The decay of the neutron–rich nucleus 216Bi

The decay of the neutron–rich isotope ²¹⁶Bi, produced by proton–induced spallation at the PS Booster–ISOLDE facility, was investigated by β-γγ, αγ coincidence and spectrum-multiscaling measurements. A new method for reducing isobaric contamination enabled to cover the unknown region “east” of ²⁰⁸Pb for the isobaric chain A=216. The half-life of the β decay of ²¹⁶Bi was found as T_1/2= 135 ± 5 s. Its decay scheme was extended and the possible shell model configurations are proposed. Received: 13 July 1999 / Revised version: 22 September 1999     

Time- and temperature-dependent crosslinking behaviour of a silicone resin

The crosslinking behaviour of a silicone resin which is interesting from a technical point of view was investigated by means of rheology. In order to accelerate the crosslinking process, zinc acetylacetonate and aluminium acetylacetonate were applied as latent catalysts. The effect of the type of catalyst, its concentration, and the temperature on crosslinking was determined by isothermal dynamic-mechanical measurements. A radial gradient in crosslinking causes the gel point to be reached earlier at the outer edge of the sample in the rheometer. This radial gradient is averaged when measuring G′ and G″. Therefore, since the physically well-defined state of critical gelation (gel point) could not be obtained from the data, the time at which a distinct crosslinking state is reached was determined by the crossover of the moduli G′ and G″. For this distinguished point, the denotation gelation index GI is introduced. The gelation indices measured at different temperatures follow an Arrhenius-type relationship. Activation energies between 89 and 126 kJ/mol were determined. They were found to be dependent on the type of catalyst used but independent of its concentration. The activation energies of the crosslinking processes enable the calculation of the gelation index at temperatures not measured directly.     

Energy dependence of the total cross section for the reaction of 4He ions with silicon nuclei

Directly measured data on the total cross section for the reaction of projectile ⁴He ions with silicon nuclei at energies below 25 MeV/nucleon are presented. The energy dependence of the parameters of a semimicroscopic potential is determined from the measured values of this cross section. This investigation was performed at the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (Dubna, Russia) and at the Department of Physics at the University of Jyväskylä (Finland).     

Solid composite electrodes for DNA enrichment and detection

New plastic composite electrodes with appliance in medical diagnostic are described. The new electrode material offers the possibility of specific electrical enrichment and electrochemical analysis of nucleic acid sequences. To facilitate selective enrichment of target nucleic acids, specific probe oligonucleotides were attached covalently to free carboxyl groups of conducting polycarbonate/carbon fiber electrodes. Complementary oligonucleotides were enriched from analyte solutions by electric field supported methods. The analysis of the PCR product shows the efficiency and selectivity of the electrical enrichment. We have also shown that inexpensive and robust solid electrodes made of polycarbonate and conductive carbon powder are suitable for electrochemical examination of nucleic acids. The combination of electrochemical enrichment of DNA and subsequent electrochemical detection is a promising approach towards an inexpensive molecular diagnosis kit.     

Simultaneous three-dimensional gas-liquid chromatography on wall-coated glass-capillary columns

Summary A new system for multiple simultaneous gas-liquid chromatographic analysis is described. A commercially available gas chromatograph was modified to accommodate three wall-coated glass-capillary columns. A novel design of both the injection port and sample splitter allows the admission of equal portions of the sample into each of the three columns from a single injection. This provides the analyst either with data for the sample in question on three different liquid phases, or with a single result in triplicate if the same liquid phase is used on all columns. This presentation briefly describes the geometry of the inlet system; details will be published shortly. The performance of this system is illustrated with a simple example. In an artificial mixture, the quantitative GLC-data of 6 compounds obtained on three different columns were unequivocally correlated. A correlation number (CN) is derived which gives the maximum possible number of compounds that can be theoretically correlated in a mixture by the system described.     

Neutron emission from Bi+Pb collisions at 1 GeV/u

The experimental study of the neutron emission from Bi+Pb collisions at 1 GeV/u was done using BaF₂ detector. The heavy-ion collision dynamics was investigated through genuine collective phenomena: nuclear flow effects and production of neutrons near and beyond free NN kinematical limit.Presented at the International School-Workshop Relativistic Heavy-Ion Physics, Prague (Czech Republic), 19–23 September 1994.     

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Interferometry of direct photons in central 208Pb + 208Pb collisions at 158A GeV

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100相似文献