Cracks emerge due to various forces or stresses. After discerning the cracks preferably by non-destructive techniques, there is a need to find the reason for their appearance. With very exact analysis of the shape, form and dimension of the cracks and their location on the structural elements, we can deduce the reason for their formation.  This makes, proposing a suitable solution for preventin...

Cracks emerge due to various forces or stresses. After discerning the cracks preferably by non-destructive techniques, there is a need to find the reason for their appearance. With very exact analysis of the shape, form and dimension of the cracks and their location on the structural elements, we can deduce the reason for their formation. This makes, proposing a suitable solution for preventing...

Thirty ng/mm2 lumbrokinase, a potent fibrinolytic enzyme, was immobilized in a Korean type total artificial heart (KORTAH) valve by photoreaction; polyallylamine was used as a photoreactive linker. Lumbrokinase-immobilized polyurethane valves were then fitted to the total artificial hearts of 3 healthy 50 kg lambs. In the control lamb, the valves were untreated; in one other, only valves on the...

Calcific aortic stenosis is the most common valvular disease in the western world, with the prevalence increasing with age. Medical management of critical aortic stenosis is associated with high mortality and cost. While surgical valve replacement is ideal, high early morbidity and mortality limit its usefulness among patients with comorbid illness or advanced age. Balloon aortic valvuloplasty ...

The role of grain bridging in affecting the initial rising portion of the R-curve and the transient, non-steady-state behavior of short cracks during (cyclic) fatigue-crack propagation has been quantitatively examined in a 99.5% pure alumina. Fatigue-crack growth properties for both long and short ( af < 2 mm) cracks emanating from machined notches (root radius, 15–150 m) were investigated, whe...

 Appreciate the history of proportional control valves.  Explain the operation of proportional solenoids.  Describe various design considerations for proportional control valves.  Describe various proportional direction and proportional pressure control valves.  Explain the working of two-stage proportional valves.  Compare a proportional valve and a servo valve.  Describe the various ap...

Short whole circumference and semi-circumference intussusception valves were created in interposition cholecysto-jejunal-duodenal conduits in pigs to determine which method best prevented gastrointestinal reflux into the biliary tract. Following intravenous injection of 99 mTc-HIDA the time interval for its excretion from the liver and appearance in the duodenum was not different in either whol...

BACKGROUND For nearly a century, the mechanical failure of calcified heart valves was attributed to a passive degenerative process. Recently, several case reports described bone formation in surgically excised heart valves and suggested an unexpected process of tissue repair. METHODS AND RESULTS We studied the prevalence and pathology of heterotopic ossification in 347 surgically excised hear...

The fatigue growth of multiple cracks, of arbitrary lengths, emanating from a row of fastener holes in a bonded, riveted, lap joint in a pressurized aircraft fuselage is studied. The effects of residual stresses due to a rivet misfit, and of plastic deformation near the hole, are included. A Schwartz Neumann alternating method which uses the analytical solution for a row of multiple colinear cr...

The relationship between the crack nucleation and stress-induced martensitic transformation in the retained massive austenites (RM’s) of austempered ductile irons (ADIs) was examined in detail by carrying out tensile tests and scanning electron microscope (SEM) observations for an ADI material. The SEM observations revealed that cracks were not nucleated in the peripheral regions of graphite no...