Isolation of22Na for intense positron sources

A method of removing²²Na from Al via distillation is investigated. Distillation is rapid (≈10 minutes) and nearly quantitative. When the distilled vapor is directed by a flow of He gas the deposit may be localized fairly well and easily recovered with water.     

Adsorption von inerten Gasen an NaCl. I. Bestimmung der Verteilungen der adsorptiven Energie nach einer neuen numerischen Methode

Ohne Zusammenfassung     

Search for a parity-violating energy difference between enantiomers of a chiral iron complex

Mossbauer spectra for l and d enantiomers of the Fe(phen)3Sb2(C4H2O6)(2);8H(2)O complex are reported. Four independent experiments show a small but reproducible energy shift of the Fe-Mossbauer spectra for the two enantiomers of 0.004+/-0. 002 mm/sec ( 1.9x10(-10) eV). This exceedingly small energy difference is comparable to that predicted by the parity-violating energy difference (PVED) using a Z6.2 scaling law applied to low Z ( Z = 6) molecules. Theoretical calculations suggest that the PVED for the Fe(phen)2+3 moiety should be smaller than this estimate, however, PVED effects of the chiral antimony tartrates are not taken into account.     

Catalyst control in sequential asymmetric allylic substitution: stereodivergent access to N,N-diprotected unnatural amino acids

The sequential use of Cu-catalyzed asymmetric allylic alkylation, olefin cross-metathesis, and Ir-catalyzed asymmetric allylic amination allows the concise, stereodivergent synthesis of complex chiral amines with complete regiocontrol and good diastereoselectivity, exemplified by the synthesis of a pair of diastereoisomeric unnatural branched amino acid derivatives.     

Ensemble Effects on Methanol Oxidation to Formaldehyde on Ferric Molybdate Catalysts

The properties of Mo-doped iron oxide are compared with those of the single oxides of Fe and Mo, and with stoichiometric ferric molybdate for the selective oxidation of methanol. It is found that Mo oxide segregates to the surface of the iron oxide at low loadings, while at higher loadings, but below the stoichiometric ratio, presents layers of ferric molybdate at the surface. The relationship between bulk loading and surface Mo is explored, and it is concluded that the reactivity is dominated by ensemble effects. Simple modelling indicates that four or more Fe cation ensembles are required to combust methanol to CO₂, ensembles of two Mo cations are required for selective oxidation to formaldehyde, whereas it seems that isolated single sites of either Fe or Mo produce CO.