(n.) A rare element of the vanadium group, first found in a variety of the mineral columbite occurring in Connecticut, probably at Haddam. Atomic weight 94.2. Symbol Cb or Nb. Now more commonly called niobium.
Example Sentences:
(1) The comparative materials were the Co-Cr-alloys Remanium CD and Wirobond and the implant materials Titanium, Tantalum and Columbium and the high biocompatible material Teflon.
Niobium
Definition:
(n.) A later name of columbium. See Columbium.
Example Sentences:
(1) Tantalum (Ta), niobium (Nb) and commercially pure titanium (c.p.
(2) The aim of this study was to investigate the incidence of cancer among 318 male employees of a niobium mining company which was only operated between 1951 and 1965.
(3) The addition of niobium resulted in an increase in relative exposure of 30.6% at 70 kVp and 10.7% at 90 kVp at a depth of 6 cm.
(4) Additional niobium caused an increase in the film speed produced by the half-wave units, especially in the case of the lower kilovoltage, less filtered beam.
(5) Investigations with mice have shown, that niobium powder is insoluble, does not irritate tissues and is not resorbed.
(6) With particular regard to Aluminium filters, whose prices are far lower than Niobium ones, it has to be pointed out that: 1) in order to have the same air-Kerma reduction the Aluminium filter thickness must be quite heavy (2.8 mm) which causes practical problems of use; 2) the Aluminium filter causes image quality loss especially at lower kVs.
(7) The skin exposures from an X-ray beam with the added niobium filter and a beam with the aluminum filter alone were measured and compared.
(8) The titanium-aluminum-niobium alloy is extremely biocompatible and enables the fast ongrowth of newly formed osseous tissue to act as secondary stabilization.
(9) Radiation dose distributions measured in a Rando phantom revealed a higher reduction in the patient dose with the niobium filter.
(10) The performance of a niobium filter, with K-edge at 19 keV, and a copper filter have been studied concerning absorbed dose, image quality and tube loading.
(11) Thyroid dose was not lessened by using the niobium filter, however.
(12) Either a 0.05 mm niobium filter or a 0.10 mm copper filter was placed into the beam from an X-ray tube.
(13) In this study the authors discuss parameters which influence the emission spectrum of x-rays and criteria that have an influence on their distribution (anode current, tension), and they draw attention to the materials most frequently used for filter construction-niobium in particular.
(14) Niobium-95 with low average beta energy (0.043 MeV (100%)) does not increase the total dose to the GI tract significantly despite its longer retention in the intestine.
(15) This investigation studied the effect of adding niobium filtration to the dental x-ray beam assessing reduction in patient x-ray exposure and changes in image quality.
(16) Tungsten, niobium, and tantalum, but not manganese, chromium, or molybdenum, substituted for vanadium to form enzyme-activating complexes with glutathione.
(17) Radiographic contrast decreased linearly as the half-value layer increased (r2 = 0.956, P less than 0.0005), and no specific effects of constant potential or niobium filtration were revealed.
(18) The copper filter reduced skin doses more than the niobium filter did, and caused less increase in tube loading.
(19) These results support the values currently used for radiological protection purposes to calculate doses from the ingestion of niobium isotopes; these are 1% for adults and 2% for infants in the first year of life.
(20) In vitro experiments have been carried out to study the solubility and metabolic behaviour in human lung tissue and plasma of hard metal alloy constituents such as cobalt, tungsten, tantalum, titanium and niobium.