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  • 1
    Electronic Resource
    Electronic Resource
    Semiconducting iron disilicide films on Si(111): A high resolution electron energy loss spectroscopy study (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5905-5911 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of β-FeSi2 on Si(111) have been studied by low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS). The observed LEED pattern is consistent with two possible epitaxial orientations. HREELS measurements demonstrate the semiconducting character of the films. The energy gap is determined to Eg(approximately-equal-to)0.92 eV–0.33 meV/K T(K). Additionally a number of optical phonons is found in the range between 200 and 500 cm−1. Theoretical spectra are calculated with optical phonon parameters obtained from infrared data and are compared with the measured spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351898
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  • 2
    Electronic Resource
    Electronic Resource
    An electron–nuclear double resonance study of the lowest triplet state of pyrimidine (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 99-109 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Optically-detected electron–nuclear double resonance was employed to measure the entire hyperfine and quadrupole tensors of the two nitrogen nuclei and the hyperfine tensors of the four hydrogen nuclei in the lowest triplet state T0 of pyrimidine-h4 as a guest in a single crystal of benzene-d6. The electron-spin-density distribution and the molecular geometry in the lowest triplet state have been determined as well as the orientation of the molecule in the benzene crystal. It is found that upon excitation into T0, pyrimidine remains a planar molecule of approximately C2v symmetry; the C–N–C angles, which are 115.5° in the ground state, and the angle between the directions of the nonbonding nitrogen orbitals both become 〉120°. Nearly 60% of the total electron-spin density is located at the two nitrogen atoms, the two nonbonding orbitals each carrying a spin density of 0.21, and the π orbitals a spin density of 0.08. We conclude that the lowest triplet state of pyrimidine is appropriately described in terms of an nπ* excitation; we find no evidence for vibronic coupling of this state with higher lying 3ππ* states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463529
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  • 3
    Electronic Resource
    Electronic Resource
    An electron–nuclear double resonance study of the lowest triplet state of pyrazine (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 110-117 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The hyperfine and quadrupole tensors of the two nitrogen atoms and the hyperfine tensors of the four hydrogen atoms of pyrazine in the lowest triplet state T0 are obtained from optically-detected electron–nuclear double resonance (ENDOR) experiments on pyrazine-h4 in a single crystal of benzene-d6 at 1.2 K. Analysis of these tensors shows that pyrazine is in good approximation a planar molecule of D2h symmetry in the lowest triplet state. The in-plane structure changes significantly upon excitation into T0. An increase of the C–N–C angles is observed and a reduction of the C–N bond lengths. From the hyperfine tensors the distribution of the electron-spin density is derived. The nitrogen nonbonding orbitals together carry 36% of the total spin density and it is shown that the lowest triplet state of pyrazine is appropriately described in terms of a 3nπ* excitation. The results of the optically-detected ENDOR experiments give no indication of vibronic coupling of the lowest 3nπ* state with nearby 3ππ* states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463609
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  • 4
    Electronic Resource
    Electronic Resource
    Co/Ag multilayer film: Role of annealing on the magnetic properties (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1858-1860 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Co(15 A(ring))/Ag(60 A(ring)) multilayers produced by electron beam deposition on a 50 A(ring) chromium buffer layer over a Si(111) wafer have been studied by magnetoresistance, saturation magnetization, coercivity, and anisotropy. Annealing at various temperatures produces striking effects on the observed physical properties, such as an improvement on the value of the magnetoresistance associated to a "back-diffusion'' process in the Co/Ag interfaces. This leads one to believe that interface roughness is indeed most important to understanding the connection between giant magnetoresistance and antiferromagnetic coupling, as well as the behavior of coercivity vs interface anisotropy in these materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108397
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetic Resonance from a Metastable Sulfur-Pair-Related Complex Defect in Silicon (1992)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 83-87 (Jan. 1992), p. 251-256 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/21/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.83-87.251.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    ODMR and Electron Spin Echo Studies on the Non-Radiative Triplet State of the (V-O)° Defect in Silicon (1992)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 83-87 (Jan. 1992), p. 357-362 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/21/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.83-87.357.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of ketanserin on cerebral blood flow and cerebrovascular CO2 reactivity in healthy volunteers (1992)
    Springer
    Acta neurochirurgica 119 (1992), S. 7-11 
    Details
    ISSN: 0942-0940
    Keywords: Carbon dioxide ; cerebral blood flow ; cerebral oxygen metabolism ; cerebral vascular reactivity ; ketanserin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of the anti-hypertensive agent ketanserin on the cerebral blood flow (CBF) and the cerebrovascular CO2 reactivity was examined in 10 healthy volunteers. Ketanserin was administered as an intravenous bolus of 10 mg followed by an infusion of 6mg/h. Before administration CBF was measured by single photon emission computerized tomography (SPECT) of inhaled133 Xenon. Then arterial CO2 tension was subsequently decreased by voluntary hyperventilation and increased by breathing an air/CO2 mixture. The relative changes in CBF induced by the changes in arterial CO2 tension were estimated by the cerebral arterio-venous oxygen content difference method. One hour following the start of ketanserin infusion the SPECT measurement and CO2 manipulations were repeated. The CO2 reactivity (expressed as the slope of the regression line of the linear relation between CBF and PaCO2), was unchanged, i.e. 3.2%/0.1 kPa before ketanserin and 4. 1%/0.1 kPa during ketanserin, respectively. Using regression lines from a semi-logarithmic plot the CO2 reactivity was also unchanged 3.4%/0.1 kPa and 3.5%/0.1 kPa, respectively. Ketanserin did not change CBF. The cerebral oxygen metabolism (CMRO2) was decreased 19% one hour after the start of infusion of ketanserin. In conclusion administration of ketanserin in a clinically relevant dose to healthy volunteers does not change the regional CBF not the cerebrovascular CO2 reactivity, but a decrease in CMRO2 was observed. However further studies are needed to clarify whether ketanserin in fact has a depressing effect on CMRO2 or whether the different results are caused by methodological errors or stocastic variation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01541774
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  • 8
    Electronic Resource
    Electronic Resource
    Mandibular gland secretions of the male beewolvesPhilanthus crabroniformis, P. barbatus, andP. pulcher (Hymenoptera: Sphecidae) (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 27-37 
    Details
    ISSN: 1573-1561
    Keywords: Philanthus crabroniformis ; Philanthus barbatus ; Philanthus pulcher ; Hymenoptera ; Sphecidae ; beewolf ; mandibular glands ; pheromones ; semiochemicals ; mass spectrometry ; infrared spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The composition of the territorial marking pheromones from mandibular glands of males of the beewolvesPhilanthus crabroniformis, P. barbatus, andP. pulcher have been determined. The structures of the components were elucidated by gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectroscopy. The major compound ofP. crabroniformis is isopropyl tetradecanoate, with somewhat lesser amounts of 2-tridecanone, 3-methyl-3-butenyl tetradecanoate, and 92∶8 (Z)∶(E)-11-eicosen-1-ol. The major compounds ofP. barbatus are ethyl tetradecanoate and hexadecanal, which are present in approximately a 60∶40 ratio. These two compounds comprise over 95% of the neutral lipids. Also present in lesser amounts are ethyl dodecanoate, tetradecanal, hexadecan-1-ol, a Δ x -octadecen-1-ol, and octadecan-1-ol. The major compounds ofP. pulcher are ethyl (Z)-7-hexadecenoate and geranylgeraniol acetate, which comprise nearly 90% of the neutral lipid fraction, with smaller amounts of tetradecanal, pentadecanal, and ethyl hexadecanoate; trace amounts of Δ x hexadecenal, hexadecanal, and octadecanal are also present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00997162
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  • 9
    Electronic Resource
    Electronic Resource
    Purification and characterization of seven chloroplast ribosomal proteins: evidence that organelle ribosomal protein genes are functional and that NH2-terminal processing occurs via multiple pathways in chloroplasts (1992)
    Springer
    Plant molecular biology 20 (1992), S. 459-465 
    Details
    ISSN: 1573-5028
    Keywords: rpL20, L32, L33, L36, S12, S16, S19 ; formyl-methionine processing ; RP-HPLC and HPEC ; spinach (Spinacia oleracea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Putative genes for 21 ribosomal proteins (RPs) have been identified in the chloroplast DNA of four plants by nucleotide sequencing and homology comparison but few of the gene products have been characterized. Here we report the purification and N-terminal sequencing of seven proteins from the spinach chloroplast ribosome. The data show them to be the homologues of Escherichia coli RPs L20, L32, L33, L36, S12, S16 and S19, and thus support the view that their genes identified in the chloroplast DNA represent functional genes. The initiating methionine residue was not detected in the mature protein in most cases but it was present in S16, indicating that only the formyl group is removed in this case. This result and the previously reported finding of N-methyl alanine at the N-terminus of chloroplast L2 indicate the existence of multiple N-terminal processing pathways in the chloroplast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040605
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  • 10
    Electronic Resource
    Electronic Resource
    Intra-articular injections and articular cartilage metabolism (1992)
    Springer
    Archives of orthopaedic and trauma surgery 111 (1992), S. 237-242 
    Details
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We studied the effects of repeated intra-articular injections of sterile 140 mM NaCl solution on articular cartilage in adult rabbits. After 20 injections into the knee joints over a period of 4 weeks, chondrocyte glucosaminoglycan synthesis was evenly reduced in all cartilage layers, accompanied by a significant proteoglycan depletion of the matrix which was most marked in the superficial half of the cartilage. These and other changes only partially reversed during a further 4-week period after the injections had been stopped. Our data underline the need for a clear-cut indication for intra-articular injections. The microtrauma caused by injection, in conjunction with the introduction of a carrier solution into the joint, may, at least when repeated at short intervals, lead to measurable damage to the articular cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571486
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