2001. New geochemical signals of magma ascent from the deep reservoir have been identified since June 2005, indicating that the volcanic activity of Mount Etna is evolving toward new pre-eruptive conditions.
    Description: Published
    Description: Q06008
    Description: JCR Journal
    Description: reserved
    Keywords: chemical composition ; geochemical monitoring ; He isotope ; magma migration. ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2020-02-24
    Description: We present unprecedented data of real-time measurements of the concentration and isotope composition of CO2 in air and in fumarole-plume gases collected in 2013 during two campaigns at Mount Etna volcano, which were made using a laser-based isotope ratio infrared spectrometer. We performed approximately 360 measurements/h, which allowed calculation of the δ13C values of volcanic CO2. The fumarole gases of Torre del Filosofo (2900mabove sea level) range from 3.24 ± 0.06‰to 3.71 ± 0.09‰, comparable to isotope ratio mass spectrometry (IRMS) measurements of discrete samples collected on the same dates. Plume gases sampled more than 1 km from the craters show a δ13C= 2.2 ± 0.4‰, in agreement with the crater fumarole gases analyzed by IRMS. Measurements performed along ~17km driving track from Catania to Mount Etna show more negative δ13C values when passing through populated centers due to anthropogenic-derived CO2 inputs (e.g., car exhaust). The reported results demonstrate that this technique may represent an important advancement for volcanic and environmental monitoring.
    Description: Published
    Description: 2382–2389
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Real-time data of CO2 content and δ13C in atmospheric/volcanic gases ; This study opens new perspective for the community for volcanic surveillance ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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