Uncertainty quantification of leakages in a multistage simulation and comparison with experiments

The present paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiency but the impact of the random variation of the clearance height has not been investigated before. In this paper the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested. By using a Non-Intrusive Uncertainty Quantification simulation based on a Sparse Arbitrary Moment Based Approach, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades. This work shows that the impact of gap uncertainties propagates radially from the tip towards the hub of the turbine and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low aspect ratio of the turbine and a similar behavior is expected in high pressure turbines

Use of the KlADH4 promoter for ethanol-dependent production of recombinant human serum albumine in Kluyveromyces lactis

KlADH4 is a gene of Kluyveromyces lactis encoding a mitochondrial alcohol dehydrogenase activity which is specifically induced by ethanol. The promoter of this gene was used for the expression of heterologous proteins in K. lactis, a very promising organism which can be used as an alternative host to Saccharomyces cerevisiae due to its good secretory properties. In this paper we report the ethanol-driven expression in K. lactis of the bacterial beta-glucuronidase and of the human serum albumin (HSA) genes under the control of the KlADH4 promoter. In particular, we studied the extracellular production of recombinant HSA (rHSA) with integrative and replicative vectors and obtained a significant increase in the amount of the protein with multicopy vectors, showing that no limitation of KlADH4 trans-acting factors occurred in the cells. By deletion analysis of the promoter, we identified an element (UASE) which is sufficient for the induction of KlADH4 by ethanol and, when inserted in the respective promoters, allows ethanol-dependent activation of other yeast genes, such as PGK and LAC4. We also analyzed the effect of medium composition on cell growth and protein secretion. A clear improvement in the production of the recombinant protein was achieved by shifting from batch cultures (0.3 g/liter) to fed-batch cultures (1 g/liter) with ethanol as the preferred carbon source

AXIN1 and AXIN2 variants in gastrointestinal cancers

AbstractMutations in the APC (adenomatous polyposis coli) gene, which encodes a multi-functional protein with a well-defined role in the canonical Wnt pathway, underlie familial adenomatous polypsosis, a rare, inherited form of colorectal cancer (CRC) and contribute to the majority of sporadic CRCs. However, not all sporadic and familial CRCs can be explained by mutations in APC or other genes with well-established roles in CRC. The AXIN1 and AXIN2 proteins function in the canonical Wnt pathway, and AXIN1/2 alterations have been proposed as key defects in some cancers. Here, we review AXIN1 and AXIN2 sequence alterations reported in gastrointestinal cancers, with the goal of vetting the evidence that some of the variants may have key functional roles in cancer development

Advances in Catalytic Routes for the Homogeneous Green Conversion of the Bio-Based Platform 5-Hydroxymethylfurfural

5-Hydroxymethylfufural (HMF) is an intriguing platform molecule that can be obtained from biomasses and that can lead to the production of a wide range of products, intermediates, or monomers. The presence of different moieties in HMF (hydroxy, aldehyde, furan ring) allows to carry out different transformations such as selective oxidations and hydrogenations, reductive aminations, etherifications, decarbonylations, and acetalizations. This is a great chance in a biorefinery perspective but requires the development of active and highly selective catalysts. In this view, homogeneous catalysis can lead to efficient conversion of HMF at mild reaction conditions. This Review discussed the recent achievements in homogeneous catalysts development and application to HMF transformations. The effects of metal nature, ligands, solvents, and reaction conditions were reported and critically reviewed. Current issues and future chances have been presented to drive future studies toward more efficient and scalable processes

Low mass dimuons within a hybrid approach

We analyse dilepton emission from hot and dense hadronic matter using a hybrid approach based on the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model with an intermediate hydrodynamic stage for the description of heavy-ion collisions at relativistic energies. Focusing on the enhancement with respect to the contribution from long-lived hadron decays after freeze-out observed at the SPS in the low mass region of the dilepton spectra (often referred to as "the excess"), the relative importance of the emission from the equilibrium and the non-equilibrium stages is discussed.Comment: Proceedings of Hot Quarks 2010, 21-26 June 2010 Las Londe Les Maures; v2: Corrected typos and added a commen

Stability of antiphase line defects in nanometer-sized boron-nitride cones

We investigate the stability of boron nitride conical sheets of nanometer size, using first-principles calculations. Our results indicate that cones with an antiphase boundary (a line defect that contains either B-B or N-N bonds) can be more stable than those without one. We also find that doping the antiphase boundaries with carbon can enhance their stability, leading also to the appearance of localized states in the bandgap. Among the structures we considered, the one with the smallest formation energy is a cone with a carbon-modified antiphase boundary that presents a spin splitting of about 0.5 eV at the Fermi level.Comment: 5 two-column pages with 2 figures Accepted for publication in Physical Review B (vol 70, 15 Nov.

Antagonists of the Receptor-G Protein Interface Block Gi-coupled Signal Transduction

The carboxyl terminus of heterotrimeric G protein alpha subunits plays an important role in receptor interaction. We demonstrate that peptides corresponding to the last 11 residues of Galphai1/2 or Galphao1 impair agonist binding to A1 adenosine receptors, whereas Galphas or Galphat peptides have no effect. Previously, by using a combinatorial library we identified a series of Galphat peptide analogs that bind rhodopsin with high affinity (Martin, E. L., Rens-Domiano, S., Schatz, P. J., and Hamm, H. E. (1996) J. Biol. Chem. 271, 361-366). Native Galphai1/2 peptide as well as several analogs were tested for their ability to modulate agonist binding or antagonist-agonist competition using cells overexpressing human A1 adenosine receptors. Three peptide analogs decreased the Ki, suggesting that they disrupt the high affinity receptor-G protein interaction and stabilize an intermediate affinity state. To study the ability of the peptides to compete with endogenous Galphai proteins and block signal transduction in a native setting, we measured activation of G protein-coupled K+ channels through A1 adenosine or gamma-aminobutyric acid, type B, receptors in hippocampal CA1 pyramidal neurons. Native Galphai1/2, peptide, and certain analog peptides inhibited receptor-mediated K+ channel gating, dependent on which receptor was activated. This differential perturbation of receptor-G protein interaction suggests that receptors that act on the same G protein can be selectively disrupted