The reaction238U +238U at 7.42MeV/u

One-particle-inclusive measurements have been performed for the charge, kinetic energy and angular distributions of reaction products from²³⁸U +²³⁸U at 1 766MeV (7.42MeV/u) incident energy. The deep inelastic products exhibit features similar to those seen in reactions induced by medium heavy nuclei: increasing particle transfer is observed with increasing energy damping, the angular distributions are peaked near the grazing angle, they broaden significantly with increasing energy loss and/or charge transfer. The dominant reaction mechanism, however, is found to be sequential fission of one or both primary reaction products. The reconstructed primaryZ- andQ-value distributions show more particle transfer at a given energy loss than in other systems, i.e. the diffusion process seems to proceed colder in this system. This is confirmed by relatively large cross sections for surviving deep inelastic reaction products belowZ=92. A direct search forα-decay or fission of superheavy nuclei being produced in a deep inelastic reaction and being implanted in a surface barrier detector resulted in an upper cross section limit of 2 ×10^?32cm².     

Infrarotspektroskopische Methoden zur quantitativen Analyse von Gemischen der Alkohole ?thanol, Isopropanol und n-Propanol

Zusammenfassung Es wurden 2 Analysenverfahren beschrieben, die beim Dreistoffsystem Äthanol-Isopropanol-n-Propanol die Möglichkeiten der quantitativen Infrarotspektroskopie in der Analytik darlegen sollten. Bei dem ersten Verfahren wurde je eine Schlüsselbande für eine Komponente benutzt, beim zweiten mit mehreren Analysenbanden je Komponente gerechnet. Zur Auswertung der Gleichungssysteme wurde die Determinantenrechnung angewandt.

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Summary Quantitative infrared spectroscopy has been applied to the ternary system ethanol-isopropanol-n-propanol and two analytical procedures have been described. In the first method one key band has been used for each component, in the second one several bands have been employed per component. Evaluation of the equation systems has been done by determinants.

     

Lower Rim Substituted tert-Butyl calix[4]arenes (I). The Structure and Complexing Properties in Ion-Selective PVC Membrane Electrodes

Some di- and tetraamide tert-butylcalix[4]areneswere synthesized and described. Their ionophoric properties were studied in liquid membrane ion-selective electrodes. The correlation between thechemical structure (conformation in solution determined by ¹H NMR) and potentiometric ion-selectivity and complex formation constant havebeen studied. The PVC membrane electrodes based on tetraamides 8–11 show high sodium selectivity, are stable and long lasting. Disubstituted amides 1–7 are selective for larger and more lipophilic ions, as for exampleguanidinium ion. The crystal structure of the diamide 4 was determined by single crystal X-ray analysis. Crystals of 4 are triclinic, spacegroup P-1, with: a = 16,669(8), b = 17.795(10), c = 20.984(8) Å, =91.08(4)°, = 91.60(3)°, = 90.73(4)° and Z = 4. Ionophore 4 posseses a distorted cone conformation and is substituted at the proximal phenol rings.     

Two-photon sensitive photolabile protecting groups: From molecular engineering to nanostructuration

ABSTRACT

General molecular engineering rules for the optimization of two-photon sensitive cages are presented and examples for nitrobenzyl, indole and nitrophenethyl platforms are highlighted. The efficiency of electron donor and acceptor groups in dipolar structures and the length of the conjugated system in the photolabile protecting group on two-photon uncaging efficiency will be discussed, as well as the emergence of symmetrical platform based on bis-electron donor or on quadrupolar architectures. We will then present our first results on the nano-structuration of donor-acceptor systems based on nitrophenetyl platform using diethyleneglycol or pentaerythritol cores.