Ueber Titriren des Zinks mittels Schwefelnatriums

Ohne Zusammenfassung     

Electric polarization generated by the solid-state polymerization of pTS

Single crystals of pTS (bis-p-toluene sulphonate of 2,4-hexadiyne-1,6-diol), when annealed at 350 K, generate an electrical signal peaking at a time corresponding to that of a maximum polymerization rate. It is shown that a steady-state polarization of the order of 10^?4 C/m² is built into the pTS samples during the polymerization. The effect is probably associated with a non-compensated dipolar species created on polymerizing pTS crystals, and possibly also accounts for the pyroelectricity of poly-pTS.     

Template chromatography on immobilized oligonucleotides. Synthesis and application of oligodeoxyadenosine-5'-phosphate--DEAE-cellulose (author's transl)]

Oligomers of deoxyadenylic acid, obtained by polycondensation, were covalently attached to polyvinyl alcohol. These polymer-bound oligonucleotides undergo very strong adsorption on DEAE-cellulose such that at neutral pH and with 1 M NaCl, partial desorbtion occurs only above 60 degrees. The use of this PV(pA)n-DEAE-cellulose for the column chromatographic separation of deoxythymidylic acid oligomers obtained by polycondensation, according to the principle of base-pairing, is discussed. Linear oligomers and also pyrophosphate derivatives of thymidylic acid which contain more than five monomer units undergo strong retardation under the conditions of base-pairing. Cyclic oligonucleotides do not show any noticeable interaction with the stationary phase. Thus, through the use of a temperature gradient, it is possible to fractionally separate the polycondensate, giving an average degree of polymerisation of 6--10.     

Zur komplexometrischen Titration von Wismut

Zusammenfassung Bei der komplexometrischen Titration von Bi³⁺ mit ÄDTA gegen den Indicator Brenzcatechinviolett wurden Abweichungen vom theoretischen Wert festgestellt, wenn der p_H-Wert der Probelösung mit 1 n Natronlauge Pyridin oder verd. Ammoniak eingestellt worden war. Die resultierenden negativen Abweichungen lassen sich durch die Bildung von Polykationen erklären.Die Größe des Titrationsfehlers wächst mit steigender Basizität und größerem Verteilungsgrad der zugesetzten Reagentien; sie verringert sich bei steigender Acidität der Probelösung. — Einmal gebildete Polykationen lassen sich durch Zugabe von Säure nicht sofort wieder auflösen.p_H-Einstellungen mit 1 m NaHCO₃- und 1 m NaCH₃COO-Lösungen lieferten dagegen keine Fehltitrationen.Alle untersuchten Indicatoren ergaben unter konstanten Bedingungen gleiche Titrationsfehler.Herrn Prof. Dr. O. Glemser danken wir für sein förderndes Interesse. Der Deutschen Forschungsgemeinschaft gilt unser Dank für die uns zur Verfügung gestellten Hilfsmittel.     

Systematic analysis of the PSI experiment to directly measure the sticking probabilityω s in dt fusion

Starting in 1989 an experiment was run at PSI to directly measure the final sticking probability in muon catalyzed dt fusion. This experiment was based on an active-target ionization chamber (IC) built at Gatchina, Russia, and an array of plastic neutron counters. In three runs approximately 5×10⁶ isolated alpha signals were recorded with around one half of these occurring in the inner chamber region where we have more complete understanding of the systematic errors. Particularly from a long run in 1992 we were able to obtain a very clean sticking peak of some 5000 events. However, to reach an accurate value of sticking, all systematic effects and several major backgrounds had to be understood in detail. To this end a Monte Carlo code was written to simulate the full electrostatic environment of the IC and to recreate completely each signal type including the actual tritium decay noise from the live experiment. A slightly model dependent value of approx. 0.56±0.04% is obtained for final sticking.     

Feasibility of an experiment to determine the branching ratio for the emission of a heavy neutrino after muon capture in3He

The triton energy of the muon capture reaction ³He t+v, where ³ He is the ground state of muonic³He, has been measured in order to investigate a possible heavy v admixture into the flavour with high sensitivity. ³ He has been formed via the pd fusion reaction by stopping ^– in an ionization chamber (IC) filled with an H/D gas mixture of 3% D concentration at a pressure of 161 bar. In a first short experiment 650 triton events were observed yielding an upper limit for the -heavy v mixing strength of 2.3×10^–3 atE _0v=60 MeV.     

Survey of experimental results on μCF including hyperfine effects

Complementary to the investigations of the most efficient dt cycle, also the other muon-induced fusion cycles in mixtures of hydrogen isotopes have been studied. The results of these dedicated experiments provide rich information about muon-induced few-body reactions and contribute significantly to a better overall understanding of CF. A summary of the recent progress will be presented. Special emphasis will be put on two characteristic examples, namely a new experimental approach to study the muonic cascade in H-D mixtures and the systematic study of hyperfine effects in muon-induced reactions.     

The kinetics of muon-catalyzed dt fusion

A main source of information about the muon-catalyzed fusion cycle in D-T mixtures are the cycling rates _c, which are characteristic for the kinetic equilibrium of states attained rapidly in dense targets. The measurement, analysis and interpretation of these rates will be discussed, concentrating on the extensive set of rates observed at PSI over the last decade in gaseous, liquid and solid targets.Invited talk presented by Peter Kammel.