Welin screw breech with mushroom-shaped de Bange obturator, and obturating ring behind Obturating rings are common in artillery, where the hard steel casing of the shell is too hard to practically deform to provide a tight seal for the propellant gases. An obturating ring or driving band made of a softer material is the typical solution. Mortar bombs also use obturating rings to provide a seal around the projectile. Recoilless rifles and some artillery use rings with a reverse impression of the rifling cut in them for a tighter seal even at very low pressures.
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Some artillery shells use an obturating ring at the rear of the shell to provide a tight seal for the breech. This allows a mostly caseless ammunition without the sealing issues generally encountered in such ammunition. The obturating ring provides the sealing that would normally be provided by a cartridge case.
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An obturating ring is a ring of relatively soft material designed to obturate under pressure to form a seal. Obturating rings are often found in artillery and other ballistics applications, and similar devices are also used in other applications such as plumbing, like the olive in a compression fitting. The term "O-ring" is sometimes used to describe this kind of pressure seal.
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Although there were early paper-cartridge breechloaders, the self-obturating nature of metallic cartridges (along with their waterproof nature) led to their rapid and almost universal adoption, in spite of their much greater cost.
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Obturating rings for the guns ran out, and the LAD had to improvise them from suet.Anon, History, pp. 161–2.Glover, pp. 77–9, 116.Farndale, Years of Defeat, pp. 152–3.Playfair, Vol I, pp. 433–4.
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Cannon breech with de Bange system. DeBange breech, function of the obturating ring Detail of the de Bange mechanism on a 155 mm de Bange siege cannon. De Bange obturator mechanism on the de Bange 90 mm field cannon. View of a de Bange 155 mm from the breech.
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Factory overbored barrels generally are made with a larger outside diameter, and will not have this reduction in weight—though the factory barrels will be tougher, since they have a normal barrel wall thickness. Firing slugs from overbored barrels can result in very inconsistent accuracy, as the slug may be incapable of obturating to fill the oversized bore.
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Clark-Holke et al. (2003) focused on determining the effect of the smear layer on the magnitude of bacterial penetration through the apical foramen around obturating materials. Thirty extracted teeth were classified into two test groups; the first group had the smear layer removed by rinsing with 17% EDTA while in the second group the smear layer was left intact. Canal preparation and obturation using lateral condensation, gutta-percha, and AH 26 sealer was performed on all of the teeth.
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Toxic ATN can be caused by free hemoglobin or myoglobin, by medication including antibiotics such as aminoglycoside, statins such as atorvastatin, and cytotoxic drugs such as cisplatin, or by intoxication (ethylene glycol, "anti-freeze"). Histopathology: Toxic ATN is characterized by proximal tubular epithelium necrosis (no nuclei, intense eosinophilic homogeneous cytoplasm, but preserved shape) due to a toxic substance (poisons, organic solvents, drugs, heavy metals). Necrotic cells fall into the tubule lumen, obturating it, and determining acute kidney failure. Basement membrane is intact, so the tubular epithelium regeneration is possible.
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Nickel titanium (NiTi) rotary file used in dentistry A nickel titanium (NiTi) rotary file is an engine-driven tapered and pointed endodontic instrument made of nickel titanium alloy with cutting edges used to mechanically shape and prepare the root canals during endodontic therapy or to remove the root canal obturating material while performing retreatment. The first NiTi file was introduced to the market in 1991. Superelasticity and shape memory are the properties that make Niti files very flexible. The high flexibility of Niti files makes them superior to stainless steel files for the purpose of rotary root canal preparation.
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BL 9.2 inch howitzer Mk II, showing position of obturating pad at far right The term BL, in its general sense, stood for breech loading, and contrasted with muzzle loading. The shell was loaded via the breech (i.e. the gunner's end of the barrel, which opened) followed by the propellant charge, and the breech mechanism was closed to seal the chamber. Breech loading, in its formal British ordnance sense, served to identify the gun as the type of rifled breechloading gun for which the powder charge was loaded in a silk or cloth bag and the breech mechanism was responsible for "obturation" i.e.
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The shell was loaded via the breech, followed by the propellant charge in a cloth bag. A single-use "vent sealing tube", a type of primer not dissimilar in appearance to a blank rifle round, was inserted into the breech for firing the gun. While originally, the term "BL" contrasted with "ML", or "muzzleloader" guns, after muzzleloaders were discontinued, the term came to distinguish between traditional, non-obturating guns with fabric propellant bags and separately loaded shells, and quick-firing QF guns which used self-sealing brass cartridge cases, and which usually had the propellant and projectile fixed together as a unit for faster handling and loading. For instance, Britain before World War I had both QF and BL 6 inch guns.
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