ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 4248-4257 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A crossed laser-molecular beam study of the one and two photon dissociation mechanism of bis (cyclopentadienyl) iron (ferrocene, FeCp2) has been performed at 193 and 248 nm. By combining electron bombardment mass spectroscopy with time-of-flight (TOF) measurements, the photodissociation mechanism at 193 nm is shown to have two distinct mechanisms. (1) FeCp2+hν→FeCp*+Cp; (2) FeCp+2hν→FeCp+Cp, FeCp→Fe+Cp. For the first mechanism, which accounts for less than 5% of the photodissociation events, the FeCp* velocity distribution is quantitatively consistent with a statistical dissociation producing FeCp in an excited, ligand field electronic state. The velocity distributions of the Cp and Fe fragments produced by the second mechanism (FeCp is an unstable intermediate) are also in excellent agreement with microcanonical calculations for both Cp elimination steps using the known metal–ligand bond energies of ferrocene. For the second mechanism, dissociation occurs on the lowest potential energy surface for each Cp elimination. Although one photon is energetically sufficient to remove one Cp ligand from ferrocene, RRKM calculations of the lifetime indicate that Cp elimination is extremely slow for dissociation along the ground electronic state potential energy surface. Hence, after internal conversion to the ground electronic state, the large photon absorption cross section (∼4 A(ring)2) for the experimental irradiation conditions allows additional photons to be absorbed until the dissociation rate exceeds the up pumping rate. The large photon energy causes the dissociation rate to increase by many orders of magnitude for each additional photon absorbed. Consequently, there is strong selectivity for the total number of photons absorbed. Both mechanisms, occurring on two different electronic potential energy surfaces, suggest that dissociation induced by excitation of the ligand-to-metal charge transfer states accessed at 193 nm can be quantitatively described as a statistical, unimolecular decomposition. At 248 nm, the measured product velocity distributions are qualitatively consistent with the mechanism deduced from the 193 nm results, but the energy available for translation at this wavelength is too small to extract quantitative producttranslational energy distributions which are required to independently test the applicability of the statistical dissociation model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 17 (1966), S. 435-437 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Aequationes mathematicae 35 (1988), S. 132-139 
    ISSN: 1420-8903
    Keywords: Primary 11K65 ; Secondary 11N37, 11A25, 43A60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Still another proof is given for Parseval's well-known equation $$\sum\limits_{1 \leqslant r〈 \infty } {|a_r |^2 \cdot \varphi (r) = \parallel f\parallel \begin{array}{*{20}c} 2 \\ 2 \\ \end{array} } $$ forB 2-almost-even arithmetical functionsf with Ramanujan coefficients $$a_r = \frac{1}{{\varphi (r)}} \cdot M(f \cdot c_r )$$ . An explicit “best approximation” off by even functions, constructed from characteristic functions of subsets {n; g.c.d.(n, r) =k} ⊂ $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{\mathbb{N}} $$ is used.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mathematische Zeitschrift 92 (1966), S. 314-320 
    ISSN: 1432-1823
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 27 (1987), S. 50-56 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The Clostridium thermocellum cellulase genes celA and celC encoding endoglucanase A and C were subcloned in a temperature-regulated Escherichia coli expression vector containing the leftward promoterpl of bacteriophage lambda. The level of gene expression was controlled by thermal inactivation of the heat-sensitive lambda cI857 repressor. Under optimal conditions the recombinant endoglucanases A and C were expressed to a level of 10–15% of total cellular protein. Endoglucanase A was partially exported into the periplasmic space, whereas endoglucanase C was found sequestered within the cytoplasm. Overexpression of the celA gene resulted in decreased cell viability concomitant with the accumulation of endoglucanase A in the membrane fraction. In contrast, high-level synthesis of the celC gene product was well tolerated by the host cell. Overproduced endoglucanase C accumulated as a soluble enzyme without detectable formation of inactive inclusion bodies.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 29 (1988), S. 25-31 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Endoglucanase C encoded by the celC gene of Clostridium thermocellum has been purified to homogeneity from a recombinant Escherichia coli strain. It was found that this enzyme is highly efficient in degrading glucans with alternating β-1,4- and β-1,3-linkages but lacks activity on unmodified cellulosic substrates. The properties of endoglucanase C were compared to those of Bacillus subtilis β-glucanase, an enzyme used in the brewing industry for β-glucan degradation. Both enzyme cause a rapid decrease of the viscosity of barley β-glucan as a result of internal chain cleavage. Endoglucanase C hydrolyses non-specifically β-1,3- and β-1,4-bonds adjacent to unsubstituted or 4-O′-substituted cellobiose units. Due to its lower pH optimum and increased thermostability endoglucanase C compares favourably with B. subtilis β-glucanase and seems suitable for use in the mashing process of beer brewing.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Mathematik 72 (1968), S. 355-367 
    ISSN: 1436-5081
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 117 (1986), S. 385-392 
    ISSN: 1434-4475
    Keywords: Halogen exchange, in pyrimidines ; Pyrimidines, 5-ethylsulfonyl-methyl- ; Pyrimidines ; 5-ethylthiomethyl-
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In 2,4-dichloro-5-ethylthiomethylpyrimidines3a, b and in (2,4-dichloro-5-pyrimidinylmethyl)ethyl sulfones5a, b, resp., by reaction with ammonia, diethyl-amine, isopropylamine, sodium methanolate and sodium ethylthiolate, resp., the halogen atoms have been substituted by amino, methoxy or ethylthio groups, resp., and thus the compounds4a–4r and5c–5f have been obtained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 1988-08-01
    Print ISSN: 0175-7598
    Electronic ISSN: 1432-0614
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...