Alloys: A mixture of metallic elements or compounds with other metallic or metalloid elements in varying proportions.Gold Alloys: Alloys that contain a high percentage of gold. They are used in restorative or prosthetic dentistry.Chromium Alloys: Specific alloys not less than 85% chromium and nickel or cobalt, with traces of either nickel or cobalt, molybdenum, and other substances. They are used in partial dentures, orthopedic implants, etc.Metal Ceramic Alloys: The fusion of ceramics (porcelain) to an alloy of two or more metals for use in restorative and prosthodontic dentistry. Examples of metal alloys employed include cobalt-chromium, gold-palladium, gold-platinum-palladium, and nickel-based alloys.Titanium: A dark-gray, metallic element of widespread distribution but occurring in small amounts; atomic number, 22; atomic weight, 47.90; symbol, Ti; specific gravity, 4.5; used for fixation of fractures. (Dorland, 28th ed)Dental Casting Technique: The process of producing a form or impression made of metal or plaster using a mold.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Dental Casting Investment: Material from which the casting mold is made in the fabrication of gold or cobalt-chromium castings. (Boucher's Clinical Dental Terminology, 4th ed, p168)Palladium: A chemical element having an atomic weight of 106.4, atomic number of 46, and the symbol Pd. It is a white, ductile metal resembling platinum, and following it in abundance and importance of applications. It is used in dentistry in the form of gold, silver, and copper alloys.Silver: Silver. An element with the atomic symbol Ag, atomic number 47, and atomic weight 107.87. It is a soft metal that is used medically in surgical instruments, dental prostheses, and alloys. Long-continued use of silver salts can lead to a form of poisoning known as ARGYRIA.Tin: A trace element that is required in bone formation. It has the atomic symbol Sn, atomic number 50, and atomic weight 118.71.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Differential Thermal Analysis: Technique by which phase transitions of chemical reactions can be followed by observation of the heat absorbed or liberated.Electron Probe Microanalysis: Identification and measurement of ELEMENTS and their location based on the fact that X-RAYS emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration. It is performed with an electron microscope fitted with an x-ray spectrometer, in scanning or transmission mode.Aluminum Oxide: An oxide of aluminum, occurring in nature as various minerals such as bauxite, corundum, etc. It is used as an adsorbent, desiccating agent, and catalyst, and in the manufacture of dental cements and refractories.Dental Polishing: Creation of a smooth and glossy surface finish on a denture or amalgam.Methylmethacrylates: The methyl esters of methacrylic acid that polymerize easily and are used as tissue cements, dental materials, and absorbent for biological substances.Nickel: A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.Hardness: The mechanical property of material that determines its resistance to force. HARDNESS TESTS measure this property.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Dental Bonding: An adhesion procedure for orthodontic attachments, such as plastic DENTAL CROWNS. This process usually includes the application of an adhesive material (DENTAL CEMENTS) and letting it harden in-place by light or chemical curing.Gallium: A rare, metallic element designated by the symbol, Ga, atomic number 31, and atomic weight 69.72.Niobium: Niobium. A metal element atomic number 41, atomic weight 92.906, symbol Nb. (From Dorland, 28th ed)Methacrylates: Acrylic acids or acrylates which are substituted in the C-2 position with a methyl group.Stainless Steel: Stainless steel. A steel containing Ni, Cr, or both. It does not tarnish on exposure and is used in corrosive environments. (Grant & Hack's Chemical Dictionary, 5th ed)Dental Etching: Preparation of TOOTH surfaces, and of materials bonded to teeth or DENTAL IMPLANTS, with agents and methods which roughen the surface to facilitate adhesion. Agents include phosphoric or other acids (ACID ETCHING, DENTAL) and methods include LASERS.Electroplating: Coating with a metal or alloy by electrolysis.Thiouracil: Occurs in seeds of Brassica and Crucifera species. Thiouracil has been used as antithyroid, coronary vasodilator, and in congestive heart failure although its use has been largely supplanted by other drugs. It is known to cause blood dyscrasias and suspected of terato- and carcinogenesis.Tensile Strength: The maximum stress a material subjected to a stretching load can withstand without tearing. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p2001)Indium: A metallic element, atomic number 49, atomic weight 114.82, symbol In. It is named from its blue line in the spectrum. (From Dorland, 28th ed)Shear Strength: The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.Platinum: Platinum. A heavy, soft, whitish metal, resembling tin, atomic number 78, atomic weight 195.09, symbol Pt. (From Dorland, 28th ed) It is used in manufacturing equipment for laboratory and industrial use. It occurs as a black powder (platinum black) and as a spongy substance (spongy platinum) and may have been known in Pliny's time as "alutiae".Photoelectron Spectroscopy: The study of the energy of electrons ejected from matter by the photoelectric effect, i.e., as a direct result of absorption of energy from electromagnetic radiation. As the energies of the electrons are characteristic of a specific element, the measurement of the energy of these electrons is a technique used to determine the chemical composition of surfaces.Resin Cements: Dental cements composed either of polymethyl methacrylate or dimethacrylate, produced by mixing an acrylic monomer liquid with acrylic polymers and mineral fillers. The cement is insoluble in water and is thus resistant to fluids in the mouth, but is also irritating to the dental pulp. It is used chiefly as a luting agent for fabricated and temporary restorations. (Jablonski's Dictionary of Dentistry, 1992, p159)Metallurgy: The science, art, or technology dealing with processes involved in the separation of metals from their ores, the technique of making or compounding the alloys, the techniques of working or heat-treating metals, and the mining of metals. It includes industrial metallurgy as well as metallurgical techniques employed in the preparation and working of metals used in dentistry, with special reference to orthodontic and prosthodontic appliances. (From Jablonski, Dictionary of Dentistry, 1992, p494)Carbon Compounds, Inorganic: Inorganic compounds that contain carbon as an integral part of the molecule but are not derived from hydrocarbons.Dental Prosthesis Retention: Holding a DENTAL PROSTHESIS in place by its design, or by the use of additional devices or adhesives.Dental Materials: Materials used in the production of dental bases, restorations, impressions, prostheses, etc.Dental Porcelain: A type of porcelain used in dental restorations, either jacket crowns or inlays, artificial teeth, or metal-ceramic crowns. It is essentially a mixture of particles of feldspar and quartz, the feldspar melting first and providing a glass matrix for the quartz. Dental porcelain is produced by mixing ceramic powder (a mixture of quartz, kaolin, pigments, opacifiers, a suitable flux, and other substances) with distilled water. (From Jablonski's Dictionary of Dentistry, 1992)Orthodontic Wires: Wires of various dimensions and grades made of stainless steel or precious metal. They are used in orthodontic treatment.Silicon Compounds: Inorganic compounds that contain silicon as an integral part of the molecule.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.ThionesBoron Compounds: Inorganic or organic compounds that contain boron as an integral part of the molecule.Silanes: Compounds similar to hydrocarbons in which a tetravalent silicon atom replaces the carbon atom. They are very reactive, ignite in air, and form useful derivatives.Dental Cements: Substances used to bond COMPOSITE RESINS to DENTAL ENAMEL and DENTIN. These bonding or luting agents are used in restorative dentistry, ROOT CANAL THERAPY; PROSTHODONTICS; and ORTHODONTICS.Chromium: A trace element that plays a role in glucose metabolism. It has the atomic symbol Cr, atomic number 24, and atomic weight 52. According to the Fourth Annual Report on Carcinogens (NTP85-002,1985), chromium and some of its compounds have been listed as known carcinogens.Dental Clasps: Metal devices for fastening together two or more parts of dental prostheses for stabilizing or retaining them by attachment to abutment teeth. For a precision attachment for a partial denture DENTURE PRECISION ATTACHMENT is available.Acrylic ResinsCrowns: A prosthetic restoration that reproduces the entire surface anatomy of the visible natural crown of a tooth. It may be partial (covering three or more surfaces of a tooth) or complete (covering all surfaces). It is made of gold or other metal, porcelain, or resin.Dental Prosthesis Design: The plan and delineation of dental prostheses in general or a specific dental prosthesis. It does not include DENTURE DESIGN. The framework usually consists of metal.Dental Amalgam: An alloy used in restorative dentistry that contains mercury, silver, tin, copper, and possibly zinc.Hardness Tests: A test to determine the relative hardness of a metal, mineral, or other material according to one of several scales, such as Brinell, Mohs, Rockwell, Vickers, or Shore. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Aluminum: A metallic element that has the atomic number 13, atomic symbol Al, and atomic weight 26.98.Copper: A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.Denture, Partial, Removable: A partial denture designed and constructed to be removed readily from the mouth.Spectrometry, X-Ray Emission: The spectrometric analysis of fluorescent X-RAYS, i.e. X-rays emitted after bombarding matter with high energy particles such as PROTONS; ELECTRONS; or higher energy X-rays. Identification of ELEMENTS by this technique is based on the specific type of X-rays that are emitted which are characteristic of the specific elements in the material being analyzed. The characteristic X-rays are distinguished and/or quantified by either wavelength dispersive or energy dispersive methods.Cobalt: A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.Prostheses and Implants: Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.Dielectric Spectroscopy: A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.Sulfur Compounds: Inorganic or organic compounds that contain sulfur as an integral part of the molecule.Zirconium: Zirconium. A rather rare metallic element, atomic number 40, atomic weight 91.22, symbol Zr. (From Dorland, 28th ed)Methylmethacrylate: The methyl ester of methacrylic acid. It polymerizes easily to form POLYMETHYL METHACRYLATE. It is used as a bone cement.Dental Veneers: The use of a layer of tooth-colored material, usually porcelain or acrylic resin, applied to the surface of natural teeth, crowns, or pontics by fusion, cementation, or mechanical retention.Air Abrasion, Dental: A technique using a pneumatic, high-pressure stream of aluminum oxide to remove DENTAL ENAMEL; DENTIN; and restorative materials from teeth. In contrast to using DENTAL HIGH-SPEED EQUIPMENT, this method usually requires no dental anesthesia (ANESTHESIA, DENTAL) and reduces risks of tooth chipping and microfracturing. It is used primarily for routine DENTAL CAVITY PREPARATION.Potentiometry: Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Pliability: The quality or state of being able to be bent or creased repeatedly. (From Webster, 3d ed)Dental Abutments: Natural teeth or teeth roots used as anchorage for a fixed or removable denture or other prosthesis (such as an implant) serving the same purpose.Immersion: The placing of a body or a part thereof into a liquid.Coated Materials, Biocompatible: Biocompatible materials usually used in dental and bone implants that enhance biologic fixation, thereby increasing the bond strength between the coated material and bone, and minimize possible biological effects that may result from the implant itself.Magnesium Oxide: Magnesium oxide (MgO). An inorganic compound that occurs in nature as the mineral periclase. In aqueous media combines quickly with water to form magnesium hydroxide. It is used as an antacid and mild laxative and has many nonmedicinal uses.Adhesiveness: A property of the surface of an object that makes it stick to another surface.Composite Resins: Synthetic resins, containing an inert filler, that are widely used in dentistry.Electrolysis: Destruction by passage of a galvanic electric current, as in disintegration of a chemical compound in solution.Ceramics: Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed)Oxides: Binary compounds of oxygen containing the anion O(2-). The anion combines with metals to form alkaline oxides and non-metals to form acidic oxides.Potassium Compounds: Inorganic compounds that contain potassium as an integral part of the molecule.Mechanical Phenomena: The properties and processes of materials that affect their behavior under force.Biocompatible Materials: Synthetic or natural materials, other than DRUGS, that are used to replace or repair any body TISSUES or bodily function.Osseointegration: The growth action of bone tissue as it assimilates surgically implanted devices or prostheses to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants).Denture Repair: The process of reuniting or replacing broken or worn parts of a denture.Mechanics: The branch of physics which deals with the motions of material bodies, including kinematics, dynamics, and statics. When the laws of mechanics are applied to living structures, as to the locomotor system, it is referred to as BIOMECHANICAL PHENOMENA. (From Dorland, 28th ed)Dental Implants: Biocompatible materials placed into (endosseous) or onto (subperiosteal) the jawbone to support a crown, bridge, or artificial tooth, or to stabilize a diseased tooth.Metals: Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)Dental Disinfectants: Chemicals especially for use on instruments to destroy pathogenic organisms. (Boucher, Clinical Dental Terminology, 4th ed)Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Elasticity: Resistance and recovery from distortion of shape.Polarography: An electrochemical technique for measuring the current that flows in solution as a function of an applied voltage. The observed polarographic wave, resulting from the electrochemical response, depends on the way voltage is applied (linear sweep or differential pulse) and the type of electrode used. Usually a mercury drop electrode is used.Denture Design: The plan, delineation, and location of actual structural elements of dentures. The design can relate to retainers, stress-breakers, occlusal rests, flanges, framework, lingual or palatal bars, reciprocal arms, etc.Calcium Sulfate: A calcium salt that is used for a variety of purposes including: building materials, as a desiccant, in dentistry as an impression material, cast, or die, and in medicine for immobilizing casts and as a tablet excipient. It exists in various forms and states of hydration. Plaster of Paris is a mixture of powdered and heat-treated gypsum.Cariostatic Agents: Substances that inhibit or arrest DENTAL CARIES formation. (Boucher's Clinical Dental Terminology, 4th ed)Electrochemical Techniques: The utilization of an electrical current to measure, analyze, or alter chemicals or chemical reactions in solution, cells, or tissues.Color: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Electrogalvanism, Intraoral: Chemical reaction that occurs when saliva comes into contact with the metals in dental fillings. This reaction can send electric currents through the brain causing negative symptoms.Friction: Surface resistance to the relative motion of one body against the rubbing, sliding, rolling, or flowing of another with which it is in contact.Plasma Gases: Ionized gases, consisting of free electrons and ionized atoms or molecules which collectively behave differently than gas, solid, or liquid. Plasma gases are used in biomedical fields in surface modification; biological decontamination; dentistry (e.g., PLASMA ARC DENTAL CURING LIGHTS); and in other treatments (e.g., ARGON PLASMA COAGULATION).Denture, Overlay: Removable prosthesis constructed over natural teeth or implanted studs.X-Ray Diffraction: The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Tooth Preparation, Prosthodontic: The selected form given to a natural tooth when it is reduced by instrumentation to receive a prosthesis (e.g., artificial crown or a retainer for a fixed or removable prosthesis). The selection of the form is guided by clinical circumstances and physical properties of the materials that make up the prosthesis. (Boucher's Clinical Dental Terminology, 4th ed, p239)Hot Temperature: Presence of warmth or heat or a temperature notably higher than an accustomed norm.Dental Prosthesis, Implant-Supported: A prosthesis that gains its support, stability, and retention from a substructure that is implanted under the soft tissues of the basal seat of the device and is in contact with bone. (From Boucher's Clinical Dental Terminology, 4th ed)Dental Restoration, Permanent: A restoration designed to remain in service for not less than 20 to 30 years, usually made of gold casting, cohesive gold, or amalgam. (Jablonski, Dictionary of Dentistry, 1992)Diamond: Diamond. A crystalline form of carbon that occurs as hard, colorless or tinted isomeric crystals. It is used as a precious stone, for cutting glass, and as bearings for delicate mechanisms. (From Grant & Hackh's Chemical Dictionary, 5th ed)Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Photomicrography: Photography of objects viewed under a microscope using ordinary photographic methods.Absorbable Implants: Implants constructed of materials designed to be absorbed by the body without producing an immune response. They are usually composed of plastics and are frequently used in orthopedics and orthodontics.Silicon Dioxide: Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, QUARTZ, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid.Hip Prosthesis: Replacement for a hip joint.Polymethyl Methacrylate: Polymerized methyl methacrylate monomers which are used as sheets, moulding, extrusion powders, surface coating resins, emulsion polymers, fibers, inks, and films (From International Labor Organization, 1983). This material is also used in tooth implants, bone cements, and hard corneal contact lenses.Yttrium: An element of the rare earth family of metals. It has the atomic symbol Y, atomic number 39, and atomic weight 88.91. In conjunction with other rare earths, yttrium is used as a phosphor in television receivers and is a component of the yttrium-aluminum garnet (YAG) lasers.Computer-Aided Design: The use of computers for designing and/or manufacturing of anything, including drugs, surgical procedures, orthotics, and prosthetics.Gold: A yellow metallic element with the atomic symbol Au, atomic number 79, and atomic weight 197. It is used in jewelry, goldplating of other metals, as currency, and in dental restoration. Many of its clinical applications, such as ANTIRHEUMATIC AGENTS, are in the form of its salts.Inlays: Restorations of metal, porcelain, or plastic made to fit a cavity preparation, then cemented into the tooth. Onlays are restorations which fit into cavity preparations and overlay the occlusal surface of a tooth or teeth. Onlays are retained by frictional or mechanical factors.Molybdenum: A metallic element with the atomic symbol Mo, atomic number 42, and atomic weight 95.94. It is an essential trace element, being a component of the enzymes xanthine oxidase, aldehyde oxidase, and nitrate reductase. (From Dorland, 27th ed)Prosthesis Coloring: Coloring, shading, or tinting of prosthetic components, devices, and materials.WeldingBeryllium: Beryllium. An element with the atomic symbol Be, atomic number 4, and atomic weight 9.01218. Short exposure to this element can lead to a type of poisoning known as BERYLLIOSIS.Implants, Experimental: Artificial substitutes for body parts and materials inserted into organisms during experimental studies.Chromium Compounds: Inorganic compounds that contain chromium as an integral part of the molecule.Tungsten: Tungsten. A metallic element with the atomic symbol W, atomic number 74, and atomic weight 183.85. It is used in many manufacturing applications, including increasing the hardness, toughness, and tensile strength of steel; manufacture of filaments for incandescent light bulbs; and in contact points for automotive and electrical apparatus.Argon: Argon. A noble gas with the atomic symbol Ar, atomic number 18, and atomic weight 39.948. It is used in fluorescent tubes and wherever an inert atmosphere is desired and nitrogen cannot be used.Porosity: Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.Phosphonoacetic Acid: A simple organophosphorus compound that inhibits DNA polymerase, especially in viruses and is used as an antiviral agent.Mercury Compounds: Inorganic compounds that contain mercury as an integral part of the molecule.Spectrophotometry, Atomic: Spectrophotometric techniques by which the absorption or emmision spectra of radiation from atoms are produced and analyzed.Polymethacrylic Acids: Poly-2-methylpropenoic acids. Used in the manufacture of methacrylate resins and plastics in the form of pellets and granules, as absorbent for biological materials and as filters; also as biological membranes and as hydrogens. Synonyms: methylacrylate polymer; poly(methylacrylate); acrylic acid methyl ester polymer.Equipment Reuse: Further or repeated use of equipment, instruments, devices, or materials. It includes additional use regardless of the original intent of the producer as to disposability or durability. It does not include the repeated use of fluids or solutions.

Transcatheter closure of secundum atrial septal defects with the new self-centering Amplatzer Septal Occluder. (1/452)

AIMS: The study was set up to find out whether a new self-centering prosthesis for transcatheter closure of secundum atrial septal defects could overcome the disadvantages of previously described devices. METHODS AND RESULTS: Fifty-two consecutive patients with a significant atrial septal defect were considered for transcatheter closure with the Amplatzer Septal Occluder. The device, made of a Nitinol and polyester fabric mesh, provides a different approach to defect occlusion by stenting the atrial septal defect up to a stretched diameter of 26 mm. Three infants whose large defects were demonstrated on a transthoracic echocardiogram were excluded from transcatheter treatment. On transoesophageal echocardiography, 49 defects ranged from 6-26 mm, in one adult the defect measured 28 mm and this patient was excluded from attempted transcatheter closure. At cardiac catheterization in five further patients, devices were not implanted, in two because the stretched diameter exceeded 26 mm and in three the device was withdrawn because it was unstable or compromised the mitral valve. Thus, device closure was performed in 43 patients. At follow-up after 3 months the complete closure rate was 97%. CONCLUSION: The self-centering Amplatzer Septal Occluder is very efficient and user-friendly and offers interventional closure in 83% of an unselected group of patients presented with an atrial septal defect.  (+info)

New device for closure of muscular ventricular septal defects in a canine model. (2/452)

BACKGROUND: Repair of muscular ventricular septal defects (MVSDs) has always been challenging to the surgeon. Long-term morbidity and mortality are significantly increased if the defects are closed via left ventriculotomy or if they are associated with other complex congenital anomalies. The purpose of this study was to close MVSDs with the Amplatz ventricular septal defect device. This device is constructed from 0.004-in nitinol wire mesh filled with polyester fibers. It is retrievable, repositionable, self-centering, and of low profile. METHODS AND RESULTS: MVSDs were created with the help of a sharp punch in 10 dogs. The location of the defects was anterior muscular (n=3), midmuscular (n=3), apical (n=3), and inlet muscular (n=1). The diameter of the defects ranged from 6 to 14 mm. All defects were closed in the catheterization laboratory. The device was placed with the help of transesophageal echocardiography and fluoroscopy. A 7F sheath was used to deploy the device from the right ventricular side in 8 and the left ventricular side in 2 dogs. Placement was successful in all animals. The complete closure rate was 30% (3/10) immediately after placement and 100% at 1-week follow-up. Pathological examination of the heart revealed complete endothelialization of the device in dogs killed after 3 months. CONCLUSIONS: The Amplatz ventricular septal defect device appears highly efficacious in closing MVSDs. The advantages include a small delivery sheath, complete retrievability before release, and the fact that it is self-centering and self-expanding, thereby making it an attractive option in smaller children.  (+info)

Origin of graphitic carbon and pentlandite in matrix olivines in the Allende meteorite. (3/452)

Matrix olivines in the Allende carbonaceous chondrite are believed to have formed by condensation processes in the primitive solar nebula. However, transmission electron microscope observations of numerous matrix olivines show that they contain abundant, previously unrecognized, nanometer-sized inclusions of pentlandite and poorly graphitized carbon. Neither of these phases would have been stable at the high-temperature conditions required to condense iron-rich olivine in the solar nebula. The presence of these inclusions is consistent with formation of the olivines by parent body processes that involved overgrowth of fine-grained organic materials and sulfides in the precursor matrix materials.  (+info)

Further experience with transcatheter closure of the patent ductus arteriosus using the Amplatzer duct occluder. (4/452)

OBJECTIVE: The aim of this study was to report further experience with transcatheter closure of the patent ductus arteriosus (PDA) using the Amplatzer duct occluder (ADO). BACKGROUND: The design of previously used devices is not ideal for this purpose, and their use has been associated with several drawbacks, especially in large PDAs. METHODS: Forty-three patients, aged 0.3 to 33 years (mean 6.4+/-6.7 years), with a moderate to large, type A to E PDA, underwent attempted transcatheter closure using the ADO. The device is a plug-shaped repositionable occluder made of 0.004-in. nitinol wire mesh. It is delivered through a 5F to 6F long sheath. The mean PDA diameter (at the pulmonary end) was 3.9+/-1.2 mm (range 2.2 to 8 mm). All patients had color flow echocardiographic follow-up (6 to 24 months) at 24 h, 1 and 3 months after closure, and at 6-month intervals thereafter. RESULTS: The mean ADO diameter was 6.1+/-1.4 mm (range 4 to 10 mm). Complete angiographic closure was seen in 40 of 43 patients (93%; 95% confidence interval [CI] 85.4% to 100%). The remaining three patients had a trivial angiographic shunt through the ADO. At 24 h, color flow mapping revealed no shunt in all patients. A 9F long sheath was required for repositioning of a misplaced 8-mm device into the pulmonary artery. The mean fluoroscopy time was 7.9+/-1.6 min (range 4.6 to 12 min). There were no complications. No obstruction of the descending aorta or the pulmonary artery branches was noted on Doppler follow-up studies. Neither thromboembolization nor hemolysis or device failure was encountered. CONCLUSIONS: Transcatheter closure using the ADO is an effective and safe therapy for the majority of patients with patency of the arterial duct. Further studies are required to establish long-term results in a larger patient population.  (+info)

Successful percutaneous endovascular treatment of a ruptured popliteal artery aneurysm. (5/452)

A rupture of the popliteal artery is a rare but dangerous complication of aneurysmal disease. It accounts for 4% of all popliteal artery aneurysms encountered and threatens the loss of the extremity and, infrequently, is also life-threatening.(1) when this clinical entity is confronted, a prompt operative intervention is indispensable for increasing the chances of limb salvage. We report the first, to our knowledge, successful endovascular treatment of a ruptured popliteal artery aneurysm with a new polytetrafluoroethylene stent-graft in a patient who was unfit for a conventional surgical approach because of his severe pulmonary disease.  (+info)

Hard metal alveolitis accompanied by rheumatoid arthritis. (6/452)

Hard metal lung diseases (HML) are rare, and complex to diagnose. We describe the case of a patient with allergic alveolitis accompanied by rheumatoid arthritis. A sharpener of hard metal by trade, our patient was a 45-year-old, nonsmoking Caucasian female who experienced symptoms of cough and phlegm, and dyspnea on exertion. Preliminary lung findings were inspiratory rales in both basal areas, decreased diffusion capacity and a radiological picture resembling sarcoidosis. A high-resolution computed tomography scan indicated patchy alveolitis as well. An open lung biopsy revealed non-necrotizing granulomas consisting of epitheloid cells and surrounded by lymphocytes, plasma cells and a few eosinophils. These cells also occupied the thickened alveolar interstitium. Macrophages in the alveolar spaces, some of them multinuclear, contained dust particles. Hard metal alveolitis is clinically well known and, in this patient, has been described histologically. After the patient had quit working with hard metal and following corticosteroid therapy, pulmonary symptoms and signs were relieved. During this recovery period, however, she contracted rheumatoid arthritis.  (+info)

Endovascular stenting for carotid artery stenosis: preliminary experience using the shape-memory- alloy-recoverable-technology (SMART) stent. (7/452)

We describe our initial clinical experience using the newly available self-expanding, Nitinol, shape-memory-, alloy-recoverable-technology (SMART) stent in treating carotid artery occlusive disease. Five stents were used in four carotid arteries in four consecutive patients with carotid stenosis of at least 70%. Technical success (<20% residual stenosis) was achieved in all cases. No procedural complications specifically related to use of the SMART stent were encountered. All patients remained symptom-free, with no evidence of transient ischemic attacks or new strokes during an average follow-up period of 6 months. Excellent performance of the SMART stent for the endovascular treatment of carotid artery stenosis has been shown based on our early experience. Validation with greater numbers and longer-term follow-up is required. The specific technical characteristics, potential advantages, and disadvantages of this stent are discussed and compared with other currently used carotid artery stents.  (+info)

Nitinol - its use in vascular surgery and other applications. (8/452)

OBJECTIVES: to describe the physical properties of shape-memory alloys and the surgical, scientific and commercial applications of nitinol, in particular. DESIGN AND METHODS: a Medline, Internet and library search with contributions from commerce to describe the alloy's structure, behaviour and biocompatibility, and design for devices constructed from nitinol. RESULTS: nitinol has the properties of thermal shape memory and superelasticity that make it ideal for many vascular and general surgical prostheses and disposables, and for various commercial applications. CONCLUSIONS: further research into shape-memory alloys from scientific and commercial groups should widen their use in vascular and endovascular surgery.  (+info)

  • 2. Babak A., Casi E.N., Barsoum M.W. (2014), Fabrication and mechanical properties of pressureless melt infiltrated magnesium alloy composites reinforced with TiC and Ti 2 AlC particles, Materials Science and Engineering , 618, 511-522. (
  • Apple further points out that the actuation members described may be formed at least partially from one or more shape-memory alloy (SMA) materials that change shape (e.g., expands or contracts) in response to an applied electrical current. (
  • According to Bucsek, the gap between the development of a shape memory alloy and its implementation is similar to the problem encountered by scientists with other advanced materials. (
  • The Automotive Alloys market in the U.S. is estimated at US$40.2 Billion in the year 2020. (
  • All new butted 6061 alloy triple triangle frame design featuring floating seat stays, internal cable routing, Stealth dropper post routing, forged drop outs for thru-axle w chainstay mounted disc brake, Boost 148mm rear spacing, tapered 1 1/8"- 1 ½" head tube. (
  • Padmanabh Alloys & Polymers Board Meeting Intimation for Considering Un-Audited Financial Results For Half Year Ended On 30/09/2019. (
  • PADMANABH ALLOYS & POLYMERS LTD.has informed BSE that the meeting of the Board of Directors of the Company is scheduled on 14/11/2019 ,inter alia, to consider and approve un-audited financial results for half year ended on 30/09/2019. (
  • Padmanabh Alloys & Polymers Intimation Of Annual General Meeting To Be Held On 30Th September, 2019. (
  • Padmanabh Alloys & Polymers Board Meeting Intimation for Considering And Approving Un-Audited Financial Results For First Quarter Ended 30.06.2019. (
  • From Abstract: 'This monograph reviews available information on the production, properties, and uses of high-purity and commercial forms of nickel, and on the properties and applications of its important alloys, both ferrous and non ferrous. (
  • Ranjeev Alloys Ltd has submitted to BSE the Shareholding Pattern for the Period Ended December 31, 2016. (
  • Ranjeev Alloys Ltd has informed BSE regarding Quarterly Statement on Investor Complaints / Grievances Redressal Mechanism for the Quarter ended December 31, 2016, under Regulation 13(3) of SEBI (Listing Obligations and Disclosure Requirements) Regulations, 2015. (
  • Even the best alloys can't last forever, so we applied statistical thermodynamics to materials science and found a better way to dope zirconium alloys to use in fuel rod cladding. (
  • Titan-Aluminum alloys are combining low density, high strength and oxidation resistance at elevated temperatures and are therefore of high technical relevance e.g. in aerospace engineering. (
  • Oxide dispersion strengthened (ODS) alloys are a class of materials that offer an unmatched combination of deformation-, creep-, coarsening- oxidation- and corrosion resistance at temperatures up to 1,000 °C. (
  • As is well known to those skilled in the art, certain magnetic iron-nickel alloys are particularly useful in making indicating instruments, such as magnetic speedometers, almost completely independent of variations in temperature over an unusually wide range of temperatures. (
  • If the carbon content is merely reduced, the martensitic transformation temperature is raised so that the alloy irreversibly loses its high permeability if exposed to the low temperatures to which it is often liable to be subjected in use. (
  • Cast and forged titanium alloys suited for use at temperatures over 600 C. are based on TiAl gamma phase structure. (
  • Useful alloys have about 1.5% or greater tensile ductility at temperatures of 260 C. and below, thereby making them fabricable and suited for engineering applications. (
  • The present invention relates to titanium alloys usable at high temperatures, particularly those of the TiAl gamma phase type. (
  • To be useful at higher temperatures, titanium alloys need the proper combination of properties. (
  • Most nickel alloys demonstrate strength, longevity, as well as dependability even in toughest atmospheres at high temperatures. (
  • REL61 provides significant advantages over other no-low silver alloys by offering better flow characteristics at lower temperatures, thus reducing PCB damage and assembly costs. (
  • have introduced four criteria that have to be satisfied in the selection process of alloying elements in order to obtain castable, precipitation-strengthened aluminum alloys with both high stability and strength at elevated temperatures. (
  • Affordable, lightweight and capable of withstanding temperatures 100 degrees Celsius higher than commercially available automotive cast alloys, ACMZ is proving to be suitable for the next generation of internal combustion engines, enabling the industry to advance toward its target of 54.5 miles per gallon by 2025. (
  • Current alloys inhibit engine efficiency because they soften at the peak temperatures present in highly efficient advanced engines. (
  • This book presents the state of the art concerning the fundamental aspects of semi-solid processing of alloys and composites, together with the industrial applications. (
  • The Engineered Materials division ("EMC"), which produces advanced beryllium-aluminum ("BeAl" alloy products for commercial and defense markets, achieved profitability in the quarter on sales of $1.8 million, a 55% increase over the prior-year period. (
  • Liu says that the research group's general approach was to start with a ternary iron-cobalt-nickel alloy with moderate strength and ductility. (
  • For the guide wire application, a distal core section is made of the nitinol alloy with a ternary element addition thus improving radiopacity over that of distal core section made from a binary nickel-titanium alloy. (
  • 5. The guide wire of claim 1, wherein the alloy comprises about 30 to about 52 percent titanium and the balance nickel and up to about 10 percent of one or more additional ternary alloying elements. (
  • The alloys with different compositions in the Al-rich corner of the Al-Co-Y ternary system were prepared by conventional casting and further processed by melt-spinning technique. (
  • On the other hand, just a few works have been reported for the other ternary system, Al-Co-Y alloys. (
  • The common alloys employed for making journal boxes are much dearer than a brass composed of zinc 50, and copper 56, and yet they are no harder. (
  • Some of the common alloys used in fittings and valves include C37700, C84400, C83600, and C92200, he says. (
  • Huang, P. K., Yeh, J. W., Shun, T. T. & Chen, S. K. Multi-principal-element alloys with improved oxidation and wear resistance for thermal spray coating. (
  • Early soft soldering used pure tin (Sn), yet gradually alloys were sought that would fix issues like thermal cycling, shock resistance, electron migration, and the development of whiskers in tin-based alloys. (
  • His research is combining simulations that model atomic interactions and experiments involving real-time ion irradiation exposure and mechanical testing to understand the fundamental mechanisms responsible for the alloys' thermal stability, radiation tolerance and mechanical performance. (
  • Suitable thermal and mechanical treatments will produce extensive rearrangements of the atoms in metals and alloys, and corresponding marked variations in physical and chemical properties. (
  • This makes the metal harder and more brittle than a single-phase alloy, and also affects the way the metal responds to hardening by hammering and lathing, and greatly restricts the use of mechanised techniques of manufacture. (
  • Paiste calls this Signature Bronze or Sound Formula, and for a time produced no bell metal cymbals, but now produces high-end cymbals of both this alloy and bell bronze. (
  • Wai In a series of bronze alloys containing tin \fi and copper, it was found that an excess of tin ^U was the cause of softness, while an excess of :opper, although it is such a malleable metal, is the-cause of brittleness. (
  • In alloys of copper and tin-common bronze- an excess of tin renders the alloy soft, as would be expected, because it is the softer metal. (
  • Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. (
  • In metal-based additive manufacturing, application of a direct energy source, such as a laser or electron beam, to melt alloy powders locally results in solidification rates between 0.1 m s −1 and 5 m s −1 , an order of magnitude increase over conventional casting processes. (
  • Given that rastering of this direct energy source (such that it follows a pattern of slightly overlapping lines in a back and forth pattern) to continuously fuse successive layers of powder is analogous to welding processes, it is not surprising that the suite of printable metal alloys are limited to those known to be easily weldable. (
  • The limitations of the currently printable alloys, especially with respect to specific strength, fatigue life and fracture toughness, have hindered metal-based additive manufacturing from maturing to its full potential. (
  • Figure 1: Additive manufacturing of metal alloys via selective laser melting. (
  • In this way some specific properties are improved, making the alloy more attractive than the pure metal. (
  • Bronze is harder than copper as a result of alloying that metal with tin or other metals. (
  • Master alloys are precisely calculated combinations of metal elements, occasionally with chemical additives, formed into particular alloying compounds Milward's line of master alloys for the aluminum industry include grain refiners, modifiers, and hardeners. (
  • Alloy is baser metal mixed with it. (
  • In particular, Trelewicz is interested in nanostructured metal alloys (metals mixed with other elements) that incorporate nanometer-sized features into classical materials to enhance their performance. (
  • relative freedom of a noble metal from alloy or other impurities," from Anglo-French alai , Old French aloi , from aloiier (see alloy (v.)). Meaning " base metal alloyed with a noble metal" is from c.1400. (
  • Apple's future iPods, iPads and Macs could be super-durable and lightweight, after the company signed a deal with Liquidmetal Technologies to license the latter's IP for a specialized metal alloy. (
  • Apple products could become a little lighter and a lot tougher, after the company signed an agreement with Liquidmetal Technologies to use the latter's metal alloys in their products. (
  • An amalgam is an alloy of a metal and mercury. (
  • Unfortunately for these materials scientists, the interaction of heat and gravity in a sample of molten metal creates currents of rising and falling material, preventing some metals from alloying and overwhelming the subtle interactions between molecules of pure metals and metals that do mix well. (
  • A shape memory alloy (SMA, also known as a smart metal, memory alloy, or muscle wire) is an alloy that "remembers" its shape, and can be returned to that shape after being deformed, by applying heat to the alloy. (
  • N. I. Taluts, A. V. Dobromyslov, and V. A. Elkin, "Structural and phase transformations in quenched and aged Zr-Ru alloys," J. Alloys Compd. (
  • A federal law to further reduce the amount of lead in drinking water has manufacturers of copper alloy plumbing fixtures, fittings and valves replacing their products with ones manufactured with new copper alloys that do not contain lead. (
  • The new lead-free products are giving standards-setting organizations pause because the lead-free alloys have not been fully vetted for high-pressure use. (
  • Alloy Navigator™ 5 offers a robust and comprehensive framework for IT service delivery and support, traditionally available only in high-cost enterprise-level products, yet is competitively priced. (
  • While lead (Pb) managed to fill this role for most soldering applications, the phasing out of lead from products, as well as new requirements for increasingly more fine-pitched components have required the development of new solder alloys that can fill this role. (
  • Traditional engineering resins and polymer alloys/blends have been "around" for decades and, yet, there are few studies that analyze in detail all of the major materials involved in terms of plant capacities, markets by application, new technologies and products, and rationales for anticipated growth. (
  • AIM produces advanced solder products such as solder paste, liquid flux, cored wire, bar solder, epoxies, lead-free and halogen-free solder products, and specialty alloys such as indium and gold for a broad range of industries. (
  • Early- stage research provided a fundamental breakthrough in metallurgy that was leveraged into the design of this new family of alloys. (
  • For instance, the nickel-chromium alloys (containing 15% chromium) are made use of due to the fact that it can provide oxidation including carburization resistance at temperature levels past 760 ¡ã C. (
  • A. V. Dobromyslov and V. A. Elkin, "β → α and β → ω transformations in Ti-Os alloys," Metall. (
  • Despite decades of extensive research and application, commercial aluminum alloys are still poorly understood in terms of the phase composition and phase transformations occurring during solidification, cooling, and heating. (
  • This vohune contains the papers presented at the Adriatico Research Conference on Structural and Phase Stability of Alloys held in Trieste, Italy, in May 1991, under the auspices of the International Centre for Theoretical Physics. (
  • The data is not there to support high-pressure, high-temperature' alloys, says Mark Clark, a codes and standards engineer with NIBCO INC., Elkhart, IN. (
  • A cylinder head made of lightweight, high-temperature ACMZ, a new suite of aluminum-based alloys developed by researchers at ORNL. (
  • Sales in the Copper Alloy division also were higher Q/Q and Y/Y. In the quarter, sales of $2.7 million were 31% higher than in the prior-year period, and YTD sales of $7.4 million were 20% higher than in the prior-year period. (
  • Alloy has earned a unique position as both creator and distributor of content that has captured the imagination of the millennial generation," said ZelnickMedia chief Strauss Zelnick . (
  • Indeed, the carbon content of the alloys normally used is about 0.2%, though it may vary from this by amounts which have been considered negligible but which are in fact important. (
  • The carbon content, as will be ap preciated by those skilled in the art, is diflicult to control within narrow limits, particularly if the alloy is made by melting. (
  • The alloys were manufactured by conventional and high speed solidification techniques, and their macroscopic, microscopic and nanoscale structures were studied by optical, X-ray and electron microscope methods. (
  • Recently, several new high volume automotive knuckle castings have been introduced using A356 aluminum alloy with T-6 temper. (
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