(n.) A heavy mineral of an iron-black color and submetallic luster. It is essentially a tantalate of iron.
Example Sentences:
(1) He believes the war in eastern Congo – which began in reprisal against perpetrators of the 1994 Rwandan genocide and has evolved into a frenzied scramble for mineral wealth, especially for the prized colombo-tantalite (coltan), crucial for the production of microchips – has been allowed to continue because of discrimination by the international community.
Tantalum
Definition:
(n.) A rare nonmetallic element found in certain minerals, as tantalite, samarskite, and fergusonite, and isolated as a dark powder which becomes steel-gray by burnishing. Symbol Ta. Atomic weight 182.0. Formerly called also tantalium.
Example Sentences:
(1) Ultra thin, even, and grainless tantalum films have been found effective in eliminating the charging artifacts caused by external fields, and the decoration artifacts caused by crystal growth as seen in gold films.
(2) Lungs with tantalum powder were not measurably influenced by the bronchographic agents.
(3) Tantalum (Ta), niobium (Nb) and commercially pure titanium (c.p.
(4) The qualification of tantalum wire as suture material was tested by means of physical and histological investigations.
(5) The parent nuclide, W-178 (half-life 21.7 d), was produced in the Michigan State University cyclotron by proton bombardment of stacked natural tantalum-foil targets.
(6) Nineteen patients with mainly cervical tracheal stenoses (12 patients) were investigated in order to examine if a functional X-ray-diagnostic procedure (X-ray-cinetracheobronchography--CTBG--of the central airways in several beam-directions during forced breathing, cough and Valsalva-maneuver after contrasting of the trachea and main-bronchi with powdered tantalum) yields an increase of findings in comparison with a static roentgenologic procedure (chest films p. a. and frontal; tomography) and an endoscopic examination.
(7) Airway reactivity as assessed by methacholine challenge did not explain the difference in response to tantalum in the third group.
(8) In two to six weeks old autografts removed one to three hours after particle injection, the reconstituted marginal zones contained practically all of the sequestered tantalum.
(9) Segmental contraction was determined by cineroentgenography of implanted tantalum markers.
(10) In a rare case of simultaneous glottic and supraglottic webbing a tantalum keel, as described by McNaught, and a silcone elastomer keel, as described by Montgomery, were placed simultaneously via laryngofissure.
(11) Electronic scanning-slit fluorography involves replacing paired fore and aft slits for scatter rejection with only one beam-defining tantalum fore aperture.
(12) As a step toward developing the capabilities of this type of x-ray microscopy, a tantalum x-ray laser at 44.83 angstrom wavelength was used together with an x-ray zone plate lens to image both unlabeled and selectively gold-labeled dried rat sperm nuclei.
(13) Changes in secretion were measured in an exposed section of tantalum-coated tracheal epithelium.
(14) Tantalum markers were implanted in the femur, in the tibia, and in the graft for roentgen stereophotogrammetric analysis (RSA) of the sagittal laxity and the migration of the bony ends of the graft.
(15) Dose-response curves to each agonist were generated in random order, and tantalum bronchograms and simultaneous measurements of pulmonary resistance (RL) and dynamic pulmonary compliance (Cdyn) were obtained at the plateau of the response of each dose of agonist after intravenous (iv) infusion.
(16) Late occlusion (within 4 months) was mainly caused by thrombosis at the tantalum ring and improper usage.
(17) Further demonstration of the collateral pathways was done by use of 1 micrometer sized particles of tantalum.
(18) An anterior commissure laryngoplasty with placement of a tantalum splint has been employed to adjust vocal fold tension in nine cases.
(19) Metallic implants (tantalum balls, 0.5 mm in diameter) were inserted in the calvaria during surgery, and the child was examined postoperatively by roentgen stereometry at intervals of about 100 days (total observation time, 309 days).
(20) Small Tantalum markers were inserted into the anteromedial aspect of the proximal tibial metaphysis 1 cm distal to the proximal tibial growth plate in all of the animals, control and experimental, 2 weeks prior to the onset of electrical stimulation.