Femtosecond laser ablation of cemented carbides: properties and tribological applications

Laser ablation with fs laser pulses was performed in air on cobalt cemented tungsten carbide by means of a Ti : sapphire laser (800nm, 100fs). Small and moderate fluences (2, 5, 10J/cm2) and up to 5×104 pulses per irradiated spot were used to drill holes with aspect ratios up to 10. Cross-section cuts from laser-irradiated samples were produced and they were analysed with optical microscopy and SEM. EDX analyses were carried out on selected zones. Quasi-cylindrical holes were found for 2J/cm2, whereas for 5 and 10J/cm2 irregular shapes (lobes, bottoms wider than hole entrances) were found to occur after a given number of incident pulses. Layers with modified structure were evidenced at pore walls. SEM revealed a denser structure, while EDX analyses showed uniform and almost similar contents of W, C, and Co in these layers. As a direct application, patterning of coated WC-Co was carried out with 2J/cm2 and 100 pulses per pore. The resulted surfaces were tribologically tested and these tests revealed an improved friction and wear behaviou

A theory of Plasma Membrane Calcium Pump stimulation and activity

The ATP-driven Plasma Membrane Calcium pump or Ca(2+)-ATPase (PMCA) is characterized by a high affinity to calcium and a low transport rate compared to other transmembrane calcium transport proteins. It plays a crucial role for calcium extrusion from cells. Calmodulin is an intracellular calcium buffering protein which is capable in its Ca(2+) liganded form of stimulating the PMCA by increasing both the affinity to calcium and the maximum calcium transport rate. We introduce a new model of this stimulation process and derive analytical expressions for experimental observables in order to determine the model parameters on the basis of specific experiments. We furthermore develop a model for the pumping activity. The pumping description resolves the seeming contradiction of the Ca(2+):ATP stoichiometry of 1:1 during a translocation step and the observation that the pump binds two calcium ions at the intracellular site. The combination of the calcium pumping and the stimulation model correctly describes PMCA function. We find that the processes of calmodulin-calcium complex attachment to the pump and of stimulation have to be separated. Other PMCA properties are discussed in the framework of the model. The presented model can serve as a tool for calcium dynamics simulations and provides the possibility to characterize different pump isoforms by different type-specific parameter sets.Comment: 24 pages, 6 figure

Poly(diacetylene) Monolayers Studied with a Fluorescence Scanning Near-Field Optical Microscope

A novel and powerful method to study the optical properties of thin lipid films which a resolution superior to confocal microscopy is presented. With a scanning near-field optical microscope, fluorescence images of a Langmuir-Blodgett film of diethylene glycol diamine pentacosadiynoic amide are obtained with a lateral resolution of 100 nm. Simultaneously a force image is measured that gives the topography. Therefore it is possible to correlate a high-resolution fluorescence micrograph with the topological structure of the polymer film. Polymer domains that do not fluoresce are visible in the force image, while polarization dependence, an optical property not afforded by atomic force microscopy, is clearly demonstrated with a high resolution in the near-field optical image. This combination of fluorescence scanning near field optical microscopy and force microscopy provides additional information o­n the structure of the polymer film that can be valuable in the research of Langmuir-Blodgett film

Organisational bases of the electricity supply industries in the member states of the European Community

Translated from GermanSIGLEAvailable from British Library Document Supply Centre- DSC:6196.3(OA-Trans--2954)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Theoretische Bewertung, Konditionengestaltung und Marktpreisbildung innovativer Finanzierungsinstrumente

SIGLEBibliothek Weltwirtschaft Kiel C 153266 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren. Programmbudget 1997

The Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren, which was founded in 1995 as the successor of the Association of Government-sponsored Research Centers in Germany, publishes in this report its programme budget for 1997 and information on activities and commitments receiving support in the following selected research areas: energy research and energy technology; transportation and traffic systems, space technology and applied research for use of outer space; research into terrestrial systems; environmental research; research to the service of public health; biotechnology; information and telecommunications technology; new materials and technologies; research into the fundamentals of matter. Concluding sections list national and international cooperations as well as research activities, budgets and personnel of the various research centers for the period of the year 1997. (RHM)Die Hermann von Helmholz-Gemeinschaft Deutscher Forschungszentren, 1995 aus der Arbeitsgemeinschaft der Grossforschungseinrichtungen entstanden, dokumentiert im vorliegenden Programmbudget ihre Aktivitaeten in den Schwerpunkten Energieforschung und Energietechnologie; Transport- und Verkehrssysteme, Weltraumnutzung und Raumfahrttechnik; Erdsystemforschung; Umweltforschung; Forschung im Dienste der Gesundheit; Biotechnologie; Informations- und Kommunikationstechnik; neue Materialien und Technologien; Erforschung der Grundlagen der Materie. Abschliessend werden nationale und internationale Kooperationen aufgelistet sowie die Forschungsschwerpunkte, Finanzierung und Personaleinsatz der Forschungszentren fuer 1997 angegeben. (RHM)SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Deactivation of regulatory proteins hnRNP A1 and A2 during SC-1 induced apoptosis

Phosphorylation and activation of caspases play an important role in the induction of apoptosis. During tumor specific apoptosis, induced by the human monoclonal antibody SC-1, tyrosine phosphorylation and serine dephosphorylation of several proteins is observed. In this paper we describe the identification of two dephosphorylated proteins as heterogeneous nuclear ribonucleoproteins A1 and A2 (hnRNP A1, hnRNP A2). The dephosphorylation of these proteins is important for apoptosis since the amount of apoptotic cell death can be decreased by the specific serine/threonine phosphatase inhibitor okadaic acid. We also investigated the effect of serine kinase inhibitor H7 on SC-1 induced apoptosis, which leads to a dose dependent increase in apoptosis. We could also show that 24 hours after the induction of apoptosis the hnRNP A1 protein is cleaved into different cleavage products. Further, we found a decreased expression of caspase-2 in early apoptosis signalling and an overexpression 24 hours after induction of apoptosis. Our results show that the phosphorylation status of the hnRNP A1 and A2 plays a significant role in early SC-1 induced apoptosis signalling and further indicate the role of caspase activation during the apoptotic process