1,981 research outputs found
Molecular twist transition in chiral and racemic phospholipid monolayers detected by Maxwell-displacement-current measurements
The molecular basis for the little (lit) mouse phenotype, characterized by a hypoplastic anterior pituitary gland, is the mutation of a single nucleotide that alters Asp 60 to Gly in the growth hormone releasing factor receptor. Detailed analysis of the lit mouse anterior pituitary reveals spatially distinct proliferative zones of growth hormone-producing stem cells and mature somatotrophs, each regulated by a different trophic factor. This sequential growth factor requirement for a specific cell type may exemplify a common strategy for regulating cellular proliferation in other mammalian organs
Towards the conversion of carbohydrate biomass feedstocks to biofuels via hydroxylmethylfurfural
This review appraises the chemical conversion processes recently reported for the production of
hydroxylmethylfurfural (HMF), a key biorefining intermediate, from carbohydrate biomass
feedstocks. Catalytic sites or groups required for the efficient and selective conversion of hexose
substrates to HMF are examined. The principle of concerted catalysis was used to rationalise the
dehydration of fructose and glucose to HMF in non-aqueous media. A survey of reported reaction
routes to diesel-range biofuel intermediates from HMF or furfural is presented and self-condensation
reaction routes for linking two or more HMF and furfural units together toward obtaining kerosene and diesel-range biofuel intermediates are highlighted. The reaction routes include: benzoin condensation, condensation of furfuryl alcohols, hetero Diels–Alder reaction and ketonisation
reaction. These reaction routes are yet to be exploited despite their potential for obtaining kerosene and diesel-range biofuel intermediates exclusively from furfural or hydroxylmethylfurfural
Thermal Evolution and Light Curves of Young Bare Strange Stars
The cooling of a young bare strange star is studied numerically by solving
the equations of energy conservation and heat transport for both normal and
superconducting strange quark matter inside the star. We show that the thermal
luminosity from the strange star surface, due to both photon emission and e+e-
pair production, may be orders of magnitude higher than the Eddington limit,
for about one day for normal quark matter but possibly for up to a hundred
years for superconducting quark matter, while the maximum of the photon
spectrum is in hard X-rays with a mean energy of ~ 100 keV or even more. This
differs both qualitatively and quantitatively from the photon emission from
young neutron stars and provides a definite observational signature for bare
strange stars. It is shown that the energy gap of superconducting strange quark
matter may be estimated from the light curves if it is in the range from ~ 0.5
MeV to a few MeV.Comment: Ref [10] added and abstract shortened. 4 pages, 3 figures, revtex4.
To be published in Phys. Rev. Letter
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