Measurements of the diffusion parameters in diphenyl at temperatures from 20 °C to 170 °C

Diffusion coefficient, mean life time of thermal neutrons, coefficient of diffusion cooling and diffusion length in diphenyl at temperatures 20°, 40°, 60°, 80°, 110°, 140° and 170° C were measured by the pulse method. Their dependence on the temperature of diphenyl was deduced in an analytic form and the change of the neutron transport length was determined experimentally. No discontinuity of the diffusion coefficient at the melting point of diphenyl apart from that caused by density change was observed. The energy exchange cross sectionM ₂ is practically independent of temperature in the range from 20 °C to 170 °C and the deduced microscopic absorption cross section for hydrogen equals 337±2 millibarns. The thermalization of neutrons in diphenyl proceeds more slowly than in water and neutrons loose their energy predominantly by interaction with the C—H group of the diphenyl molecule.We are indebted to Mr. J.Jadavan and Mr. J.Jirou for their technical assistance during the measurements and setting up the measuring apparatus.     

Blutzucker

Ohne Zusammenfassung     

Identifizierung von Sulfiden

Ohne Zusammenfassung     

Discriminantal Arrangements, Fiber Polytopes and Formality

Manin and Schechtman defined the discriminantal arrangement of a generic hyperplane arrangement as a generalization of the braid arrangement. This paper shows their construction is dual to the fiber zonotope construction of Billera and Sturmfels, and thus makes sense even when the base arrangement is not generic. The hyperplanes, face lattices and intersection lattices of discriminantal arrangements are studied. The discriminantal arrangement over a generic arrangement is shown to be formal (and in some cases 3–formal), though it is in general not free. An example of a free discriminantal arrangement over a generic arrangement is given.     

Cellulase Ss (CelS) is synonymous with the major cellobiohydrolase (subunit S8) from the cellulosome ofClostridium thermocellum

The controversy regarding the identity of a major cellulosomal component type from two different strains ofClostridium thermocellum has been resolved. The principal cellobiohydrolase, subunit S8, from the cellulosome of strain YS has been demonstrated to be synonymous with cellulase component S_s (CelS) from the cellulosome of ATCC strain 27405. This component is not related to any other cellulosomal subunit or cloned endoglucanase in this organism.     

Quantum dot multiexcitons in a magnetic field

Multiexcitons confined in InGaAs/GaAs quantum dots (QDs) with a lateral size slightly exceeding the exciton Bohr radius are investigated by magnetophotoluminescence spectroscopy at 2 K. The Coulomb correlations in the two-exciton complex result in an additional confinement, which increases with decreasing dot size, while a magnetic field reduces this effect. A three-exciton complex is confined only by the geometric confinement potential of the QD. The exciton-exciton repulsion increases with decreasing dot size, while a magnetic field decreases the repulsion strongly when the magnetic length becomes smaller than the lateral size of the QD. A shell model for the QD multiexciton states is proposed. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 263–268 (25 August 1997) Published in English in the original Russian journal. Edited by Steve Torstveit.