Higher order perturbative QCD calculation of jet cross sections ine + e − annihilation

We present in detail the analytic calculation of the Sterman-Weinberg type 3-jet cross section to order α _s ² The fit to recent PLUTO data gives in the \({MS}\) scheme α _s which corresponds to Λ=0.24 GeV in the 1-loop approximation.     

Oxidation stability of crosslinked polyethylene. Isothermal DTA method

Isothermal differential thermal analysis has been used to study the thermooxidative stability of two grades of crosslinked polyethylene in the temperature range from 120°C to 230°C. Induction times of thermooxidative degradation were measured from 2 minutes up to 3590 hours. Oxidation Induction time and mechanical failure in oven ageing experiments coincided over the measured temperature range. The degree of crosslinking was not strongly affected by the oxidative reaction. The Arrhenius-plots of DTA results showed curvature at 150°C, so straight line extrapolations from short-term experiments at elevated temperatures to low temperatures and long times are not possible. Thermoanalytically measured residual thermooxidative stability decreased linearly with ageing time and showed great scattering of the results.

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Zusammenfassung Die isotherme Differentialthermoanalyse ist als Methode zur Abschätzung der thermooxidativen Beständigkeit von Polyolefinen seit längerem bekannt. In der vorliegenden Arbeit wird über isotherme DTA-Messungen an Proben aus vernetztem Polyäthylen im Temperaturbereich von 230°C bis 120°C berichtet, wobei Oxidationsinduktionszeiten bis zu 3590 Stunden gemessen wurden. Die Auftragung der Oxidationsinduktionszeiten in Arrhenius-Diagrammen zeigte für vernetztes Polyäthylen keine für Extrapolationszwecke geeignete Linearität des Logarithmus der Oxidationsinduktionszeiten über der reziproken absoluten Temperatur über weitere Bereiche der Meßzeiten bzw. Prüftemperaturen. Die thermoanalytisch bestimmten Oxidationsinduktionszeiten stimmten mit dem Steilabfall der Reißdehnung in Ofenalterungsversuchen überein während der über den Gelgehalt ermittelte Vernetzungsgrad vom thermooxidativen Abbau nicht signifikant beeinflußt wurde. Somit können aufwendige Ofenalterungsversuche durch experimentell einfache isotherme DTA-Versuche ersetzt werden. Die Messung der thermooxidativen Restbeständigkeit im isothermen DTA-Versuch bei erhöhter Prüftemperatur ermöglicht einen wesentlich deutlicheren Einblick in den thermooxidativen Schädigungszustand eines Polyolefins während der Induktionsperiode des thermooxidativen Abbaus als die Messungen des Vernetzungsgrades oder der Reißdehnung. Die Abnahme der thermooxidativen Restbeständigkeit erfolgt im Fall des vernetzten Polyäthylen in allen Fällen linear über der Alterungszeit.

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120–230°. 2 3590 . . . 150°, . .

     

Soliton concept in general relativity

Soliton physics has made considerable progress in solving nonlinear problems. This paper is meant to relate the soliten concept to the stationary axisymmetric vacuum fields in general relativity. We present a functional transformation which, working as a nonlinear creation operator, generates gravitational fields of isolated sources. When applied to flat space-time (gravitational vacuum) this operation leads to a nonlinear superposition of an arbitrary number of Kerr particles. This superposition also includes the Tomimatsu-Sato fields. The functional transformations form an infinite-parameter group which contains the Kinnersley-Geroch group as a subgroup.This essay received the second award from the Gravity Research Foundation for the year 1980.-Ed.     

Heterocyclische und carbocyclische 12-π- and 14-π-Molekülsysteme, 47. Mitteilung. Herstellung von 7, 9-Dimethyl-4, 5-dihydro-3 H-benz [cd]- azulen-3-on and 7,9-Dimethyl-3H-benz [cd]azulen-3-on. Eine einfache Synthese eines Azulenopseudophenalenons

Heterocyclic and Carbocyclic 12-π-and 14-π-Systems, 47th Commnunication¹. Synthesis of 7,9-Dimethyl-4,5-dihydro-3H-benz[cd]azualene-3-one and 7,9-Dimethyl-3H-benz[cd]azulene-3-one. A Simple Synthesis of Azulenopseudophenalenons 4, 6, 8-Trimethylazulene ( 3 ) reacts after metalation with lithiumdiisopropyl-amide in ether with bromoacetic acid to the 6, 8-dimethylaltulene-4-propionic acid ( 4 ), which undergoes cyclization to the 7, 9-dimethyl-4, 5-dihydro-3H-benz [cd]-azulene-3-one ( 5 ) in the presence of p-toluenesulfonic acid; oxidation of 5 with 2, 3-dichloro-5, 6-dicyanobenzoquinone yields 7, 9-dimethyl-3H-benz [cd]azulene-3--one ( 1b ). Alkylation of 1b with triethyloxonium tetrafluoroborate in CH₂C1₂ gives the 3-ethoxy [cd]benzazulenium tetrafluoroborate ( 6 ).     

Four-jet production in e+e−-annihilation

We investigate the four-jet production processes $e^{+}{e}^{?}\to q\overline{q}ggand{e}^{+}{e}^{?}\to q\overline{q}q\overline{q}$ in lowest order QCD perturbation theory. We estimate that four-jet events should be detectable at a rate of about 5% at the highest PETRA energy. The acoplanarity distribution is calculated and compared to nonperturbative effects.     

Convergence of m-bonacci ‘golden ratios’

This paper proves that the ratios of consecutive terms of the m-bonacci sequence converge to a limit φ_m < 2 and, as m → ∞, these φ_m converge to 2. Further, it is shown that the generating functions for the m-bonacci sequences converge pointwise to the geometric series.     

Alkali metal and ammonium cation–arene interactions with tetraphenylborate anion

Sodium, potassium, rubidium, caesium, ammonium and tetramethylammonium tetraphenylborates were studied by both positive and negative ion electrospray mass spectrometry. An affinity order of Cs⁺ > Rb⁺ > K⁺ ～ Na⁺ was obtained. The results obtained were compared with both calculations and solid-state structures, where available. The previously reported high affinity of caesium for tetraphenylborate concluded from NMR experiments was confirmed for the gas phase. The affinity does not appear to result from steric effects and a cation–pi interaction seems likely. In the positive ion mode, a unique acetonitrile complex of NaBPh₄ was observed.