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  • 1
    Electronic Resource
    Electronic Resource
    Addendum to "Collective transport of alpha particles due to Alfvén wave instability'' [Phys. Fluids B 5, 3217 (1993)] (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3139-3139 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ya. I. Kolesnichenko and his cowerkers observed that the alpha particle energy losses due to Alfvén wave excitation in an ignited plasma did not exceed 25% of the total alpha particle energy. (AIP)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870507
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  • 2
    Electronic Resource
    Electronic Resource
    Long-Term Activation of Protein Kinase C by Nicotine in Bovine Adrenal Chromaffin Cells (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous results from our laboratory suggest that long-term treatment of primary cultured bovine adrenal medullary (BAM) chromaffin cells with nicotine or phorbol 12-myristate 13-acetate, either of which directly activates protein kinase C (PKC), increases the mRNA levels encoding catecholamine-synthesizing enzymes and proenkephalin. In the present study, we have examined the effects of nicotine on BAM cell PKC activity with special emphasis on long-term effects. Nicotine increased particulate PKC activity in a concentration-dependent manner when measured using in vitro enzyme assay with histone as the substrate. This effect is mediated through nicotinic cholinergic receptors, because 1,1-dimethylphenylpiperazinium, a nicotinic agonist, had a similar effect. In addition, chlorisondamine, a specific nicotine-receptor blocking drug, antagonized the effect of nicotine. Nicotine also increased specific [3H]phorbol 12,13-dibutyrate ([3H]PdBu) binding within 1 min, the effect of which was maximal between 3 and 12 min. This effect was reversed by chlorisondamine similarly after 12 min and after 18 h of nicotine treatment, indicating that continual nicotinic-receptor occupancy is required for persistent PKC activation. Compared to PKC activation, the onset of nicotine-stimulated diacylglycerol production was slow, and it was observed after 12 min of incubation with nicotine. The diacylglycerol levels, specific [3H]PdBu binding, and PKC activity remained significantly elevated for at least 18 h with continuous nicotine incubation. Furthermore, nicotine increased the PKC immunoreactivity of a particulate protein with a molecular mass of 82 kDa in the western blot. These results suggest that nicotinic-receptor activation increases PKC activity and immunoreactivity in BAM cells. The long-term PKC activation may serve several functions, such as activation of mRNA production and a negative feedback regulation of either nicotinic receptors or voltage-dependent Ca2+ channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb10037.x
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  • 3
    Electronic Resource
    Electronic Resource
    Formation of nitrogen-oxygen donors in N-doped Czochralski-silicon crystal (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3347-3350 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The behavior of nitrogen and the formation of nitrogen-oxygen donors in nitrogen-doped Czochralski-silicon crystals (Cz-Si) were studied by the electrical and infrared-absorption measurements in samples annealed in different conditions. Experiments showed that nitrogen-oxygen shallow donors are formed during the nitrogen-doped Cz-Si crystal growth. Nitrogen-oxygen thermal donors are generated in temperature range of 300–550 °C, and the behavior of these thermal donors resembles that of the thermal donors in Cz-Si crystals [P. Wagner, C. Holm, and E. Stirtl, Festkoperprobleme 24, 191 (1984)], but they are monovalent donors with the same levels as those of neutral thermal donors; no new electrically active center is generated in the temperature range of 600–900 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357458
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  • 4
    Electronic Resource
    Electronic Resource
    Harmonic mixing at mm waveband in a high temperature superconducting grain boundary Josephson junction (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2286-2288 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a high Tc superconducting grain boundary Josephson junction, harmonic mixing experiments in the mm waveband were carried out, aiming at as large a harmonic number and as high a signal frequency as possible. The dependencies of intermediate frequency output on dc bias, harmonic number, frequency of local oscillator (LO), and other parameters were carefully studied. Until now, our best result was the mixing between the signal at 95 GHz and the 105th harmonic of LO at about 900 MHz. Preliminary experiments using a high Tc harmonic mixer and phase-locking loop were tried to stabilize the frequency of a mm wave source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356293
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  • 5
    Electronic Resource
    Electronic Resource
    Nitrogen-oxygen complexes in silicon studied by photothermal ionization spectroscopy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2260-2262 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-resolution photothermal ionization spectroscopy has been performed on silicon grown in a nitrogen environment by the Czochralski technique for the first time. Three shallow donors related to the complexes of nitrogen and oxygen impurities D(N-O-3), D(N-O-4), and D(N-O-5) have been observed. Previously unresolved transitions related to the excited states higher than 3p± for D(N-O)s are observed in the spectra as well. The ionization energies of D(N-O)s have been accurately determined as 36.16, 36.41, and 37.37 meV, respectively. In addition, two previously unidentified donor levels found in the absorption spectra of silicon crystal involving nitrogen and oxygen are identified as originating from the splitting of the ground state of phosphorus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106090
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  • 6
    Electronic Resource
    Electronic Resource
    Collective transport of alpha particles due to Alfvén wave instability (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 3217-3226 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently a new point of view has been developed for describing saturation of discrete modes excited by weak sources. The method applies to the evolution of energetic particles in the beam plasma instability as well as to the description of how alpha particles evolve when they destabilize Alfvén waves under reactor conditions. Over a wide range of parameters the system produces pulsations, where there are relatively brief bursts of wave energy separated by longer intervals of quiescence. There are two types of pulsations: benign and explosive. In the benign phase, valid when particle motion is not stochastic, the distribution function is close to that predicted by classical transport theory, and the instability saturates when the wave trapping frequency equals the expected linear growth rate. If the field amplitude in a burst reaches the level where orbit stochasticity occurs, the quasilinear diffusion causes rapid transfer of particle energy to wave energy and rapid flattening of the particle distribution function. The bursting phase is followed by a relatively long quiescent time interval, where the source provides the necessary free energy to regenerate the cycle. The critical issue is whether the instability develops to a high enough level to produce stochastic diffusion. In general, this question can be assessed by using mapping methods to obtain criteria of overlapping of orbit resonances. If overlap occurs, then the modes will saturate at a high level, which will result in significant anomalous transport effects. This picture is consistent with recent observations of energetic beam losses in tokamak experiments due to Alfvén mode excitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860657
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  • 7
    Electronic Resource
    Electronic Resource
    The defects and intergrowth of lead oxides revealed by HRTEM (1992)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 25 (1992), S. 199-204 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: High-resolution transmission electron microscopy (HRTEM) and electron diffraction were used to investigate the microstructure of natural lead oxides found in Panzhihua Mountain, China. The electron diffraction patterns showed crossing of diffraction spots along 〈110〉 directions in litharge and along 〈100〉 directions in massicot and the structural images showed the domain-like texture, probably constructed by arrays of planar defects in the fundamental structures. Based upon the structure of these oxides the possible structural models of planar defects are discussed and the orientation relationship of litharge and massicot is determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889891011871
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  • 8
    Electronic Resource
    Electronic Resource
    A HREM study of nonbasal twinning and superlattices in ilmenite (1990)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 23 (1990), S. 82-87 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The microstructures of natural ilmenite found in Panzhihua district, China, were examined by high-resolution electron microscopy (HREM). The [{\bar 1}2{\bar 1}0] structural images showed clearly the (10{\bar 1}1) nonbasal twinning which seems to be coincident with the [{\bar 1}012] rotation twinning. The superlattices with periodicities of 16.8 and 12.6 Å, respectively, as well as the unit-cell twinning related to the ordering of (10{\bar 1}1) multiple twinnings were observed. The superlattice resulting from the ordering arrangement of (10{\bar 1}1) stacking faults related to the slip systems suggested by Heuer [Philos, Mag. (1966), 13, 379–893] were also detected. Possible genetic aspects are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S002188988901099X
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal configurations of oxygen in silicon (1992)
    Springer
    Applied physics 55 (1992), S. 317-323 
    Details
    ISSN: 1432-0630
    Keywords: 61.70.−r ; 71.55.−i ; 81.40.−z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The central position and the infrared absorption coefficient of the 9 μm band of Si samples were measured with Fourier transform infrared spectroscopy (FTIR) at temperatures from T=77 K to 775 K. The infrared absorption coefficients were corrected by considering background absorption and free carrier absorption calculated from the increased free carrier concentration and from the resistivity determined from Hall effect measurements. We found the central position of the 9 μm band to shift to longer wavelengths with increasing temperature. The concentration [Oi] of interstitial oxygen is almost constant for T〈600 K, but decreased rapidly for T〉600 K. These results verified there are two types of thermal configurations of oxygen in silicon: The bonded Si2O configuration with a binding energy E b≈0.8 to 1.0 eV at T≈77 K to 600 K, and the Si2O configuration coexists with a quasi-free interstitial oxygen (QFIO) state for T〉600 K. The lattice potential barrier E L, which retards QFIO atoms from migrating in the lattice, is estimated to be 1.5 to 1.6 eV. From these configurations the anomalous diffusivity of oxygen in silicon can be explained quite well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324078
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  • 10
    Electronic Resource
    Electronic Resource
    Nitrogen dynamics and growth of seedlings of an N-fixing tree (Gliricidia sepium (Jacq.) Walp.) exposed to elevated atmospheric carbon dioxide (1991)
    Springer
    Oecologia 88 (1991), S. 415-421 
    Details
    ISSN: 1432-1939
    Keywords: Carbon dioxide enrichment ; Symbiotic N-fixation ; Nutrient deficiency ; δ15N ; Gliricidia sepium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seeds of Gliricidia sepium (Jacq.) Walp., a tree native to seasonal tropical forests of Central America, were inoculated with N-fixing Rhizobium bacteria and grown in growth chambers for 71 days to investigate interactive effects of atmospheric CO2 and plant N status on early seedling growth, nodulation, and N accretion. Seedlings were grown with CO2 partial pressures of 350 and 650 μbar (current ambient and a predicted partial pressure of the mid-21st century) and with plus N or minus N nutrient solutions to control soil N status. Of particular interest was seedling response to CO2 when grown without available soil N, a condition in which seedlings initially experienced severe N deficiency because bacterial N-fixation was the sole source of N. Biomass of leaves, stems, and roots increased significantly with CO2 enrichment (by 32%, 15% and 26%, respectively) provided seedlings were supplied with N fertilizer. Leaf biomass of N-deficient seedlings was increased 50% by CO2 enrichment but there was little indication that photosynthate translocation from leaves to roots or that plant N (fixed by Rhizobium) was altered by elevated CO2. In seedlings supplied with soil N, elevated CO2 increased average nodule weight, total nodule weight per plant, and the amount of leaf nitrogen provided by N-fixation (as indicated by leaf δ15N). While CO2 enrichment reduced the N concentration of some plant tissues, whole plant N accretion increased. Results support the contention that increasing atmospheric CO2 partial pressures will enhance productivity and N-fixing activity of N-fixing tree seedlings, but that the magnitude of early seedling response to CO2 will depend greatly on plant and soil nutrient status.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317587
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