WorldWideScience

Sample records for activities addressing valve

  1. Recent NRC research activities addressing valve and pump issues

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, D.L.

    1996-12-01

    The mission of the U.S. Nuclear Regulatory Commission (NRC) is to ensure the safe design, construction, and operation of commercial nuclear power plants and other facilities in the U.S.A. One of the main roles that the Office of Nuclear Regulatory Research (RES) plays in achieving the NRC mission is to plan, recommend, and implement research programs that address safety and technical issues deemed important by the NRC. The results of the research activities provide the bases for developing NRC positions or decisions on these issues. Also, RES performs confirmatory research for developing the basis to evaluate industry responses and positions on various regulatory requirements. This presentation summarizes some recent RES supported research activities that have addressed safety and technical issues related to valves and pumps. These activities include the efforts on determining valve and motor-operator responses under dynamic loads and pressure locking events, evaluation of monitoring equipment, and methods for detecting and trending aging of check valves and pumps. The role that RES is expected to play in future years to fulfill the NRC mission is also discussed.

  2. An electrochemical active valve

    NARCIS (Netherlands)

    Neagu, C.R.; Gardeniers, J.G.E.; Elwenspoek, M.; Kelly, J.J.

    1997-01-01

    A novel electrochemical microactuator was developed, which operates as an active valve. The microactuator consists of an electrochemical cell and a membrane that deflects because of the pressure of oxygen gas generated by electrolysis. Relatively large pressures (up to tens of bars) can be reached w

  3. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  4. Are valve repairs associated with better outcomes than replacements in patients with native active valve endocarditis?

    Science.gov (United States)

    Zhao, Dong; Zhang, Benqing

    2014-12-01

    A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether valve replacement was associated with higher morbidity and mortality rates than valve repair in patients with native active valve endocarditis. Altogether 662 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Traditionally, valve replacement has been the standard therapy for valve endocarditis when surgical treatment is indicated. But now valve repair is increasingly used as an alternative, which may avoid disadvantages of anticoagulation, lower the risk of prosthetic infection and improve postoperative survival. To compare outcomes of these two treatments between studies can be difficult because most of related papers contain raw data on prosthetic valve endocarditis or healed endocarditis, which were excluded from our manuscript. Studies only analysing the outcomes of either of these treatments without the comparison of valve repair and replacement were also excluded. Finally, seven papers were identified. The American Heart Association/American College of Cardiology 2006 valvular guidelines recommended that mitral valve repair should be performed instead of replacement when at all possible. In three of the seven studies, there were significant differences between valve repair and replacement in long-term survival. One study found that aortic valve repair offered better outcomes in freedom from reoperation at 5 years (P = 0.021) and in survival at 4 years (repair vs replacement 88 vs 65%; P = 0.047). One study reported that there was improved event-free survival at 10 years in the mitral valve repair group (P = 0.015), although there was more previous septic embolization in this group. In one study, early and late mortality

  5. AN ACTIVE VALVE WITH A CLAMPED MEMBRANE

    DEFF Research Database (Denmark)

    2009-01-01

    An active valve for use e.g. in fluidic microsystems is provided, wherein the active valve comprises a membrane having at least one flow gate, arranged between a first and a second substantially rigid element. Adjusting means provides an adjustment of the clamping force on membrane arranged between...... the first and second substantially rigid element. Hereby the flow rate through the active valve can be continuously and precisely controlled....

  6. [Easy and reproducible technique to address tricuspid valve regurgitation with patch augmentation.

    Science.gov (United States)

    Solinas, Marco; Bianchi, Giacomo; Glauber, Mattia

    2013-11-01

    We describe a patch augmentation of the anterior leaflet of the tricuspid valve to address tricuspid valve regurgitation due to leaflet retraction. The area of the anterior leaflet is measured using a tricuspid valve annuloplasty sizer; a glutaraldehyde-fixed autologous pericardial patch is trimmed with slight 5 mm oversize. The anterior leaflet is detached and the patch is sutured with three 5/0 running interlocked sutures, then an annuloplasty is performed with an undersized ring. This technique offers an easy and reproducible tool to address tricuspid regurgitation due to lack of leaflet coaptation.

  7. [Redo Aortic and Mitral Valve Replacement by Manouguian's Procedure for Active Prosthetic Valve Infection].

    Science.gov (United States)

    Kunitomo, Ryuji; Okamoto, Ken; Moriyama, Shuji; Sakaguchi, Hisashi; Tazume, Hirokazu; Yoshinaga, Takashi; Kawasuji, Michio

    2016-03-01

    The damage to the intervalvular fibrous trigone (IVFT) by infective endocarditis makes combined aortic and mitral valve replacement difficult. We performed Manouguian's double valve replacement for such a case and obtained a good result. A 81-year-old male underwent emergency operation due to active prosthetic valve endocarditis. He had a history of receiving combined aortic and mitral valve replacement because of active infective endocarditis at the age of 74 and redo aortic valve replacement 3 years after that. The infectious lesion extended from the mitral annulus to the IVFT and the aortic annulus, and it caused the prosthetic valve detachment from the aortic annulus. Manouguian's double valve replacement was required for radical resection and reconstruction of the IVFT. No recurrent infection or paravalvular leakage was observed during 49months follow up period. Manouguian's procedure is useful for complete resection of the infected IVFT and makes combined aortic and mitral valve replacement safer.

  8. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the...

  9. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the operational...

  10. Physical activity increases survival after heart valve surgery

    DEFF Research Database (Denmark)

    Lund, K.; Sibilitz, Kirstine Lærum; Kikkenborg berg, Selina;

    2016-01-01

    OBJECTIVES: Increased physical activity predicts survival and reduces risk of readmission in patients with coronary heart disease. However, few data show how physical activity is associated with survival and readmission after heart valve surgery. Objective were to assess the association between...... physical activity levels 6-12 months after heart valve surgery and (1) survival, (2) hospital readmission 18-24 months after surgery and (3) participation in exercise-based cardiac rehabilitation. METHODS: Prospective cohort study with registry data from The CopenHeart survey, The Danish National Patient...... of physical activity after heart valve surgery are positively associated with higher survival rates and participation in cardiac rehabilitation....

  11. Optically addressable single-use microfluidic valves by laser printer lithography.

    Science.gov (United States)

    Garcia-Cordero, Jose L; Kurzbuch, Dirk; Benito-Lopez, Fernando; Diamond, Dermot; Lee, Luke P; Ricco, Antonio J

    2010-10-21

    We report the design, fabrication, and characterization of practical microfluidic valves fabricated using laser printer lithography. These optofluidic valves are opened by directing optical energy from a solid-state laser, with similar power characteristics to those used in CD/DVD drives, to a spot of printed toner where localized heating melts an orifice in the polymer layer in as little as 500 ms, connecting previously isolated fluidic components or compartments. Valve functionality, response time, and laser input energy dependence of orifice size are reported for cyclo-olefin polymer (COP) and polyethylene terephthalate (PET) films. Implementation of these optofluidic valves is demonstrated on pressure-driven and centrifugal microfluidic platforms. In addition, these "one-shot" valves comprise a continuous polymer film that hermetically isolates on-chip fluid volumes within fluidic devices using low-vapor-permeability materials; we confirmed this for a period of one month. The fabrication and integration of optofluidic valves are compatible with a range of polymer microfabrication technologies and should facilitate the development of fully integrated, reconfigurable, and automated lab-on-a-chip systems, particularly when reagents must be stored on chip for extended periods, e.g. for medical diagnostic devices, lab-on-a-chip synthetic systems, or hazardous biochemical analysis platforms.

  12. Industry activities to improve valve performance

    Energy Technology Data Exchange (ETDEWEB)

    Callaway, C.

    1996-12-01

    Motor-operated valve issues refuse to go away. For over a decade the industry and the NRC have been focusing extraordinary resources on assuring these special components operate when called upon. Now that industry has fixed the design deficiencies, it is focusing on assuring that they perform their safety function within the current licensing basis for the remainder of plant life. NEI supported the efforts by ASME to develop OMN-1 and was encouraged that the industry and the NRC worked together to develop risk and performance based approaches to maintain MOV performance.

  13. Platelet activation through a Bi-leaflet mechanical heart valve

    Science.gov (United States)

    Hedayat, Mohammadali; Borazjani, Iman

    2016-11-01

    Platelet activation is one of the major drawbacks of the Mechanical Heart Valves (MHVs) which can increase the risk of thrombus formation in patients. The platelet activation in MHVs can be due to the abnormal shear stress during the systole, the backward leakage flow during the diastole, and the flow through the hinge region. We investigate the contribution of each of the above mechanism to the activation of platelets in MHVs by performing simulations of the flow through the MHV and in the hinge region. The large scale heart valve simulations are performed in a straight aorta using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm under physiological flow conditions. In addition, in order to perform the simulation of hinge region the flow field boundary conditions are obtained from the largescale simulations during a whole cardiac cycle. In order to investigate the role of hinge flow on platelet activation in MHVs, a 23mm St. Jude Medical Regent valve hinge with three different gap sizes is tested along with different platelet activation models to ensure the consistency of our results with different activation models. We compare the platelet activation of the hinge region against the bulk of the flow during one cardiac cycle. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

  14. Addressing Superstitious Beliefs through Science Activities.

    Science.gov (United States)

    King, Ken

    1996-01-01

    Presents a classroom activity that tests students' parapsychological powers and can demonstrate a number of methods of science, including the processes of formulating a hypothesis and rigorously subjecting the hypothesis to testing. (DDR)

  15. The MEMOLED: Active addressing with passive driving

    NARCIS (Netherlands)

    Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de

    2011-01-01

    Passive or active matrix driving schemes in large displays are prone to high power consumption and cost, respectively. For signage applications such as large out-door displays with low refresh rates there is as yet no technological solution. Here the MEMOLED solution, an organic light-emitting diode

  16. The MEMOLED : Active Addressing with Passive Driving

    NARCIS (Netherlands)

    Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.

    2011-01-01

    Passive or active matrix driving schemes in large displays are prone to high power consumption and cost, respectively. For signage applications such as large outdoor displays with low refresh rates there is as yet no technological solution. Here the MEMOLED solution, an organic light-emitting diode

  17. Excess flow shutoff valve

    Energy Technology Data Exchange (ETDEWEB)

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  18. Diagnostic for two-mode variable valve activation device

    Energy Technology Data Exchange (ETDEWEB)

    Fedewa, Andrew M

    2014-01-07

    A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

  19. Three-dimentional simulation of flow-induced platelet activation in artificial heart valves

    Science.gov (United States)

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman

    2015-11-01

    Since the advent of heart valve, several valve types such as mechanical and bio-prosthetic valves have been designed. Mechanical Heart Valves (MHV) are durable but suffer from thromboembolic complications that caused by shear-induced platelet activation near the valve region. Bio-prosthetic Heart Valves (BHV) are known for better hemodynamics. However, they usually have a short average life time. Realistic simulations of heart valves in combination with platelet activation models can lead to a better understanding of the potential risk of thrombus formation in such devices. In this study, an Eulerian approach is developed to calculate the platelet activation in three-dimensional simulations of flow through MHV and BHV using a parallel overset-curvilinear immersed boundary technique. A curvilinear body-fitted grid is used for the flow simulation through the anatomic aorta, while the sharp-interface immersed boundary method is used for simulation of the Left Ventricle (LV) with prescribed motion. In addition, dynamics of valves were calculated numerically using under-relaxed strong-coupling algorithm. Finally, the platelet activation results for BMV and MHV are compared with each other.

  20. Effect of co-free valve on activity reduction in PWR

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, C.B.; Han, B.C.; Bum, J.S.; Hwang, I.S. [Department of Nuclear Engineering, Seoul National Univ. (Korea, Republic of); Lee, C.B. [Korea Atomic Energy Research Inst., Daejon (Korea, Republic of)

    2002-07-01

    Radioactive nuclei, such as {sup 68}Co and {sup 60}Co, deposited on out-of-core surfaces in a pressurized water reactor (PWR) primary coolant system, are major sources of occupational radiation exposure to plant maintenance personnel and act as costly impediment to prompt and effective repairs. Valve hardfacing alloys exposed to primary coolant are considered as one of the main Co sources. To evaluate the Co-free valve, such as NOREM 02 and Deloro 50, the candidates for the alternative to Stellite 6, in a simulated PWR primary condition, SNU corrosion test loop (SCOTL) was constructed. For gate valves hard-faced with made of NOREM 02 and Deloro 50 hot cycling tests were conducted for up to 2,000 on-off cycles with cold leak tests at 1,000 cycle interval. It was observed that the leak rate of NOREM 02 (Fe-base) did not satisfy the nuclear grade valve leak criteria. After 1000 cycles test, while there was no leakage in case of Deloro 50 (Ni-base). Also, Deloro 50 showed no leakage after 2000 cycles. To estimate the activity reduction effect, we modified CRUDSIM-MIT which modeled the effects of coolant chemistry on the crud transport and activity buildup in the primary system of PWR. In the new code, crud evaluation and assessment (CREAT), {sup 60}Co activity buildup prediction includes 1) Co-base valve replacement effect, 2) Co-base valve maintenance effect, and 3) control rod drive mechanism (CRDM) and main coolant pump (MCP) shaft contribution. CREAT predicted that the main contributor of Co activity buildup was the corrosion-induced release of Co from the steam generator (SG) tubing. With new SG's tubed with alloy 690, Korean Next Generation Reactor (APR-1400) is expected to have about 64% lower Co activity on SG surface. The use of all Co-free valves is expected to cut additional 8% of activity which is only marginal. (authors)

  1. Application of High-speed Solenoid Valve to the Semi-active Control of Landing Gear

    Institute of Scientific and Technical Information of China (English)

    Liu Hui; Gu Hongbin; Chen Dawei

    2008-01-01

    To select or develop an appropriate actuator is one of the key and difficult issues in the study of semi-active controlled landing gear.Performance of the actuator may directly affect the effectiveness of semi-active control.In this article,parallel high-speed solenoid valves are chosen to be the actuators for the semi-active controlled landing gear and being studied.A nonlinear high-speed solenoid valve model is developed with the consideration of magnctic saturation characteristics and verified by test.According to the design rule of keeping the peak load as small as possible while absorbing the specified shock energy,a fuzzy PD control rule is designed.By the rule,controller parameters can be self-regulated.The simulation results indicate that the semi-active control based on high-speed solenoid valve can effectively improve the control performance and reduce impact load during landing.

  2. Remote actuated valve implant

    Energy Technology Data Exchange (ETDEWEB)

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen

    2016-05-10

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  3. Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

    Science.gov (United States)

    Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

    2012-01-01

    At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

  4. Self-Rupturing Hermetic Valve

    Science.gov (United States)

    Tucker, Curtis E., Jr.; Sherrit, Stewart

    2011-01-01

    For commercial, military, and aerospace applications, low-cost, small, reliable, and lightweight gas and liquid hermetically sealed valves with post initiation on/off capability are highly desirable for pressurized systems. Applications include remote fire suppression, single-use system-pressurization systems, spacecraft propellant systems, and in situ instruments. Current pyrotechnic- activated rupture disk hermetic valves were designed for physically larger systems and are heavy and integrate poorly with portable equipment, aircraft, and small spacecraft and instrument systems. Additionally, current pyrotechnically activated systems impart high g-force shock loads to surrounding components and structures, which increase the risk of damage and can require additional mitigation. The disclosed mechanism addresses the need for producing a hermetically sealed micro-isolation valve for low and high pressure for commercial, aerospace, and spacecraft applications. High-precision electrical discharge machining (EDM) parts allow for the machining of mated parts with gaps less than a thousandth of an inch. These high-precision parts are used to support against pressure and extrusion, a thin hermetically welded diaphragm. This diaphragm ruptures from a pressure differential when the support is removed and/or when the plunger is forced against the diaphragm. With the addition of conventional seals to the plunger and a two-way actuator, a derivative of this design would allow nonhermetic use as an on/off or metering valve after the initial rupturing of the hermetic sealing disk. In addition, in a single-use hermetically sealed isolation valve, the valve can be activated without the use of potential leak-inducing valve body penetrations. One implementation of this technology is a high-pressure, high-flow-rate rupture valve that is self-rupturing, which is advantageous for high-pressure applications such as gas isolation valves. Once initiated, this technology is self

  5. Valve Disease

    Science.gov (United States)

    ... heart valves, valve insufficiency, valve regurgitation, valve stenosis, valvular heart disease Every time your heart beats, blood flows into, ... removed from the market after being linked to heart valve disease. An infection in the lining of the heart's ...

  6. EPRI activities to address reactor pressure vessel integrity issues

    Energy Technology Data Exchange (ETDEWEB)

    Rosinski, S.T.; Carter, R.G. [Electric Power Res. Inst., Charlotte, NC (United States)

    1999-12-01

    The demonstration of reactor pressure vessel (RPV) structural integrity is an essential element in ensuring the continued safe and reliable operation of US nuclear power plants. The Electric Power Research Institute (EPRI), through its domestic and international member utilities, continues to pursue an aggressive research program to develop technologies and capabilities that will address issues associated with reactor pressure vessel integrity. Ongoing research in the EPRI nuclear power group materials performance program covers a broad range of technical areas associated with RPVs. The program is structured under the following product groups; (1) management and mitigation; (2) material performance databases; (3) material condition assessment; and (4) operability assessment. Specific activities under each of theses product groups are described in this paper. (orig.)

  7. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Kalyani Nair; C V Muraleedharan; G S Bhuvaneshwar

    2003-06-01

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the performance of mechanical heart valves. The clinical performance of mechanical heart valves is also addressed. Efforts made in India in the development of mechanical heart valves are also discussed.

  8. Assessment of Severe Accident Depressurization Valve Activation Strategy for Chinese Improved 1000 MWe PWR

    Directory of Open Access Journals (Sweden)

    Ge Shao

    2013-01-01

    Full Text Available To prevent HPME and DCH, SADV is proposed to be added to the pressurizer for Chinese improved 1000 MWe PWR NPP with the reference of EPR design. Rapid depressurization capability is assessed using the mechanical analytical code. Three typical severe accident sequences of TMLB’, SBLOCA, and LOFW are selected. It shows that with activation of the SADV the RCS pressure is low enough to prevent HPME and DCH. Natural circulation at upper RPV and hot leg is considered for the rapid depressurization capacity analysis. The result shows that natural circulation phenomenon results in heat transfer from the core to the pipes in RCS which may cause the creep rupture of pipes in RCS and delays the severe accident progression. Different SADV valve areas are investigated to the influence of depressurization of RCS. Analysis shows that the introduction of SADV with right valve area will delay progression of core degradation to RPV failure. Valve area is to be optimized since smaller SADV area will reduce its effect and too large valve area will lead to excessive loss of water inventory in RCS and makes core degradation progression to RPV failure faster without additional core cooling water sources.

  9. Addressing security issues related to virtual institute distributed activities

    Science.gov (United States)

    Stytz, Martin R.; Banks, Sheila B.

    2008-03-01

    One issue confounding the development and experimentation of distributed modeling and simulation environments is the inability of the project team to identify and collaborate with resources, both human and technical, from outside the United States. This limitation is especially significant within the human behavior representation area where areas such as cultural effects research and joint command team behavior modeling require the participation of various cultural and national representatives. To address this limitation, as well as other human behavior representation research issues, NATO Research and Technology Organization initiated a project to develop a NATO virtual institute that enables more effective and more collaborative research into human behavior representation. However, in building and operating a virtual institute one of the chief concerns must be the cyber security of the institute. Because the institute "exists" in cyberspace, all of its activities are susceptible to cyberattacks, subterfuge, denial of service and all of the vulnerabilities that networked computers must face. In our opinion, for the concept of virtual institutes to be successful and useful, their operations and services must be protected from the threats in the cyber environment. A key to developing the required protection is the development and promulgation of standards for cyber security. In this paper, we discuss the types of cyber standards that are required, how new internet technologies can be exploited and can benefit the promulgation, development, maintenance, and robustness of the standards. This paper is organized as follows. Section One introduces the concept of the virtual institutes, the expected benefits, and the motivation for our research and for research in this area. Section Two presents background material and a discussion of topics related to VIs, uman behavior and cultural modeling, and network-centric warfare. Section Three contains a discussion of the

  10. Active and Precise Control of Microdroplet Division Using Horizontal Pneumatic Valves in Bifurcating Microchannel

    Directory of Open Access Journals (Sweden)

    Shuichi Shoji

    2013-05-01

    Full Text Available This paper presents a microfluidic system for the active and precise control of microdroplet division in a micro device. Using two horizontal pneumatic valves formed at downstream of bifurcating microchannel, flow resistances of downstream channels were variably controlled. With the resistance control, volumetric ratio of downstream flows was changed and water-in-oil microdroplets were divided into two daughter droplets of different volume corresponding to the ratio. The microfluidic channels and pneumatic valves were fabricated by single-step soft lithography process of PDMS (polydimethylsiloxane using SU-8 mold. A wide range control of the daughter droplets’ volume ratio was achieved by the simple channel structure. Volumetric ratio between large and small daughter droplets are ranged from 1 to 70, and the smallest droplet volume of 14 pL was obtained. The proposed microfluidic device is applicable for precise and high throughput droplet based digital synthesis.

  11. Promoting Physical Activity: Addressing Barriers and Moving Forward

    Science.gov (United States)

    Beighle, Aaron; Morrow, James R.

    2014-01-01

    The barriers that keep individuals from adopting and maintaining active lifestyles are very complex. Strategies for overcoming these barriers and to incentivize and assist inactive individuals to benefit from physical activity are necessary. In addition, it is important to examine the impact of public policy on active living. As youth physical…

  12. Promoting Physical Activity: Addressing Barriers and Moving Forward

    Science.gov (United States)

    Beighle, Aaron; Morrow, James R.

    2014-01-01

    The barriers that keep individuals from adopting and maintaining active lifestyles are very complex. Strategies for overcoming these barriers and to incentivize and assist inactive individuals to benefit from physical activity are necessary. In addition, it is important to examine the impact of public policy on active living. As youth physical…

  13. Ultrasound-targeted transfection of tissue-type plasminogen activator gene carried by albumin nanoparticles to dog myocardium to prevent thrombosis after heart mechanical valve replacement

    Directory of Open Access Journals (Sweden)

    Ji J

    2012-06-01

    Full Text Available Ji Jun, Ji Shang-Yi, Yang Jian-An, He Xia, Yang Xiao-Han, Ling Wen-Ping, Chen Xiao-LingDepartment of Pathology and Cardiovascular Surgery, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen, Guangdong, People's Republic of ChinaBackground: There are more than 300,000 prosthetic heart valve replacements each year worldwide. These patients are faced with a higher risk of thromboembolic events after heart valve surgery and long-term or even life-long anticoagulative and antiplatelet therapies are necessary. Some severe complications such as hemorrhaging or rebound thrombosis can occur when the therapy ceases. Tissue-type plasminogen activator (t-PA is a thrombolytic agent. One of the best strategies is gene therapy, which offers a local high expression of t-PA over a prolonged time period to avoid both systemic hemorrhaging and local rebound thrombosis. There are some issues with t-PA that need to be addressed: currently, there is no up-to-date report on how the t-PA gene targets the heart in vivo and the gene vector for t-PA needs to be determined.Aims: To fabricate an albumin nano-t-PA gene ultrasound-targeted agent and investigate its targeting effect on prevention of thrombosis after heart mechanic valve replacement under therapeutic ultrasound.Methods: A dog model of mechanical tricuspid valve replacement was constructed. A highly expressive t-PA gene plasmid was constructed and packaged by nanoparticles prepared with bovine serum albumin. This nanopackaged t-PA gene plasmid was further cross-linked to ultrasonic microbubbles prepared with sucrose and bovine serum albumin to form the ultrasonic-targeted agent for t-PA gene transfection. The agent was given intravenously followed by a therapeutic ultrasound treatment (1 MHz, 1.5 w/cm2, 10 minutes of the heart soon after valve replacement had been performed. The expression of t-PA in myocardium was detected with multiclonal antibodies to t-PA by the indirect immunohistochemical method

  14. Safety/relief-valve test program

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, J.A.

    1982-01-01

    In response to the NRC's Task 2.1.2 following the TMI-2 accident, government and industry programs were formulated to address the performance of safety and relief valve systems for pressurized and boiling water reactors. Objective is to demonstrate by testing and analysis that safety and relief valve systems in the reactor coolant system are qualified for the anticipated full range of reactor operating and accident conditions. The EPRI PWR program tested PWR safety valves and power operated relief valves (PORVs) under steam, liquid, and steam/liquid transition conditions. The program also tested PWR PORV block valves under steam conditions. The GE BWR program tested BWR relief and safety/relief valves under high pressure steam and low pressure liquid conditions. EG and G Idaho recent activities have focused on the evaluation of the industry test data, evaluation and modification of analytical codes for safety/relief valve system analysis, and initial evaluation of utility responses to US NRC program requirements.

  15. Actively addressed single pixel full-colour plasmonic display

    Science.gov (United States)

    Franklin, Daniel; Frank, Russell; Wu, Shin-Tson; Chanda, Debashis

    2017-05-01

    Dynamic, colour-changing surfaces have many applications including displays, wearables and active camouflage. Plasmonic nanostructures can fill this role by having the advantages of ultra-small pixels, high reflectivity and post-fabrication tuning through control of the surrounding media. However, previous reports of post-fabrication tuning have yet to cover a full red-green-blue (RGB) colour basis set with a single nanostructure of singular dimensions. Here, we report a method which greatly advances this tuning and demonstrates a liquid crystal-plasmonic system that covers the full RGB colour basis set, only as a function of voltage. This is accomplished through a surface morphology-induced, polarization-dependent plasmonic resonance and a combination of bulk and surface liquid crystal effects that manifest at different voltages. We further demonstrate the system's compatibility with existing LCD technology by integrating it with a commercially available thin-film-transistor array. The imprinted surface interfaces readily with computers to display images as well as video.

  16. Strategies to Address Common Challenges When Teaching in an Active Learning Classroom

    Science.gov (United States)

    Petersen, Christina I.; Gorman, Kristen S.

    2014-01-01

    This chapter provides practical strategies for addressing common challenges that arise for teachers in active learning classrooms. Our strategies come from instructors with experience teaching in these environments.

  17. Strategies to Address Common Challenges When Teaching in an Active Learning Classroom

    Science.gov (United States)

    Petersen, Christina I.; Gorman, Kristen S.

    2014-01-01

    This chapter provides practical strategies for addressing common challenges that arise for teachers in active learning classrooms. Our strategies come from instructors with experience teaching in these environments.

  18. Successful thrombolysis of a thrombosed prosthetic mitral valve using a synthetic tissue plasminogen activator: a case report

    Directory of Open Access Journals (Sweden)

    Al-Fadhli Jamal

    2010-08-01

    Full Text Available Abstract Introduction Prosthetic valve thrombosis is a rare but life-threatening condition that requires careful evaluation and prompt treatment. While surgical intervention remains the gold standard, thrombolytic therapy is now emerging as a potential substitute. Various thrombolytic treatments including streptokinase, urokinase and recombinant tissue plasminogen activators have been reported with variable success rates. However, the data on the use of tenecteplase (a synthetic tissue plasminogen activator is limited. Case presentation A 44-year-old Middle Eastern man with a previously implanted prosthetic mitral valve presented with exertional dyspnea and orthopnea. Investigations revealed a thrombosed prosthetic mitral valve. Successful thrombolysis was achieved using tenecteplase which lead to the complete restoration of valve function with no risk to the patient. Conclusion Prosthetic valve thrombosis is a rare but life threatening condition, the diagnosis of which requires a high index of suspicion. Tenecteplase can be used successfully in the management of such cases. It has proved to be useful with no extra risk to the patient.

  19. Study of prognostic significance of antenatal ultrasonography and renin angiotensin system activation in predicting disease severity in posterior urethral valves

    Directory of Open Access Journals (Sweden)

    Divya Bhadoo

    2015-01-01

    Full Text Available Aims: Study on prognostic significance of antenatal ultrasonography and renin angiotensin system activation in predicting disease severity in posterior urethral valves. Materials and Methods: Antenatally diagnosed hydronephrosis patients were included. Postnatally, they were divided into two groups, posterior urethral valve (PUV and non-PUV. The studied parameters were: Gestational age at detection, surgical intervention, ultrasound findings, cord blood and follow up plasma renin activity (PRA values, vesico-ureteric reflux (VUR, renal scars, and glomerular filtration rate (GFR. Results: A total of 25 patients were included, 10 PUV and 15 non-PUV. All infants with PUV underwent primary valve incision. GFR was less than 60 ml/min/1.73 m 2 body surface area in 4 patients at last follow-up. Keyhole sign, oligoamnios, absent bladder cycling, and cortical cysts were not consistent findings on antenatal ultrasound in PUV. Cord blood PRA was significantly higher (P < 0.0001 in PUV compared to non-PUV patients. Gestational age at detection of hydronephrosis, cortical cysts, bladder wall thickness, and amniotic fluid index were not significantly correlated with GFR while PRA could differentiate between poor and better prognosis cases with PUV. Conclusions: Ultrasound was neither uniformly useful in diagnosing PUV antenatally, nor differentiating it from cases with non-PUV hydronephrosis. In congenital hydronephrosis, cord blood PRA was significantly higher in cases with PUV compared to non-PUV cases and fell significantly after valve ablation. Cord blood PRA could distinguish between poor and better prognosis cases with PUV.

  20. Implantation of the CoreValve percutaneous aortic valve.

    Science.gov (United States)

    Lamarche, Yoan; Cartier, Raymond; Denault, André Y; Basmadjian, Arsène; Berry, Colin; Laborde, Jean-Claude; Bonan, Raoul

    2007-01-01

    Surgical aortic valve replacement is the only recommended treatment for significant aortic valve stenosis. Percutaneous aortic valve replacement appears to be a novel option for high-risk patients. We report the implantation of the ReValving system (CoreValve, Paris, France) in a 64-year-old woman who was refused aortic valve replacement surgery for critical aortic stenosis and left ventricular dysfunction because of severe pulmonary fibrosis. After anesthesia, the patient was put on femorofemoral cardiopulmonary bypass, and underwent a balloon valvuloplasty with subsequent retrograde aortic valve replacement by the ReValving system. Transesophageal echocardiographic monitoring of the patient's hemodynamics showed immediate improvements of the valvular area and left ventricular ejection fraction and only traces of paravalvular leaks. The patient was easily weaned from ventilation and resumed activity soon after the surgery. A multidisciplinary approach is presently necessary to offer a reliable and safe procedure.

  1. [Dehiscence of the Pericardial Patch, after Surgical Treatment of Active Infective Aortic Valve Endocarditis with Reconstruction of the Aortic Annulus Using a Glutaraldehyde-treated Autologous Pericardium].

    Science.gov (United States)

    Yoshida, Kazufumi; Fukunaga, Naoto; Koizumi, Shigeki; Nishiya, Kenta; Matsuda, Yasuhiro; Ishigami, Masanosuke; Nagasawa, Atsushi; Sakata, Ryuzo; Koyama, Tadaaki

    2017-03-01

    A 50-year-old man was admitted with fever and chill sensation 6 months ago. Transthoracic echocardiography (TTE) showed left and right coronary cusp prolapses and a thickened tissue of the aortic curtain. Congestive heart failure due to active infective aortic valve endocarditis was diagnosed, and he underwent aortic valve replacement. The aortic annulus was reconstructed using a glutaraldehydetreated autologous pericardium. Six months after surgery, TTE showed severe aortic regurgitation and saccular change in the aortic annulus. Transesophageal echocargiography showed some echo free space from left to noncoronary cusp and abnormal movement of the prosthetic valve annulus. Intraoperative examination showed dehiscence of the pericardial patch from the aortic wall, but no finding of infection. Aortic valve rereplacement was performed with reconstruction of the aortic annulus using a bovine pericardium. To prevent the dehiscence of the pericardial patch from the aortic wall, sutures fixing the prosthetic valve were passed from outside of the aortic wall.

  2. Examining How Web Designers' Activity Systems Address Accessibility: Activity Theory as a Guide

    Science.gov (United States)

    Russell, Kyle

    2014-01-01

    While accessibility of information technologies is often acknowledged as important, it is frequently not well addressed in practice. The purpose of this study was to examine the work of web developers and content managers to explore why and how accessibility is or is not addressed as an objective as websites are planned, built and maintained.…

  3. Plasma renin activity: An early marker of progressive renal disease in posterior urethral valves

    Directory of Open Access Journals (Sweden)

    Minu Bajpai

    2013-01-01

    Full Text Available Introduction: A significant number of children with posterior urethral valves (PUV develop chronic renal failure (CRF due to activation of the renin angiotensin system (RAS. We investigated the role of plasma renin activity (PRA in these cases and sought to establish a relationship between the accepted criteria of renal damage and PRA. Aims and Objectives: The aim of this study is to establish the relationship between PRA and CRF. Materials and Methods: The records of 250 patients with PUV were reviewed. Multiple linear regression analysis was used to assess correlations between PRA, grade of reflux, presence of scars and raised creatinine and decrease in glomerular filtration rates (GFR. A P < 0.5 was considered as significant. Results: A total of 58 patients were included. Their mean age was 16 years, range 5.3-24.2 years, mean follow-up period was 12.6 ± 3.6 years. At diagnosis, 22/58 (38% patients were in CRF and 36/58 (62% patients had normal renal function (RF. The mean PRA after treatment was higher in those who developed CRF than in those with normal RF (12.6 ± 10.2 vs. 34.6 ± 14.2 ng/ml/24 h, P = 0.02. Mean GFR at 1 year of age were 48 ± 9.8 ml/min/1.73 m 2 and 86 ± 12.5 ml/min/1.73 m 2 respectively (P = 0.005. PRA correlated negatively with GFR, t = -2.816, Confidence Interval: P = 0. 007. In the temporal plot over a period of 14 years, a rise in PRA preceded the fall in GFR in patients who developed CRF. Conclusions: This study shows that RAS is activated earlier in kidneys susceptible to damage. PRA could be investigated as a marker for the early detection and prevention of ongoing renal damage.

  4. 76 FR 14413 - Risk Mitigation Strategies To Address Potential Procoagulant Activity in Immune Globulin...

    Science.gov (United States)

    2011-03-16

    ...) pathophysiology of arterial and venous thrombosis in this context; (3) research to identify specific procoagulant...) the role of activated Coagulation Factor XIa in IGIV-associated thrombosis; (6) test methods for... HUMAN SERVICES Food and Drug Administration Risk Mitigation Strategies To Address Potential...

  5. Percutaneous mitral valve repair.

    Science.gov (United States)

    Gillinov, A Marc; Liddicoat, John R

    2006-01-01

    Surgical mitral valve repair is the procedure of choice to treat mitral regurgitation of all etiologies. Whereas annuloplasty is the cornerstone of mitral valve repair, a variety of other surgical techniques are utilized to correct dysfunction of the leaflets and subvalvular apparatus; in most cases, surgical repair entails application of multiple repair techniques in each patient. Preclinical studies and early human experience have demonstrated that some of these surgical repair techniques can be performed using percutaneous approaches. Specifically, there has been great progress in the development of novel technology to facilitate percutaneous annuloplasty and percutaneous edge-to-edge repair. The objectives of this report were to (1) discuss the surgical foundations for these percutaneous approaches; (2) review device design and experimental and clinical results of percutaneous valve repair; and (3) address future directions, including the key challenges of patient selection and clinical trial design.

  6. Pressure locking and thermal binding of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, E.M.

    1996-12-01

    Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

  7. Bicuspid aortic valve: a literature review and its impact on sport activity.

    Science.gov (United States)

    De Mozzi, Paola; Longo, Umile Giuseppe; Galanti, Giorgio; Maffulli, Nicola

    2008-01-01

    The bicuspid aortic valve (BAV) is the most common congenital cardiac malformation. A literature search was performed using the key words 'bicuspid aortic valve', 'pathophysiology', 'exercise' and 'training'. BAV is the result of a complex developmental process where several genes seem to lead to abnormal valvulogenesis. Complications associated with BAV include aortic stenosis (AS) and regurgitation, infective endocarditis and aortic dilation and dissection. Moreover, BAV may be associated with other cardiovascular anomalies, mainly aortic coarctation. There is greater awareness of BAV in the young population who practice sport, with an increasing interest on the impact of regular and competitive exercise on athletes with BAV. The early identification of BAV through pre-participation screening is of paramount importance, and the justification of the more appropriate diagnostic methods is still an area of debate. A normally functioning BAV usually does not represent a limit for practising sport. The stress of regular and intense exercise on an abnormal aortic valve may favour its early deterioration and accelerate the development of complications. Therefore, athletes with BAV warrant regular follow-up, which should include echocardiographic assessment at least every year. The eligibility for participation and ability to continue to practise competitive sports in athletes with BAV cannot be generalized, but needs to be individualized depending on age, severity of lesions and type of sport. Further studies are required to elucidate the impact of physical training and competitive sports on the natural course of the BAV.

  8. Valve's Way

    Directory of Open Access Journals (Sweden)

    Phanish Puranam

    2015-06-01

    Full Text Available What can we learn from outliers? While statisticians rightly warn us against their non-representativeness, we believe it is also true that thinking carefully about what makes them atypical may improve our understanding of the typical case. This is the premise behind the Organization Zoo series. Valve Corporation (Valve is an unusual firm. It is a rare example of a firm that appears to operate without any formal hierarchy in its organization. What can we learn about the viability of authority hierarchies from Valve’s way of organizing? We wrote a brief account of Valve based on public information sources and asked several renowned organizational experts to comment on this unusual firm. We asked them to write a short commentary on what the Valve example means for organizational theorists and practitioners. Thankfully, they all accepted, and we are excited to present the results of their thinking in this first “exhibit” in the Organization Zoo.

  9. Cardiac Tamponade following Mitral Valve Replacement for Active Infective Endocarditis with Ring Abscess

    Directory of Open Access Journals (Sweden)

    R. Ranjan

    2015-01-01

    Full Text Available Periannular extension and abscess formation are rare but deadly complications of infective endocarditis (IE with high mortality. Multimodality cardiac imaging, invasive and noninvasive, is needed to accurately define the extent of the disease. Debridement, reconstruction, and valve replacement, often performed in an emergent setting, remain the treatment of choice. Here we present a case of severe IE in a 29-year-old intravenous drug user who after undergoing debridement of the abscess, annular reconstruction, and mitral valve replacement (MVR presented with recurrence of shortness of breath and pedal edema. Transthoracic echocardiogram (TTE showed a 6.2×5.5 cm cavity, posterior to and communicating with the left ventricle through a 3 cm wide fistulous opening, in proximity of the reconstructed mitral annulus. The patient underwent a redo MVR with patch closure of the fistulous opening, with good clinical outcome. This case highlights the classic TTE findings and the necessity for close follow-up in the perioperative period in patients undergoing surgery for periannular extension of infection. A cardiac magnetic resonance imaging can be considered, preoperatively, in such cases to identify the extent of myocardial involvement and surgical planning.

  10. POST-LAUNCHING MONITORING ACTIVITIES FOR NEW TRANSACTIONAL BANKING PRODUCTS ADDRESSED TO SMES (CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    Giuca Simona-Mihaela

    2014-07-01

    Full Text Available The current paper has the aim to provide guidelines for post-launching monitoring activities and steps related to new transactional banking products addressed to SMEs. While the pre-launching activities have the purpose of accurately defining the objectives, assumptions and estimations, the purpose of the post-launching plan is to identify: if the final objectives of a product launching have been met, on one hand, to analyze results in the sense of identifying an efficient action plan in order to overcome the lack of results (if case, but most important, to identify opportunities for optimizing the products and for communicating properly the value proposition. This paper also presents schemes for monitoring the results from a business case and for motivating the sales force, as an essential step in increasing the sales. Therefore, alternatives of incentive campaigns are presented, as sustainable campaigns with to purpose to achieve an expected success rate. As an additional support guideline for the sales force, some scenarios and post-sales actions are presented, together with an example of portfolio analysis considering potential per client. Considering the methods and details presented in the current paper, one can identify the importance and find out how to monitor the results after launching a new transactional product addressed to SMEs, can understand and design an incentive scheme and also define actions to be taken in order to increase revenues from a newly launched transactional product.

  11. Addressing the challenges of GRACE application in basins with hydraulic fracturing activity

    Science.gov (United States)

    Read, L.; Ruybal, C.; Hogue, T. S.; Hinojosa, M. P.

    2016-12-01

    Despite the growing number of studies that employ GRACE to quantify groundwater resources we have found no published studies on whether GRACE is also accounting for subsurface mass redistributions related to energy development activities from oil production, water production, and wastewater injection. Given the similar densities of water and crude oil (water is 1.0g/cc, crude oil is 0.8-0.9g/cc) and the fact that large volumes of oil and water are extracted on a monthly basis for hydraulic fracturing or reinjected as a means of waste disposal, it is important to determine whether GRACE is detecting mass redistributions from energy development to be able to correctly infer changes in water mass. The purpose of this study is to investigate whether GRACE measurements are impacted by energy development activities and offer a methodology for determining whether this activity should be considered when evaluating changes in terrestrial water storage, groundwater storage, or any other prediction involving quantification of groundwater. To address this question we compiled a dataset from the Bakken Play in North Dakota to use as a case study, where oil production was significant and increased exponentially from 2002-2015, and groundwater withdrawals for agriculture were relatively stable and limited. Preliminary results indicate that oil and gas production is of a similar scale and thus important to include when calculating groundwater changes. Broadly, this research addresses the challenges and uncertainties in applying GRACE to quantify groundwater or terrestrial water changes in energy-active basins, namely in accounting for oil reservoir changes, production, and injection rates, as well as the process of data collection in proprietary systems.

  12. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  13. Analysis of Complex Valve and Feed Systems

    Science.gov (United States)

    Ahuja, Vineet; Hosangadi, Ashvin; Shipman, Jeremy; Cavallo, Peter; Dash, Sanford

    2007-01-01

    A numerical framework for analysis of complex valve systems supports testing of propulsive systems by simulating key valve and control system components in the test loop. In particular, it is designed to enhance the analysis capability in terms of identifying system transients and quantifying the valve response to these transients. This system has analysis capability for simulating valve motion in complex systems operating in diverse flow regimes ranging from compressible gases to cryogenic liquids. A key feature is the hybrid, unstructured framework with sub-models for grid movement and phase change including cryogenic cavitations. The multi-element unstructured framework offers improved predictions of valve performance characteristics under steady conditions for structurally complex valves such as pressure regulator valve. Unsteady simulations of valve motion using this computational approach have been carried out for various valves in operation at Stennis Space Center such as the split-body valve and the 10-in. (approx.25.4-cm) LOX (liquid oxygen) valve and the 4-in. (approx.10 cm) Y-pattern valve (liquid nitrogen). Such simulations make use of variable grid topologies, thereby permitting solution accuracy and resolving important flow physics in the seat region of the moving valve. An advantage to this software includes possible reduction in testing costs incurred due to disruptions relating to unexpected flow transients or functioning of valve/flow control systems. Prediction of the flow anomalies leading to system vibrations, flow resonance, and valve stall can help in valve scheduling and significantly reduce the need for activation tests. This framework has been evaluated for its ability to predict performance metrics like flow coefficient for cavitating venturis and valve coefficient curves, and could be a valuable tool in predicting and understanding anomalous behavior of system components at rocket propulsion testing and design sites.

  14. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  15. [PROWESS, ENHANCE and ADDRESS: clinical implications for the treatment with drotrecogin alfa (activated)].

    Science.gov (United States)

    Cobas Meyer, M; Langenfeld, H; Rossaint, R; Sablotzki, A

    2006-06-01

    Drotrecogin alfa (activated) (DrotAA) represents a therapeutic advance in the treatment of severe sepsis. In the pivotal PROWESS trial DrotAA had demonstrated a significant decrease in 28-day mortality, most evident in the subgroup of patients at higher risk of death. Thus, DrotAA was licensed throughout Europe for treatment of adult patients with severe sepsis with multiple organ failure when added to best standard care. The ADDRESS trial was mandated by the FDA to investigate prospectively the treatment effect of DrotAA in patients at low risk of death, e.g. single organ failure. The trial was prematurely stopped due to futility, because no reduction in mortality was observed in this non-indicated patient population. The ENHANCE open-label trial enrolled similar patients to the PROWESS trial and the observed 28-day mortality was consistent with the results seen in the PROWESS trial. Survival rates for patients receiving DrotAA early within 24 h from the first sepsis-induced organ dysfunction were significantly higher than in patients treated later. In this overview we will discuss the results of the ENHANCE and ADDRESS trials in the context of the PROWESS study and clinical implications for the treatment with DrotAA.

  16. Closed bore XMR (CBXMR) systems for aortic valve replacement: Active magnetic shielding of x-ray tubes

    Energy Technology Data Exchange (ETDEWEB)

    Bracken, John A.; DeCrescenzo, Giovanni; Komljenovic, Philip; Lillaney, Prasheel V.; Fahrig, Rebecca; Rowlands, J. A. [Department of Medical Biophysics and Sunnybrook Health Sciences Center, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, Stanford University, Stanford, California 94305 (United States); Department of Medical Biophysics and Sunnybrook Health Sciences Center, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)

    2009-05-15

    Hybrid closed bore x-ray/MRI systems are being developed to improve the safety and efficacy of percutaneous aortic valve replacement procedures by harnessing the complementary strengths of the x-ray and MRI modalities in a single interventional suite without requiring patient transfer between two rooms. These systems are composed of an x-ray C-arm in close proximity ({approx_equal}1 m) to an MRI scanner. The MRI magnetic fringe field can cause the electron beam in the x-ray tube to deflect. The deflection causes the x-ray field of view to shift position on the detector receptacle. This could result in unnecessary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. Therefore, the electron beam deflection must be corrected. The authors developed an active magnetic shielding system that can correct for electron beam deflection to within an accuracy of 5% without truncating the field of view or increasing exposure to the patient. This system was able to automatically adjust to different field strengths as the external magnetic field acting on the x-ray tube was changed. Although a small torque was observed on the shielding coils of the active shielding system when they were placed in a magnetic field, this torque will not impact their performance if they are securely mounted on the x-ray tube and the C-arm. The heating of the coils of the shielding system for use in the clinic caused by electric current was found to be slow enough not to require a dedicated cooling system for one percutaneous aortic valve replacement procedure. However, a cooling system will be required if multiple procedures are performed in one session.

  17. Vacuum Valve

    CERN Multimedia

    1974-01-01

    This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.

  18. Valve's Way

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Dobrajska, Magdalena

    2015-01-01

    to what extent it represents a new blueprint for organization design, despite it being consistent with an “egalitarian Zeitgeist” (Puranam, 2014). In fact, managerial authority may be of increasing importance rather than the opposite (Guadalupe, Li, & Wulf, 2015). Thus, Valve is, and will remain...

  19. Valve's Way

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Dobrajska, Magdalena

    2015-01-01

    Puranam and Håkonsson (2015) challenge us to ponder what we as organization design theorists make of Valve’s way (see also Jeppesen, 2008). We believe that Valve, in spite of its radical vision, does not represent a challenge to fundamental organization design theory and that it is questionable...

  20. Addressing complex healthcare problems in diverse settings: insights from activity theory.

    Science.gov (United States)

    Greig, Gail; Entwistle, Vikki A; Beech, Nic

    2012-02-01

    In the U.K., approaches to policy implementation, service improvement and quality assurance treat policy, management and clinical care as separate, hierarchical domains. They are often based on the central knowledge transfer (KT) theory idea that best practice solutions to complex problems can be identified and 'rolled out' across organisations. When the designated 'best practice' is not implemented, this is interpreted as local--particularly management--failure. Remedial actions include reiterating policy aims and tightening performance management of solution implementation, frequently to no avail. We propose activity theory (AT) as an alternative approach to identifying and understanding the challenges of addressing complex healthcare problems across diverse settings. AT challenges the KT conceptual separations between levels of policy, management and clinical care. It does not regard knowledge and practice as separable, and does not understand them in the commodified way that has typified some versions of KT theory. Instead, AT focuses on "objects of activity" which can be contested. It sees new practice as emerging from contradiction and understands knowledge and practice as fundamentally entwined, not separate. From an AT perspective, there can be no single best practice. The contributions of AT are that it enables us to understand the dynamics of knowledge-practice in activities rather than between levels. It shows how efforts to reduce variation from best practice may paradoxically remove a key source of practice improvement. After explaining the principles of AT we illustrate its explanatory potential through an ethnographic study of primary healthcare teams responding to a policy aim of reducing inappropriate hospital admissions of older people by the 'best practice' of rapid response teams.

  1. A lab-on-a-disc with reversible and thermally stable diaphragm valves.

    Science.gov (United States)

    Kim, Tae-Hyeong; Sunkara, Vijaya; Park, Juhee; Kim, Chi-Ju; Woo, Hyun-Kyung; Cho, Yoon-Kyoung

    2016-10-01

    A lab-on-a-disc is a unique microfluidic platform that utilizes centrifugal force to pump liquids. This offers many benefits for point-of-care devices because it eliminates the need for connections to multiple pumps and complex tubing connections. A wide range of applications including clinical chemistry, immunoassay, cell analysis, and nucleic acid tests could be demonstrated on a spinning disc. To enable the performance of assays in a fully integrated and automated manner, the robust actuation of integrated valves is a prerequisite. However, conventional passive-type valves incur a critical drawback in that their operation is dependent on the rotational frequency, which is easily influenced by the channel geometry and chemistry, in addition to the physical properties of the liquids to be transferred. Even though a few active-type valving techniques permit the individual actuation of valves, independent of the rotational frequency, complex procedures for the fabrication as well as actuation mechanisms have prevented their broader acceptance in general applications. Here, we report on a lab-on-a-disc incorporating individually addressable diaphragm valves (ID valves) that enable the reversible and thermally stable actuation of multiple valves with unprecedented ease and robustness. These ID valves are configured from an elastic epoxy diaphragm embedded on a 3D printed push-and-twist valve, which can be easily actuated by a simple automatic driver unit. As a proof of concept experiment, an enzyme-linked immunosorbent assay (ELISA) and a polymerase chain reaction (PCR) were performed on a disc in a fully automated manner to demonstrate the robust, reversible, leak-free, and thermally stable actuation of the valves.

  2. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI...

  3. Robotic mitral valve replacement.

    Science.gov (United States)

    Senay, Sahin; Gullu, Ahmet Umit; Kocyigit, Muharrem; Degirmencioglu, Aleks; Karabulut, Hasan; Alhan, Cem

    2014-01-01

    Robotic surgical techniques allow surgeons to perform mitral valve surgery. This procedure has gained acceptance, particularly for mitral valve repair in degenerative mitral disease. However, mitral repair may not always be possible, especially in severely calcified mitral valve of rheumatic origin. This study demonstrates the basic concepts and technique of robotic mitral valve replacement for valve pathologies that are not suitable for repair.

  4. Automatic shutoff valve

    Science.gov (United States)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  5. Adjustable safety relief valve

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, W.L.

    1990-06-12

    This patent describes a pressure relief valve having a relief set pressure. It comprises: a valve body having a fluid inlet and outlet, a spherical, metal valve seat associated with the inlet and a valve member comprising at least a portion of a spherical,metal ball attached to a ball holding element, the valve member being biased against the valve seat and thus providing a metal-to-metal seal preventing the passage of fluids past the valve seat when the fluid pressure in the inlet is below the relief pressure setting of the valve.

  6. Local serotonin mediates cyclic strain-induced phenotype transformation, matrix degradation, and glycosaminoglycan synthesis in cultured sheep mitral valves.

    Science.gov (United States)

    Lacerda, Carla M R; Kisiday, John; Johnson, Brennan; Orton, E Christopher

    2012-05-15

    This study addressed the following questions: 1) Does cyclic tensile strain induce protein expression patterns consistent with myxomatous degeneration in mitral valves? 2) Does cyclic strain induce local serotonin synthesis in mitral valves? 3) Are cyclic strain-induced myxomatous protein expression patterns in mitral valves dependent on local serotonin? Cultured sheep mitral valve leaflets were subjected to 0, 10, 20, and 30% cyclic strain for 24 and 72 h. Protein levels of activated myofibroblast phenotype markers, α-smooth muscle actin (α-SMA) and nonmuscle embryonic myosin (SMemb); matrix catabolic enzymes, matrix metalloprotease (MMP) 1 and 13, and cathepsin K; and sulfated glycosaminoglycan (GAG) content in mitral valves increased with increased cyclic strain. Serotonin was present in the serum-free media of cultured mitral valves and concentrations increased with cyclic strain. Expression of the serotonin synthetic enzyme tryptophan hydroxylase 1 (TPH1) increased in strained mitral valves. Pharmacologic inhibition of the serotonin 2B/2C receptor or TPH1 diminished expression of phenotype markers (α-SMA and SMemb) and matrix catabolic enzyme (MMP1, MMP13, and cathepsin K) expression in 10- and 30%-strained mitral valves. These results provide first evidence that mitral valves synthesize serotonin locally. The results further demonstrate that tensile loading modulates local serotonin synthesis, expression of effector proteins associated with mitral valve degeneration, and GAG synthesis. Inhibition of serotonin diminishes strain-mediated protein expression patterns. These findings implicate serotonin and tensile loading in mitral degeneration, functionally link the pathogeneses of serotoninergic (carcinoid, drug-induced) and degenerative mitral valve disease, and have therapeutic implications.

  7. Research and Technology Development Activities to Address the DOE-EM Environmental Mercury Challenge

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M [ORNL; Peterson, Mark J [ORNL

    2017-01-01

    Human activities have altered trace metal distributions globally. This is especially true for the trace metal mercury (Hg), a pervasive global pollutant that can be methylated to form highly toxic methylmercury (MeHg), which bioaccumulates in aquatic food webs, endangering humans and other biota. Currently there are more than 3,000 mercury-contaminated sites identified worldwide and the United Nations Environment Programme has recently highlighted the risk of this contamination to human health [1, 2]. The Oak Ridge Reservation (ORR) represents an example of one of these mercury-contaminated sites. Unlike other contaminants metals, radionuclides, and organic solvents that impact the Department of Energy Office of Environmental Management (DOE-EM) cleanup program at the ORR and other DOE sites, mercury has several unique characteristics that make environmental remediation of the Y-12 National Security Complex one of the most formidable challenges ever encountered. These distinctive physicochemical properties for mercury include the following: it is a liquid at ambient temperature and pressure; it is the only metal that biomagnifies; and it is the only contaminant transported as a cation, as a dissolved or gaseous elemental metal (similar to an organic solvent), or as both a cation and a dissolved or gaseous elemental metal under environmental conditions. Because of these complexities, implementing cost effective and sustainable solutions that reduce mercury flux from various primary and secondary contamination sources will require linking basic science understanding and applied research advancements into Oak Ridge Office of Environmental Management s (OREM) cleanup process. Currently, DOE is investing in mercury-related research through a variety of programs, including the Office of Science sponsored Critical Interfaces Science Focus Area, EM headquarters sponsored Applied Field Research Initiative, OREM-sponsored Lower East Fork Poplar Creek (LEFPC) Mercury

  8. Counselling low-back-pain patients in secondary healthcare: a randomised trial addressing experienced workplace barriers and physical activity

    DEFF Research Database (Denmark)

    Jensen, Lone Donbæk; Maribo, Thomas; Schiøttz-Christensen, Berit;

    2012-01-01

    OBJECTIVE: To assess if counselling by an occupational physician (OP) addressing experienced workplace barriers and physical activity integrated as a part of low-back pain (LBP) outpatient treatment influences pain, function and sick leave. METHODS: Randomised controlled trial in the secondary...... addressing both workplace barriers and leisure-time physical activity. A workplace visit was performed if required. Pain, function and duration of sick leave due to LBP were primary outcomes. RESULTS: A reduction in bodily pain and improvement in physical function both measured by the 36-item short...... physical activity and maximum oxygen uptake, supported compliance and adherence to the part of the intervention focusing on enhanced physical activity. CONCLUSION: Two short counselling sessions by an OP combining advice on meeting workplace barriers and enhancing physical activity had a substantial effect...

  9. Valve-in-valve-in-valve: Treating endocarditis of a transcatheter heart valve.

    Science.gov (United States)

    Nguyen, Caroline; Cheong, Adrian P; Himbert, Dominique

    2015-10-01

    Transcatheter heart valve endocarditis is a rare, but life threatening complication. We describe the case of a patient who was successfully treated by transcatheter aortic valve-in-valve-in-valve replacement with a favorable 1-year outcome, despite severe early complications.

  10. Microfluidic sieve valves

    Science.gov (United States)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  11. Mechanical Designs for Relief Valves for Cryogenic Apparatuses and Installations

    CERN Document Server

    CERN. Geneva

    2016-01-01

    There are also pressure relief valves with warm seat available on which the set pressure is based on an adjustment of forces by permanent magnets. Pressure vessel rules allows also the choice for an active triggered pressure relief valve (Cont...

  12. Scissor thrust valve actuator

    Science.gov (United States)

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  13. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    Science.gov (United States)

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.

    2016-01-01

    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  14. [Interventional mitral valve replacement. Current status].

    Science.gov (United States)

    Lutter, G; Frank, D

    2016-02-01

    Approximately 30 % of patients suffering from severe valvular heart disease, such as mitral valve regurgitation are non-compliant to the gold standard of minimally invasive surgery, reconstruction or valve replacement. The number of these mostly old patients with severe comorbidities is increasing; therefore, transcatheter interventions have been developed to address an unmet clinical need and may be an alternative therapeutic option to the reference standard. Apart from the successful MitraClip therapy, alternative transcatheter reconstruction technologies are being developed. As with transcatheter aortic valve implantation (TAVI) procedures, the off-pump implantation of a valved stent into the mitral position mainly via a transapical approach will be of great benefit. Recently, the feasibility of transcatheter mitral valved stent implantation in high-risk patients has already been reported.

  15. Safety Design Requirements for Active Hazard Mitigation Device (AHMD) Employed to Address Fast and Slow Cook-off Thermal Threats

    Science.gov (United States)

    2014-12-18

    DOD Fuze Engineering Standardization Working Group U.S. Army Armament Research, Development, and Engineering Center ATTN: RDAR-EIZ / Building 6...ACTIVITY: DOD Fuze Engineering Standardization Working Group U.S. Army Armament Research, Development, and Engineering Center ATTN: RDAR-EIZ...addressed to: Chairman, DOD Fuze Engineering Standardization Working Group, U.S. Army Armament Research, Development, and Engineering Center (RDAR

  16. Which valve is which?

    Directory of Open Access Journals (Sweden)

    Pravin Saxena

    2015-01-01

    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  17. Have guidelines addressing physical activity been established in nonalcoholic fatty liver disease?

    Institute of Scientific and Technical Information of China (English)

    Carmine Finelli; Giovanni Tarantino

    2012-01-01

    The purpose of this review was to highlight,in relation to the currently accepted pathophysiology of non-alcoholic fatty liver disease (NAFLD),the known exercise habits of patients with NAFLD and to detail the benefits of lifestyle modification with exercise (and/or physical activity) on parameters of metabolic syndrome.More rigorous,controlled studies of longer duration and defined histopathological end-points comparing exercise alone and other treatment are needed before better,evidence-based physical activity modification guidelines can be established,since several questions remain unanswered.

  18. Counselling low-back-pain patients in secondary healthcare: a randomised trial addressing experienced workplace barriers and physical activity

    DEFF Research Database (Denmark)

    Jensen, Lone Donbæk; Maribo, Thomas; Schiøttz-Christensen, Berit

    2012-01-01

    OBJECTIVE: To assess if counselling by an occupational physician (OP) addressing experienced workplace barriers and physical activity integrated as a part of low-back pain (LBP) outpatient treatment influences pain, function and sick leave. METHODS: Randomised controlled trial in the secondary...... addressing both workplace barriers and leisure-time physical activity. A workplace visit was performed if required. Pain, function and duration of sick leave due to LBP were primary outcomes. RESULTS: A reduction in bodily pain and improvement in physical function both measured by the 36-item short......-form health survey questionnaire in favour of the intervention group was found. The change in pain score was found to be clinically relevant. The risk of sick leave for at least 8 weeks due to LBP was significantly reduced in the intervention group. Two secondary outcomes, Fear Avoidance Beliefs about...

  19. Coronary embolism in a patient with mitral valve prosthesis: successful management with tirofiban and half-dose tissue-type plasminogen activator

    Institute of Scientific and Technical Information of China (English)

    Yusuf Atmaca; Cagdas Ozdol; Cetin Erol

    2007-01-01

    @@ Coronary embolism has been considered as a rare cause of coronary occlusion.Prosthetic heart valve is an infrequent cause of this condition.The exact incidence of coronary embolization in patients with prosthetic heart valves is not well known.

  20. Aortic Valve Regurgitation

    Science.gov (United States)

    ... inside your heart that involves heart valves. Rheumatic fever. Rheumatic fever — a complication of strep throat and once a ... the United States — can damage the aortic valve. Rheumatic fever is still prevalent in developing countries but rare ...

  1. Pulmonary Valve Stenosis

    Science.gov (United States)

    ... growths called carcinoid tumors in the digestive system. Rheumatic fever. This complication of an infection caused by streptococcus ... valve stenosis later in life, including: Carcinoid syndrome Rheumatic fever Noonan's syndrome Mild to moderate pulmonary valve stenosis ...

  2. Aortic Valve Disease

    Science.gov (United States)

    ... Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that are ... Transplantation End-stage Lung Disease Adult Lung Transplantation Pediatric Lung ... Aortic Aneurysm Aortic Valve Disease Overview The human heart has ...

  3. Mitral Valve Stenosis

    Science.gov (United States)

    ... up around the ring around the mitral valve (annulus), which can occasionally cause mitral valve stenosis. Other ... the condition of your lungs. Transesophageal echocardiogram. A small transducer attached to the end of a tube ...

  4. Heart valve surgery

    Science.gov (United States)

    ... Tricuspid valve stenosis Risks The risks of having cardiac surgery include: Death Heart attack Heart failure Bleeding requiring ... and the A.D.A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Latest ...

  5. Addressing fundamental architectural challenges of an activity-based intelligence and advanced analytics (ABIAA) system

    Science.gov (United States)

    Yager, Kevin; Albert, Thomas; Brower, Bernard V.; Pellechia, Matthew F.

    2015-06-01

    The domain of Geospatial Intelligence Analysis is rapidly shifting toward a new paradigm of Activity Based Intelligence (ABI) and information-based Tipping and Cueing. General requirements for an advanced ABIAA system present significant challenges in architectural design, computing resources, data volumes, workflow efficiency, data mining and analysis algorithms, and database structures. These sophisticated ABI software systems must include advanced algorithms that automatically flag activities of interest in less time and within larger data volumes than can be processed by human analysts. In doing this, they must also maintain the geospatial accuracy necessary for cross-correlation of multi-intelligence data sources. Historically, serial architectural workflows have been employed in ABIAA system design for tasking, collection, processing, exploitation, and dissemination. These simpler architectures may produce implementations that solve short term requirements; however, they have serious limitations that preclude them from being used effectively in an automated ABIAA system with multiple data sources. This paper discusses modern ABIAA architectural considerations providing an overview of an advanced ABIAA system and comparisons to legacy systems. It concludes with a recommended strategy and incremental approach to the research, development, and construction of a fully automated ABIAA system.

  6. Counselling low-back-pain patients in secondary healthcare: a randomised trial addressing experienced workplace barriers and physical activity.

    Science.gov (United States)

    Jensen, Lone Donbæk; Maribo, Thomas; Schiøttz-Christensen, Berit; Madsen, Finn Hjorth; Gonge, Bigitte; Christensen, Michael; Frost, Poul

    2012-01-01

    To assess if counselling by an occupational physician (OP) addressing experienced workplace barriers and physical activity integrated as a part of low-back pain (LBP) outpatient treatment influences pain, function and sick leave. Randomised controlled trial in the secondary healthcare sector with 3 months' follow-up. The participants were LBP patients who, independently of sick-leave status, expressed concerns about the ability to maintain their current job. Patients referred for surgery were excluded. The intervention consisted of two counselling sessions conducted by an OP addressing both workplace barriers and leisure-time physical activity. A workplace visit was performed if required. Pain, function and duration of sick leave due to LBP were primary outcomes. A reduction in bodily pain and improvement in physical function both measured by the 36-item short-form health survey questionnaire in favour of the intervention group was found. The change in pain score was found to be clinically relevant. The risk of sick leave for at least 8 weeks due to LBP was significantly reduced in the intervention group. Two secondary outcomes, Fear Avoidance Beliefs about physical activity and maximum oxygen uptake, supported compliance and adherence to the part of the intervention focusing on enhanced physical activity. Two short counselling sessions by an OP combining advice on meeting workplace barriers and enhancing physical activity had a substantial effect on important prognostic factors for LBP patients with moderate to severe symptoms diagnosed in outpatient rheumatological clinics. Current Controlled Trials ISRCTN13071157.

  7. Set of Activities Addressed for Elementary School Students: Cells and the Genetic Material

    Directory of Open Access Journals (Sweden)

    E.M. Miranda

    2005-07-01

    Full Text Available The time lag between the progresses in the area of molecular biology reached in the last years and the schools science curricula  can be reduced through  initiatives of the university  regarding  the dissemina- tion of sciences. Inside of this context, one of the major objectives of the CBME has been the scientific education  and  dissemination on Molecular  Biosciences.  Among the  strategies organized  to promote the dissemination of this area, the Scientific Dissemination Coordination of CBME developed a set of playful activities  for students from public and private  elementary schools (7th  and 8th grades.  As a first step science teachers were interviewed  in order to indicate  which topics related  to molecular bio- sciences they  usually  include in their curricula  planning.  The approach  considered  in the elaboration of the set of activities  was the construction of knowledge of the concepts related  to topics as cell types, their  structures and  organelles,  and  the  importance of the  nucleus and  DNA. The set was offered to170 students. Students from private  schools were evaluated by their  performance  through  the classes, which were registered  by the  notes  of the  instructors.  Students from public  schools were evaluated through  questionnaires containing  basic  concepts  on the  theme  applied  before (pre-test and  after (post-test the set of activities  in order to measure,  respectively,  the previous and acquired knowledge. The  programming accomplished  at  the  public  school was partially modified  due  to  the  absence  of a laboratory, microscopes  and  a room  of computers, without, however,  to  alter  the  objectives  and content of the  activities.   The  comparative analysis  of the  pre- and  post-tests revealed  that, in this latter, there  was an increase of the average percentage  of correct  answers and an

  8. “Fair Play”: A Videogame Designed to Address Implicit Race Bias Through Active Perspective Taking

    Science.gov (United States)

    Kaatz, Anna; Chu, Sarah; Ramirez, Dennis; Samson-Samuel, Clem; Carnes, Molly

    2014-01-01

    Abstract Objective: Having diverse faculty in academic health centers will help diversify the healthcare workforce and reduce health disparities. Implicit race bias is one factor that contributes to the underrepresentation of Black faculty. We designed the videogame “Fair Play” in which players assume the role of a Black graduate student named Jamal Davis. As Jamal, players experience subtle race bias while completing “quests” to obtain a science degree. We hypothesized that participants randomly assigned to play the game would have greater empathy for Jamal and lower implicit race bias than participants randomized to read narrative text describing Jamal's experience. Materials and Methods: University of Wisconsin–Madison graduate students were recruited via e-mail and randomly assigned to play “Fair Play” or read narrative text through an online link. Upon completion, participants took an Implicit Association Test to measure implicit bias and answered survey questions assessing empathy toward Jamal and awareness of bias. Results: As hypothesized, gameplayers showed the least implicit bias but only when they also showed high empathy for Jamal (P=0.013). Gameplayers did not show greater empathy than text readers, and women in the text condition reported the greatest empathy for Jamal (P=0.008). However, high empathy only predicted lower levels of implicit bias among those who actively took Jamal's perspective through gameplay (P=0.014). Conclusions: A videogame in which players experience subtle race bias as a Black graduate student has the potential to reduce implicit bias, possibly because of a game's ability to foster empathy through active perspective taking. PMID:26192644

  9. Isolated Pulmonary Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hatamizadeh

    2009-06-01

    Full Text Available Infective endocarditis is one of the most severe complications of parenteral drug abuse. The outstanding clinical feature of infective endocarditis in intravenous drug abusers is the high incidence of right-sided valve infection, and the tricuspid valve is involved in 60% to 70% of the cases. We herein report a case of isolated pulmonic valve infective endocarditis with a native pulmonary valve.

  10. Aerodynamic Shutoff Valve

    Science.gov (United States)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  11. Presentation of the development of the SRV valve (safety relief valve); Presentation du developpement de la vanne SRV (Safety Relief Valve)

    Energy Technology Data Exchange (ETDEWEB)

    Manguette, P. [Adareg, 59 - Haubourdin (France)

    1998-09-01

    Adareg has 30 years experience in Hydrane and control valves. Its know-how moves towards extreme technologies: control of all types of fluids (hot, cold, aggressive ones, clean ones etc... ). A perfect control is essential for very low temperatures (nuclear submarines, Ariane). Adareg Research and Development activities, certified ISO 9001, have developed valves accepting temperatures reaching 2 degrees above the absolute 0. Increasing requirements concerning low temperatures have encouraged Adareg to develop a research programme in partnership with CEA - French Atomic Energy Commission - for valves type 'SRV' (Safety Relief Valves). This type of valve is designed for a new accelerator of particles, the LHC, at CERN, in Geneva. (author)

  12. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  13. Dump valve assembly

    Science.gov (United States)

    Owen, T.J.

    1984-01-01

    A dump valve assembly comprising a body having a bore defined by a tapered wall and a truncated spherical valve member adapted to seat along a spherical surface portion thereof against said tapered wall. Means are provided for pivoting said valve member between a closed position engagable with said tapered wall and an open position disengaged therefrom.

  14. Quadricuspid Aortic Valve

    Directory of Open Access Journals (Sweden)

    Mehmet Taşar

    2013-03-01

    Full Text Available Quadricuspid aortic valve is an extremely rare congenital defect. Isolated form appears frequently. It is seen with aortic valve regurgitation in adulthood. This case report presents a rare clinical finding of an isolated quadricuspid aortic valve with aortic regurgitation in an 64-year-old female who was referred for cardiac evaluation due to newly identified murmur.

  15. Inaugural address

    Science.gov (United States)

    Joshi, P. S.

    2014-03-01

    From jets to cosmos to cosmic censorship P S Joshi Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India E-mail: psj@tifr.res.in 1. Introduction At the outset, I should like to acknowledge that part of the title above, which tries to capture the main flavour of this meeting, and has been borrowed from one of the plenary talks at the conference. When we set out to make the programme for the conference, we thought of beginning with observations on the Universe, but then we certainly wanted to go further and address deeper questions, which were at the very foundations of our inquiry, and understanding on the nature and structure of the Universe. I believe, we succeeded to a good extent, and it is all here for you in the form of these Conference Proceedings, which have been aptly titled as 'Vishwa Mimansa', which could be possibly translated as 'Analysis of the Universe'! It is my great pleasure and privilege to welcome you all to the ICGC-2011 meeting at Goa. The International Conference on Gravitation and Cosmology (ICGC) series of meetings are being organized by the Indian Association for General Relativity and Gravitation (IAGRG), and the first such meeting was planned and conducted in Goa in 1987, with subsequent meetings taking place at a duration of about four years at various locations in India. So, it was thought appropriate to return to Goa to celebrate the 25 years of the ICGC meetings. The recollections from that first meeting have been recorded elsewhere here in these Proceedings. The research and teaching on gravitation and cosmology was initiated quite early in India, by V V Narlikar at the Banares Hindu University, and by N R Sen in Kolkata in the 1930s. In course of time, this activity grew and gained momentum, and in early 1969, at the felicitation held for the 60 years of V V Narlikar at a conference in Ahmedabad, P C Vaidya proposed the formation of the IAGRG society, with V V Narlikar being the first President. This

  16. Proposed Activities to Address Regulatory Gaps and Challenges for Licensing Advanced Reactors Using Seismic Isolation

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kammerer, Annie M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Whittaker, Andrew S. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-12-01

    Over the last decade, particularly since implementation of the certified design regulatory approaches outlined in 10 CFR 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” interest has been increasing in the use of seismic isolation (SI) technology to support seismic safety in nuclear facilities. In 2009, the United States (U.S.) Nuclear Regulatory Commission (NRC) initiated research activities to develop new guidance targeted at isolated facilities because SI is being considered for nuclear power plants in the U.S. One product of that research, which was developed around a risk-informed regulatory approach, is a draft NRC NUREG series (NUREG/CR) report that investigates and discusses considerations for use of SI in otherwise traditionally founded large light water reactors (LWRs). A coordinated effort led to new provisions for SI of LWRs in the American Society of Civil Engineers standard ASCE/SEI 4-16, “Seismic Analysis of Safety Related Nuclear Structures.” The risk-informed design philosophy that underpinned development of the technical basis for these documents led to a set of proposed performance objectives and acceptance criteria intended to serve as the foundation for future NRC guidance on the use of SI and related technology. Although the guidance provided in the draft SI NUREG/CR report and ASCE/SEI 4 16 provides a sound basis for further development of nuclear power plant designs incorporating SI, these initial documents were focused on surface-founded or near-surface-founded LWRs and were, necessarily, limited in scope. For example, there is limited information in both the draft NUREG/CR report and ASCE/SEI 4-16 related to nonlinear analysis of soil-structure systems for deeply-embedded reactors, the isolation of components, and the use of vertical isolation systems. Also not included in the draft SI NUREG/CR report are special considerations for licensing of isolated facilities using the certified design approach in 10 CFR

  17. The bacterial elicitor flagellin activates its receptor in tomato cells according to the address-message concept.

    Science.gov (United States)

    Meindl, T; Boller, T; Felix, G

    2000-09-01

    flg22, a peptide corresponding to the most conserved domain of bacterial flagellin, acts as a potent elicitor in plants. Here, we have used an iodinated derivative of flg22 ((125)I-labeled Tyr-flg22) as a molecular probe for the flagellin receptor in tomato cells. This radioligand showed rapid binding to a single class of specific, saturable, high-affinity receptor sites in intact cells and membrane preparations. Binding, although essentially nonreversible under physiological conditions, was not covalent, and chemical cross-linking was required to specifically label a single polypeptide of 115 kD. Intact flagellin and elicitor-active flagellin peptides but not biologically inactive analogs efficiently competed for binding of radioligand. Peptides lacking the C terminus of the conserved domain, previously found to act as competitive antagonists of elicitor action in tomato cells, also competed for binding of radioligand. Thus, this novel, high-affinity binding site exhibited all the characteristics expected of a functional receptor of bacterial flagellin. For a model of receptor activation, we propose a two-step mechanism according to the address-message concept, in which binding of the N terminus (address) is the first step and activation of responses with the C terminus (message) is the second step.

  18. Activating people to address their health care needs: learning from people with lived experience of chronic illnesses.

    Science.gov (United States)

    Stanhope, Victoria; Henwood, Benjamin F

    2014-08-01

    One of the primary goals of health care reform is improving the quality and reducing the costs of care for people with co-morbid mental health and physical health conditions. One strategy is to integrate primary and behavioral health care through care coordination and patient activation. This qualitative study using community based participatory research methods informs the development of integrated care by presenting the perspectives of those with lived experience of chronic illnesses and homelessness. Themes presented include the internal and external barriers to addressing health needs and the key role of peer support in overcoming these barriers.

  19. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  20. Transcatheter Aortic Valve Replacement: A Review Article

    Directory of Open Access Journals (Sweden)

    Juan A Siordia

    2016-06-01

    Full Text Available Transcatheter aortic valve replacement (TAVR is a novel therapeutic intervention for the replacement of severely stenotic aortic valves in high-risk patients for standard surgical procedures. Since the initial PARTNER trial results, use of TAVR has been on the rise each year. New delivery methods and different valves have been developed and modified in order to promote the minimally invasive procedure and reduce common complications, such as stroke. This review article focuses on the current data on the indications, risks, benefits, and future directions of TAVR. Recently, TAVR has been considered as a standard-of-care procedure. While this technique is used frequently in high-risk surgical candidates, studies have been focusing on the application of this method for younger patients with lower surgical risk. Moreover, several studies have proposed promising results regarding the use of valve-in-valve technique or the procedure in which the valve is placed within a previously implemented bioprosthetic valve. However, ischemic strokes and paravalvular leak remain a matter of debate in these surgeries. New methods and devices have been developed to reduce the incidence of post-procedural stroke. While the third generation of TAVR valves (i.e., Edwards Sapien 3 and Medtronic Evolut R addresses the issue of paravalvular leak structurally, results on their efficacy in reducing the risk of paravalvular leak are yet to be obtained. Furthermore, TAVR enters the field of hybrid methods in the treatment of cardiac issues via both surgical and catheter-based approaches. Finally, while TAVR is primarily performed on cases with aortic stenosis, new valves and methods have been proposed regarding the application of this technique in aortic regurgitation, as well as other aortic pathologies. TAVR is a suitable therapeutic approach for the treatment of aortic stenosis in high-risk patients. Considering the promising results in the current patient population

  1. Activity theory as a tool to address the problem of chemistry's lack of relevance in secondary school chemical education

    Science.gov (United States)

    van Aalsvoort, Joke

    In a previous article, the problem of chemistry's lack of relevance in secondary chemical education was analysed using logical positivism as a tool. This article starts with the hypothesis that the problem can be addressed by means of activity theory, one of the important theories within the sociocultural school. The reason for this expectation is that, while logical positivism creates a divide between science and society, activity theory offers a model of society in which science and society are related. With the use of this model, a new course for grade nine has been constructed. This results in a confirmation of the hypothesis, at least at a theoretical level. A comparison with the Salters' approach is made in order to demonstrate the relative merits of a mediated way of dealing with the problem of the lack of relevance of chemistry in chemical education.

  2. Welcome Address

    Science.gov (United States)

    Kiku, H.

    2014-12-01

    Ladies and Gentlemen, It is an honor for me to present my welcome address in the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3), as the president of Kanto Gakuin University. Particularly to those from abroad more than 17 countries, I am very grateful for your participation after long long trips from your home to Yokohama. On the behalf of the Kanto Gakuin University, we certainly welcome your visit to our university and stay in Yokohama. First I would like to introduce Kanto Gakuin University briefly. Kanto Gakuin University, which is called KGU, traces its roots back to the Yokohama Baptist Seminary founded in 1884 in Yamate, Yokohama. The seminary's founder was Albert Arnold Bennett, alumnus of Brown University, who came to Japan from the United States to establish a theological seminary for cultivating and training Japanese missionaries. Now KGU is a major member of the Kanto Gakuin School Corporation, which is composed of two kindergartens, two primary schools, two junior high schools, two senior high schools as well as KGU. In this university, we have eight faculties with graduate school including Humanities, Economics, Law, Sciences and Engineering, Architecture and Environmental Design, Human and Environmental Studies, Nursing, and Law School. Over eleven thousands students are currently learning in our university. By the way, my major is the geotechnical engineering, and I belong to the faculty of Sciences and Engineering in my university. Prof. T. Yamada, here, is my colleague in the same faculty. I know that the nuclear physics is one of the most active academic fields in the world. In fact, about half of the participants, namely, more than 50 scientists, come from abroad in this conference. Moreover, I know that the nuclear physics is related to not only the other fundamental physics such as the elementary particle physics and astrophysics but also chemistry, medical sciences, medical cares, and radiation metrology

  3. Valve selection in aortic valve endocarditis

    Science.gov (United States)

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis.

  4. Fault detection and diagnosis of diesel engine valve trains

    Science.gov (United States)

    Flett, Justin; Bone, Gary M.

    2016-05-01

    This paper presents the development of a fault detection and diagnosis (FDD) system for use with a diesel internal combustion engine (ICE) valve train. A novel feature is generated for each of the valve closing and combustion impacts. Deformed valve spring faults and abnormal valve clearance faults were seeded on a diesel engine instrumented with one accelerometer. Five classification methods were implemented experimentally and compared. The FDD system using the Naïve-Bayes classification method produced the best overall performance, with a lowest detection accuracy (DA) of 99.95% and a lowest classification accuracy (CA) of 99.95% for the spring faults occurring on individual valves. The lowest DA and CA values for multiple faults occurring simultaneously were 99.95% and 92.45%, respectively. The DA and CA results demonstrate the accuracy of our FDD system for diesel ICE valve train fault scenarios not previously addressed in the literature.

  5. Welcome Address

    OpenAIRE

    Shantanu Sengupta

    1983-01-01

    This article is part of the NEDA-PIDS Seminar-Workshop on the Philippine System of National Accounts. It outlines the seminar’s major objectives and the problems and issues that need to be addressed. It argues that coordination among institutions can lead to effective resolution to sensitive issues.

  6. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    Science.gov (United States)

    2016-03-09

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  7. JenaValve.

    Science.gov (United States)

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm

    2012-09-01

    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future.

  8. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  9. Role of concomitant tricuspid surgery in moderate functional tricuspid regurgitation in patients undergoing left heart valve surgery.

    Science.gov (United States)

    Mahesh, Balakrishnan; Wells, Francis; Nashef, Samer; Nair, Sukumaran

    2013-01-01

    Functional tricuspid regurgitation (FTR) is frequently present in patients undergoing aortic, and particularly mitral valve, surgery. Untreated FTR may lead to right heart failure. Reoperative cardiac surgery for late FTR is associated with high morbidity and mortality. Therefore, severe FTR has emerged as a Class I indication for concomitant tricuspid valve surgery in patients undergoing left valve surgery. Concomitant tricuspid valve surgery during left heart valve surgery to address moderate and mild FTR is controversial. This review addresses this issue and proposes an algorithm for the treatment of FTR in patients undergoing left heart valve surgery.

  10. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves

    DEFF Research Database (Denmark)

    Johansen, Peter; Engholt, Henrik; Tang, Mariann

    2017-01-01

    AIMS: Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, at smaller sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be frac...

  11. The Small Helm Project: an academic activity addressing international corruption for undergraduate civil engineering and construction management students.

    Science.gov (United States)

    Benzley, Steven E

    2006-04-01

    This paper presents an academic project that addresses the issue of international corruption in the engineering and construction industry, in a manner that effectively incorporates several learning experiences. The major objectives of the project are to provide the students a learning activity that will 1) make a meaningful contribution within the disciplines being studied; 2) teach by experience a significant principle that can be valuable in numerous situations during an individual's career, and 3) engage the minds, experiences, and enthusiasm of the participants in a real ethical challenge that is prevalent in all of their chosen professional fields. The paper describes the full details of the project, the actual implementation of it during Winter Semester 2005, the experiences gained during the initial trial, and the modifications and improvements incorporated for future implementation.

  12. Modeling the Mitral Valve

    Science.gov (United States)

    Kaiser, Alexander

    2016-11-01

    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  13. Mitral valve prolapse.

    Science.gov (United States)

    Gould, L; Gopalaswamy, C

    1984-05-01

    Mitral valve prolapse is a very common condition. It occurs in 4-5% of the population. It may be idiopathic or associated with a number of other conditions. Myxomatous degeneration is the underlying mechanism of mitral valve prolapse. Most patients with mitral valve prolapse have no symptoms. When symptoms do occur, palpitations, chest pain and dyspnea are the major complaints. The midsystolic click occasionally followed by the late systolic murmur are the typical physical findings. The echocardiogram plays a big role in the diagnosis of mitral valve prolapse. The beta blockers are used in the treatment of the symptomatic patient.

  14. Biological heart valves.

    Science.gov (United States)

    Ciubotaru, Anatol; Cebotari, Serghei; Tudorache, Igor; Beckmann, Erik; Hilfiker, Andres; Haverich, Axel

    2013-10-01

    Cardiac valvular pathologies are often caused by rheumatic fever in young adults, atherosclerosis in elderly patients, or by congenital malformation of the heart in children, in effect affecting almost all population ages. Almost 300,000 heart valve operations are performed worldwide annually. Tissue valve prostheses have certain advantages over mechanical valves such as biocompatibility, more physiological hemodynamics, and no need for life-long systemic anticoagulation. However, the major disadvantage of biological valves is related to their durability. Nevertheless, during the last decade, the number of patients undergoing biological, rather than mechanical, valve replacement has increased from half to more than three-quarters for biological implants. Continuous improvement in valve fabrication includes development of new models and shapes, novel methods of tissue treatment, and preservation and implantation techniques. These efforts are focused not only on the improvement of morbidity and mortality of the patients but also on the improvement of their quality of life. Heart valve tissue engineering aims to provide durable, "autologous" valve prostheses. These valves demonstrate adaptive growth, which may avoid the need of repeated operations in growing patients.

  15. Valve replacement in children: a challenge for a whole life.

    Science.gov (United States)

    Henaine, Roland; Roubertie, François; Vergnat, Mathieu; Ninet, Jean

    2012-10-01

    Valvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population.

  16. A piezoelectrically actuated ball valve

    Science.gov (United States)

    Erwin, L. R.; Schwartz, H. W.; Teitelbaum, B. R.

    1972-01-01

    Bimorph strip composed of two layers of poled piezoelectric ceramic material closes and opens valve. Strip performs like capacitator, allowing initial inrush of current when valve is energized and then only small leakage current flows as valve remains energized.

  17. Dynamic Heterogeneity of the Heart Valve Interstitial Cell Population in Mitral Valve Health and Disease

    Directory of Open Access Journals (Sweden)

    Tori E. Horne

    2015-08-01

    Full Text Available The heart valve interstitial cell (VIC population is dynamic and thought to mediate lay down and maintenance of the tri-laminar extracellular matrix (ECM structure within the developing and mature valve throughout life. Disturbances in the contribution and distribution of valve ECM components are detrimental to biomechanical function and associated with disease. This pathological process is associated with activation of resident VICs that in the absence of disease reside as quiescent cells. While these paradigms have been long standing, characterization of this abundant and ever-changing valve cell population is incomplete. Here we examine the expression pattern of Smooth muscle α-actin, Periostin, Twist1 and Vimentin in cultured VICs, heart valves from healthy embryonic, postnatal and adult mice, as well as mature valves from human patients and established mouse models of disease. We show that the VIC population is highly heterogeneous and phenotypes are dependent on age, species, location, and disease state. Furthermore, we identify phenotypic diversity across common models of mitral valve disease. These studies significantly contribute to characterizing the VIC population in health and disease and provide insights into the cellular dynamics that maintain valve structure in healthy adults and mediate pathologic remodeling in disease states.

  18. Human tyrosinase produced in insect cells: a landmark for the screening of new drugs addressing its activity.

    Science.gov (United States)

    Fogal, Stefano; Carotti, Marcello; Giaretta, Laura; Lanciai, Federico; Nogara, Leonardo; Bubacco, Luigi; Bergantino, Elisabetta

    2015-01-01

    Human tyrosinase is the first enzyme of the multistep process of melanogenesis. It catalyzes the hydroxylation of L-tyrosine to L-dihydroxyphenylalanine and the following oxidation of o-diphenol to the corresponding quinone, L-dopaquinone. In spite of its biomedical relevance, its reactivity is far from being fully understood, mostly because of the lack of a suitable expression system. Indeed, until now, studies on substrates and inhibitors of tyrosinases have been performed in vitro almost exclusively using mushroom or bacterial enzymes. We report on the production of a recombinant human tyrosinase in insect cells (Sf9 line). Engineering the protein, improving cell culture conditions, and setting a suitable purification protocol optimized product yield. The obtained active enzyme was truthfully characterized with a number of substrate and inhibitor molecules. These results were compared to those gained from a parallel analysis of the bacterial (Streptomyces antibioticus) enzyme and those acquired from the literature for mushroom tyrosinase, showing that the reactivity of the human enzyme appears unique and pointing out the great bias introduced when using non-human tyrosinases to measure the inhibitory efficacy of new molecules. The described enzyme is therefore an indispensable paradigm in testing pharmaceutical or cosmetic agents addressing tyrosinase activity.

  19. Mitral valve surgery - open

    Science.gov (United States)

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  20. Blocked Urethral Valves

    Science.gov (United States)

    ... Blocked Urethral Valves Health Issues Listen Español Text Size Email Print Share Blocked Urethral Valves Page Content Article Body Urine leaves the bladder through a tube called the urethra, which in boys passes through the penis. Rarely, small membranes form across the urethra in ...

  1. Shutoff and throttling valve

    Science.gov (United States)

    Hays, L. G.

    1974-01-01

    Leaktight shutoff, precise flow control, and very low pressure drop are incorporated in all-metal valve designed for operation under extreme temperatures. Valve constructed with refractory metal is intended for control of high-temperature liquid cesium, but has applications related to control of high- and low-temperature liquids and gases.

  2. Bioprinting a cardiac valve.

    Science.gov (United States)

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering.

  3. Anticoagulation for Prosthetic Valves

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Kaneko

    2013-01-01

    Full Text Available Implantation of prosthetic valve requires consideration for anticoagulation. The current guideline recommends warfarin on all mechanical valves. Dabigatran is the new generation anticoagulation medication which is taken orally and does not require frequent monitoring. This drug is approved for treatment for atrial fibrillation and venous thromboembolism, but the latest large trial showed that this drug increases adverse events when used for mechanical valve anticoagulation. On-X valve is the new generation mechanical valve which is considered to require less anticoagulation due to its flow dynamics. The latest study showed that lower anticoagulation level lowers the incidence of bleeding, while the risk of thromboembolism and thrombosis remained the same. Anticoagulation poses dilemma in cases such as pregnancy and major bleeding event. During pregnancy, warfarin can be continued throughout pregnancy and switched to heparin derivative during 6–12 weeks and >36 weeks of gestation. Warfarin can be safely started after 1-2 weeks of discontinuation following major bleeding episode.

  4. Welcome Address

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@  On behalf of the International Life Sciences Institute, I welcome you to Beijing and to the Third Asian Conference on Food Safety and Nutrition. Many of you will remember the first Asian conference on Food Safety held in Kuala Lumpur in 1990 and the second held in Bangkok in 1994. These meetings have been so successful that ILSI made the commitment to host such a conference periodically in order to provide a forum to share the latest information and to set new goals and priorities.   This year, we have broadened the scope of the agenda to include issues on nutrition. I want to thank all of our co-sponsors and members of the Planning Committee for preparing such a comprehensive and timely program. Some of the issues and challenges facing Asia that will be addressed at this meeting are:

  5. Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems

    Science.gov (United States)

    Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John

    2010-01-01

    Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.

  6. Loss of Axin2 results in impaired heart valve maturation and subsequent myxomatous valve disease.

    Science.gov (United States)

    Hulin, Alexia; Moore, Vicky; James, Jeanne M; Yutzey, Katherine E

    2017-01-01

    Myxomatous valve disease (MVD) is the most common aetiology of primary mitral regurgitation. Recent studies suggest that defects in heart valve development can lead to heart valve disease in adults. Wnt/β-catenin signalling is active during heart valve development and has been reported in human MVD. The consequences of increased Wnt/β-catenin signalling due to Axin2 deficiency in postnatal valve remodelling and pathogenesis of MVD were determined. To investigate the role of Wnt/β-catenin signalling, we analysed heart valves from mice deficient in Axin2 (KO), a negative regulator of Wnt/β-catenin signalling. Axin2 KO mice display enlarged mitral and aortic valves (AoV) after birth with increased Wnt/β-catenin signalling and cell proliferation, whereas Sox9 expression and collagen deposition are decreased. At 2 months in Axin2 KO mice, the valve extracellular matrix (ECM) is stratified but distal AoV leaflets remain thickened and develop aortic insufficiency. Progressive myxomatous degeneration is apparent at 4 months with extensive ECM remodelling and focal aggrecan-rich areas, along with increased BMP signalling. Infiltration of inflammatory cells is also observed in Axin2 KO AoV prior to ECM remodelling. Overall, these features are consistent with the progression of human MVD. Finally, Axin2 expression is decreased and Wnt/β-catenin signalling is increased in myxomatous mitral valves in a murine model of Marfan syndrome, supporting the importance of Wnt/β-catenin signalling in the development of MVD. Altogether, these data indicate that Axin2 limits Wnt/β-catenin signalling after birth and allows proper heart valve maturation. Moreover, dysregulation of Wnt/β-catenin signalling resulting from loss of Axin2 leads to progressive MVD. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.

  7. Inhibitory role of Notch1 in calcific aortic valve disease.

    Directory of Open Access Journals (Sweden)

    Asha Acharya

    Full Text Available Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs. We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.

  8. Face-Sealing Butterfly Valve

    Science.gov (United States)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  9. Presidential address.

    Science.gov (United States)

    Vohra, U

    1993-07-01

    The Secretary of India's Ministry of Health and Family Welfare serves as Chair of the Executive Council of the International Institute for Population Sciences in Bombay. She addressed its 35th convocation in 1993. Global population stands at 5.43 billion and increases by about 90 million people each year. 84 million of these new people are born in developing countries. India contributes 17 million new people annually. The annual population growth rate in India is about 2%. Its population size will probably surpass 1 billion by the 2000. High population growth rates are a leading obstacle to socioeconomic development in developing countries. Governments of many developing countries recognize this problem and have expanded their family planning programs to stabilize population growth. Asian countries that have done so and have completed the fertility transition include China, Japan, Singapore, South Korea, and Thailand. Burma, Malaysia, North Korea, Sri Lanka, and Vietnam have not yet completed the transition. Afghanistan, Bangladesh, Iran, Nepal, and Pakistan are half-way through the transition. High population growth rates put pressure on land by fragmenting finite land resources, increasing the number of landless laborers and unemployment, and by causing considerable rural-urban migration. All these factors bring about social stress and burden civic services. India has reduced its total fertility rate from 5.2 to 3.9 between 1971 and 1991. Some Indian states have already achieved replacement fertility. Considerable disparity in socioeconomic development exists among states and districts. For example, the states of Bihar, Madhya Pradesh, Rajasthan, and Uttar Pradesh have female literacy rates lower than 27%, while that for Kerala is 87%. Overall, infant mortality has fallen from 110 to 80 between 1981 and 1990. In Uttar Pradesh, it has fallen from 150 to 98, while it is at 17 in Kerala. India needs innovative approaches to increase contraceptive prevalence rates

  10. Mesofluidic two stage digital valve

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, John F; Love, Lonnie J; Lind, Randall F; Richardson, Bradley S

    2013-12-31

    A mesofluidic scale digital valve system includes a first mesofluidic scale valve having a valve body including a bore, wherein the valve body is configured to cooperate with a solenoid disposed substantially adjacent to the valve body to translate a poppet carried within the bore. The mesofluidic scale digital valve system also includes a second mesofluidic scale valve disposed substantially perpendicular to the first mesofluidic scale valve. The mesofluidic scale digital valve system further includes a control element in communication with the solenoid, wherein the control element is configured to maintain the solenoid in an energized state for a fixed period of time to provide a desired flow rate through an orifice of the second mesofluidic valve.

  11. Living artificial heart valve alternatives: a review

    Directory of Open Access Journals (Sweden)

    Flanagan T. C.

    2003-11-01

    Full Text Available Conventional replacement therapies for heart valve disease are associated with significant drawbacks. The field of tissue engineering has emerged as an exciting alternative in the search for improved heart valve replacement structures. One of the principles behind this concept is the transplantation of living elements, embedded in a suitable scaffold material, to the diseased site where the structure becomes integrated with patients' tissue to restore natural function. Significant progress has been made in the last ten years in the development of a living artificial heart valve alternative (LAHVA, with the identification of potential replacement sources for valve cells, scaffolds to maintain the cells in a three-dimensional environment, and signals to promote tissue development. This review addresses the need for a tissue-engineered alternative to current prostheses and provides a detailed account of normal heart valve structure - the blueprint for LAHVA fabrication. The research efforts to create a viable LAHVA, including recent developments, are discussed. Particular attention is focused on the choice of cell source for LAHVA construction, the use of biodegradable natural and synthetic polymeric scaffolds as extracellular matrix derivatives, and exogenous stimulation of tissue growth. The critical challenges involved in LAHVA development and possible future areas of investigation are also discussed.

  12. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    BACKGROUND AND AIMS OF THE STUDY: Prompted by anecdotal evidence and observations by surgeons, an investigation was undertaken into the potential differences in implanted aortic valve prosthesis sizes, during aortic valve replacement (AVR) procedures, between northern and southern European...... countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early...

  13. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  14. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...... similar to the one achieved by the expensive and time-consuming CFD calculations. So CFD is only used in case of entirely new designs or where a very detailed knowledge of the flow is required. Even though rules of thumb are useful for those, who have developed them, Danfoss needs an objective and general...... method that can be used to predict the performance of valves....

  15. A valve disk

    Energy Technology Data Exchange (ETDEWEB)

    Khayrullin, N.A.; Isayev, B.N.; Kruglov, S.A.; Molokanov, Yu.K.; Shchelkunov, V.A.; Shegay, V.R.; Vizhgorodskiy, B.N.

    1982-01-01

    A valve disk is proposed which includes a horizontal bed, on which there are laminar valves arranged in staggered order. To ensure the stable and effective operation of the disk in a broad range of loads by compensating for the direct flow and the partial sectioning of the disk bed, it is equipped with compensating elements installed in openings in the bed and hinged with it. They are made in the form of straight, triangular prisms with ports in the bases. The prisms are installed with the capability of movement relative to the disk bed. The valves are positioned on the upper lateral facets of the compensating elements.

  16. Addressing key concepts in physical geography through interactive learning activities in an online geo-ICT environment

    Science.gov (United States)

    Verstraeten, Gert; Steegen, An; Martens, Lotte

    2016-04-01

    The increasing number of geospatial datasets and free online geo-ICT tools offers new opportunities for education in Earth Sciences. Geospatial technology indeed provides an environment through which interactive learning can be introduced in Earth Sciences curricula. However, the effectiveness of such e-learning approaches in terms of learning outcomes has rarely been addressed. Here, we present our experience with the implementation of digital interactive learning activities within an introductory Physical Geography course attended by 90 undergraduate students in Geography, Geology, Biology and Archaeology. Two traditional lectures were replaced by interactive sessions (each 2 h) in a flexible classroom where students had to work both in team and individually in order to explore some key concepts through the integrated use of geospatial data within Google EarthTM. A first interactive lesson dealt with the classification of river systems and aimed to examine the conditions under which rivers tend to meander or to develop a braided pattern. Students were required to collect properties of rivers (river channel pattern, channel slope, climate, discharge, lithology, vegetation, etc). All these data are available on a global scale and have been added as separate map layers in Google EarthTM. Each student collected data for at least two rivers and added this information to a Google Drive Spreadsheet accessible to the entire group. This resulted in a database of more than one hundred rivers spread over various environments worldwide. In a second phase small groups of students discussed the potential relationships between river channel pattern and its controlling factors. Afterwards, the findings of each discussion group were presented to the entire audience. The same set-up was followed in a second interactive session to explore spatial variations in ecosystem properties such as net primary production and soil carbon content. The qualitative evaluation of both interactive

  17. Surgical double valve replacement after transcatheter aortic valve implantation and interventional mitral valve repair.

    Science.gov (United States)

    Wendeborn, Jens; Donndorf, Peter; Westphal, Bernd; Steinhoff, Gustav

    2013-11-01

    Transcatheter aortic valve implantation, as well as interventional mitral valve repair, offer reasonable therapeutic options for high-risk surgical patients. We report a rare case of early post-interventional aortic valve prosthesis migration to the left ventricular outflow tract, with paravalvular leakage and causing severe mitral valve regurgitation. Initial successful interventional mitral valve repair using a clipped edge-to-edge technique revealed, in a subsequent procedure, the recurrence of mitral valve regurgitation leading to progressive heart failure and necessitating subsequent surgical aortic and mitral valve replacement.

  18. A low power, on demand electrothermal valve for wireless drug delivery applications.

    Science.gov (United States)

    Li, Po-Ying; Givrad, Tina K; Sheybani, Roya; Holschneider, Daniel P; Maarek, Jean-Michel I; Meng, Ellis

    2010-01-01

    We present a low power, on demand Parylene MEMS electrothermal valve. A novel Omega-shaped thermal resistive element requires low power (approximately mW) and enables rapid valve opening (approximately ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated.

  19. Mitral Valve Disease

    Science.gov (United States)

    ... for more information on procedures, news, and pre- & post-operative care. Section Navigation Select Topic Aortic Valve Disease ... is most commonly caused by inflammation from rheumatic fever, a disease that is related to strep infections; ...

  20. Valve Repair or Replacement

    Science.gov (United States)

    ... valve surgery can be done using a robot. Robotic surgery does not require a large incision in the ... The Texas Heart Institute has a robot. With robotic surgery, the surgeon has a control console, a side ...

  1. Pulmonary valve stenosis

    Science.gov (United States)

    ... valvuloplasty - pulmonary Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  2. Mitral valve regurgitation

    Science.gov (United States)

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ...

  3. Mitral Valve Prolapse

    Science.gov (United States)

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  4. Tgfβ-Smad and MAPK signaling mediate scleraxis and proteoglycan expression in heart valves.

    Science.gov (United States)

    Barnette, Damien N; Hulin, Alexia; Ahmed, A S Ishtiaq; Colige, Alain C; Azhar, Mohamad; Lincoln, Joy

    2013-12-01

    Mature heart valves are complex structures consisting of three highly organized extracellular matrix layers primarily composed of collagens, proteoglycans and elastin. Collectively, these diverse matrix components provide all the necessary biomechanical properties for valve function throughout life. In contrast to healthy valves, myxomatous valve disease is the most common cause of mitral valve prolapse in the human population and is characterized by an abnormal abundance of proteoglycans within the valve tri-laminar structure. Despite the clinical significance, the etiology of this phenotype is not known. Scleraxis (Scx) is a basic-helix-loop-helix transcription factor that we previously showed to be required for establishing heart valve structure during remodeling stages of valvulogenesis. In this study, we report that remodeling heart valves from Scx null mice express decreased levels of proteoglycans, particularly chondroitin sulfate proteoglycans (CSPGs), while overexpression in embryonic avian valve precursor cells and adult porcine valve interstitial cells increases CSPGs. Using these systems we further identify that Scx is positively regulated by canonical Tgfβ2 signaling during this process and this is attenuated by MAPK activity. Finally, we show that Scx is increased in myxomatous valves from human patients and mouse models, and overexpression in human mitral valve interstitial cells modestly increases proteoglycan expression consistent with myxomatous mitral valve phenotypes. Together, these studies identify an important role for Scx in regulating proteoglycans in embryonic and mature valve cells and suggest that imbalanced regulation could influence myxomatous pathogenesis.

  5. Valves replacement operation in treatment of electrical storm induced by rheumatic valves disease

    Institute of Scientific and Technical Information of China (English)

    Zhenqiang Chen; Hui Zhang; Yang Zhao; Haiji Yang; Sheng'ai Ye; Liang Cheng; Ying Zhang

    2007-01-01

    Objective: To present a case of electrical storm (ES) in a female patient with rheumatic valve disease. Methods: A female patient with severe rheumatic valve disease suffered an unexpected ES. She received more than 50 electrical shocks for repeated cardiac arrests due to ES over 16 hours. Then she received beta-blocking agent treatment and had an operation of double valves replacement. Results: ES was suppressed by sympathetic blockade with beta-receptor blocker and finally disappeared after the double pathological valves had been replaced. Conclusion: Increased sympathetic activity plays an important role in the genesis of electrical storm and sympathetic blockade may effectively suppress ES. However, the most important thing in the treatment of ES is to identify and eliminate the underlying cause of ES.

  6. Pre-clinical In Vitro and In Vivo Models for Heart Valve Therapies.

    Science.gov (United States)

    Taramasso, Maurizio; Emmert, Maximilian Y; Reser, Diana; Guidotti, Andrea; Cesarovic, Nikola; Campagnol, Marino; Addis, Alessandro; Nietlispach, Fabian; Hoerstrup, Simon P; Maisano, Francesco

    2015-07-01

    Heart valve disease is a frequently encountered pathology, related to high morbidity and mortality rates. Animal models are interesting to investigate the causality but also underlying mechanisms and potential treatments of human heart valve diseases. Strongly believing that both in vivo and ex vivo models are fundamental to support research and development of new technologies, we here report some examples of heart valve disease models, which in our experience have been actively used to support the development of new valve therapies.

  7. [Technologies for cardiac valve prostheses].

    Science.gov (United States)

    Nakano, Kiyoharu

    2009-07-01

    To show the technological development of cardiac valve prostheses, a historical review of both mechanical and biological valve prostheses and a current overview of modern cardiac valve devices are provided. Scince the 1st implantation of Starr-Edwards ball valve in 1960, both mechanical and biological valve prostheses have advanced. The valve design, the material of the leaflet and the hausing of mechanical prostheses have improved. Currently, the majority of the mechanical prostheses are bileaflet tilting disc valves made of pyrolytic carbon, which is antithromboembolic. However, anticoagulation therapy with warfarin is still required. As for the bioprostheses, although the fixation and anti-mineralization methods of the tissues improved, the durability of these valves is still limited. For the material of the current biological valves, the porcine aortic valve or bovine pericardium are used. The tissues are fixed by non-pressure or low-pressure method in glutaraldehyde solution. A stented and non-stented valves are available. Epoch-making events in this field are the implantation of new bioprosthetic valves using tissue engineering methods and the development of the transcatheter valve replacement therapies.

  8. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen;

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry.......Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  9. Active and Reserve Unit Costs: DOD Report to Congress Generally Addressed the Statutory Requirements but Lacks Detail

    Science.gov (United States)

    2014-07-31

    National Defense Authorization Act for Fiscal Year 2012, Section 1080A, issued in January 2012, states that such reductions must be balanced with...preparation for future challenges and protection of the broad range of U.S. national security interests. One key to achieving this balance is determining the...addressed the statutory requirements, we used a scorecard methodology in which two analysts independently assessed the extent to which the report’s

  10. Mitral Valve Aneurysm: A Rare Complication of Aortic Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    A Moaref

    2008-11-01

    Full Text Available A 20-year-old intravenous drug abuser man, refered to our hospital with dyspnea and orthopnea. Tranesophagealechocardiography revealed severe aortic regurgitation, healed vegetation of aortic valve and an aneurysm of theanterior leaflet of the mitral valve. The patient was discharged after aortic valve replacement and mitral valverepair.

  11. Research on Valve Body Design of Large Bore Sodium Valve

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Large bore sodium valve is one kind of key equipments of China Demonstration Fast Reactor (CDFR). It is installed in the pipeline before and behind SG units as a locking mechanism. Valve body which is used to bear pressure is the core of sodium valve design.

  12. Reduction of calcification by various treatments in cardiac valves.

    Science.gov (United States)

    Rao, K P; Shanthi, C

    1999-01-01

    The importance of glutaraldehyde pretreated bioprosthetic heart valves fabricated from bovine pericardium or porcine aortic valves is well realized in the management of valvular heart diseases. But, calcification limits the durability and is the most frequent cause of failure of these bioprosthetic heart valves. Various research groups in the world are actively involved in describing, understanding, and preventing calcification of bioprosthetic heart valves. Since there is no satisfactory clinical means for preventing or treating this disorder, attempts are made to improve the anticalcification properties of the replacement valves in the preparation stage itself. Research in this area is very active, and many newer approaches are made to mitigate the problem. An attempt has been made in the present article to review various theories put forward to explain the causative factors involved and mechanistic aspects of biocalcification and to present various strategies attempted for the prevention of calcification with the special feature on the work done in the area in our laboratory.

  13. Minimising life cycle costs of automated valves in offshore platforms

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Petays, Juha [Metso Automation do Brasil Ltda., Rio de Janeiro, RJ (Brazil); Niemela, Ismo [Metso Automation, Imatra (Finland)

    2012-07-01

    Automated process valves play an essential role in offshore platforms operation. If you are able to optimize their operation and maintenance activities you can receive extensive operational savings with minimal investment. Valves used in offshore platforms doesn't differentiate that much from the valves used in downstream but there are certain specialties, which makes the operations more challenging in offshore: Process valves are more difficult to access and maintain because of space limitations. Also spare part inventories and deliveries are challenging because of offshore platform's remote location. To overcome these challenges usage of digital positioners with diagnostic features has become more common because predictive maintenance capabilities enable possibilities to plan the maintenance activities and this way optimise the spare part orders regarding to valves. There are intelligent controllers available for control valves, automated on/off valves as well as ESD-valves and whole network of automated valves on platforms can be controlled by intelligent valve controllers. This creates many new opportunities in regards of optimized process performance or predictive maintenance point-of-view. By means of intelligent valve controllers and predictive diagnostics, condition monitoring and maintenance planning can also be performed remotely from an onshore location. Thus, intelligent valve controllers provide good way to minimize spending related to total cost of ownership of automated process valves. When purchase value of control valve represent 20% of TCO, intelligent positioner and predictive maintenance methods can enable as high as 30% savings over the life cycle of asset so basically it benefit savings higher than whole investment of monitored asset over its life cycle. This is mainly achieved through the optimized maintenance activities since real life examples has shown that with time based maintenance (preventive maintenance) approach 70% of

  14. Transcatheter Aortic Heart Valve Thrombosis

    DEFF Research Database (Denmark)

    Hansson, Nicolaj C; Grove, Erik L; Andersen, Henning R;

    2016-01-01

    BACKGROUND: There is increasing focus on transcatheter heart valve (THV) thrombosis. However, there are limited data on incidence, clinical implications and predisposing factors of THV thrombosis following transcatheter aortic valve replacement (TAVR). OBJECTIVES: We assessed the incidence...

  15. Safety valve for offshore borehole

    Energy Technology Data Exchange (ETDEWEB)

    McGill, H.L.; Randermann, E. Jr.; Musik, O.J.

    1977-10-06

    The invention concerns a new and improved submarine safety valve with a valve element which rotate, which can be used, in emergencies, to separate the wound-up piping which extends into the borehole and to close the production line.

  16. Nasal valve surgery.

    Science.gov (United States)

    Apaydin, Fazil

    2011-04-01

    Nasal obstruction can be due to internal and external valve problems that can be seen before and after rhinoplasty. The main scope of this article is to concentrate on surgical solutions to these problems. To overcome nasal obstruction at the internal valve, spreader grafts, spreader flaps, upper lateral splay graft, butterfly graft, flaring suture, M-plasty, Z-plasty, and suspension sutures have been described. The management of the external valve problems is possible by using lateral crural dissection and repositioning, lateral crural strut grafts, alar battens, lateral crural turn-in flap, alar rim grafts, and various other methods. It is not easy to decide which techniques would work best in every case. After a thorough examination and analysis, the underlying cause of the nasal obstruction can be understood, and one or multiple procedures can be chosen according to each individual problem.

  17. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  18. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly...... resulted from collision or effusion. A static tower has been applied for the main core of this part of the valve which loses balance state under the effect of collision and bounces to the neighboring part, which results in release of the catch and blockage of the gas passing channel....

  19. Pulsatile prosthetic valve flows.

    Science.gov (United States)

    Phillips, W M; Snyder, A; Alchas, P; Rosenberg, G; Pierce, W S

    1980-01-01

    The laser Doppler system has been established as a useful tool for eliciting the properties of simulated cardiovascular flows, and thus for comparative studies of flow properties of prosthetic valves. Significant differences among valve types and between models of one type have been documented. The complex variations of velocity profiles with time show that comparisons must be made for unsteady pulsatile rather than steady flow, despite the volume and complexity of the data required. Future studies will include methods of compacting the data presentation and improving the details of the experimental stimulation.

  20. Valve stem and packing assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wordin, J.J.

    1990-12-31

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele`s pivot. The Schiele`s pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele`s pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele`s pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  1. Transcatheter Valve-in-Valve: A Cautionary Tale.

    Science.gov (United States)

    Luc, Jessica G Y; Shanks, Miriam; Tyrrell, Benjamin D; Welsh, Robert C; Butler, Craig R; Meyer, Steven R

    2016-09-01

    Transcatheter aortic valve replacement (TAVR) by valve-in-valve (VIV) implantation is an alternative treatment for high-risk patients with a degenerating aortic bioprosthesis. We present a case of transapical TAVR VIV with a 29-mm Edwards SAPIEN XT (ESV) (Edwards Lifesciences, Irvine, CA) into a 29-mm Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) in which unanticipated dilatation of the Freestyle bioprosthesis resulted in intraprocedural embolization of the TAVR valve, necessitating urgent conversion to a conventional surgical aortic valve replacement (AVR). Our experience suggests that TAVR VIV with the 29-mm ESV in the setting of a degenerated 29-mm Freestyle stentless bioprosthesis must be undertaken with caution.

  2. Prosthetic valve thrombosis in a patient with mitral valve replacement.

    Science.gov (United States)

    Bilal, Muhammad; Khan, Muhammad Shahzeb; Haseeb, Abdul; Khan, Abdul Bari

    2015-07-01

    Prosthetic valve thrombosis within one year after mitral valve replacement is rarely seen in patients on warfarin therapy and without any risk factor. Here, we describe a case of a 39-year- old female, who presented with dyspnoea and shortness of breath 11 months after mitral valve replacement. The echocardiogram revealed severe valvular stenosis due to presence of clots on the mitral valve and restricted motion of the mitral leaflets. As a result of deterioration of general condition and haemodynamic un-stability, plan was made to re-operate for her valve replacement surgery. This case report highlights the diagnosis, prevention and management of patients with prosthetic valve thrombosis following mitral valve replacement.

  3. Transhepatic implant of a trimmed Melody™ valved stent in tricuspid position in a 1-year-old infant.

    Science.gov (United States)

    Cools, Bjorn; Rega, Filip; Gewillig, Marc

    2017-02-15

    Percutaneous valved stent implantation is precluded in small infants because large delivery sheaths and large devices. We describe a procedure in a 1-year-old boy in whom a 19 mm Epic™ valve in tricuspid position had become dysfunctional. As the internal diameter of the prosthetic valve was about 16 mm, the only available valve was the Melody™ valved stent. Technical modifications were required to address issues like venous access, the bulky delivery system, and the length of the valved stent. The Melody™ valved stent was surgically trimmed and mounted on a 16 mm Tyshak balloon, access was provided transhepatically through a short 18 Fr sheath. After deployment, the intrahepatic route was sealed with two vascular plugs (8 and 10 mm) in tandem. The procedure was uncomplicated with perfect valve function 18 months after implant. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. Distortion of the CoreValve during transcatheter aortic valve-in-valve implantation due to valve dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Souteyrand, Geraud, E-mail: gsouteyrand@chu-clermontferrand.fr [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Wilczek, Krzysztof [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Innorta, Andrea; Camilleri, Lionel [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Chodor, Piotr [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Lusson, Jean-René; Motreff, Pascal [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Laborde, Jean-Claude [St. George' s Hospital, London (United Kingdom); Chabrot, Pascal; Durel, Nicolas [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France)

    2013-09-15

    Nowadays transcatheter aortic valve implantation (TAVI) is an accepted alternative to surgical aortic valve replacement for high-risk patients (pts). Successful TAVI procedures for failed aortic surgical bioprosthesis (TAV-in-SAV) have already been reported. In the presented two cases of TAV-in-SAV implantation a strut distortion of the stent was revealed on angiographic imaging and confirmed on control CT scan. In both procedures, a dislocation of the medtronic core valve (MCV) prosthesis during implantation led to valve retrieval, with a necessity of reloading it in the 18F introducer before subsequent implantation of the same valve in correct position.

  5. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J.; Ansanelli, E.

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  6. Heart valve surgery - discharge

    Science.gov (United States)

    ... ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  7. Aortic valve surgery - open

    Science.gov (United States)

    ... Saunders; 2012:chap 61. Otton CM, Bowow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  8. Vent Relief Valve Test

    Science.gov (United States)

    2008-01-01

    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  9. Measurement of reed valve kinematics

    Directory of Open Access Journals (Sweden)

    Fenkl Michael

    2016-01-01

    Full Text Available The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  10. Measurement of reed valve kinematics

    Science.gov (United States)

    Fenkl, Michael; Dvořák, Václav; Vít, Tomáš

    2016-03-01

    The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  11. Surgical treatment of infective endocarditis with aortic and tricuspid valve involvement using cryopreserved aortic and mitral valve allografts.

    Science.gov (United States)

    Ostrovsky, Yury; Spirydonau, Siarhei; Shchatsinka, Mikalai; Shket, Aliaksandr

    2015-05-01

    Surgical treatment of infective and prosthetic endocarditis using allografts gives good results. Aortic allograft implantation is a common technique, while tricuspid valve replacement with a mitral allograft is very rare. Multiple valve disease in case of infective endocarditis is a surgical challenge as such patients are usually in a grave condition and results of surgical treatment are often unsatisfactory. In this article we describe a clinical case of successful surgical treatment in a patient with active infective endocarditis of aortic and tricuspid valve, complicated by an aortic-right ventricular fistula. The aortic valve and ascending aorta were replaced with a cryopreserved aortic allograft; the tricuspid valve was replaced with a cryopreserved mitral allograft. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  12. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    Science.gov (United States)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  13. High Temperature, High Frequency Fuel Metering Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Active Signal Technologies and its subcontractor Moog propose to develop a high-frequency actuator driven valve intended to achieve TRL 6 by the end of Phase II....

  14. The Activities and Impact of State Programs to Address Hereditary Breast and Ovarian Cancer, 2011–2014

    Directory of Open Access Journals (Sweden)

    Katrina F. Trivers

    2015-10-01

    Full Text Available In 2011, the Division of Cancer Prevention and Control (DCPC, at the United States Centers for Disease Control and Prevention (CDC, released a three-year funding opportunity announcement (FOA for a competitive, non-research cooperative agreement. The agreement enhanced the capacities of state health departments to promote the application of best practices for evidence-based breast cancer genomics through education, surveillance, and policy activities. The FOA required that applicants focus on activities related to hereditary breast and ovarian cancer (HBOC. The DCPC funded three states: Georgia, Michigan, and Oregon. Georgia was a first-time recipient of cancer genomics funding, whereas Michigan and Oregon had long standing activities in cancer genomics and had received CDC funding in the past. By the end of the funding period, each state had well-functioning and impactful state-based programs in breast cancer genomics. This article highlights the impact of a few key state activities by using CDC’s Science Impact Framework. There were challenges to implementing public health genomics programs, including the need to develop relevant partnerships, the highly technical nature of the subject matter, a lack of genetic services in certain areas, and the difficulty in funding genetic services. Georgia, Michigan, and Oregon have served as models for others interested in initiating or expanding cancer genomics programs, and they helped to determine what works well for promoting and integrating public health genomics into existing systems.

  15. Positioning Australia's Contemporary Health and Physical Education Curriculum to Address Poor Physical Activity Participation Rates by Adolescent Girls

    Science.gov (United States)

    Usher, Wayne; Edwards, Allan; Cudmore, Laura

    2016-01-01

    Background: Given the wealth of research identifying how schools are in a strong position to promote physical activity (PA) among children, it would be reasonable to suggest that initial experiences of physical education and school sport are critical factors influencing whether a student will develop a healthy relationship to PA. However, research…

  16. Trends in scientific activity addressing transmissible spongiform encephalopathies: a bibliometric study covering the period 1973–2002

    Directory of Open Access Journals (Sweden)

    Iribarren-Maestro Isabel

    2006-10-01

    Full Text Available Abstract Background The purpose of this study is to analyse the trends in scientific research on transmissible spongiform encephalopathies by applying bibliometric tools to the scientific literature published between 1973 and 2002. Methods The data for the study were obtained from Medline database, in order to determine the volume of scientific output in the above period, the countries involved, the type of document and the trends in the subject matters addressed. The period 1973–2002 was divided in three sub-periods. Results We observed a significant growth in scientific production. The percentage of increase is 871.7 from 1973 to 2002. This is more evident since 1991 and particularly in the 1996–2001 period. The countries found to have the highest output were the United States, the United Kingdom, Japan, France and Germany. The evolution in the subject matters was almost constant in the three sub-periods in which the study was divided. In the first and second sub-periods, the subject matters of greatest interest were more general, i.e Nervous system or Nervous system diseases, Creutzfeldt-Jakob disease, Scrapie, and Chemicals and Drugs, but in the last sub-period, some changes were observed because the Prion-related matters had the greatest presence. Collaboration among authors is small from 1973 to 1992, but increases notably in the third sub-period, and also the number of authors and clusters formed. Some of the authors, like Gajdusek or Prusiner, appear in the whole period. Conclusion The study reveals a very high increase in scientific production. It is related also with the beginnings of research on bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease, with the establishment of progressive collaboration relationships and a reflection of public health concerns about this problem.

  17. Percutaneous tricuspid valve replacement in childhood

    Directory of Open Access Journals (Sweden)

    Mathias Emmel

    2015-01-01

    Full Text Available Percutaneous replacement of the tricuspid valve with a bovine jugular venous valve (melody valve was successfully undertaken in a 9-year-old boy. The patient had a previous history of bacterial endocarditis of the native tricuspid valve in infancy. Initially, a pericardial patch valve was created, followed by surgical replacement of the valve using a biological tissue valve at 4 years of age. Progressive stenosis and regurgitation of the biological valve, with severe venous congestion and resulting hepatic dysfunction prompted percutaneous valve replacement.

  18. Addressing reverse inference in psychiatric neuroimaging: Meta‐analyses of task‐related brain activation in common mental disorders

    Science.gov (United States)

    Sprooten, Emma; Rasgon, Alexander; Goodman, Morgan; Carlin, Ariella; Leibu, Evan; Lee, Won Hee

    2017-01-01

    Abstract Functional magnetic resonance imaging (fMRI) studies in psychiatry use various tasks to identify case‐control differences in the patterns of task‐related brain activation. Differently activated regions are often ascribed disorder‐specific functions in an attempt to link disease expression and brain function. We undertook a systematic meta‐analysis of data from task‐fMRI studies to examine the effect of diagnosis and study design on the spatial distribution and direction of case‐control differences on brain activation. We mapped to atlas regions coordinates of case‐control differences derived from 537 task‐fMRI studies in schizophrenia, bipolar disorder, major depressive disorder, anxiety disorders, and obsessive compulsive disorder comprising observations derived from 21,427 participants. The fMRI tasks were classified according to the Research Domain Criteria (RDoC). We investigated whether diagnosis, RDoC domain or construct and use of regions‐of‐interest or whole‐brain analyses influenced the neuroanatomical pattern of results. When considering all primary studies, we found an effect of diagnosis for the amygdala and caudate nucleus and an effect of RDoC domains and constructs for the amygdala, hippocampus, putamen and nucleus accumbens. In contrast, whole‐brain studies did not identify any significant effect of diagnosis or RDoC domain or construct. These results resonate with prior reports of common brain structural and genetic underpinnings across these disorders and caution against attributing undue specificity to brain functional changes when forming explanatory models of psychiatric disorders. Hum Brain Mapp 38:1846–1864, 2017. © 2017 Wiley Periodicals, Inc. PMID:28067006

  19. Tricuspid Valve Replacement, Mechnical vs. Biological Valve, Which Is Better?

    Directory of Open Access Journals (Sweden)

    Haitham Akram Altaani

    2013-06-01

    Full Text Available Background: The initial trial in tricuspid surgery is repair; however, replacement is done whenever the valve is badly diseased. Tricuspid valve replacement comprises 1.7% of all tricuspid valve surgeries. Materials and Methods: The present retrospective study was performed using the medical records of 21 cases who underwent tricuspid valve replacement from January 2002 until the end of December 2010. The mean age of the participants was 52.3±8.8 years and 66.7% were females. In addition, tricuspid valve replacement was associated with mitral valve surgery, aortic valve surgery, and both in 14.3%, 4.8%, and 33.3% of the cases, respectively. Yet, isolated tricuspid valve replacement and redo surgery were performed in 10 cases (47.6% and 8 cases (38.1%, respectively. Besides, trial of repair was done in 14 cases (66.7%. Moreover, biological and mechanical valves were used in 76.2% and 23.8% of the patients, respectively. Results: According to the results, early mortality was 23.8% and one year survival was 66.7%. Moreover, early mortality was caused by right ventricular failure, multiorgan failure, medistinitis, and intracerbral bleeding in 42%, 28.6%, 14.3%, and 14.3% of the cases, respectively. In addition, 57.1% of the deaths had occurred in the cases where the biological valve was used, while 42.9% of the deaths had taken place where the mechanical one was utilized. Conclusions: The patients who require tricuspid valve replacement are usually high risk surgical candidates with early and long term mortality. The findings of the current study showed no significant hemodynamic difference between mechanical and biological valves.

  20. A model for meteoritic and lunar 40Ar/39Ar age spectra: Addressing the conundrum of multi-activation energies

    Science.gov (United States)

    Boehnke, P.; Harrison, T. Mark; Heizler, M. T.; Warren, P. H.

    2016-11-01

    Results of whole-rock 40Ar/39Ar step-heating analyses of extra-terrestrial materials have been used to constrain the timing of impacts in the inner solar system, solidification of the lunar magma ocean, and development of planetary magnetic fields. Despite the importance of understanding these events, the samples we have in hand are non-ideal due to mixed provenance, isotopic disturbances from potentially multiple heating episodes, and laboratory artifacts such as nuclear recoil. Although models to quantitatively assess multi-domain, diffusive 40Ar* loss have long been applied to terrestrial samples, their use on extra-terrestrial materials has been limited. Here we introduce a multi-activation energy, multi-diffusion domain model and apply it to 40Ar/39Ar temperature-cycling, step-heating data for meteoritic and lunar samples. We show that age spectra of extra-terrestrial materials, the Jilin chondrite (K-4) and Apollo 16 lunar breccia (67514 , 43), yielding seemingly non-ideal behavior commonly interpreted as either laboratory artifacts or localized shock heating of pyroxene, are meaningful and can be understood in context of the presence of multi-diffusion domains containing multiple activation energies. Internally consistent results from both the meteoritic and lunar samples reveal high-temperature/short duration thermal episodes we interpret as due to moderate shock heating.

  1. Transcatheter Replacement of Failed Bioprosthetic Valves

    DEFF Research Database (Denmark)

    Simonato, Matheus; Webb, John; Kornowski, Ran

    2016-01-01

    Background-Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets fo...

  2. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  3. "Vanishing" pulmonary valve stenosis

    Directory of Open Access Journals (Sweden)

    Nofil I Arain

    2012-01-01

    Full Text Available Objective: Both spontaneous resolution and progression of mild pulmonary valve stenosis (PS have been reported. We reviewed characteristics of the pulmonary valve (PV to determine factors that could influence resolution of mild PS. Methods: Fifteen asymptomatic pediatric patients with spontaneous resolution of isolated mild PS were retrospectively reviewed. Results: There was no correlation between the PV gradient, clinical presentation, age at diagnosis, or PV morphology. The PV annulus was small at initial presentation, which normalized at follow up. When corrected for the body surface area (z-score, the PV annulus was normal in all patients, including at initial evaluation. Conclusions: Based on our observation, neither age at diagnosis, nor PV-morphology-influenced resolution of mild PS. The variable clinical presentation makes it difficult to categorize and observe mild PS by auscultation alone. The PV annulus z-score could be a useful adjunct to determine the course and serial observation of mild PS.

  4. Replacement of outboard main steam isolation valves in a boiling water reactor plant

    Energy Technology Data Exchange (ETDEWEB)

    Schlereth, J.R.; Pennington, D.

    1996-12-01

    Most Boiling Water Reactor plants utilize wye pattern globe valves for main steam isolation valves for both inboard and outboard isolation. These valves have required a high degree of maintenance attention in order to pass the plant local leakage rate testing (LLRT) requirements at each outage. Northern States Power made a decision in 1993 to replace the outboard valves at it`s Monticello plant with double disc gate valves. The replacement of the outboard valves was completed during the fall outage in 1994. During the spring outage in April of 1996 the first LLRT testing was performed with excellent results. This presentation will address the decision process, time requirements and planning necessary to accomplish the task as well as the performance results and cost effectiveness of replacing these components.

  5. Resolving plant operational issues related to pressurizer safety relief valve piping

    Energy Technology Data Exchange (ETDEWEB)

    Bain, R.A. [Stone and Webster Engineering Corp., Boston, MA (United States). Mechanical Engineering Div.; Testa, M.F. [Duquesne Light Co., Shippingport, PA (United States). Mechanical Engineering Dept.

    1995-11-01

    Pressurizer safety and relief valve (PSARV) piping has many technical issues related to the qualification and operation of the system that have been addressed at Beaver Valley Unit 2. The PSARV piping is part of a system that must meet Code requirements while being subjected to very significant fluid transient loadings. Valve components include safety valves, power operated relief valves (PORVs), and motor operated block valves. Fluid slugs upstream of these valves can be steam or can be hot or cold water, resulting in a significant variance in possible slug densities. Problems with design options and hardware installed to decrease slug density such as heat tracing, and the susceptibility of the PORVs to leak are issues that affect plant operation, efficiency and cost effectiveness.

  6. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine

    2014-01-01

    IMPORTANCE: Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...

  7. Minimally Invasive Mitral Valve Replacement and Transfemoral Aortic Valve Implantation.

    Science.gov (United States)

    Rustenbach, Christian; Baumbach, Hardy; Hill, Stephan; Franke, Ulrich F W

    2015-01-01

    The case is reported of a symptomatic elderly patient with severe mitral regurgitation, severe aortic valve stenosis, and coronary heart disease. The coronary artery disease had been interventionally treated four years previously with stent implantation into the right coronary artery. Published studies have shown that a combination of mitral and aortic valve surgery is associated with a significantly increased risk of mortality and morbidity, particularly in elderly patients. In the present patient, both valvular malformations were successfully treated with a single-step interdisciplinary approach, namely an initial surgical mitral valve replacement followed by transfemoral transcatheter aortic valve replacement.

  8. Anterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Vidyadhar P. Mali

    2006-07-01

    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  9. Posterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Steve J. Hodges

    2009-01-01

    Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves[1].

  10. Supramolecular spin valves

    Science.gov (United States)

    Urdampilleta, M.; Klyatskaya, S.; Cleuziou, J.-P.; Ruben, M.; Wernsdorfer, W.

    2011-07-01

    Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc2 single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.

  11. Valve stem and packing assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wordin, J.J.

    1991-09-03

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

  12. Valve stem and packing assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wordin, John J. (Bingham County, ID)

    1991-01-01

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  13. Valve stem and packing assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wordin, J.J.

    1990-01-01

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  14. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  15. Mitral Valve Prolapse in Pregnancy

    Directory of Open Access Journals (Sweden)

    Shi-Min Yuan

    Full Text Available Abstract Mitral valve prolapse is a benign condition. Mitral regurgitation is only complicated in patients with severe mitral valve prolapse. Women with mitral valve prolapse in the absence of other cardiovascular disorders tolerate pregnancy well and do not develop remarkable cardiac complications. Nevertheless, serious complications of mitral valve prolapse, including arrhythmia, infective endocarditis and cerebral ischemic events, can be present in pregnancy. Debates remain with regard to the use of prophylactic antibiotics and β-blockers in the pregnant women with mitral valve prolapse. The prognosis of the pregnant patients might be closely related to the pathological and (or functional changes of the mitral valve. Non-myxomatous mitral valve prolapse poses no or little obstetric risks in terms of pregnancy, labor and neonatal complications; whereas myxomatous mitral valve prolapse is a major etiology of valvular heart disease in women of childbearing age. In the pregnant patients with mitral valve prolapse progressing into major complications, surgical interventions are considered. Medicinal treatment of such patients with β-blockers should be a concern for the fetal safety.

  16. Innovative Stemless Valve Eliminates Emissions

    Science.gov (United States)

    2008-01-01

    Big Horn Valve Inc. (BHVI), of Sheridan, Wyoming, won a series of SBIR and Small Business Technology Transfer (STTR) contracts with Kennedy Space Center and Marshall Space Flight Center to explore and develop a revolutionary valve technology. BHVI developed a low-mass, high-efficiency, leak-proof cryogenic valve using composites and exotic metals, and had no stem-actuator, few moving parts, with an overall cylindrical shape. The valve has been installed at a methane coal gas field, and future applications are expected to include in-flight refueling of military aircraft, high-volume gas delivery systems, petroleum refining, and in the nuclear industry.

  17. Whitey Gauge and Root Valves (VPS)

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.

    2000-09-03

    These valves are 1/2 inch ball valves fabricated of 316 stainless steel: Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the Vacuum Pumping and Helium System.

  18. Prognostics for Ground Support Systems: Case Study on Pneumatic Valves

    Science.gov (United States)

    Daigle, Matthew; Goebel, Kai

    2011-01-01

    Prognostics technologies determine the health (or damage) state of a component or sub-system, and make end of life (EOL) and remaining useful life (RUL) predictions. Such information enables system operators to make informed maintenance decisions and streamline operational and mission-level activities. We develop a model-based prognostics methodology for pneumatic valves used in ground support equipment for cryogenic propellant loading operations. These valves are used to control the flow of propellant, so failures may have a significant impact on launch availability. Therefore, correctly predicting when valves will fail enables timely maintenance that avoids launch delays and aborts. The approach utilizes mathematical models describing the underlying physics of valve degradation, and, employing the particle filtering algorithm for joint state-parameter estimation, determines the health state of the valve and the rate of damage progression, from which EOL and RUL predictions are made. We develop a prototype user interface for valve prognostics, and demonstrate the prognostics approach using historical pneumatic valve data from the Space Shuttle refueling system.

  19. Microfluidic droplet sorting using integrated bilayer micro-valves

    Science.gov (United States)

    Chen, Yuncong; Tian, Yang; Xu, Zhen; Wang, Xinran; Yu, Sicong; Dong, Liang

    2016-10-01

    This paper reports on a microfluidic device capable of sorting microfluidic droplets utilizing conventional bilayer pneumatic micro-valves as sorting controllers. The device consists of two micro-valves placed symmetrically on two sides of a sorting area, each on top of a branching channel at an inclined angle with respect to the main channel. Changes in transmitted light intensity, induced by varying light absorbance by each droplet, are used to divert the droplet from the sorting area into one of the three outlet channels. When no valve is activated, the droplet flows into the outlet channel in the direction of the main channel. When one of the valves is triggered, the flexible membrane of valve will first be deflected. Once the droplet leaves the detection point, the deflected membrane will immediately return to its default flattened position, thereby exerting a drawing pressure on the droplet and deviating it from its original streamline to the outlet on the same side as the valve. This sorting method will be particularly suitable for numerous large-scale integrated microfluidic systems, where pneumatic micro-valves are already used. Only few structural modifications are needed to achieve droplet sorting capabilities in these systems. Due to the mechanical nature of diverting energy applied to droplets, the proposed sorting method may induce only minimal interference to biological species or microorganisms encapsulated inside the droplets that may accompany electrical, optical and magnetic-based techniques.

  20. Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Disease

    DEFF Research Database (Denmark)

    Mylotte, Darren; Lefevre, Thierry; Søndergaard, Lars

    2014-01-01

    BACKGROUND: Limited information exists describing the results of transcatheter aortic valve (TAV) replacement in patients with bicuspid aortic valve (BAV) disease (TAV-in-BAV). OBJECTIVES: This study sought to evaluate clinical outcomes of a large cohort of patients undergoing TAV-in-BAV. METHODS...

  1. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H

    2015-01-01

    risk factors. METHODS AND RESULTS: Observational single-center study of 509 consecutive patients treated with a transcatheter implanted self-expandable aortic valve prosthesis (Medtronic CoreValve). We identified 18 patients diagnosed with TAVI-PVE during a median follow-up period of 1.4 years...

  2. Double orifice mitral valve: A case report

    Directory of Open Access Journals (Sweden)

    Musić Ljilja

    2016-01-01

    Full Text Available Introduction. Double orifice mitrol valve (DOMV is a very rare congenital heart defect. Case report. We reported 20-year-old male referred to our center due to evaluation of his cardiologic status. He was operated on shortly after birth for a tracheoesophageal fistula. Accidentally, echocardiography examination at the age of 4 years revealed double orifice mitral valve (DOMV without the presence of mitral regurgitation, as well as mitral stenosis, with normal dimensions of all cardiac chambers. The patient was asymptomatic, even more he was a kick boxer. His physical finding was normal. Electrocardiography showed regular sinus rhythm, incomplete right bundle branch block. Transthoracic echocardiography (TTE examination revealed the normal size of the left atrial, mitral leaflets were slightly more redundant. The left and right heart chambers, aorta, tricuspid valve and pulmonary artery valve were normal. During TTE examination on a short axis view two asymmetric mitral orifices were seen as a double mitral orifice through which we registered normal flow, without regurgitation and mitral stenosis. Transesophageal echocardiography (TEE examination from the transgastric view at the level of mitral valve, showed 2 single asymmetric mitral orifices separated by fibrous tissue, mitral leaflet with a separate insertion of hordes for each orifice. Conclusion. The presented patient with DOMV is the only one recognized in our country. The case is interesting because during 16-year a follow-up period there were no functional changes despite the fact that he performed very demanded sport activities. This is very important because there is no information in the literature about that.

  3. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid valves are subject to harsh exposure and actuators to drive these valves require robust performance and high reliability. DSM's piezoelectric...

  4. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    Science.gov (United States)

    Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Rivera, Andrew; Birdsell, Dawn N.; Wagner, David M.; Zenhausern, Frederic

    2015-12-01

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30-100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

  5. Surge-damping vacuum valve

    Science.gov (United States)

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  6. Mitral valve surgery - minimally invasive

    Science.gov (United States)

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  7. Valve-"Health"-Monitoring System

    Science.gov (United States)

    Jensen, Scott L.; Drouant, George J.

    2009-01-01

    A system that includes sensors and data acquisition, wireless data-communication, and data-processing subsystems has been developed as a means of both real-time and historical tracking of information indicative of deterioration in the mechanical integrity and performance of a highgeared ball valve or a linearly actuated valve that operates at a temperature between cryogenic and ambient.

  8. Combination throttle and shutoff valve

    Science.gov (United States)

    Carriker, J. W.

    1972-01-01

    Combination of translating sleeve throttle valve and conventional poppet valve provides capability of shutting off flow completely by poppet and sleeve control of the rate of flow. Integration of the two concepts can be accomplished without difficulty and in a manner that requires a minimum of development.

  9. Variable gas leak rate valve

    Energy Technology Data Exchange (ETDEWEB)

    Eernisse, Errol P. (Albuquerque, NM); Peterson, Gary D. (Albuquerque, NM)

    1976-01-01

    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  10. Low-power priority Address-Encoder and Reset-Decoder data-driven readout for Monolithic Active Pixel Sensors for tracker system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, P., E-mail: yangping0710@126.com [Central China Normal University, Wuhan (China); Aglieri, G.; Cavicchioli, C. [CERN, 1210 Geneva 23 (Switzerland); Chalmet, P.L. [MIND, Archamps (France); Chanlek, N. [Suranaree University of Technology, Nakhon Ratchasima (Thailand); Collu, A. [University of Cagliari, Cagliari (Italy); INFN (Italy); Gao, C. [Central China Normal University, Wuhan (China); Hillemanns, H.; Junique, A. [CERN, 1210 Geneva 23 (Switzerland); Kofarago, M. [CERN, 1210 Geneva 23 (Switzerland); University of Utrecht, Utrecht (Netherlands); Keil, M.; Kugathasan, T. [CERN, 1210 Geneva 23 (Switzerland); Kim, D. [Dongguk and Yonsei University, Seoul (Korea, Republic of); Kim, J. [Pusan National University, Busan (Korea, Republic of); Lattuca, A. [University of Torino, Torino (Italy); INFN (Italy); Marin Tobon, C.A. [CERN, 1210 Geneva 23 (Switzerland); Marras, D. [University of Cagliari, Cagliari (Italy); INFN (Italy); Mager, M.; Martinengo, P. [CERN, 1210 Geneva 23 (Switzerland); Mazza, G. [University of Torino, Torino (Italy); INFN (Italy); and others

    2015-06-11

    Active Pixel Sensors used in High Energy Particle Physics require low power consumption to reduce the detector material budget, low integration time to reduce the possibilities of pile-up and fast readout to improve the detector data capability. To satisfy these requirements, a novel Address-Encoder and Reset-Decoder (AERD) asynchronous circuit for a fast readout of a pixel matrix has been developed. The AERD data-driven readout architecture operates the address encoding and reset decoding based on an arbitration tree, and allows us to readout only the hit pixels. Compared to the traditional readout structure of the rolling shutter scheme in Monolithic Active Pixel Sensors (MAPS), AERD can achieve a low readout time and a low power consumption especially for low hit occupancies. The readout is controlled at the chip periphery with a signal synchronous with the clock, allows a good digital and analogue signal separation in the matrix and a reduction of the power consumption. The AERD circuit has been implemented in the TowerJazz 180 nm CMOS Imaging Sensor (CIS) process with full complementary CMOS logic in the pixel. It works at 10 MHz with a matrix height of 15 mm. The energy consumed to read out one pixel is around 72 pJ. A scheme to boost the readout speed to 40 MHz is also discussed. The sensor chip equipped with AERD has been produced and characterised. Test results including electrical beam measurement are presented.

  11. Allegheny County Address Points

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains address points which represent physical address locations assigned by the Allegheny County addressing authority. Data is updated by County...

  12. Allegheny County Address Points

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains address points which represent physical address locations assigned by the Allegheny County addressing authority. Data is updated by County...

  13. Fluid mechanics of artificial heart valves.

    Science.gov (United States)

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-02-01

    1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird's-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10-15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage.

  14. Cobalt reduction of NSSS valve hardfacings for ALARA

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joo Hak; Lee, Sang Sub [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-07-01

    This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author).

  15. Mitral Valve Surgery in Patients with Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Mahnoosh Foroughi

    2014-01-01

    Full Text Available Valvular heart disease is the common cardiac manifestation of systemic lupus erythematosus (SLE with a tendency for mitral valve regurgitation. In this study we report a case of mitral valve replacement for mitral stenosis caused by Libman-Sacks endocarditis in the setting of SLE. In addition, we provide a systematic review of the literature on mitral valve surgery in the presence of Libman-Sacks endocarditis because its challenge on surgical options continues. Surgical decision depends on structural involvement of mitral valve and presence of active lupus nephritis and antiphospholipid antibody syndrome. Review of the literature has also shown that outcome is good in most SLE patients who have undergone valvular surgery, but association of antiphospholipid antibody syndrome with SLE has negative impact on the outcome.

  16. Robotic mitral valve surgery.

    Science.gov (United States)

    Kypson, Alan P; Nifong, L Wiley; Chitwood, W Randolph

    2003-12-01

    A renaissance in cardiac surgery has begun. The early clinical experience with computer-enhanced telemanipulation systems outlines the limitations of this approach despite some procedural success. Technologic advancements, such as the use of nitinol U-clips (Coalescent Surgical Inc., Sunnyvale, CA) instead of sutures requiring manual knot tying, have been shown to decrease operative times significantly. It is expected that with further refinements and development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove to be beneficial for many patients. Robotic technology has provided benefits to cardiac surgery. With improved optics and instrumentation, incisions are smaller. The ergometric movements and simulated three-dimensional optics project hand-eye coordination for the surgeon. The placement of the wristlike articulations at the end of the instruments moves the pivoting action to the plane of the mitral annulus. This improves dexterity in tight spaces and allows for ambidextrous suture placement. Sutures can be placed more accurately because of tremor filtration and high-resolution video magnification. Furthermore, the robotic system may have potential as an educational tool. In the near future, surgical vision and training systems might be able to model most surgical procedures through immersive technology. Thus, a "flight simulator" concept emerges where surgeons may be able to practice and perform the operation without a patient. Already, effective curricula for training teams in robotic surgery exist. Nevertheless, certain constraints continue to limit the advancement to a totally endoscopic computer-enhanced mitral valve operation. The current size of the instruments, intrathoracic instrument collisions, and extrathoracic "elbow" conflicts still can limit dexterity. When smaller instruments are developed, these restraints may be resolved. Furthermore, a working port incision is still required for

  17. Valve-related complications after mechanical heart valve implantation.

    Science.gov (United States)

    Misawa, Yoshio

    2015-10-01

    The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7-3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4-1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

  18. Patents and heart valve surgery - II: tissue valves.

    Science.gov (United States)

    Cheema, Faisal H; Kossar, Alexander P; Rehman, Atiq; Younas, Fahad; Polvani, Gianluca

    2013-08-01

    Valvular heart disease affects millions of Americans yearly and currently requires surgical intervention to repair or replace the defective valves. Through a close-knit collaboration between physicians, scientists and biomedical engineers, a vast degree of research and development has been aimed towards the optimization of prosthetic heart valves. Although various methods have made fantastic strides in producing durable prostheses, the therapeutic efficacy of prosthetic valves is inherently limited by a dependency upon lifelong anticoagulant regimens for recipients - a difficult challenge for many in clinical setting. Thus, biological tissue valves have been developed to circumvent vascular and immunemediated complications by incorporating biological materials to mimic native valves while still maintaining a necessary level of structural integrity. Over the past decade, a multitude of patents pertaining to the refinement of designs as well as the advancement in methodologies and technologies associated with biological tissue valves have been issued. This review seeks to chronicle and characterize such patents in an effort to track the past, present, and future progress as well as project the trajectory of tissue valves in the years to come.

  19. PWR safety and relief valve test program. Valve selection/juftification report. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1982-12-01

    NUREG 0578 required that full-scale testing be performed on pressurizer safety valves and relief valves representative of those in use or planned for use in PWR plants. To obtain valve performance data for the entire population of PWR plant valves, nine safety valves and ten relief valves were selected as a fully representative set of test valves. Justification that the selected valves represent all PWR plant valves was provided by each safety and relief valve manufacturer. Both the valve selection and justification work was performed as part of the PWR Safety and Relief Valve Test Program conducted by EPRI on behalf of the PWR utilities in response to the recommendations of NUREG 0578 and the requirements of the NRC. Results of the Safety and Relief Valve Selection and Justification effort is documented in this report.

  20. Development and initial evaluation of a telephone-delivered, behavioral activation, and problem-solving treatment program to address functional goals of breast cancer survivors.

    Science.gov (United States)

    Lyons, Kathleen D; Hull, Jay G; Kaufman, Peter A; Li, Zhongze; Seville, Janette L; Ahles, Tim A; Kornblith, Alice B; Hegel, Mark T

    2015-01-01

    The purpose of this research was to develop and pilot test an intervention to optimize functional recovery for breast cancer survivors. Over two studies, 31 women enrolled in a goal-setting program via telephone. All eligible women enrolled (37% of those screened) and 66% completed all study activities. Completers were highly satisfied with the intervention, using it to address, on average, four different challenging activities. The longitudinal analysis showed a main effect of time for overall quality of life (F(5, 43.1) = 5.1, p = 0.001) and improvements in active coping (F (3, 31.7) = 4.9, p = 0.007), planning (F (3, 36.0) = 4.1, p = 0.01), reframing (F (3, 29.3) = 8.5, p < 0.001), and decreases in self-blame (F (3,31.6) = 4.3, p = 0.01). The intervention is feasible and warrants further study to determine its efficacy in fostering recovery and maximizing activity engagement after cancer treatment.

  1. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve.

    Science.gov (United States)

    Govindarajan, V; Udaykumar, H S; Herbertson, L H; Deutsch, S; Manning, K B; Chandran, K B

    2010-03-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase.

  2. 42 CFR 84.137 - Inhalation and exhalation valves; check valves; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Inhalation and exhalation valves; check valves... PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a) Inhalation and exhalation valves shall be provided where necessary and protected...

  3. Wear aspects of internal combustion engine valves

    Science.gov (United States)

    Panţuru, M.; Chicet, D.; Paulin, C.; Alexandru, A.; Munteanu, C.

    2016-08-01

    Because the surface engineering is becoming an increasingly viable alternative to the constructive changes made to improve the efficiency of internal combustion engines, have been proposed and tested various types of coatings of some organs of internal combustion engines. One vital organ is the engine valves, which is subjected during operation to combined thermal, mechanical, corrosion and wear solicitations, which are leading to severe corrosion and complete breakdown. In this paper were analyzed aspects of valves wear and the active surfaces were coated using the atmospheric plasma spraying method (APS) with two commercial powders: Ni-Al and YSZ. Microstructural analyzes were made on these layers and also observations regarding the possibility of using them as thermal barrier and anti-oxidant coatings.

  4. 49 CFR 195.116 - Valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 195.116 Section 195.116 Transportation... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to...

  5. 14 CFR 125.133 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 125.133 Section 125.133....133 Fuel valves. Each fuel valve must— (a) Comply with § 125.155; (b) Have positive stops or suitable... operation or from accelerated flight conditions are not transmitted to the lines connected to the valve....

  6. 49 CFR 192.145 - Valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 192.145 Section 192.145 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Design of Pipeline Components § 192.145 Valves. (a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API...

  7. 14 CFR 125.137 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  8. Cavitation guide for control valves

    Energy Technology Data Exchange (ETDEWEB)

    Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  9. Proportional valve with a piezoelectric actuator

    Science.gov (United States)

    Laski, Pawel Andrzej

    2016-11-01

    The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  10. Proportional valve with a piezoelectric actuator

    Directory of Open Access Journals (Sweden)

    Laski Pawel Andrzej

    2017-01-01

    Full Text Available The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  11. Double prosthetic aortic valve. Case report.

    Science.gov (United States)

    Liddicoat, J E; Bekassy, S M; De Bakey, M E

    1975-05-01

    A 55-year-old man underwent insection of a Hufnagel valve into his descending thoracic aorta for aortic valve insufficiency 18 years ago. He remained asymptomatic for 16 years. Because of progressive left ventricular failure his incompetent aortic valve was replaced with a De Bakey carbon ball aortic valve prosthesis 2 years later. Currently, 21 months after the operation, he is doing well with two aortic valves. Review of the literature suggests that he is the first patient reported with two aortic valves functioning concomitantly and one of the longest surviving patients with a Hufnagel valve.

  12. Pressure activated stability-bypass-control valves to increase the stable airflow range of a Mach 2.5 inlet with 40 percent internal contraction

    Science.gov (United States)

    Mitchell, G. A.; Sanders, B. W.

    1974-01-01

    The throat of a Mach 2.5 inlet with a coldpipe termination was fitted with a stability-bypass system. The inlet stable airflow range provided by various stability-bypass entrance configurations in alternate combination with several stability-bypass exit controls was determined for both steady-state conditions and internal transient pulses. Transient results were also obtained for the inlet with a choke point at the diffuser exit. Instart angles of attack were determined for the various stability-bypass entrance configurations. The response of the inlet-coldpipe system to internal and external oscillating disturbances was determined. Poppet valves at the stability-bypass exit provided an inlet stable airflow range of 28 percent or greater at all static and transient conditions.

  13. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Directory of Open Access Journals (Sweden)

    Harish Ramakrishna

    2015-01-01

    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  14. Compliant topology optimization for planar passive flap micro valve.

    Science.gov (United States)

    Yoon, Gil Ho

    2014-10-01

    This paper reports the compliant topology optimization for planar passive flap micro valve considering fluid-structure interaction with a monolithic approach. Although flap valve type check valve is easy to manufacture and use for the applications for Bio/Nano/MEMS, its structural optimization has been seldom conducted so far. The size of the Bio/Nano/MEMS devices becomes smaller and the simple straight type micro valve structure is required to be optimized considering fluid speed. To address this optimization problem, the structural topology optimization scheme which designs optimal topologies is applied for a flap type check valve structure. To consider the coupling effects of fluid domain and structural domain, the monolithic finite element approach is employed. In the new analysis approach, solid domain is simulated by introducing the inverse permeability in the Navier-Stokes equation and the fluid stress filter in the linear elasticity equation. Also it is a new idea that fluid domain is simulated by finite elements with a weak Young's modulus in the linear elasticity equation. The mutual couplings between fluid and structure are considered by the introduction of the deformation tensor which is one of the basic concepts of the continuum mechanism. By distributing material properties inside a design domain for compliant flap, optimal flap structures can be constructed with different fluid speeds. By investigating the optimal layouts of several passive flap designs, we prove that the structural topology optimization can provide optimal layouts for Bio, Nano, and MEMS applications.

  15. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  16. Valve performance concept move from preventive to condition-oriented maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Zanner, G.; Kradepohl, P.

    1996-12-01

    As a turnkey supplier of nuclear and fossil power plants, Siemens must pay attention in concentrating, maintaining, and developing the expertise in many areas such as system design, components, materials, quality assurance, and qualification testing within centralized organizations. In the company segment VALVES, Siemens/KWU is staffed with experienced professionals who have serviced the power plant industry for about 25 years. The valve engineers deal with all kinds of valve and actuator-related activities like design ratings, development, qualifications, and ongoing improvements. In this regard, the engineers are involved in nearly all actual problems and suggested solutions through continuing dialogues with utilities, authorities, and vendors of valves and actuators.

  17. Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, K.; Barnes, D.; Martin, R.H.; Rae, J.R. (Department of Diagnostic Radiology, Victoria General Hospital Halifax, Nova Scotia (Canada))

    1991-09-01

    A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess.

  18. Human tissue valves in aortic position: determinants of reoperation and valve regurgitation

    NARCIS (Netherlands)

    T.P. Willems (Tineke); E.W. Steyerberg (Ewout); V.E. Kleyburg-Linkers; E. Bos (Egbert); L.A. van Herwerden (Lex); J.R.T.C. Roelandt (Jos); J.J.M. Takkenberg (Hanneke)

    2001-01-01

    textabstractBACKGROUND: Human tissue valves for aortic valve replacement have a limited durability that is influenced by interrelated determinants. Hierarchical linear modeling was used to analyze the relation between these determinants of durability and valve

  19. Comparison of outcomes after aortic valve replacement with a mechanical valve or a bioprosthesis using microsimulation

    NARCIS (Netherlands)

    J.P.A. Puvimanasinghe (John); M.B. Edwards; M.J.C. Eijkemans (René); E.W. Steyerberg (Ewout); L.A. van Herwerden (Lex); K.M. Taylor; G.L. Grunkemeier (Gary); J.D.F. Habbema (Dik); A.J.J.C. Bogers (Ad); J.J.M. Takkenberg (Hanneke)

    2004-01-01

    textabstractBACKGROUND: Mechanical valves and bioprostheses are widely used for aortic valve replacement. Though previous randomised studies indicate that there is no important difference in outcome after implantation with either type of valve, knowledge of outcomes after aortic va

  20. Simpler valve for reciprocating engines

    Science.gov (United States)

    Akkerman, J. W.

    1978-01-01

    Simpler design eliminating camshafts, cams, and mechanical springs should improve reliability of hydrazine powered reciprocating engines. Valve is expected to improve efficiency, and reduce weight of engines in range up to 50 horsepower.

  1. Titanium in engine valve systems

    Energy Technology Data Exchange (ETDEWEB)

    Allison, J.E.; Sherman, A.M.; Bapna, M.R.

    1987-03-01

    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a two-to-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance.

  2. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  3. What Causes Heart Valve Disease?

    Science.gov (United States)

    ... a heart attack or injury to the heart. Rheumatic Fever Untreated strep throat or other infections with strep bacteria that progress to rheumatic fever can cause heart valve disease. When the body ...

  4. CONGENITAL QUADRICUSPID AORTIC-VALVE

    NARCIS (Netherlands)

    BROUWER, MHJ; DEGRAAF, JJ; EBELS, T

    1993-01-01

    Two patients with a quadricuspid aortic valve are described, one of them with concomitant juxtaposed coronary orifices facing the right hand facing sinus. The etiology and incidence of this congenital anomaly will be discussed.

  5. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy....... The 30-day mortality rate for the 98 patients was zero, although 14 of the 98 mini-sternotomies had to be converted to complete sternotomies intraoperatively due to technical problems. Such conversion doubled the operative time over that of the planned full sternotomies. In the group of patients whose...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  6. The spin-valve transistor

    NARCIS (Netherlands)

    Monsma, Douwe Johannes

    1998-01-01

    High density magnetic recording, magnetic random access memories, displacement and current detection, contactless switching and electronic compass applications all require magnetic field sensors with unprecedented sensitivity. The spin-valve effect (giant magnetoresistance) found in 1988 in magnetic

  7. 57. Aortic valve replacement with sutureless valve and mitral valve repair in patient with infected aortic homograft

    Directory of Open Access Journals (Sweden)

    A. attia

    2016-07-01

    Full Text Available The approach of implanting aortic sutureless valve inside the calcific homograft is suitable in redo surgery especially if associated with mitral valve surgery. Aortic valve replacement in patients who have undergone previous aortic root replacement with an aortic homograft remains a technical challenge because of homograft degeneration and the need for a redo Bentall operation. We report a case of redo aortic valve replacement (valve in valve with a sutureless valve and mitral valve repair by miniband annuloplasty in a female patient aged 64 years old who underwent aortic valve replacement with homograft 14 years ago and presented by sever aortic valve regurge and sever mitral valve regurge because of infective endocarditis. This technique allows rapid aortic valve replacement in a heavily calcified aortic root. It also avoids aortic valve size affection after mitral valve repair by ordinary methods especially in patients with small aortic annulus. This technique is particularly suitable in redo procedures for homograft degeneration, it avoids performing a redo Bentall operation with its known problems as well as to avoid patient prosthesis mismatch.

  8. DESIGN OF NOVEL HIGH PRESSURE- RESISTANT HYDROTHERMAL FLUID SAMPLE VALVE

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; YANG Canjun; WU Shijun; XIE Yingjun; CHEN Ying

    2008-01-01

    Sampling study is an effective exploration method, but the most extreme environments of hydrothermal vents pose considerable engineering challenges for sampling hydrothermal fluids. Moreover, traditional sampler systems with sample valves have difficulty in maintaining samples in situ pressure. However, decompression changes have effect on microorganisms sensitive to such stresses. To address the technical difficulty of collecting samples from hydrothermal vents, a new bidirectional high pressure-resistant sample valve with balanced poppet was designed. The sample valve utilizes a soft high performance plastic "PEEK" as poppet. The poppet with inapposite dimension is prone to occur to plastic deformation or rupture for high working pressure in experiments. To address this issue, based on the finite element model, simulated results on stress distribution of the poppet with different structure parameters and preload spring force were obtained. The static axial deformations on top of the poppet were experimented. The simulated results agree with the experimental results. The new sample valve seals well and it can withstand high working pressure.

  9. Reach Address Database (RAD)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Reach Address Database (RAD) stores the reach address of each Water Program feature that has been linked to the underlying surface water features (streams,...

  10. License Address List

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Address list generated from National Saltwater Angler Registry. Used in conjunction with an address-based sample as per survey design.

  11. Synthesizing Nanomaterials for Energy Applications: Probing Activity as a Function of Composition, Morphology and Purity to Address Key Issues Associated with Fuel Cells and Li-Ion Batteries

    Science.gov (United States)

    Scofield, Megan Elaine

    With the growing need to find alternative clean energy sources to fossil fuels, research into developing efficient fuel cells and batteries stands at the forefront of this grand effort. However, before mass commercialization, fundamental key issues need to be addressed. For example, fuel cells are subject to high catalyst costs and poor durability of the underlying carbon support. As a way to alleviate these issues, we have synthesized ultrathin one-dimensional (1D) alloy nanowires to probe the effect of composition, purity, and one-dimensionality upon the observed overall activity, performance, and durability. In terms of chemical composition, crystalline ultrathin PtM alloy nanowires (NWs) ('M' = Fe, Co, Ru, Cu, and Au) were generated and subsequently evaluated for the hydrogen oxidation reaction (HOR). Additionally, ternary-based catalysts were synthesized (PtRuFe) in order to analyze how chemical composition influences CO tolerance as well as methanol oxidation reaction (MOR) and formic acid oxidation reaction (FAOR) activities. In both cases, we utilized a sustainably mild, ambient wet-synthesis method for the fabrication of chemically pure and crystalline systems in order to fabricate ultrathin, homogeneous alloy NWs. Moreover, in these studies, our NW systems exhibit favorable synergistic electronic effects with respect to controls. To address another fundamental issue associated with the durability of fuel cells, we have synthesized various metal oxide and perovskite materials of different sizes and chemical compositions as supports for Pt nanoparticles (NPs). Specifically, we have demonstrated favorable metal support interactions between the Pt NPs and the SrRuO3 NP supports, which lead to increased MOR activity as compared with not only the other metal oxide supports tested but also the commercial Pt NP/C standard. In terms of Li-ion batteries, LiFePO4 materials have become increasingly popular as a cathode material due to the many benefits they possess

  12. The role of pygopus in the differentiation of intracardiac valves in Drosophila.

    Science.gov (United States)

    Tang, Min; Yuan, Wuzhou; Bodmer, Rolf; Wu, Xiushan; Ocorr, Karen

    2014-01-01

    Cardiac valves serve an important function; they support unidirectional blood flow and prevent blood regurgitation. Wnt signaling plays an important role in the formation of mouse cardiac valves and cardiac valve proliferation in Zebrafish, but identification of the specific signaling components involved has not been addressed systematically. Of the components involved in Wnt signal transduction, pygopus (pygo), first identified as a core component of Wnt signaling in Drosophila, has not yet to be investigated with respect to valve development and differentiation. Here, we take advantage of the Drosophila heart model to study the role of pygo in formation of valves between the cardiac chambers. We found that cardiac-specific pygo knockdown in the Drosophila heart causes dilation in the region of these cardiac valves, and their characteristic dense mesh of myofibrils does not form and resembles that of neighboring cardiomyocytes. In contrast, heart-specific knockdown of the transcription factors, arm/β-Cat, lgs/BCL9, or pan/TCF, which mediates canonical Wnt signal transduction, shows a much weaker valve differentiation defect. Double-heterozygous combinations of mutants for pygo and the Wnt-signaling components have no additional effect on heart function compared with pygo heterozygotes alone. These results are consistent with the idea that pygo functions independently of canonical Wnt signaling in the differentiation of the adult interchamber cardiac valves.

  13. Experimental study on the effect of an artificial cardiac valve on the left ventricular flow

    Science.gov (United States)

    Wang, JiangSheng; Gao, Qi; Wei, RunJie; Wang, JinJun

    2017-09-01

    The use of artificial valves to replace diseased human heart valves is currently the main solution to address the malfunctioning of these valves. However, the effect of artificial valves on the ventricular flow still needs to be understood in flow physics. The left ventricular flow downstream of a St. Jude Medical (SJM) bileaflet mechanical heart valve (BMHV), which is a widely implanted mechanical bileaflet valve, is investigated with time-resolved particle image velocimetry in the current work. A tilting-disk valve is installed on the aortic orifice to guarantee unidirectional flow. Several post-processing tools are applied to provide combined analyses of the physics involved in the ventricular flow. The triple jet pattern that is closely related to the characteristics of the bileaflet valve is discussed in detail from both Eulerian and Lagrangian views. The effects of large-scale vortices on the transportation of blood are revealed by the combined analysis of the tracking of Lagrangian coherent structures, the Eulerian monitoring of the shear stresses, and virtual dye visualization. It is found that the utilization of the SJM BMHV complicates the ventricular flow and could reduce the efficiency of blood transportation. In addition, the kinematics of the bileaflets is presented to explore the effects of flow structures on their motion. These combined analyses could elucidate the properties of SJM BMHV. Furthermore, they could provide new insights into the understanding of other complex blood flows.

  14. Bioprosthesis valve replacement in dogs with congenital tricuspid valve dysplasia: technique and outcome.

    Science.gov (United States)

    Arai, Shiori; Griffiths, Leigh G; Mama, Khursheed; Hackett, Timothy B; Monnet, Eric; Boon, June A; Carter, Leslie; Orton, E Christopher

    2011-06-01

    To describe the surgical technique and report outcome of dogs undergoing bioprosthesis valve replacement for severe tricuspid regurgitation (TR) secondary to congenital tricuspid valve dysplasia (TVD). Twelve client-owned dogs (19-43 kg) with TVD underwent tricuspid valve replacement with a bovine pericardial or porcine aortic bioprosthesis with the aid of cardiopulmonary bypass. Anticoagulation with warfarin was maintained for 3 months after surgery and then discontinued. Ten of 12 (83.3%) dogs survived surgery and were discharged from the hospital. Seven dogs were alive with complete resolution of TR for a median period of 48 months (range 1-66 months) after surgery. Two dogs underwent euthanasia because of bioprosthesis failure due to inflammatory pannus at 10 and 13 months after surgery. Two dogs experienced valve thrombosis that was resolved by tissue plasminogen activator. One dog developed suspected endocarditis after surgery that was resolved with antibiotics. Serious cardiac complications included atrial fibrillation and flutter, right-to-left shunt through an uncorrected patent foramen ovale, complete atrioventricular block, and sudden cardiac arrest. Postoperative atrial fibrillation or flutter did not occur in 7 dogs treated prophylactically with oral amiodarone before surgery. Curative intermediate-term outcomes are possible in dogs undergoing open tricuspid valve replacement with a bioprosthesis. Prosthesis-related complications include inflammatory pannus, thrombosis, and endocarditis. Postoperative atrial fibrillation or flutter can be reduced or prevented by prophylactic preoperative treatment with amiodarone. Several identified complications are avoidable or can be reduced with increased awareness and experience with these techniques. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Design of the Modular Pneumatic Valve Terminal

    Directory of Open Access Journals (Sweden)

    Jakub E. TAKOSOGLU

    2015-11-01

    Full Text Available The paper presents design of the modular pneumatic valve terminal, which was made on the basis of the patent application No A1 402905 „A valve for controlling fluid power drives, specially for pneumatic actuators, and the control system for fluid power drives valves”. The authors describe a method of operation of the system with double-acting valve and 5/2 (five ways and two position valve. Functions of the valve, and an example of application of the valve terminal in the production process were presented. 3D solid models of all the components of the valve were made. The paper presents a complete 3D model of the valve in various configurations. Using CAD-embedded SOLIDWORKS Flow Simulation computational fluid dynamics CFD analysis was also carried out of compressed air flow in the ways of the valve elements

  16. TCT-670 Optimal Transcatheter Heart Valve Sizing in Aortic Valve in Valve Implantation: Insights from the Valve in Valve International Data (VIVID) Registry

    DEFF Research Database (Denmark)

    Alnasser, Sami; Cheema, Asim N; Horlick, Eric

    2016-01-01

    Background: Optimal transcatheter heart valve (THV) sizing is crucial to optimize procedural outcomes. Larger THV oversizing is shown to decrease paravalvular leakage post transcatheter aortic valve replacement but its role in Valve in Valve implantation (ViV) is not well established. Methods...... group received a larger THV (25.5± 1.4 mm vs. 23.3 ± 1.0 mm, pimplantation, the oversized group achieved a larger EOA (1.54±0.4cm2 vs. 1.37± 0.5cm2, p...V implantation was associated with favorable post-implant EOA and gradient but a higher risk of aortic insufficiency and THV re-intervention. Further exploration within various THV and surgical valve types at different degree of THV oversizing is planned....

  17. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  18. Robotic excision of aortic valve papillary fibroelastoma and concomitant Maze procedure

    Directory of Open Access Journals (Sweden)

    Edward T Murphy

    2012-12-01

    Full Text Available Cardiothoracic surgeons have utilized the surgical robot to provide a minimally invasive approach to a number of intracardiac operations, including tumor resection, valve repair, and ablation of atrial arrhythmia. We report the case of a 58 year-old woman who was found to have a mobile mass on her aortic valve during evaluation of atrial fibrillation. Both of these conditions were addressed when she underwent a combined robotic biatrial Maze procedure and excision of the mass, which proved to be a papillary fibroelastoma of the aortic valve.

  19. LOFT pressurizer safety: relief valve reliability

    Energy Technology Data Exchange (ETDEWEB)

    Brown, E.S.

    1978-01-18

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  20. Current Status of Tissue Engineering Heart Valve.

    Science.gov (United States)

    Shinoka, Toshiharu; Miyachi, Hideki

    2016-11-01

    The development of surgically implantable heart valve prostheses has contributed to improved outcomes in patients with cardiovascular disease. However, there are drawbacks, such as risk of infection and lack of growth potential. Tissue-engineered heart valve (TEHV) holds great promise to address these drawbacks as the ideal TEHV is easily implanted, biocompatible, non-thrombogenic, durable, degradable, and ultimately remodels into native-like tissue. In general, three main components used in creating a tissue-engineered construct are (1) a scaffold material, (2) a cell type for seeding the scaffold, and (3) a subsequent remodeling process driven by cell accumulation and proliferation, and/or biochemical and mechanical signaling. Despite rapid progress in the field over the past decade, TEHVs have not been translated into clinical applications successfully. To successfully utilize TEHVs clinically, further elucidation of the mechanisms for TEHV remodeling and further translational research outcome evaluations will be required. Tissue engineering is a major breakthrough in cardiovascular medicine that holds amazing promise for the future of reconstructive surgical procedures. In this article, we review the history of regenerative medicine, advances in the field, and state-of-the-art in valvular tissue engineering. © The Author(s) 2016.

  1. High density 3D printed microfluidic valves, pumps, and multiplexers.

    Science.gov (United States)

    Gong, Hua; Woolley, Adam T; Nordin, Gregory P

    2016-07-07

    In this paper we demonstrate that 3D printing with a digital light processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv., 2015, 5, 106621), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics, 2015, 9, 016501), which were already the smallest that have been reported. Moreover, we show that incorporation of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability of 3D printed valves up to 1 million actuations. Using two valves and a valve-like displacement chamber (DC), we also create compact 3D printed pumps. With 5-phase actuation and a 15 ms phase interval, we obtain pump flow rates as high as 40 μL min(-1). We also characterize maximum pump back pressure (i.e., maximum pressure the pump can work against), maximum flow rate (flow rate when there is zero back pressure), and flow rate as a function of the height of the pump outlet. We further demonstrate combining 5 valves and one DC to create a 3-to-2 multiplexer with integrated pump. In addition to serial multiplexing, we also show that the device can operate as a mixer. Importantly, we illustrate the rapid fabrication and test cycles that 3D printing makes possible by implementing a new multiplexer design to improve mixing, and fabricate and test it within one day.

  2. Titanium in Engine Valve Systems

    Science.gov (United States)

    Allison, J. E.; Sherman, A. M.; Bapna, M. R.

    1987-03-01

    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a twoto-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance. When properly manufactured, titanium valves have been shown to withstand very stringent durability testing, indicating the technical feasibility of this approach to fuel economy improvement.

  3. Large Scale Magnetostrictive Valve Actuator

    Science.gov (United States)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  4. 49 CFR 179.400-19 - Valves and gages.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Valves and gages. 179.400-19 Section 179.400-19...-19 Valves and gages. (a) Valves. Manually operated shut-off valves and control valves must be... liquid flow rates. All valves must be made from approved materials compatible with the lading and...

  5. The nordic aortic valve intervention (NOTION) trial comparing transcatheter versus surgical valve implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Søndergaard, Lars; Ihlemann, Nikolaj;

    2013-01-01

    Degenerative aortic valve (AV) stenosis is the most prevalent heart valve disease in the western world. Surgical aortic valve replacement (SAVR) has until recently been the standard of treatment for patients with severe AV stenosis. Whether transcatheter aortic valve implantation (TAVI) can...

  6. Aortic valve replacement with the Nicks annulus enlargement procedure 12 years after mitral valve replacement.

    Science.gov (United States)

    Kazama, S; Kurata, A; Yamashita, Y

    1999-10-01

    An aortic valve replacement was successfully performed employing the Nicks annulus enlargement procedure in a case of aortic valve stenosis with small annulus 12 years after mitral valve replacement. Previous mitral valve replacement does not preclude feasibility of the Nicks procedure.

  7. Transapical transcatheter valve-in-valve replacement for deteriorated mitral valve bioprosthesis without radio-opaque indicators: the "invisible" mitral valve bioprosthesis.

    Science.gov (United States)

    Rossi, Marco Luciano; Barbaro, Cristina; Pagnotta, Paolo; Cappai, Antioco; Ornaghi, Diego; Belli, Guido; Presbitero, Patrizia

    2015-02-01

    In view of the high number of bioprosthetic valves implanted during the past 30 years, an increasing number of patients are coming to medical attention because of degenerated bioprostheses. Transcatheter aortic valve-in-valve implantation has been described as a less invasive alternative to re-operation to treat severe structural valve deterioration. As far as degenerated mitral valve bioprostheses are concerned, transcatheter transapical mitral valve-in-valve replacement (TMVR) has been less commonly performed, but may also become a viable alternative to re-do replacement surgery. We describe treatment of a degenerated bioprosthetic mitral valve, characterised by complete absence of any radio-opaque landmarks making the TMVR procedure very challenging.

  8. Percutaneous heart valves; past, present and future.

    Science.gov (United States)

    Rozeik, M M; Wheatley, D J; Gourlay, T

    2014-09-01

    Percutaneous heart valves provide a promising future for patients refused surgery on the grounds of significant technical challenges or high risk for complications. Since the first human intervention more than 10 years ago, over 50 different types of valves have been developed. The CoreValve and Edwards SAPIEN valves have both experienced clinical trials and the latter has gained FDA approval for implantation in patients considered inoperable. Current complications, such as major vascular bleeding and stroke, prevent these valves from being commonly deployed in patients considered operable in conventional surgery. This review focuses on the past and present achievements of these valves and highlights the design considerations required to progress development further. It is envisaged that, with continued improvement in valve design and with increased clinical and engineering experience, percutaneous heart valve replacement may one day be a viable option for lower-risk operable patients.

  9. Statins for aortic valve stenosis

    Directory of Open Access Journals (Sweden)

    Luciana Thiago

    Full Text Available ABSTRACT BACKGROUND: Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. OBJECTIVES: To evaluate the effectiveness and safety of statins in aortic valve stenosis. METHODS: Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions. Selection criteria: Randomized controlled clinical trials (RCTs comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity, freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life. Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. MAIN RESULTS: We included four RCTs with 2360 participants comparing statins (1185 participants with placebo (1175 participants. We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD -0.54, 95% confidence interval (CI -1.88 to 0.80; participants = 1935; studies = 2, valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2

  10. Propellant isolation shutoff valve program

    Science.gov (United States)

    Merritt, F. L.

    1973-01-01

    An analysis and design effort directed to advancing the state-of-the-art of space storable isolation valves for control of flow of the propellants liquid fluorine/hydrazine and Flox/monomethylhydrazine is discussed. Emphasis is on achieving zero liquid leakage and capability of withstanding missions up to 10 years in interplanetary space. Included is a study of all-metal poppet sealing theory, an evaluation of candidate seal configurations, a valve actuator trade-off study and design description of a pneumo-thermally actuated soft metal poppet seal valve. The concepts and analysis leading to the soft seal approach are documented. A theoretical evaluation of seal leakage versus seal loading, related finishes and yield strengths of various materials is provided. Application of a confined soft aluminum seal loaded to 2 to 3 times yield strength is recommended. Use of either an electro-mechanical or pneumatic actuator appears to be feasible for the application.

  11. 2D SIMPLIFIED SERVO VALVE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel pilot stage valve called simplified 2D valve, which utilizes both rotary and linear motions of a single spool, is presented.The rotary motion of the spool incorporating hydraulic resistance bridge, formed by a damper groove and a crescent overlap opening, is utilized as pilot to actuate linear motion of the spool.A criterion for stability is derived from the linear analysis of the valve.Special experiments are designed to acquire the mechanical stiffness, the pilot leakage and the step response.It is shown that the sectional size of the spiral groove affects the dynamic response and the stiffness contradictorily and is also very sensitive to the pilot leakage.Therefore, it is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless, it is possible to sustain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level.

  12. Transapical Mitral Valve-in-Valve Replacement in Patient With Previous Complex Sternal Reconstruction.

    Science.gov (United States)

    Hynes, Conor F; Fatemi, Omid; Sharma, Aditya C; Nagy, Christian D; Trachiotis, Gregory D

    2016-01-01

    We present a complex case of a transapical redo mitral valve-in-valve replacement. Repeat mitral valve replacement was indicated for severe symptomatic bioprosthetic stenosis. In addition to the patient's numerous comorbidities that included diabetes, hepatic cirrhosis, ischemic cardiomyopathy, and atrial flutter, he had undergone a previous open mitral valve replacement that was complicated by sternal dehiscence requiring extensive chest wall reconstruction. Transapical approach was performed through left minithoracotomy incision with balloon-expandable valve. Transapical valve-in-valve replacement of a stenotic mitral bioprosthesis is a viable solution in a patient with previous complex chest wall reconstruction and multiple comorbidities.

  13. Deformation of Congenital Bicuspid Aortic Valves in Systole

    Science.gov (United States)

    Szeto, Kai; Pastuszko, Peter; Nigam, Vishal; Lasheras, Juan

    2012-11-01

    Clinical studies have shown that patients with congenital bicuspid aortic valves (CBAVs) develop degenerative calcification of the leaflets at young ages compared to normal tricuspid aortic valves (TAVs). It has been hypothesized that the asymmetrical geometry of the leaflets in CBAVs and the associate changes in flow shear stresses and excessive strain rate levels are possible causes for the early calcification. Central to the validation of this hypothesis is the need to quantify the differences in strain rate levels between the BAVs and TAVs. We simulate the CBAVs by surgically stitching two of the leaflets of a porcine aortic valve together. To quantify strain differences, we performed in-vitro experiments in both BAVs and TAVs by tracking the 3-D motion of small dots marked on each leaflet surface. We then used phase-locked stereo photogrammetry to measure the strain rates in both radial and circumferential directions during the whole cardiac cycle. In the BAVs' case, the fused leaflet experiences an almost 30% increase in the radial stretching when fully open. RNA profiling of human aortic valve interstitial cells exposed to cyclic stretch shows that the increased stretch experienced by the BAVs results in increased levels of INTERLEUKINS (ILs) and other known inflammatory markers associated with aortic valve calcification. Together, these observations suggest that the abnormal stretch experienced by BAVs activates inflammation gene expression.

  14. Pregnancy-induced remodeling of heart valves.

    Science.gov (United States)

    Pierlot, Caitlin M; Moeller, Andrew D; Lee, J Michael; Wells, Sarah M

    2015-11-01

    Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves.

  15. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik;

    2011-01-01

    Mitral valve regurgitation (MR) is the secondmost frequent valve disease in Europe. Untreated MR causes considerable morbidity and mortality. In the elderly, as many as half of these patients are denied surgery because of an estimated high surgical risk. Percutaneous mitral valve repair with the ...... with the MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  16. Infective endocarditis following percutaneous pulmonary valve replacement

    DEFF Research Database (Denmark)

    Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj;

    2013-01-01

    Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult.......Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult....

  17. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik;

    2011-01-01

    Mitral valve regurgitation (MR) is the secondmost frequent valve disease in Europe. Untreated MR causes considerable morbidity and mortality. In the elderly, as many as half of these patients are denied surgery because of an estimated high surgical risk. Percutaneous mitral valve repair...... with the MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  18. Deficient signaling via Alk2 (Acvr1 leads to bicuspid aortic valve development.

    Directory of Open Access Journals (Sweden)

    Penny S Thomas

    Full Text Available Bicuspid aortic valve (BAV is the most common congenital cardiac anomaly in humans. Despite recent advances, the molecular basis of BAV development is poorly understood. Previously it has been shown that mutations in the Notch1 gene lead to BAV and valve calcification both in human and mice, and mice deficient in Gata5 or its downstream target Nos3 have been shown to display BAVs. Here we show that tissue-specific deletion of the gene encoding Activin Receptor Type I (Alk2 or Acvr1 in the cushion mesenchyme results in formation of aortic valve defects including BAV. These defects are largely due to a failure of normal development of the embryonic aortic valve leaflet precursor cushions in the outflow tract resulting in either a fused right- and non-coronary leaflet, or the presence of only a very small, rudimentary non-coronary leaflet. The surviving adult mutant mice display aortic stenosis with high frequency and occasional aortic valve insufficiency. The thickened aortic valve leaflets in such animals do not show changes in Bmp signaling activity, while Map kinase pathways are activated. Although dysfunction correlated with some pro-osteogenic differences in gene expression, neither calcification nor inflammation were detected in aortic valves of Alk2 mutants with stenosis. We conclude that signaling via Alk2 is required for appropriate aortic valve development in utero, and that defects in this process lead to indirect secondary complications later in life.

  19. Advantages with small control valves

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Gunnar

    2008-09-15

    Between 1995 and 2005, the Swedish District Heating Association carried out several research projects concerning small dimensions on control valves. This lecture aims at giving a summary of these findings which, if they are carried out, have a great impact on the district heating system. The outcome is advantages on both the production side and the customer side. Some of the project's conclusions are as follows: 1. The simulations show that the consequences of temperature disturbances can be reduced when applying smaller control valves, especially at low outdoor temperatures (-5 deg C). 2. The consequences of flow disturbances (pump stop) are not depending on the outdoor temperature (heat demand), but results over the whole year in reduced maximum flow during the process of operation recovery. With adequately reduced valve size, the resulting maximum flow at restart can be approximately reduced to the half, leading in reduced need of pumping peak power. 3. Similarly, the maximum peak power taken from the net at net recovery will be reduced, however, this effect is not as strong as that for flow. 4. Generally, we have found clear indications for that the adjustment of the K{sub vs}-values of control valves in substations should follow a certain logical order of priority. An important factor is the location of substations in respect to the production plant and to the pressure control points in the network. Another important factor is the absolute K{sub vs}-value of the over sizing, i.e. the difference of the actual installed valve and the targeted valve size. 5. Smaller size of control valves means also an improvement of the everyday operation of the district heating net, especially in the case when flow and power peaks are expected to occur. Examples for that could be the morning peaks with increase heat and hot water demands, or such events when the air temperature is decreasing very fast because of weather phenomena. Smaller control valves will smear out the

  20. Fast-acting valve actuator

    Science.gov (United States)

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  1. Surface spin-valve effect.

    Science.gov (United States)

    Yanson, I K; Naidyuk, Yu G; Fisun, V V; Konovalenko, A; Balkashin, O P; Triputen, L Yu; Korenivski, V

    2007-04-01

    We report an observation of spin-valve-like hysteresis within a few atomic layers at a ferromagnetic interface. We use phonon spectroscopy of nanometer-sized point contacts as an in situ probe to study the mechanism of the effect. Distinctive energy phonon peaks for contacts with dissimilar nonmagnetic outer electrodes allow localizing the observed spin switching to the top or bottom interfaces for nanometer thin ferromagnetic layers. The mechanism consistent with our data is energetically distinct atomically thin surface spin layers that can form current- or field-driven surface spin-valves within a single ferromagnetic film.

  2. Whitey SCHE Gauge and Root Valves

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-11

    These valves are 1/2 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the SCHa System between the helium bottle supply manifolds and safety class helium pressure instrumentation, and in lower pressure SCHa supply line.

  3. Pregnancy in women with prosthetic heart valves

    NARCIS (Netherlands)

    Pieper, P. G.; Balci, A.; Van Dijk, A. P.

    2008-01-01

    Pregnancy in women with mechanical valve prostheses has a high maternal complication rate including valve thrombosis mid death. Coumarin derivatives are relatively safe for the mother with a lower incidence of valve thrombosis than unfractionated and low-molecular-weight heparin, but carry the risk

  4. Porcine Tricuspid Valve Anatomy and Human Compatibility

    DEFF Research Database (Denmark)

    Waziri, Farhad; Lyager Nielsen, Sten; Hasenkam, J. Michael

    2016-01-01

    before clinical use. The study aim was to evaluate and compare the tricuspid valve anatomy of porcine and human hearts. METHODS: The anatomy of the tricuspid valve and the surrounding structures that affect the valve during a cardiac cycle were examined in detail in 100 fresh and 19 formalin...

  5. Whitey SCHE Gauge and Root Valves

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-03

    These valves are 1/2 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the SCHe System between the helium bottle supply manifolds and safety class helium pressure instrumentation, and in lower pressure SCHe supply line.

  6. Aerodynamic Characteristics of Tracheostomy Speaking Valves.

    Science.gov (United States)

    Fornataro-Clerici, Lisa; Zajac, David J.

    1993-01-01

    Pressure-flow characteristics were determined for four different one-way valves (Kisner, Montgomery, Olympic, and Passy-Muir) used for speech production in tracheotomy patients. Results indicated significant differences in resistance among the valves, with the resistance of one valve substantially greater than that of the normal upper airways.…

  7. 14 CFR 27.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 27.995 Section 27.995... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must be a positive, quick-acting valve to shut off fuel to each engine individually. (b) The control...

  8. 14 CFR 29.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 29.995 Section 29.995... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition to meeting the requirements of § 29.1189, each fuel valve must— (a) (b) Be supported so that no...

  9. 14 CFR 25.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 25.995 Section 25.995... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition to the requirements of § 25.1189 for shutoff means, each fuel valve must— (a) (b) Be supported...

  10. 14 CFR 29.1025 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff.... (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  11. 14 CFR 25.1025 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff... feathering. (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  12. 49 CFR 195.258 - Valves: General.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: General. 195.258 Section 195.258... PIPELINE Construction § 195.258 Valves: General. (a) Each valve must be installed in a location that is accessible to authorized employees and that is protected from damage or tampering. (b) Each submerged...

  13. 14 CFR 121.239 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 121.239 Section 121.239..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.239 Oil valves. (a) Each oil valve must— (1) Comply with § 121.257; (2) Have positive stops or suitable index provisions in the...

  14. 14 CFR 121.235 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 121.235 Section 121.235..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.235 Fuel valves. Each fuel valve must— (a) Comply with § 121.257; (b) Have positive stops or suitable index provisions in the...

  15. 49 CFR 229.109 - Safety valves.

    Science.gov (United States)

    2010-10-01

    ....109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a combined capacity to prevent an accumulation of pressure of more than five pounds per square inch above the... ends of the safety valve discharge lines shall be located or protected so that discharged steam...

  16. Aerodynamic Characteristics of Tracheostomy Speaking Valves.

    Science.gov (United States)

    Fornataro-Clerici, Lisa; Zajac, David J.

    1993-01-01

    Pressure-flow characteristics were determined for four different one-way valves (Kisner, Montgomery, Olympic, and Passy-Muir) used for speech production in tracheotomy patients. Results indicated significant differences in resistance among the valves, with the resistance of one valve substantially greater than that of the normal upper airways.…

  17. Flow and plate motion in compressor valves

    NARCIS (Netherlands)

    Habing, Reinder André

    2005-01-01

    The Basic Valve Theory is based on steady ow characteristics. Therefore unsteady ow conditions in the model valve have been considered in order to assess effects of unsteadiness on the performance of the Basic Valve Theory. The instantaneous gas force was predicted rather accurately by the theory. H

  18. Staphylococcus saprophyticus causing native valve endocarditis.

    Science.gov (United States)

    Garduño, Eugenio; Márquez, Irene; Beteta, Alicia; Said, Ibrahim; Blanco, Javier; Pineda, Tomás

    2005-01-01

    Coagulase negative staphylococci are a rare cause of native valve endocarditis. Staphylococcus saprophyticus is a coagulase-negative Staphylococcus infrequently reported as a human pathogen, and most of the cases reported are urinary tract infections. We describe a case of native valve endocarditis attributed to this organism. The patient needed valve replacement due to heart failure.

  19. Miniature piezo electric vacuum inlet valve

    Science.gov (United States)

    Keville, Robert F.; Dietrich, Daniel D.

    1998-03-24

    A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

  20. Fluid–Structure Interaction Analysis of Papillary Muscle Forces Using a Comprehensive Mitral Valve Model with 3D Chordal Structure

    Energy Technology Data Exchange (ETDEWEB)

    Toma, Milan; Jensen, Morten Ø.; Einstein, Daniel R.; Yoganathan, Ajit P.; Cochran, Richard P.; Kunzelman, Karyn S.

    2015-07-17

    Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in-vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with *CT. Experimental data from the in-vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed lea et dynamics, and force vectors from the in-vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements are important in validating and adjusting material parameters in computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.

  1. Acoustic valve leak detection: Initial program development, implementation & experience

    Energy Technology Data Exchange (ETDEWEB)

    Wicker, G.L. [Baltimore Gas and Electric Company, Baltimore, MD (United States)

    1996-07-01

    Acoustic valve leak detection is one of the many test techniques employed in modern power plants with active predictive maintenance programs. In 1994, a valve leak detection program was implemented within Baltimore Gas and Electric`s Fossil Energy Division. Within two years, the program resulted in energy savings in excess of one million dollars. The leak detection program has become an essential technology that has reduced plant heat rate losses, prevented unnecessary valve maintenance and increased plant awareness of potential losses. This paper describes program development, implementation and test methodology of Baltimore Gas and Electric`s acoustic leak detection program. Key topics include equipment description, program measurements, methodology and leak identification methods. The paper also will include discussion on the practical approach of equipment selection and program philosophies.

  2. The presence of fructosamine in human aortic valves is associated with valve stiffness.

    Science.gov (United States)

    Kishabongo, Antoine S; Katchunga, Philippe; Cikomola, Justin C; De Somer, Filip M; De Buyzere, Marc L; Speeckaert, Marijn M; Delanghe, Joris R

    2016-09-01

    Human heart valves are prone to glycation, a fundamental process of ageing. The aim of this study was to establish the relationship between fructosamine formation and the mechanical properties of human aortic valves. 67 patients (age: 76±8 years) diagnosed with an aortic valve stenosis, who underwent an aortic valve replacement were enrolled. Fructosamine and calcium concentrations in aortic valves were determined. Using a transthoracic Doppler echocardiography, aortic valve orifice area and transvalvular pressure gradients were measured. In a subgroup of 32 patients, the aortic valve orifice area was sufficient to carry out mechanical testing on a LFPlus Universal material tester. An in vitro removal of fructosamine of the valve was initiated using ATP-dependent fructosamine 3-kinase (FN3K). A significant correlation was found between the aortic valve fructosamine concentration and the calculated aortic valve orifice area: Y (aortic valve orifice area, mm(2))=1.050-0.228X (aortic valve fructosamine concentration, µmol/g valve) (r=-0.38). A significantly higher calcium concentration was measured in the aortic valves of diabetics in comparison with those of non-diabetics. A multiple regression analysis revealed that the presence of diabetes mellitus and aortic valve fructosamine concentration were the main predictors of the extensibility of the aortic valves. In the in vitro deglycation study, a significant lower aortic valve fructosamine concentration was detected after treatment with FN3K. This resulted in an increased flexibility of the aortic valves. Although no direct causativeness is proven with the presented results, which just show an association between fructosamine, the effect of FN3K and aortic valve stiffness, the present study points for the first time towards a possible additional role of the Amadori products in the biomechanical properties of ageing aortic valves. Published by the BMJ Publishing Group Limited. For permission to use (where not

  3. Pressure relief valve/safety relief valve testing

    Energy Technology Data Exchange (ETDEWEB)

    Murray, W.A.; Hamm, E.R.; Barber, J.R.

    1994-02-01

    Pressure vessels and piping systems are protected form overpressurization by pressure relief valves. These safety features are required to be tested-inspected on some periodic basis and, in most cases witnessed by a third party inspector. As a result nonconformances found by third parties Westinghouse Hanford Company initiated a task team to develop a pressure safety program. This paper reveals their findings.

  4. Aortic valve stenosis after previous coronary bypass: Transcatheter valve implantation or aortic valve replacement?

    Directory of Open Access Journals (Sweden)

    Jegaden Olivier

    2012-05-01

    Full Text Available Abstract We report a prospective comparison between transcatheter valve implantation (TAVI, n = 13 and surgical aortic valve replacement (AVR, n = 10 in patients with severe aortic valve stenosis and previous coronary bypass surgery (CABG. All patients had at least bilateral patent internal thoracic arteries bypass without indication of repeat revascularization. After a similar post-procedure outcome, despite one early death in TAVI group, the 1-year survival was 100% in surgical group and in transfemoral TAVI group, and 73% in transapical TAVI group. When previous CABG is the lone surgical risk factor, indications for a TAVI procedure have to be cautious, specially if transfemoral approach is not possible.

  5. Addressing Ozone Layer Depletion

    Science.gov (United States)

    Access information on EPA's efforts to address ozone layer depletion through regulations, collaborations with stakeholders, international treaties, partnerships with the private sector, and enforcement actions under Title VI of the Clean Air Act.

  6. Addressivity in cogenerative dialogues

    Science.gov (United States)

    Hsu, Pei-Ling

    2014-03-01

    Ashraf Shady's paper provides a first-hand reflection on how a foreign teacher used cogens as culturally adaptive pedagogy to address cultural misalignments with students. In this paper, Shady drew on several cogen sessions to showcase his journey of using different forms of cogens with his students. To improve the quality of cogens, one strategy he used was to adjust the number of participants in cogens. As a result, some cogens worked and others did not. During the course of reading his paper, I was impressed by his creative and flexible use of cogens and at the same time was intrigued by the question of why some cogens work and not others. In searching for an answer, I found that Mikhail Bakhtin's dialogism, especially the concept of addressivity, provides a comprehensive framework to address this question. In this commentary, I reanalyze the cogen episodes described in Shady's paper in the light of dialogism. My analysis suggests that addressivity plays an important role in mediating the success of cogens. Cogens with high addressivity function as internally persuasive discourse that allows diverse consciousnesses to coexist and so likely affords productive dialogues. The implications of addressivity in teaching and learning are further discussed.

  7. In-plane cost-effective magnetically actuated valve for microfluidic applications

    Science.gov (United States)

    Pugliese, Marco; Ferrara, Francesco; Bramanti, Alessandro Paolo; Gigli, Giuseppe; Maiorano, Vincenzo

    2017-04-01

    We present a new in-plane magnetically actuated microfluidic valve. Its simple design includes a circular area joining two channels lying on the same plane. The area is parted by a septum lying on and adhering to a magneto-active polymeric ‘floor’ membrane, keeping the channels normally separated (valve closed). Under the action of a magnetic field, the membrane collapses, letting the liquid flow below the septum (valve open). The valve was extensively characterized experimentally, and modeled and optimized theoretically. The growing interest in lab on chips, especially for diagnostics and precision medicine, is driving researchers towards smart, efficient and low cost solutions to the management of biological samples. In this context, the valve developed in this work represents a useful building-block for microfluidic applications requiring precise flow control, its main features being easy and rapid manufacturing, biocompatibility and low cost.

  8. Enhanced rhamnolipids production via efficient foam-control using stop valve as a foam breaker.

    Science.gov (United States)

    Long, Xuwei; Shen, Chong; He, Ni; Zhang, Guoliang; Meng, Qin

    2017-01-01

    In this study, a stop valve was used as a foam breaker for dealing with the massive overflowing foam in rhamnolipid fermentation. As found, a stop valve at its tiny opening could break over 90% of the extremely stable rhamnolipid foam into enriched liquid when foam flows through the sharp gap in valve. The efficient foam-control by the stop valve considerably improved the rhamnolipid fermentation and significantly enhanced the rhamnolipid productivity by 83% compared to the regular fermentation. This efficient foam breaking was mainly achieved by a high shear rate in combination with fast separation of air from the collapsed foam. Altogether, the stop valve possessed a great activity in breaking rhamnolipid foam, and the involving mechanism holds the potential for developing efficient foam breakers for industrial rhamnolipid fermentation.

  9. Field Experience with Lock Culvert Valves

    Science.gov (United States)

    2013-12-01

    interesting accounts regarding their lock culvert valves. ST. LAWRENCE SEAWAY Eisenhower and Snell Locks. The valves on the Eisenhower and Snell Locks...Tainter Valve Design Lift, ft Eisenhower St. Lawrence Seaway 80 x 860 12 x 14 21.0 DSP 43 Snell St. Lawrence Seaway 80 x 860 12 x 14 21.0 3 DSP, 1 VF 49...vertical-frame valves were furnished to the SLSDC in January 2011, and one was installed in the south filling-valve location at Snell Lock. An option

  10. Aortic valve surgery - minimally invasive

    Science.gov (United States)

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... A.M. Editorial team. Related MedlinePlus Health Topics Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  11. Microprocessor-Based Valved Controller

    Science.gov (United States)

    Norman, Arnold M., Jr.

    1987-01-01

    New controller simpler, more precise, and lighter than predecessors. Mass-flow controller compensates for changing supply pressure and temperature such as occurs when gas-supply tank becomes depleted. By periodically updating calculation of mass-flow rate, controller determines correct new position for valve and keeps mass-flow rate nearly constant.

  12. Rotary actuators for plastic valves

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, M. [Georg Fischer Piping Systems Ltd, Schaffhausen (Switzerland)

    2004-07-01

    Flexibility and modularity plus a high level of quality are the defining characteristics of this new generation of actuators from Georg Fischer. In conjunction with the new 546 ball valve, the PA 11/PA 21 pneumatic actuators and the EA 11/EA 21 electric actuators form an optimally co-ordinated system. (orig.)

  13. The future of transcatheter mitral valve interventions: competitive or complementary role of repair vs. replacement?

    Science.gov (United States)

    Maisano, Francesco; Alfieri, Ottavio; Banai, Shmuel; Buchbinder, Maurice; Colombo, Antonio; Falk, Volkmar; Feldman, Ted; Franzen, Olaf; Herrmann, Howard; Kar, Saibal; Kuck, Karl-Heinz; Lutter, Georg; Mack, Michael; Nickenig, Georg; Piazza, Nicolo; Reisman, Mark; Ruiz, Carlos E; Schofer, Joachim; Søndergaard, Lars; Stone, Gregg W; Taramasso, Maurizio; Thomas, Martyn; Vahanian, Alec; Webb, John; Windecker, Stephan; Leon, Martin B

    2015-07-07

    Transcatheter mitral interventions has been developed to address an unmet clinical need and may be an alternative therapeutic option to surgery with the intent to provide symptomatic and prognostic benefit. Beyond MitraClip therapy, alternative repair technologies are being developed to expand the transcatheter intervention armamentarium. Recently, the feasibility of transcatheter mitral valve implantation in native non-calcified valves has been reported in very high-risk patients. Acknowledging the lack of scientific evidence to date, it is difficult to predict what the ultimate future role of transcatheter mitral valve interventions will be. The purpose of the present report is to review the current state-of-the-art of mitral valve intervention, and to identify the potential future scenarios, which might benefit most from the transcatheter repair and replacement devices under development.

  14. Mitral Valve Repair: The Chordae Tendineae

    Directory of Open Access Journals (Sweden)

    Carlos-A Mestres

    2015-10-01

    Full Text Available Repair of the mitral valve is the treatment of choice for mitral valve regurgitation when the anatomy is favorable. It is well known that mitral valve repair enjoys better clinical and functional results than any other type of valve substitute. This fact is beyond doubt regardless of the etiology of the valve lesion and is of particular importance in degenerative diseases.This review analyzes the most important advances in the knowledge of the anatomy, pathophysiology, and chordal function of the mitral valve as well as the different alternatives in the surgical repair and clinical results of the most prevalent diseases of the mitral valve. An attempt has been made to organize the acquired information available in a practical way.

  15. Transvalvular mitral regurgitation following mitral valve replacement a diagnostic dilemma

    OpenAIRE

    U S Dinesh Kumar; Umesh Nareppa; Shyam Prasad Shetty; Murugesh Wali

    2015-01-01

    After mitral valve replacement with a prosthetic valve, the valve should be competent and there should not be any residual prosthetic valve regurgitation. Transvalvular residual prosthetic valve regurgitation are difficult to diagnose and quantify. we are reporting interesting TEE images as a diagnostic dilemma in a case of transvalvular mitral regurgitation following mitral valve replacement secondary to entrapment of sub-valvular apparatus in a Chitra mechanical heart valve.

  16. Transcatheter aortic valve prosthesis surgically replaced 4 months after implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Lund, Jens Teglgaard; Engstrøm, Thomas;

    2010-01-01

    Transcatheter aortic valve implantation is a new and rapidly evolving treatment option for high-risk surgical patients with degenerative aortic valve stenosis. Long-term results with these new valve prostheses are lacking, and potential valve dysfunction and failure would require valve replacement....... We report the first case of surgical valve replacement in a patient with a dysfunctional transcatheter-implanted aortic valve prosthesis 4 months after implantation....

  17. Sucrose Diffusion in Decellularized Heart Valves for Freeze-Drying.

    Science.gov (United States)

    Wang, Shangping; Oldenhof, Harriëtte; Goecke, Tobias; Ramm, Robert; Harder, Michael; Haverich, Axel; Hilfiker, Andres; Wolkers, Willem Frederik

    2015-09-01

    Decellularized heart valves can be used as starter matrix implants for heart valve replacement therapies in terms of guided tissue regeneration. Decellularized matrices ideally need to be long-term storable to assure off-the-shelf availability. Freeze-drying is an attractive preservation method, allowing storage at room temperature in a dried state. However, the two inherent processing steps, freezing and drying, can cause severe damage to extracellular matrix (ECM) proteins and the overall tissue histoarchitecture and thus impair biomechanical characteristics of resulting matrices. Freeze-drying therefore requires a lyoprotective agent that stabilizes endogenous structural proteins during both substeps and that forms a protective glassy state at room temperature. To estimate incubation times needed to infiltrate decellularized heart valves with the lyoprotectant sucrose, temperature-dependent diffusion studies were done using Fourier transform infrared spectroscopy. Glycerol, a cryoprotective agent, was studied for comparison. Diffusion of both protectants was found to exhibit Arrhenius behavior. The activation energies of sucrose and glycerol diffusion were found to be 15.9 and 37.7 kJ·mol(-1), respectively. It was estimated that 4 h of incubation at 37°C is sufficient to infiltrate heart valves with sucrose before freeze-drying. Application of a 5% sucrose solution was shown to stabilize acellular valve scaffolds during freeze-drying. Such freeze-dried tissues, however, displayed pores, which were attributed to ice crystal damage, whereas vacuum-dried scaffolds in comparison revealed no pores after drying and rehydration. Exposure to a hygroscopic sucrose solution (80%) before freeze-drying was shown to be an effective method to diminish pore formation in freeze-dried ECMs: matrix structures closely resembled those of control samples that were not freeze-dried. Heart valve matrices were shown to be in a glassy state after drying, suggesting that they can

  18. Fault diagnosis of reciprocating compressor valve with the method integrating acoustic emission signal and simulated valve motion

    Science.gov (United States)

    Wang, Yuefei; Xue, Chuang; Jia, Xiaohan; Peng, Xueyuan

    2015-05-01

    This paper proposes a method of diagnosing faults in reciprocating compressor valves using the acoustic emission signal coupled with the simulated valve motion. The actual working condition of a valve can be obtained by analyzing the acoustic emission signal in the crank angle domain and the valve movement can be predicted by simulating the valve motion. The exact opening and closing locations of a normal valve, provided by the simulated valve motion, can be used as references for the valve fault diagnosis. The typical valve faults are diagnosed to validate the feasibility and accuracy of the proposed method. The experimental results indicate that this method can easily distinguish the normal valve, valve flutter and valve delayed closing conditions. The characteristic locations of the opening and closing of the suction and discharge valves can be clearly identified in the waveform of the acoustic emission signal and the simulated valve motion.

  19. Early Clinical Outcome of Mitral Valve Replacement Using a Newly Designed Stentless Mitral Valve for Failure of Initial Mitral Valve Repair.

    Science.gov (United States)

    Nishida, Hidefumi; Kasegawa, Hitoshi; Kin, Hajime; Takanashi, Shuichiro

    2016-12-21

    Here we report the early outcome of mitral valve replacement using a newly designed stentless mitral valve for failure of initial mitral valve repair. Mitral valve plasty (MVP) for mitral regurgitation is currently a standard technique performed worldwide. However, whether mitral valve repair should be performed for patients with advanced leaflet damage or complicated pathology remains controversial. Mitral valve replacement might be feasible for patients who have undergone failed initial MVP; however, it is not an optimal treatment because of poor valve durability and the need for anticoagulative therapy. We report two cases of successful mitral valve replacement using a newly designed stentless mitral valve made of fresh autologous pericardium, which may have a potential benefit over mitral valve repair or mitral valve replacement with a mechanical or bioprosthetic valve.

  20. Myocardial hypertrophy after pulmonary regurgitation and valve implantation in pigs

    DEFF Research Database (Denmark)

    Smith, Julie; Goetze, Jens Peter; Søndergaard, Lars;

    2012-01-01

    BACKGROUND: Patients may suffer from right ventricular (RV) failure and malignant cardiac arrhythmias after late pulmonary valve replacement correcting pulmonary regurgitation (PR). But the underlying mechanisms of the refractory arrhythmias are not well understood. METHODS: The aim of present...... study was to characterize the RV myocardium after percutaneous pulmonary valve implantation (PPVI) in a porcine model after severe PR for 3months. RV histology was evaluated with morphometric methods and RV function was assessed with electrophysiology, echocardiography, and biochemical measures...... and plasma natriuretic peptides were unchanged. CONCLUSIONS: The RV does not completely recover after three months of PR with persistent myocardial hypertrophy one month after PPVI. Future studies should address whether RV chamber and cellular hypertrophy, without fibrosis or interventional scar tissue, may...

  1. Hardfacing materials used in valves for seating and wear surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, W.G.

    1996-12-01

    Most valves and essentially all critical service valves utilize hardfacing materials for seating and wear surfaces to minimize wear and galling. The type of hardfacing materials used, the methods of deposition, and the quality of the final product all contribute to the wear characteristics, required operating force, and life of the final product. Over the last forty years the most prevalent hardfacing materials furnished to the commercial nuclear industry consisted of cobalt base and nickel base materials. In the last several years there has been extensive development and evaluation work performed on iron base hardfacing materials. This presentation will address the wear characteristics of the various materials and the importance of consistent quality of deposited materials necessary to achieve optimum product performance and longevity.

  2. A Kinematic Analysis of the Variable Valve Timing Mechanism with Three Elements and Continuous Valve Lift

    Directory of Open Access Journals (Sweden)

    Stelian Mihalcea

    2010-01-01

    Full Text Available An innovating solution for throttle-free load control for spark-ignition engines is Variable Valve Timing system (VVT System, or VVA - Variable Valve Actuation System. In this paper is presented an analytic method for kinematic analysis of the valve timing mechanism with three elements, which mainly includes the camshaft, the roller rocker finger and an intermediate rocker arm. This type of mechanism ensures a continuous valve lift (VVL System between two extreme valve heights. It is also presented the numerical example for the variable valve lift mechanism’s motion.

  3. Redoing a bioprosthetic tricuspid valve replacement with pacemaker wire through the ruined bioprosthetic valve orifice

    Institute of Scientific and Technical Information of China (English)

    GUO Hong-wei; PAN Shi-wei; SONG Yun-hu; HU Sheng-shou

    2011-01-01

    Severe tricuspid regurgitation with permanent pacemaker wire passing through the orifice of bioprosthetic tricuspid valve is extremely rare. We present a case of such kind of patient and redid bioprosthetic tricuspid valve replacement. A hawk mouth forceps for bone surgery was used to cut off the mental ring of ruined bioprosthetic tricuspid valve and the ruined valve was removed. A new bioprosthetic tricuspid valve was implanted and the wire of permanent pacemaker was left outside the ring of bioprosthetic tricuspid valve. This method may be helpful for such kind of patient.

  4. Valve-regulated lead-acid batteries

    Science.gov (United States)

    Berndt, D.

    Valve-regulated lead-acid (VRLA) batteries with gelled electrolyte appeared as a niche market during the 1950s. During the 1970s, when glass-fiber felts became available as a further method to immobilize the electrolyte, the market for VRLA batteries expanded rapidly. The immobilized electrolyte offers a number of obvious advantages including the internal oxygen cycle which accommodates the overcharging current without chemical change within the cell. It also suppresses acid stratification and thus opens new fields of application. VRLA batteries, however, cannot be made completely sealed, but require a valve for gas escape, since hydrogen evolution and grid corrosion are unavoidable secondary reactions. These reactions result in water loss, and also must be balanced in order to ensure proper charging of both electrodes. Both secondary reactions have significant activation energies, and can reduce the service life of VRLA batteries, operated at elevated temperature. This effect can be aggravated by the comparatively high heat generation caused by the internal oxygen cycle during overcharging. Temperature control of VRLA batteries, therefore, is important in many applications.

  5. Hydrodynamic Performance of the Medtronic CoreValve and the Edwards SAPIEN XT Transcatheter Heart Valve in Surgical Bioprostheses: An In Vitro Valve-in-Valve Model.

    Science.gov (United States)

    Sedaghat, Alexander; Sinning, Jan-Malte; Utzenrath, Marc; Ghalati, Pejman Farhadi; Schmitz, Christoph; Werner, Nikos; Nickenig, Georg; Grube, Eberhard; Ensminger, Stephan; Steinseifer, Ulrich; Kuetting, Maximilian

    2016-01-01

    Valve-in-valve transcatheter aortic valve replacement (TAVR) is becoming a valuable option with promising clinical results in failed bioprosthetic heart valves. Sizing recommendations are based on size compatibility rather than on broad clinical data, in vitro measurements, or biomechanical evidence. The hemodynamic performance of transcatheter heart valves within degenerated surgical heart valves is unknown. We evaluated the in vitro hydrodynamic performance of two commercially available transcatheter heart valves (Medtronic CoreValve [Medtronic, Minneapolis, MN] and Edwards SAPIEN XT [Edwards Lifesciences, Irvine, CA]) in two different bioprosthetic aortic valves (Edwards Perimount [Edwards Lifesciences] and St. Jude Trifecta [St. Jude Medical, St. Paul, MN]). Within the Edwards Perimount (23 mm) prosthesis, pressure gradients were higher for the SAPIEN XT compared with the CoreValve (11.2 ± 0.1 mm Hg versus 10.1 ± 0.1 mm Hg, p < 0.01), whereas effective orifice area (1.99 ± 0.01 cm(2) versus 1.80 ± 0.01 cm(2), p < 0.01) and total paravalvular leakage (9.0% ± 1.0% versus 5.4% ± 1.3%, p < 0.01) were increased when using the CoreValve. Similarly, measurements in the St. Jude Trifecta revealed higher transvalvular pressure gradients (13.0 ± 0.2 mm Hg versus 10.9 ± 0.3 mm Hg, p < 0.01) and lower effective orifice area for the SAPIEN XT compared with the CoreValve. However, total relative regurgitation was higher with SAPIEN XT as compared with the CoreValve in St. Jude Trifecta prostheses (11.2% ± 1.4% versus 8.3% ± 0.9%, p < 0.01). Both transcatheter heart valve prostheses performed well in the described valve-in-valve settings. Hydrodynamic results were in line with the International Organization for Standardization standards for all configurations. The observed differences indicate a necessity for preclinical valve-in-valve tests in addition to clinical long-term data about longevity. Copyright © 2016 The Society of Thoracic Surgeons. Published by

  6. A novel technique in a sheep model for evaluating prosthetic heart valve performance.

    Science.gov (United States)

    Puc, M M; Marra, S W; Tran, H S; Cilley, J H; Hewitt, C W; DelRossi, A J

    2001-01-01

    There have been many various animal studies to evaluate the structural integrity and antithrombogenicity of prosthetic heart valves. We were interested in developing a novel sheep model to study the thrombogenicity of mechanical heart valves placed into the systemic circulation but without the need for cardiac bypass. Also, we wanted to minimize the risk ofparaplegia from complete thoracic aortic clamping. Six sheep underwent left lateral thoracotomy for placement of a mechanical heart valve in parallel with the descending thoracic aorta. A valved conduit with a dacron tube graft sutured to the back end was fashioned. Employing partial aortic occlusion with a side-biting clamp, the proximal and distal ends were anastomosed in an end-to-side fashion. Once flow was confirmed through the graft, the native aorta was occulded with umbilical tape. The sheep received no postoperative anticoagulation. The median operative time and estimated blood loss (EBL) was 170 min and 250 cc, respectively. Patency of the valved conduits was confirmed during the initial procedure, and there was no incidence of paraplegia postoperatively. Two animals expired shortly after extubation and at necropsy the valved conduits were patent with preserved valve function. The four survivors were sacrificed a median of 37 days postoperatively. Prior to euthanasia, the valved conduits were evaluated in situ with ultrasound. In all cases, the valves had clot formation at the hinges, which prevented active movement of the leaflets. This novel in vivo technique provides an alternative in testing the thrombogenicity of prosthetic heart valves without cardiac bypass or the risk of paraplegia in an animal that is extremely sensitive to complete aortic cross-clamp.

  7. Traumatic Mitral Valve and Pericardial Injury

    Directory of Open Access Journals (Sweden)

    Nissar Shaikh

    2013-01-01

    Full Text Available Cardiac injury after blunt trauma is common but underreported. Common cardiac trauma after the blunt chest injury (BCI is cardiac contusion; it is very rare to have cardiac valve injury. The mitral valve injury during chest trauma occurs when extreme pressure is applied at early systole during the isovolumic contraction between the closure of the mitral valve and the opening of the aortic valve. Traumatic mitral valve injury can involve valve leaflet, chordae tendineae, or papillary muscles. For the diagnosis of mitral valve injury, a high index of suspicion is required, as in polytrauma patients, other obvious severe injuries will divert the attention of the treating physician. Clinical picture of patients with mitral valve injury may vary from none to cardiogenic shock. The echocardiogram is the main diagnostic modality of mitral valve injuries. Patient’s clinical condition will dictate the timing and type of surgery or medical therapy. We report a case of mitral valve and pericardial injury in a polytrauma patient, successfully treated in our intensive care unit.

  8. Flow Characteristics of Butterfly Valve by PIV and CFD

    Science.gov (United States)

    Kim, S. W.; Kim, J. H.; Choi, Y. D.; Lee, Y. H.

    Butterfly valves are widely used as on-off and control valves for industrial process. The importance of butterfly valves as control valves has been increasing because the pressure loss is smaller than other types of valves and compactness is very desirable for installation. These features are desirable for saving energy and high efficiency of instruments.

  9. 49 CFR 179.500-11 - Loading and unloading valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Loading and unloading valves. 179.500-11 Section...-113 and 107A) § 179.500-11 Loading and unloading valves. (a) Loading and unloading valve or valves shall be mounted on the cover or threaded into the marked end of tank. These valves shall be of...

  10. Segmented ball valve is easy to open and close

    Science.gov (United States)

    Prono, E.; Shinault, L. H.; Speisman, C.

    1966-01-01

    Segmented ball valve and flowmeter in the same spherical housing provide a valve that will handle large fluid volume without bulkiness and weight of blade valves or conventional ball valves. The valve is easily opened or closed and the flowmeter remains stationary, so errors are eliminated.

  11. Transesophageal echocardiography evaluation of tricuspid and pulmonic valves

    Directory of Open Access Journals (Sweden)

    Aneeta Bhatia

    2016-01-01

    Full Text Available The tricuspid is the lost valve and the pulmonary being the most anterior, is not visualized well on TEE; The Pulmonary valve is a semilunar valve that separates the right ventricle from the pulmonary artery. It is situated anterior and superior to the aortic valve, almost at right angle to the aortic valve and parallel to the beam of the ultrasound.

  12. Aerococcus viridans Native Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Wenwan Zhou

    2013-01-01

    Full Text Available Aerococcus viridans is an infrequent human pathogen and few cases of infective endocarditis have been reported. A case involving a 69-year-old man with colon cancer and hemicolectomy 14 years previously, without recurrence, is reported. A diagnosis of native mitral valve endocarditis was established on the basis of clinical presentation, characteristic echocardiographic findings and pathological specimen examination after urgent valve replacement. A viridans endocarditis appears to be particularly virulent, requiring a surgical approach in four of 10 cases reported and death in one of nine. Given the aggressive nature of A viridans endocarditis and the variable time to diagnosis (a few days to seven months, prompt recognition of symptoms and echocardiography, in addition to blood cultures, should be performed when symptoms persist.

  13. [MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT].

    Science.gov (United States)

    Tabata, Minoru

    2016-03-01

    Minimally invasive aortic valve replacement (MIAVR) is defined as aortic valve replacement avoiding full sternotomy. Common approaches include a partial sternotomy right thoracotomy, and a parasternal approach. MIAVR has been shown to have advantages over conventional AVR such as shorter length of stay and smaller amount of blood transfusion and better cosmesis. However, it is also known to have disadvantages such as longer cardiopulmonary bypass and aortic cross-clamp times and potential complications related to peripheral cannulation. Appropriate patient selection is very important. Since the procedure is more complex than conventional AVR, more intensive teamwork in the operating room is essential. Additionally, a team approach during postoperative management is critical to maximize the benefits of MIAVR.

  14. A correlation between long-term in vitro dynamic calcification and abnormal flow patterns past bioprosthetic heart valves.

    Science.gov (United States)

    Barannyk, Oleksandr; Fraser, Robert; Oshkai, Peter

    2017-06-01

    In this paper, a long-term in vitro dynamic calcification of three porcine aortic heart valves was investigated using a combined approach that involved accelerated wear testing of the valves in the rapid calcification solution, hydrodynamic assessment of the progressive change of effective orifice area (EOA) along with the transaortic pressure gradient, and quantitative visualization of the flow. The motivation for this study was developing a standardized, economical, and feasible in vitro testing methodology for bioprosthetic heart valve calcification, which would address both the hydrodynamic performance of the valves as well as the subsequent changes in the flow field. The results revealed the failure of the test valves at 40 million cycles mark, associated with the critical decrease in the EOA, followed by the increase in the maximum value of viscous shear stress of up to 52%, compared to the values measured at the beginning of the study. The decrease in the EOA was subsequently followed by the rapid increase in the maximum streamwise velocity of the central orifice jet up to the value of about 2.8 m/s, compared to the initial value of 2 m/s, and to the value of 2.2 m/s in the case of a control valve along with progressive narrowing of the velocity profile for two test valves. The significance of the current work is in demonstrating a correlation between calcification of the aortic valve and spatial as well as the temporal development of abnormal flow features.

  15. Extracellular matrix biomarker, fibulin-1, is closely related to NT-proBNP and soluble urokinase plasminogen activator receptor in patients with aortic valve stenosis (the SEAS study)

    DEFF Research Database (Denmark)

    Kruger, Ruan; Rasmussen, Lars M; Argraves, William S;

    2014-01-01

    BACKGROUND: Fibulin-1, a circulating extracellular matrix glycoprotein, has been associated with arterial disease and elevated N-terminal prohormone B-type natriuretic peptide (NT-proBNP) in diabetes. Soluble urokinase plasminogen activator receptor (suPAR), a marker of inflammation, has been ass...

  16. Addressing mathematics & statistics anxiety

    OpenAIRE

    Kotecha, Meena

    2015-01-01

    This paper should be of interest to mathematics and statistics educators ranging from pre-university to university education sectors. It will discuss some features of the author’s teaching model developed over her longitudinal study conducted to understand and address mathematics and statistics anxiety, which is one of the main barriers to engaging with these subjects especially in non-specialist undergraduates. It will demonstrate how a range of formative assessments are used to kindle, as w...

  17. Design and performance characteristic analysis of servo valve-type water hydraulic poppet valve

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Hwan [Pusan National University, Busan (Korea, Republic of)

    2009-09-15

    For water hydraulic system control, the flow or pressure control using high-speed solenoid valve controlled by PWM control method could be a good solution for prevention of internal leakage. However, since the PWM control of on-off valves cause extensive flow and pressure fluctuation, it is difficult to control the water hydraulic actuators precisely. In this study, the servo valve-type water hydraulic valve using proportional poppet as the main valve is designed and the performance characteristics of the servo valve-type water hydraulic valve are analyzed. Furthermore, it is demonstrated through experiments that a decline in control chamber pressure that follows the change of pilot flow is caused by the occurrence of cavitation around the proportional poppet, and that fundamental characteristics of the developed valve remain unaffected by the occurrence of cavitation

  18. Percutaneous implantation of CoreValve aortic prostheses in patients with a mechanical mitral valve.

    Science.gov (United States)

    Bruschi, Giuseppe; De Marco, Federico; Oreglia, Jacopo; Colombo, Paola; Fratto, Pasquale; Lullo, Francesca; Paino, Roberto; Frigerio, Maria; Martinelli, Luigi; Klugmann, Silvio

    2009-11-01

    Concerns exist in the field of transcatheter aortic valve implantation regarding the treatment of patients with mechanical mitral valve for possible interference between the percutaneous aortic valve and the mechanical mitral prosthesis. We report our experience with percutaneous aortic valve implantation in 4 patients with severe aortic stenosis, previously operated on for mitral valve replacement with a mechanical prosthesis. All patients underwent uneventful percutaneous retrograde CoreValve implantation (CoreValve Inc, Irvine, CA). No deformation of the nitinol tubing of the prostheses (ie, neither distortion nor malfunction of the mechanical valve in the mitral position) occurred in any of the patients. All patients are alive and asymptomatic at a mean follow-up of 171 days.

  19. Design and testing of magnetorheological valve with fast force response time and great dynamic force range

    Science.gov (United States)

    Kubík, M.; Macháček, O.; Strecker, Z.; Roupec, J.; Mazůrek, I.

    2017-04-01

    The paper deals with design, simulation and experimental testing of a magnetorheological (MR) valve with short response time. The short response time is achieved by a suitable design of an active zone in combination with use of a ferrite material for magnetic circuit. The magneto-static model and the simplified hydraulic model of the MR valve are examined and experimentally verified. The development the MR valve achieves an average response time 4.1 ms and the maximum dynamic force range of eight.

  20. DEAP actuator and its high voltage driver for heating valve application

    DEFF Research Database (Denmark)

    Huang, Lina; Nørmølle, L. F.; Sarban, R.;

    2014-01-01

    Due to the advantages of DEAP (Dielectric Electro Active Polymer) material, such as light weight, noise free operation, high energy and power density and fast response speed, it can be applied in a variety of applications to replace the conventional transducers or actuators. This paper introduces...... DEAP actuator to the heating valve system and conducts a case study to discuss the feasible solution in designing DEAP actuator and its driver for heating valve application. First of all, the heating valves under study are briefly introduced. Then the design and the development for DEAP actuator...

  1. Imaging of Cardiac Valves by Computed Tomography

    Directory of Open Access Journals (Sweden)

    Gudrun Feuchtner

    2013-01-01

    Full Text Available This paper describes “how to” examine cardiac valves with computed tomography, the normal, diseased valves, and prosthetic valves. A review of current scientific literature is provided. Firstly, technical basics, “how to” perform and optimize a multislice CT scan and “how to” interpret valves on CT images are outlined. Then, diagnostic imaging of the entire spectrum of specific valvular disease by CT, including prosthetic heart valves, is highlighted. The last part gives a guide “how to” use CT for planning of transcatheter aortic valve implantation (TAVI, an emerging effective treatment option for patients with severe aortic stenosis. A special focus is placed on clinical applications of cardiac CT in the context of valvular disease.

  2. 3D Printed Multimaterial Microfluidic Valve

    Science.gov (United States)

    Patrick, William G.; Sharma, Sunanda; Kong, David S.; Oxman, Neri

    2016-01-01

    We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics. PMID:27525809

  3. Two-Year Outcomes in Patients With Severe Aortic Valve Stenosis Randomized to Transcatheter Versus Surgical Aortic Valve Replacement

    DEFF Research Database (Denmark)

    Søndergaard, Lars; Steinbrüchel, Daniel Andreas; Ihlemann, Nikolaj

    2016-01-01

    BACKGROUND: The Nordic Aortic Valve Intervention (NOTION) trial was the first to randomize all-comers with severe native aortic valve stenosis to either transcatheter aortic valve replacement (TAVR) with the CoreValve self-expanding bioprosthesis or surgical aortic valve replacement (SAVR), inclu...... population. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01057173....

  4. STUDY ON FLUID THICKNESS BETWEEN POPPET AND VALVE GUIDE IN CONTROL VALVE OF INJECTOR

    Institute of Scientific and Technical Information of China (English)

    Zhang Jianming; Zhang Weigang; Wang Yawei

    2004-01-01

    The physical model of -20 diesel oil and force model of injector control valve of common rail system is built. The changes of the fluid thickness are investigated on the base of the results of CFD and experiments for control valve of injector. The results indicate that a fluid thickness of 0.02~0.03 mm between the poppet and valve guide is sufficient to dampen any excessive control valve poppet bouncing.

  5. An analysis of check valve performance characteristics based on valve design

    Energy Technology Data Exchange (ETDEWEB)

    McElhaney, K.L. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.

    2000-04-01

    Although it had been theorized by nuclear industry valve experts that the two most significant factors in assessing check valve performance were valve type (or design) and operating conditions, until recently, no data was available to support their assumptions. In co-operation with the Nuclear Industry Check Valve Group (NIC), Oak Ridge National Laboratory (ORNL) undertook a review and analysis of check valve failures recorded in the Institute of Nuclear Power Operations' (INPO) Nuclear Plant Reliability Data System (NPRDS). This study involved the characterization of failures according to several parameters, including valve design (e.g. swing check, lift check). Since the valve design is not inherently included within the NPRDS engineering record for each component in the database, ORNL relied on input from NIC, valve manufacturers and catalogs to supply the missing information. As a result, nearly 60% of the 21000 check valves listed in the NPRDS component database and 85% of the 838 failures occurring during 1991-1992 were identified according to valve design. This data provided the basis to perform previously unavailable cross-correlations between parameters such as valve design versus failure mode, valve design versus failure discovery method, population/failure distributions by valve design, etc. Performance assessments and predictions based on more specific sets of parameters (as opposed to generic check valve failure rates obtained from standard reference sources that generally ignore the valve design) should result in a significant impact on future nuclear plant operations, including inservice testing (IST) practices, maintenance, and probabilistic risk assessments (PRAs) by providing a means to calculate more appropriate relative (and ultimately absolute) failure rates for check valves. (orig.)

  6. Improved valve and dash-pot assembly

    Science.gov (United States)

    Chang, S.C.

    1985-04-23

    A dash-pot valve comprises a cylinder submerged in the fluid of a housing and have a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with targentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  7. Valve and dash-pot assembly

    Science.gov (United States)

    Chang, Shih-Chih

    1986-01-01

    A dash-pot valve comprising a cylinder submerged in the fluid of a housing and having a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with tangentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  8. Check valve slam analysis in pumping station

    Science.gov (United States)

    Himr, D.; Habán, V.; Dokoupil, P.

    2016-03-01

    Pumping station supplies water for technological process. The check valve in the station was replaced with a new one. The regular test of black out discovered the high pressure pulsations accompanied with noticeable pipeline movement of discharge pipe. It was caused by late check valve closing, probably, when the back flow reached the highest possible velocity. This statement was supported with analysis of results of pressure measurement near the check valve and with a numerical simulation of the flow in the pipeline system.

  9. Low-Pressure-Drop Shutoff Valve

    Science.gov (United States)

    Thornborrow, John

    1994-01-01

    Flapper valve remains open under normal flow conditions but closes upon sudden increases to high rate of flow and remains closed until reset. Valve is fluid/mechanical analog of electrical fuse or circuit breaker. Low-pressure-drop shutoff valve contains flapper machined from cylindrical surface. During normal flow conditions, flapper presents small cross section to flow. (Useful in stopping loss of fluid through leaks in cooling systems.)

  10. Bistable (latching) solenoid actuated propellant isolation valve

    Science.gov (United States)

    Wichmann, H.; Deboi, H. H.

    1979-01-01

    The design, fabrication, assembly and test of a development configuration bistable (latching) solenoid actuated propellant isolation valve suitable for the control hydrazine and liquid fluorine to an 800 pound thrust rocket engine is described. The valve features a balanced poppet, utilizing metal bellows, a hard poppet/seat interface and a flexure support system for the internal moving components. This support system eliminates sliding surfaces, thereby rendering the valve free of self generated particles.

  11. Workshop on gate valve pressure locking and thermal binding

    Energy Technology Data Exchange (ETDEWEB)

    Brown, E.J.

    1995-07-01

    The purpose of the Workshop on Gate Valve Pressure Locking and Thermal Binding was to discuss pressure locking and thermal binding issues that could lead to inoperable gate valves in both boiling water and pressurized water reactors. The goal was to foster exchange of information to develop the technical bases to understand the phenomena, identify the components that are susceptible, discuss actual events, discuss the safety significance, and illustrate known corrective actions that can prevent or limit the occurrence of pressure locking or thermal binding. The presentations were structured to cover U.S. Nuclear Regulatory Commission staff evaluation of operating experience and planned regulatory activity; industry discussions of specific events, including foreign experience, and efforts to determine causes and alleviate the affects; and valve vendor experience and recommended corrective action. The discussions indicated that identifying valves susceptible to pressure locking and thermal binding was a complex process involving knowledge of components, systems, and plant operations. The corrective action options are varied and straightforward.

  12. Avaliação da atividade elétrica atrial em pacientes submetidos ao tratamento cirúrgico da valvopatia mitral Evaluation of atrial electrical activity in patients operated on mitral valve disease

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Ferreira

    2002-01-01

    . The classical right lateral subseptal access may sometimes provide difficult exposure, so that alternative approaches are used whose effects on atrial electrical activity are contradictory. OBJECTIVE:To standardize an investigative method to evaluate heart electrical activity post-op. METHODS: Ten consecutive adult patients with mitral valve disease were operated on. Surface electrocardiogram and continuous electrocardiographic monitoring (Holter system pre and post-op., and epicardical cardioestimulation post-op. were used to study cardiac electric activity. RESULTS: There was no mortality. All patients with sinus rhythm presented supraventricular ectopia, with episodes of supraventricular tachycardia in 57%, atrial flutter in 10%, and junctional rhythm in 10%. All patients presented ventricular ectopia, with a low incidence in 70% of them and with unsustained ventricular tachycardia in 30%. During the postoperative period there was a 40% rate of new supraventricular arrhythmias (atrial fibrillation, junctional rhythm, low atrial rhythm, and paroxistic supraventricular tachycardia, with no ventricular arrhythmias. Post-op. sinus node function was preserved. There was a significant reduction of supraventricular ectopia, with reversal of atrial fibrillation to sinus rhythm in one patient. Although there was a significant reduction in left atrium size post-op, P wave duration, as well as ventricular ectopia rate remained unchanged. Interatrial conduction time correlated with left atrium size measured pre and post-op. CONCLUSION: The methods proved useful to evaluate atrial electric activity in patients operated upon by the classic subseptal access, thus permitting future comparisons with other surgical approaches to the mitral valve.

  13. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease

    NARCIS (Netherlands)

    Yap, Sing-Chien; Drenthen, Willem; Pieper, Petronella G.; Moons, Philip; Mulder, Barbara J. M.; Klieverik, Loes M.; Vliegen, Hubert W.; van Dijk, Arie P. J.; Meijboom, Folkert J.; Roos-Hesselink, Jolien W.

    Background and aim of the study: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  14. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease.

    NARCIS (Netherlands)

    Yap, S.C.; Drenthen, W.; Pieper, P.G.; Moons, P.; Mulder, B.J.M.; Klieverik, L.M.; Vliegen, H.W.; Dijk, A.P.J. van; Meijboom, F.J.; Roos-Hesselink, J.W.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  15. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease

    NARCIS (Netherlands)

    Yap, Sing-Chien; Drenthen, Willem; Pieper, Petronella G.; Moons, Philip; Mulder, Barbara J. M.; Klieverik, Loes M.; Vliegen, Hubert W.; van Dijk, Arie P. J.; Meijboom, Folkert J.; Roos-Hesselink, Jolien W.

    2007-01-01

    Background and aim of the study: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve replacem

  16. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease.

    NARCIS (Netherlands)

    Yap, S.C.; Drenthen, W.; Pieper, P.G.; Moons, P.; Mulder, B.J.M.; Klieverik, L.M.; Vliegen, H.W.; Dijk, A.P.J. van; Meijboom, F.J.; Roos-Hesselink, J.W.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve replacem

  17. Transapical JenaValve in a patient with mechanical mitral valve prosthesis.

    LENUS (Irish Health Repository)

    O' Sullivan, Katie E

    2014-01-29

    We report the first case of transcatheter aortic valve replacement implantation using JenaValve™ in a patient with mechanical mitral valve prosthesis. We believe that the design features of this valve may be particularly suited for use in this setting. © 2014 Wiley Periodicals, Inc.

  18. Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

    DEFF Research Database (Denmark)

    Aagaard, Jan; Geha, Alexander S.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area...

  19. Matching flow characteristics of standard shutoff valves eliminates need for custom fabricated valves

    Science.gov (United States)

    Bevan, A. F.

    1966-01-01

    Standard high pressure valves are used in low pressure fluid system testing when a substantial system pressure increase is required. The flow-vs-valve stroke is matched with that of the valves being replaced. Some correction to the plug contour may be necessary.

  20. New-onset atrial fibrillation after surgical aortic valve replacement and transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Jørgensen, Troels Højsgaard; Thygesen, Julie Bjerre; Thyregod, Hans Gustav;

    2015-01-01

    Surgical aortic valve replacement (SAVR) and, more recently, transcatheter aortic valve implantation (TAVI) have been shown to be the only treatments that can improve the natural cause of severe aortic valve stenosis. However, after SAVR and TAVI, the incidence of new-onset atrial fibrillation...

  1. New-Onset Atrial Fibrillation After Surgical Aortic Valve Replacement and Transcatheter Aortic Valve Implantation

    DEFF Research Database (Denmark)

    Jørgensen, Troels Højsgaard; Thygesen, Julie Bjerre; Thyregod, Hans Gustav;

    2015-01-01

    Surgical aortic valve replacement (SAVR) and, more recently, transcatheter aortic valve implantation (TAVI) have been shown to be the only treatments that can improve the natural cause of severe aortic valve stenosis. However, after SAVR and TAVI, the incidence of new-onset atrial fibrillation...

  2. Repositioning of an Intraventricular Dislocated Aortic Valve during Transcatheter Aortic Valve Implantation

    NARCIS (Netherlands)

    Natour, Ehsan; Douglas, Yvonne L.; Jainandunsing, Jayant S.; Schurer, Remco A. J.; van der Werf, Hendrik W.; van den Heuvel, Ad F. M.

    2014-01-01

    The case is presented of a 75-year-old man referred for transcatheter aortic valve implantation. During the procedure the prosthetic aortic valve became dislocated into the left ventricle shortly after expansion. The subsequent steps taken to reposition the valve using only materials at hand are des

  3. New-Onset Atrial Fibrillation After Surgical Aortic Valve Replacement and Transcatheter Aortic Valve Implantation

    DEFF Research Database (Denmark)

    Jørgensen, Troels Højsgaard; Thygesen, Julie Bjerre; Thyregod, Hans Gustav

    2015-01-01

    Surgical aortic valve replacement (SAVR) and, more recently, transcatheter aortic valve implantation (TAVI) have been shown to be the only treatments that can improve the natural cause of severe aortic valve stenosis. However, after SAVR and TAVI, the incidence of new-onset atrial fibrillation...

  4. Hydraulic engine valve actuation system including independent feedback control

    Science.gov (United States)

    Marriott, Craig D

    2013-06-04

    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

  5. Bioreactors addressing diabetes mellitus.

    Science.gov (United States)

    Minteer, Danielle M; Gerlach, Jorg C; Marra, Kacey G

    2014-11-01

    The concept of bioreactors in biochemical engineering is a well-established process; however, the idea of applying bioreactor technology to biomedical and tissue engineering issues is relatively novel and has been rapidly accepted as a culture model. Tissue engineers have developed and adapted various types of bioreactors in which to culture many different cell types and therapies addressing several diseases, including diabetes mellitus types 1 and 2. With a rising world of bioreactor development and an ever increasing diagnosis rate of diabetes, this review aims to highlight bioreactor history and emerging bioreactor technologies used for diabetes-related cell culture and therapies.

  6. Safety significance of inadvertent operation of motor operated valves in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ruger, C.J.; Higgins, J.C.; Carbonaro, J.F.; Hall, R.E.

    1994-05-01

    This report addresses concerns about the consequences of valve mispositioning which were brought to the forefront following an event at Davis Besse in 1985 (NRC, 1985a). The concern related to the ability to reposition ``position changeable`` motor operated valves (MOVs) in the event of their inadvertent operation from the control room and was documented in Nuclear Regulatory Commission (NRC) Bulletin 85-03 (NRC, 1985b) and Generic Letter (GL) 89-10 (NRC, 1989). The mispositioned MOVs may not be able to be returned to their required position due to high differential pressure (dP) or high flow conditions across the valves. The inability to reposition such valves may have significant safety consequences as in the Davis Besse event. However, full consideration of such mispositioning in safety analyses and in MOV test programs can be labor intensive and expensive. Industry raised concerns that consideration of position changeable valves under GL 89-10 would not decrease the probability of core damage to an extent which would justify licensee costs. As a response, Brookhaven National Laboratory (BNL) has conducted separate scoping studies for both Boiling Water Reactors (BWRS) and Pressurized Water Reactors (PWRs) using Probabilistic Risk Assessment (PRA) techniques to determine if such valve mispositioning by itself is significant to safety. The approach utilized internal events PRA models to survey the order of magnitude of the risk significance of valve mispositioning by considering the failure of selected position changeable MOVS. The change in core damage frequency (CDF) was determined for each valve considered and the results were presented as a risk increase ratio for each of four assumed MOV failure rates. The risk increase ratios resulting from this failure rate sensitivity study can be used as a basis for a judgement determination of the risk significance of the MOV mispositioning issue for BWRs and PWRS.

  7. Improving the pneumatic control valve performance using a PID controller

    OpenAIRE

    Heidari, Mohammad; Homaei, Hadi

    2014-01-01

    Pneumatic control valves are still the most used in process industries due to their low cost and simplicity. This paper presents a design procedure of a PID controller for a pneumatic control valve. For comparison, P and PI controllers are also utilized for the control valve. The bond graph method is used to model the control valve, in order to compare the response characteristics of the valve. Simulation results are found for three controllers of the valve. The integral time absolute error c...

  8. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    Directory of Open Access Journals (Sweden)

    Abulon DJ

    2015-09-01

    Full Text Available Dina Joy Abulon,1 Martin Charles,2 Daniel E Charles21Global Medical Affairs, Alcon Laboratories, Inc., Lake Forest, CA, USA; 2Centro Oftalmológico Dr Charles, Buenos Aires, ArgentinaPurpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP, fluid leakage, and vitreous incarceration during simulated vitrectomy.Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes.Results: In the air-filled model, IOP loss was 89%–94% when two non-valved cannulas were unoccupied versus 1%–5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%–30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P<0.005, and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P<0.05 and 27-gauge (P<0.05 non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas.Conclusion: Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy.Keywords: IOP, fluid leakage, vitreous incarceration

  9. Transaortic aortic valve replacement using the Edwards Sapien-XT Valve and the Medtronic CoreValve: initial experience.

    Science.gov (United States)

    Spargias, Konstantinos; Bouboulis, Nikolaos; Halapas, Antonios; Chrissoheris, Michael; Skardoutsos, Spyridon; Nikolaou, Joulia; Tsolakis, Apostolos; Mourmouris, Christos; Pattakos, Stratis

    2014-01-01

    Transcatheter aortic valve replacement (TAVR) is now an established treatment for certain patients with severe aortic valve stenosis (AS). However, as the number of patients screened for TAVR increases, many are found to have absolutely no option for peripheral artery access. Transaortic valve replacement (TAoVR) has been proposed as a new alternative route in patients deemed unsuitable for conventional approaches. We present our first series of TAoVR cases using the Edwards Sapien-XT and the Medtronic CoreValve prostheses. Twenty-five (25) symptomatic patients (mean age 78 ± 8 years, mean logistic EuroSCORE I 25 ± 11%) with severe AS underwent TAoVR using the Sapien-XT valve (10 patients) or the CoreValve (15 patients). The mean fluoroscopy time was 15.6 ± 4.2 minutes, the mean time in the intensive care unit was 1.9 ± 1.0 days, and the mean hospital stay was 6.4 ± 1.6 days. The mean effective aortic valve area increased (from 0.68 ± 0.15 cm(2) to 1.82 ± 0.34 cm(2), pMedtronic CoreValve prosthesis demonstrated that it could be performed safely, resulting in substantial acute echocardiographic and early clinical improvement.

  10. Transcatheter valve-in-valve implantation due to severe aortic regurgitation in a degenerated aortic homograft

    DEFF Research Database (Denmark)

    Olsen, Lene Kjaer; Engstrøm, Thomas; Søndergaard, Lars

    2009-01-01

    Transcatheter aortic valve implantation (TAVI) in severe aortic stenosis has proven to be a feasible and effective treatment modality for inoperable patients. Until now, neither aortic regurgitation nor degenerated bioprostheses has been an indication for TAVI. However, this article reports...... a successful valve-in-valve implantation of a CoreValve aortic valve prosthesis through the right subclavian artery in a case of severe aortic regurgitation within a degenerated aortic homograft. The case exemplifies the possibilities of expanding the indications for TAVI, as well as other vascular access...

  11. Infective Endocarditis of the Aortic Valve with Anterior Mitral Valve Leaflet Aneurysm.

    Science.gov (United States)

    Tomsic, Anton; Li, Wilson W L; van Paridon, Marieke; Bindraban, Navin R; de Mol, Bas A J M

    2016-08-01

    Mitral valve leaflet aneurysm is a rare and potentially devastating complication of aortic valve endocarditis. We report the case of a 48-year-old man who had endocarditis of the native aortic valve and a concomitant aneurysm of the anterior mitral valve leaflet. Severe mitral regurgitation occurred after the aneurysm perforated. The patient showed no signs of heart failure and completed a 6-week regimen of antibiotic therapy before undergoing successful aortic and mitral valve replacement. In addition to the patient's case, we review the relevant medical literature.

  12. Gasoline New Timing and Flux Adjustable Rotary Valve Design (Hereinafter: Rotary Valve

    Directory of Open Access Journals (Sweden)

    Du huiqi

    2016-01-01

    Full Text Available Conventional gasoline engine with an umbrella valve control cylinder intake and exhaust, in order to achieve sealing effect, the valve is driven by the spring force; at the same time, when the cam opens the valve to overcome the spring force acting. Sealing the better, the more power consumed in the engine mechanical losses, the valve mechanism consumes about 30%, which is not a small loss! This article describes a new type of rotary valve is to significantly reduce mechanical losses, so as to achieve energy saving purposes.

  13. Aortic and Mitral Valve Replacement Through a Single Transverse Aortotomy: A Useful Approach in Difficult Mitral Valve Exposure

    OpenAIRE

    Carmichael, Michael J.; Cooley, Denton A.; Favor, Arsenio S.

    1983-01-01

    Replacement of the mitral valve through a standard vertical left atriotomy in patients requiring both aortic and mitral valve replacement can be very difficult. This is especially true in patients who have undergone previous median sternotomy. Replacement of the mitral valve through the aortic root after excision of the aortic valve is described in two case reports. This is a convenient approach when traditional exposure of the mitral valve is impractical in patients requiring double valve re...

  14. Disruption of silicone valve housing in a Codman Hakim Precision valve with integrated Siphonguard.

    Science.gov (United States)

    Woerdeman, Peter A; Cochrane, David D

    2014-05-01

    Authors of this report describe 2 patients who had undergone shunt insertion for hydrocephalus and who, at 6 weeks or 9 months after their last revision, presented with symptoms of shunt dysfunction and CSF collections at the valve site. At the ensuing shunt revision in both patients, the silicone housing was fractured and the Siphonguard was disconnected from the Codman Hakim Precision flat-bottom valve. The cause of these failures was not clear since manipulation, bending, and twisting of the valves were not thought to have occurred during implantation. A review of the FDA's Manufacturer and User Facility Device Experience (MAUDE) database revealed 58 cases of silicone housing failure in the Codman Hakim Precision valve with integrated Siphonguard since the year 2000. A single report was found in the databases administered by the Canadian Medical Devices Sentinel Network (CMDSNet). The Codman Hakim Precision valves with integrated Siphonguard are delicate devices that do not withstand the intraoperative handling tolerated by other valves. When these valves are implanted, gentle handling and wide exposures are needed to minimize the risk of valve damage. Valves should be handled according to the manufacturer's instructions. However, in light of this particular pattern of failure, it is recommended that the manufacturer redesign this valve to provide handling tolerance that is characteristic of other valves on the market. The featured cases illustrate the importance of the surgeon's role in postmarket surveillance of medical devices and reporting device failures to the responsible agencies and manufacturers.

  15. Promoting healthy eating, active play and sustainability consciousness in early childhood curricula, addressing the Ben10™ problem: a randomised control trial.

    Science.gov (United States)

    Skouteris, Helen; Edwards, Susan; Rutherford, Leonie; Cutter-MacKenzie, Amy; Huang, Terry; O'Connor, Amanda

    2014-06-03

    This paper details the research protocol for a study funded by the Australian Research Council. An integrated approach towards helping young children respond to the significant pressures of '360 degree marketing' on their food choices, levels of active play, and sustainability consciousness via the early childhood curriculum is lacking. The overall goal of this study is to evaluate the efficacy of curriculum interventions that educators design when using a pedagogical communication strategy on children's knowledge about healthy eating, active play and the sustainability consequences of their toy food and toy selections. This cluster-randomised trial will be conducted with 300, 4 to 5 year-old children attending pre-school. Early childhood educators will develop a curriculum intervention using a pedagogical communication strategy that integrates content knowledge about healthy eating, active play and sustainability consciousness and deliver this to their pre-school class. Children will be interviewed about their knowledge of healthy eating, active play and the sustainability consequences of their food and toy selections. Parents will complete an Eating and Physical Activity Questionnaire rating their children's food preferences, digital media viewing and physical activity habits. All measures will be administered at baseline, the end of the intervention and 6 months post intervention. Informed consent will be obtained from all parents and the pre-school classes will be allocated randomly to the intervention or wait-list control group. This study is the first to utilise an integrated pedagogical communication strategy developed specifically for early childhood educators focusing on children's healthy eating, active play, and sustainability consciousness. The significance of the early childhood period, for young children's learning about healthy eating, active play and sustainability, is now unquestioned. The specific teaching and learning practices used by early

  16. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  17. Left atrial ball valve thrombus

    Directory of Open Access Journals (Sweden)

    R. Balaji

    2013-10-01

    Full Text Available "Ball valve thrombus" which is a spherical free floating clot in left atrium is an often quoted, but uncommonly encountered complication in patients with severe mitral stenosis of rheumatic origin, who are in atrial fibrillation. We describe the case of a 31-year-old lady with rheumatic heart disease, severe mitral stenosis and moderately severe aortic stenosis who had undergone closed mitral valvotomy 13 years ago. The patient presented with an episode of non-exertional syncope and breathlessness on exertion of 6 months duration and was in normal sinus rhythm. Echocardiography facilitated ante-mortem diagnosis and prompt institution of surgery was life saving.

  18. On-pump fibrillating heart mitral valve replacement with the SAPIEN™ XT transcatheter heart valve.

    Science.gov (United States)

    Ferrari, Enrico; Niclauss, Lars; Locca, Didier; Marcucci, Carlo

    2014-04-01

    In some high-risk patients, standard mitral valve replacement can represent a challenging procedure, requiring a risky extensive decalcification of the annulus. In particular, high-risk redo patients and patients with a previously implanted transcatheter aortic valve, who develop calcific mitral disease, would benefit from the development of new, minimally invasive, transcatheter or hybrid techniques for mitral valve replacement. In particular, mixing transcatheter valve therapies and well-established minimally invasive techniques for mitral replacement or repair can help in decreasing the surgical risk and the technical complexity. Thus, placing transcatheter, balloon-expandable Sapien™ XT stent-valves in calcified, degenerated mitral valves through a right thoracotomy, a left atriotomy and on an on-pump fibrillating heart, represents an attractive alternative to standard surgery in redo patients, in patients with concomitant transcatheter aortic stent-valves in place and in patients with a high-risk profile. We describe this hybrid technique in detail.

  19. Predictors of mortality after aortic valve replacement

    NARCIS (Netherlands)

    Tjang, Yanto Sandy; van Hees, Yvonne; Koerfer, Reiner; Grobbee, Diederick E.; van der Heijden, Geert J. M. G.

    Aortic valve replacement (AVR) is recommended as a standard surgical procedure for aortic valve disease. Still the evidence for commonly claimed predictors of post-AVR prognosis, in particular mortality, appears scant. This systematic review reports on the evidence for predictors of post-AVR

  20. Numerical Analysis of Large Diameter Butterfly Valve

    Science.gov (United States)

    Youngchul, Park; Xueguan, Song

    In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.

  1. 49 CFR 195.420 - Valve maintenance.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve maintenance. 195.420 Section 195.420 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each...

  2. A highly sensitive spin-valve transistor

    NARCIS (Netherlands)

    Erve, van 't O.M.J.; Vlutters, R.; Anil Kumar, P.S.; Kim, S.D.; Jansen, R.; Lodder, J.C.; Hadjipanayis, G.C.

    2001-01-01

    In this paper we present a spin-valve transistor made with a silicon on insulator wafer as emitter and a double sided polished Si wafer as collector. Using vacuum metal bonding we obtain a three terminal device in which a spin-valve layer is sandwiched between two Si wafers. We measure a 217% change

  3. Mitral valve repair in acquired dextrocardia.

    Science.gov (United States)

    Elmistekawy, Elsayed; Chan, Vincent; Hynes, Mark; Mesana, Thierry

    2015-10-01

    Surgical correction of valvular heart disease in patients with dextrocardia is extremely rare. We report a surgical case of mitral valve repair in a patient with acquired dextrocardia. Successful mitral valve repair was performed through a right lateral thoracotomy. We describe our surgical strategy and summarize the literature.

  4. Whole Teflon valves for handling droplets.

    Science.gov (United States)

    Cybulski, Olgierd; Jakiela, Slawomir; Garstecki, Piotr

    2016-06-21

    We propose and test a new whole-Teflon gate valve for handling droplets. The valve allows droplet plugs to pass through without disturbing them. This is possible due to the geometric design, the choice of material and lack of any pulses of flow generated by closing or opening the valve. The duct through the valve resembles a simple segment of tubing, without constrictions, change in lumen or side pockets. There are no extra sealing materials with different wettability or chemical resistance. The only material exposed to liquids is FEP Teflon, which is resistant to aggressive chemicals and fully biocompatible. The valve can be integrated into microfluidic systems: we demonstrate a complex system for culturing bacteria in hundreds of microliter droplet chemostats. The valve effectively isolates modules of the system to increase precision of operations on droplets. We verified that the valve allowed millions of droplet plugs to safely pass through, without any cross-contamination with bacteria between the droplets. The valve can be used in automating complex microfluidic systems for experiments in biochemistry, biology and organic chemistry.

  5. 46 CFR 64.67 - Shutoff valve.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Shutoff valve. 64.67 Section 64.67 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.67 Shutoff valve. A shutoff...

  6. Digital hydraulic valving system. [design and development

    Science.gov (United States)

    1973-01-01

    The design and development are reported of a digital hydraulic valving system that would accept direct digital inputs. Topics include: summary of contractual accomplishments, design and function description, valve parameters and calculations, conclusions, and recommendations. The electrical control circuit operating procedure is outlined in an appendix.

  7. Oil pipeline valve automation for spill reduction

    Energy Technology Data Exchange (ETDEWEB)

    Mohitpour, Mo; Trefanenko, Bill [Enbridge Technology Inc, Calgary (Canada); Tolmasquim, Sueli Tiomno; Kossatz, Helmut [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    Liquid pipeline codes generally stipulate placement of block valves along liquid transmission pipelines such as on each side of major river crossings where environmental hazards could cause or are foreseen to potentially cause serious consequences. Codes, however, do not stipulate any requirement for block valve spacing for low vapour pressure petroleum transportation, nor for remote pipeline valve operations to reduce spills. A review of pipeline codes for valve requirement and spill limitation in high consequence areas is thus presented along with a criteria for an acceptable spill volume that could be caused by pipeline leak/full rupture. A technique for deciding economically and technically effective pipeline block valve automation for remote operation to reduce oil spilled and control of hazards is also provided. In this review, industry practice is highlighted and application of the criteria for maximum permissible oil spill and the technique for deciding valve automation thus developed, as applied to ORSUB pipeline is presented. ORSUB is one of the three initially selected pipelines that have been studied. These pipelines represent about 14% of the total length of petroleum transmission lines operated by PETROBRAS Transporte S.A. (TRANSPETRO) in Brazil. Based on the implementation of valve motorization on these three pipeline, motorization of block valves for remote operation on the remaining pipelines is intended, depending on the success of these implementations, on historical records of failure and appropriate ranking. (author)

  8. Inexpensive tamper proof safety relief valve

    Science.gov (United States)

    Frankewich, P. A.

    1970-01-01

    Basic relief valve has added safety relief valve capability that relieves overpressure before failure can occur. It may be installed in inaccesible areas with a high degree of reliability, constructed from a variety of materials, and adapted to the user's specific application.

  9. Heart Valve Disease among Patients with Hyperprolactinaemia

    DEFF Research Database (Denmark)

    Steffensen, Charlotte; Maegbaek, Merete Lund; Laurberg, Peter;

    2012-01-01

    Increased risk of heart valve disease during treatment with certain dopamine agonists, such as cabergoline, has been observed in patients with Parkinson's disease. The same compound is used to treat hyperprolactinemia, but it is unknown whether this also associates with heart valve disease....

  10. Mitral valve disease—morphology and mechanisms

    Science.gov (United States)

    Levine, Robert A.; Hagége, Albert A.; Judge, Daniel P.; Padala, Muralidhar; Dal-Bianco, Jacob P.; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T.; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H.; Clusel, Catherine; Delling, Francesca N.; Dietz, Harry C.; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D.; Jensen, Morten O.; Jeunemaitre, Xavier P.; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R.; Mérot, Jean; Messas, Emmanuel; Milan, David P.; Neri, Tui; Norris, Russell A.; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A.; Song, Jae-Kwan; Yacoub, Magdi H.

    2016-01-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease. PMID:26483167

  11. Mitral valve disease--morphology and mechanisms.

    Science.gov (United States)

    Levine, Robert A; Hagége, Albert A; Judge, Daniel P; Padala, Muralidhar; Dal-Bianco, Jacob P; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H; Clusel, Catherine; Delling, Francesca N; Dietz, Harry C; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D; Jensen, Morten O; Jeunemaitre, Xavier P; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R; Mérot, Jean; Messas, Emmanuel; Milan, David P; Neri, Tui; Norris, Russell A; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A; Song, Jae-Kwan; Yacoub, Magdi H

    2015-12-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

  12. Transcatheter Aortic Valve Replacement in Europe

    DEFF Research Database (Denmark)

    Mylotte, Darren; Osnabrugge, Ruben L J; Windecker, Stephan;

    2013-01-01

    The authors sought to examine the adoption of transcatheter aortic valve replacement (TAVR) in Western Europe and investigate factors that may influence the heterogeneous use of this therapy.......The authors sought to examine the adoption of transcatheter aortic valve replacement (TAVR) in Western Europe and investigate factors that may influence the heterogeneous use of this therapy....

  13. Repair for acquired aortic valve disease.

    Science.gov (United States)

    Antunes, M J

    1996-10-01

    The favorable results of mitral valvuloplasty when compared with valve replacement have renewed the interest of many surgeons in aortic valve repair. However, these efforts have, for the most part, been unsuccessful. Also, the results of aortic valve replacement are usually better than those of mitral valve replacement. Yet, some patients appear to derive benefit from a conservative aortic valve procedure. The best examples are mild or moderate aortic valve disease associated with mitral valve or coronary artery disease, which constitute the primary indication for operation, where "prophylactic" aortic valve replacement does not appear justifiable. Other possible indications for aortic valvuloplasty includes patient's lack of compliance or contraindication to anticoagulation in young patients. Senile aortic stenosis, in very old patients with a small annulus, preserved leaflet morphology and nonsignificant commissural fusion should be considered for repair. However, since the procedure is not easily reproducible and the results not uniformly predictable, it cannot be recommended for generalized use. Nonetheless, experienced surgeons should be encouraged to continue these efforts.

  14. [Surgical Treatment of Prosthetic Valve Endocarditis].

    Science.gov (United States)

    Kaminishi, Yuichiro; Akutsu, Hirohiko; Sugaya, Akira; Kurumisawa, Soki; Takazawa, Ippei; Sato, Hirotaka; Muraoka, Arata; Aizawa, Kei; Ohki, Shinichi; Saito, Tsutomu; Kawahito, Koji; Misawa, Yoshio

    2015-11-01

    Between 2003 and 2014, at Jichi Medical University Hospital, 11 patients with prosthetic valve endocarditis (PVE) underwent re-operation. There was 1 in-hospital death and 2 late deaths. The cause of death was cirrhosis, heart failure and sepsis, respectively. Emergency surgery, previous double valve replacement (DVR) and Staphylococcus infection were common risk factors for all 3 cases. Two cases of patients that survived who underwent mitral valve replacement (MVR) and DVR for PVE after DVR were treated with multiple antibiotic courses for bacteremia associated with hemodialysis and colon cancer. One patient who underwent DVR after mitral valve plasty which was complicated with cerebral hemorrhage, had survived and was discharged. Of the aortic PVE patients, 2 cases of aortic valve replacement (AVR) using a mechanical valve, 1 case of aortic root replacement (ARR) using a mechanical valve, and 1 ARR using the homograft, were considered cured and never relapsed. A patient with aortic PVE, who underwent AVR after cesarean section for heart failure in birth period, has received ARR twice with the mechanical valve for recurrent pseudo-aneurysm of the left ventricular outflow tract. Since hemodialysis and colon cancer is a risk factor for recurrent PVE, it is necessary to consider the long-term administration of antibiotics after surgery.

  15. Lowering plasma cholesterol levels halts progression of aortic valve disease in mice

    Science.gov (United States)

    Miller, Jordan D.; Weiss, Robert M.; Serrano, Kristine M.; Brooks, Robert M.; Berry, Christopher J.; Zimmerman, Kathy; Young, Stephen G.; Heistad, Donald D.

    2009-01-01

    Background Treatment of hyperlipidemia produces functional and structural improvements in atherosclerotic vessels. However, the effects of treating hyperlipidemia on the structure and function of the aortic valve has been controversial, and any effects could be confounded by pleiotropic effects of hypolipidemic treatment. The goal of this study was to determine whether reducing elevated plasma lipid levels with a “genetic switch” in Reversa mice (Ldlr−/−/Apob100/100/Mttpfl/fl/Mx1Cre+/+) reduces oxidative stress, reduces proosteogenic signaling, and retards the progression of aortic valve disease. Methods and Results After 6 months of hypercholesterolemia, Reversa mice exhibited increases in superoxide, lipid deposition, myofibroblast activation, calcium deposition, and pro-osteogenic protein expression in the aortic valve. Maximum aortic valve cusp separation, as judged by echocardiography, was not altered. During an additional 6 months of hypercholesterolemia, superoxide levels, valvular lipid deposition, and myofibroblast activation remained elevated. Furthermore, calcium deposition and pro-osteogenic gene expression became more pronounced and the aortic cusp separation decreased from 0.85 ± 0.04 to 0.70 ± 0.04 mm (mean ± SE; p < 0.05). Rapid normalization of cholesterol levels at 6 months of age (by inducing expression of Cre recombinase) normalized aortic valve superoxide levels, decreased myofibroblast activation, reduced valvular calcium burden, suppressed pro-osteogenic signaling cascades, and prevented the reductions in aortic valve cusp separation. Conclusions Collectively, these data indicate that reducing plasma lipid levels by genetic inactivation of the mttp gene in hypercholesterolemic mice with early aortic valve disease normalizes oxidative stress, reduces pro-osteogenic signaling, and halts the progression of aortic valve stenosis. PMID:19433756

  16. In-Situ Radiological Surveys to Address Nuclear Criticality Safety Requirements During Remediation Activities at the Shallow Land Disposal Area, Armstrong County, Pennsylvania - 12268

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Phillip; Mihalo, Mark; Eberlin, John; Lambert, Mike [Cabrera Services (United States); Matthews, Brian [Nuclear Safety Associates (United States)

    2012-07-01

    Cabrera Services Inc. (CABRERA) is the remedial contractor for the Shallow Land Disposal Area (SLDA) Site in Armstrong County Pennsylvania, a United States (US) Army Corps of Engineers - Buffalo District (USACE) contract. The remediation is being completed under the USACE's Formerly Utilized Sites Remedial Action Program (FUSRAP) which was established to identify, investigate, and clean up or control sites previously used by the Atomic Energy Commission (AEC) and its predecessor, the Manhattan Engineer District (MED). As part of the management of the FUSRAP, the USACE is overseeing investigation and remediation of radiological contamination at the SLDA Site in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), 42 US Code (USC), Section 9601 et. seq, as amended and, the National Oil and Hazardous Substance Pollution Contingency Plan (NCP), Title 40 of the Code of Federal Regulations (CFR) Section 300.430(f) (2). The objective of this project is to clean up radioactive waste at SLDA. The radioactive waste contains special nuclear material (SNM), primarily U-235, in 10 burial trenches, Cabrera duties include processing, packaging and transporting the waste to an offsite disposal facility in accordance with the selected remedial alternative as defined in the Final Record of Decision (USACE, 2007). Of particular importance during the remediation is the need to address nuclear criticality safety (NCS) controls for the safe exhumation and management of waste containing fissile materials. The partnership between Cabrera Services, Inc. and Measutronics Corporation led to the development of a valuable survey tool and operating procedure that are essential components of the SLDA Criticality Safety and Material Control and Accountability programs. Using proven existing technologies in the design and manufacture of the Mobile Survey Cart, the continued deployment of the Cart will allow for an efficient and reliable

  17. Transcatheter aortic valve replacement in elderly patients

    Institute of Scientific and Technical Information of China (English)

    Dimytri Siqueira; Alexandre Abizaid; Magaly Arrais J.; Eduardo Sousa

    2012-01-01

    Aortic stenosis is the most common native valve disease, affecting up to 5% of the elderly population. Surgical aortic valve replacement reduces symptoms and improves survival, and is the definitive therapy in patients with symptomatic severe aortic stenosis. However, despite the good results of classic surgery, risk is markedly increased in elderly patients with co-morbidities. Transcatheter aortic valve replacement (TAVR) allows implantation of a prosthetic heart valve within the diseased native aortic valve without the need for open heart surgery and cardiopulmonary bypass, offering a new therapeutic option to elderly patients considered at high surgical risk or with contraindications to surgery. To date, several multicenter registries and a randomized trial have confirmed the safety and efficacy of TAVR in those patients. In this chapter, we review the background and clinical applications of TAVR in elderly patients.

  18. Aortic Root Enlargement or Sutureless Valve Implantation?

    Directory of Open Access Journals (Sweden)

    Nikolaos G. Baikoussis

    2016-11-01

    Full Text Available Aortic valve replacement (AVR in patients with a small aortic annulus is a challenging issue. The importance of prosthesis–patient mismatch (PPM post aortic valve replacement (AVR is controversial but has to be avoided. Many studies support the fact that PPM has a negative impact on short and long term survival. In order to avoid PPM, aortic root enlargement may be performed. Alternatively and keeping in mind that often some comorbidities are present in old patients with small aortic root, the Perceval S suturelles valve implantation could be a perfect solution. The Perceval sutureless bioprosthesis provides reasonable hemodynamic performance avoiding the PPM and providing the maximum of aortic orifice area. We would like to see in the near future the role of the aortic root enlargement techniques in the era of surgical implantation of the sutureless valve (SAVR and the transcatheter valve implantation (TAVI.

  19. Comments on compressible flow through butterfly valves

    Science.gov (United States)

    Blakenship, John G.

    In the flow analysis of process piping systems, it is desirable to treat control valves in the same way as elbow, reducers, expansions, and other pressure loss elements. In a recently reported research program, the compressible flow characteristics of butterfly valves were investigated. Fisher Controls International, Inc., manufacturer of a wide range of control valves, publishes coefficients that can be used to calculate flow characteristics for the full range of valve movement. The use is described of the manufacturer's data to calculate flow parameters as reported by the researchers who investigated compressible flow through butterfly valves. The manufacturer's data produced consistent results and can be used to predict choked flow and the pressure loss for unchoked flow.

  20. Multidisciplinary optimization of a butterfly valve.

    Science.gov (United States)

    Song, Xue Guan; Wang, Lin; Baek, Seok Heum; Park, Young Chul

    2009-07-01

    A butterfly valve is a type of flow control device, typically used to regulate fluid flow. This paper proposes a new process to meet desired needs in valve design that is characterized by the complex configuration. First, the need is identified according to the valve user/company, and then the problem is defined with a characteristic function. Second, the initial model of valve is made, and then the initial analysis including fluid and/or structural analysis is carried out to predict the fluid and/or structural performance of the valve. Third, the optimization in the form of mathematical functions, which considers single or multiple objective and/or discipline, is handled. This part includes the design of computer experiment, approximation technique, topology optimization and sizing optimization. Finally, the validation experiment is conducted based on the optimum result to verify the accuracy of the optimization. An example is provided to confirm the availability of the process proposed here.

  1. Transcatheter mitral valve implantation via transapical approach

    DEFF Research Database (Denmark)

    Sondergaard, Lars; Brooks, Matthew; Ihlemann, Nikolaj;

    2015-01-01

    OBJECTIVES: As many as 50% of patients with severe symptomatic mitral valve regurgitation are denied surgical valve replacement or repair due to high operative risk. We describe an early series of cases of transcatheter implantation with a CardiAQ™ mitral valve via a transapical approach. METHODS......: Three consecutive patients with an Society of Thoracic Surgeons (STS) mortality score of >22% were selected for transcatheter mitral valve implantation (TMVI) on compassionate grounds. All patients were elderly, had severe mitral regurgitation (MR), were in Class IV heart failure and deemed unsuitable...... bypass surgery (n = 2), severe pulmonary hypertension (n = 1) and moderate to severe chronic renal failure (n = 3). A CardiAQ mitral valve was implanted using fluoroscopy and transoesophageal (TEE) guidance via a standard transapical approach. RESULTS: Accurate prosthesis positioning and deployment...

  2. Short and long-term lifestyle coaching approaches used to address diverse participant barriers to weight loss and physical activity adherence.

    Science.gov (United States)

    Venditti, Elizabeth M; Wylie-Rosett, Judith; Delahanty, Linda M; Mele, Lisa; Hoskin, Mary A; Edelstein, Sharon L

    2014-02-12

    Individual barriers to weight loss and physical activity goals in the Diabetes Prevention Program, a randomized trial with 3.2 years average treatment duration, have not been previously reported. Evaluating barriers and the lifestyle coaching approaches used to improve adherence in a large, diverse participant cohort can inform dissemination efforts. Lifestyle coaches documented barriers and approaches after each session (mean session attendance = 50.3 ± 21.8). Subjects were 1076 intensive lifestyle participants (mean age = 50.6 years; mean BMI = 33.9 kg/m²; 68% female, 48% non-Caucasian). Barriers and approaches used to improve adherence were ranked by the percentage of the cohort for whom they applied. Barrier groupings were also analyzed in relation to baseline demographic characteristics. Top weight loss barriers reported were problems with self-monitoring (58%); social cues (58%); holidays (54%); low activity (48%); and internal cues (thought/mood) (44%). Top activity barriers were holidays (51%); time management (50%); internal cues (30%); illness (29%), and motivation (26%). The percentage of the cohort having any type of barrier increased over the long-term intervention period. A majority of the weight loss barriers were significantly associated with younger age, greater obesity, and non-Caucasian race/ethnicity (p-values vary). Physical activity barriers, particularly thought and mood cues, social cues and time management, physical injury or illness and access/weather, were most significantly associated with being female and obese (p  90% long term) and regularly reviewed self-monitoring skills. More costly approaches were used infrequently during the first 16 sessions (≤10%) but increased over 3.2 years. Behavioral problem solving approaches have short and long term dissemination potential for many kinds of participant barriers. Given minimal resources, increased attention to training lifestyle coaches in the consistent use of these

  3. Quantitative transporter proteomics by liquid chromatography with tandem mass spectrometry: addressing methodologic issues of plasma membrane isolation and expression-activity relationship.

    Science.gov (United States)

    Kumar, Vineet; Prasad, Bhagwat; Patilea, Gabriela; Gupta, Anshul; Salphati, Laurent; Evers, Raymond; Hop, Cornelis E C A; Unadkat, Jashvant D

    2015-02-01

    To predict transporter-mediated drug disposition using physiologically based pharmacokinetic models, one approach is to measure transport activity and relate it to protein expression levels in cell lines (overexpressing the transporter) and then scale these to via in vitro to in vivo extrapolation (IVIVE). This approach makes two major assumptions. First, that the expression of the transporter is predominantly in the plasma membrane. Second, that there is a linear correlation between expression level and activity of the transporter protein. The present study was conducted to test these two assumptions. We evaluated two commercially available kits that claimed to separate plasma membrane from other cell membranes. The Qiagen Qproteome kit yielded very little protein in the fraction purported to be the plasma membrane. The Abcam Phase Separation kit enriched the plasma membrane but did not separate it from other intracellular membranes. For the Abcam method, the expression level of organic anion-transporting polypeptides (OATP) 1B1/2B1 and breast cancer resistance protein (BCRP) proteins in all subcellular fractions isolated from cells or human liver tissue tracked that of Na⁺-K⁺ ATPase. Assuming that Na⁺-K⁺ ATPase is predominantly located in the plasma membrane, these data suggest that the transporters measured are also primarily located in the plasma membrane. Using short hairpin RNA, we created clones of cell lines with varying degrees of OATP1B1 or BCRP expression level. In these clones, transport activity of OATP1B1 or BCRP was highly correlated with protein expression level (r² > 0.9). These data support the use of transporter expression level data and activity data from transporter overexpressing cell lines for IVIVE of transporter-mediated disposition of drugs.

  4. Guidelines for Properly Adjustning Pressure Feedback in Systems with Over-Centre Valves

    DEFF Research Database (Denmark)

    Pedersen, Henrik Clemmensen; Andersen, Torben O.; Hansen, Michael R.

    2016-01-01

    Many mobile hydraulic systems are fitted with over centre valves for safety measures. However, it is well known that over centre valves in combination with pressure compensated flow control valves may lead to oscillatory and even unstable system behaviour. The traditional solution to overcome...... this problem is to use an over centre valve with a sufficiently low pilot ratio and/or include various damping orifices in the system. Both of these solutions are energy consuming and may decrease the control performance. An alternative approach is to use (electronic) pressure feedback — also referred...... to as active damping — to stabilise the system and damp pressure pulsations. This is not a new method, but the effect and adjustment of the filters is often misunderstood leading to incorrectly adjusted filters and degraded system performance. The focus of the current paper is therefore to explain and derive...

  5. Image compression using address-vector quantization

    Science.gov (United States)

    Nasrabadi, Nasser M.; Feng, Yushu

    1990-12-01

    A novel vector quantization scheme, the address-vector quantizer (A-VQ), is proposed which exploits the interblock correlation by encoding a group of blocks together using an address-codebook (AC). The AC is a set of address-codevectors (ACVs), each representing a combination of addresses or indices. Each element of the ACV is an address of an entry in the LBG-codebook, representing a vector-quantized block. The AC consists of an active (addressable) region and an inactive (nonaddressable) region. During encoding the ACVs in the AC are reordered adaptively to bring the most probable ACVs into the active region. When encoding an ACV, the active region is checked, and if such an address combination exists, its index is transmitted to the receiver. Otherwise, the address of each block is transmitted individually. The SNR of the images encoded by the A-VQ method is the same as that of a memoryless vector quantizer, but the bit rate is by a factor of approximately two.

  6. Transcatheter aortic valve-in-valve implantation of a CoreValve in a degenerated aortic bioprosthesis.

    Science.gov (United States)

    Bruschi, Giuseppe; DeMarco, Federico; Oreglia, Jacopo; Colombo, Paola; Fratto, Pasquale; Lullo, Francesca; Paino, Roberto; Martinelli, Luigi; Klugmann, Silvio

    2010-03-01

    In recent years percutaneous aortic valve implantation has emerged as an alternative therapy to treat patients with symptomatic aortic stenosis considered to be high-risk surgical candidates. We report our experience of a percutaneous retrograde CoreValve implantation in a 77-year-old female with aortic bioprosthesis structural degeneration. The patient underwent aortic valve replacement for aortic stenosis in 1999 with the implantation of a 23 mm Carpentier-Edwards; her last echocardiography showed a severe bioprosthesis stenosis. After evaluation by cardiac surgeons and cardiologist, considering the high risk re-do surgical procedure (Logistic Euroscore 30%) and severe comorbidities (severe pulmonary hypertension, hepatocellular carcinoma and severe osteoporosis), a percutaneous aortic valve-in-valve replacement was preferred. A successful percutaneous 26 mm CoreValve prosthesis implantation was performed with the patient awake with local anesthesia and mild sedation. The patient was discharged after 10 days of hospitalization and she is in NYHA functional class I at follow-up. Our experience, characterized by a multidisciplinary approach, necessary to offer the safest conditions and care for patients, demonstrates the feasibility of a new, promising indication for the use of a transcatheter valve implantation: percutaneous treatment of a degenerated aortic bioprosthesis.

  7. Posttraumatic tricuspid valve injury and severe tricuspid valve regurgitation.

    Science.gov (United States)

    Gucuk Ipek, Esra

    2013-09-01

    A 66-year-old male was brought to our hospital following a car accident. He had subarachnoid hemorrhage, multiple rib fractures, and left hemopneumothorax. He was referred to the Cardiology Department for elevated troponin levels (42 ng/ml, reference 0-1 ng/ml). The electrocardiogram was free of ischemia, whereas the transthoracic echocardiography revealed dilated right heart chambers, enlarged tricuspid annulus and coaptation failure of the tricuspid valvular leaflets. There was rupture on the subvalvular apparatus of the anterior leaflet of the tricuspid valve with accompanying prolapse, causing severe tricuspid valvular regurgitation. The patient did not present right ventricular failure signs and symptoms; he was referred to surgery after the resolution of associated thoracic and cranial injuries.

  8. Handwheel valve operation: assessment of four opening methods in terms of muscle loading, perceived comfort, and efficiency.

    Science.gov (United States)

    Aghazadeh, Fereydoun; Al Qaisi, Saif; Hutchinson, Francis; Ikuma, Laura

    2012-01-01

    Injuries due to manual valve handwheel operations are a major concern in the chemical process industry. Manual valves are used to start, stop, and control flow in process lines. The torque required to operate handwheels after the initial "breaking" can vary due to the size, design, and condition of the valve. This study tested four methods of turning the handwheel on a medium-sized gate valve at two different torque requirements (25 Nm and 50 Nm). The methods were compared to each other, in terms of efficiency, subjective ratings of perceived exertion, and electromyography activity of the upper extremity and trunk muscles. The results indicate that different methods and torque requirements are compensated for by the use of different muscles. Also, this use of different muscles, along with the increased mechanical advantage of the wrench, can affect the operator's actual and perceived comfort and efficiency while operating a valve handwheel.

  9. THE RESULTS OF SURGICAL TREATMENT OF TRICUSPID VALVE INFECTIVE ENDOCARDITIS USING VALVE REPAIR AND VALVE REPLACEMENT OPERATIONS

    Directory of Open Access Journals (Sweden)

    S. A. Kovalev

    2015-01-01

    Full Text Available Aim. To evaluate in-hospital and long-term results of surgical treatment of patients with infective endocarditis of the tricuspid valve, to compare the effectiveness of valve repair and valve replacement techniques, and to identify risk factors of mortality and reoperations. Materials and methods. 31 surgical patients with tricuspid valve infective endocarditis were evaluated. Patients were divided into 2 groups. In Group 1 (n = 14 repairs of the tricuspid valve were performed, in Group 2 (n = 17 patients had undergone tricuspid valve replacements. Epidemiological, clinical, microbiological and echocardiographic data were studied. Methods of comparative analysis, the Kaplan–Meier method, and Cox risk models were applied. Results. The most common complication of in-hospital stay was atrioventricular block (17.7% of cases in Group 2. In Group 1, this type of complication was not found. Hospital mortality was 7.14% in Group 1, and 0% in Group 2. Long-term results have shown the significant reduction of heart failure in general cohort and in both groups. In Group 1 the severity of heart failure in the long term was less than in Group 2. No significant differences in the severity of tricuspid regurgitation were found between the groups. In 7-year follow up no cases of death were registered in Group 1. Cumulative survival rate in Group 2 within 60 months was 67.3 ± 16.2%. No reoperations were performed in patients from Group 1. In Group 2, the freedom from reoperation within 60 months was 70.9 ± 15.3%. Combined intervention was found as predictor of postoperative mortality. Prosthetic valve endocarditis was identified as risk factor for reoperation. Conclusion. Valve repair and valve replacement techniques of surgical treatment of tricuspid valve endocarditis can provide satisfactory hospital and long-term results. Tricuspid valve repair techniques allowed reducing the incidence of postoperative atrioventricular block. In the long-term, patients

  10. Addressing psychiatric comorbidity.

    Science.gov (United States)

    Woody, G E; McLellan, A T; O'Brien, C P; Luborsky, L

    1991-01-01

    Research studies indicate that addressing psychiatric comorbidity can improve treatment for selected groups of substance-abusing patients. However, the chances for implementing the necessary techniques on a large scale are compromised by the absence of professional input and guidance within programs. This is especially true in public programs, which treat some of the most disadvantaged, disturbed, and socially destructive individuals in the entire mental health system. One starting point for upgrading the level of knowledge and training of staff members who work in this large treatment system could be to develop a better and more authoritative information dissemination network. Such a system exists in medicine; physicians are expected to read appropriate journals and to guide their treatment decisions using the data contained in the journals. Standards of practice and methods for modifying current practice are within the tradition of reading new facts, studying old ones, and comparing treatment outcome under different conditions with what is actually being done. No such general system of information-gathering or -sharing exists, particularly in public treatment programs. One of the most flagrant examples of this "educational shortfall" can be found among those methadone programs that adamantly insist on prescribing no more than 30 to 35 mg/day for all patients, in spite of the overwhelming evidence that these dose levels generally are inadequate. In some cases, program directors are unaware of studies that have shown the relationship between dose and outcome. In other cases, they are aware of the studies but do not modify their practices accordingly. This example of inadequate dosing is offered as an example of one situation that could be improved by adherence to a system of authoritative and systematic information dissemination. Many issues in substance abuse treatment do not lend themselves to information dissemination as readily as that of methadone dosing

  11. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    Energy Technology Data Exchange (ETDEWEB)

    MORGAN, R.G.

    1999-04-06

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve.

  12. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    Energy Technology Data Exchange (ETDEWEB)

    MORGAN, R.G.

    1999-04-06

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve.

  13. Modern Use of Echocardiography in Transcatheter Aortic Valve Replacement: an Up-Date.

    Science.gov (United States)

    Caldararu, Cristina; Balanescu, Serban

    2016-12-01

    Echocardiography is the cornerstone in the diagnosis of any valvular heart disease. The accurate diagnosis of aortic stenosis, the left ventricle function and the other heart valves evaluation are currently done by ultrasound alone. Prosthetic valve choice and dimensions prior to implantation can be done solely by proper use of echocardiography. The emergence of new methods to cure aortic stenosis such as trans-catheter aortic valve replacement (TAVR) emphasized the diagnostic value of cardiac ultrasound. The usefulness of echocardiography in TAVR can be divided in the baseline assessment (common to patients treated by conventional surgery), intra-procedural guidance of valve deployment and post-procedural follow-up. In the baseline diagnostic work-up echocardiography should allow proper assessment of low-gradient severe aortic stenosis and especially of "low-flow, low-gradient" aortic stenosis, as far the benefit of any valve intervention in these cases may be overshadowed by persistent ventricular dysfunction. "Classic" TAVR is performed with a trans-esophageal echocardiography probe in place, but recently intracardiac echocardiography (ICE) was advocated to reduce the need for general anesthesia. "Minimalist TAVR approach" recommends no echo-guidance and valve implantation by angiography alone. Post-TAVR echo assessment should allow prompt recognition of early complications and the severity of para-valvular leaks. Long term follow-up by echocardiography assesses prosthetic valve function, left ventricular functional recovery and the impact of the procedure on associated conditions (mitral regurgitation, pulmonary hypertension or tricuspid regurgitation). This article emphasizes the role of the cardiologist with ultrasound skills in the assessment of patients addressed to TAVR.

  14. Whitey SCHe Ball Valves Provide Test Port Isolation

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-15

    These valves are 1/4 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

  15. 49 CFR 192.181 - Distribution line valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Distribution line valves. 192.181 Section 192.181... line valves. (a) Each high-pressure distribution system must have valves spaced so as to reduce the time to shut down a section of main in an emergency. The valve spacing is determined by the...

  16. 46 CFR 105.25-20 - Shutoff valves required.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Shutoff valves required. 105.25-20 Section 105.25-20... Installed Below Decks § 105.25-20 Shutoff valves required. (a) Shutoff valves shall be provided in the suction lines as close to the tanks as possible. The valves shall be installed so as to shut off...

  17. 46 CFR 154.1125 - Pipes, fittings, and valves.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Pipes, fittings, and valves. 154.1125 Section 154.1125... Firefighting § 154.1125 Pipes, fittings, and valves. (a) Each pipe, fitting, and valve for each water spray... listed in § 154.1110 must have at least one isolation valve at each branch connection and at least...

  18. 46 CFR 154.806 - Capacity of pressure relief valves.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Capacity of pressure relief valves. 154.806 Section 154... Equipment Cargo Vent Systems § 154.806 Capacity of pressure relief valves. Pressure relief valves for each... pressure above the set pressure of the relief valves: (a) The maximum capacity of an installed cargo...

  19. 46 CFR 78.17-5 - Valves and closing appliances.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.17-5 Section 78.17-5..., Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting valves where fitted, and other appliances such...

  20. 46 CFR 153.368 - Pressure-vacuum valves.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve... relief valve must meet the requirements of Subpart 162.017 of this chapter....

  1. 46 CFR 98.25-40 - Valves, fittings, and accessories.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Valves, fittings, and accessories. 98.25-40 Section 98... Anhydrous Ammonia in Bulk § 98.25-40 Valves, fittings, and accessories. (a) All valves, flanges, fittings... Engineering) of this chapter. Valves shall be fitted with noncorrosive material suitable for ammonia...

  2. 46 CFR 56.20-9 - Valve construction.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Valve construction. 56.20-9 Section 56.20-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Valves § 56.20-9 Valve construction. (a) Each valve must close with a right-hand...

  3. Motor operated valves problems tests and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pinier, D.; Haas, J.L.

    1996-12-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  4. Heart Valve Biomechanics and Underlying Mechanobiology

    Science.gov (United States)

    Ayoub, Salma; Ferrari, Giovanni; Gorman, Robert C.; Gorman, Joseph H.; Schoen, Frederick J.; Sacks, Michael S.

    2017-01-01

    Heart valves control unidirectional blood flow within the heart during the cardiac cycle. They have a remarkable ability to withstand the demanding mechanical environment of the heart, achieving lifetime durability by processes involving the ongoing remodeling of the extracellular matrix. The focus of this review is on heart valve functional physiology, with insights into the link between disease-induced alterations in valve geometry, tissue stress, and the subsequent cell mechanobiological responses and tissue remodeling. We begin with an overview of the fundamentals of heart valve physiology and the characteristics and functions of valve interstitial cells (VICs). We then provide an overview of current experimental and computational approaches that connect VIC mechanobiological response to organ- and tissue-level deformations and improve our understanding of the underlying functional physiology of heart valves. We conclude with a summary of future trends and offer an outlook for the future of heart valve mechanobiology, specifically, multiscale modeling approaches, and the potential directions and possible challenges of research development. PMID:27783858

  5. A multicentre comparative evaluation of catheter valves.

    Science.gov (United States)

    Fader, M; Pettersson, L; Brooks, R; Dean, G; Wells, M; Cottenden, A; Malone-Lee, J

    Catheter valves are an alternative to leg bags for urine drainage, but no studies have yet been published which have compared the performance of different valves. This study was undertaken to evaluate the performance of the seven catheter valves available on the UK market in April 1996. The study was carried out by the Continence Products Evaluation (CPE) Network funded by the Medical Devices Agency (Department of Health). Each valve type was tested for 1 week by 19-36 cognitively unimpaired and manually dextrous subjects recruited from 11 test centres. At the end of each week, subjects completed an evaluation form (based on a three-point rating scale) to record product performance. The same catheter valves were also tested for ease of opening/closing by 33 subjects (mostly catheter users) who had some manual impairment. Performance scores varied widely between products. It was found that, to be successful, a valve needs to be easy to manipulate, leak-free, comfortable and inconspicuous. Prescribers need to be aware of the strengths and limitations of different valves for appropriate product selection.

  6. PRESIDENT’S ADDRESS

    Directory of Open Access Journals (Sweden)

    Lucie Kubínová

    2016-03-01

    Full Text Available Dear colleagues, Let me wish you and our Image Analysis & Stereology Journal all the best in 2016. It is great honour for me to be in charge of the International Society for Stereology (ISS. I would like to thank Eric Pirard for all his tremendous work and effort he has put into ISS activities in past years, together with all members of the ISS Board. I am glad Eric is willing to help me with ISS as „Immediate Past President“. I also rely on close collaboration with Ida Eržen and Marko Kreft, the Editors-in-Chief of Image Analysis & Stereology (IAS, IAS Editorial Board and future ISS Board. I appreciate long-term cooperation between the Image Analysis & Stereology Journal and the International Society for Stereology and I am looking forward to broaden our relationships in the future. As a President of ISS I plan to evoke new activities which would help to make ISS vivid and useful to scientific community. We are planning new courses on stereology, image analysis and related topics run in cooperation with ISS with reduced fee for ISS members, competion for the best PhD thesis using stereology and/or image analysis, ISS history mapping, etc. I welcome your further suggestions and comments. I would like to cordially invite you to become members of the International Society for Stereology (http://stereologysociety.org/membership.html and to take part in new activities organized by ISS, such as:Special Session „3D Image Analysis and Stereology in Fluorescence Microscopy“ at ISBI 2016 (in Prague, see http://biomedicalimaging.org/2016/?page_id=768.Round table discussion on „Stereology and 3D image analysis in microscopy“ to be held at the 16th European Microscopy Congress in Lyon (EMC 2016, see http://www.emc2016.fr/en/scientific-programme/special/stereology.It is my intention to involve young people and fresh ideas in the activities of ISS and in further improvement of IAS. Please contact me at lucie

  7. A novel implantable glaucoma valve using ferrofluid.

    Directory of Open Access Journals (Sweden)

    Eleftherios I Paschalis

    Full Text Available PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg. X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

  8. Address Points, Addressing, Published in 2008, Taylor County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Address Points dataset, was produced all or in part from Orthoimagery information as of 2008. It is described as 'Addressing'. Data by this publisher are often...

  9. Fluid-Structure Interaction Analysis of Papillary Muscle Forces Using a Comprehensive Mitral Valve Model with 3D Chordal Structure.

    Science.gov (United States)

    Toma, Milan; Jensen, Morten Ø; Einstein, Daniel R; Yoganathan, Ajit P; Cochran, Richard P; Kunzelman, Karyn S

    2016-04-01

    Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with [Formula: see text]CT. Experimental data from the in vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed leaflet dynamics, and force vectors from the in vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements enable validating and adjusting material parameters to improve the accuracy of computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.

  10. Film edge nonlocal spin valves.

    Science.gov (United States)

    McCallum, Andrew T; Johnson, Mark

    2009-06-01

    Spintronics is a new paradigm for integrated digital electronics. Recently established as a niche for nonvolatile magnetic random access memory (MRAM), it offers new functionality while demonstrating low-power and high-speed performance. However, to reach high density spintronic technology must make a transition to the nanometer scale. Prototype devices are presently made using a planar geometry and have an area determined by the lithographic feature size, currently about 100 nm. Here we present a new nonplanar geometry in which one lateral dimension is given by a film thickness, on the order of 10 nm. With this new approach, cell sizes can shrink by an order of magnitude. The geometry is demonstrated with a nonlocal spin valve, where we study devices with an injector/detector separation much less than the spin diffusion length.

  11. Rotary Valve FY 2016 Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Fitsos, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-07

    The fiscal year started with the Rotary Valve (RV) being reassembled after having crashed in June of 2015. The crash occurred when the RV inner surface contacted the housing. The cause of the crash was never confirmed. No particles were found in the 2.5 thousandths of an inch gap and the filters the helium gas passed through were all clean. There were marks on the bearings that looked like electrostatic discharge as shown below in Figure 1. These marks hadn’t been seen before and there were similar discharge marks on some of the ball bearings. Examples of this were found in a literature search of bearing failures. This leads to a possible cause due to this arcing affecting the rotational accuracy of the bearings driving the RV into the housing.

  12. Valve Corporation: Composing Internal Markets

    Directory of Open Access Journals (Sweden)

    Todd R. Zenger

    2015-07-01

    Full Text Available Discussions of the Valve Corporation are always enlightening. The skeptic wonders how much is rhetoric and recruiting ploy and how much is real. Is there clear evidence that this organizational design actually works – that it is efficient in this setting? While revenues per employee are quite remarkable, cause and effect are unclear. Is “boss-less-ness” the cause of high sales per employee or simply the result of high sales per employee, fueled from earlier success? The same question could be asked of Google’s unusual organizational approach. Is Google’s success the result of its extensive autonomy granted to employees, or is its past success the enabling cause of such autonomy? Such questions, of course, are empirically unanswerable here. I therefore set them aside and assume this organizational specimen is efficient – well-suited to its environment – and proceed with further commentary.

  13. Computed Flow Through An Artificial Heart Valve

    Science.gov (United States)

    Rogers, Stewart E.; Kwak, Dochan; Kiris, Cetin; Chang, I-Dee

    1994-01-01

    Report discusses computations of blood flow through prosthetic tilting disk valve. Computational procedure developed in simulation used to design better artificial hearts and valves by reducing or eliminating following adverse flow characteristics: large pressure losses, which prevent hearts from working efficiently; separated and secondary flows, which causes clotting; and high turbulent shear stresses, which damages red blood cells. Report reiterates and expands upon part of NASA technical memorandum "Computed Flow Through an Artificial Heart and Valve" (ARC-12983). Also based partly on research described in "Numerical Simulation of Flow Through an Artificial Heart" (ARC-12478).

  14. Bacillus cereus endocarditis in native aortic valve.

    Science.gov (United States)

    Ngow, H A; Wan Khairina, W M N

    2013-02-01

    Bacillus cereus endocarditis is rare. It has been implicated in immunocompromised individuals, especially in intravenous drug users as well as in those with a cardiac prosthesis. The patient was a 31-year-old ex-intravenous drug addict with a past history of staphylococcal pulmonary valve endocarditis, who presented with symptoms of decompensated cardiac failure. Echocardiography showed severe aortic regurgitation with an oscillating vegetation seen on the right coronary cusp of the aortic valve. The blood cultures grew Bacillus cereus. We report this as a rare case of Bacillus cereus endocarditis affecting a native aortic valve.

  15. Infective endocarditis following transcatheter aortic valve replacement-

    DEFF Research Database (Denmark)

    Loh, Poay Huan; Bundgaard, Henning; S�ndergaard, Lars

    2013-01-01

    Transcatheter aortic valve replacement (TAVR) can improve the symptoms and prognosis of patients with severe aortic stenosis who, due to a high expected operative risk, would not have otherwise been treated surgically. If these patients develop prosthetic valve endocarditis, their presentations may...... be atypical causing a delay in the diagnosis and treatment. The management is also complicated by their comorbidities, and surgical treatment may not be feasible leading to a significant morbidity and mortality. We describe a case of an 85-year-old man with TAVI prosthetic valve endocarditis successfully...

  16. The echocardiography of replacement heart valves

    Science.gov (United States)

    2016-01-01

    This is a practical description of how replacement valves are assessed using echocardiography. Normal transthoracic appearances including normal variants are described. The problem of differentiating normal function, patient–prosthesis mismatch and pathological obstruction in aortic replacement valves with high gradients is discussed. Obstruction and abnormal regurgitation is described for valves in the aortic, mitral and right-sided positions and when to use echocardiography in suspected infective endocarditis. The roles of transoesophageal and stress echocardiography are described and finally when other imaging techniques may be useful. PMID:27600454

  17. Combined pressure regulator and shutoff valve

    Science.gov (United States)

    Koch, E. F. (Inventor)

    1974-01-01

    A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop.

  18. [New aspects in aortic valve disease].

    Science.gov (United States)

    Tornos, P

    2001-01-01

    Renewed interest for aortic valve disease has evolved in recent years. Aortic valve replacement has become the second most frequent cause of cardiac surgery, following coronary bypass surgery. In addition, the etiologic and physiopathologic knowledge of this disorder has improved. In the present paper we analyze three aspects of the disease which are, at present, the subject of study and controversy: first, we discuss the possible relationship between degenerative aortic stenosis and atherosclerosis; second, the involvement of the aortic root in cases of bicuspid aortic valve; and third, the surgical indications in asymptomatic patients with either aortic stenosis or regurgitation.

  19. Three-dimensional echocardiography in valve disease.

    Science.gov (United States)

    Colombo, Chiara; Tamborini, Gloria; Pepi, Mauro; Alimento, Marina; Fiorentini, Cesare

    2007-01-01

    This review covers the role of three-dimensional (3D) echocardiography in the diagnosis of heart valve disease. Several factors have contributed to the evolution of this technique, which is currently a simple and routine method: rapid evolution in probe and computer technologies, demonstration that 3D data sets allowed more complete and accurate evaluation of cardiac structures, emerging clinical experience indicating the strong potential particularly in valve diseases, volume and function of the two ventricle measurements and several other fields. This report will review current and future applications of 3D echocardiography in mitral, aortic and tricuspid valve diseases underlying both qualitative (morphologic) and quantitative advantages of this technique.

  20. Spin-Valve and Spin-Tunneling Devices: Read Heads, MRAMs, Field Sensors

    Science.gov (United States)

    Freitas, P. P.

    Hard disk magnetic data storage is increasing at a steady state in terms of units sold, with 144 million drives sold in 1998 (107 million for desktops, 18 million for portables, and 19 million for enterprise drives), corresponding to a total business of 34 billion US [1]. The growing need for storage coming from new PC operating systems, INTERNET applications, and a foreseen explosion of applications connected to consumer electronics (digital TV, video, digital cameras, GPS systems, etc.), keep the magnetics community actively looking for new solutions, concerning media, heads, tribology, and system electronics. Current state of the art disk drives (January 2000), using dual inductive-write, magnetoresistive-read (MR) integrated heads reach areal densities of 15 to 23 bit/μm2, capable of putting a full 20 GB in one platter (a 2 hour film occupies 10 GB). Densities beyond 80 bit/μm2 have already been demonstrated in the laboratory (Fujitsu 87 bit/μm2-Intermag 2000, Hitachi 81 bit/μm2, Read-Rite 78 bit/μ m2, Seagate 70 bit/μ m2 - all the last three demos done in the first 6 months of 2000, with IBM having demonstrated 56 bit/μ m2 already at the end of 1999). At densities near 60 bit/μm2, the linear bit size is sim 43 nm, and the width of the written tracks is sim 0.23 μm. Areal density in commercial drives is increasing steadily at a rate of nearly 100% per year [1], and consumer products above 60 bit/μm2 are expected by 2002. These remarkable achievements are only possible by a stream of technological innovations, in media [2], write heads [3], read heads [4], and system electronics [5]. In this chapter, recent advances on spin valve materials and spin valve sensor architectures, low resistance tunnel junctions and tunnel junction head architectures will be addressed.

  1. Chemical-assisted bonding of thermoplastics/elastomer for fabricating microfluidic valves.

    Science.gov (United States)

    Gu, Pan; Liu, Ke; Chen, Hong; Nishida, Toshikazu; Fan, Z Hugh

    2011-01-01

    Thermoplastics such as cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA) have been increasingly used in fabricating microfluidic devices. However, the state-of-the-art microvalve technology is a polydimethylsiloxane (PDMS)-based three-layer structure. In order to integrate such a valve with a thermoplastics-based microfluidic device, a bonding method for thermoplastics/PDMS must be developed. We report here a method to bond COC with PDMS through surface activation by corona discharge, surface modification using 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), and thermal annealing. The method is also applicable to PMMA. The bonding strength between thermoplastics and PDMS was represented by the peeling force, which was measured using a method established by the International Organization for Standardization (ISO). The bonding strength measurement offered an objective and quantitative indicator for protocol optimization, as well as comparison with other PDMS-associated bonding methods. Using optimized bonding conditions, two valve arrays were fabricated in a COC/PDMS/COC device and cyclic operations of valve closing/opening were successfully demonstrated. The valve-containing devices withstood 100 psi (∼689 KPa) without delamination. Further, we integrated such valve arrays in a device for protein separation and demonstrated isoelectric focusing in the presence of valves.

  2. IL-10 and ET-1 as biomarkers of rheumatic valve disease

    Directory of Open Access Journals (Sweden)

    Sydney Correia Leão

    2014-03-01

    Full Text Available Objective: To evaluate the immunological profile and gene expression of endothelin-1 (ET-1 in mitral valves of patients with rheumatic fever originated from a reference service in cardiovascular surgery. Methods: This was a quantitative, observational and cross-sectional study. Thirty-five subjects (divided into four groups participated in the study, 25 patients with chronic rheumatic heart disease and ten control subjects. The mean age of the sample studied was 34.5 years. Seventeen of them (48.58% were male and 18 (51.42% were female. Inflammatory cytokines (TNF-α, IL-4 and IL-10 were measured and ten mitral valves of patients who underwent first valve replacement were collected for determination of gene expression of endothelin-1 by real time PCR. Results: Among the groups studied (patients vs. controls, there was a statistically significant difference in IL-10 levels (P=0.002, and no differences in other cytokines. Expression of endothelin-1 was observed in 70% of samples. Quantitatively, average of ET-1 expression was 62.85±25.63%. Conclusion: Inflammatory cytokine IL-10 participates in the maintenance of chronicity of rheumatic fever in patients who underwent valve replacement and those who are undergoing medical treatment. The expression of endothelin-1 in heart valve lesions in patients undergoing mitral valve replacement confirms its association with inflammatory activity in rheumatic fever.

  3. Method and apparatus for monitoring motor operated valve motor output torque and power at valve seating

    Science.gov (United States)

    Casada, Donald A.

    1996-01-01

    A method and apparatus are provided for monitoring a motor operated valve during the brief period when the valve seats and the torque switch trips to deenergize the valve motor. The method uses voltage measurements on the load side of a deenergizing switch that opens to deenergize the motor to determine, among other things, final motor rotational speed and the decelerating torque at motor deenergization.

  4. Computational Fluid Dynamics Analysis of Butterfly Valve Performance Factors

    OpenAIRE

    Del Toro, Adam

    2012-01-01

    Butterfly valves are commonly used in industrial applications to control the internal flow of both compressible and incompressible fluids. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As the valve's opening angle is increased from 0 degrees (fully closed) to 90 degrees (fully open), fluid is able to more readily flow past the valve. Characterizing a valve's performance factors, such as pressure drop, hydrodynamic torqu...

  5. Injetor multicanal com válvulas de estrangulamento para análise em fluxo Pinch valve injector for flow analysis

    Directory of Open Access Journals (Sweden)

    Fabiano S. Palgrossi

    2001-10-01

    Full Text Available An important component for the automation of flow injection analysis (FIA systems is the sample injection valve. A simple and inexpensive commutator with 16 pinch valves (8 normally open and 8 closed was developed and configured as a multichannel injection valve. It is activated by a single solenoid of 3 Kgf, powered by a pulsed driver circuit, controlled by a microcomputer or a switch. FIA with spectrophometric detection of potassium dichromate solution was used for the evaluation of the new injection valve and its comparison with other valves, for sample loops of 50, 100, 200, 300 and 500 muL. The repeatability was favorable (RSD 1.0% for 15 injections at each loop volume compared to a manual injector, an electropneumatic injector and an injector configured with three mini solenoid valves (RSD 1.1, 1.3 and 1.0%, respectively, for15 injections at each loop volume.

  6. Valve selection handbook engineering fundamentals for selecting the right valve design for every industrial flow application

    CERN Document Server

    Smith, Peter

    2004-01-01

    Valves are the components in a fluid flow or pressure system that regulate either the flow or the pressure of the fluid. They are used extensively in the process industries, especially petrochemical. Though there are only four basic types of valves, there is an enormous number of different kinds of valves within each category, each one used for a specific purpose. No other book on the market analyzes the use, construction, and selection of valves in such a comprehensive manner.-Covers new environmentally-conscious equipment and practices, the most important hot-button issue in the p

  7. Artificial SMA valve for treatment of urinary incontinence: upgrading of valve and introduction of transcutaneous transformer.

    Science.gov (United States)

    Tanaka, M; Hirano, K; Goto, H; Namima, T; Uchi, K; Jiang, Z W; Matsuki, H; Tanahashi, Y; Orikasa, S; Chonan, S

    1999-01-01

    This paper is concerned with the development of an artificial urethral valve driven by shape memory alloy actuators, which is attached onto the urethra of a urinary incontinence sufferer for treating the involuntary micturition. Three types of compact cylindrical valves are assembled and their opening and closing functions are examined experimentally. The updated valve is heated and opened by using the transcutaneous energy transformer consisting of a pair of flexible spiral-formed copper wire coils. The experiment using the canine urinary canal verifies that the total system of the valve and the transformer works well as an artificial sphictor muscle and controls the urinary flow through the canal appropriately.

  8. [Emergent transcatheter aortic valve implantation in a patient with bicuspid aortic valve stenosis in cardiogenic shock].

    Science.gov (United States)

    Pizzighini, S; Finet, G; Obadia, J-F; Revel, D; Bresson, D; Rioufol, G

    2015-02-01

    Transcatheter aortic valve implantation is a therapeutic option for high-risk patients with severe aortic valve stenosis and with cardiac symptoms. This procedure requires the preliminary evaluation by a "heart team" and presents some contraindications. We report the case of a 58-year-old man with severe bicuspid aortic valve stenosis and cardiogenic shock. In spite of contraindications and because of the failure of balloon aortic valvuloplasty, transcatheter aortic valve implantation was performed in emergency. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  9. In vitro evaluation of the iValve: a novel hands-free speech valve.

    Science.gov (United States)

    van der Houwen, Eduard B; van Kalkeren, Tjouwke A; Burgerhof, Johannes G M; van der Laan, Bernard F A M; Verkerke, Gijsbertus J

    2011-12-01

    We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops. This method makes long sentences or pauses difficult. The novel iValve is designed to allow almost natural speech, with mid-sentence pausing and whispering. The inhalation closing flows and exhalation opening pressures of 6 iValve prototype versions at different settings were compared with physiological values. The airflow resistance at inhalation was compared to physiological values and to commercial valve values. The iValve prototypes showed flow and pressure ranges in concordance with the physiological values in the literature. The airflow resistance in the breathing mode was within the physiological airflow resistance range, yet above the values from the two commercial valves. The resistance in the speaking mode was above the physiological airflow resistance range. In vitro tests show that the iValve versions can be selected and adjusted to operate within the physiological range. The airflow resistance in the breathing mode is good. In speaking mode, inhalation should, and can, be decreased. The iValve should offer the patient a more intuitively useable alternative with more dynamic speech. Its low cost allows disposability and wider use.

  10. Experimental study on wear failure course of gas-valve/valve-seat in engine

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yun-cai; YAN Hang-zhi

    2005-01-01

    The wear failure course of gas-valve/valve-seat in engine was investigated with a simulating tester. The results show that the failure of the contact conical surface is mainly caused by the elastic and plastic deformation and the fatigue micro-crack and spalling. The creep-deformation and corrosion atmosphere accelerated wear failure course at the high temperature. The wear failure course of the gas-valve/valve-seat in engine follows general wear rules of mechanical elements, but the rate of wear in the sharp wear stage is faster.

  11. Recellularization of decellularized heart valves: Progress toward the tissue-engineered heart valve

    Science.gov (United States)

    VeDepo, Mitchell C; Detamore, Michael S; Hopkins, Richard A; Converse, Gabriel L

    2017-01-01

    The tissue-engineered heart valve portends a new era in the field of valve replacement. Decellularized heart valves are of great interest as a scaffold for the tissue-engineered heart valve due to their naturally bioactive composition, clinical relevance as a stand-alone implant, and partial recellularization in vivo. However, a significant challenge remains in realizing the tissue-engineered heart valve: assuring consistent recellularization of the entire valve leaflets by phenotypically appropriate cells. Many creative strategies have pursued complete biological valve recellularization; however, identifying the optimal recellularization method, including in situ or in vitro recellularization and chemical and/or mechanical conditioning, has proven difficult. Furthermore, while many studies have focused on individual parameters for increasing valve interstitial recellularization, a general understanding of the interacting dynamics is likely necessary to achieve success. Therefore, the purpose of this review is to explore and compare the various processing strategies used for the decellularization and subsequent recellularization of tissue-engineered heart valves. PMID:28890780

  12. Mitral Valve Replacement with a Mechanical Valve for Severe Mitral Regurgitation in a Small Dog

    Directory of Open Access Journals (Sweden)

    Daisuke Taguchi

    2014-01-01

    Full Text Available A seven-year-old Shih Tzu with refractory repeated pulmonary edema and syncope was presented for surgical operation. From the results of cardiovascular examinations, the dog was diagnosed as severe mitral regurgitation (ACVIM consensus class D and mild tricuspid regurgitation. The dog first underwent surgery with mitral valve plasty; however, the results were unsatisfactory due to severe damage of the whole mitral valve. The operation was quickly changed to mitral valve replacement using a mechanical valve (19 mm. The dog survived surgery and lived for 2 years and one month after operation using long-term anticoagulant (warfarin therapy in spite of several thrombosis-related events.

  13. Basis of valve operator selection for SMART

    Energy Technology Data Exchange (ETDEWEB)

    Kang, H. S.; Lee, D. J.; See, J. K.; Park, C. K.; Choi, B. S

    2000-05-01

    SMART, an integral reactor with enhanced safety and operability, is under development for use of the nuclear energy. The valve operator of SMART system were selected through the data survey and technical review of potential valve fabrication vendors, and it will provide the establishment and optimization of the basic system design of SMART. In order to establish and optimize the basic system design of SMART, the basis of selection for the valve operator type were provided based on the basic design requirements. The basis of valve operator selection for SMART will be used as a basic technical data for the SMART basic and detail design and a fundamental material for the new reactor development in the future.

  14. Valve Technology Arrangement of Cryopump: A Review

    Directory of Open Access Journals (Sweden)

    Sanjiv Y. Rajput

    2014-05-01

    Full Text Available A cryopump or a "cryogenic pump" is a vacuum pump that pumps the trap gases and vapours by condensing them on a cold surface. Helium gas which is very light can only be pumped by Cryopump. Cryopump cannot be used when working for continuous operation as it pumps the effluent till the saturation state is achieved. Then the absorbed gases are to be collected through other mechanical pump through regeneration process. Hence, valve technology arrangement is incorporated with the cryopump in order to achieve the continuous pumping when two cryopump are used in alternate processes (i.e. absorption and regeneration. Various design of Valve technology arrangement is proposed by different researcher all over the world. This review paper focuses on the different proposed valve technology arrangement and elaborately explains the various components of valve technology and concludes the best possible arrangement that can be used in Cryopump.

  15. Heritable retinoblastoma and accelerated aortic valve disease

    Science.gov (United States)

    Abeyratne, L R; Kingston, J E; Onadim, Z; Dubrey, S W

    2013-01-01

    Heritable retinoblastoma is associated with a germline mutation in the tumour suppressor gene RBI. The Rb protein (pRb) arises from the RB1 gene, which was the first demonstrated cancer susceptibility gene in humans. 1 Second primary malignancies are recognised complications of retinoblastoma. Furthermore, pRb is implicated in valve remodelling in calcific aortic valve disease. 2 3 We report a family with hereditary retinoblastoma and associated secondary primary malignancies. There are two interesting aspects to this family. The first is the concept of ‘cancer susceptibility genes’; the RBI gene being the first reported in humans. A further feature of note is that two family members also have bicuspid aortic valves. We discuss a potential association between the gene defect responsible for retinoblastoma (with its associated propensity for further malignancies) and accelerated deterioration of the bicuspid aortic valve in the proband carrying this gene defect. PMID:23595191

  16. Simulation of a Hydraulic Pump Control Valve

    Science.gov (United States)

    Molen, G. Vander; Akers, A.

    1987-01-01

    This paper describes the mode of operation of a control valve assembly that is used with a hydraulic pump. The operating system of the valve is modelled in a simplified form, and an analogy for hydraulic resonance of the pressure sensing system is presented. For the control valve investigated, air entrainment, length and diameter of the resonator neck, and valve mass produced the greatest shift in resonant frequency. Experimental work was conducted on the hydraulic system so that the resonance levels and frequencies could be measured and the accuracy of the theory verified. The results obtained make it possible to evaluate what changes to any of the variables considered would be most effective in driving the second harmonic frequency above the operating range.

  17. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. ...

  18. VOST Flow-Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A cryogenic flow-control valve based on Venturi-Offset Technology (VOST) will be designed and modeled. VOST provides precise linear flow control within a...

  19. Low-Mass VOST Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A cylindrical, low-mass, high-efficiency, leak-proof cryogenic valve will be designed using composites and exotic metals. Based upon cryogenically-proven Venturi...

  20. VOST Flow-Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two cryogenic flow-control valves of diameters 1/2" and 2" will be built and tested. Based on cryogenically-proven Venturi Off-Set Technology (VOST) they have no...

  1. Glovebox pressure relief and check valve

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1986-03-17

    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  2. Contamination avoidance devices for poppettype shutoff valves

    Science.gov (United States)

    Endicott, D. L.

    1973-01-01

    The determination of the cycle life is reported of the scal closure of a typical poppet-type shutoff valve in an uncontaminated GH2 environment and then compared this component performance with simulated operation with GN2 and LN2 containing controlled amounts of AL2O3 contaminant particles. The original valve design was tested for contamination damage tolerance characteristics under full-flow and cyclic-operating conditions, redesigned to improve the damage tolerance to contaminants, and then retested. The redesigned valve was found to have acceptable tolerance characteristics under all full-flow conditions and cyclic operation with small (25-75 microns) particulate contamination. The tolerance characteristics of the valve under cyclic conditions with large (75-250 microns) particulate contamination was improved but was not found to be completely satisfactory.

  3. Surgical Treatment of Congenital Mitral Valve Dysplasia.

    Science.gov (United States)

    Vida, Vladimiro L; Carrozzini, Massimiliano; Padalino, Massimo; Milanesi, Ornella; Stellin, Giovanni

    2016-05-01

    Congenital mitral valve (MV) dysplasia is a relatively rare and highly complex cardiac disease. We present our results and illustrate the techniques used to repair these valves. Between 1972 and 2014, 100 consecutive patients underwent surgical repair of congenital MV dysplasia at our institution. Predominant MV regurgitation was present in 53 patients (53%) whereas mitral stenosis was prevalent in 47 (47%). There were five early (5%) and eight late deaths (9%). Actuarial survival was 95%, 94%, and 93% at 5, 10, and 20 years, respectively. Sixteen patients (18%) required reintervention due to subsequent MV dysfunction. Actuarial freedom from reintervention for MV dysfunction was 95%, 92%, and 89% at 5, 10, and 20 years, respectively. The mechanism underlying the valve dysfunction in congenital mitral valve dysplasia is multifactorial and requires the application of a variety of surgical techniques for repair. doi: 10.1111/jocs.12743 (J Card Surg 2016;31:352-356). © 2016 Wiley Periodicals, Inc.

  4. Electrodynamic actuators for rocket engine valves

    Science.gov (United States)

    Fiet, O.; Doshi, D.

    1972-01-01

    Actuators, employed in acoustic loudspeakers, operate liquid rocket engine valves by replacing light paper cones with flexible metal diaphragms. Comparative analysis indicates better response time than solenoid actuators, and improved service life and reliability.

  5. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Piezoelectric actuators constructed with the "smart material" PZT offer many potential advantages for use in NASA cryo-valve missions relative to conventional...

  6. Percutaneous Valvuloplasty for Bioprosthetic Tricuspid Valve Stenosis

    Science.gov (United States)

    Malhotra, Rohit; Sharma, Anjali; Kakouros, Nikolaos

    2017-01-01

    Percutaneous transcatheter tricuspid balloon valvuloplasty (PTTBV) is an accepted treatment option for symptomatic severe native tricuspid valve stenosis, although surgical tricuspid valve replacement remains the treatment of choice. There have been few reports of successful PTTBV for bioprosthetic tricuspid valve stenosis. We present case reports of 3 patients from our hospital experience. Two of the 3 cases were successful, with lasting clinical improvement, whereas the 3rd patient failed to show a reduction in valve gradient. We describe the standard technique used for PTTBV. We present results from a literature review that identified 16 previously reported cases of PTTBV for bioprosthetic severe tricuspid stenosis, with overall favorable results. We conclude that PTTBV should perhaps be considered for a select patient population in which symptomatic improvement and hemodynamic stability are desired immediately, and particularly for patients who are inoperable or at high surgical risk.

  7. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. ...

  8. Computed Tomography of Prosthetic Heart Valves

    NARCIS (Netherlands)

    Habets, J.

    2012-01-01

    Prosthetic heart valve (PHV) dysfunction is an infrequent but potentially life-threatening disease with a heterogeneous clinical presentation. Patients with PHV dysfunction clinically can present with symptoms of congestive heart failure (dyspnea, fatigue, edema), fever, angina pectoris, dizziness d

  9. Low-Mass VOST Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two low-mass, linear throttling, high-efficiency, leak-proof cryogenic valves of diameters 1/2" and 4" will be built and tested. Based upon cryogenically-proven...

  10. Transcatheter Aortic Valve Replacement in a Patient With a Previous Bioprosthetic Mitral Valve Replacement: Report of a Delayed Fatal Interaction.

    Science.gov (United States)

    Poulin, Frédéric; Lamarche, Yoan; Le, Van Hoai Viet; Doucet, Michel; Roméo, Philippe; Généreux, Philippe

    2016-02-01

    We report on a man with bioprosthetic mitral valve perforation who presented late after transcatheter aortic valve replacement with a balloon-expandable transcatheter heart valve (THV). The protrusion of the commissural strut of the bioprosthetic mitral valve coupled with the low implanted THV resulted in repetitive trauma leading to rupture of a mitral leaflet. Potential preventive strategies are discussed. This case illustrates the importance of preprocedural imaging screening and cautious THV deployment in patients with a bioprosthetic mitral valve.

  11. Magnetic hydrogel nanocomposites as remote controlled microfluidic valves.

    Science.gov (United States)

    Satarkar, Nitin S; Zhang, Wenli; Eitel, Richard E; Hilt, J Zach

    2009-06-21

    In recent years, hydrogels have attracted attention as active components in microfluidic devices. Here, we present a demonstration of remote controlled flow regulation in a microfluidic device using a hydrogel nanocomposite valve. To create the nanocomposite hydrogel, magnetic nanoparticles were dispersed in temperature-responsive N-isopropylacrylamide (NIPAAm) hydrogels. The swelling and collapse of the resultant nanocomposite can be remotely controlled by application of an alternating magnetic field (AMF). A ceramic microfluidic device with Y-junction channels was fabricated using low temperature co-fired ceramic (LTCC) technology. The nanocomposite was incorporated as a valve in one of the channels of the device. An AMF of frequency 293 kHz was then applied to the device and ON-OFF control on flow was achieved. A pressure transducer was placed at the inlet of the channel and pressure measurements were done for multiple AMF ON-OFF cycles to evaluate the reproducibility of the valve. Furthermore, the effect of the hydrogel geometry on the response time was characterized by hydrogels with different dimensions. Magnetic hydrogel nanocomposite films of different thicknesses (0.5, 1, 1.5 mm) were subjected to AMF and the kinetics of collapse and recovery were studied.

  12. Dynamic heart phantom with functional mitral and aortic valves

    Science.gov (United States)

    Vannelli, Claire; Moore, John; McLeod, Jonathan; Ceh, Dennis; Peters, Terry

    2015-03-01

    Cardiac valvular stenosis, prolapse and regurgitation are increasingly common conditions, particularly in an elderly population with limited potential for on-pump cardiac surgery. NeoChord©, MitraClipand numerous stent-based transcatheter aortic valve implantation (TAVI) devices provide an alternative to intrusive cardiac operations; performed while the heart is beating, these procedures require surgeons and cardiologists to learn new image-guidance based techniques. Developing these visual aids and protocols is a challenging task that benefits from sophisticated simulators. Existing models lack features needed to simulate off-pump valvular procedures: functional, dynamic valves, apical and vascular access, and user flexibility for different activation patterns such as variable heart rates and rapid pacing. We present a left ventricle phantom with these characteristics. The phantom can be used to simulate valvular repair and replacement procedures with magnetic tracking, augmented reality, fluoroscopy and ultrasound guidance. This tool serves as a platform to develop image-guidance and image processing techniques required for a range of minimally invasive cardiac interventions. The phantom mimics in vivo mitral and aortic valve motion, permitting realistic ultrasound images of these components to be acquired. It also has a physiological realistic left ventricular ejection fraction of 50%. Given its realistic imaging properties and non-biodegradable composition—silicone for tissue, water for blood—the system promises to reduce the number of animal trials required to develop image guidance applications for valvular repair and replacement. The phantom has been used in validation studies for both TAVI image-guidance techniques1, and image-based mitral valve tracking algorithms2.

  13. Tenecteplase in prosthetic mitral valve thrombosis

    OpenAIRE

    2010-01-01

    In the few reported cases of prosthetic mitral valve thrombosis, where surgical intervention was considered as high risk, fibrinolytic therapy had proved life saving. The authors present clinical, laboratory, and imaging data from such a patient, with prosthetic mitral valve thrombosis and its successful management with tenecteplase. The use of tenecteplase as a viable fibrinolytic agent for the first time was justified, due to the lack of immunogenicity concerns compared to streptokinase.

  14. Tenecteplase in prosthetic mitral valve thrombosis.

    Science.gov (United States)

    Ayyub Ghori, Masood; Bakir, Sherif; Ellahham, Samer; Al Nassir, Adnan; Al Zubaidi, Abdulmajeed; Augustin, Norbert; Abdelaziz, Moataz Ayman; Turrin, Nicolas Patrick; Al Mahmeed, Wael Abdulrahman

    2011-04-01

    In the few reported cases of prosthetic mitral valve thrombosis, where surgical intervention was considered as high risk, fibrinolytic therapy had proved life saving. The authors present clinical, laboratory, and imaging data from such a patient, with prosthetic mitral valve thrombosis and its successful management with tenecteplase. The use of tenecteplase as a viable fibrinolytic agent for the first time was justified, due to the lack of immunogenicity concerns compared to streptokinase.

  15. Symptomatic papillary tumour of the pulmonary valve

    OpenAIRE

    Cooper, Linda Carol

    1982-01-01

    Papillary ‘tumours’ are small pedunculated lesions of the valve cusps and result from wear-and-tear. They are therefore frequent post-mortem findings in older patients. The vast majority are clinically silent, though occasionally such lesions when on the aortic valve may produce symptoms of myocardial or cerebral ischaemia. None has been known to cause symptoms when in the right side of the heart.

  16. Reconstructive surgery of the aortic valve

    Directory of Open Access Journals (Sweden)

    Mendonça José Teles de

    2003-01-01

    Full Text Available OBJECTIVE: Lacking an ideal valve substitute and motivated by the good results of mitral valve repair since 1990, we faced with determination aortic valve reconstruction surgery. The objective of this paper is to show our experience with this procedure. METHOD: Between January of 1990 and December of 2001; 136 aortic valve repair surgeries were performed. Seventy-five (55.1% of the patients were female and the ages ranged from 4 to 70 years (mean 23.3 ± 1.2 years. Every patient had rheumatic valve disease and insufficiency was the most prevalent type (108 patients - 79.4%, followed by double aortic lesion in 16 (11.7% patients and stenosis in 12 (8.8%. The surgical techniques used were: subcommissural annuloplasty in 74 (54.4% patients, commissurotomy in 38 (27.9%, cusp extension with pericardium in 17 (12.5%, substitution of one cusp in 2 (1.4%, cusp suspension by annuloplasty in 37 (27.2% and Valsalva sinus remodeling in 27 (19.8%. The surgery exclusively involved the aortic valve in 57 (41.9% patients and was associated in 79 (mitral valve replacement in 12, mitral repair in 65, coronary artery bypass grafting in 1 and pulmonary commissurotomy in 1. RESULTS: Hospital mortality was 2.2% and 22 (16.2% patients underwent a new surgery during the follow-up period (57.7 ± 3.5 months. CONCLUSIONS: Aortic valve repair is a safe surgical procedure that can be used in an increasing number of patients with promising results.

  17. DIAGNOSTICS AND TREATMENT OF MITRAL VALVE PROLAPSE

    Directory of Open Access Journals (Sweden)

    D. A. Kuzhel

    2010-01-01

    Full Text Available The mitral valve prolapse (MVP is one of the most inconsistent diagnose. In the most cases patients with MVP have the good long-term prognosis, and therapy is aimed at reduction in psychovegetative dysfunction. Careful follow-up and timely cardiosurgical correction should be performed, if necessary, in patients with classical MPV. The choice method in these cases is the mitral valve plasty.

  18. Refuge alternatives relief valve testing and design.

    Science.gov (United States)

    Lutz, T J; Bissert, P T; Homce, G T; Yonkey, J A

    2016-10-01

    The U.S. National Institute for Occupational Safety and Health (NIOSH) has been researching refuge alternatives (RAs) since 2007. RAs typically have built-in pressure relief valves (PRVs) to prevent the unit from reaching unsafe pressures. The U.S. Mine Safety and Health Administration requires that these valves vent the chamber at a maximum pressure of 1.25 kPa (0.18 psi, 5.0 in. H2O), or as specified by the manufacturer, above mine atmospheric pressure in the RA. To facilitate PRV testing, an instrumented benchtop test fixture was developed using an off-the-shelf centrifugal blower and ductwork. Relief pressures and flow characteristics were measured for three units: (1) a modified polyvinyl chloride check valve, (2) an off-the-shelf brass/cast-iron butterfly check valve and (3) a commercially available valve that was designed specifically for one manufacturer's steel prefabricated RAs and had been adapted for use in one mine operator's built-in-place RA. PRVs used in tent-style RAs were not investigated. The units were tested with different modifications and configurations in order to check compliance with Title 30 Code of Federal Regulations, or 30 CFR, regulations. The commercially available relief valve did not meet the 30 CFR relief pressure specification but may meet the manufacturer's specification. Alternative valve designs were modified to meet the 30 CFR relief pressure specification, but all valve designs will need further design research to examine survivability in the event of a 103 kPa (15.0 psi) impulse overpressure during a disaster.

  19. Fibrinolytic therapy for mechanical pulmonary valve thrombosis.

    Science.gov (United States)

    Khajali, Zahra; Mohammadzadeh, Shabnam; Maleki, Majid; Peighambari, Mohammad Mehdi; Sadeghpoor, Anita; Ghavidel, Alireza; Elahi, Behrad; Mirzaaghayan, Mohammadreza

    2015-01-01

    Treatment of prosthetic heart valve thrombosis using intravenous thrombolytics, although an acceptable alternative to surgery, is not complication free, and the literature has a dearth of data on the subject. This study analyzed the results of fibrinolytic treatment (FT) among a single-center group of patients with mechanical pulmonary valve thrombosis. Between 2000 and 2013, 23 consecutive patients with 25 episodes of pulmonary valve thrombosis received FT. The diagnosis of mechanical pulmonary valve thrombosis was established by fluoroscopy and echocardiography. Streptokinase (SK) was used in 24 cases and alteplase in 1 case. The FT was continued a second day for 14 patients (58.3%), a third day for 1 patient, and a fourth day for 1 patient. Echocardiography and fluoroscopy were performed every day until improvement of malfunction was achieved. Of the 23 patients, 19 had complete resolution of hemodynamic abnormalities after FT, 1 had partial resolution, and 2 showed no change. No patient had major complications. Five minor complications were detected, namely, fever, nausea, thrombophlebitis, epistaxi, and pain. Seven patients (30%) experienced recurrence of thrombosis, whereas four patients had surgery (biological pulmonary valve replacement) without re-thrombolytic therapy, one patient was treated with Alteplase, one patient received SK, and one patient received intense anticoagulation using heparin and warfarin. Overall, FT had a success rate of 84%. The results indicate that regardless of the time to pulmonary valve replacement and echocardiographic and fluoroscopic findings, FT was effective in most cases of mechanical pulmonary valve thrombosis. The efficacy increased with second-day thrombolytic therapy. Major complications were not common after lytic therapy for mechanical pulmonary valve thrombosis.

  20. Native valve Escherichia coli endocarditis following urosepsis.

    Science.gov (United States)

    Rangarajan, D; Ramakrishnan, S; Patro, K C; Devaraj, S; Krishnamurthy, V; Kothari, Y; Satyaki, N

    2013-05-01

    Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure.

  1. Synchronous intra-myocardial ventricular pacing without crossing the tricuspid valve or entering the coronary sinus

    Energy Technology Data Exchange (ETDEWEB)

    Konecny, Tomas; DeSimone, Christopher V.; Friedman, Paul A.; Bruce, Charles [Department of Medicine, Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Asirvatham, Samuel J., E-mail: asirvatham.samuel@mayo.edu [Department of Medicine, Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Department of Pediatric and Adolescent Medicine, Pediatric Cardiology, Mayo Clinic, Rochester, MN (United States)

    2013-05-15

    Ventricular pacing is most commonly performed at the right ventricular (RV) apex. This is not without risk as placement requires crossing the tricuspid valve (TV) and may cause valvular dysfunction and dyssynchronous activation of the ventricles. The fact that the tricuspid valve lies more apically than the mitral valve allows for the possibility of pacing the ventricles from the right atrium (RA) via the “atrio-ventricular septum” without crossing the TV or entering the coronary sinus (CS). In order to mitigate far field activation inherent to current pacing technology, we constructed a novel lead in which the cathode and anode are both intra-myocardial. We demonstrate safety and efficacy of this novel lead for ventricular pacing at the atrio-ventricular septum in canines, including improved synchronous activation of both ventricles, improved differentiation in ventricular versus atrial sensing, while providing reliable ventricular capture, opening novel and a potentially safer alternative to human cardiac resynchronization therapy.

  2. Europa Propulsion Valve Seat Material Testing

    Science.gov (United States)

    Addona, Brad M.

    2017-01-01

    The Europa mission and spacecraft design presented unique challenges for selection of valve seat materials that met the fluid compatibility requirements, and combined fluid compatibility and high radiation exposure level requirements. The Europa spacecraft pressurization system valves will be exposed to fully saturated propellant vapor for the duration of the mission. The effects of Nitrogen Tetroxide (NTO) and Monomethylhydrazine (MMH) propellant vapors on heritage valve seat materials, such as Vespel SP-1 and Polychlorotrifluoroethylene (PCTFE), were evaluated to determine if an alternate material is required. In liquid system applications, Teflon is the only available compatible valve seat material. Radiation exposure data for Teflon in an air or vacuum environment has been previously documented. Radiation exposure data for Teflon in an oxidizer environment such as NTO, was not available, and it was unknown whether the effects would be similar to those on air-exposed samples. Material testing was conducted by Marshall Space Flight Center (MSFC) and White Sands Test Facility (WSTF) to determine the effects of propellant vapor on heritage seat materials for pressurization valve applications, and the effects of combined radiation and NTO propellant exposure on Teflon. The results indicated that changes in heritage pressurization valve seat materials' properties rendered them unsuitable for the Europa application. The combined radiation and NTO exposure testing of Teflon produced results equivalent to combined radiation and air exposure results.

  3. 2D DIGITAL SIMPLIFIED FLOW VALVE

    Institute of Scientific and Technical Information of China (English)

    Ruan Jian; Li Sheng; Pei Xiang; Burton R; Ukrainetz P; Bitner D

    2004-01-01

    The 2D digital simplified flow valve is composed of a pilot-operated valve designed with both rotary and linear motions of a single spool,and a stepper motor under continual control.How the structural parameters affect the static and dynamic characteristics of the valve is first clarified and a criterion for stability is presented.Experiments are designed to test the performance of the valve.It is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless,it is possible to maintain the dynamic response at a fairly high level,while keeping the leakage of the pilot stage at an acceptable level.One of the features of the digital valve is stage control.In stage control the nonlinearities,such as electromagnetic saturation and hysteresis,are greatly reduced.To a large extent the dynamic response of the valve is decided by the executing cycle of the control algorithm.

  4. Pulmonary-Valve Replacement in Adults: Results With the Medtronic Freestyle Valve.

    Science.gov (United States)

    Ramanan, Sowmya; Doll, Nicolas; Boethig, Dietmar; Tafer, Nadir; Horke, Alexander; Roques, Xavier; Hemmer, Wolfgang Bruno; Roubertie, François

    2015-09-01

    We used the Medtronic Freestyle valve (Medtronic, Minneapolis, MN) as an orthotopic conduit in pulmonary valve replacement in repaired tetralogy of Fallot and as part of the Ross procedure. Midterm outcomes and hemodynamic status of this conduit were analyzed and performances in both subgroups were compared. From February 2002 to July 2012, 115 Freestyle valves were implanted in 52 patients with tetralogy of Fallot and 63 patients within the Ross procedure. Preoperative and perioperative data were reviewed retrospectively in this bicentric study. Mean age at valve surgery was 37 ± 13 years. Median implanted valve size was 27 mm (21 to 29). Early postoperative mortality was 3.48%. There was 100% follow-up for the survivors at a mean of 4.38 ± 2.52 years. There was 1 case of thromboembolism (0.89%), 6 endocarditis (5.4%), and 9 (7.8%) conduit re-interventions. Echocardiography at discharge and last follow-up showed average peak systolic transvalvular gradients of 12.4 ± 5.1 and 18.7 ± 8.8 mm Hg, respectively. Ten patients had significant proximal anastomotic gradients of greater than 50 mm Hg and 4 moderate conduit regurgitations. Survival was 96.52%. No valve degeneration was seen in 87.82% at 5 years. The only risk factor identified for valve re-intervention was conduit implantation without infundibular hood (p = 0.01 in multivariate analysis). Mid-term data show that Freestyle valves are well suited for pulmonary valve replacement in adults in both categories. The surgical technique used in valve implantation is important to ensure conduit durability. These results and accessibility to the Freestyle valve make this an acceptable alternative to homografts. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  5. Electromechanically Actuated Valve for Controlling Flow Rate

    Science.gov (United States)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  6. Shape Memory Actuated Normally Open Permanent Isolation Valve

    Science.gov (United States)

    Ramspacher, Daniel J. (Inventor); Bacha, Caitlin E. (Inventor)

    2017-01-01

    A valve assembly for an in-space propulsion system includes an inlet tube, an outlet tube, a valve body coupling the inlet tube to the outlet tube and defining a propellant flow path, a valve stem assembly disposed within the valve body, an actuator body coupled to the valve body, the valve stem assembly extending from an interior of the valve body to an interior of the actuator body, and an actuator assembly disposed within the actuator body and coupled to the valve stem assembly, the actuator assembly including a shape memory actuator member that when heated to a transition temperature is configured to enable the valve stem assembly to engage the outlet tube and seal the propellant flow path.

  7. The prognosis of infective endocarditis treated with biological valves versus mechanical valves: A meta-analysis.

    Science.gov (United States)

    Tao, Ende; Wan, Li; Wang, WenJun; Luo, YunLong; Zeng, JinFu; Wu, Xia

    2017-01-01

    Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves. Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis. A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520). The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in the clinical features of patients

  8. Aortic valve sclerosis in mice deficient in endothelial nitric oxide synthase

    Science.gov (United States)

    El Accaoui, Ramzi N.; Gould, Sarah T.; Hajj, Georges P.; Chu, Yi; Davis, Melissa K.; Kraft, Diane C.; Lund, Donald D.; Brooks, Robert M.; Doshi, Hardik; Zimmerman, Kathy A.; Kutschke, William; Anseth, Kristi S.; Heistad, Donald D.

    2014-01-01

    Risk factors for fibrocalcific aortic valve disease (FCAVD) are associated with systemic decreases in bioavailability of endothelium-derived nitric oxide (EDNO). In patients with bicuspid aortic valve (BAV), vascular expression of endothelial nitric oxide synthase (eNOS) is decreased, and eNOS−/− mice have increased prevalence of BAV. The goal of this study was to test the hypotheses that EDNO attenuates profibrotic actions of valve interstitial cells (VICs) in vitro and that EDNO deficiency accelerates development of FCAVD in vivo. As a result of the study, coculture of VICs with aortic valve endothelial cells (vlvECs) significantly decreased VIC activation, a critical early phase of FCAVD. Inhibition of VIC activation by vlvECs was attenuated by NG-nitro-l-arginine methyl ester or indomethacin. Coculture with vlvECs attenuated VIC expression of matrix metalloproteinase-9, which depended on stiffness of the culture matrix. Coculture with vlvECs preferentially inhibited collagen-3, compared with collagen-1, gene expression. BAV occurred in 30% of eNOS−/− mice. At age 6 mo, collagen was increased in both bicuspid and trileaflet eNOS−/− aortic valves, compared with wild-type valves. At 18 mo, total collagen was similar in eNOS−/− and wild-type mice, but collagen-3 was preferentially increased in eNOS−/− mice. Calcification and apoptosis were significantly increased in BAV of eNOS−/− mice at ages 6 and 18 mo. Remarkably, these histological changes were not accompanied by physiologically significant valve stenosis or regurgitation. In conclusion, coculture with vlvECs inhibits specific profibrotic VIC processes. In vivo, eNOS deficiency produces fibrosis in both trileaflet and BAVs but produces calcification only in BAVs. PMID:24610917

  9. Transcatheter aortic valve implantation vs. surgical aortic valve replacement for treatment of severe aortic stenosis

    DEFF Research Database (Denmark)

    Siontis, George C M; Praz, Fabien; Pilgrim, Thomas

    2016-01-01

    AIMS: In view of the currently available evidence from randomized trials, we aimed to compare the collective safety and efficacy of transcatheter aortic valve implantation (TAVI) vs. surgical aortic valve replacement (SAVR) across the spectrum of risk and in important subgroups. METHODS AND RESULTS...

  10. Transcatheter Aortic Valve Replacement With Early- and New-Generation Devices in Bicuspid Aortic Valve Stenosis

    DEFF Research Database (Denmark)

    Yoon, Sung-Han; Lefèvre, Thierry; Ahn, Jung-Ming

    2016-01-01

    BACKGROUND: Few studies have evaluated the clinical outcomes of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (AS). Particularly, limited data exist comparing the results of TAVR with new-generation devices versus early-generation devices. OBJECTIVE...

  11. 40 CFR 60.483-1 - Alternative standards for valves-allowable percentage of valves leaking.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Alternative standards for valves-allowable percentage of valves leaking. 60.483-1 Section 60.483-1 Protection of Environment ENVIRONMENTAL... Before November 7, 2006 § 60.483-1 Alternative standards for valves—allowable percentage of...

  12. Single-centre experience with mitral valve repair in asymptomatic patients with severe mitral valve regurgitation

    NARCIS (Netherlands)

    W.J. van Leeuwen (Wouter); S.J. Head (Stuart); L.E. de Groot-de Laat (Lotte); M.L. Geleijnse (Marcel); A.J.J.C. Bogers (Ad); L.A. van Herwerden (Lex); A.P. Kappetein (Arie Pieter)

    2013-01-01

    textabstractOBJECTIVES: Guidelines recommend surgical mitral valve repair in selected patients with asymptomatic severe mitral valve regurgitation (MR), but the role of repair remains a matter of debate. Survival analyses of operated asymptomatic patients have been reported, but long-term haemodynam

  13. In Vitro Evaluation of the iValve : A Novel Hands-Free Speech Valve

    NARCIS (Netherlands)

    van der Houwen, E.B.; van Kalkeren, T.A.; Burgerhof, J.G.; van der Laan, B.F.; Verkerke, G.J.

    2011-01-01

    Objectives: We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure

  14. Replacing the valve restoring the flow: Effects of transcatheter aortic valve implantation

    NARCIS (Netherlands)

    Wiegerinck, E.M.A.

    2016-01-01

    When conventional surgery is not an option due to high surgical risk, transcatheter aortic valve implantation (TAVI) is a firmly established alternative and an effective and safe treatment option in this patient population. This thesis focuses on treatment of aortic valve stenosis by TAVI. The aim i

  15. Idiopathic mitral valve prolapse with tricuspid, aortic and pulmonary valve involvement: An autopsy case report

    Directory of Open Access Journals (Sweden)

    Heena M Desai

    2015-01-01

    Full Text Available Mitral valve prolapse (MVP is usually asymptomatic, but can be associated with complications such as infective endocarditis, mitral regurgitation, thromboembolism and sudden cardiac death. It has been very rarely reported to occur in association with other valvular involvement. A 55-year-old male patient was brought dead and at autopsy the mitral valve orifice was stenotic and the leaflets were enlarged, myxoid and bulging suggestive of MVP and chordae tendinae were thickened, stretched and elongated. Similar changes were seen in the tricuspid valve. The pulmonary and aortic valves also showed myxomatous degeneration of their cusps. Myxomatous degeneration is the most common cause of MVP and it can be associated with involvement of the other valves. Concomitant involvement of the aortic valve has been reported, however it is very rare and simultaneous involvement of the pulmonary valve has not been reported in the literature so far. We report a case of MVP associated with myxomatous degeneration of the tricuspid, pulmonary and aortic valves.

  16. In Vitro Evaluation of the iValve : A Novel Hands-Free Speech Valve

    NARCIS (Netherlands)

    van der Houwen, E.B.; van Kalkeren, T.A.; Burgerhof, J.G.; van der Laan, B.F.; Verkerke, G.J.

    2011-01-01

    Objectives: We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops

  17. 12 CFR 5.52 - Change of address.

    Science.gov (United States)

    2010-01-01

    ... CORPORATE ACTIVITIES Other Changes in Activities and Operations § 5.52 Change of address. (a) Authority. 12... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Change of address. 5.52 Section 5.52 Banks and... notify the OCC of any change in its address. However, no notice is required if the change in...

  18. Anonymous-address-resolution model

    Institute of Scientific and Technical Information of China (English)

    Guang-jia SONG; Zhen-zhou JI

    2016-01-01

    Address-resolution protocol (ARP) is an important protocol of data link layers that aims to obtain the corresponding relationship between Internet Protocol (IP) and Media Access Control (MAC) addresses. Traditional ARPs (address-resolution and neighbor-discovery protocols) do not consider the existence of malicious nodes, which reveals destination addresses in the resolution process. Thus, these traditional protocols allow malicious nodes to easily carry out attacks, such as man-in-the-middle attack and denial-of-service attack. To overcome these weaknesses, we propose an anonymous-address-resolution (AS-AR) protocol. AS-AR does not publicize the destination address in the address-resolution process and hides the IP and MAC addresses of the source node. The malicious node cannot obtain the addresses of the destination and the node which initiates the address resolution; thus, it cannot attack. Analyses and experiments show that AS-AR has a higher security level than existing security methods, such as secure-neighbor discovery.

  19. Advanced microbial check valve development

    Science.gov (United States)

    Colombo, G. V.; Greenley, D. R.

    1980-01-01

    A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through the device. The device is equally effective for fluid flow in either direction and its primary method of organism removal is killing rather than filtering. The MCV was successfully developed for the space shuttle to: disinfect fuel cell water; and prevent back contamination of the stored potable water supply. One version of the device consists of a high residual iodinated resin bed that imparts approximately 2 ppm of iodine to the fuel cell water as it flows to the potable water tanks. A second version of the device consists of a low residual iodinated resin bed. One of these low residual beds is located at each use port in the potable water system for the dual purpose of removing some iodine from the potable water as it is dispensed and also to prevent back contamination of the potable supply.

  20. Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report

    Directory of Open Access Journals (Sweden)

    Nikolic Aleksandra

    2012-09-01

    Full Text Available Abstract Introduction A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. Case presentation A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus