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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 213 (1967), S. 1189-1190 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Significant differences have been found between the concentrations of free dopamine excreted in the urine of normal individuals and schizophrenic ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 22 (1974), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 72 (1983), S. 117-130 
    ISSN: 1432-1424
    Keywords: surface charge ; surface concentration ; calcium channels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Calcium ions affect the gating of Ca currents. Surface charge is involved but to what extent is unknown. We have examined this, using isolated nerve cell bodies ofHelix aspersa and the combined microelectrode-suction pipette method for voltage-clamp and internal perfusion. We found that Ba and Sr currents produced by substitution of these ions for extracellular Ca ions are activated at less positive potentials than Ca currents. Mg ions do not permeate the Ca channel and changes in [Mg]0 produce shifts in the activation-potential curves that are comparable to the effects of changes in [Ba]0 or [Sr]0. Inactivation of Ba currents also occurs at less positive potentials. Perfusion intracellularly with EGTA reduced inactivation of Ca currents as a function of potential, but did not shift the inactivation-potential curve. Hence, Ca current-dependent inactivation which is blocked by intracellular EGTA probably does not involve a similar change of intracellular surface potential. The voltage shifts of activation and inactivation produced by extracellular divalent cations used singly or in mixtures can be described by the Gouy-Chapman theory for the diffuse double layer with binding (Gilbert & Ehrenstein, 1969; McLaughlin, Szabo & Eisenman, 1971). From the surface potential values and the Boltzman distribution, we have computed surface concentrations that predict the following experimental observations: 1) saturation of current-concentration relationships when surface potential is changing maximally; 2) the increase in peak current when Ca ions are replaced by Sr or Ba ions; and 3) the greater inhibitory effect of Mg onI Ba thanI Ca. Theory indicates that surface charge cannot be screened completely even at 1m [Mg]0 and thus that Ca channel properties must be evaluated in the light of surface charge effects. For example, after correction for surface charge effects the relative permeabilities of Ca, Ba and Sr ions are equivalent. In the presence of Co ions, however, Ca ions are more permeable than Ba ions suggesting a channel binding site may be involved.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Philadelphia : Wiley-Blackwell
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 3 (1983), S. 381-395 
    ISSN: 1573-6830
    Keywords: Ca current ; voltage clamp ; ATP ; snail neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Ca currents were examined with regard to their recovery from inactivation. The experiments were done on isolated nerve cell bodies ofHelix aspersa using a combined suction pippet, microelectrode method for voltage clamp, and internal perfusion. Ca currents were separated by suppressing K and Na currents. 2. The time course of recovery was determined by applying a test pulse at intervals ranging from 1 msec to 20 sec after prepulses varying from 20 to 3000 msec in duration. Each pair of pulses was preceded by a control pulse to ensure that the Ca currents had recovered before the next test pair was applied. Ba and Ca currents were compared and the effects of intracellular perfusion with EGTA, ATP, and vanadate were examined. 3. Ba currents recovered in two stages and this time course was well fit by a sum of two exponentials with amplitudes and time constants given byA 1 andτ 1 for the fast component andA 2 andτ 2 for the slow component. In Ba the time constants were unchanged when prepulse durations were prolonged from 70 to 700 msec, although the initial amplitudesA 1 andA 2, particularlyA 2, were increased. 4. Comparable influxes of Ca during the prepulse caused much more inactivation, but interestingly the recovery occurred at the same rate. The time course of Ca current recovery was also fit by a sum of two exponentials, the time constants of which were both smaller than the time constants of Ba current recovery. However, the time constants of Ca current recovery were increased markedly when prepulse durations were prolonged. Increasing the extracellular Ca concentration had a similar effect. 5. Increasing the Ba influx had no effect on the recovery time constants, and the Ba results are consistent with reversible inactivation gating of potential-dependent membrane Ca channels. The Ca results show that Ca influx enhances inactivation. Intracellular perfusion with EGTA resulted in less inactivation in the cast of Ca but it had no effect on Ba currents. Intracellular ATP increased the rate of recovery of Ca currents, and intracellular vanadate inhibited recovery. It is concluded that recovery of Ca channels depends upon both Ca influx and membrane potential and is modulated by agents which affect Ca metabolism.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    ISSN: 0084-6589
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 2 (1968), S. 696-698 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 8
    facet.materialart.
    Unknown
    Amsterdam: Elsevier
    Publication Date: 2018-12-05
    Description: Three billion people cook their food on biomass-fueled fires. This practice contributes to the anthropogenic radiative forcing. Fuel-efficient biomass cookstoves have the potential to reduce CO2-equivalent emissions from cooking, however, cookstoves made from modern materials and distributed through energy-intensive supply chains have higher embodied CO2-equivalent than traditional cookstoves. No studies exist examining whether lifetime emissions savings from fuel-efficient biomass cookstoves offset embodied emissions, and if so, by what margin. This paper is a complete life cycle inventory of 'The Berkeley-Darfur Stove,' disseminated in Sudan by the non-profit Potential Energy. We estimate the embodied CO2-equivalent in the cookstove associated with materials, manufacturing, transportation, and end-of-life is 17kg of CO2-equivalent. Assuming a mix of 55% non-renewable biomass and 45% renewable biomass, five years of service, and a conservative 35% reduction in fuel use relative to a three-stone fire, the cookstove will offset 7.5 tonnes of CO2-equivalent. A one-to-one replacement of a three-stone fire with the cookstove will save roughly 440 times more CO2-equivalent than it 'costs' to create and distribute. Over its five-year life, we estimate the total use-phase emissions of the cookstove to be 13.5 tonnes CO2-equivalent, and the use-phase accounts for 99.9% of cookstove life cycle emissions. The dominance of use-phase emissions illuminate two important insights: (1) without a rigorous program to monitor use-phase emissions, an accurate estimate of life cycle emissions from biomass cookstoves is not possible, and (2) improving a cookstove's avoided emissions relies almost exclusively on reducing use-phase emissions even if use-phase reductions come at the cost of substantially increased non-use-phase emissions.
    Keywords: ddc:330
    Language: English
    Type: doc-type:article
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