Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (95)
  • Chemistry  (91)
  • Node of Ranvier  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of aconitine on the sodium permeability of the node of ranvier (1974)
    Springer
    Pflügers Archiv 349 (1974), S. 133-148 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Sodium Permeability ; Aconitine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of aconitine (10−5–10−6 g/ml) on membrane potentials and membrane currents of myelinated nerve fibres of Xenopus laevis was investigated. The following observations were made: a) Current clamp conditions: Slow depolarization (10–15 mV), decrease of amplitude and maximum rate of rise of action potential, finally inexcitability. With inward current pulses ‘hyperpolarizing responses’ could be elicited at membrane potentials more negative than the resting potential (E r ). Neither spontaneous activity nor repetitive responses to electrical stimuli were observed. No effects of aconitine were found in Na-free solutions or in the presence of tetrodotoxin. b) Voltage clamp conditions: Development of steady inward current at normal resting potential due to formation of a non-inactivating sodium permeability; heavily poisoned nodes therefore exhibit an N-shaped steady-state current voltage relation with negative slope at membrane potentials more negative thanE r . These non-inactivating sodium channels open more slowly than normal sodium channels, and can only be closed by hyperpolarizing the membrane by about 50 mV. The majority of sodium channels have almost normalτ m; theirm ∞ andh ∞-V relations are shifted by 10–15 mV towardsE r . It is concluded that these changes of the sodium permeability account for the changes of electrical activity observed after treatment with aconitine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586624
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Die Wirkung von Skorpiongift auf die Ionenströme des Ranvierschen Schnürrings (1968)
    Springer
    Pflügers Archiv 303 (1968), S. 133-149 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Ranvierscher Schnürring ; Ionenströme ; Skorpiongift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Wirkung von Skorpiongift (10−6 g/ml) auf die Ionenströme einzelner markhaltiger Nervenfasern von Xenopus laevis wurde in voltage-clamp-Experimenten untersucht. 2. Skorpiongift beeinflußt sowohl die Natrium- als auch die Kalium-Permeabilität der Schnürringmembran. 3. Die hauptsächlichen Wirkungen des Skorpiongiftes auf die Natrium-PermeabilitätP Na sind: a) Die maximale Natrium-Permeabilität $$\bar P_{_{{\rm N}a} } $$ wird auf 60% ihres an der unvergifteten Membran gemessenen Wertes reduziert. b) Die Natriuminaktivierung wird stark verlangsamt und verläuft in zwei Phasen. c) Der zeitliche Verlauf vonP Na kann unter der Annahme beschrieben werden, daß die Variableh aus zwei Komponentenx undy besteht, deren Zeitkonstanten τ x und τ y 4 bzw. 200 mal so groß sind wie τ h der unvergifteten Membran. 4. Die Wirkungen des Skorpiongiftes auf die Kalium-PermeabilitätP K sind: a) Die maximale Kalium-PermeabilitätP K' wird auf etwa 35% ihres Normalwertes vermindert. b) Der Anstieg vonP K bei Depolarisation wird verlangsamt; zwei Phasen können unterschieden werden. 5. Die Wirkungen auf die Natrium-Inaktivierung und auf die Kalium-Permeabilität können die unter dem Einfluß von Skorpiongift beobachtete extreme Verlängerung des Aktionspotentials erklären.
    Notes: Summary 1. The action of scorpion venom (10−6 g/ml) on the ionic currents of single myelinated nerve fibres of Xenopus laevis was studied in voltage clamp experiments. 2. Scorpion venom was found to affect the sodium permeability as well as the potassium permeability of the nodal membrane. 3. The main effects of scorpion venom on the sodium permeabilityP Na are: a) The maximum sodium permeability $$\bar P_{_{{\rm N}a} } $$ is reduced to 60% of its value in the unpoisoned membrane. b) The sodium inactivation is markedly slowed and proceeds in two phases. c) The time course ofP Na can be described assuming that the variableh is the sum of two componentsx andy, whose time constants τ x and τ y are 4 and 200 times τh of the unpoisoned membrane. 4. The effects of scorpion venom on the potassium permeabilityP K are: a) The maximum potassium permeabilityP K' is reduced to about 35% of its normal value. b) The increase ofP K' upon depolarisation is slowed down; two phases can be distinguished. 5. The effects on sodium inactivation and potassium permeability may explain the extreme prolongation of the action potential under the influence of scorpion venom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592631
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Die Wirkung von Skorpiongift auf die Ionenströme des Ranvierschen Schnürrings (1968)
    Springer
    Pflügers Archiv 303 (1968), S. 150-161 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Sodium Inactivation ; Scorpion Venom ; Ranvierscher Schnürring ; Natrium-Inaktivierung ; Skorpiongift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Wirkung von Skorpiongift auf die Inaktivierung der Natrium-PermeabilitätP Na wurde in voltage-clamp-Experimenten an einzelnen markhaltigen Nervenfasern von Xenopus laevis untersucht. 2. Beim normalen Ruhepotential warP Na der vergifteten Membran stärker inaktiviert als an der unvergifteten Membran; bei starken Depolarisationen war die Inaktivierung jedoch unvollständig. 3. Der zeitliche Verlauf vonP Na konnte unter verschiedenen experimentellen Bedingungen mit den Hodgkin-Huxley-Gleichungen beschrieben werden, die wie folgt modifiziert wurden: a) die Variableh wurde durch eine schnelle Komponentex und eine langsame Komponentey ersetzt; b) die Komponentex nahm selbst bei Depolarisationen von mehr als 40 mV nicht auf Null ab.
    Notes: Summary 1. The action of scorpion venom on the inactivation of the sodium permeabilityP Na was studied in voltage-clamp experiments on single myelinated nerve fibres of Xenopus laevis. 2. At the normal resting potentialP Na of the poisoned membrane was more inactivated than the control; at large depolarizations inactivation was, however, incomplete. 3. The time course ofP Na under various experimental conditions could be described by theHodgkin-Huxley equations modified as follows: a) the variableh was split into a fast and a slow component (x andy, respectively); b) componentx did not vanish even for depolarizations by more than 40 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592632
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Influence of calcium ions on the ionic currents of nodes of Ranvier treated with scorpion venom (1972)
    Springer
    Pflügers Archiv 333 (1972), S. 51-61 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Calcium Ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Voltage clamp experiments were done on myelinated nerve fibres of Xenopus laevis to study the effect of calcium on the ionic currents of the nodal membrane treated with scorpion venom. Increasing the calcium concentration of the medium from 1.8 to 7.2 mM produced the following changes of the sodium and potassium permeabilities,P Na andP K: a) The incomplete sodium inactivation, which is typical for nodes of Ranvier treated with scorpion venom, is abolished. The curves relatingm ∞ and τ m to membrane potential are shifted by 8–10 mV towards larger depolarizations.P Na and the time constants of the fast and slow components of the sodium inactivation remain practically unchanged. b) The maximum potassium permeability,P K, which is reduced by scorpion venom to 45% of the value observed in the normal node, increases to 68% by addition of calcium ions; τ n is unchanged. These effects of calcium ions on the ionic permeabilities explain the shortening of the extremely prolonged action potential and the inhibition of spontaneous activity observed in nodes of Ranvier poisoned with scorpion venom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586041
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Gefüge und Korrosionsverhalten eines stickstofflegierten rostfreien Stahls (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 329-335 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Microstructure and Corrosion Behaviour of a Nitrogen Alloyed Stainless SteelThe corrosion behaviour of a nitrogen alloyed stainless steel is investigated using potentiodynamic anodic polarization in physiological NaCl solution. The microstructure of forged samples is determined by microscopy and hardness measurements. The steel shows a globular austenitic structure. In the zone of large forging deformation the grains are elongated. Precipitates are observed in which chromium and molybdenium are enriched. The breakdown potentials range from 200 to 1170 mV vs. SCE, most of the values exceed 500 mV. The breakdown potentials decrease with increasing aspect ratio of the grains and increasing hardness. The precipitates are initial sites for pitting and crater shaped metal dissolution.
    Notes: Das Korrosionsverhalten eines stickstofflegierten rostfreien Stahles wird durch potentiodynamische anodische Polarisation in physiologischer NaCl-Lösung untersucht. Der Gefügezustand geschmiedeter Proben wird mikroskopisch und durch Härtemessungen ermittelt. Der Stahl weist ein globulares austenitisches Gefüge auf, in der Zone starker Schmiedeverformung sind die Körner gestreckt. Es liegen Ausscheidungen vor, in denen Chrom und Molybdän angereichert sind. Der Stahl zeigt Durchbruchspotentiale zwischen 200 und 1170 mV vs. SCE, die meisten Werte liegen über 500 mV. Die Durchbruchspotentiale fallen mit zunehmendem Streckungsgrad der Körner und zunehmender Härte ab. Die Ausscheidungen sind Initialpunkte für loch- und kraterförmigen Materialabtrag.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19980290704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Modifikation von Titan durch Ionenimplantation-Ein Überblick (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 88-97 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Modification of Titanium by Ion Implantation-A ReviewThis paper reviews investigations concerning the effect of ion implantation on the properties of titanium alloys. The correlations between the process parameters and the phase formation in implanted layers, the wear and strength properties as well as the corrosion and oxidation behaviour are described. The application for joint prostheses is mentioned.
    Notes: Es wird ein Überblick über den Einfluß der Ionenimplantation auf die Eigenschaften von Titanlegierungen gegeben. Die Beziehungen zwischen den Prozeßparametern und der Phasenbildung in ionenimplantierten Schichten, den Verschleiß- und Festigkeitseigenschaften sowie dem Korrosions- und Oxidationsverhalten werden dargestellt. Die Anwendung für Gelenkprothesen wird kurz besprochen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970280210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Neue Sol-Gel-Beschichtungen als Korrosions-und Verschleißschutz für NE-Metalle (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 23-29 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: New Sol-Gel Based Coatings as Corrosion- and Wear-Protection On Non-Ferrous MetalsA new composite coating material has been developed for the protection of non-ferrous alloys (e.g. aluminum, magnesium, zinc and brass). The coating materials were prepared by the solgel process from epoxyalkoxysilanes and aromatic diols to act as crosslinking agents. As solvent, alcohols and glycol ethers have been used.The viscosity of the system (7-55 mPas) was established in a way to be used in spray, dip or flow coating processes. The transparent coatings were cured at T = 100-220°C. In corrosion tests, 3000 hours salt-spray climate and 240 hours CASS-test = Copper chloride and Acetic acid added Salt Spray, no infiltration of the metal-coating interface and no „filiform-corrosion“ on A199.5, AlMg3 and AlMgSil was observed. Brass samples showed less than 4 mm extension of a scribe after 500 hours salt-spray-test. The coatings showed no visible traces of abrasion after 1000 cycles taber abrader test and an excellent adhesion (cross cut and tape-test: grade 0). The transparent basic systems were pigmented by 5 - 10 wt.% of colored organic pigments to obtain all kind of colored coatings.
    Notes: Es wurde ein neuer Beschichtungswerkstoff auf Basis von anorganisch-organischen Kompositen zum Schutz von Metalloberflächen, besonders von Aluminium entwickelt. Das Beschichtungsmaterial wurde über den Sol-Gel-Prozeß synthetisiert, ausgehend von Epoxy-funktionalisierten Alkoxysilanen und aromatischen Diolen als Quervernetzer. Als Lösungsmittel wurden Alkohole und Glykolether verwendet.Die Viskosität der Systeme wurde so eingestellt, daß sowohl Sprüh-, als auch Tauch- und Flut-Beschichtungen durchgeführt werden konnten. Sie lag zwischen 7 und 55 mPas. Nach dem thermischen Verdichtungsprozeß bei 100-220°C wurden transparente Beschichtungen mit ausgezeichneter Haftung auf Al-Mg-, Zn-und Messing-Oberflächen (Gitterschnitt- und Tape-Test: Klasse 0) erhalten. Die Korrosionsfestigkeit beschichteter Aluminiumlegierungen (Al 99.5, AlMg3, AlMgSi I) wurde mit dem Salzsprühverfahren (DIN 50021) und dem CASS-Test (NaCl, CuCl2·2H2O, Essigsäure, pH=3) geprüft und auch nach 3000 Stunden trat keine Unterwanderung der Grenzfläche Metall / Schicht auf. Ebenso wurde keine „Filiform“-Korrosion beobachtet. Messingproben zeigten nach 500 h Salzsprühnebel-Test weniger als 4 mm mittlere Unterwanderungsbreite. Darüber hinaus wurde die Abriebbeständigkeit der Proben überprüft. Die Schichten zeigten keine sichtbare Beschädigung nach Prüfung des Abriebes mit dem Reibradverfahren (1000 Zyklen, Räder: CS 10-F).Es konnten stabile Dispersionen von organischen Farbpigmenten im transparenten Basissystem hergestellt werden, wodurch eine große Vielfalt farbiger Beschichtungen erhalten wurde.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19980290108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Reinforcement of amorphous thermoplastics by blending with a para-linked aromatic LC-polyester (1990)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 1 (1990), S. 143-150 
    Details
    ISSN: 1042-7147
    Keywords: Reinforcement ; Amorphous ; Matrix ; LC-polyester ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The preparation and the mechanical properties of binary blends of amorphous thermoplastics and a para-linked liquid crystalline polyester, which is expected to act as a reinforcement, are reported. The LC-polyester has the advantage that it is soluble in common organic solvents, that it has a low transition temperature, and that it does not crystallize readily. Polycarbonate, polystyrene, poly(methyl methacrylate), and poly(ether sulfone) were selected as matrix materials. Most of the films cast from the blends turned out to be turbid and thus phase separated, the sizes of the dispersed phases ranging between 0.2 μm (in polycarbonate) and 1 μm (in polystyrene).The LC-polyester causes a substantial increase of the stiffness in blends with polycarbonate, poly(methyl methacrylate), and poly(ether sulfone) and almost no increase in the case of polystyrene. These differences are attributed to the particular magnitudes of the strength of the phase coupling between the matrix and the dispersed phase, which is controlled by their compatibility.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1990.220010204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Excimer laser micromachining (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 2 (1993), S. 87-92 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The machining of several materials such as polymers, metals and ceramics using excimer lasers (193, 248 and 308 nm) was investigated. By photoablation, micrometer resolution can be achieved for polymers if the wavelength and fluence are chosen properly. High-definition processing of metals is complicated by the occurrence of surface melting. An interaction between the ablation plume and the walls of the laser-drilled holes leads to hole widening in the case of polymers at high fluences. For small structures (〈100 μm) all materials investigated show a size-dependent ablation rate. This effect has to be taken into account if a precise ablation depth is required for a pattern with structures of different sizes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860020111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Photochromic Organic-Inorganic Nanocomposites as Holographic Storage Media (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 123-133 
    Details
    ISSN: 1057-9257
    Keywords: nanocomposites ; sol-gel ; heteropolymetallates ; photochromics ; holographic data storage ; amplitude grating ; two-wave-mixing recording ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: This paper describes the properties of some new organic-inorganic photochromic layers. They are based on a hybrid organic-inorganic matrix in which tungsten heteropolyoxometallates (SiW12O4-40, PW12O3-40) are entrapped in a network obtained from the reaction of 3-glycidoxy-propyltrimethoxysilane. The high homogeneity of these materials on the nanoscale leads to transparent monoliths and layers of controlled thicknesses up to 40 μm. The optical properties of the blend are emphasised and the construction of amplitude gratings in the materials by two-wave-mixing experiments is described. The results of the optical experiments and the comparison with the theoretical background are used as a model for photochromic holographic storage processes. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...