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Room-Temperature Decarboxylative Alkynylation of Carboxylic Acids Using Photoredox Catalysis and EBX Reagents
No full textAlkynes are used as building blocks in synthetic and medicinal chemistry, chemical biology, and materials science. Therefore, efficient methods for their synthesis are the subject of intensive research. Herein, we report the direct synthesis of alkynes from readily available carboxylic acids at room temperature under visible-light irradiation. The combination of an iridium photocatalyst with ethynylbenziodoxolone (EBX) reagents allowed the decarboxylative alkynylation of carboxylic acids in good yields under mild conditions. The method could be applied to silyl-, aryl-, and alkyl- substituted alkynes. It was particularly successful in the case of alpha-amino and alpha-oxo acids derived from biomass.LCS
Endoplasmic Reticulum Stress Is Important for the Manifestations of alpha-Synucleinopathy In Vivo
No full textAccumulation of misfolded alpha-synuclein (alpha S) is mechanistically linked to neurodegeneration in Parkinson's disease (PD) and other alpha-synucleinopathies. However, how alpha S causes neurodegeneration is unresolved. Because cellular accumulation of misfolded proteins can lead to endoplasmic reticulum stress/unfolded protein response (ERS/UPR), chronic ERS could contribute to neurodegeneration in alpha-synucleinopathy. Using the A53T mutant human alpha S transgenic (A53T alpha STg) mouse model of alpha-synucleinopathy, we show that disease onset in the alpha S Tg model is coincident with induction of ER chaperones in neurons exhibiting alpha S pathology. However, the neuronal ER chaperone induction was not accompanied by the activation of phospho-eIF2 alpha, indicating that alpha-synucleinopathy is associated with abnormal UPR that could promote cell death. Induction of ERS/UPR was associated with increased levels of ER/microsomal (ER/M) associated alpha S monomers and aggregates. Significantly, human PD cases also exhibit higher relative levels of ER/M alpha S than the control cases. Moreover, alpha S interacts with ER chaperones and overexpression of alpha S sensitizes neuronal cells to ERS-induced toxicity, suggesting that alpha S may have direct impact on ER function. This view is supported by the presence of ERS-activated caspase-12 and the accumulation of ER-associated polyubiquitin. More important, treatment with Salubrinal, an anti-ERS compound, significantly attenuates disease manifestations in both the A53T alpha S Tg mouse model and the adeno-associated virus-transduced rat model of A53T alpha S-dependent dopaminergic neurodegeneration. Our data indicate that the accumulation alpha S within ER leads to chronic ER stress conditions that contribute to neurodegeneration in alpha-synucleinopathies. Attenuating chronic ERS could be an effective therapy for PD and other alpha-synucleinopathies.LE
The Schizosaccharomyces pombe septation initiation network (SIN) is required for spore formation in meiosis
No full textWhen nutrients are abundant, S. pombe cells grow as rods, dividing by fission after formation of a medially placed cell wall or division septum. Septum formation is triggered by a group of proteins, called the septation initiation network or SIN, that trigger contraction of the acto-myosin contractile ring at the end of mitosis. Ectopic activation of the SIN can uncouple septum formation from other cell-cycle events, whereas loss of SIN signalling gives rise to multinucleated cells due to the failure of cytokinesis. When starved, S. pombe cells of opposite mating types fuse to form a diploid zygote that undergoes meiosis and produces four spores. No septa or contractile rings are formed during meiosis. In this study, we have investigated the role of the SIN in meiosis. Our data show that, whereas the meiotic divisions appear normal, SIN mutants cannot form spores. Forespore membrane formation is initiated, but the nuclei are not encapsulated properly. The SIN proteins localise to the spindle pole body in meiosis. The protein kinases Sid1p and Cdc7p do not associate with the spindle pole body until meiosis II, when forespore membrane deposition begins. These data indicate a role for the SIN in regulating spore formation during meiosis.UPSI
Options to correct local turbulent flux measurements for large-scale fluxes using an approach based on large-eddy simulation
No full textThe eddy-covariance method provides the most direct estimates for fluxes between ecosystems and the atmosphere. However, dispersive fluxes can occur in the presence of secondary circulations, which can inherently not be captured by such single-tower measurements. In this study, we present options to correct local flux measurements for such large-scale transport based on a non-local parametric model that has been developed from a set of idealized large-eddy simulations. This method is tested for three real-world sites (DK-Sor, DE-Fen, and DE-Gwg), representing typical conditions in the mid-latitudes with different measurement heights, different terrain complexities, and different landscape-scale heterogeneities. Two ways to determine the boundary-layer height, which is a necessary input variable for modelling the dispersive fluxes, are applied, which are either based on operational radio soundings and local in situ measurements for the flat sites or from backscatter-intensity profiles obtained from co-located ceilometers for the two sites in complex terrain. The adjusted total fluxes are evaluated by assessing the improvement in energy balance closure and by comparing the resulting latent heat fluxes with evapotranspiration rates from nearby lysimeters. The results show that not only the accuracy of the flux estimates is improved but also the precision, which is indicated by RMSE values that are reduced by approximately 50 %. Nevertheless, it needs to be clear that this method is intended to correct for a bias in eddy-covariance measurements due to the presence of large-scale dispersive fluxes. Other reasons potentially causing a systematic underestimated or overestimation, such as low-pass filtering effects and missing storage terms, still need to be considered and minimized as much as possible. Moreover, additional transport induced by surface heterogeneities is not considered.WIR
Fibertract segmentation in position orientation space from high angular resolution diffusion MRI
No full textIn diffusion MRI, standard approaches for fibertract identification are based on algorithms that generate lines of coherent diffusion, currently known as tractography. A tract is then identified as a set of such lines selected on some criteria. In the present study, we investigate whether fibertract identification can be formulated as a segmentation task that recognizes a fibertract as a region where diffusion is intense and coherent. Indeed, we show that it is possible to segment efficiently well-known fibertracts with classical image processing methods provided that the problem is formulated in a five-dimensional space of position and orientation. As an example, we choose to adapt to this newly defined high-dimensional non-Euclidean space, called position orientation space, an algorithm based on the hidden Markov random field framework. Structures such as the cerebellar peduncles, corticospinal tract, association bundles can be identified and represented in three dimensions by a back projection technique similar to maximum intensity projection. Potential advantages and drawbacks as compared to classical tractography are discussed; for example, it appears that our formulation handles naturally crossing tracts and is not biased by human intervention.LTS
Applications of a robust state estimator to the EEF power system
No full textThe EEF utility, which has its headquarters in Fribourg, Switzerland, is planning to install in its new energy management system a robust Schweppe-type Huber GM-state estimator (SHGM). Prior to the installation, the iterative algorithm that implements the estimator has been upgraded to meet the specifications and extensive offline simulations have been carried out on the EEF power network. This power system consists of 3 islands and 33 substations that are interconnected by 60 kV subtransmission lines. The islands may from time to time be interconnected. Simulations revealed that the SHGM algorithm exhibits excellent convergence properties and is robust to bad measurements, be they leverage points or not. Installation of the state estimator on the computer facilities located at the new EEF control center will take place in the summer of 1998, followed by its full real-time testingLREDES
Void Fraction and Two-Phase Pressure Drops for Evaporating Flow over Horizontal Tube Bundles
No full textLTC
Multi-slit triode ion optical system with ballistic beam focusing
No full textMulti-slit triode ion-optical systems with spherical electrodes are of interest for formation of intense focused neutral beams for plasma heating. At present, two versions of focusing multi-slit triode ion optical system are developed. The first ion optical system forms the proton beam with 15 keV energy, 140 A current, and 30 ms duration. The second ion optical system is intended for heating neutral beam injector of Tokamak Configuration Variable (TCV). The injector produces focused deuterium neutral beam with 35 keV energy, 1MWpower, and 2 s duration. In the later case, the angular beam divergence of the neutral beam is 20-22 mrad in the direction across the slits of the ion optical system and 12 mrad in the direction along the slits. (C) 2015 AIP Publishing LLC.SP
DEMOSITE - Site de démonstration d'éléments de construction photovoltaïques intégrés au bâtiment
No full textLe développement de l'utilisation du photovoltaïque dans les pays industrialisés, et en Suisse en particulier, passe par son intégration architecturale au bâtiment. Ce mode de faire permet d'une part de fournir d'importantes surfaces de captage à proximité du consommateur, et d'autre part de réduire les coûts d'infrastructure, l'élément photovoltaïque devenant un élément de construction. Afin de stimuler ce développement, il est important que les architectes, maîtres de l'ouvrage et autres acteurs du processus constructif connaissent les éléments photovoltaïques existants, puissent voir de quelle manière ces éléments s'intègrent au bâtiment, finalement soient renseignés sur l'énergie électrique qu'ils peuvent en attendre. C'est dans ce but que le site international d'exposition et de démonstration d'éléments de construction photovoltaïques DEMOSITE a été mis sur pied et exploité à l'EPFL, dans le cadre de la tâche XVI de l'Agence Internationale de l'Energie.LESO-P