Shock loss measurements in non-ideal supersonic flows of organic vapors

This paper presents the first ever direct measurements of total pressure losses across shocks in supersonic flows of organic vapors in non-ideal conditions, so in the thermodynamic region close to the liquid-vapor saturation curve and the critical point where the ideal gas law is not applicable. Experiments were carried out with fluid siloxane MM (hexamethyldisiloxane, C6H18OSi2), commonly employed in medium-/high-temperature organic Rankine cycles (ORCs), in the Test Rig for Organic VApors (TROVA), a blowdown wind tunnel at the Laboratory of Compressible fluid dynamics for Renewable Energy Applications (CREA lab) of Politecnico di Milano. A total pressure probe was inserted in superheated MM vapor flow at Mach number similar to 1.5 with total conditions in the range 215 - 230 degrees C and 2 - 12 bar at varying levels of non-ideality, with a compressibility factor evaluated at total conditions between Z(T) = 0.68 - 0.98. These operating conditions are representative of the first-stage stator of ORC turbines. Measured shock losses were compared with those calculated from pre-shock quantities by solving conservation equations across a normal shock, with differences always below 2% attesting a satisfactory reliability of the implemented experimental procedure. An in-depth analysis was then carried out, highlighting the direct effects of non-ideality on shock intensity. Even at the mildly non-ideal conditions with Z(T) greater than or similar to 0.70 considered here, non-ideality was responsible for a significantly stronger shock compared to the ideal gas limit at same pre-shock Mach number, with differences as large as 6%.[GRAPHICS]

Direct and indirect costs in the conservative management of undisplaced scaphoid fractures

The scaphoid is the most commonly fractured carpal bone, and preferable treatment of undisplaced fractures is controversial. In order to assess the socio-economic impact of treatment modalities, we analysed the cost of conservative management of 54 undisplaced scaphoid fractures. Global costs amounted to 14.077 Swiss francs (9385 euros) per patient. Direct costs represent only 10% of global costs. No significant correlation was found between costs and timing of diagnosis, hand dominance or complications. Thirty-four percent of patients were able to resume their job with the wrist immobilised without complication, but at an obvious impact on indirect and global costs. If early resumption of professional activities during conservative treatment of undisplaced scaphoid fractures does not impair successful fracture healing, patients should be encouraged to return to work as early as possible, as is routinely done after percutaneous fracture fixation. This will contribute to massively reducing the cost of conservative treatmen

Regulation of ykrL (htpX) by Rok and YkrK, a Novel Type of Regulator in Bacillus subtilis

Expression of ykrL of Bacillus subtilis, encoding a close homologue of the Escherichia coli membrane protein quality control protease HtpX, was shown to be upregulated under membrane protein overproduction stress. Using DNA affinity chromatography, two proteins were found to bind to the promoter region of ykrL: Rok, known as a repressor of competence and genes for extracytoplasmic functions, and YkrK, a novel type of regulator encoded by the gene adjacent to ykrL but divergently transcribed. Electrophoretic mobility shift assays showed Rok and YkrK binding to the ykrL promoter region as well as YkrK binding to the ykrK promoter region. Comparative bioinformatic analysis of the ykrL promoter regions in related Bacillus species revealed a consensus motif, which was demonstrated to be the binding site of YkrK. Deletion of rok and ykrK in a PykrL-gfp reporter strain showed that both proteins are repressors of ykrL expression. In addition, conditions which activated PykrL (membrane protein overproduction, dissipation of the membrane potential, and salt and phenol stress) point to the involvement of YkrL in membrane protein quality control

Experimental and numerical analysis of supersonic blade profiles developed for highly loaded impulse type steam turbine stages

The paper describes the results of a numerical and experimental research program addressing the aerodynamic investigation on the performance of blade profiles specifically developed for application in highly loaded impulse type turbine stages. The industrial requirements driving toward the adoption of highly loaded stage solutions are presented, along with an estimation of the profiles operating parameters. Two stator vanes and one rotor blade profile have been developed and extensively tested by means of flow field measurements and schlieren visualization in a transonic blow-down wind tunnel for linear cascades. Experimental results for the relevant operating conditions are presented, providing validation data for the CFD model used for blade design and evidencing that the main goals of the design optimization procedure have been achieved

Arabidopsis leaf plasma membrane proteome using a gel free method: Focus on receptor-like kinases

Abstract The hydrophobic proteins of plant plasma membrane still remain largely unknown. For example in the Arabidopsis genome, receptor-like kinases (RLKs) are plasma membrane proteins, functioning as the primary receptors in the signaling of stress conditions, hormones and the presence of pathogens form a diverse family of over 610 genes. A limited number of these proteins have appeard in protein profiles. The detection of these proteins and thus the determination of their dynamics and tissue specificity, is technically challenging due to their low abundance and association to a lipid membrane. To identify new putative membrane proteins especially receptor systems, we used a gel free proteomic strategy based on mass spectrometry analyses of a plasma membrane fraction enriched in hydrophobic proteins. We produced from Arabidopsis leaf a highly purified plasma membrane fraction with the aqueous two-phase partitioning technique. By separating the proteins in the plasma membrane fraction with ion exchange and reverse phase chromatography and analyzing the resulting fractions on a MALDI-TOF mass spectrometer, over 900 proteins were detected. The plasma membrane proteome generated by this approach contains numerous plasma membrane integral proteins, onethird displaying at least four trans-membrane segments. An in silico analysis shows a correlation between the putative functions of the identified proteins and the expected roles for plasma membrane in transport, signaling, cellular traffic and metabolism. Of these proteins, 304 were annotated as membrane proteins, 69 were RLKs, distributed among the different receptor families in proportions reflecting the distribution in the genome. Of the RLKs that were identified, most are reported for the first time at the protein level and will constitute interesting targets for further functional studies

Structure and mechanism of acetolactate decarboxylase

Acetolactate decarboxylase catalyzes the conversion of both enantiomers of acetolactate to the (R)-enantiomer of acetoin, via a mechanism that has been shown to involve a prior rearrangement of the non-natural (R)-enantiomer substrate to the natural (S)-enantiomer. In this paper, a series of crystal structures of ALDC complex with designed transition state mimics are reported. These structures, coupled with inhibition studies and site-directed mutagenesis provide an improved understanding of the molecular processes involved in the stereoselective decarboxylation/protonation events. A mechanism for the transformation of each enantiomer of acetolactate is proposed

Monitoring the FLASH Cryomodule Transportation from DESY Hamburg to CEA Saclay: Coupler Contact, Vacuum, Acceleration and Vibration Analysis

With a view to the series production of one hundred, 12 m long XFEL 1.3 GHz cryomodules and their transportation from the assembly site at CEA Saclay (F) to the installation site at DESY Hamburg (D) a test transportation of a FLASH cryomodule has been performed, in the condition foreseen for the mass transportation. The present study examines the stresses induced on the module and verifies the damping capabilities of the transport frame in order to minimize risk of damage to the most critical components. During the transportation, acceleration and vibration have been monitored as well as coupler antenna contacts and vacuum performances. This paper describes the analysis performed and compares those results to the data of a similar transportation study at Fermilab for the CM1 cryomodule