Why do we flush gas in gaseous detectors? Procureur, S.; Attié, D.; Bouteille, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2020, Volume:
955
Journal Article
Peer reviewed
Open access
The effects and the origin of the gas degradation in a gaseous detector-based tracker are investigated. The study focused on the so-called T2K gas, which turned out to be highly sensitive to ...pollutants. In particular the H2O and O2 concentrations were monitored online in different conditions to establish their influence on the gain of the detectors. This pollution was first mitigated by a recirculating and accelerating gas system with the use of a turbine and different absorbers. Further measurements revealed that this pollution originates from a continuous permeation process through the different materials of the gas circuit. In particular, polyurethane-based gas pipes or polyester materials largely increase the level of humidity. As a direct consequence of this work, the gas autonomy of the muon telescopes currently deployed inside the Khufu’s pyramid have been dramatically improved.
The nicotinamide adenine dinucleotide phosphate (NADPH)-dependent enzyme dihydroflavonol 4-reductase (DFR) catalyzes a late step in the biosynthesis of anthocyanins and condensed tannins, two ...flavonoid classes of importance to plant survival and human nutrition. This enzyme has been widely investigated in many plant species, but little is known about its structural and biochemical properties. To provide a basis for detailed structure–function studies, the crystal structure of
Vitis vinifera DFR, heterologously expressed in
Escherichia coli, has been determined at 1.8 Å resolution. The 3D structure of the ternary complex obtained with the oxidized form of nicotinamide adenine dinucleotide phosphate and dihydroquercetin, one of the DFR substrates, presents common features with the short-chain dehydrogenase/reductase family, i.e., an N-terminal domain adopting a Rossmann fold and a variable C-terminal domain, which participates in substrate binding. The structure confirms the importance of the 131–156 region, which lines the substrate binding site and enlightens the role of a specific residue at position 133 (Asn or Asp), assumed to control substrate recognition. The activity of the wild-type enzyme and its variant N133D has been quantified
in vitro, using dihydroquercetin or dihydrokaempferol. Our results demonstrate that position 133 cannot be solely responsible for the recognition of the B-ring hydroxylation pattern of dihydroflavonols.
Potential applications of muon tomography, or muography, as non-invasive scanning method have increased in the last years together with the performance of the particle detectors used for muon ...detection, known as muon telescopes. A new concept muon telescope is presented, which could enlarge even more the range of application of this technique. It is based on a compact TPC equipped with a 2D pixelized Micromegas detector with multiplexed readout. This detector will overcome some of the constraints of the instruments currently used, as they limited acceptance, while keeping other features required for muography as stability, robustness or portability. Moreover, it will be capable to reconstruct the 3D direction of the incident muons with a single instrument. With its design and features, this kind of detectors can be fitted at boreholes from where they can scan the surroundings, being an interesting technique for mining exploration, geotechnics or monitoring of dykes or bridges which has arouse the interest of industry. In a further phase it is expected to develop a network of these detectors which will allow the 3D reconstruction of the studied object by the combination of the images registered by each of the telescopes. Main features and first tests and results of this new instrument will be presented together with some studies, performed by Monte Carlo simulations, of the capabilities of this muon telescope and the analysis principle.
A graded TiCxN1−x coating with x varying parabolically in the range 0–1 was grown by chemical vapor deposition in the TiCL4–CH4–N2–H2 system by quasi-continuously changing process parameters (growth ...time, CH4 mole fraction) at 1400K and at 10.7kPa. Taper polishing of the graded coating was carried out by a simple apparatus converting a depth dimension into a lateral dimension. Auger electron spectroscopy line scan was then performed on the taper polished surface. Composition profile of the graded coating was determined to be in agreement with the designed one using surface profilometer traces and AES signals from CKLL transition at 272eV. AES/taper polishing approach facilitates composition–depth analysis with a minimal degree of sputtering and a substantial reduction of data acquisition time. Taper polishing could also be combined with other chemical analysis techniques such as X-ray microdiffraction.
Introduction:
Standardized handoffs reduce medical errors and prevent adverse events or near misses. This article describes a quality improvement initiative implementing a unique standardized handoff ...tool and process to transition from the operating room to the neonatal intensive care unit (NICU) at a level-four regional center with many inpatients requiring surgical intervention. Before this project, there was no standardized handoff tool or process for postsurgical transitions. The primary aim was to achieve 80% compliance with completing a structured postoperative OR to NICU handoff tool within 12 months of implementation.
Methods:
An interdisciplinary team developed and implemented a standardized NICU postoperative handoff tool and process that requires face-to-face communication, defines team members who should be present, and highlights communication with the family. In addition, the handoff tool compliance and process measures were monitored, evaluated, and audited.
Results:
Although not consistent, we achieved eighty percent compliance with the outcome measures using the handoff tool. We did not sustain 80% of appropriate providers present at handoff. In addition, insufficient data assess overall parental satisfaction with the surgical experience. Although improved, the process measure of immediate postoperative family updates did not reach the targeted goal. However, the balancing measure of staff experience and satisfaction did improve.
Conclusion:
Implementing a standardized handoff tool and process with an interdisciplinary and interdepartmental collaboration improves critical patient transitions from the operating room to the NICU.
Mapacalcine is a small homodimeric protein of 19 kDa with 9 disulfide bridges extracted from the
sponge (Red Sea). It selectively blocks a calcium current insensitive to most calcium blockers. ...Specific receptors for mapacalcine have been described in a variety of tissues such as brain, smooth muscle, liver, and kidney. Previous works achieved on hepatocytes and nervous cells demonstrated that this protein selectively blocks a calcium influx triggered by an ischemia/reperfusion (I/R) shock and efficiently protects cells from death after I/R. The aim of this work was to produce the recombinant mapacalcine in the yeast
. Mass spectrometry, light scattering analysis and biological characterization demonstrated that the recombinant mapacalcine obtained was a monomeric form with 4 disulfide bridges which retains the biological activity of the natural protein.
Horse‐spleen apoferritin is known to crystallize in three different space groups, cubic F432, tetragonal P4212 and orthorhombic P21212. A structure comparison of the cubic and tetragonal forms is ...presented here. Both crystal forms were obtained by the vapor‐diffusion technique and data were collected at 2.26 Å (cubic crystal) and 2.60 Å (tetragonal crystal) resolution. Two main differences were observed between these crystal structures: (i) whereas intermolecular contacts only involve salt‐bridge type interactions via cadmium ions in the cubic structure, two types of interactions are observed in the tetragonal crystal (cadmium‐ion‐mediated salt bridges and hydrogen‐bonding interactions) and (ii) cadmium ions bound in the threefold axes of ferritin molecules exhibit lower site‐occupation factors in the tetragonal structure than in the cubic one.
Phosphoinositide lipids recruit proteins to the plasma membrane involved in the regulation of cytoskeleton organization and in signalling pathways that control cell polarity and growth. Among those, ...Rgd1p is a yeast GTPase-activating protein (GAP) specific for Rho3p and Rho4p GTPases, which control actin polymerization and stress signalling pathways. Phosphoinositides not only bind Rgd1p, but also stimulate its GAP activity on the membrane-anchored form of Rho4p. Both F-BAR (F-BAR FCH, and BAR) and RhoGAP domains of Rgd1p are involved in lipid interactions. In the Rgd1p-F-BAR domain, a phosphoinositide-binding site has been recently characterized. We report here the X-ray structure of the Rgd1p-RhoGAP domain, identify by NMR spectroscopy and confirm by docking simulations, a new but cryptic phosphoinositide-binding site, comprising contiguous A1, A1' and B helices. The addition of helix A1', unusual among RhoGAP domains, seems to be crucial for lipid interactions. Such a site was totally unexpected inside a RhoGAP domain, as it was not predicted from either the protein sequence or its three-dimensional structure. Phosphoinositide-binding sites in RhoGAP domains have been reported to correspond to polybasic regions, which are located at the unstructured flexible termini of proteins. Solid-state NMR spectroscopy experiments confirm the membrane interaction of the Rgd1p-RhoGAP domain upon the addition of PtdIns(4,5)P
and indicate a slight membrane destabilization in the presence of the two partners.
Pure metal/oxide interfacial energies are characterized by weak Van der Waals and electronic interactions. The intrinsic contact angles in these systems are larger than 90 deg . The roughness of the ...ceramic increases the apparent contact angle and may lead to the formation of composite surfaces that are not fully penetrated by the metal. Oxygen dissolved in the metal adsorbs at the liquid metal/vapor and the liquid metal/ceramic interfaces, leading to improved wetting with contact angles as low as 70 deg . Statistical thermodynamic models of the interfaces are in good agreement with the experimental adsorption isotherms. The combination of a metallic ternary addition and dissolved oxygen offers the potential for increased wetting, but the identification of suitable additions remains elusive. Increases in temperature lead to modest decreases in contact angle, and do not appear to be a practical route to improved wetting in nonreactive systems. Materials discussed include Au/Al sub 2 O sub 3 , Cu/Al sub 2 O 3 , and Ag-O/Al sub 2 O sub 3 systems.
PDF
