Die Wärmeausdehnung von technisch reinem Eisen (Armco-Eisen) und Reineisen zwischen −190 und 1450 °C

Kontinuierliche Aufnahme von Dilatomelerkurven von technisch reinem Eisen (Armco-Eisen) und Reineisen für den Temperaturbereich ?190 bis 1450 °C. Ermittlung des Kontraktions- uiul Dilationsverhaltens im Verlauf der α-γ- und γ-δ-Umwandlung und des integralen und differentiellen Ausdehnungskoeffizienten. Einfluβ einer Wärmebehandlung bei 1450 °C auf das Umwandlungsverhalten. Erörterung der Ergebnisse.     

Infinite cube-connected cycles

An infinite network for parallel computation is presented which can for every k become partitioned in cube-connected cycles-networks of size 2^2k2^k [1]. This construction extends a result from [2], where finite such networks are constructed. This infinite network is useful for simplifying the structure and improving the efficiency of the general purpose parallel computer shown in [3].     

Nitrogen Leaching from <Superscript>15</Superscript>N Labelled Cow Urine and Dung Applied to Grassland on a Sandy Soil

Nitrogen (N) leaching under grazed pastures can be very high directly under urine spots. The amount of N which is returned by one excretion of urine or dung can locally exceed 1000 kg ha⁻¹ a⁻¹ which is far more than the uptake by surrounding plants during one grazing period. We therefore quantified the contribution of N deriving from urine and dung to the total N leaching under urine and dung patches. Dung N and urine N was separately sampled from a cow feed with ¹⁵N labelled grassilage, and were amended on lysimeters in October 2000 and October 2001. Lysimeters (350 mm diameter and 800 mm length) were filled with sand, and an intact grass sod from a pasture, 4 lysimeter each were amended with the ¹⁵N labelled dung and urine; 4 lysimeters without an application of dung or urine served as control. During 11 months after dung and urine amendment the amount of leachate was monitored and leachate was analysed for nitrate, ammonium and total N. ¹⁵N in these fractions was measured. Dung and urine applications of 1052 and 1030 kg N ha⁻¹ in autumn increased N leaching. Leaching loss of nitrate and dissolved organic N deriving from dung was only 37 kg N ha⁻¹ in both years, whereas under urine patches 447 kg nitrate-N ha⁻¹, 108 kg N ha⁻¹ ammonia-N and 53 kg ha⁻¹ dissolved organic N leached on average of both experimental years. N not deriving from dung and urine exceeded the leached N under the control by about 36 and 136 kg ha⁻¹ on average of both years, suggesting the contribution of different priming processes.     

Optimierende reaktionsführung lebender polymerer. Darstellung von produkten mit bimodalen molekulargewichtsverteilungsfunktionen im rohrreaktor

Polymers with bimodal molecular weight distributions are remarkable for advantageous cold flow properties and good manufacturing. Using polyreaction of isoprene with n-butyllithium in n-heptane as an example for polyreactions of living polymers, for a tubular flow reactor with double initiator infusion a procedure is described which permits to precalculate optimal values of control variables used for the production of polymers which have required bimodal molecular weight distributions. The analysis of thus produced polymers by ultracentrifugal measurements shows an excellent agreement of theoretical and practical molecular weight distributions.