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Context.More and more evidence leads to considering classical Be stars as rotating close to the critical velocity. If so, then the question that arises is the origin of this high surface velocity.

Aims.We propose the Wind of Fast Rotating Massive Stars scenario to explain the origin of the abundance anomalies observed in globular clusters.

We investigate the effect of new stellar models taking rotation into account and computing for a metallicity $Z = 10^{-8}$on the chemical evolution of the earliest phases of the Milky Way. These models were computed under the assumption that the ratio of the initial rotation velocity to the critical velocity of stars is roughly constant with metallicity. This naturally leads to faster rotation at lower metallicity, as metal-poor stars are more compact than metal-rich ones. We find that the new $Z = 10^{-8}$stellar yields have a tremendous impact on the nitrogen enrichment of the interstellar medium for log(O/H) + 12 < 7 (or $\rm [Fe/H]< -3$). We show that including $Z = 10^{-8}$stellar yields in chemical evolution models, both high N/O and C/O ratios are obtained in the very-metal poor metallicity range, in agreement with observations. Our results give further support to the idea that stars at very low metallicities could have rotational velocities of the order of 600-800 km s-1.

Context.Aims.We examine the role of rotation on the evolution and chemical yields of very metal-poor stars. Methods.The models include the same physics, which was applied successfully at the solar Zand for the SMC, in particular, shear diffusion, meridional circulation, horizontal turbulence, and rotationally enhanced mass loss. Results.Models of very low Zexperience a much stronger internal mixing in all phases than at solar Z. Also, rotating models at very low Z, contrary to the usual considerations, show a large mass loss, which mainly results from the efficient mixing of the products of the 3αreaction into the H-burning shell. This mixing allows convective dredge-up to enrich the stellar surface in heavy elements during the red supergiant phase, which in turn favours a large loss of mass by stellar winds, especially as rotation also increases the duration of this phase. On the whole, the low Zstars may lose about half of their mass. Massive stars initially rotating at half of their critical velocity are likely to avoid the pair-instability supernova. The chemical composition of the rotationally enhanced winds of very low Zstars show large CNO enhancements by factors of 103to 107, together with large excesses of 13C and 17O and moderate amounts of Na and Al. The excesses of primary N are particularly striking. When these ejecta from the rotationally enhanced winds are diluted with the supernova ejecta from the corresponding CO cores, we find [C/Fe], [N/Fe], [O/Fe] abundance ratios that are very similar to those observed in the C-rich, extremely metal-poor stars (CEMP). We show that rotating AGB stars and rotating massive stars have about the same effects on the CNO enhancements. Abundances of s-process elements and the 12C/13C ratio could help us to distinguish between contributions from AGB and massive stars. Conclusions.

Although the theoretical study of very low metallicity (Z) and metal–free stars is not new, their importance has recently greatly increased since two related fields have been developing rapidly. The first is cosmological simulations of the formation of the first stars and of the reionisation period. The second is the observations of extremely metal poor stars. In this paper, we present pre–supernova evolution models of massive rotating stars at very low Z(Z= 10-8) and at Z= 0. Rotation has a strong impact on mass loss and nucleosynthesis. Models reaching break–up velocities lose up to ten percents of their initial mass. In very low Zmodels, rotational and convective mixing enhances significantly the surface content in carbon, nitrogen and oxygen (CNO) when the star becomes a red supergiant. This induces a strong mass loss for stars more massive than about 60 M๏. Our models predict type Ib,c supernovae and gamma–ray bursts at very low Z. Rotational mixing also induces a large production of CNO elements, in particular of primary nitrogen. The stellar wind chemical composition is compatible with the most metal–poor star know to date, HE 1327–2326, for CNO elements. Our models reproduce the early evolution of nitrogen in the Milky Way.

The inclusion of rotation in massive star models improves the agreement between theory and observations in many respects that are briefly recalled here. Rotational mixing, by changing the chemical profiles in the stellar interiors, has important impacts on nucleosynthesis. We shall first discuss the case of solar metallicity models and then explore consequences both in the high and very low metallicity ranges. The effects in very metal–poor stars are spectacular and give new insights on the evolution of the early star generations in the Universe.

With the human genome in a first sequence draft and several other genomes being finished this year, the existing information gap between genomics and proteomics is becoming increasingly evident. The analysis of the proteome is, however, much more complicated because the synthesis and structural requirements of functional proteins are different from the easily handled oligonucleotides, for which a first analytical breakthrough already has come in the use of DNA chips. In comparison with the DNA microarrays, the protein arrays, or protein chips, offer the distinct possibility of developing a rapid global analysis of the entire proteome. Thus, the concept of comparing proteomic maps of healthy and diseased cells may allow us to understand cell signaling and metabolic pathways and will form a novel base for pharmaceutical companies to develop future therapeutics much more rapidly. This report demonstrates the possibilities of designing protein chips based on specially constructed, small recombinant antibody fragments using nanostructure surfaces with biocompatible characteristics, resulting in sensitive detection in the 600-amol range. The assay readout allows the determination of single or multiple antigen-antibody interactions. Mass identity of the antigens, currently with a resolution of 8000, enables the detection of structural modifications of single proteins.

The use of porous silicon (PS) as an efficient surface enlarging carrier matrix for immobilised enzymes is demonstrated. An optimal porous matrix in p-type silicon (10–20 Ωcm) with respect to enzymatic substrate turn-over was obtained when anodising the sample at 100 mA/cm2 for 5 min. An increase in glucose turn-over of 220 times as compared to an enzyme activated polished surface was recorded. The highest increase in turn-over was found to be 350 times for an n-epilayer on n+ substrate. The application of glucose monitoring is demonstrated showing a linear range to 15 mM glucose with a satisfactory storage and operational stability. The use of ascorbate oxidase activated porous silicon for the elimination of ascorbate (an electrochemical interferent) in glutamate monitoring is reported. An upper elimination level of 1 mM ascorbate was found. PS is also reported as an efficient protein cleavage surface when activated with proteases. Cleavage times normally ranging between 6 and 24 h were found to be 60 s in the microreactor. Myoglobin cleaved on a trypsin microreactor is shown with the corresponding mass spectra having a sequence coverage of 79%.

Context.Since the external regions of the envelopes of rapidly rotating early-type stars are unstable to convection, a coupling may exist between the convection and the internal rotation.

Context.Light elements and nitrogen surface abundances together can constrain the mixing efficiencies in massive stars on the main sequence, because moderate mixing in the surface layers leads to depletion of light elements but only later to enrichment in nitrogen.

Context. The identification of long-gamma-ray-bursts (LGRBs) is still uncertain, although the collapsar engine of fast-rotating massive stars is gaining a strong consensus.Aims. We propose that low-metallicity Be and Oe stars, which are massive fast rotators, as potential LGRBs progenitors.Methods. We checked this hypothesis by 1) testing the global specific angular momentum of Oe/Be stars in the ZAMS with the SMC metallicity; 2) comparing the ZAMS (Ω/Ωc,M/$M_{\odot}$) parameters of these stars with the area predicted theoretically for progenitors with metallicity Z= 0.002; and 3) calculating the expected rate of LGRBs/year/galaxy and comparing them with the observed ones. To this end, we determined the ZAMS linear and angular rotational velocities for SMC Be and Oe stars using the observed Vsin iparameters, corrected from the underestimation induced by the gravitational darkening effect.Results. The angular velocities of SMC Oe/Be stars are on average $\langle$Ω/Ωc$\rangle$= 0.95 in the ZAMS. These velocities are in the area theoretically predicted for the LGRBs progenitors. We estimated the yearly rate per galaxy of LGRBs and the number of LGRBs produced in the local Universe up to z= 0.2. We have considered that the mass range of LGRB progenitors corresponds to stars hotter than spectral types B0-B1 and used individual beaming angles from 5 to 15°. We thus obtain R^{\rm pred}_{\rm LGRB}$~ 10-7to ~10-6LGRBs/year/galaxy, which represents on average 2 to 14 LGRB predicted events in the local Universe during the past 11 years. The predicted rates could widely surpass the observed ones [(0.2–3)×10-7LGRBs/year/galaxy; 8 LGRBs observed in the local Universe during the last 11 years] if the stellar counts were made from the spectral type B1-B2, in accordance with the expected apparent spectral types of the appropriate massive fast rotators.Conclusions. We conclude that the massive Be/Oe stars with SMC metallicity could be LGRBs progenitors. Nevertheless, other SMC O/B stars without emission lines, which have high enough specific angular momentum, can enhance the predicted RLGRBrate.

Context. The identification of long-gamma-ray-bursts (LGRBs) is still uncertain, although the collapsar engine of fast-rotating massive stars is gaining a strong consensus.

Aims. A variation of the fundamental constants is expected to affect the thermonuclear rates important for stellar nucleosynthesis. In particular, because of the very low resonant energies of 8Be and 12C, the triple αprocess is extremely sensitive to any such variations.

Aims. A variation of the fundamental constants is expected to affect the thermonuclear rates important for stellar nucleosynthesis. In particular, because of the very low resonant energies of 8Be and 12C, the triple αprocess is extremely sensitive to any such variations.Methods. Using a microscopic model for these nuclei, we derive the sensitivity of the Hoyle state to the nucleon-nucleon potential, thereby allowing for a change in the magnitude of the nuclear interaction. We follow the evolution of 15 and 60 $M_{\odot}$zero-metallicity stellar models, up to the end of core helium burning. These stars are assumed to be representative of the first, Population III stars.Results. We derive limits on the variation in the magnitude of the nuclear interaction and model dependent limits on the variation of the fine structure constant based on the calculated oxygen and carbon abundances resulting from helium burning. The requirement that some 12C and 16O be present at the end of the helium burning phase allows for permille limits on the change in the nuclear interaction and limits of the order of 10-5on the fine structure constant relevant at a cosmological redshift of z~ 15-20.