Library

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
    Springer
    Applied physics 60 (1995), S. 49-55 
    ISSN: 1432-0630
    Keywords: 42.65.An ; 36.40.+d ; 31.20.Sy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Using wave functions determined from ground-state local-density calculations, we have calculated the wave-dispersed free response of the optical nonlinear polarizabilityγ (3)(−3ω;ω,ω,ω), for the C60 molecule andχ (3)(−3ω;ω,ω,ω) i.e. Third-Harmonic Generation (THG) for films using a sum-over-states approach. The influence of screening was determined by applying an external static electric field in separate selfconsistent calculations to evaluate induced dipole moments which was used to determine the static linear and nonlinear polarizabilities. The polarizabilities calculated in the static limit were used to determine an effective screening parameter which was, in turn, used together with an RPA approach to calculate screened wave-dispersed, third-order nonlinear optical properties such asγ (3)(−3ω;ω,ω,ω) andχ (3)(−3ω;ω,ω,ω). Comparing evaluated polarizabilities with experimental values we found that the non-resonant free polarizability compares well in absolute magnitude with experimental results. Inclusion of screening results in a polarizability about two orders of magnitude below the experimental values.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 4 (1971), S. 46-51 
    ISSN: 1432-1041
    Keywords: anticholinergics ; gastrointestinal agents ; intestinal absorption ; parasympatholytics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 14C-methylscopolamine (1.5 or 15 mg) and the non-absorbable markers polyethylene glycol or125I-polyvinyl pyrolidon were taken by mouth or infused directly into the duodenum or the upper jejunum of 8 healthy subjects. Comparison of the radioactivity per unit quantity of marker in intestinal aspirates and in the test solution (A/T ratio) showed that about 20 per cent or less of the label was absorbed during its passage through the upper part of the small intestine. Very small amounts of14C-radioactivity were found in the plasma. Over a 7-day period the urinary excretion of label amounted to 7–15 per cent of the dose given. The A/T ratios and urinary excretion of14C-radioactivity showed that there was no consistent relation between the absorption of14C-label and the dose of methylscopolamine administered or the type of non-absorbable marker used. There was no evidence of breakdown of the drug in the upper small intestine. — In a 9th subject, labelled methylscopolamine was instilled into the middle part of the jejunum. The yield of14C-radioactivity in the urine was only 2.6 per cent, which indicates very poor absorption of the drug from the distal jejunum, ileum or colon.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 3 (1971), S. 93-96 
    ISSN: 1432-1041
    Keywords: Anticholinergics ; gastrointestinal agents ; intestinal absorption ; parasympatholytics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The anticholinergic compound Acabel (the benzilic acid ester of N,N-dimethyl-2-hydroxy-methyl-piperidinium-methyl sulphate), tritium labelled in the piperidine molecule, was administered to 6 healthy voltunteers. Its absorption was measured by comparing the radioactivity in gastrointestinal aspirates with that of an unabsorbed marker. The main uptake of Acabel was localized in the upper part of the small intestine, and amounted to 10–20% of the given dose. — Studiesin vitro showed that3H-Acabel can be metabolized in the small intestine. However,in vivo there was no evidence of its decomposition while the test solution was passing through the proximal part of the digestive tract.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 5 (1972), S. 87-92 
    ISSN: 1432-1041
    Keywords: Anticholinergics ; gastrointestinal agents ; intestinal absorption ; parasympatholytics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A radiochemical technique has been employed to study gastrointestinal absorption of anticholinergic drugs in healthy human subjects. The uptake of all the drugs was largely confined to the most proximal part of the small intestine. Absorption of the tertiary amine atropine was almost 100 per cent and was significantly greater than that of the quaternary nitrogen compounds studied. Of the latter, 15–25 per cent of methylatropine, Acabel® and methylscopolamine were absorbed; very little butylscopolamine was taken up. Hydrolysis of propantheline in the upper small intestine prevented determination of the absorption of the intact drug.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 26 (1993), S. 282-284 
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 71.45.−d ; 78.65.−s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss the collective dipolar resonances of theC 60 molecule described by a spherically symmetric shell. The shell is modeled by a step in the radial direction. We present results for π and π+σ plasmons in good quantitative agreement with recent experiments. New features, like a monopole mode of oscillation, are predicted for theC 60 molecule.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 3 (1986), S. 205-209 
    ISSN: 1434-6079
    Keywords: 36.40 ; 31.20G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electronic structures of small cobalt clusters have been calculated within the local spin density approximation using the LCAO method. The calculations were done for simple geometries with the optimized number of interatomic bonds, and both for the bond length of the cobalt dimer and the bulk metal. The Fermi energy is found to be smaller for Co N clusters withN=3, 4, 5 andN〉10 than for the other ones. The variation of the Fermi energy with the cluster size correlates in a striking way with the observed H2 tendency for chemisorption as found for cobalt clusters in a supersonic beam. Furthermore, the magnetic moments are somewhat smaller for these active clusters. In addition the lowest unoccupied levels of majority spin appear close to the highest occupied levels of minority spin which is not the case for the inert clusters.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 13 (1989), S. 153-159 
    ISSN: 1434-6079
    Keywords: 31.20 ; 36.40 ; 78.70.D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this study we present theoretical X-ray absorption near-edge spectra (XANES) evaluated for Fe2, Ni2, and Ni3 using a modified multiple-scattered wave procedure. The calculations were performed for different internuclear distances of the dimers and by varying the geometry from linear to equilateral triangular for Ni3. The calculated absorption spectra for both Fe2 and Ni2 predict a broad resonant structure at the threshold and weak 1s transitions to unoccupied valence orbitals −5→0 eV giving a shoulder at the threshold. The resonance structure at the threshold of Ni3 appeared to be sensitive to the geometry of the clusters.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 19 (1991), S. 435-438 
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electronic spectrum of C60 is calculated using quantum mechanical methods. The first allowed transition in C60 is calculated at an energy of 3.5 eV and with an oscillator strength of 0.09. Several transitions are found at higher energies with comparatively strong oscillator strengths, the strongest one being at 5.78 eV (λ=214 nm). The calculated energy level diagram of C60 is also used to predict wavelengths for transitions in C 60 + and C 60 − . A comparison is made with some recently observed diffuse interstellar bands at 1180 nm and 1320 nm, which have been speculated to originate from C 60 + .
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1434-6079
    Keywords: 31.20.N ; 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Ionization thresholds and electron affinities have been calculated within the Local Density Approximation (LDA) for the neutral, positively and negatively charged clusters of LaC60 and C60. The evaluated energies are found to be in good agreement with available experimental data. More accurate measurements are however necessary to verify the suggested spheroidal cage structure for these molecules.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 26 (1993), S. 279-281 
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 31.20.+j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Molecular cluster calculations within the local density approximation have been performed in a study of the electronic structure of theC 60 molecule — “Buckminsterfullerene” doped with different atoms asK, Ca, Sc andAl-Cl. Doping withK shows how the valence 4s electron is easily transferred to thet 1u LUMO state of the bareC 60 molecule. Use ofCa andSc as dopant element seems to give a somewhat stronger hybridization between the 4s, 3d wavefunctions with the carbon 2p levels of theC 60 molecule. Doping with the 3p elements show the existence ofn- andp-type dopedC 60, where a partly occupied level occurs in the band gap similar to the donor or acceptor levels in traditionally doped semiconductors.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...