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Tu YK, Bishop AT, Kato T, Adams ML, Wood MB. Experimental carpal reverse-flow pedicle vascularized bone grafts. Part II: bone blood flow measurement by radioactive-labeled microspheres in a canine model. J Hand Surg Am 2000; 25:46-54. [PMID: 10642472 DOI: 10.1053/jhsu.2000.jhsu025a0046] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Reverse-flow pedicle vascularized bone grafts (VBGs) from the radius, commonly used for carpal nonunion and avascular necrosis, provide superior clinical results. In this experimental study bone blood flow in canine distal radius VBGs was measured to determine the status of the bone circulation immediately after elevation (group 1) and 2 weeks later (group 2). Immediate VBG flow (group 1) was substantial, but significantly less than the contralateral undisturbed distal radius (8.42 mL/min/100 g and 16.53 mL/min/100 g, respectively). At 2 weeks after surgery (group 2) VBG flow was compared with nonvascularized control grafts. Vascularized bone graft flow was significantly higher than group 1 (mean, 33.72 mL/min/100 g). Minimal flow was seen in the conventional graft control (0.62 mL/min/100 g). This study demonstrates that reverse-flow pedicle radius VBG maintain enhanced bone circulation long-term. Given the similarity of human and canine distal radius vascular anatomy, these data support the clinical use of reverse-flow VBG for carpal pathology. (J Hand Surg 2000; 25A:46-54.
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Robitaille PM, Warner R, Jagadeesh J, Abduljalil AM, Kangarlu A, Burgess RE, Yu Y, Yang L, Zhu H, Jiang Z, Bailey RE, Chung W, Somawiharja Y, Feynan P, Rayner DL. Design and assembly of an 8 tesla whole-body MR scanner. J Comput Assist Tomogr 1999; 23:808-20. [PMID: 10589553 DOI: 10.1097/00004728-199911000-00002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE The purpose of this report is to describe the design and construction of an 8 T/80 cm whole-body MRI system operating at 340 MHz. METHOD The 8 T/80 cm magnet was constructed from 414 km of niobium titanium superconducting wire. The winding of this wire on four aluminum formers resulted in a total inductance of 4,155 H. Gradient subsystems included either a body gradient or a head gradient along with a removable shim insert. The magnet and gradient subsystems were interfaced to two spectrometers. These provided the control of the gradient amplifiers and the two sets of four RF power amplifiers. The latter provide in excess of 8 kW of RF power from 10 to 140 MHz and 10 kW of RF power from 245 to 345 MHz. A dedicated computer-controlled patient table was designed and assembled. The entire system is located in a clinical setting, facilitating patient-based studies. RESULTS The 8 T/80 cm magnet was energized without complication and achieved persistent operation using 198.9 A of current, thereby storing 81.5 MJ of magnetic energy. Exceptional performance was observed for nearly all components both in isolation and when combined within the complete system. CONCLUSION An 8 T/80 cm MRI system has been assembled. The magnet subsystem is extremely stable and is characterized by good homogeneity and acceptable boil-off rates.
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Wust P, Berger J, Fähling H, Nadobny J, Gellermann J, Tilly W, Rau B, Petermann K, Felix R. Scanning E-field sensor device for online measurements in annular phased-array systems. Int J Radiat Oncol Biol Phys 1999; 43:927-37. [PMID: 10098449 DOI: 10.1016/s0360-3016(98)00490-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE A measurement device for noninvasive and simultaneous control of antennas during regional radiofrequency (rf) hyperthermia and, subsequently, the estimation of the power distribution in the interior of patients are essential preconditions for further technological progress. Aiming at this, the feasibility of an electro-optical electric field sensor was investigated during clinical rf hyperthermia. MATERIAL AND METHODS The electro-optical electric field (E-field) sensor is based on lithiumniobate crystals and the Mach-Zehnder interferometer structure, and was tested in an earlier phantom study. For this study, a mechanical scanning device was developed allowing the registration of the E-field during clinical application. Data were recorded along a curve in the water bolus of the SIGMA 60 applicator of the annular phased-array system BSD-2000 (BSD Medical Corp., Salt Lake City, UT) close to the base points of the flat biconical dipole antennas. The results were compared with modeling calculations using the finite-difference time-domain (FDTD) method. For the latter, different antenna models were assumed. For systematic registration of the E-field curves in amplitude and phase, we employed an elliptical lamp phantom with fat-equivalent ring (filled with saline solution) and an elliptical polyacrylamide phantom with acrylic glass wall. Further measurements were carried out during the treatment of 5 patients with 20 hyperthermia treatments. RESULTS Data of both phantom and patient measurements can be satisfactorily described by the FDTD method, if the antenna model is refined by taking into account the conical form of the dipoles and the special dielectric environment of the feeding point. Phase deviations can be entered ex posteriori for correction in the calculation algorithm. A comparison of amplifier power measurement (forward and backward power) and bolus E-field scans near the antenna base points demonstrates that E-field measurements between antennas and patient are a necessity for the appropriate characterization of antenna radiation properties. These measurements are sensitive to variations of the lossy medium in position and shape, and can be correctly predicted with current models. However, the differences between different patients are moderate and unspecific in both calculations and measurements, with fluctuations at maximum of 30 degrees in phases and 40% in amplitudes. CONCLUSIONS The measurement method presented here turned out to be a practical tool for online registration of E-fields in phases and amplitudes along arbitrary curves in a water bolus or phantom. It can be utilized to evaluate antenna design and modeling calculations and leads, thus, to a better understanding of complicated multiantenna systems. In clinical routine, it can be employed as input for patient-specific hyperthermia planning and, finally, for the realization of online control with subsequent optimization of the power distribution in the patient.
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Heilbronn L, Madey R, Elaasar M, Htun M, Frankel K, Gong WG, Anderson BD, Baldwin AR, Jiang J, Keane D, McMahan MA, Rathbun WH, Scott A, Shao Y, Watson JW, Westfall GD, Yennello S, Zhang WM. Neutron yields from 435 MeV/nucleon Nb stopping in Nb and 272 MeV/nucleon Nb stopping in Nb and Al. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1998; 58:3451-3461. [PMID: 11725795 DOI: 10.1103/physrevc.58.3451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Neutron fluences were measured from 435 MeV/nucleon Nb ions stopping in a Nb target and 272 MeV/nucleon Nb ions stopping in targets of Nb and Al for neutrons above 20 MeV and at laboratory angles between 3 degrees and 80 degrees. The resultant spectra were integrated over angles to produce neutron energy distributions and over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions. The angular distributions from all three systems are peaked forward, and the energy distributions from all three systems show an appreciable yield of neutrons with velocities greater than the beam velocity. Comparison of the total neutron yields from the two Nb + Nb systems suggests that the average neutron multiplicity decreases with decreasing projectile energy. Comparison of the total yields from the two 272 MeV/nucleon systems suggests that the total yields show the same dependence on projectile and target mass number as do total inclusive neutron cross sections. The data are compared with Boltzmann-Uehling-Uhlenbeck model calculations.
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Goldberg L, Koplow J, Lancaster DG, Curl RF, Tittel FK. Mid-infrared difference-frequency generation source pumped by 1.1-1.5 micrometer dual-wavelength fiber amplifier for trace-gas detection. OPTICS LETTERS 1998; 23:1517-1519. [PMID: 11763099 DOI: 10.1364/ol.23.001517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Continuous-wave mid-infrared radiation near 3.5 micrometers is generated by difference-frequency mixing of the output of a compact 1.1-1.5 micrometer dual-wavelength fiber amplifier in periodically poled LiNbO3. The diode side-pumped amplifier is constructed with double-cladding Yb-doped fiber followed by single-mode Er/Yb codoped fiber. Output powers of as much as 11 microW at 3.4 micrometers are obtained, and spectroscopic detection of CH4 and H2CO is demonstrated.
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Abstract
The design of a controlled environment electron microscope is described and examples are presented to demonstrate the information that can be obtained by studying gas-solid interactions in real time and at high spatial resolution.
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Okazaki Y, Rao S, Ito Y, Tateishi T. Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibility of new Ti alloys without Al and V. Biomaterials 1998; 19:1197-215. [PMID: 9720903 DOI: 10.1016/s0142-9612(97)00235-4] [Citation(s) in RCA: 281] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effects of various metallic ions using various metallic powders on the relative growth ratio of fibroblasts L929 and osteoblasts MC3T3-E1 cells were carried out. Ti, Zr, Sn, Nb and Ta had evidently no effect on the relative growth ratios of cells. Otherwise, Al and V ions exhibit cytotoxicity from a concentration of > or = 0.2 ppm. This Al effect on cells tend to be stronger in medium containing small quantity of V ions (< or = 0.03 ppm). The new Ti-15%Zr-4%Nb-4%Ta-0.2%Pd alloy exhibited a higher corrosion resistance in physiological saline solution. The addition of 0.02%O and 0.05%N to Ti-Zr alloy improved the mechanical properties at room temperature and corrosion fatigue strength. The relative growth ratios for the new Ti alloy plate and the alloy block extraction were unity. Further, the relative growth ratios were almost unity for the new Ti alloy against apatite ceramic pins up to 10(5) wear cycles in Eagle's MEM solution. However, there was a sharp decrease for Ti-6%Al-4%V ELI alloy from 3 x 10(4) wear cycles as V ion was released during wear into the wear test solution since the pH of the Eagle's MEM increases with increasing wear cycles.
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Scarfe WC, Farman AG, Brand JW, Kelly MS. Tissue radiation dosages using the RVG-S with and without niobium filtration. Aust Dent J 1997; 42:335-42. [PMID: 9409051 DOI: 10.1111/j.1834-7819.1997.tb00140.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Tissue doses for a modified Rando head- and-neck phantom were measured for imaging with speed group E film with standardized aluminium filtration and the RVG-S both with and without added niobium filtration. Cylindrical holes drilled into the phantom's tissue-equivalent material permitted the placement of a small ionization chamber into anatomically correct sites representing the thyroid, parotid, submandibular and sublingual glands. To establish the necessary cone positions, angulations and time settings for each exposure, diagnostically acceptable images of six teeth, representative of different intraoral regions, were made for a DXXTR mannequin. Entrance and exit points were marked and transferred to the phantom to allow reproducible repeat exposures. The RVG-S provided reductions in average skin entrance dose of 31 per cent to 39 per cent with standard aluminium filtration and 51 per cent to 60 per cent with the addition of niobium filtration to attenuate the beam. While dose reductions relative to E-speed film usage were found for deep tissue sites, these were site and projection specific. The cumulative reduction from use of the RVG-S without niobium filtration was 32 per cent. It was 42 per cent with additional niobium filtration. It should be noted, however, that adding niobium filtration resulted in increased dosages to the deeper soft tissues such as the thyroid gland.
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Murray SF, Calabrese SJ, Malanoski SB, Golding LR, Smith WA, Hamby M. Selection and evaluation of blood- and tribologically compatible journal bearing materials. ASAIO J 1997; 43:M603-8. [PMID: 9360116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A critical issue in the Cleveland Clinic Foundation (CCF) Innovative Ventricular Assist System (IVAS) blood pump is the selection of materials for the blood-lubricated journal bearing. Under normal operating conditions, the journal bearing geometry creates a thick blood film that separates the rotating and stationary surfaces. However, since start-up and certain transients could cause temporary contact, the material pair selected for these surfaces must be both tribologically and blood compatible. Combinations of two biocompatible alloys were tested: a titanium-zirconium-niobium alloy (Ti-13Zr-13Nb) and a zirconium-niobium alloy (Zr-2.5Nb). A standard pin-on-disk tester was used, with the contact surfaces lubricated by glycerol/saline mixtures simulating the viscosity range of blood. One test series evaluated start-up conditions; the other modeled a high-speed rub that might occur if the fluid film broke down. Results showed that the preoxidized Zr-2.5Nb pin/Ti-13Zr-13Nb disk combination was superior at all sliding velocities; a self-mated Zr-2.5Nb pair also showed promise. The oxide film on a self-mated Ti-13Zr-13Nb pair, and a Ti-13Zr-13Nb pin and Zr-2.5Nb disk combination did not show adequate wear life. More work remains to explain distinct performance differences of certain combinations, with more data needed on mechanical properties of thin, hard coatings on softer metal substrates.
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Cucinotta FA, Wilson JW, Townsend LW. Abrasion-ablation model for neutron production in heavy ion collisions. NUCLEAR PHYSICS. A 1997; 619:202-212. [PMID: 11541210 DOI: 10.1016/s0375-9474(97)00130-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In intermediate energy nucleus-nucleus collisions, neutron production at forward angles is observed to occur with a Gaussian shape that is centered near the beam energy and extends to energies well above that of the beam. This paper presents an abrasion-ablation model for making quantitative predictions of the neutron spectrum. To describe neutrons produced from the abrasion step of the reaction where the projectile and target overlap, we use the Glauber model and include effects of final-state interactions. We then use the prefragment mass distribution from abrasion with a statistical evaporation model to estimate the neutron spectrum resulting from ablation. Measurements of neutron production from Ne and Nb beams are compared with calculations, and good agreement is found.
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SASTRY BV, OWENS LK, BALL CO. DIFFERENCES IN THE DISTRIBUTION OF ZIRCONIUM-95 AND NIOBIUM-95 IN THE RAT. Nature 1996; 201:410-1. [PMID: 14110018 DOI: 10.1038/201410a0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Calicchia A, Gambaccini M, Indovina PL, Mazzei F, Pugliani L. Niobium/molybdenum K-edge filtration in mammography: contrast and dose evaluation. Phys Med Biol 1996; 41:1717-26. [PMID: 8884908 DOI: 10.1088/0031-9155/41/9/011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The use of a dual K-edge filter (niobium-molybdenum) with a Mo anode x-ray tube for application to mammography is investigated. The incident and transmitted energy spectral distributions are compared with those provided by a molybdenum anode molybdenum filter tube (standard source). The imaging characteristics in terms of contrast and mean glandular dose have been evaluated for various phantom thicknesses. The niobium filtration removes the molybdenum K beta line almost completely from the beam spectrum whereas a Mo filtration is needed to avoid the increases both in the low-energy component of the incident beam and in the higher energy component of the transmitted one. The contrast is improved with respect to the standard source and the mean glandular dose is only slightly increased for moderate transmission phantoms (thickness 2-4 cm).
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139
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Heilbronn L. Neutron yields from interactions of GCR-like beams in stopping targets. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1996; 17:69-76. [PMID: 11540373 DOI: 10.1016/0273-1177(95)00514-f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In order to accurately determine the radiation risk to astronauts from GCR, the nature of the secondary radiation field created by the fragmentation of GCR in shielding and tissue must be understood. Due to the their high penetrabilities, neutrons are an important component of the secondary radiation field, especially for astronauts protected by thick shielding on lunar or Martian bases. Neutron yields from 435A MeV and 272A MeV Nb stopping in Nb and Al targets are presented, along with some preliminary analysis of neutron yields from 155A MeV C stopping in Al. Energy spectra and angular distributions are shown for neutron energies above 20 MeV. The data provides some information about the dependence of the neutron yield on projectile energy and target mass. Comparisons of the data with BUU calculations are also shown.
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Wakoh M, Farman AG, Scarfe WC, Kelly MS, Kuroyanagi K. Perceptibility of defects in an aluminum test object: a comparison of the RVG-S and first generation VIXA systems with and without added niobium filtration. Dentomaxillofac Radiol 1995; 24:211-4. [PMID: 9161163 DOI: 10.1259/dmfr.24.4.9161163] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE To compare the first generation VIXA (Gendex, Milan, Italy) and the RVG-S (Trophy Radiologie, Vincennes, France) for detection of defects in an aluminium test object at various exposures both with and without added niobium filtration. METHODS Images of a 7 mm aluminium test object with defects ranging from 0.1 to 1.5 mm with standardized projection geometry. Seven dentists acted as observers. Perceptibility curves were developed for both sensors under the various filtration conditions and exposures. RESULTS At optimum exposures both the VIXA and the RVG-S permitted the same number of defects to be observed. The optimum exposures were similar for the two systems, but the dynamic range was greater for the RVG-S. Addition of niobium filtration did not appreciably alter the radiation dose required to perceive a given number of defects using either system. CONCLUSIONS The two systems performed equally at optimum exposure when the dose is approximately the same irrespective of the presence or absence of niobium filtration. Beyond the optimal level, the RVG-S outperformed the VIXA system.
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Tetradis S, Scaf G, Lurie AG, Freedman ML. Niobium filtration of conventional and high-frequency x-ray generator beams for intraoral radiography. Effects on absorbed doses, image density and contrast, and photon spectra. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 1995; 80:232-41. [PMID: 7552890 DOI: 10.1016/s1079-2104(05)80207-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have studied the effects of niobium beam filtration on absorbed doses, on image density and contrast, and on photon spectra with conventional and high-frequency dental x-ray generators. Added niobium reduced entry and superficial absorbed doses in periapical radiography by 9% to 40% with film and digital image receptors, decreased the radiation necessary to produce a given image density on E-speed film and reduced image contrast on D- and E-speed films. As shown by increased half-value layers for aluminum, titanium, and copper and by pulse-height analyses of beam spectra, niobium increased average beam energy by 6% to 19%. Despite the benefits of adding niobium on patient dose reduction and on narrowing the beams' energy spectra, the beam can be overhardened. Adding niobium, therefore, strikes the best balance between radiation dose reduction and beam attenuation, with its risks of increased exposure times, motion blur, and diminished image contrast, when it is used at modest thicknesses (30 microns) and at lower kVp (70) settings.
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Ito A, Okazaki Y, Tateishi T, Ito Y. In vitro biocompatibility, mechanical properties, and corrosion resistance of Ti-Zr-Nb-Ta-Pd and Ti-Sn-Nb-Ta-Pd alloys. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1995; 29:893-9. [PMID: 7593029 DOI: 10.1002/jbm.820290715] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
There is much discussion about the toxic effect of vanadium and aluminum contained in Ti-6Al-4V alloy for prosthetic implants. The goal of the present investigation was to develop new titanium alloys with sufficient mechanical properties using more biocompatible alloying elements: zirconium, tin, niobium, tantalum, and palladium. The relative growth rates of L929 and MC3T3-E1 cells were significantly higher when cultured with the extraction of Ti-10Zr-8Nb-2Ta-0.2Pd or Ti-15Zr-4Nb-2Ta-0.2Pd alloys than when cultured with the extraction of Ti-6Al-4AV ELI alloy. The tensile strength, elongation, and reduction of area for Ti-15Sn-4Nb-2Ta-0.2Pd alloy were 989 MPa, 14.4%, and 49.3%, respectively, surpassing Ti-6Al-4V ELI alloy. (ASTM F138-84); those for Ti-15Zr-4Nb-2Ta-0.2Pd alloy were 725 MPa, 23.6% and 54.9%, respectively. More than 15% addition of tin as well as zirconium deteriorated the tensile properties. Titanium release into a 5% hydrochloric acid solution from the new titanium alloys was 20-50 micrograms/cm2 per day, though that from Ti-6Al-4V ELI alloy was 1300 micrograms/cm2 per day. The optimum alloy compositions are Ti-15Zr-4Nb-2Ta-0.2Pd and Ti-15Sn-4Nb-2Ta-0.2Pd, judging from cytocompatibility, corrosion resistance, and mechanical properties. The former is characterized by its higher level cytocompatibility and corrosion resistance, while the latter is characterized by mechanical properties.
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Tao F, Powers-Risius P, Alpen EL, Medvedovsky C, David J, Worgul BV. Radiation effects on late cytopathological parameters in the murine lens relative to particle fluence. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:483-491. [PMID: 11539985 DOI: 10.1016/0273-1177(94)90503-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Lenses of mice irradiated with 250 MeV protons, 670 MeV/amu 20Ne, 600 MeV/amu 56Fe, 600 MeV/amu 93Nb and 593 MeV/amu 139La ions were evaluated by analyzing cytopathological indicators which have been implicated in the cataractogenic process. The LETs ranged from 0.40 keV/micrometer to 953 keV/micrometer and fluences from 1.31 10(3)/mm2 to 4.99 x 10(7)/mm2. 60Co gamma-rays were used as the reference radiation. The doses ranged from 10 to 40 cGy. The lenses were assessed 64 weeks post irradiation in order to observe the late effects of LET and dose on the target cell population of the lens epithelium. Our study shows that growth dependent pathological changes occur at the cellular level as a function of dose and LET. The shapes of the RBE-LET and RBE-dose curves are consistent with previous work on eye and other biological systems done in both our laboratory and others. The RBEmax's were estimated, for the most radiation cataract related cytological changes, MN frequency and MR disorganization, by calculating the ratio of the initial slopes of dose effect curve for various heavy ions to that of 60Co gamma-ray. For each ion studied, the RBEmax derived from micronucleus (MN) frequency is similar to that derived from meridional row (MR) disorganization, suggesting that heavy ions are equally efficient at producing each type of damage. Furthermore, on a per particle basis (particle/cell nucleus), both MN frequency and MR disorganization are LET dependent indicating that these classic precataractogenic indicators are multi-gene effects. Poisson probability analysis of the particle number traversing cell nuclei (average area = 24 micrometers2) suggested that single nuclear traversals determine these changes. By virtue of their precataractogenic nature the data on these endpoints intimate that radiation cataract may also be the consequence of single hits. In any case, these observations are consistent with the current theory of the mechanism of radiation cataractogenesis, which proposes that genomic damage to the epithelial cells surviving the exposure is responsible for opacification.
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Rabin BM, Joseph JA, Hunt WA, Dalton TB, Kandasamy SB, Harris AH, Ludewigt B. Behavioral endpoints for radiation injury. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:457-466. [PMID: 11539983 DOI: 10.1016/0273-1177(94)90500-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The relative behavioral effectiveness of heavy particles was evaluated. Using the taste aversion paradigm in rats, the behavioral toxicity of most types of radiation (including 20Ne and 40Ar) was similar to that of 60Co photons. Only 56Fe and 93Nb particles and fission neutrons were significantly more effective. Using emesis in ferrets as the behavioral endpoint, 56Fe particles and neutrons were again the most effective; however, 60Co photons were significantly more effective than 18 MeV electrons. These results suggest that LET does not completely predict behavioral effectiveness. Additionally, exposing rats to 10 cGy of 56Fe particles attenuated amphetamine-induced taste aversion learning. This behavior is one of a broad class of behaviors which depends on the integrity of the dopaminergic system and suggests the possibility of alterations in these behaviors following exposure to heavy particles in a space radiation environment.
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Carr KE, McCullough JS, Brennan P, Hayes TL, Ainsworth EJ, Nelson AC. Heavy ion induced changes in small intestinal parameters. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:521-530. [PMID: 11539988 DOI: 10.1016/0273-1177(94)90507-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effects on 17 different structural parameters of mouse small intestine three days after treatment with three types of heavy ion (neon, iron and niobium) are compared, the first two being of particular relevance to space flight. The data for niobium are given in full, showing that changes after niobium ion treatment are not standard and are concentrated in the epithelial compartment, with few of the parameters having a response which is dose dependent. When comparisons are made for the three types of heavy ion, the damage is greatest after neon ion irradiation, implying that the additional non-epithelial damage produced as LET rises from X rays through neutrons to neon ions is not necessarily maintained as LET continues to rise. Further understanding is therefore needed of the balance between changes affecting the vascular and absorptive components of the organ. Variation from group to group is also important, as is variation of strain or gastrointestinal status. All such factors are important in the understanding of changes in multicellular organs after exposure to heavy ion radiation.
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MESH Headings
- Animals
- Dose-Response Relationship, Radiation
- Female
- Intestine, Small/cytology
- Intestine, Small/pathology
- Intestine, Small/radiation effects
- Intestine, Small/ultrastructure
- Iron
- Linear Energy Transfer
- Mice
- Mice, Inbred Strains
- Microscopy, Electron, Scanning
- Neon
- Niobium
- Radiation, Ionizing
- Resins, Plant
- Statistics, Nonparametric
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Borden DR, Farman AG, Yancey J, Kelley MS. Direct digital imaging with and without niobium filtration for detection of density differences beneath steel orthodontic bands. Dentomaxillofac Radiol 1994; 23:135-7. [PMID: 7835513 DOI: 10.1259/dmfr.23.3.7835513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
An in vitro investigation was carried out to determine the efficacy of the RVG 32000 (Trophy Radiologie, Vincennes, France) in detecting subtle density variations in a standard aluminum test object through steel orthodontic bands. The density variations were of the same magnitude as those found when dental caries develops beneath bands during orthodontic therapy. The procedure was carried out with both standard aluminum filtration and added niobium filtration. This study revealed the imaging system to have a wide recording latitude with no significant differences in the diagnostic decisions being made between with entrance doses ranging from 189-517 microGy without niobium, and 169-267 microGy with added niobium. No significant difference was found between the diagnostic yield of images made with and without added niobium filtration. The accuracy was 89% with added niobium and 90% without added niobium. Specificity was 99% for both filtration conditions. It was generally possible to detect defects as small as 0.2-0.3 mm in 7 mm of aluminum through 0.26 mm steel orthodontic band material. It is concluded that the RVG 32000 has a wide recording latitude which permits detection of small density changes beneath orthodontic band material. The addition of niobium filtration did not interfere with this diagnostic task.
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Abstract
An instrumented spinal fixation device has been developed that allows in vivo measurement of the forces and moments acting on the implant. The telemetry is inductively powered, hermetically sealed by electron beam welding and is active only during the measurements. The instrumented fixateur interne is similar in size to the original Dick internal fixator implant and has the strength of the original implant. Laboratory tests with paired implants mounted in plastic vertebrae show that small changes in the position of the implants have a strong influence on the distribution of the loads on the implants.
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148
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Mariolani JR, Belangero WD, de Arruda AC. Triage methodology for the evaluation of implant-bone interfaces. Biomaterials 1994; 15:615-20. [PMID: 7948581 DOI: 10.1016/0142-9612(94)90212-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Stainless steel plugs coated with and without Al2O3, TiO2 and Nb2O5 were inserted into canine femora in order to develop a methodology of rapid identification of appropriate specimens for deeper analysis of implant-bone interfaces. This approach is especially meaningful in areas where research funds are scarce. After a maximum follow-up period of 52 wk, bone segments containing plugs were radiographed using conventional techniques, high resolution techniques (which allowed a good preliminary evaluation) and microradiography. Analysis by X-ray fluorescence spectrometry indicated release of the materials by the implants. Microdensitometry of the microradiographs allowed a precise thickness determination of the tissue formed around the implants.
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149
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Wakoh M, Farman AG, Nishikawa K, Kuroyangi K. Quantitative assessment of image quality using niobium filtration for cephalometric radiography. Dentomaxillofac Radiol 1994; 23:73-5. [PMID: 7835506 DOI: 10.1259/dmfr.23.2.7835506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The effect of added niobium filtration on image quality in cephalometric radiography was quantitatively evaluated using the Modulation Transfer Function (MTF). A conventional full-wave cephalometric X-ray generator (Quint Sectograph) and a constant potential, high frequency X-ray generator (Orthophos CD) were compared with respect to the effects on the MTF of the added filtration. There was a slight reduction in image quality with both machines when adding niobium filtration.
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150
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Ahlner BH, Lind MG. The effect of irradiation on blood flow through rabbit submandibular glands. Eur Arch Otorhinolaryngol 1994; 251:72-5. [PMID: 8024764 DOI: 10.1007/bf00179895] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Microspheres labelled with radioactive isotopes were used to study blood flow through irradiated rabbit submandibular glands before and after injection of pilocarpine. The blood flow through the submandibular glands was measured by the microsphere technique with satisfactory accuracy. A single radiation dose of 13.1 Gy at 3 months of age reduced blood flow through the whole gland significantly 4 months later, and even more at 10 months after irradiation. However, the relative blood flow (per gram of gland tissue) was almost unaffected at both 4 and 10 months post-irradiation with 13.1 Gy because of the simultaneous reduction of gland parenchyma.
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