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  • 1990-1994  (45)
  • 1965-1969  (28)
  • 1930-1934  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    The structural homogeneity of boron carbide thin films fabricated using plasma-enhanced chemical vapor deposition from B5H9+CH4 (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6919-6924 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Boron carbide thin films of several B/C ratios have been deposited on Si(111) using plasma-enhanced chemical vapor deposition from nido-pentaborane(9) (B5H9) and methane (CH4). X-ray diffraction studies of boron carbide thin films on Si(111) exhibited characteristic microcrystalline diffraction lines. Soft x-ray emission spectroscopy was used to verify that the local electronic structure and composition of each sample corresponded to a homogeneous solid solution boron carbide phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.355066
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  • 2
    Digitale Medien
    Digitale Medien
    A soft-x-ray-emission investigation of cobalt implanted silicon crystals (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7800-7804 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The Si L2,3 emission spectra of silicon crystals implanted with Co at doses of (1–8) × 1017 Co/cm2 have been examined using soft-x-ray-emission (SXE) spectroscopy. At the lowest dose, the spectra are little modified from that of crystalline Si, indicating that only a small fraction of Si is in the form of silicides within the probe depth of SXE spectroscopy. For higher doses and implant profiles with Co extending to the surface, there is clear evidence for ordered CoSi2 combined with richer Co phases, but little evidence for pure Si or for ordered regions of CoSi.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.347508
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  • 3
    Digitale Medien
    Digitale Medien
    Scaling of Ohmic energy confinement with major radius in the Tokamak Fusion Test Reactor (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3996-4001 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ohmic plasma size scans have been carried out in the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)] to measure the influence of the major radius upon energy confinement. The major radius, minor radius, and aspect ratio were varied over wide ranges (R=2.08–3.2 m, a=0.4–0.9 m, and R/a=2.9–8.0) at constant qc. The energy confinement determined from kinetic diagnostics varies strongly with major radius. The data set is less well suited to determine minor radius scaling, but it appears to be distinctly weaker than the major radius scaling. The anomaly in ion thermal conductivity over neoclassical predictions appears to decline with increasing aspect ratio, which is a better ordering parameter for the magnitude of the anomaly than either the minor radius or the major radius. © 1994 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.870869
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  • 4
    Digitale Medien
    Digitale Medien
    Proton spin–lattice relaxation rate in supercooled H2O and H2 17O under high pressure (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4796-4803 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The proton spin–lattice relaxation rate has been investigated as a function of pressure (p≤250 MPa), temperature (180 K≤T≤300 K), and oxygen-17 enrichment (25.7 atom-%, 50.7 atom-%) in metastable water. Intramolecular proton–oxygen 17 dipolar interactions in light water in relation to deuterium electric quadrupole interactions in heavy water carry similar dynamic information and allow the complicated dynamic isotope effect in liquid water to be investigated in the whole metastable range. Under hydrostatic pressure the proton relaxation rate curve R1 (T, p, ωH) has been investigated at five different Larmor frequencies (100 MHz≤ω≤500 MHz). These experiments unequivocally prove the isotropy of reorientational motions of water molecules on a nanosecond time scale and demonstrate the necessity to include fast quasilattice vibrations into a consistent interpretation of the relaxation rates in the dispersion regime.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.458670
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  • 5
    Digitale Medien
    Digitale Medien
    Experiments utilizing ion cyclotron range of frequencies heating on the TFTR tokamak (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2270-2276 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A variety of experiments have been performed on the TFTR tokamak [Wilson et al., Plasma Physics and Controlled Nuclear Fusion Research 1988 (IAEA, Vienna, 1989), Vol. 1, p. 691] utilizing ion cyclotron range of frequencies (ICRF) heating. Of special interest has been the insight into plasma performance gained by utilizing a different heating scheme other than the usual neutral beam injection (NBI). Utilizing ICRF heating allows control over the power deposition profile independent of the plasma fueling profile. In addition, by varying the minority concentration the power split between ion and electron heating can be varied. Confinement has been examined in high recycling gas fueled discharges, low recycling supershot plasmas, and peaked density pellet fueled discharges. Global confinement is found not to be affected by the method or localization of plasma heating, but the calculated local diffusivities vary with the power deposition profile to yield similar global values. In addition, sawtooth stabilization observed with ICRF heating has been investigated and found to occur in qualitative agreement with theory. ICRF sawtooth stabilized discharges exhibit peaked temperature and density profiles and have a safety factor q that appears to fall well below unity on axis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.859646
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  • 6
    Digitale Medien
    Digitale Medien
    High poloidal beta equilibria in the Tokamak Fusion Test Reactor limited by a natural inboard poloidal field null (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2277-2284 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Recent operation of the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Research 1, 51 (1986)] has produced plasma equilibria with values of Λ≡βp eq+li/2 as large as 7, εβp dia≡2μ0ε〈p⊥〉/〈〈Bp〉〉2 as large as 1.6, and Troyon normalized diamagnetic beta [Plasma Phys. Controlled Fusion 26, 209 (1984); Phys. Lett. 110A, 29 (1985)], βNdia≡108〈βt⊥〉aB0/Ip as large as 4.7. When εβp dia(approximately-greater-than)1.25, a separatrix entered the vacuum chamber, producing a naturally diverted discharge that was sustained for many energy confinement times, τE. The largest values of εβp and plasma stored energy were obtained when the plasma current was ramped down prior to neutral beam injection. The measured peak ion and electron temperatures were as large as 24 and 8.5 keV, respectively. Plasma stored energy in excess of 2.5 MJ and τE greater than 130 msec were obtained. Confinement times of greater than 3 times that expected from L-mode predictions have been achieved. The fusion power gain QDD reached a value of 1.3×10−3 in a discharge with Ip=1 MA and εβp dia=0.85. A large, sustained negative loop voltage during the steady-state portion of the discharge indicates that a substantial noninductive component of Ip exists in these plasmas. Transport code analysis indicates that the bootstrap current constitutes up to 65% of Ip. Magnetohydrodynamic (MHD) ballooning stability analysis shows that, while these plasmas are near, or at the βp limit, the pressure gradient in the plasma core is in the first region of stability to high-n modes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.859647
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  • 7
    Digitale Medien
    Digitale Medien
    Investigation of global Alfvén instabilities in the Tokamak Fusion Test Reactor (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2122-2126 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Toroidal Alfvén eigenmodes (TAE) were excited by the energetic neutral beam ions tangentially injected into plasmas at low magnetic field in the Tokamak Fusion Test Reactor (TFTR) [Proceedings of the 11th International Conference on Plasma Physics and Controlled Fusion Research (IAEA, Vienna, 1987), Vol. 1, p. 51]. The injection velocities were comparable to the Alfvén speed. The modes were identified by measurements from Mirnov coils and beam emission spectroscopy (BES). TAE modes appear in bursts whose repetition rate increases with beam power. The neutron emission rate exhibits sawtoothlike behavior and the crashes always coincide with TAE bursts. This indicates ejection of fast ions from the plasma until these modes are stabilized. The dynamics of growth and stabilization were investigated at various plasma currents and magnetic fields. The results indicate that the instability can effectively clamp the number of energetic ions in the plasmas. The observed instability threshold is discussed in light of recent theories. In addition to these TAE modes, intermittent oscillations at three times the fundamental TAE frequency were observed by Mirnov coils, but no corresponding signal was found in BES. It appears that these high-frequency oscillations do not have a direct effect on the plasma neutron source strength.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.860462
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  • 8
    Digitale Medien
    Digitale Medien
    Possible origin of the anomalous magnetization behavior in melt-textured Y1Ba2Cu3O7−δ crystallites (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 406-408 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Magnetization measurements of the hysteresis loop, M(B), of melt-textured Y1Ba2Cu3O7−δ (YBCO) crystallites were performed in external magnetic fields up to 10 T. The M(B) curves exhibit, between the superconducting transition temperature Tc and almost 39 K, a peak at a finite field B* which increases with decreasing temperature. The crystallites possess a high density of dislocations which could have been introduced during the high temperature treatment and/or by stresses created due to differences in the lattice parameter of small inclusions and the YBCO matrix. The large dislocation density together with the high sensitivity of the superconducting order parameter on deviations from the regular crystal structure and the small coherence length are suggested to be responsible for the observed fishtail shape of the magnetization curves.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.110033
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  • 9
    Digitale Medien
    Digitale Medien
    Blatt-Atmung der höheren Bodenpflanzen im tropischen Regenurwald (1968)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 21 (1968), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Respiratory Activity in Leaves from Herbs in the Tropical Rain Forest.—Plants of the undergrowth flora In the tropical lowland rain forest have typical shade-leaves distinguished by low dry matter percent, large leaf area per gram fresh weight and very low respiratory intensity per unit area of leaf blade. When the respiratory intensity measured at 26°C is converted to 20°C, the values lie somewhat lower than those for extreme shade-leaves of the temperate forests of Denmark. The leaf blades of Lomariopsis guineensis have on the whole the lowest respiratory intensity so far measured in leaf blades: 0.06 mg CO2 per 50 cm2 leaf blade (one side only) and hour at 20°C. The semisucculent shade-leaves of Palisota hirsuta constitute an exception with regard to area per gram fresh weight, in which respect they resemble the semi-succulent shade-leaves of the fern Ophioglossum vulgatum in Denmark.Die Bodenflora von höheren Pflanzen in einem tropischen Regenurwald im Tiefland besteht teils aus Kräutern, teils aus kleinen Bäumen, die eventuell zu grossen heranzuwachsen vermögen; dagegen sind absolut keine Straucher vorhanden. Die Blatter von einigen Kräutern im Urwald bei Adiopodoumé, Elfenbeinsküste, (5°, 20’ nördl. Br, 4°, 10’ west. L) wurden untersucht und zwar folgende: Aframomum sceptrum Schum. (Zingiberaceae), Palisota hirsuta Schum. (Commelinaceae) und Lomariopsis guineensis Kuhn (Farn aus der Familie Polypodiaceae).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1399-3054.1968.tb07292.x
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  • 10
    Digitale Medien
    Digitale Medien
    Cerebrale Funktionsstörungen bei persistierender A. primitiva trigemina (1969)
    Springer
    Journal of neurology 195 (1969), S. 283-300 
    Details
    ISSN: 1432-1459
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Nach Mitteilung vier eigener Beobachtungen von Kranken mit Arteria primitiva trigemina (A.pr.tr.) und neurologischen Ausfallserscheinungen wird auf der Basis strömungsmechanischer Befunde und an Hand der klinischen Ausfallserscheinungen die mögliche Pathogenese derselben erörtert. Die volumenstarke persistierende A.pr.tr. wirkt als Shunt-Gefäß zwischen den Durchströmungsgebieten der A. carotis int. und der A. basilaris und begünstigt auf dieser Basis eine relative Carotis- bzw. Mediainsuffizienz. Die klinisch-neurologische Symptomatologie ist dementsprechend grundsätzlich durch eine armbetonte Hemiparese (u. U. kombiniert mit Aphasie) gekennzeichnet, wobei die Intensität der Störungen den ausbildungsfähigen (vornehmlich meningealen) Kollateralkreislaufmöglichkeiten entspricht. Entsprechend der relativen Carotis- bzw. Mediainsuffizienz ist die klinische Symptomatologie bevorzugt durch alle den Gesamtkreislauf instabilisierenden Faktoren zu provozieren. Krankheitsfälle mit persistierender A.pr.tr. weisen relativ häufig gleichzeitig (komplette oder partielle) Verschlüsse der homolateralen A. cerebri media auf. Eine pathogenetisch möglicherweise maßgebliche Bedingung hierfür über lokale Strömungsverlangsamungen im cranialen Abschnitt des Carotissyphon wird diskutiert. Die ebenfalls relative Häufigkeit einer Kombination von persistierender A.pr.tr. mit Subarachnoidalblutungen kann nach den klinischen Befunden pathogenetisch nicht erklärt, sondern nur beschrieben werden.
    Notizen: Summary Following the report of four own cases with an A. primitiva trigemina (A.pr.tr.) and the description of neurological symptoms the possible pathogenesis is discussed on the basis of rheological findings and clinical symptoms. The voluminous A.pr.tr. acts as a shunt between the area supplied by the internal carotid artery and the basilar artery, respectively, thus promoting a relative insufficiency of the carotid or median artery. Accordingly, the clinical-neurological symptoms are consistently marked by a hemiparesis, especially of the arm (sometimes associated with aphasia), the intensity of the disturbances depending on the extent to which a collateral (meningeal, especially) may become effective. Due to the relative insufficiency of the carotid and median artery, respectively, clinical symptoms will become apparent during any kind of circulatory distress. Cases with persistent A.pr.tr. relatively often present concurrent (complete or partial) occlusions of the homolateral A.cerebri media. In discussing pathogenetic possibilities regional decreases of blood flow within the cranial portion of the carotid syphon are considered to play an important role. The also relatively frequent coincidence of the persistent A.pr.tr. with a subarachnoid hemorrhage fails to lend itself to a pathogenetic explanation on clinical grounds and therefore can only be described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00242460
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