7,002 research outputs found
An Internal Variable Approach to the Superplastic Deformation Behavior of a Pb-Sn Eutectic Alloy
No full textEXPERIMENTAL INVESTIGATION ON THERMOHYDRODYNAMIC PERFORMANCE OF LARGE TILTING-PAD JOURNAL BEARING INCLUDING THE INLET PRESSURE EFFECT
No full textThe thermohydrodynamic performance of a large tilting-pad journal bearing including the inlet pressure effect is investigated experimentally. The continuous film pressure, film thickness and shaft surface temperature, and bearing surface temperature are measured along with the shaft speed and the bearing load for various flow rates. Considerably large inlet pressure is observed at the entrance of each pad, especially the lower pads. The inlet pressure is increased by the increase of shaft speed as well as bearing load, but is almost independent of the flow rate. The upper pads always maintain a slight wedge film shape owing ta the inlet pressure, and scraping is not observed in the upper pads. It is observed that the shaft surface temperature is constant in the circumferential direction and increases with the increase of shaft speed in both low and high shaft-speed regions; however, there exists a transition region where the shaft surface temperature decreases with the increase of shaft speed
INLET PRESSURE EFFECTS ON THE THERMOHYDRODYNAMIC PERFORMANCE OF A LARGE TILTING-PAD JOURNAL BEARING
No full textInlet pressure effects on the thermohydrodynamic performance of a 4-pad large tilting pad journal bearing are investigated both theoretically and experimentally. The theory takes into account the inlet pressure and the three-dimensional variation of oil viscosity and eddy viscosity. Film pressure, film thickness, bearing metal temperature, load capacity, and eccentricity are measured by experiments. A noticeable inlet pressure rise is observed at the entrance of pads. It is shown that the inlet pressure increases not only the film pressure and the load capacity but also the supply flow rate, while if decreases the mixing and bearing surface temperature. The bearing characteristics predicted by the turbulent thermohydrodynamic theory, including the inlet pressure, are in good agreement with the experimental results. Therefore it can be suggested that the inlet pressure must be taken into account in theoretical calculations in order to predict the thermohydrodynamic performance of large tilting pad journal bearings accurately
Immunization coverage and risk factors for failure to immunize within the Expanded Programme on Immunization in Kenya after introduction of new Haemophilus influenzae type b and hepatitis b virus antigens
No full textBackground: Kenya introduced a pentavalent vaccine including the DTP, Haemophilus influenzae type b and hepatitis b virus antigens in Nov 2001 and strengthened immunization services. We estimated immunization coverage before and after introduction, timeliness of vaccination and risk factors for failure to immunize in Kilifi district, Kenya.
Methods: In Nov 2002 we performed WHO cluster-sample surveys of > 200 children scheduled for vaccination before or after introduction of pentavalent vaccine. In Mar 2004 we conducted a simple random sample (SRS) survey of 204 children aged 9 - 23 months. Coverage was estimated by inverse Kaplan-Meier survival analysis of vaccine- card and mothers' recall data and corroborated by reviewing administrative records from national and provincial vaccine stores. The contribution to timely immunization of distance from clinic, seasonal rainfall, mother's age, and family size was estimated by a proportional hazards model.
Results: Immunization coverage for three DTP and pentavalent doses was 100% before and 91% after pentavalent vaccine introduction, respectively. By SRS survey, coverage was 88% for three pentavalent doses. The median age at first, second and third vaccine dose was 8, 13 and 18 weeks. Vials dispatched to Kilifi District during 2001 - 2003 would provide three immunizations for 92% of the birth cohort. Immunization rate ratios were reduced with every kilometre of distance from home to vaccine clinic (HR 0.95, CI 0.91 - 1.00), rainy seasons ( HR 0.73, 95% CI 0.61 - 0.89) and family size, increasing progressively up to 4 children ( HR 0.55, 95% CI 0.41 - 0.73).
Conclusion: Vaccine coverage was high before and after introduction of pentavalent vaccine, but most doses were given late. Coverage is limited by seasonal factors and family siz
Observation of hc radiative decay hc › ??' and evidence for hc › ??
No full textKolcu, Onur Buğra (Arel Author) --- Makale 69 yazarlıdır.A search for radiative decays of the P-wave spin singlet charmonium resonance hc is performed based on 4.48 × 108 ? events collected with the BESIII detector operating at the BEPCII storage ring. Events of the reaction channels hc › ??' and ?? are observed with a statistical significance of 8.4? and 4.0?, respectively, for the first time. The branching fractions of hc › ??' and hc › ?? are measured to be B(hc › ??' ) = (1.52±0.27±0.29)×10-3 and B(hc › ??) = (4.7±1.5±1.4)×10-4 , respectively, where the first errors are statistical and the second are systematic uncertainties
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Hyaluronic acid synthesis, degradation, and crosslinking in equine osteoarthritis: TNF-α-TSG-6-mediated HC-HA formation
No full textBackground
TNF-α-stimulated gene 6 (TSG-6) protein, a TNF-α-responsive hyaladherin, possesses enzymatic activity that can catalyze covalent crosslinks of the polysaccharide hyaluronic acid (HA) to another protein to form heavy chain-hyaluronic acid (HC-HA) complexes in pathological conditions such as osteoarthritis (OA). Here, we examined HA synthase and inflammatory gene expression; synovial fluid HA, TNF-α, and viscosity; and TSG-6-mediated HC-HA complex formation in an equine OA model. The objectives of this study were to (1) evaluate the TNF-α-TSG-6-HC-HA signaling pathway across multiple joint tissues, including synovial membrane, cartilage, and synovial fluid, and (2) determine the impact of OA on synovial fluid composition and biophysical properties.
Methods
HA and inflammatory cytokine concentrations (TNF-α, IL-1β, CCL2, 3, 5, and 11) were analyzed in synovial fluid from 63 OA and 25 control joints, and HA synthase (HAS1-3), TSG-6, and hyaluronan-degrading enzyme (HYAL2, HEXA) gene expression was measured in synovial membrane and cartilage. HA molecular weight (MW) distributions were determined using agarose gel electrophoresis and solid-state nanopore measurements, and HC-HA complex formation was detected via immunoblotting and immunofluorescence. SEC-MALS was used to evaluate TSG-6-mediated HA crosslinking, and synovial fluid and HA solution viscosities were analyzed using multiple particle-tracking microrheology and microfluidic measurements, respectively.
Results
TNF-α concentrations were greater in OA synovial fluid, and TSG6 expression was upregulated in OA synovial membrane and cartilage. TSG-6-mediated HC-HA complex formation was greater in OA synovial fluid and tissues than controls, and HC-HA was localized to both synovial membrane and superficial zone chondrocytes in OA joints. SEC-MALS demonstrated macromolecular aggregation of low MW HA in the presence of TSG-6 and inter-α-inhibitor with concurrent increases in viscosity.
Conclusions
Synovial fluid TNF-α concentrations, synovial membrane and cartilage TSG6 gene expression, and HC-HA complex formation were increased in equine OA. Despite the ability of TSG-6 to induce macromolecular aggregation of low MW HA with resultant increases in the viscosity of low MW HA solutions in vitro, HA concentration was the primary determinant of synovial fluid viscosity rather than HA MW or HC-HA crosslinking. The TNF-α-TSG-6-HC-HA pathway may represent a potential therapeutic target in OA
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