Emitter velocity and anisotropy for quasi-molecular radiation in I-Au collisions

The velocity of the quasimolecular x-ray emitter is found via Doppler shift measurements. It is in agreement with the center of mass velocity. Applying Doppler shift corrections the intrinsic anisotropy of the quasi-molecularM radiation is determined as a function of x-ray energy for 6 to 45 MeV I bombardment on thin Au targets. Position and amplitude of the maximum anisotropy in the x-ray spectrum depend on impact energy.     

Recombination of U 92 + ions with electrons

Recombination of fully stripped U⁹²⁺ ions with electrons has been investigated at the Experimental Storage Ring (ESR) in Darmstadt. Absolute recombination rate coefficients have been measured for relative energies from 0 to 33 eV. For energies greater than 20 meV the experimental result is well described by the theory for radiative recombination (RR). Below 20 meV the experimental rate increasingly exceeds the RR calculation as observed previously in the recombination of light bare ions as well as of Bi⁸³⁺. This low-energy rate enhancement is shown to scale as Z^2.6 for bare ions, where Z is the atomic number of the ion. The U⁹²⁺ recombination rate enhancement is insensitive to changes of the electron density. Variation of the magnetic guiding field strength from 80 mT to 120 mT resulted in oscillations of the recombination rate at 0 eV. The oscillations are partly attributed to changes of the transverse electron temperature accompanying the change of the magnetic guiding field strength; partly they may be caused by uncompensated small changes of the interaction angle between the two beams. Received 1st March 2001 and Received in final form 20 April 2001     

Both systemic and local application of Granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy

Background  

The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.     

Measurements ofK-shell ionization with132Xe and208Pb projectiles in the energy range of 1.4–5.9 MeV/u

Projectile and targetK-shell ionization cross sections induced by 3.6-, 4.7-, and 5.9 MeV/u¹³²Xe ions and 1.4-, 3.6-, 4.7-, and 5.9 MeV/u²⁰⁸Pb ions from the UNILAC in thin solid targets between C and U are measured. The cross sections are discussed in terms of the molecular model of innershell vacancy production in heavy ion-atom collisions. The sharing of 2p _1/2σ vacancies between theK shells of the two collision partners in these very heavy ion-atom collisions is found to deviate from the Meyerhof-Demkov formula forR≦10^?2. The measured ionization cross sections are compared with theoretical calculations for 1sσ and 2p _1/2σ excitation cross sections. AZ _UA=Z₁+Z ₂ dependence is found independent ofZ ₁/Z ₂. Outer-shell vacancy configurations measured in these close encounters are reported.     

K-vacancy production by 3.6-, 4.75-, and 5.9-MeV/amu238U Ions

Projectile (Z ₁) and target (Z ₂)K-vacancy production cross sections induced by 3.6-, 4.75-, and 5.9-MeV/amu²³⁸U ions in selected targets between C and U are reported. The cross sections are discussed within the context of the molecular model of inner-shell vacancy production in heavy-ion-atom collisions. The measured 1sσ and 2pσ excitation cross sections are compared with semiempirical formulas, and with the perturbed-stationary-states calculations of Betz et al. The dependence of these cross sections onZ _u =Z₁+Z ₂ agrees well with the Betz calculations. However, the measured cross sections are factors of 2 to 4 (1sσ) and 4 to 5 (2pσ) larger than the theoretical values.     

Charge transfer in 1.4 MeV/u Ni q+→Kr collisions,q=16−22

Cross sections for the electron transfer from neutral Kr atoms to highly charged Ni ^q+ projectiles were measured at 1.4 MeV/u. Estimates on the contributions of single and double capture into the Ni-L shell and into excited states are extracted from measured cross sections for the Ni-L x-ray emission for incoming projectileL vacancies (q≧19). The role of metastable states produced in the capture process is analysed. We find that most of the capture directly populates the Ni-L shell, and the capture into excited states seems to be dominated by two-electron capture. The electrons involved in double transfer processes seem to be strongly correlated. An increase in the low-probability non-correlated double transfer with increasing number of incomingL-vacancies is indicated by the data.     

The x-ray spectrum of H-like uranium

By decelerating highly-charged, very heavy ions to low energies in the storage and cooler ring, ESR, a new brilliant source for projectile x-rays has been obtained. In a first precision spectroscopy experiment up to 2·10⁷ stored bare U⁹²⁺ ions have been decelerated down to 49 MeV/u before detecting the characteristic projectile x-rays associated with one-electron capture at the ESR gas target. The Lyman, Balmer and Paschen series are distinctly observed for hydrogenic U⁹¹⁺ ions.     

Bioconversion of a L-carnitin precursor in a one- or two-phase system

Applied Biochemistry and Biotechnology - The ability of the yeastSaccharomyces cerevisiae to bioconvert stereo-selectively octyl-4-chloroacetoacetate (OCA) into the corresponding chiral alcohol,...