146 research outputs found
Subthreshold K+ production in deuteron and alpha induced nuclear reactions
Double differential cross sections have been measured for pi+ and K+ emitted
around midraidity in d+A and He+A collisions at a beam kinetic energy of 1.15
GeV/nucleon. The total pi+ yield increases by a factor of about 2 when using an
alpha projectile instead of a deuteron whereas the K+ yield increases by a
factor of about 4. According to transport calculations, the K+ enhancement
depends both on the number of hadron-hadron collisions and on the energy
available in those collisions: their center-of-mass energy increases with
increasing number of projectile nucleons
Obtención de shortenings cero-trans con alta estabilidad termo-oxidativa por transesterificación enzimática
Novel zero-trans frying shortenings were formed by enzymatic transesterification by exploring a palm stearin and canola oil mixture and stearic acid as substrates. Both immobilized (Novozym 435, Lipase PS “Amano” IM) and non-immobilized (Lipomod TM 34P) enzymes were applied as biocatalysts. Palmitic acid, the fatty acid which defines the proper type of crystal formation, was present at the 15% level in the reaction mixtures. The novel structured lipids had comparable physical properties and offered similar frying performance to those of commercial shortening. Needle-shaped crystals were predominant both in the transesterification products and the commercial frying shortening. Furthermore, solid fat content profiles of the zero-trans structured lipids produced by Novozym 435 and Lipase PS “Amano” IM were close to those of the commercial shortening.Los innovadores shortenings cero-trans para frituras se obtenían por transesterificación enzimática utilizando como sustratos una mezcla de estearina de palma con aceite de cánola y ácido esteárico. Tanto las enzimas inmovilizadas (Novozym 435, Lipase PS “Amano” IM) como las no inmovilizadas (Lipomod TM 34P) fueron aplicadas como biocatalizadores. El contenido de ácido palmítico, el ácido graso que define el tipo adecuado de formación cristalina, fue del 15% en las mezclas de reacción. Los lípidos estructurados innovadores tenían propiedades físicas comparables a los shortenings comerciales y estabilidad de oxidación térmica similar en proceso de fritura. Los cristales en forma de aguja predominaban tanto en los productos de transesterificación como en los shortenings para frituras disponible en el mercado. Además, los perfiles de contenido de grasa sólida de los lípidos estructurados cero trans producidos por Novozym 435 y Lipase PS “Amano” IM eran similares a los perfiles de los shortenings comerciales
Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy Ion Collisions
The production of pions and kaons has been measured in Au+Au collisions at
beam energies from 0.6 to 1.5 AGeV with the Kaon Spectrometer at SIS/GSI. The
K+ meson multiplicity per nucleon is enhanced in Au+Au collisions by factors up
to 6 relative to C+C reactions whereas the corresponding pion ratio is reduced.
The ratio of the K+ meson excitation functions for Au+Au and C+C collisions
increases with decreasing beam energy. This behavior is expected for a soft
nuclear equation-of-state.Comment: 14 pages, 2 figures, accepted for publication in Phys. Rev. Let
Kaon and Antikaon Production in Heavy Ion Collisions at 1.5 AGeV
At the Kaon Spectrometer KaoS at SIS, GSI the production of kaons and
antikaons in heavy ion reactions at a beam energy of 1.5 AGeV has been measured
for the collision systems Ni+Ni and Au+Au. The K-/K+ ratio is found to be
constant for both systems and as a function of impact parameter but the slopes
of K+ and K- spectra differ for all impact parameters. Furthermore the
respective polar angle distributions will be presented as a function of
centrality.Comment: 4 pages, 4 figures, SQM2001 in Frankfurt, Sept.2001, submitted to
Journal of Physics
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