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
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 8693-8703 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Expressions are derived for the nuclear quadrupole splittings in the E3 and E4 (para–para) states of (NH3)2 and it is shown that these can be matched with the standard expressions for rigid rotors with two identical quadrupolar nuclei. The matching is exact only when the off-diagonal Coriolis coupling is neglected. However, the selection rules for rotational transitions are just opposite to those for the rigid rotor. Hyperfine splittings are measured for the J=2←1 transitions in the E3 and E4 states with ||K||=1; the quadrupole coupling constants χaa=0.1509(83) MHz and χbb−χcc=2.8365(83) MHz are extracted from these measurements by the use of the above mentioned correspondence with the rigid rotor expressions. The corresponding results are also calculated, with and without the Coriolis coupling, from the six-dimensional vibration–rotation–tunneling (VRT) wave functions of (NH3)2, which were previously obtained by Olthof et al. [E.H.T. Olthof, A. van der Avoird, and P.E.S. Wormer, J. Chem. Phys. 101, 8430 (1994)]. From the comparison of χaa with the measured value it follows that the semiempirical potential and the resulting VRT states of Olthof et al. are very accurate along the interchange (cursive-thetaA,cursive-thetaB) coordinate. From χbb−χcc it follows that this potential is probably too soft in the dihedral angle γ¯=γA−γB, which causes the torsional amplitude to be larger than derived from the experiment. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6408-6419 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of H2S⋅CO2 and two deuterated forms have been observed using a pulsed-beam Fourier-transform microwave spectrometer. For each of the three complexes we assign a-type and c-type transitions which are split into a "weak'' and a "strong'' intensity component. The analysis based on that previously used for the (H2O)2 complex and modified for application to H2S⋅CO2, allowed us to assign internal rotation, inversion tunneling states of the H2S and CO2 units in the complex. The following rotational constants were determined for the ground tunneling state of each species: for H2S⋅CO2, A=11 048.0(26) MHz, B=2147.786(4) MHz, and C=1806.468(4) MHz; for HDS⋅CO2, A=10 769(35) MHz, B=2107.26(24) MHz, and C=1775.83(24) MHz; and for D2S⋅CO2, A=10 356.2(28) MHz, B=2065.376(8) MHz, and C=1746.122(8) MHz. The electric dipole moments were determined for the H2S⋅CO2 and D2S⋅CO2 species, resulting in the values μa=0.410(14) D and μc=0.822(10) D for the H2S⋅CO2 species. The structure of the complex has the CO2 and the S atom of H2S in a T-shaped configuration. The H2S plane is nearly orthogonal to the CO2–S plane with an angle of about 92° and the H2S⋅CO2 center-of-mass separation Rc.m. is 3.498(3) A(ring).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3694-3699 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present hardware and software details of the pulsed molecular beam microwave Fourier transform (MB-MWFT) spectrometer used in the Kiel microwave group. We emphasize an automatic scanning facility which greatly increases the efficiency of MB-MWFT spectroscopy for the measurement of unassigned spectra.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1759-1762 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present the experimental set up of a microwave Fourier-transform spectrometer for the entire K band from 18 to 26.4 GHz. It is hereby shown that this type of spectroscopy is achieved above 18 GHz. Advantages and disadvantages are discussed. The performance is illustrated by the recordings of rotational transitions of various molecules.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Frozen frontal lobe from a patient with cerebrotendinous xanthomatosis and two control specimens were separated by differential centrifugation into subcellular fractions. The fractions were differentiated by their electron microscopic appearance, by their succinate dehydrogenase and acetylcholinesterase activities and by their galactolipid contents. Free cholestanol was present in largest amounts in the myelin fraction and was also found in each subcellular fraction prepared from the cerebrotendinous xanthomatosis brain. Thus, in this condition, cholestanol storage is a property of myelin and probably also of other brain membranes.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Slices of guinea pig cerebral cortex were incubated in bicarbonate- or trisbuffered media. Influx of 45Ca2 +, 54Mn2 +, 133Ba2+ or 90Sr2+ was determined at intervals following addition of the cardiac glycoside, ouabain, to the medium. After incubation for 30 min in the presence of 45Ca2+ and in the absence of ouabain, about 40 per cent of the slice calcium became labelled. Ouabain (01 I″M) markedly increased 45Ca2 + content, as well as the content of unlabelled Ca2 +. Mg2+ and Na+ levels also rose while K+ content dropped at a more rapid rate. Ouabain also brought about increased uptake of 90Sr2+, 133Ba2 + and 54Mn2 +. Lowering the Na+ content of the media prevented the effects of ouabain and brought about an increase in calcium content of brain slices. Addition of 2,4-dinitrophenol (01 mM) or iodoacetate (1 miu) had slight or moderate effects on 45Ca2+ uptake. The data are most compatible with the presence in cerebral tissue of a sodium-calcium exchange process.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 20 (1973), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Procedures used to separate subcellular organelles from fresh brain were applied to brains which had been removed from guinea pigs (1) immediately after death; (2) after the dead animal was maintained at room temperature for 3 h, followed by 16–17 h at 4°C; or (3) after the dead animal was maintained for 19–20 h at room temperature. Subcellular fractionation of the brains in 0.32 M sucrose was followed by discontinuous density gradient centrifugation of the crude mitochondrial fraction. After overnight storage of brains at room temperature, there was a moderate shift in succinate dehydrogenase activity from sub-fraction C (mitochondria) to subfraction B (synaptosomes). There was little change in the distribution of galactolipid among particulate subfractions. There was little change in distributions of monoamine oxidase or acetylcholinesterase activities. Under the less extreme postmortem conditions, there were no shifts in the subcellular distributions of brain enzymes. Ultrastructural changes were much more profound and consisted of losses of identifiable mitochondria and synaptosomes and a progressive increase in very dense bodies. Our results suggest that in spite of the marked morphological changes, meaningful separation of subcellular organelles can be achieved with postmortem tissue.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 16 (1969), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Slices of cerebral cortex were incubated in medium containing 0·75 or 2·8 mM 45CaCl2, in the presence or absence of 0·01–0·1 mm-ouabain. Ouabain induced accumulation of calcium by slices to a maximum of 4 μmoles/g of tissue/hr (0·75 mm-CaCl2 in the medium) and to 8 μmoles/g of tissue/hr (2·8 mm-CaCl2 in the medium). Accumulation of Ca2+ occurred more slowly than loss of K+ from the slices and more closely resembled the pattern of Na+ uptake.Mitochondrial fractions isolated from ouabain-treated slices contained significantly more calcium than controls. Inclusion of EDTA in the homogenization medium resulted in decreased amounts of particulate-bound calcium.The effect of ouabain on accumulation of calcium is discussed with regard to possible relationships to processes of active and passive transport.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 15 (1968), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: An ADP-ATP exchange reaction was studied in NaI-treated microsomes from rat brain. At low concentrations of MgCl2 a nucleotide exchange reaction, elicited in the presence of Na+, had an absolute specificity for ATP. The reaction was stimulated by oligomycin and inhibited by ouabain and EDTA. It is probable that this Na+-stimulated ADP-ATP exchange reaction is a component of the Na-K ATPase system.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 19 (1972), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Movement of 45Ca into and out of cerebral slices in vitro was altered by incubation in Na-free medium or in the presence of ouabain. 45Ca uptake into the ‘non-inulin’ space was more than doubled in slices that were losing Na into Na-deficient media. Replacement of Na in the incubation medium by choline chloride reduced the efflux of 45Ca into Ca-free medium. In the presence of ouabain (10-4M), the rate of efflux was also reduced. NaCN or NaCN plus ethacrynic acid increased the rate of 45Ca efflux. The data are compatible with a sodium-calcium exchange mechanism in cerebral slices.
    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...