Sample records for zyklisch nukleotid-gesteuerte ionenkanaele

  1. Search after new agents for hyperpolarization-activated and cyclic nucleotide-gated ion channels; Suche nach neuen Wirkstoffen fuer Hyperpolarisationsaktivierte und zyklisch Nukleotid-gesteuerte Ionenkanaele

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    Struenker, T.


    Rhythmic activity of single cells or cellular networks is a common feature of most organisms. Cellular rhythms govern the beating of the heart, cycles of sleep and wakefulness, breathing, and the release of hormones. The endogenous rhythmic activity of many neurons and cardiac relies on a complex interplay between several distinct ion channels. In particular, one type of ion channel plays a prominent role in the control of rhythmic electrical activity because it determines the frequency of the oscillations. The activity of the channels is thus setting the ''pace'' of the activity; therefore, these channels are often referred to as ''pacemaker'' channels. Despite their obvious physiological importance it hasn't been until a few years ago that the genes encoding pacemaker channels have been identified. Because both hyperpolarization and cyclic nucleotides are key elements that control their activity, pacemaker channels have now been designated hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels. From a scientific as well as medical point of view, HCN channels are interesting drug targets. Only a few substances are known that specifically affect HCN channels. In the present study, a microtiter plate-based high throughput screening assay for HCN1 and HCN4 channels was developed. With this assay, known drugs for HCN channels were characterized. Subsequently, venoms of snails, spiders, scorpions, and snakes were screened for toxins affecting HCN channel activity. A few venoms were identified that possibly contain drugs that act on HCN channels. (orig.)

  2. Zyklischer Vitalismus

    DEFF Research Database (Denmark)

    Halse, Sven


    Der ”Vitalismus” hat sich in den letzten Jahren in Teilen der skandinavischen Forschung als kulturanalytischer Begriff durchgesetzt. Er wurde in erster Linie für die Identifikation und Charakteristik der stärke-, gesundheits- und schönheitspreisenden Kunstströmung zwischen 1890 und1930 verwendet...

  3. Crack initiation and crack growth in high temperature materials under cyclic thermal stresses; Rissinitiierung und Risswachstum in Hochtemperaturwerkstoffen unter zyklisch thermischer Beanspruchung

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    Gruen, C.


    The high temperatures of use in drive units, such as the combustion chamber or the hot gas turbine, for example, usually cause high temperature changes. Great temperature differences occur for short periods in the components, and thermal shock is produced. In this work, theoretical and experimental investigations are introduced on crack initiation and crack growth in high temperature materials under cyclic thermal stresses. The experiments were carried out with the inter-metallic phase Ni{sub 3}Al, the nickel-based alloy Nimonic 80A and the iron-based alloy PM 2000 strengthened by oxide dispersion (ODS). A characteristic crack appearance picture was found for each material, which was examined more closely. The stresses occurring in the sample during one cycle were calculated with the aid of the finite element program ABAQUS, knowing the specific material parameters. Based on the linear-elastic fracture mechanics, stress intensity factors were calculated on the superimposition principle. Using the material data from isothermal crack propagation experiments, the prediction of fatigue crack spread with cyclic thermal stresses is compared with the experimental findings. (orig./AKF) [Deutsch] Die hohen Einsatztemperaturen in Antriebsaggregaten wie z.B. der Brennkammer oder der Heissgasturbine bedingen in der Regel hohe Temperaturwechsel. Dabei treten kurzzeitig grosse Temperaturunterschiede in den Bauteilen auf, ein Thermoschock wird erzeugt. In der vorliegenden Arbeit werden theoretische und experimentelle Untersuchungen zur Rissinitiierung und zum Risswachstum in Hochtemperaturwerkstoffen unter zyklisch thermischer Belastung vorgestellt. Die Experimente wurden mit der intermetallischen Phase Ni{sub 3}Al, der Nickelbasislegierung Nimonic 80A und der oxid-dispersionsverfestigten (ODS) Eisenbasislegierung PM2000 durchgefuehrt. Fuer jeden Werkstoff stellte sich ein charakteristisches Risserscheinungsbild dar, das naeher untersucht wurde. Die in der Probe auftretenden

  4. Examination of influencing factors on cyclic crack growth behaviour of cracked components. Final report; Untersuchung von Einflussfaktoren auf das zyklische Risswachstum angerissener Bauteile. Abschlussbericht

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    Soppa, Ewa Anna; Silcher, Horst


    Fatigue crack growth of short and long cracks was investigated for both materials: the Nb-stabilized austenitic stainless steel X6 CrNiNb 18-10 and the ferritic-bainitic steel 22 NiMoCr 3-7. These both steels belong to the materials in the primary circuit of german power plants. For a reliable estimation of the lifetime of components subject to cyclic fatigue a detailed knowledge of the phenomena accompanying fatigue processes and which cause both - initiation and growth of fatigue cracks is essential. The deformation induced transformation of austenite into α'-martensite at room temperature is thus very important in the initiation and growth of fatigue cracks. Because these processes are manifest at first at the microlevel, the use of methods which reveal information at high resolution is of significant importance. In order to study the initiation and growth of short cracks, cylindrical smooth specimens, compact tension C(T)- and modified C(T)-specimens have been used. Cyclic crack propagation of long cracks was investigated on compact tension C(T)-specimens with W=50 mm and B=10 mm. The SEM, TEM and EBSD technique are powerful methods for determining crystallographic orientation, for the identification of individual phases and for recealing plastic deformation. They were used for analyses of microcracks in combination with interrupted cyclic tests. The impact of crack closure on the threshold parameter ΔK{sub th} and the crack growth rate da/dN was investigated experimentally for the growth of long cracks under cyclic loading for different R-values at room temperature. Additional tests were performed at T=288 C in order to investigate the role of temperature on crack growth rates. The effect of overloads in tension and compression as another factor influencing the crack growth was also studied. Measured crack growth curves were fitted using Paris and Erdogan-Ratwani law as well as the NASGRO-equation. Fracture surfaces of selected specimens for both steels were investigated in SEM in order to find out the differences between austenitic and ferritic-bainitic structures. The experimental results for cyclic crack growth behaviour have been compared with the reference curves for ferritic and austenitic steels in ASME XI Code.

  5. Microfractographic analysis of delamination growth in fatigue loaded - carbon fibre/thermosetting matrix composites; Mikrofraktographische Analyse des Delaminationswachstums in zyklisch belasteten Kohlenstoffaser/Duroplastharz-Verbundwerkstoffen

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    Heutling, F.; Franz, H.E. [Daimler-Benz AG, Muenchen (Germany); Friedrich, K. [Kaiserslautern Univ. (Germany). Inst. for Composite Materials Ltd.


    Carbon-fibre-reinforced plastics (CFRP) are known to be considerably less sensitive to fatigue loading than aluminium (Al) alloys, for instance. However, even in the presence of small delaminations, the damage tolerance of structural components may be considerably reduced. The scope of the present contribution is to investigate fatigue phenomena in CFRP materials (with thermosetting matrix) by means of microfractography. The microfractographic features of the fracture surfaces mirror the processes of deformation and fracture at the delamination front. The fatigue fracture behaviour of a CFRP laminate subjected to cyclic mixed-mode loading is determined by matrix-controlled failure mechanisms. Under pure mode-II loading conditions, rollers in addition to fatigue striations appear in the fibre imprints whose formation mechanism was explained by means of high-resolution field-emission scanning electron microscopy (FE-SEM). The ratio between the local tensile and shear stress components influences the propagation direction of secondary cracks originating at the fibres. The local fracture propagations in these secondary cracks can be recognised through the fatigue striations appearing on the surface of the matrix. A comparison with static mixed-mode loading reveals that in both cases the crack propagation follows the path of the local maximum main stress. Applying mathematical relationships derived from the theory of elasticity permitted developing a mixed-mode loading model which makes it possible to predict the crack processes and hence to explain the formation of typical fracture-morphological features. (orig.) 26 refs.

  6. Characterization of cyclic deformation behaviour by mechanical, thermometrical and electrical methods; Bewertung zyklischer Verformungsvorgaenge metallischer Werkstoffe mit Hilfe mechanischer, thermometrischer und elektrischer Messverfahren

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    Pietrowski, A. [Essen Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Werkstoffkunde; Eifler, D. [Kaiserslautern Univ. (Germany). Lehrstuhl fuer Werkstoffkunde


    Cyclic deformation causes changes in the microstructure and subsequently failure of structural parts. Mechanical, thermometrical and electrical methods can be used to characterize the deformation behaviour of metals as can be shown for normalized or heat treated steels as well as for sintered steels. (orig.)

  7. Influence of bondcoat composition and manufacturing parameters on the lifetime of thermal barrier coatings under cyclic temperature loading; Einfluss der Bondcoatzusammensetzung und Herstellungsparameter auf die Lebensdauer von Waermedaemmschichten bei zyklischer Temperaturbelastung

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    Subanovic, Marko


    In the present study the influence of the bond coat composition on the lifetime of thermal barrier coatings during thermal cycling was investigated. The knowledge, that the reactive elements (RE), which are essential for the improvement of the oxide scale adhesion, are ''lost'', during the bond coat processing, made it necessary to investigate systematically the influence of the different manufacturing stages on the RE distribution. After VPS (vacuum plasma spraying) with a high oxygen partial pressure in the spraying chamber, the reactive elements in the NiCoCrAl-coating were tied up in oxide precipitates, and thus their beneficial effect on the scale adhesion was inhibited. Another important observation is that the RE's are depleted during the bondcoat vacuum heat-treatment. The degree of Y-depletion depends not only on the Y-reservoir in the coating (Y-content and thickness) but also on the heat-treatment parameters, such as vacuum quality and temperature. A thin, dense alumina oxide scale with a smooth interface between bond coat and TGO doesn't necessary lead to a lifetime extension of the EB-PVD TBC's. TBC's with such oxide morphology typically failed due to crack formation and propagation along the interface between the TGO and the bondcoat. By addition of zirconium it was possible to shift the failure initiation from the interface TGO/bondcoat to the interface TBC/TGO, which can apparently accommodate more thermal strain energy before failure. The shift of the failure location was achieved by a change of the oxide morphology, which mainly relies on adjusting a non-even wavy interface between the TGO and the bond coat and formation of defected oxide layers. In contrast, a defected oxide scale with a high growth rate shortened the life time of APSTBC's. Porosity and spinel formation weakened the mechanical integrity of the oxide scale, and facilitated the crack formation and propagation of the already existing cracks. The potential to improve lifetimes of APS-TBC's should arise from an adjustment of optimal interface roughness between TBC and bond coat, a TBC morphology with defect perpendicular to the crack propagation direction, formation of oxide scales with a low defect density and growth rate, ''strong'' interface between bond coat and oxide. Additionally the influence of water vapour-containing and reducing, water vapour/hydrogenatmospheres, as may prevail in power generation systems with CO2 separation, on the oxidation behaviour of MCrAlY alloys was investigated. In water vapour containing atmospheres the hydrogen increases the weight gain by increasing the solubility and diffusivity of oxygen in the alloy. Similar observations were made in strongly reducing atmospheres (e.g. Ar-4%H{sub 2}-2%H{sub 2}O). In this case the alumina growth rate was decreased, but the internal oxidation of yttrium due to hydrogen effect was even more pronounced. Another important observation was the tendency of freestanding MCrAlY coatings to blister when exposed in water vapour containing atmospheres with hydrogen additions. It seems that recombination of solute hydrogen at defects in the material interior is responsible for a pressure build-up in the blisters. Suitable measures to prevent hydrogen-induced damage would be a choice of material with low hydrogen solubility, high mechanical strength or application of a coating technology, which introduces fewer defects in the coating. An alternative measure would be a reduction of the yttrium reservoir in the coating because barrier properties of alumina scales against hydrogen are deteriorated by precipitation of yttrium-rich oxide phases in the TGO. (orig.)

  8. Experimentelle, analytische und numerische Untersuchungen des Rührreibschweißprozesses


    Hoßfeld, Max


    Mit dem Rührreibschweißverfahren steht seit einigen Jahren eine Fügetechnologie zur Verfügung, mit der viele fügetechnische Problemstellungen speziell beim Fügen von Aluminiumlegierungen gelöst oder vermieden werden können. Mittels Rührreibschweißen können sämtliche Aluminiumlegierungen zuverlässig, hocheffizient und mit einem sehr hohen Verbindungswirkungsgrad gefügt werden. Dabei weisen rührreibgeschweißte Verbindungen bereits ohne Nachbehandlung sehr gute statische und zyklische Festigkeit...

  9. Fatigue behaviour of metals. 2. ed.; Ermuedungsverhalten metallischer Werkstoffe

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    Christ, H.J. [Siegen Univ. (Gesamthochschule) (Germany). Inst. fuer Werkstofftechnik


    The book presents an outline of the fatigue characteristics of metals. Interested students, engineers, scientists and users are provided with a basic understanding of the possible processes, from which they will get a feeling for the processes going on inside materials under fatigue stress which is indispensable for developing and testing modern constructional materials. Subjects: Introduction and outline - Material fatigue and microstructure - Cyclic stress-strain behaviour - Cracking - Electron microscopy - Fundamentals of fracture mechanics - Fatigue crack growth - Cyclic strength of steels - Thermomechanical fatigue - Operating strength of components - Fatigue of welded constructions. [German] In dem vorliegenden Buch wird ein Ueberblick ueber die Ermuedung metallischer Werkstoffe gegeben. Interessierten Studenten, Ingenieuren, Wissenschaftlern und Anwendern wird ein Grundverstaendnis fuer die moeglichen Prozesse vermittelt, aus dem sich ein Gefuehl fuer die Vorgaenge im Werkstoff bei zyklischer Beanspruchung entwickelt - unabdingbar fuer Entwicklung und Pruefung moderner Kontruktionswerkstoffe. Es enthaelt folgende Themen: Einfuehrung und Ueberblick - Materialermuedung und Mikrostruktur - Zyklisches Spannungs-Dehnungsverhalten - Rissbildung - Elektronenmikroskopische Untersuchungen - Grundlagen der Bruchmechanik - Ermuedungsrisswachstum - Schwingfestigkeit von Staehlen - Thermomechanisches Ermuedungsverhalten - Betriebsfestigkeit von Bauteilen - Ermuedung von Schweisskonstruktionen.

  10. Metallography and quality of dies made from WC-Co cemented carbides; Metallographie und Qualitaetskontrolle von WC-Co-Hartmetallmatrizen

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    Forejt, M. [Inst. of Technology, Faculty of Mechanical Engineering, Technical Univ., Brno (Czech Republic); Krejcova, J. [Inst. of Technology, Faculty of Mechanical Engineering, Technical Univ., Brno (Czech Republic); Smutna, J. [Inst. of Physics of Materials, ASCR, Brno (Czech Republic); Krejci, J. [Inst. of Physics of Materials, ASCR, Brno (Czech Republic)


    As opposite to cutting tools made from cemented carbides, forming tools (dies) seem to be on the periphery of the interest, although specific loading conditions (increased temperature, relatively high strain rate, high pressure and cyclic loading) impose different requirements on the material. The present paper contains results of light and SEM metallography of WC + Co cemented carbide dies used for screw nuts production. Two problems were pursued viz. final preparation of the surface of operative cavity after drilling and defects that appear when recycled cemented carbides are used for die production. (orig.) [Deutsch] Im Gegensatz zu Hartmetall-Schneidwerkzeugen scheinen Formwerkzeuge (Matrizen) nur am Rande des Interesses zu liegen, obwohl hier die spezifischen Beanspruchungsbedingungen (hoehere Temperaturen, relativ hohe Dehnrate, hoher Druck und zyklische Belastung) zu besonderen Anforderungen an den Werkstoff fuehren. Es werden die Ergebnisse der lichtmikroskopischen und REM-Untersuchungen an WC-Co-Hartmetallmatrizen fuer die Mutternherstellung beschrieben. Zwei Themen werden behandelt, und zwar die Endbearbeitung der Formhohlraum-Oberflaeche nach dem Bohren und die Fehler, die durch die Verwendung von Hartmetallschrott fuer die Matrizenherstellung auftreten koennen. (orig.)

  11. Symptomatic endometriosis of the colon - a case report; Symptomatische Dickdarmendometriose - eine Falldarstellung

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    Leutloff, U.C. [Abt. Radiodiagnostik, Radiologische Universitaetsklinik Heidelberg (Germany); Roeren, T. [Abt. Radiodiagnostik, Radiologische Universitaetsklinik Heidelberg (Germany); Feldmann, K. [Abt. Gynaekologische Endokrinologie und Fertilitaetsstoerungen, Universitaets-Frauenklinik Heidelberg (Germany); Sillem, M. [Abt. Gynaekologische Endokrinologie und Fertilitaetsstoerungen, Universitaets-Frauenklinik Heidelberg (Germany); Rabe, T. [Abt. Gynaekologische Endokrinologie und Fertilitaetsstoerungen, Universitaets-Frauenklinik Heidelberg (Germany); Kauffmann, G. [Abt. Radiodiagnostik, Radiologische Universitaetsklinik Heidelberg (Germany)


    The intestinal endometriosis in need of treatment is a rare case in the surgical department. Preoperative diagnosis is very difficult and in any case must be based on histologic findings; endoscopy-guided biopsy very frequently yields negative results. Dual-contrast scanning of the colon still is a major examination method, but the findings make it difficult to rule out malignomas. Cyclic, recurrent abdominal complaints reported in the case history strongly indicate the possibility of endometriosis. Typing can be done in general only after surgery. The article reports the clinical and diagnostic parameters of a symptomatic endometriosis of the colon. (orig.) [Deutsch] Die behandlungsbeduerftige Darmendometriose ist eine seltene Erkrankung im chirurgischen Krankengut. Eine praeoperative Diagnose ist meist schwierig und ohne Histologie nicht zu erreichen; die endoskopisch gesteuerte Biopsie ist haeufig negativ. Eine grosse Rolle spielt nach wie vor die Kolonuntersuchung im Doppelkontrast, wobei die Abgrenzung zu einem Malignom schwierig ist. Einen wichtigen Hinweis liefern in der Anamnese zyklisch wiederkehrende abdominelle Beschwerden. Die Artdiagnose gelingt in der Regel erst operativ. Wir beschreiben die klinischen und diagnostischen Parameter einer symptomatischen Dickdarmendometriose. (orig.)

  12. Hydrogen diffusion into fatigue cracks of aluminium alloy 6013 in a corrosive environment; Wasserstoffeinlagerung an Ermuedungsrissen der Aluminiumlegierung 6013 unter korrosiver Umgebung

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    Lenk, Christian Alexander


    The author attempted a time-resolved detection of raised hydrogen concentrations in the plastic deformation region of fatigue cracks in an aluminium test piece deformed by cyclic stress in a corrosive environment. Mechanical material parameters like the crack propagation velocity under cyclic stress change dramatically in a corrosive environment. This is assumed to be caused by hydrogen diffusion, but so far there is no method that reliably measures additional hydrogen from the corrosive environment. For this reason, a special analytical configuration was set up which makes use of the thermal desorption method. First, chips with a thickness of about 20 micrometers are sawed out of the test specimen in high-vacuum conditions. The chips fall into a hot melting vessel in a UHV chamber, where the hydrogen contained in the chips is released. The resulting pressure increase is recorded by a mass spectrometer. A hydrogen profile of the test specimen is obtained by assigning the chip position to the signal. For the corrosive medium in which the test specimen is immersed during crack initiation, i.e. NaCl solution, heavy water was used. This makes it possible to distinguish between the hydrogen contained in a piece of technical aluminium alloy (AA6013) and the deuterium diffusing in from the corrosive fluid. The deuterium is found exclusively in the test piece volume in the strongly plastically deformed region surrounding the fatigue crack. (orig.) [German] Das Ziel der vorliegenden Arbeit besteht im ortsaufgeloesten Nachweis einer erhoehten Wasserstoffkonzentration im plastisch deformierten Bereich von Ermuedungsrissen einer unter korrosiver Umgebung zyklisch verformten Aluminiumprobe. Mechanische Materialparameter wie z.B. die Rissausbreitungsgeschwindigkeit unter zyklischer Belastung aendern sich drastisch in korrosiver Umgebung. Als Ursache fuer dieses Verhalten wird eine Eindiffusion von Wasserstoff vermutet, jedoch gibt es bisher keine Messung die den zusaetzlichen

  13. Fatigue behaviour of metallic materials; Ermuedungsverhalten metallischer Werkstoffe

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    Christ, H.J. [ed.


    The 16 contributions selected for this book, each from experts in their fields, are intended to give a broad survey of the phenomenon and mechanisms of fatigue in metallic materials, addressing important aspects and showing the cross-disciplinarity of scientific research required to obtain a complete picture. Emphasis has been placed on the matter being discussed in a way that is easy to digest as well as complete in information, which was possible only by deliberate restriction to the essential knowledge available today, leaving aside what recent scientific research may have revealed, or whatever interesting specific aspects there may be. The known mechanisms of fatigue and their effects in metallic materials as well as the conclusions to be drawn from the engineering angle with regard to the applicability of the materials and systems design are the points of main interest of the book, which offers readers to develop a sound, general understanding of the processes involved and a feeling for the effects induced in the materiuals by cyclic stress. (orig./CB) [Deutsch] In diesem 16 Fachbeitraege enthaltenden Buch wird versucht, einen ueberschau- und erfassbaren Ueberblick ueber die Ermuedung metallischer Werkstoffe unter Beruecksichtigung der wichtigen Teilaspekte und Wissenschaftsgebiete darzustellen. Die Betonung wird bewusst auf Verstaendlichkeit und Uebersichtlichkeit gelegt, was nur durch Einschraenkung der Breite der Behandlung und durch Verzicht auf neueste wissenschaftliche Details moeglich ist. Im Vordergrund stehen die bei der Ermuedung ablaufenden werkstoffkundlichen Vorgaenge und die sich daraus ergebenden Konsequenzen fuer den Werkstoffeinsatz und die -auslegung. Primaer soll ein solides Grundverstaendnis fuer die moeglichen Prozesse vermittelt werden, aus dem sich ein Gefuehl fuer die Vorgaenge im Werkstoff bei zyklischer Beanspruchung entwickeln kann. (orig.)

  14. Study of colored anodized aluminum with calcon in sulfuric acidic solution using cyclic voltammetry and impedance measurement methods

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    Norouzi, P.; Ganjali, M.R.; Golmohamaddi, M.; Mousavi, S. [Department of Chemistry, Faculty of Science, University of Tehran, Tehran (Iran); Vatankhah, G. [Iranian Organization for Science and Technology (IROST), Isfahan Center, A5 Ghezelbash Avenue, Tohid Street, Isfahan 8173954541 (Iran)


    The effect of coloring condition of Al with Calcon (sodium 2,2'-dihydroxy-azonaphthalene-4-sulfonate), on the corrosion resistance of Al in 0.1 M sulfuric acid solution was studied, using cyclic voltammetry and measurement of impedance noise methods. The changes in the corrosion resistance of colored aluminum electrodes were evaluated by measuring the magnitude of impedance and cyclic voltammetric responses of anodized and colored electrodes. An irreversible corrosion response was observed at the cyclic voltammogram of the colored aluminum electrode. The current and threshold potential of corrosion responses strongly depends on the applied conditions during anodizing, coloring and sealing stages. In addition, significant changes in impedance at the ac voltammogram and noise level at some ac frequencies were observed, when the electrodes were colored under various conditions. In this regard, the surface of the electrode was studied by Scanning Electron Microscopy (SEM). Comparison of SEM images of the colored and uncolored aluminum specimens showed that the colored surface contained a significant numbers of pits. The results indicated that coloring aluminum with Calcon could reduce corrosion resistance of aluminum and increase roughness of the oxide film. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Mit Hilfe zyklischer Voltammetrie und Messungen mit Impedanzrauschmethoden wurde der Einfluss der Faerbungsbedingungen von Aluminium mit Calcon (Natrium 2,2'-Dihydroxyazonaphthalen-4-Sulfonat) auf den Korrosionswiderstand von Aluminium in 0,1 M Schwefelsaeure untersucht. Die Veraenderungen des Korrosionswiderstandes von gefaerbten Aluminiumelektroden wurden durch Messungen der Hoehe der Impedanzreaktion bzw. der Reaktion bei der zyklischen Voltammetrie von anodisierten und gefaerbten Elektroden beurteilt. Eine irreversible Korrosionsreaktion wurde beim zyklischen Voltammogramm der gefaerbten Aluminiumelektrode beobachtet. Der Strom und das

  15. Improving crack counterbalanced sucker rod pump units; Ueberlegungen zum dynamischen Drehmomentenausgleich von Tiefpumpenantrieben

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    Kessler, F. [Montanuniversitaet Leoben (Austria). Inst. fuer Konstruktionslehre


    Counterbalancing the torque at the gearbox, resulting from the load at the polished rod and the geometry of the unit, is still a significant design and operational problem. In this article well known crank-counterbalanced units are briefly described and a new unit, with an additional crank counterbalance system, is introduced. The counterweights on the cranks always create a sinusoidal torque distribution over one cycle. Applying the arithmetic method of non linear regression to the torque distribution, which results from the load at the polished rod, a most closely matching sinussoidal curve can be calculated. This curve shows the optimum phase angle and counterweight torque value and therefore a quick adjustment of the counterweights can be made. With the same arithmetic method, phase angle and counterweight value of the additional crank counterbalance is established. A comparison between a conventional unit and one with an additional counterbalancesystem has shown, that in the second case, the acting gearbox torque is up to 50% lower than in the first case. This allows the use of smaller gearbox and prime mover. From the technical point of view the additional counterbalance system is an excellent development enabling the acting-gearbox torque to be reduced. System set-up requires only a simple computer program and careful operator implementation. (orig.) [Deutsch] Der Ausgleich des zyklisch schwankenden Antriebsdrehmomentes stellt fuer die Auslegung und den Betrieb von Tiefpumpenantrieben ein zentrales Problem dar. In der vorliegenden Arbeit werden einleitend die bekannten Antriebsbauarten mit dynamischem Drehmomentenausgleich beschrieben und eine neue Bauart mit zusaetzlichem Ausgleich vorgestellt. Die Lasten am Pferdekopf verursachen an der Kurbel (Getriebeausgang) ein Drehmoment, das als Bruttodrehmoment bezeichnet wird. Das Ausgleichsdrehmoment zur Verringerung des Bruttodrehmomentes ist jenes Moment an der Kurbel, das durch die rotierenden

  16. MARCKO thermal insulation layers. Life predictions for thermal insulation and antioxidant layers. Final report; MARCKO-Waermedaemmschichten. Methoden zur Lebensdauervorhersage von Waermedaemm- und Oxidationsschutzschichten. Schlussbericht

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    Schuetze, M.


    , Rolls-Royce und Siemens als Industriepartner und FZ-Juelich, DLR und DECHEMA als Institute beteiligt waren, wurden Arbeiten zur Entwicklung eines Lebensdauermodells fuer einkristalline, keramisch beschichtete Gasturbinenschaufeln durchgefuehrt. Dieses Modell soll zuverlaessige Voraussagen ueber die Zeitdauer der Haltbarkeit der Keramik und der Haftvermittlerschicht unter verschiedenen Betriebsbedingungen ermoeglichen. Die Aufgabe des Karl-Winnacker-Instituts der DECHEMA e.V. im Rahmen dieses Verbundprojektes bestand zunaechst in isothermen Oxidationsversuchen, die bei 950 C-1100 C an Laborluft durchgefuehrt wurden. Anschliessend wurde das Oxidationsverhalten anhand von metallographischen Schliffen charakterisiert. Dabei wurde besonderes Augenmerk auf die Entwicklung der TGO (Thermally Grown Oxide)-Schichtdicken, der oxidschichtseitigen Aluminiumverarmung im Bond Coat sowie der physikalischen Defekte in Form von Poren, Porenpopulationen und Mikrorissen innerhalb bzw. in unmittelbarer Naehe der TGO gelegt. Erstmalig wurden diese Mikrorisse postexperimentell anhand von rasterelektronenmikroskopischen Aufnahmen klassifiziert und die maximalen Abmessungen solcher Risse in Abhaengigkeit der Auslagerungsdauer quantifiziert. Fuer alle diese Parameter wurden Kinetiken ermittelt. Weiterhin wurden wachstumsinduzierte, laterale Spannungen in der TGO anhand der Durchbiegung einer duennen Metallfolie aus reinem Bond Coat Material bestimmt. Im Rahmen eines Unterauftrags von Projektpartner Rolls-Royce wurde das mechanische Verhalten APS-gespritzter Waermedaemmschichten mittels uniaxialer Druckversuche an freistehenden, hohlzylindrischen Ringproben anwendungstypischer Dicke bei Raum- und Anwendungstemperatur untersucht. Einerseits wurde das thermoelastische Verhalten mittels weggeregelter, zyklischer Belastungsversuche ermittelt, andererseits wurde das thermoplastische Verhalten anhand von lastgeregelten Kriechexperimenten bestimmt. Um den Einfluss einer vorhergehenden