BACKGROUND Hydrodynamic performance of a decellularized pulmonary porcine valve was evaluated with a computer versatile pulse duplicator and compared to glutaraldehyde fixated stentless porcine bioprosthesis and a polyurethane heart valve. METHODS Decellularized pulmonary porcine matrices (Group I, n = 5) were treated chemically to become cell-free collagen matrices. The findings of this hear...

Capacity regulation system by controlling suction valve is useful for large scale reciprocating compressor in petrochemical engineering field. The dynamic performance of adjustment device influences the stability and accurancy of this system. In this paper, a mathematical model of adjustment device coupled with the motion of suction valve is built, and the dynamic performances of valve plate ar...

For a mechanical heart valve, a strong spike in pressure during closing is associated with valve wear and erythrocyte damage; thus, for valid in vitro testing, the mock circulation system should replicate the conditions, including pressure spikes, expected in vivo. To address this issue, a study was performed to investigate how mock circulation input impedance affects valve closure dynamics. A ...

Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal...

Engines equipped with camless valve trains will have greater space for performance optimization. In this paper, based on the electromagnetic actuated valve train system, one-dimensional and three-dimensional simulation models on engine thermodynamic cycle and in-cylinder charge motion are established, respectively. With the application of early-intake-valve closing (EIVC) strategy，unthrottled l...

BACKGROUND Cardiac resynchronization therapy (CRT) has been shown to reduce functional mitral regurgitation (MR). It has been proposed that the mechanism of MR reduction relates to geometric change or, alternatively, changes in left ventricular (LV) contractile function. Normal mitral valve (MV) function relies on a balance between tethering and closing forces on the MV leaflets. Functional MR ...

BACKGROUND The durability of aortic valve-sparing procedures is negatively affected by increased leaflet stress in the absence of normally shaped sinuses of Valsalva. We compared valve motion after remodeling procedures using a standard conduit and a specifically designed aortic root conduit. METHODS Echocardiographic studies of the aortic valve dynamics were performed in 14 patients after re...

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 ...

Introduction The opening and closing behavior of the valve is a delicate interaction between blood flow and geometrical and stiffness properties of the heart valve leaflets and aortic root. Numerical analysis of the opening and closing behavior is complicated by the three-dimensional finite motion of the very flexible leaflets in a compliant system of fluid and structure. Fluid-structure intera...

OBJECTIVES Real-time monitoring of the aortic valve function and the loading state of the left ventricle (LV) during mechanical circulatory support is essential. Therefore, we developed a system that determines accurately the aortic valve closing moment based on integrals derived from the pump inlet pressure and the pump power [pressure-power area (PPA)]. METHODS A Deltastream diagonal pump w...