What's the difference between piston and valve?

Piston


Definition:

  • (n.) A sliding piece which either is moved by, or moves against, fluid pressure. It usually consists of a short cylinder fitting within a cylindrical vessel along which it moves, back and forth. It is used in steam engines to receive motion from the steam, and in pumps to transmit motion to a fluid; also for other purposes.

Example Sentences:

  • (1) The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage.
  • (2) Both groups were ventilated with a constant-volume piston ventilator.
  • (3) To give variations in the peak flow-rate (from pulsatile to intermediate to non-pulsatile), three types of blood pump (piston-bellows, screw, and centrifugal) were applied to dogs.
  • (4) The players were each to be given a present: Dietmar Hamann (he's German, tee hee hee) got a copy of Mein Kampf, while the Italian Alessandro Pistone, perceived as lacking fight, was given a sheep's heart.
  • (5) After 4 minutes of ventricular fibrillation CPR was performed with the use of a pneumatic piston compressor.
  • (6) Sinusoidal volume changes were delivered through a tracheostomy by a piston pump driven by a linear motor.
  • (7) In groups I-III it is possible to discover whether the piston is too long or too short, whether it is dislocated or has slipped.
  • (8) Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump.
  • (9) The vein graft technique (nine cases) is very much inferior to the piston technique.
  • (10) Results of partial stapedectomy with the formation of small fenestra and the use of teflon piston prostheses in the period of 1980-1984 are shown.
  • (11) They suck, by means of a stylet acting as a piston, all components of the muscle cell which develops into a nurse cell, into their oral cavity.
  • (12) A pneumatically driven piston was used to cause a mechanical stress (10-150 N) on the stabilized tooth crown for 30 s, with instantaneous onset and release.
  • (13) They recorded an auditory gain in more than half the patients (early: PORP 97%, TORP 73%, piston 52%; plasty transplants of ossicles obtained from subjects who died accidentallyÄ• For preserfic Council of the Ministry of Health, Czech Socialist Republic, recommended, based on the clinical tests, the manufacture of silastic prostheses of the middle ear.
  • (14) It is designed as a positive displacement pump, with blood allowed to collect in a valved cavity from which it is ejected by the reciprocating action of a piston.
  • (15) The ejection force is wholly produced by the compressed coil spring and is transmitted to the piston in the blood chamber by a rod.
  • (16) The 4 modes of failure characterizing stem-type component progressive loosening mechanisms consisted of stem pistoning within the acrylic (3.3%), cement-embedded stem pistoning with the femur (5.1%), medial midstem pivot (2.5%), calcar pivot (0.7%) and bending (fatigue) cantilever (3.3%).
  • (17) In model 1, diaphragmatic descent was treated as if it were a "piston in a cylinder."
  • (18) Insertion, which takes only a few minutes, is accomplished with a plastic tube and piston device.
  • (19) The expanding ameroid pushes a piston with a concave extension (makrolon) a maximum of 2 mm against the artery, which is fixed to the metal housing by a teflon band (width: 4 mm, thickness: 0.5 mm).
  • (20) The novel design of this pump incorporates two rack-mounted pistons, driven into opposing cylinders by a micro-stepping motor.

Valve


Definition:

  • (n.) A door; especially, one of a pair of folding doors, or one of the leaves of such a door.
  • (n.) A lid, plug, or cover, applied to an aperture so that by its movement, as by swinging, lifting and falling, sliding, turning, or the like, it will open or close the aperture to permit or prevent passage, as of a fluid.
  • (n.) One or more membranous partitions, flaps, or folds, which permit the passage of the contents of a vessel or cavity in one direction, but stop or retard the flow in the opposite direction; as, the ileocolic, mitral, and semilunar valves.
  • (n.) One of the pieces into which a capsule naturally separates when it bursts.
  • (n.) One of the two similar portions of the shell of a diatom.
  • (n.) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, as in the barberry.
  • (n.) One of the pieces or divisions of bivalve or multivalve shells.

Example Sentences:

  • (1) This paper discusses the typical echocardiographic patterns of a variety of important conditions concerning the mitral valve, the left ventricle, the interatrial and interventricular septum as well as the influence of respiration on the performance of echocardiograms.
  • (2) External phonocardiography performed at the time of cardiac catheterization revealed that this loud midsystolic click disappeared whenever a catheter was positioned across the mitral valve.
  • (3) All patients with localized subaortic hypertrophy had left ventricular hypertrophy (left ventricular mass or posterior wall thickness greater than 2 SD from normal) with a normal size cavity due to aortic valve disease (2 patients were also hypertensive).
  • (4) Valve-related complications were noted in four patients.
  • (5) Digestion is initiated in the gastric region by secretion of acid and pepsin; however, diversity of digestive enzymes is highest in the post-gastric alimentary canal with the greatest proteolytic activity in the spiral valve.
  • (6) The aortic area (Torlin) for diseased stenotic aortic valves was calculated in 10 patients using two different methods; data obtained in preoperative cardiac catheterization and by intraoperative flowmetric and aortic and left ventricular pressure-recording measurements, and their mutual correlation was tested.
  • (7) He underwent a mitral and aortic valve replacement, followed by a complicated postoperative course.
  • (8) In addition, spontaneous platelet aggregation is increased when vegetations are present on cardiac valves.
  • (9) This report represents the first comprehensive description of instantaneous and continous phasic blood velocity at the mitral valve during atrial arrhythmias in man.
  • (10) This study demonstrated that significant global and regional ventricular dysfunction develops immediately after removal of the papillary muscles, whereas myocardial contractility is preserved in patients undergoing mitral valve repair.
  • (11) The autopsy findings in 41 patients with University of Cape Town aortic valve prostheses were studied.
  • (12) This developed concept of "valve only" energy loss has the potential of standardising the findings of different research groups by removing the arbitrary selection of measurement points from reported results.
  • (13) The organisms were predominantly associated with host deposits of erythrocytes, phagocytes, platelets, and fibrinous-appearing material, which collectively appeared on the valve surface in response to trauma.
  • (14) Autopsy revealed a primary intimal sarcoma with osteogenic elements arising in the posterior leaflet of the pulmonary valve and obstructing the main pulmonary artery and its right branch.
  • (15) With a series of 117 aortic valve replacements, the authors have examined the results in relation to the method of protecting the myocardium while the aorta is clamped off.
  • (16) Left ventricular rupture is a serious complication of mitral valve replacement.
  • (17) Any type of valve element can serve as the expiratory valve.
  • (18) Echocardiographic findings included an abrupt midsystolic, posterior motion (greater than 3 mm beyond the CD line) in five patients, multiple sequence echoes in six, and posterior coaptation of the mitral valve near the left atrial wall in six.
  • (19) A block of tissue bounded by the ostium of the coronary sinus, the pars membranacea, the septal leaflet of the tricuspid valve and the atrial and ventricular septa is removed.
  • (20) A case of tricuspid valve endocarditis with spinal epidural abscess caused by Actinobacillus actinomycetemcomitans is reported in a 74-year-old male with an endocardial pacemaker.