Schädigungsentwicklung der Legierung IN 738 LC bei Hochtemperatur-LCF-Beanspruchung

Damage evolution of the alloy IN 738 LC at high temperature low cycle fatigue Herrn Professor K.-T. Rie zum 60. Geburtstag Interrupted Low-Cycle-Fatigue tests have been carried out with IN 738 LC at 850°C. The specimens were extensively examined by SEM to quantify the evolution of fatigue damage. Surface crack nucleation at oxidized grain boundaries occured during the whole experiments. The coalescence of cracks was the dominant mechanism which lead to macro crack evolution and the final fracture.     

The radioecology of the grapevine. 1. The transfer of nuclear weapons fallout from the soil into wine

In a field investigation (1983-1985) comprising eight places of the most important viticultural regions in the Federal Republic of Germany, the contents of the radionuclides tritium (3H), carbon-14 (14C), strontium-90 (90Sr), and cesium-137 (137Cs) in air, soils, leaves of the vine, grapes and wine were measured and site-specific transfer factors were calculated. Data concerning soil parameters, climatic conditions, cultivation and vinification were collected. The tritium content of all samples was 10 Bq/l water of combustion, independent of location and year. The specific activity of 14C in the atmosphere and in biological material was 0.22 Bq/g carbon, independent of site and year. 90Sr contents of soils fluctuated between 0.7 and 3.5 Bq/kg dry matter. The mean content of leaves was 2 Bq/kg fresh material, of grapes 0.035 Bq/kg and of wine 0.008 Bq/l. 137Cs content of soils fluctuated between 1.3 and 7.9 Bq/kg dry matter. The mean content of leaves was 0.098 Bq/kg fresh material, of grapes 0.021 Bq/kg and of wine 0.0085 Bq/l. A relation between transfer of radionuclides and soil parameters and between the contents of grapes and wine was not recognizable. While cultivar-specific differences were not observed in grapes, red wines contained somewhat more 137Cs than white wines. Transfer factors soil grapes were 0.027 for 90Sr and 0.0057 for 137Cs. Site-specific influences such as soil parameters, climate, cultivation, vinification and differences between years led to a relatively small fluctuation of values. An influence of the nuclear power station Neckarwestheim has not been found in any of the radionuclides.     

An integrated population,economic, and water resource model to address sustainable development questions for Botswana

Abstract:

An integrated population, economic, and water resource model was developed to address sustainable development questions for Botswana. raditionally, water resources planning models have considered the implications of different assumptions of population and economic growth on the sustainability of existing water resources supply; however, this model extends that capability to consider feedbacks from one model component to another. For example, the model has the unique capability to examine implications of changing water‐related diarrhea incidence on the health of the HIV/AIDS population. Investments in water supply and sanitation or in HIV/AIDS medication impact the health and productivity of the population. The water model uses a physically‐based hydrologic rainfall‐runoff model with surface and groundwater components to produce monthly runoff and groundwater recharge at the watershed scale. Botswana is divided into socioeconomic regions, and the water resources infrastructure is characterized by virtual reservoirs in each. The demographic sub‐model is a standard multi‐cohort model that forecasts the population by age, sex, rural or urban residence, education level, and HIV/AIDS status. The economic sub‐model is a computable general equilibrium model with three components: agriculture, non‐agricultural exports, and non‐tradables. The model runs an ensemble of scenarios, including climate change, HIV/AIDS, health, economic, and water conservation scenarios, whose output is probabilistic in nature. The three model components are described, with particular emphasis on the model linkages and the water sub‐component, and results are shown for a variety of scenarios.     

Mechanismen der Korrosionsinhibition im Vergleich zu den Inhibitionsmechanismen anderer Elektrodenreaktionen

Corrosion inhibition mechanisms as compared to the inhibition mechanisms of other electrode reactions The corrosion inhibition is a special case of the inhibition of electrochemical electrode reactions. During any reaction of this nature - with or without impressed current - partial reactions may be inhibited by boundary face, electrolyte film or membrane inhibitors. The boundary face inhibitors are most efficient in acid or alkaline media, while membrane inhibitors are most efficient in approximately neutral media. The former — because of electrosorption at the metal/electrolyte boundary face - affect the electrochemical charge exchange or heterogeneous chemical partial reactions, while membrane inhibitors inhibit all the partial reactions by building a threedimensional surface layer. The electrolyte film inhibitors inhibit mass transfer to or from the metal/electrolyte boundary face, or they inhibit homogeneous chemical partial reactions either mechanically (by colloids or suspensions) or electrochemically (by modifying the surface charge of the metal and thus the tranfer velocity of ions by increasing attraction or repulsion). The use of passivators is restricted exclusively to corrosion inhibition. The passivating layers formed by them are much thinner and denser than the layers formed by membrane inhibitors. The passivators act like boundary surface inhibitors.     

Trägheitsfreie Schnittkraftmessung beim Holzfräsen

Zusammenfassung Auf Grund der gezeigten Beispiele der tr?gheitsfreien Schnittkraftmessung ist ersichtlich, da? damit praktisch wichtige Fragen der Holzzerspanung aufgegriffen werden k?nnen. Darunter fallen: Ermittlung des maximalen Kr?fteverlaufs für die Beanspruchung des Werkzeugs und für das Rückschlagverhalten des Holzes; Festlegung der optimalen Schneidengeometrie (Winkel und Zahl der Schneiden)—Einflu? der Schneidensch?rfe; Ermittlung des Schnittgeschwindigkeitseinflusses hinsichtlich der auftretenden Kr?fte, der Standzeit des Werkzeugs und der erzielbaren Oberfl?chengüte. Vortrag, gehalten auf der Arbeitstagung der Fachausschüsse Holzhe- und verarbeitung der Deutschen Gescllschaft für Holzforschung am 27. April 1954 in Bad Homburg.     

Non-invasive optical imaging of stroke

The acute onset of a neurological deficit is the key clinical feature of stroke. In most cases, however, pathophysiological changes in the cerebral vasculature precede the event, often by many years. Persisting neurological deficits may also require long-term rehabilitation. Hence, stroke may be considered a chronic disease, and diagnostic and therapeutic efforts must include identification of specific risk factors, and the monitoring of and interventions in the acute and subacute stages, and should aim at a pathophysiologically based approach to optimize the rehabilitative effort. Non-invasive optical techniques have been experimentally used in all three stages of the disease and may complement the established diagnostic and monitoring tools. Here, we provide an overview of studies using the methodology in the context of stroke, and we sketch perspectives of how they may be integrated into the assessment of the highly dynamic pathophysiological processes during the acute and subacute stages of the disease and also during rehabilitation and (secondary) prevention of stroke.     

Molecular intermediates in glow discharge polymerization

Mass spectral analysis of gaseous effluents from glow discharge polymerization of propylene confirms the formation of molecular propyne as an intermediate in the polymerization reaction. Observation of oligomeric species of mass number 138 or higher at the lowest monomer feed rate of the study indicates that a certain fraction of polymerization occurs in the gas phase.