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The total synthesis of the 3S,2S and 3R,2S diastereomers (1a and 1b) of minalemine A and the identification of the natural compound as the 3R,2S isomer is described. The key step in the synthesis is the preparation of the two enantiomers of the beta-amino diacid 3-(N-carboxymethyl)-aminodecanoic acid (Ncma), which were obtained by stereoselective alkylation(More)
The evolution of low molecular weight polyphenols in Spanish oak heartwood of Quercus robur,Quercus petraea, Quercus pyrenaica, and Quercus faginea was studied by HPLC, in relation to the processing of wood in barrel cooperage. The polyphenolic composition of Spanish woods subjected to natural seasoning for 3 years and to the toasting process was studied in(More)
The evolution of tannins in Spanish oak heartwood of Quercus robur L., Quercus petraea Liebl.,Quercus pyrenaica Wild., and Quercus faginea Lam. was studied in relation to the processing of wood in barrel cooperage. Their evolution was compared with that of French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus(More)
Many complex systems in nature and in human society exhibit time fluctuations characterized by a power spectrum S( f ) which is a power function of the frequency f . Examples with this behavior are the Sun spot activity, the human heartbeat, the DNA sequence, or Bach’s First Brandenburg Concert. In this work, we show that the energy spectrum fluctuations of(More)
Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a round-robin exercise where the participants measured and calculated specific saturation activities achievable for the 98Mo(n,γ)99Mo reaction. This reaction is of interest as a means to locally, and on a small scale,(More)
Three new pyridyltriazole ligands (named pyta) bearing a 4-substituted phenyl arm (nitro- (2a), chloro- (2b) or aminophenyl (2c) moiety) have been synthesized using a convenient click chemistry strategy. The corresponding tricarbonylrhenium complexes 3a, 3b and 3c were prepared and fully characterized by means of NMR, IR and mass spectrometry, as well as(More)
We develop a theory to calculate exciton binding energies of both twoand three-dimensional spin polarized exciton gases within a mean field approach. Our method allows the analysis of recent experiments showing the importance of the polarization and intensity of the excitation light on the exciton luminescence of GaAs quantum wells. We study the breaking of(More)
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