1,390 research outputs found
Two-dimensional transonic testing with splitter plates
The use of splitter plates for two dimensional transonic testing in wind tunnels was investigated on a 12% biconvex airfoil section over the Mach number range 0.6 to 1.0. Measured pressure distributions were compared to transonic theory and to other experiments, including an investigation in the same facility without splitter plates. The results of the experiment show the best agreement with theory over the entire transonic Mach number range
Design, development and performance study of six-gap glass MRPC detectors
The Multigap Resistive Plate Chambers (MRPCs) are gas ionization detectors
with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV)
is applied on the outer surfaces of outermost resistive plates only, while the
interior plates are left electrically floating. The presence of multiple narrow
sub--gaps with high electric field results in faster signals on the outer
electrodes, thus improving the detector's time resolution. Due to their
excellent performance and relatively low cost, the MRPC detector has found
potential application in Time-of-Flight (TOF) systems. Here we present the
design, fabrication, optimization of the operating parameters such as the HV,
the gas mixture composition, and, performance of six--gap glass MRPC detectors
of area 27cm 27 cm, which are developed in order to find application
as trigger detectors, in TOF measurement etc. The design has been optimized
with unique spacers and blockers to ensure a proper gas flow through the narrow
sub-gaps, which are 250 m wide. The gas mixture consisting of R134A,
Isobutane and SF, and the fraction of each constituting gases has been
optimized after studying the MRPC performance for a set of different
concentrations. The counting efficiency of the MRPC is about 95% at kV.
At the same operating voltage, the time resolution, after correcting for the
walk effect, is found to be about ps.Comment: Revised version with 15 pages, 14 figures, 2 tables. Accepted for
publication in the European Physical Journal
Comparison of Damage Path Predictions for Composite Laminates by Explicit and Standard Finite Element Analysis Tools
Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it
Micellar Nanocarriers of Hydroxytyrosol Are Protective against Parkinson’s Related Oxidative Stress in an In Vitro hCMEC/D3-SH-SY5Y Co-Culture System
Hydroxytyrosol (HT) is a natural phenolic antioxidant which has neuroprotective effects in models of Parkinson’s disease (PD). Due to issues such as rapid metabolism, HT is unlikely to reach the brain at therapeutic concentrations required for a clinical effect. We have previously developed micellar nanocarriers from Pluronic F68® (P68) and dequalinium (DQA) which have suitable characteristics for brain delivery of antioxidants and iron chelators. The aim of this study was to utilise the P68 + DQA nanocarriers for HT alone, or in combination with the iron chelator deferoxamine (DFO), and assess their physical characteristics and ability to pass the blood–brain barrier and protect against rotenone in a cellular hCMEC/D3-SH-SY5Y co-culture system. Both HT and HT + DFO formulations were less than 170 nm in size and demonstrated high encapsulation efficiencies (up to 97%). P68 + DQA nanoformulation enhanced the mean blood–brain barrier (BBB) passage of HT by 50% (p 0.0001, n = 6). This resulted in increased protection against rotenone induced cytotoxicity and oxidative stress by up to 12% and 9%, respectively, compared to the corresponding free drug treatments (p 0.01, n = 6). This study demonstrates for the first time the incorporation of HT and HT + DFO into P68 + DQA nanocarriers and successful delivery of these nanocarriers across a BBB model to protect against PD-related oxidative stress. These nanocarriers warrant further investigation to evaluate whether this enhanced neuroprotection is exhibited in in vivo PD models
Prescribing pattern of drugs in chronic kidney disease patients on hemodialysis at a tertiary care hospital
Background: CKD (chronic kidney disease) is a general term for heterogeneous disorders affecting kidney structure and its function. It is defined as either kidney damage or a decreased glomerular filtration rate of less than 60 mL/min/1.73m2 for 3 or more months. Objective of present work is to study the drug utilization pattern in chronic kidney disease patients undergoing hemodialysis.Methods: After taking the clearance and approval from the institutional ethics committee, a cross sectional prospective observational study conducted on chronic kidney disease (CKD) patients undergoing hemodialysis, in the department of nephrology, of Rajarajeshwari Medical College and Hospital, Bangalore. The data was analyzed descriptively.Results: Study included 52 patients, among them 41 males, 11were females, with a mean age of 47.6yrs. In our study large number pt were suffering from hypertension (HTN) 88.46% (46), in them the calcium channel blocker (CCB) 08.48% (38) was most commonly prescribed anti hypertensive drug. Around 1/3 of pt suffering from diabetes mellitus (DM) 36.53% (19) most of these patients were treated with them treated with oral hypoglycemic agents (OHA), and less than half of pt treated with insulin01.56% (07). Other drugs like phosphate binders (calcium carbonate & acetate) used in 11.16% (50), aspirin in 08.70% (39), statins in 10.04% (45) pt were being most commonly prescribed drugs. Totally 448 drugs were prescribed In 52 pts Ie about 8.61 drugs / prescription, showing poly pharmacy.Conclusions: Patients undergoing hemodialysis with CKD will be having multiple diseases associated, regular monitoring and counseling regarding these diseases and its complication may reduce the incidence of CKD and the mortality and morbidity associated. The poly pharmacy noted in the study found inevitable because of the multifactorial etiologiesinvolved and needful multi-interventional approach towards it
Influence of Shear Stiffness Degradation on Crack Paths in Uni-Directional Composite Laminates
Influence of shear stiffness degradation in an element, due to damage, on crack paths in uni-directional laminates has been demonstrated. A new shear stiffness degradation approach to improve crack path prediction has been developed and implemented in an ABAQUS/Explicit frame work using VUMAT. Three progressive failure analysis models, built-in ABAQUS (TradeMark), original COmplete STress Reduction (COSTR) and the modified COSTR damage models have been utilized in this study to simulate crack paths in five unidirectional notched laminates, 15deg, 30deg, 45deg, 60deg and 75deg under uniaxial tension load. Results such as crack paths and load vs. edge displacement curves are documented in this report. Modified COSTR damage model shows better accuracy in predicting crack paths in all the uni-directional laminates compared to the ABAQUS (TradeMark) and the original COSTR damage models
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