69 research outputs found
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Development of phased array probes to operate in time-of-flight diffraction configuration to continuously monitor defect growth in thermal power plants
A high temperature (HT) structural health monitoring system for pipes that utilises phased array (PA) probes in time-of-flight diffraction (TOFD) configuration to continuously monitor the defect growth over time is being developed, so that when the defect reaches a critical size the plant can be shut down and maintenance can take place before failure. The numerical models for PA/TOFD inspection technique in either symmetric or asymmetric pitch-catch configuration were developed using the CIVA simulation platform. The probe characteristics were selected and the ultrasonic beam profile was predicted for different points in the volume of interest i.e. the weld and the heat affected zone (HAZ). The probes positions and interspacing between the probes in emission and reception were also selected in order to achieve maximum inspection coverage. The PA probes use piezoelectric elements for generation and reception of ultrasound beam. Single crystal gallium orthophosphate (GaPO4) has been selected for impedance analysis as a candidate for application in the PA probes operating at HT. Impedance characteristics of GAPO4 elements were investigated up to 580°C and together with measured capacitance (at 1 kHz), density and dimensions of the GAPO4 elements used to calculate material properties of these elements at HT as a function of time. The calculated material properties were used to evaluate the developed PA on TOFD technique at HT using COMSOL simulation package. The simulated and experimental results are encouraging for proceeding with development of PA/TOFD probes using GaPO4, for inspection and condition monitoring of HT pipelines in power plants at temperatures up to 580°C.European Commission through the FP7 Programme (FP7-SME-2013-1) under the grant agreement no. 605267, iKnowHow Informatics, CeramTec, InnoTecUK, Brunel University, Enkon, Vermon, Tecnitest Ingenieros and INETEC
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Assessment of material properties of gallium orthophosphate piezoelectric elements for development of phased array probes for continuous operation at 580 degrees C
In this paper, the thickness extension mode gallium orthophosphate single crystal
elements were characterised using the impedance analyser. Impedance characteristics of piezoelectric elements were investigated at temperatures from 25°C up to 580°C at first and then at a constant temperature of 580°C for a period of 25 days. The resonant and anti-resonant frequencies extracted from the impedance characteristics, capacitance (measured at 1 kHz), density and dimensions of the gallium orthophosphate elements were used to calculate electromechanical, piezoelectric and elastic properties of these elements at high temperatures as a function of time. The tested gallium orthophosphate elements proved to possess very stable efficiency and sensing capability when subjected to high temperature. The results are very encouraging for proceeding with development of phased array probes using gallium
orthophosphate, for inspection and condition monitoring of high temperature pipelines in
power plants at a temperature up to 580°C
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Autonomous ice protection combining ultrasonic guided waves and electrothermal systems
Meeting abstractInnovate U
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High temperature gallium orthophosphate transducers for NDT and monitoring purposes in nuclear power plants
There is a need for ultrasonic transducers to operate at temperatures up to 580°C for NDT and monitoring purposes in nuclear power plants. One of the key aspects of designing such transducers using high temperature (HT) piezoelectric single crystal material gallium orthophosphate - GaPO4 has been studied: ultrasonic performance of this piezoelectric material at HT as a function of time. An experimental setup was used where two thickness extension mode GaPO4 plates operating at frequency of 2.17 MHz were bonded to a carbon steel block using HT silver adhesive and these were placed in an electric furnace. HT wiring led from the piezoelectric plates through an opening in the furnace outside to an ultrasonic testing device. The ultrasonic measurements show that GaPO4 works as a functional ultrasonic transducer generating and receiving ultrasound at the temperature of 580°C for 13 consecutive days when HT corrosion of carbon steel block occurred leading to failure of the experiment. From the aspect of HT operation of this piezoelectric material, the results are very encouraging for proceeding with development of ultrasonic transducers using GaPO4 for application in nuclear power plants
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Development of low frequency high temperature ultrasonic transducers for in-service monitoring of pipework in power plants
In this paper, a low-frequency (20-100 kHz) long-range ultrasonic guided wave transducer for in-service structural health monitoring of high temperature pipework in power plants has been developed. The transducer is designed for continuous operation at a target temperature of 350 °C. This paper describes the methodology followed to develop and test the high temperature transducer. The method includes selection of the suitable piezoelectric material and characterisation of their high temperature properties for the desired thickness-shear mode of vibration to validate its performance at the target temperature. The assembly procedure established for manufacturing transducer is discussed. Ultrasonic performance of the developed transducer was examined and has demonstrated its application for in-service monitoring of pipework operating at the target temperature
Building Babies - Chapter 16
In contrast to birds, male mammals rarely help to raise the offspring. Of all mammals, only among rodents, carnivores, and primates, males are sometimes intensively engaged in providing infant care (Kleiman and Malcolm 1981). Male caretaking of infants has long been recognized in nonhuman primates (Itani 1959). Given that infant care behavior can have a positive effect on the infant’s development, growth, well-being, or survival, why are male mammals not more frequently involved in “building babies”? We begin the chapter defining a few relevant terms and introducing the theory and hypotheses that have historically addressed the evolution of paternal care. We then review empirical findings on male care among primate taxa, before focusing, in the final section, on our own work on paternal care in South American owl monkeys (Aotus spp.). We conclude the chapter with some suggestions for future studies.Deutsche Forschungsgemeinschaft (HU 1746/2-1)
Wenner-Gren Foundation, the L.S.B. Leakey Foundation, the National Geographic Society, the National Science Foundation (BCS-0621020), the University of Pennsylvania Research Foundation, the Zoological Society of San Dieg
Keeping the Vimentin Network under Control: Cell–Matrix Adhesion–associated Plectin 1f Affects Cell Shape and Polarity of Fibroblasts
Mature focal adhesions and fibrillar adhesions act as anchorage sites for vimentin filaments, with plectin isoform 1f being the crucial linker protein. Plectin serves as a nucleation and assembly center for the de novo formation of vimentin networks. Anchored vimentin creates a resilient cage-like core structure that affects cell shape
Total Intermittent Pringle Maneuver during Liver Resection Can Induce Intestinal Epithelial Cell Damage and Endotoxemia
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110009.pdf (publisher's version ) (Open Access)OBJECTIVES: The intermittent Pringle maneuver (IPM) is frequently applied to minimize blood loss during liver transection. Clamping the hepatoduodenal ligament blocks the hepatic inflow, which leads to a non circulating (hepato)splanchnic outflow. Also, IPM blocks the mesenteric venous drainage (as well as the splenic drainage) with raising pressure in the microvascular network of the intestinal structures. It is unknown whether the IPM is harmful to the gut. The aim was to investigate intestinal epithelial cell damage reflected by circulating intestinal fatty acid binding protein levels (I-FABP) in patients undergoing liver resection with IPM. METHODS: Patients who underwent liver surgery received total IPM (total-IPM) or selective IPM (sel-IPM). A selective IPM was performed by selectively clamping the right portal pedicle. Patients without IPM served as controls (no-IPM). Arterial blood samples were taken immediately after incision, ischemia and reperfusion of the liver, transection, 8 hours after start of surgery and on the first post-operative day. RESULTS: 24 patients (13 males) were included. 7 patients received cycles of 15 minutes and 5 patients received cycles of 30 minutes of hepatic inflow occlusion. 6 patients received cycles of 15 minutes selective hepatic occlusion and 6 patients underwent surgery without inflow occlusion. Application of total-IPM resulted in a significant increase in I-FABP 8 hours after start of surgery compared to baseline (p<0.005). In the no-IPM group and sel-IPM group no significant increase in I-FABP at any time point compared to baseline was observed. CONCLUSION: Total-IPM in patients undergoing liver resection is associated with a substantial increase in arterial I-FABP, pointing to intestinal epithelial injury during liver surgery. TRIAL REGISTRATION: ClinicalTrials.gov NCT01099475
Structural basis of the filamin A actin-binding domain interaction with F-actin
Cryo-EM reconstructions were deposited in the Electron Microscopy Data Bank with the following accession numbers: F20-F-actin-FLNaABD, EMD-7833; F20-F-actin-FLNaABD-Q170P, EMD-7832; F20-F-actin-FLNaABD-E254K, EMD-8918; Krios-F-actin-FLNaABD-E254K, EMD-7831. The corresponding FLNaABD-E254K filament model was deposited in the PDB with accession number 6D8C. Source data for F-actin-targeting analyses (Figs. 2c,d,g,h, 3b,c,e,f, 4d,e, 5c,d, and 6a,b) and co-sedimentation assays (Figs. 5g and 6d) are available with the paper online. Other data are available from the corresponding author upon reasonable request. We thank Z. Razinia for generating numerous FLNa constructs, S. Wu for expertise in using the Krios microscope, J. Lees for advice on model refinement, and M. Lemmon for helpful comments in preparing the manuscript. We also thank the Yale Center for Research Computing for guidance and use of the Farnam Cluster, as well as the staff at the YMS Center for Molecular Imaging for the use of the EM Core Facility. This work was funded by grants from the National Institutes of Health (R01-GM068600 (D.A.C.), R01-NS093704 (D.A.C.), R37-GM057247 (C.V.S.), R01-GM110530 (C.V.S.), T32-GM007324, T32-GM008283) and an award from American Heart Association (15PRE25700119 (D.V.I.)).Peer reviewedPostprin
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