The electrochemistry of square planar macrocyclic nickel complexes and the reaction of Ni(I) with alkyl bromides: Nickel tetraamine complexes

The electrochemistry of nine cyclic tetraamine complexes of Ni(II) in aprotic solvents has been investigated. It is shown that all form Ni(I) complexes which react with alkyl bromides, but only with some complexes are the reactions catalytic with respect to the nickel complex. The dependence of the electrochemical parameters and the mechanism and kinetics of the coupled chemical reactions on the structure of the ligands are discussed.     

Stellar reaction rate of 20Ne(α, γ)24Mg

The reaction ²⁰Ne(α, γ)²⁴Mg has been investigated at E_α(lab) = 0.55–3.20 MeV. Neon gas enriched to 99.95% in ²⁰Ne was recirculated in differentially pumped gas target systems of the extended and quasipoint jet types. New resonances were found at E_α(lab) = 958, 1226, 1260, 1704 and 2277 keV, which correspond to known states in ²⁴Mg. Excitation energies, γ-ray decay schemes, γ-ray angular distributions, resonance widths and strengths as well as J^π and T-assignments are reported for all the resonances. Information on low-lying states in ²⁴Mg is also obtained. The nuclear and astrophysical aspects of the results are discussed.     

Resonance strengths of some light nuclei

The strengths of theE _c.m.=324 and 829 keV resonances in¹⁹F(ρ, αγ)¹⁶O have been determined relative to the Rutherford elastic scattering cross section. With these values as standards, the strengths of theE _c.m.=259, {pp143} (also 1,106) and 1,259 keV resonances in¹⁴N(ρ, γ)¹⁵ O,¹⁸O(ρp, γy)¹⁹F and¹⁴N(α, γ)¹⁸F were measured, respectively. In addition, the cross section of the direct capture process in¹⁶O(ρ, γ)¹⁷F atE _c.m.=853 keV has been obtained. All measurements were carried out by interchanging the role of projectiles and target nuclei, i.e.¹⁴N,¹⁶O,¹⁸O and¹⁹F ion beams of appropriate energies were guided into windowless gas target systems filled with hydrogen or helium gas. The results are compared with previous work.     

Bestimmung der Serumkonzentration von Methotrexat mit einem S?ulenschaltverfahren

Zusammenfassung Neben einer vollständigen Retention von MTX an einer Vorsäule konnte eine gute Trennung von seinen Metaboliten und von Verunreinigungen auf einer Reversed-phase-Säule erzielt werden. 0,1 bis 2000 mol/l können bestimmt werden. Die Wiederfindung beträgt über den gesamten Konzentrationsbereich 100%. Die Präzision beträgt 2,3–4,8% in der Serie und 3,5–5,4 % zwischen den Tagen.

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Determination of methotrexate in serum by a back-flush HPLC method

Summary Besides a complete retention of MTX on the precolumn, a good separation of the compound from its metabolites and contaminations can be achieved on a reversedphase column. 0.1 to 2,000 mol/l may be determined. The recovery is 100% over the whole concentration range. The precision is 2.3–4.8% in the series and 3.5–5.4% between the days.

     

Une structure uniforme faible remarquable,sur les cones faiblement complets

Sans résumé     

Observation of superdeformed bands in194Hg

Two rotational bands, with energy spacings characteristic of superdeformed shapes, have been observed following bombardment of¹⁵⁰Nd with⁴⁸Ca. The more intensively populated band consists of 18 transitions and is assigned to¹⁹⁴Hg. The depopulation of this band occurs around spin 10. The second band, consisting of at least 16 transitions, was populated less strongly and is tentatively assigned to¹⁹⁴Hg also. The lowest level in this band is assigned spin 8. The energy differences between transitions for both bands decrease from ～40 keV at low rotational frequencies to ～30 keV at the highest observed frequencies. The moments of inertia of the bands are similar to those of the two previously observed superdeformed bands in^191,192Hg. The similarities and differences of the four known bands in the mercury region are discussed.