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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of technetium(V) complexes with N-(thiocarbamoyl)benzamidines. X-ray crystal structure of bis[N-(N,N-diethylthiocarbamoyl)benzamidinato]oxotechnetium(V) chloride, [TcO(et2tcb)2]Cl (1989)
    s.l. : American Chemical Society
    Inorganic chemistry 28 (1989), S. 834-839 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00304a008
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  • 2
    Electronic Resource
    Electronic Resource
    Single potassium channels in membranes of isolated mesophyll barley vacuoles (1987)
    Springer
    The journal of membrane biology 95 (1987), S. 163-169 
    Details
    ISSN: 1432-1424
    Keywords: K channels ; rectification ; open probability ; plant vacuoles ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Voltage-dependent K channels could be identified in on-cell and excised patch-clamp records on membranes of isolated plant cell vacuoles. The current through a membrane patch is dominated by a channel population with a conductance of about 121 pS in symmetrical 250mm KCl solution. The single channel adopts at least two conducting levels the 121-pS state being most frequently observed. The channel shows outward rectification, representing a cation flux into the vacuoles. The rectification appears to be caused by a vanishing open probability and a short channel lifetime at hyperpolarizing voltages. A selectivity ratio of potassium over sodium of about 6 was derived as an estimate. Occasionally, an additional population of K channels with a single-channel conductance of approximately 18 pS is observed. This channel type exhibits outward rectification as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869161
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for an Inhomogeneous Distribution of Thermal Donors in Silicon from Electrical and Optical Measurements (1986)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 10-12 (Jan. 1986), p. 979-984 
    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/2011/0528/01/59/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.10-12.979.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Γ- and X-band contributions to nonresonant tunneling in GaAs/Al0.35Ga0.65As double quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2517-2519 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-resolved photoluminescence in the picosecond regime is performed on an asymmetric GaAs/Al0.35Ga0.65As double quantum well structure with a barrier thickness of 6 nm to obtain the Γ- and X-point barrier contributions to nonresonant tunneling. Application of hydrostatic pressure up to 37 kbar at 5 K reveals that tunneling via virtual X states is at least 800 times less efficient than via virtual Γ states. Above 24.5 kbar an extremely fast scattering of electrons out of the n=1 quantized level of the narrower quantum well is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101994
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  • 5
    Electronic Resource
    Electronic Resource
    POSSIBILITIES OF USING VERTICAL GEOPHONE ARRAYS (CVA) IN REFLECTION SEISMOLOGY (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 33 (1985), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Vertical geophone arrays in boreholes have been used for many years to study seismic velocities by investigating the first arrivals of records. The development of the vertical seismic profiling (VSP) technique shows possibilities of using the reflected events to close the gap between interpretation of conventional seismic data and physical observations made in the well. Reflected events recorded by vertical arrays (as in VSP) generally have higher signal-to-noise ratio, larger bandwidth and can easily be separated from multiples. The new Continuous Vertical Array (CVA) technique combines vertical arrays in several boreholes with a line of source points near the surface. The result is a multi-covered seismic line similar to that of a conventional seismic survey, but it retains the benefits of observations with vertical arrays. The possibilities of the new technique are discussed with the aid of theoretical considerations, model studies, and a first field case using nine boreholes 500 m apart with depths of 400 m.New data acquisition and processing techniques (mainly migration before stack) have been developed. The CVA-seismic method is still in the development stage but promises new possibilities for detailed surveys in difficult areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1985.tb00764.x
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  • 6
    Electronic Resource
    Electronic Resource
    Shallow and deep donors in n-type Ga1−xAlxAsB: Sn grown by metalorganic vapor-phase epitaxy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 4518-4523 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic properties of Sn, a well-known group IV n-type dopant in GaAs, were studied in Ga1−xAlxAs alloys for the whole compositional range. These Sn-doped Ga1−xAlxAs epitaxial layers were grown by metalorganic vapor-phase epitaxy; Hall measurements were carried out for values ranging from x=0 to 1, Hall data for 0〈x〈0.4 were interpreted assuming a shallow donor bound to the Γ band, and a deep donor with an ionization energy of about 100 meV. Photoluminescence spectra of selectivity excited donor acceptor pairs show the existence of a deep donor at 100 meV below the Γ minimum for x〉0.2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340149
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  • 7
    Electronic Resource
    Electronic Resource
    Plasma potentials of 13.56-MHz rf argon glow discharges in a planar system (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 59-66 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The plasma potential of 13.56-MHz low-pressure argon glow discharges has been measured for various modes of applying the rf power in a geometrically asymmetric planar system. The plasma potential is determined from the energy distribution of positive ions incident on the grounded electrode. The voltages on the excitation electrode (target electrode) are carefully measured and the capacitive sheath approximation is used to relate these measured voltages to the measured plasma potential. This approximation is successful in most of the situations encountered in this low-pressure (20 mTorr) relatively low-power density regime. The effects of superimposing dc voltages on the excitation electrode are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335396
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  • 8
    Electronic Resource
    Electronic Resource
    Frequency dependence of ion bombardment of grounded surfaces in rf argon glow discharges in a planar system (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 3350-3355 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The energy distribution of positive ions incident on a grounded surface in a low-pressure argon planar rf glow discharge system has been measured as a function of excitation frequency from 70 kHz to 13.56 MHz for both capacitive and direct coupling of the rf power to the excitation electrode. The results are interpreted by taking into consideration both the transit time for the ion to traverse the sheath relative to the period of the rf excitation voltage, and the resistive or capacitive characteristics of the sheaths. The importance of system geometry and of the dc potential of the excitation electrode (as determined by external circuitry) on the maximum energy of ions incident on grounded surfaces is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335797
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  • 9
    Electronic Resource
    Electronic Resource
    Potassium channels in Eremosphaera viridis (1985)
    Springer
    Planta 166 (1985), S. 490-499 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyta ; Eremosphaera ; Membrane potential and resistance (light-dependent) ; Light and membrane potential ; Potassium channel ; Signal transfer ; Transient (membrane potential)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dependence of the membrane potential of Eremosphaera viridis on different external concentrations of potassium, sodium, calcium, and protons was compared with the diffusion potential measured in the dark and in the presence of NaN3. In contrast to some other algae, the membrane potential in the light as well as in the dark seemed to be predominantly determined by the calculated diffusion potential and less by an electrogenic pump which, however, seemed to be involved at potassium concentrations 〉1 mol·m-3 and at higher pHos (〉pH 6). Furthermore, some characteristics of an action-potential-like response (CAP) triggered by light-off, and independent of the membrane-potential threshold value, were determined. The CAP had a delay period of 5.4 s and needed 4.5 s for polarization to a plateau. On average, the plateau held for 8.8 s and the CAP lasted 37.7 s. The peak amplitudes of CAP (P AP) exactly followed the Nernst potential of potassium. Other cations like sodium, calcium and protons did not appreciably affect the peak amplitudes of CAP. From these and other results it can be assumed that the CAP is caused by a temporary opening of potassium channels in the plasma membrane of Eremosphaera (Köhler et al., 1983, Planta 159, 165–171). The release of a CAP by light-off has been partly explained by the participation of a transient increase of proton concentration in the cytoplasm. It was possible to trigger a CAP by external pH changes and by the addition of sodium acetate, thus supporting the hypothesis that a pH decrease in the cytoplasm may be one element of the signal transfer from the photosynthetic system to the potassium channels in the plasmalemma. Calcium also seemed to have an influence on triggering the CAP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391273
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  • 10
    Electronic Resource
    Electronic Resource
    Potassium channels in Eremosphaera viridis (1986)
    Springer
    Planta 167 (1986), S. 66-75 
    Details
    ISSN: 1432-2048
    Keywords: Action potential and pH transient ; Chlorophyta ; Eremosphaera ; Plasma membrane (I/V-curves) ; Potassium channel ; Signal transfer ; Voltage and current clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To characterize the assumed potassium channels in the plasma membrane of the green alga Eremosphaera viridis (Köhler et al. 1985), current-voltage (I/V)-curves under resting conditions and during an action-potential-like response (CAP) were constructed using voltage- and current-clamp techniques. Under resting conditions the I/V-curves of Eremosphaera showed a distinct upward bending when approaching zero mV, a nearly straight line in the medium part and a downward bending during strong hyperpolarization. Measurements in light and darkness frequently displayed a parallel shift of the I/V-curve in the middle part, indicating a current source which is slowed down by light-off. Using the voltage-clamp technique, N-shaped I/V-curves were sometimes observed. The potassium concentration outside influenced the downward-bending part of the I/V-curve whereas the tetraethylammonium cation, known to block potassium channels, reduced the upward-bending part in particular. A change in external pH, either to pH 7 or pH 3.1 from a standard pH 5.5, caused an increase in conductivity. Chemically induced action potentials were released in Eremosphaera under voltage-clamp conditions by light-off and there was both a current flow and an increase in conductivity during the CAP. Clamping the membrane potential at a value more negative than Nernst potential of potassium revealed an inward current, whereas clamping at a more-positive value revealed an outward current. The experiments demonstrate that there is no threshold potential in releasing a CAP. The I/V-curves performed under current clamp at the peak of CAP verify a previously found increased conductivity with hyper- or depolarization depending on the external potassium concentration. These experiments provide further evidence that in Eremosphaera potassium channels are involved in the CAP caused by a light-off signal. Additional experiments indicate that after light-off a transient acidification of the cytoplasm takes place in correlation with the CAP and the opening of potassium channels. A preliminary “battery model” is discussed to understand the role of potassium channels during a CAP in pH-regulation of the cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446370
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