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  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous measurement of free-surface velocity and surfactant concentration via a common laser probe (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1502-1509 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new technique was developed to simultaneously measure the velocity and surfactant surface concentration at an air/water interface via a common laser probe. The surfactant concentration is measured using the nonlinear optical technique of reflected second-harmonic generation (SHG), utilizing an Nd:YAG laser. The transmitted portion of the same laser beam provides illumination for velocity measurements at the interface using the technique of boundary-fitted digital particle image velocimetry (DPIV). The combined SHG and DPIV system was utilized to scan along the free surface of a uniform water flow with a surface barrier trapping hemicyanine, an insoluble monolayer. Measurements were made downstream of the Reynolds ridge, which marks the contamination front and the leading edge of a free-surface boundary layer. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1337069
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetization reversal dynamics in exchange-coupled NiO–Co bilayers (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6585-6587 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We performed a detailed study of the magnetization reversal in polycrystalline exchange-coupled NiO/Co bilayers over 10 decades of field sweep rate dH/dt for different NiO and Co thicknesses. For all sweep rates and thicknesses, the symmetry of the hysteresis loops shows that an identical pinning strength has to be overcome in both directions of the reversal. At low dH/dt the reversal is governed by domain wall displacement while domain nucleation is dominant at higher ones. The dH/dt at which the transition between the two regimes takes place depends on the relative thickness of the NiO and Co layers. It increases (decreases) when the Co (NiO) thickness is increased. Experimentally, it was found that the energy barrier varies linearly with the square root of the area corresponding to the activation (Barkhausen) volume which is consistent with a random walk model of the coupling between antiferromagnetic and ferromagnetic layers. The results can be explained in terms of a thermally activated switching of the NiO magnetization dragged by the Co reversal. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1358822
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  • 3
    Electronic Resource
    Electronic Resource
    Defect generation and breakdown of ultrathin silicon dioxide induced by substrate hot-hole injection (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 2338-2346 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hole-induced bulk and interface defect generation and breakdown in ultrathin silicon dioxide (2.0 and 3.0 nm) are studied using substrate hot-hole injection. The results show that although these substrate hot holes are effective in creating electrically active damage in the dielectrics, these defects are very ineffective in causing breakdown as compared to those defects created by constant voltage tunneling stress. Identical to hole trapping in thicker oxides, substrate hot-hole defect generation was independent of electric field, decreased with decreasing thickness, and increased with decreasing temperature. The defect generation and breakdown of ultrathin oxides by substrate hot-hole stress is significantly different from that observed for constant voltage tunneling stress. The results suggest that the degradation and breakdown of ultrathin silicon dioxide cannot be explained by the trapping of hot holes alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1389528
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  • 4
    Electronic Resource
    Electronic Resource
    Slow β process in simple organic glass formers studied by one and two-dimensional 2H nuclear magnetic resonance. II. Discussion of motional models (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 10883-10891 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Applying random walk simulations we analyze results of one- (1D) and two-dimensional (2D) 2H nuclear magnetic resonance (NMR) experiments carried out to study the slow β process of toluene-d5 below the glass transition temperature Tg. In this way, we reveal amplitude and mechanism of rotational jumps involved in the secondary relaxation of a rigid molecule. It is shown that essentially all toluene molecules take part in the β-process. In the glass, nearly independent of temperature, the attributed reorientation is restricted to small solid angles of typically 4°–5° for the majority of particles. Only 10%–20% of the molecules exhibit amplitudes χ〉10°. Concerning the mechanism of this highly restricted motion we demonstrate that the reorientation takes place step-by-step via several elementary rotational jumps one after the other. Assuming thermally activated jumps within energy landscapes which are, first, attributed to a small section of the unit sphere for each respective molecule and, second, chosen in accordance with the distribution of energy barriers g(Eβ) found in dielectric spectroscopy we succeed in reproducing the results of 1D and 2D 2H NMR experiments on toluene below Tg. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1415495
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  • 5
    Electronic Resource
    Electronic Resource
    Slow β process in simple organic glass formers studied by one- and two-dimensional 2H nuclear magnetic resonance. I (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 5802-5815 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study the Johari–Goldstein β process of organic glass formers by one- (1D) and two-dimensional (2D) 2H nuclear magnetic resonance (NMR). In particular, we compare systems with pronounced secondary relaxation in dielectric spectroscopy, namely toluene-d5 and polybutadiene-d6 (PB), with compounds which do not exhibit a distinct β peak, i.e., glycerol-d5 and polystyrene-d3 (PS). Choosing large interpulse delays in the applied echo pulse sequences we increase the sensitivity on small angle rotational jumps. This way, we are able to probe clearly the β process of toluene and PB in the line shape of 1D 2H NMR spectra and in the orientational correlation functions of 2D 2H NMR in time domain which is not possible when using the conventional techniques. Below the glass transition temperature Tg, the secondary relaxation of both glass formers is caused by a highly restricted reorientation of essentially all molecules. Comparing our results with simulations we estimate that the reorientation of most toluene molecules and PB monomeric units is characterized by an amplitude χ〈10°. This amplitude is approximately unchanged below Tg, but strongly increases above the glass transition. Closer investigating the 1D 2H NMR line shape for large interpulse delays we moreover demonstrate that the reorientation involved in the β process takes place step-by-step via many elementary rotational jumps. On the other hand, for glycerol and PS, hardly any effects are observed in 1D and 2D 2H NMR experiments below Tg when applying comparable experimental parameters. We conclude that reorientations with an amplitude χ〉1° do not occur on a time scale of μs−ms for the majority of molecules in glassy glycerol and PS. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1351159
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  • 6
    Electronic Resource
    Electronic Resource
    Low-temperature scanning probe microscopy of surface and subsurface charges (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2592-2594 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The operation of a cryogenic scanning force microscope is demonstrated with a sensitivity of about 50 fN/Hz at 5 kHz modulation. This microscope is used as an electrometer in noncontact mode in order to map the local electrostatic forces and capacitance of several nanostructures at 4.2 K. Capacitance imaging of nanostructured surfaces with subatto-Farad resolution is demonstrated. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1360780
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  • 7
    Electronic Resource
    Electronic Resource
    Low-Temperature Aging of Zirconia Ferrules for Optical Connectors (2001)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Zirconia ferrules for optical connectors were examined after aging at 85°C and 95% relative humidity. Two degradation mechanisms were the roughening and the deformation of the zirconia ferrule surface. Raman microscopy revealed that this relatively low-temperature degradation of zirconia ferrules is caused by the tetragonal to monoclinic transformation of zirconia, and is accelerated by stress relief during polishing. The surface upheavals associated with low-temperature aging may significantly degrade the performance of optical connectors over time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2001.tb01085.x
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  • 8
    Electronic Resource
    Electronic Resource
    High Pressure Inactivation of Lactobacillus plantarum in a Model Beer System (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 66 (2001), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : The effects of hop extract and ethanol on growth, high pressure inactivation, and survival of Lactobacillus plantarum were determined in model beer. Corresponding to the beer spoiling ability of this strain, levels of hops and ethanol typical for beer did not inhibit growth. Pressure death time curves determined at 300 MPa were described by an empirical model taking into account the sigmoid shape of survivor curves, sublethal injury, and the presence of baroresistant cells. Ethanol (5 and 10%) enhanced pressure effects on L. plantarum whereas hop extract (50 and 100 ppm) was less effective. In contrast, hop extracts killed pressurized cells during subsequent storage in beer but ethanol did not.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2001.tb16101.x
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  • 9
    Electronic Resource
    Electronic Resource
    Ethanol reduces excitability in a subgroup of primary sensory neurons by activation of BKCa channels (2001)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 14 (2001), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Ethanol effects on the central nervous system have been well investigated and described in recent years; modulations, by ethanol, of several ligand-gated and voltage-gated ion channels have been found. In this paper, we describe a shortening of action potential duration (APD) by ethanol in ≈ 40% of small diameter neurons in rat dorsal root ganglia (DRG). In these neurons, designated as group A neurons, we observed an ethanol-induced increase in whole-cell outward-current. As iberiotoxin, a specific blocker of large-conductance calcium-activated K+ channels (BKCa channels), blocks the effects of ethanol, we investigated the interaction between these channels and ethanol in outside-out patches. Open probability of BKCa channels was increased 2–6 × depending on the concentration (40–80 mm≈ 2–4‰ v/v) of ethanol. Functional consequences were a prolongation of the refractory period, which was reversible after addition of iberiotoxin, and reduced firing frequency during ethanol application. In contrast, another type of neuron (group B) showed a prolonged APD during application of ethanol which was irreversible in most cases. In 90% of cases, neurons of group A showed a positive staining for isolectin B4 (I-B4), a marker for nociceptive neurons. We suggest that the activation of BKCa channels induced by clinically relevant concentrations of ethanol, the resulting modulations of APD and refractory period of DRG neurons, might contribute to clinically well-known ethanol-induced analgesia and paresthesia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0953-816x.2001.01754.x
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  • 10
    Electronic Resource
    Electronic Resource
    Dopamine and noradrenaline efflux in the rat prefrontal cortex after classical aversive conditioning to an auditory cue (2001)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 13 (2001), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We used bilateral microdialysis in the medial prefrontal cortex (PFC) of awake, freely moving rats to study aversive conditioning to an auditory cue in the controlled environment of the Skinner box. The presentation of the explicit conditioned stimuli (CS), previously associated with foot shocks, caused increased dopamine (DA) and noradrenaline (NA) efflux. This conditioned response was dependent on the immediate pairing of the two stimuli; in the pseudoconditioned group that received an equal number of both stimuli, but in an unpaired fashion, no conditioned increases in efflux were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0953-816x.2001.01471.x
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