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Sample records for metal implanted germanium

  1. Mesostructured metal germanium sulfides

    Energy Technology Data Exchange (ETDEWEB)

    MacLachlan, M.J.; Coombs, N.; Bedard, R.L.; White, S.; Thompson, L.K.; Ozin, G.A.

    1999-12-29

    A new class of mesostructured metal germanium sulfide materials has been prepared and characterized. The synthesis, via supramolecular assembly of well-defined germanium sulfide anionic cluster precursors and transition-metal cations in formamide, represents a new strategy for the formation of this class of solids. A variety of techniques were employed to examine the structure and composition of the materials. Structurally, the material is best described as a periodic mesostructured metal sulfide-based coordination framework akin to periodic hexagonal mesoporous silica, MCM-41. At the molecular scale, the materials strongly resemble microstructured metal germanium sulfides, in which the structure of the [Ge{sub 4}S{sub 10}]{sup 4{minus}} cluster building-blocks are intact and linked via {mu}-S-M-S bonds. Evidence for a metal-metal bond in mesostructured Cu/Ge{sub 4}S{sub 10} is also provided.

  2. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dytlewski, N.; Evans, P.J.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J. [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll

    1996-12-31

    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  3. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dytlewski, N; Evans, P J; Noorman, J T [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L S [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll

    1997-12-31

    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  4. Method of beryllium implantation in germanium substrate

    International Nuclear Information System (INIS)

    Kagawa, S.; Baba, Y.; Kaneda, T.; Shirai, T.

    1983-01-01

    A semiconductor device is disclosed, as well as a method for manufacturing it in which ions of beryllium are implanted into a germanium substrate to form a layer containing p-type impurity material. There after the substrate is heated at a temperature in the range of 400 0 C. to 700 0 C. to diffuse the beryllium ions into the substrate so that the concentration of beryllium at the surface of the impurity layer is in the order of 10 17 cm- 3 or more. In one embodiment, a p-type channel stopper is formed locally in a p-type germanium substrate and an n-type active layer is formed in a region surrounded by, and isolated from, the channel stopper region. In another embodiment, a relatively shallow p-type active layer is formed at one part of an n-type germanium substrate and p-type guard ring regions are formed surrounding, and partly overlapping said p-type active layer. In a further embodiment, a p-type island region is formed at one part of an n-type germanium substrate, and an n-type region is formed within said p-type region. In these embodiments, the p-type channel stopper region, p-type guard ring regions and the p-type island region are all formed by implanting ions of beryllium into the germanium substrate

  5. Vacancy-acceptor complexes in germanium produced by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Feuser, U.; Vianden, R. (Inst. fuer Strahlen- und Kernphysik, Univ. Bonn (Germany)); Alves, E.; Silva, M.F. da (Dept. de Fisica, ICEN/LNETI, Sacavem (Portugal)); Szilagyi, E.; Paszti, F. (Central Research Inst. for Physics, Hungarian Academy of Sciences, Budapest (Hungary)); Soares, J.C. (Centro de Fisica Nuclear, Univ. Lisbon (Portugal))

    1991-07-01

    Combining results obtained by the {gamma}-{gamma} perturbed angular correlation method, Rutherford backscattering and elastic recoil detection of hydrogen, a defect complex formed in germanium by indium implantation is identified as a vacancy trapped by the indium probe. (orig.).

  6. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  7. Lattice site and thermal stability of transition metals in germanium

    CERN Document Server

    Augustyns, Valérie; Pereira, Lino

    Although the first transistor was based on germanium, current chip technology mainly uses silicon due to its larger abundance, a lower price and higher quality silicon-oxide. However, a very important goal in microelectronics is to obtain faster integrated circuits. The advantages of germanium compared to silicon (e.g. a higher mobility of the charge carriers) motivates further research on germanium based materials. Semiconductor doping (e.g. introducing impurities into silicon and germanium in order to alter - and control - their properties) can be done by ion implantation or by in situ doping, whereby the host material is doped during growth. This thesis focuses on introducing dopants by ion implantation. The implantation as well as the subsequent measurements were performed in ISOLDE (CERN) using the emission channeling technique. Although ion implantation generates undesired defects in the host material (e.g. vacancies), such damage can be reduced by performing the implantation at an elevated temperature....

  8. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.

    2010-04-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  9. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.; Kube, R.; Bracht, Hartmut A.; Grimes, Robin W.; Schwingenschlö gl, Udo

    2010-01-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  10. Ion implantation of boron in germanium

    International Nuclear Information System (INIS)

    Jones, K.S.

    1985-05-01

    Ion implantation of 11 B + into room temperature Ge samples leads to a p-type layer prior to any post implant annealing steps. Variable temperature Hall measurements and deep level transient spectroscopy experiments indicate that room temperature implantation of 11 B + into Ge results in 100% of the boron ions being electrically active as shallow acceptor, over the entire dose range (5 x 10 11 /cm 2 to 1 x 10 14 /cm 2 ) and energy range (25 keV to 100 keV) investigated, without any post implant annealing. The concentration of damage related acceptor centers is only 10% of the boron related, shallow acceptor center concentration for low energy implants (25 keV), but becomes dominant at high energies (100 keV) and low doses ( 12 /cm 2 ). Three damage related hole traps are produced by ion implantation of 11 B + . Two of these hole traps have also been observed in γ-irradiated Ge and may be oxygen-vacancy related defects, while the third trap may be divacancy related. All three traps anneal out at low temperatures ( 0 C). Boron, from room temperature implantation of BF 2 + into Ge, is not substitutionally active prior to a post implant annealing step of 250 0 C for 30 minutes. After annealing additional shallow acceptors are observed in BF 2 + implanted samples which may be due to fluorine or flourine related complexes which are electrically active

  11. Long-wavelength germanium photodetectors by ion implantation

    International Nuclear Information System (INIS)

    Wu, I.C.; Beeman, J.W.; Luke, P.N.; Hansen, W.L.; Haller, E.E.

    1990-11-01

    Extrinsic far-infrared photoconductivity in thin high-purity germanium wafers implanted with multiple-energy boron ions has been investigated. Initial results from Fourier transform spectrometer(FTS) measurements have demonstrated that photodetectors fabricated from this material have an extended long-wavelength threshold near 192μm. Due to the high-purity substrate, the ability to block the hopping conduction in the implanted IR-active layer yields dark currents of less than 100 electrons/sec at temperatures below 1.3 K under an operating bias of up to 70 mV. Optimum peak responsivity and noise equivalent power (NEP) for these sensitive detectors are 0.9 A/W and 5 x 10 -16 W/Hz 1/2 at 99 μm, respectively. The dependence of the performance of devices on the residual donor concentration in the implanted layer will be discussed. 12 refs., 4 figs

  12. Ion implantation of metals

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1976-01-01

    In this part of the paper descriptions are given of the effects of ion implantation on (a) friction and wear in metals; and (b) corrosion of metals. In the study of corrosion, ion implantation can be used either to introduce a constituent that is known to convey corrosion resistance, or more generally to examine the parameters which control corrosion. (U.K.)

  13. Ion implantation in metals

    International Nuclear Information System (INIS)

    Vook, F.L.

    1977-02-01

    The application of ion beams to metals is rapidly emerging as a promising area of research and technology. This report briefly describes some of the recent advances in the modification and study of the basic properties of metals by ion implantation techniques. Most of the research discussed illustrates some of the new and exciting applications of ion beams to metals which are under active investigation at Sandia Laboratories, Albuquerque

  14. Controlled localised melting in silicon by high dose germanium implantation and flash lamp annealing

    International Nuclear Information System (INIS)

    Voelskow, Matthias; Skorupa, Wolfgang; Pezoldt, Joerg; Kups, Thomas

    2009-01-01

    High intensity light pulse irradiation of monocrystalline silicon wafers is usually accompanied by inhomogeneous surface melting. The aim of the present work is to induce homogeneous buried melting in silicon by germanium implantation and subsequent flash lamp annealing. For this purpose high dose, high energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp irradiation at high energy densities leads to local melting of the germanium rich buried layer, whereby the thickness of the molten layer depends on the irradiation energy density. During the cooling down epitaxial crystallization takes place resulting in a largely defect-free layer. The combination of buried melting and dopant segregation has the potential to produce unusually buried doping profiles or to create strained silicon structures.

  15. Buried melting in germanium implanted silicon by millisecond flash lamp annealing

    International Nuclear Information System (INIS)

    Voelskow, Matthias; Yankov, Rossen; Skorupa, Wolfgang; Pezoldt, Joerg; Kups, Thomas

    2008-01-01

    Flash lamp annealing in the millisecond range has been used to induce buried melting in silicon. For this purpose high dose high-energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp treatment at high energy densities leads to local melting of the germanium rich layer. The thickness of the molten layer has been found to depend on the irradiation energy density. During the cool-down period, epitaxial crystallization takes place resulting in a largely defect-free layer

  16. Porous metal for orthopedics implants

    OpenAIRE

    Matassi, Fabrizio; Botti, Alessandra; Sirleo, Luigi; Carulli, Christian; Innocenti, Massimo

    2013-01-01

    Porous metal has been introduced to obtain biological fixation and improve longevity of orthopedic implants. The new generation of porous metal has intriguing characteristics that allows bone healing and high osteointegration of the metallic implants. This article gives an overview about biomaterials properties of the contemporary class of highly porous metals and about the clinical use in orthopaedic surgery.

  17. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dong, E-mail: wang.dong.539@m.kyushu-u.ac.jp; Maekura, Takayuki; Kamezawa, Sho [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Yamamoto, Keisuke; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  18. Recrystallization behaviour and electrical properties of germanium ion implanted polycrystalline silicon films

    International Nuclear Information System (INIS)

    Kang, Myeon-Koo; Matsui, Takayuki; Kuwano, Hiroshi

    1996-01-01

    The recrystallization behaviour of undoped and phosphorus-doped polycrystalline silicon films amorphized by germanium ion implantation at doses ranging from 1 x 10 15 to 1 x 10 16 cm -2 are investigated, and the electrical properties of phosphorus-doped films after recrystallization are studied. The phosphorus doping concentration ranges from 3 x 10 18 to 1 x 10 20 cm -3 . It is found that the nucleation rate decreases for undoped films and increases for phosphorus-doped films with increasing germanium dose; the growth rates decrease for both doped and undoped films. The decrease in nucleation rate is caused by the increase in implantation damage. The decrease in growth rate is considered to be due to the increase in lattice strain. The grain size increases with germanium dose for undoped films, but decreases for phosphorus-doped films. The dependence of the electrical properties of the recrystallized films as a function of phosphorus doping concentration with different germanium doses can be explained in terms of the grain size, crystallinity and grain boundary barrier height. (Author)

  19. Search for an anomalous near-surface yield deficit in Rutherford backscattering spectra from implanted germanium and silicon

    International Nuclear Information System (INIS)

    Lawson, E.M.; Appleton, B.R.

    1983-09-01

    Rutherford backscattering and channelling analysis of high-dose, room-temperature, ion-implanted germanium has revealed an anomalous near-surface yield deficit. Implant dose and species dependencies and the effect of annealing have been examined. A marked loss of implanted impurity was also noted. The yield deficit is attributed to the absorption of oxygen and other light mass contaminants into a highly porous implanted layer upon exposure to air. Loss of implant species is attributed to enhanced sputtering effects

  20. Ion implantation and amorphous metals

    International Nuclear Information System (INIS)

    Hohmuth, K.; Rauschenbach, B.

    1981-01-01

    This review deals with ion implantation of metals in the high concentration range for preparing amorphous layers (>= 10 at%, implantation doses > 10 16 ions/cm 2 ). Different models are described concerning formation of amorphous phases of metals by ion implantation and experimental results are given. The study of amorphous phases has been carried out by the aid of Rutherford backscattering combined with the channeling technique and using transmission electron microscopy. The structure of amorphous metals prepared by ion implantation has been discussed. It was concluded that amorphous metal-metalloid compounds can be described by a dense-random-packing structure with a great portion of metal atoms. Ion implantation has been compared with other techniques for preparing amorphous metals and the adventages have been outlined

  1. Lattice damage in ion-implanted silicon-germanium alloys

    International Nuclear Information System (INIS)

    Haynes, T.E.; Holland, O.W.

    1992-08-01

    The damage produced in Si 1-x Ge x alloys (0≤x≤1) by implantation of 70--100 keV 30 Si + has been measured as a function of temperature and fluence by ion channeling. For all compositions, the damage efficiency decreased sharply as the implant temperature was increased between room temperature and 150 degrees C. Furthermore, the damage efficiency in alloys of intermediate compositions (0.34≤x≤0.5) exceeds that in Ge, especially at elevated temperatures, despite the larger cascade energy density in Ge. It is shown that this behavior can be described based on a model in which the point-defect mobility is the dominant factor controlling damage retention, rather than the cascade energy density. This approach provides a framework for understanding other temperature-dependent phenomena related to damage growth in Si-Ge alloys including dose-rate effects and damage saturation in MeV implantation

  2. Blocking germanium diffusion inside silicon dioxide using a co-implanted silicon barrier

    Science.gov (United States)

    Barba, D.; Wang, C.; Nélis, A.; Terwagne, G.; Rosei, F.

    2018-04-01

    We investigate the effect of co-implanting a silicon sublayer on the thermal diffusion of germanium ions implanted into SiO2 and the growth of Ge nanocrystals (Ge-ncs). High-resolution imaging obtained by transmission electron microscopy and energy dispersive spectroscopy measurements supported by Monte-Carlo calculations shows that the Si-enriched region acts as a diffusion barrier for Ge atoms. This barrier prevents Ge outgassing during thermal annealing at 1100 °C. Both the localization and the reduced size of Ge-ncs formed within the sample region co-implanted with Si are observed, as well as the nucleation of mixed Ge/Si nanocrystals containing structural point defects and stacking faults. Although it was found that the Si co-implantation affects the crystallinity of the formed Ge-ncs, this technique can be implemented to produce size-selective and depth-ordered nanostructured systems by controlling the spatial distribution of diffusing Ge. We illustrate this feature for Ge-ncs embedded within a single SiO2 monolayer, whose diameters were gradually increased from 1 nm to 5 nm over a depth of 100 nm.

  3. Radiation defects in Te-implanted germanium. Electron microscopy and computer simulation studies

    International Nuclear Information System (INIS)

    Kalitzova, M.G.; Karpuzov, D.S.; Pashov, N.K.

    1985-01-01

    Direct observation of radiation damage induced by heavy ion implantation in crystalline germanium by means of high-resolution electron microscopy is reported. The dark-field lattice imaging mode is used, under conditions suitable for object-like imaging. Conventional TEM is used for estimating the efficiency of creating visibly damaged regions. Heavy ion damage clusters with three types of inner structure are observed: with near-perfect crystalline cores, and with metastable and stable amorphous cores. The MARLOWE computer code is used to simulate the atomic collision cascades and to obtain the lateral spread distributions of point defects created. A comparison of high-resolution electron microscopy (HREM) with computer simulation results shows encouraging agreement for the average cluster dimensions and for the lateral spread of vacancies and interstitials. (author)

  4. He reemission implanted in metals

    International Nuclear Information System (INIS)

    Tanabe, T.

    2014-01-01

    Highlights: • Observation of He reemission of various metals under He + implantation at wide temperature range. • Materials examined are aluminum (Al), Nickel (Ni) and molybdenum (Mo). • He reemission is quite temperature dependent and different with materials. • Three metals show similar dependence on temperature normalized with respective melting point. • He reemission is successfully correlated with He behavior in metals. - Abstract: Helium (He) reemission of Al, Ni and Mo under energetic He implantation (10–30 keV) in wide temperature range is studied to understand behavior of implanted He in correlation with structure changes. The reemission behavior is categorized into 4 different temperature ranges with the normalized temperature (T m ) to the melting point of each metal. At elevated temperatures (well above ∼0.6 T m ), interstitial He atoms and/or He-vacancy (ies) clusters can migrate remaining no structure change and showing smooth reemission without any burst. Between ∼0.25 and 0.6 T m , He reemission always accompanies significant structure modification. For ∼04–0.6 T m , implanted He coalesce to make bubbles and the bubbles can move to the surface. Bubble migration accompanies materials flow to the surface resulting in fuzz surface or columnar structure, depending on implantation flux. Slower bubble motion at ∼0.25–0.4 prohibits the material migration. Instead the bubbles coalesce to grow large and multi-layered blistering appears as periodic reemission behavior. Below ∼0.25 T m , He migration is too slow for bubbles to grow large, but bubble density increases up to a certain fluence, where neighboring bubbles start to coalesce. Accordingly, He release is mostly caused by mechanical failure or blister rapture. With increasing fluence, all defects (bubbles and dislocation loops) tangle or inter connected with neighboring defects and accordingly He migration to the surface along the tangled or connected defects is enhanced

  5. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Napolitani, E. [MATIS IMM-CNR at Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Impellizzeri, G. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Giarola, M. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); De Salvador, D. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Privitera, V.; Priolo, F. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Mariotto, G. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); Carnera, A. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-31

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm{sup −1}, due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm{sup −1}, which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm{sup −1} is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm{sup −1}.

  6. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    International Nuclear Information System (INIS)

    Sanson, A.; Napolitani, E.; Impellizzeri, G.; Giarola, M.; De Salvador, D.; Privitera, V.; Priolo, F.; Mariotto, G.; Carnera, A.

    2013-01-01

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm −1 , due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm −1 , which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm −1 is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm −1

  7. High level active n+ doping of strained germanium through co-implantation and nanosecond pulsed laser melting

    Science.gov (United States)

    Pastor, David; Gandhi, Hemi H.; Monmeyran, Corentin P.; Akey, Austin J.; Milazzo, Ruggero; Cai, Yan; Napolitani, Enrico; Gwilliam, Russell M.; Crowe, Iain F.; Michel, Jurgen; Kimerling, L. C.; Agarwal, Anuradha; Mazur, Eric; Aziz, Michael J.

    2018-04-01

    Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm-3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm-3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.

  8. The electronic and optical properties of germanium tellurite glasses containing various transition metal oxides

    International Nuclear Information System (INIS)

    Khan, M.N.

    1988-01-01

    Various transition metal oxides, such as TiO 2 , V 2 O 5 , NiO, CuO, and ZnO are added to germanium-tellurite glass and measurements are reported of the electrical conductivity, density, optical absorption, infra-red absorption spectra, and electron spin resonance. It is found that the d.c. conductivity of glasses containing the same amount of V 2 O 5 is higher than that of germanium tellurite glasses containing a similar amount of other transition metal oxides, and is due to hopping between localized states. The optical absorption measurements show that the fundamental absorption edge is a function of glass composition and the optical absorption is due to forbidden indirect transitions. From the infra-red absorption spectra, it is found that the addition of transition metal oxides does not introduce any new absorption band in the infra-red spectrum of germanium tellurite glasses. A small shift of existing absorptions toward higher wave number is observed. The ESR measurements revealed that some transition metal ions are diamagnetic while others are paramagnetic in the glass network. (author)

  9. Structural-chemical characteristics of implanted metals

    International Nuclear Information System (INIS)

    Kozejkin, B.V.; Pavlov, P.V.; Pitirimova, E.A.; Frolov, A.I.

    1988-01-01

    Corrosion and structural characteristics of metallic layers implanted by ions of chemically active impurities and noble gases are studied. Dependence of experimental results on parameters of initial materials and technological conditions of implantation is established. In studying corrosion characteristics of implanted metals a strong dependence of chemical passivation effect on technological conditions of ion-implantation and structure of initial material is stated. On the basis of developed mathematical model of chemical passivation effect it is shown that increase of corrosion characteristics of implanted metals is defined by superposition of surface and volumetric mechanisms

  10. Electroconvulsive therapy after maxillofacial metallic implants.

    Science.gov (United States)

    Freeman, G Mark; Perry, Matthew T; Manatt, George S; Cristancho, Pilar

    2014-03-01

    A growing body of literature suggests that electroconvulsive therapy (ECT) can be safely utilized in patients with craniofacial metallic implants. Here we provide radiographic images and the clinical course of a 49-year-old woman with both maxillary and mandibular metallic implants who safely received ECT.

  11. Modification of metallic corrosion by ion implantation

    International Nuclear Information System (INIS)

    Clayton, C.R.

    1981-01-01

    This review will consider some of the properties of surface alloys, formed by ion implantation, which are effective in modifying corrosion behaviour. Examples will be given of the modification of the corrosion behaviour of pure metals, steels and other engineering alloys, resulting from implantation with metals and metalloids. Emphasis will be given to the modification of anodic processes produced by ion implantation since a review will be given elsewhere in the proceedings concerning the modification of cathodic processes. (orig.)

  12. Metal ion implantation: Conventional versus immersion

    International Nuclear Information System (INIS)

    Brown, I.G.; Anders, A.; Anders, S.; Dickinson, M.R.; MacGill, R.A.

    1994-01-01

    Vacuum-arc-produced metal plasma can be used as the ion feedstock material in an ion source for doing conventional metal ion implantation, or as the immersing plasma for doing plasma immersion ion implantation. The basic plasma production method is the same in both cases; it is simple and efficient and can be used with a wide range of metals. Vacuum arc ion sources of different kinds have been developed by the authors and others and their suitability as a metal ion implantation tool has been well established. Metal plasma immersion surface processing is an emerging tool whose characteristics and applications are the subject of present research. There are a number of differences between the two techniques, both in the procedures used and in the modified surfaces created. For example, the condensibility of metal plasma results in thin film formation and subsequent energetic implantation is thus done through the deposited layer; in the usual scenario, this recoil implantation and the intermixing it produces is a feature of metal plasma immersion but not of conventional energetic ion implantation. Metal plasma immersion is more suited (but not limited) to higher doses (>10 17 cm -2 ) and lower energies (E i < tens of keV) than the usual ranges of conventional metal ion implantation. These and other differences provide these vacuum-arc-based surface modification tools with a versatility that enhances the overall technological attractiveness of both

  13. An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to investigate the feasibility of fabricating a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate...

  14. An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to fabricate a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate a suitably-doped active layer...

  15. Additive manufacturing technologies of porous metal implants

    Directory of Open Access Journals (Sweden)

    Yang Quanzhan

    2014-06-01

    Full Text Available Biomedical metal materials with good corrosion resistance and mechanical properties are widely used in orthopedic surgery and dental implant materials, but they can easily cause stress shielding due to the significant difference in elastic modulus between the implant and human bones. The elastic modulus of porous metals is lower than that of dense metals. Therefore, it is possible to adjust the pore parameters to make the elastic modulus of porous metals match or be comparable with that of the bone tissue. At the same time, the open porous metals with pores connected to each other could provide the structural condition for bone ingrowth, which is helpful in strengthening the biological combination of bone tissue with the implants. Therefore, the preparation technologies of porous metal implants and related research have been drawing more and more attention due to the excellent features of porous metals. Selective laser melting (SLM and electron beam melting technology (EBM are important research fields of additive manufacturing. They have the advantages of directly forming arbitrarily complex shaped metal parts which are suitable for the preparation of porous metal implants with complex shape and fine structure. As new manufacturing technologies, the applications of SLM and EBM for porous metal implants have just begun. This paper aims to understand the technology status of SLM and EBM, the research progress of porous metal implants preparation by using SLM and EBM, and the biological compatibility of the materials, individual design and manufacturing requirements. The existing problems and future research directions for porous metal implants prepared by SLM and EBM methods are discussed in the last paragraph.

  16. Surface modification of metals by ion implantation

    International Nuclear Information System (INIS)

    Iwaki, Masaya

    1988-01-01

    Ion implantation in metals has attracted the attention as a useful technology for the formation of new metastable alloys and compounds in metal surface layers without thermal equilibrium. Current studies of metal surface modification by ion implantation with high fluences have expanded from basic research areas and to industrial applications for the improvement of life time of tools. Many results suggest that the high fluence implantation produces the new surface layers with un-expected microscopic characteristics and macroscopic properties due to implant particles, radiation damage, sputtering, and knock-on doping. In this report, the composition, structure and chemical bonding state in surface layers of iron, iron-based alloy and aluminum sheets implanted with high fluences have been investigated by means of secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Tribological properties such as hardness, friction and wear are introduced. (author)

  17. Particle migration and gap healing around trabecular metal implants

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Zippor, Berit

    2005-01-01

    Bone on-growth and peri-implant migration of polyethylene particles were studied in an experimental setting using trabecular metal and solid metal implants. Cylindrical implants of trabecular tantalum metal and solid titanium alloy implants with a glass bead blasted surface were inserted either i...

  18. Versatile high current metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1992-01-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. (orig)

  19. SO-limited mobility in a germanium inversion channel with non-ideal metal gate

    International Nuclear Information System (INIS)

    Shah, Raheel; De Souza, M.M.

    2008-01-01

    Germanium is an attractive candidate for ultra fast CMOS technology due to its potential for doubling electron mobility and quadrupling hole mobility in comparison to silicon. To maintain the requirements of the International Technology Roadmap for Semiconductors (ITRS), high-κ insulators and metal gates will be required in conjunction with Ge technology. Key issues which will have to be addressed in achieving Ge technology are: trap free insulators, assessment of appropriate crystallographic orientations and the selection of gate metals for the best mobility. In this work mobilities are evaluated for Ge-nMOSFET with two metal gates (Al and TiN) and high-κ (HfO 2 ) insulator. Scattering with bulk phonons, surface roughness and high-κ phonons are taken into account. It is predicted that Al as the gate material on Ge {100} substrate performs 50% better than Ge {111} orientation at a sheet concentration of 1 x 10 13 cm -2 . Surface roughness is likely to be the most damaging mobility degradation mechanism at high fields for Ge {111}

  20. Alleviation of fermi-level pinning effect at metal/germanium interface by the insertion of graphene layers

    International Nuclear Information System (INIS)

    Baek, Seung-heon Chris; Seo, Yu-Jin; Oh, Joong Gun; Albert Park, Min Gyu; Bong, Jae Hoon; Yoon, Seong Jun; Lee, Seok-Hee; Seo, Minsu; Park, Seung-young; Park, Byong-Guk

    2014-01-01

    In this paper, we report the alleviation of the Fermi-level pinning on metal/n-germanium (Ge) contact by the insertion of multiple layers of single-layer graphene (SLG) at the metal/n-Ge interface. A decrease in the Schottky barrier height with an increase in the number of inserted SLG layers was observed, which supports the contention that Fermi-level pinning at metal/n-Ge contact originates from the metal-induced gap states at the metal/n-Ge interface. The modulation of Schottky barrier height by varying the number of inserted SLG layers (m) can bring about the use of Ge as the next-generation complementary metal-oxide-semiconductor material. Furthermore, the inserted SLG layers can be used as the tunnel barrier for spin injection into Ge substrate for spin-based transistors.

  1. Poly-Si gate engineering for advanced CMOS transistors by germanium implantation

    International Nuclear Information System (INIS)

    Bourdon, H.; Juhel, M.; Oudet, B.; Breil, N.; Lenoble, D.

    2005-01-01

    Standard gate materials are compared to Ge implanted poly-Si and deposited poly-SiGe. It is demonstrated in this paper that the electrical resistance of the gate is significantly reduced via the use of poly-SiGe (from 30% to 40% decrease in resistance). Similarly, we show via specific optimization that localized Ge implantation is also suitable to reduce gate resistance. Physical characterizations are performed to determine the 'root' causes at the origin of these improvements. In line with future publications showing strong benefits on CMOS device performance, grain size effects seem to be the main mechanisms explaining the measured improvement

  2. The surface blistering kinetics and the H-platelet evolution in H-implanted germanium

    International Nuclear Information System (INIS)

    Yang Fan; Zhang Xuanxiong; Ye Tianchun; Zhuang Songlin

    2012-01-01

    The surface blistering phenomenon produced in H-implanted Ge by a series of low temperature annealing processes was investigated. The kinetic plot of the onset of blistering contains a break point that separates the straight-line plot into two parts, with two distinct slopes based on the calculated activation energy from the different temperature regions for 3×10 16 cm -2 and 5×10 16 cm -2 H-implanted doses. This plot indicates the existence of distinct, temperature dependent mechanisms, probably caused by the release of different types of H-platelets. The turning direction (from low to high temperature) of the Arrhenius plot with the break point is contrary to that of other known materials. The formation and evolution of the H-platelets under the Ge surface was revealed by TEM (transmission electron microscopy). The TEM results demonstrate that the 〈0 0 1〉 platelets parallel to the sample surface are first produced by a low H implantation dose; however, the vertical 〈0 1 0〉 platelets perpendicular to the sample surface form later as the H implantation dose increases. The H-platelets combine with each other, becoming micro-cracks. The {1 1 1} and {3 1 1} micro-cracks serve as interconnections between the 〈0 0 1〉-oriented micro-cracks below the substrate surface. Finally, the accumulated H 2 pressure in the cracks deforms the surface to generate Ge surface exfoliation.

  3. Metallic implants and exposure to radiofrequency radiation

    International Nuclear Information System (INIS)

    Joyner, K.H.; Fleming, A.H.F.; MacFarlane, I.P.; Hocking, B.

    1988-01-01

    There is increasing use of radiofrequency radiation (RFR) in industry for communications, welding, security, radio, medicine, navigation etc. It has been recognised for some years that RFR may interact with cardiac pacemakers and steps have been taken to prevent this interference. It is less well recognised that other metallic implants may also act as antennas in an RFR field and possibly cause adverse health effects by heating local tissues. There are a large and increasing number of implants having metal components which may be found in RFR workers. These implants include artificial joints, rods and plates used in orthopaedics, rings in heart valves, wires in sutures, bionic ears, subcutaneous infusion systems and (external) transdermal drug delivery patches 1 . The physician concerned with job placement of such persons requires information on the likelihood of an implant interacting with RFR so as to impair health. The following outlines the approach developed in Telecom Australia, beginning with the general principles and then presenting a specific example discussion of a specific example

  4. Biomimetic Composite-Metal Hip Resurfacing Implant

    Directory of Open Access Journals (Sweden)

    Habiba Bougherara

    2008-01-01

    Full Text Available Hip resurfacing technique is a conservative arthroplasty used in the young patient in which the femoral head is reshaped to accept metal cap with small guide stem. In the present investigation, a hybrid composite-metal resurfacing implant is proposed. The cup is made of carbon fiber/polyamide 12 (CF/PA12 covered with a thin layer of cobalt chrome (Co-Cr. Finite element (FE method was applied to analyze and compare the biomechanical performances of the hybrid hip resurfacing (HHR and the conventional Birmingham (BHR. Results of the finite element analysis showed that the composite implant leads to an increase in stresses in the cancellous bone by more than 15% than BHR, indicating a lower potential for stress shielding and bone fracture and higher potential for bone apposition with the HHR.

  5. Long range implantation by MEVVA metal ion source

    International Nuclear Information System (INIS)

    Zhang Tonghe; Wu Yuguang; Ma Furong; Liang Hong

    2001-01-01

    Metal vapor vacuum arc (MEVVA) source ion implantation is a new technology used for achieving long range ion implantation. It is very important for research and application of the ion beam modification of materials. The results show that the implanted atom diffusion coefficient increases in Mo implanted Al with high ion flux and high dose. The implanted depth is 311.6 times greater than that of the corresponding ion range. The ion species, doses and ion fluxes play an important part in the long-range implantation. Especially, thermal atom chemistry have specific effect on the long-range implantation during high ion flux implantation at transient high target temperature

  6. The effect of metallic implants on radiation therapy in spinal tumor patients with metallic spinal implants.

    Science.gov (United States)

    Son, Seok Hyun; Kang, Young Nam; Ryu, Mi-Ryeong

    2012-01-01

    The aim of this study was to evaluate the effect of metallic implants on the dose calculation for radiation therapy in patients with metallic implants and to find a way to reduce the error of dose calculation. We made a phantom in which titanium implants were inserted into positions similar to the implant positions in spinal posterior/posterolateral fusion. We compared the calculated dose of the treatment planning systems with the measured dose in the treatment equipment. We used 3 kinds of computed tomography (CT) (kilovoltage CT, extended-scaled kilovoltage CT, and megavoltage CT) and 3 kinds of treatment equipment (ARTISTE, TomoTherapy Hi-Art, and Cyberknife). For measurement of doses, we used an ionization chamber and Gafchromic external beam therapy film. The absolute doses that were measured using an ionization chamber at the isocenter in the titanium phantom were on average 1.9% lower than those in the reference phantom (p = 0.002). There was no statistically significant difference according to the kinds of CT images, the treatment equipment, and the size of the targets. As the distance from the surface of the titanium implants became closer, the measured doses tended to decrease (p metallic implants was less in the megavoltage CT than in the kilovoltage CT or the extended-scaled kilovoltage CT. The error caused by the titanium implants was beyond a clinically acceptable range. To reduce the error of dose calculation, we suggest that the megavoltage CT be used for planning. In addition, it is necessary to consider the distance between the titanium implants and the targets or the organs at risk to prescribe the dose for the target and the dose constraint for the organs at risk. Copyright © 2012 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  7. Metallic artifact in MRI after removal of orthopedic implants

    International Nuclear Information System (INIS)

    Bagheri, Mohammad Hadi; Hosseini, Mehrdad Mohammad; Emami, Mohammad Jafar; Foroughi, Amin Aiboulhassani

    2012-01-01

    Objective: The aim of the present study was to evaluate the metallic artifacts in MRI of the orthopedic patients after removal of metallic implants. Subjects and methods: From March to August 2009, 40 orthopedic patients operated for removal of orthopedic metallic implants were studied by post-operative MRI from the site of removal of implants. A grading scale of 0–3 was assigned for artifact in MR images whereby 0 was considered no artifact; and I–III were considered mild, moderate, and severe metallic artifacts, respectively. These grading records were correlated with other variables including the type, size, number, and composition of metallic devices; and the site and duration of orthopedic devices stay in the body. Results: Metallic susceptibly artifacts were detected in MRI of 18 of 40 cases (45%). Screws and pins in removed hardware were the most important factors for causing artifacts in MRI. The artifacts were found more frequently in the patients who had more screws and pins in the removed implants. Gender, age, site of implantation of the device, length of the hardware, composition of the metallic implants (stainless steel versus titanium), and duration of implantation of the hardware exerted no effect in producing metallic artifacts after removal of implants. Short TE sequences of MRI (such as T1 weighted) showed fewer artifacts. Conclusion: Susceptibility of metallic artifacts is a frequent phenomenon in MRI of patients upon removal of metallic orthopedic implants.

  8. Metallic artifact in MRI after removal of orthopedic implants.

    Science.gov (United States)

    Bagheri, Mohammad Hadi; Hosseini, Mehrdad Mohammad; Emami, Mohammad Jafar; Foroughi, Amin Aiboulhassani

    2012-03-01

    The aim of the present study was to evaluate the metallic artifacts in MRI of the orthopedic patients after removal of metallic implants. From March to August 2009, 40 orthopedic patients operated for removal of orthopedic metallic implants were studied by post-operative MRI from the site of removal of implants. A grading scale of 0-3 was assigned for artifact in MR images whereby 0 was considered no artifact; and I-III were considered mild, moderate, and severe metallic artifacts, respectively. These grading records were correlated with other variables including the type, size, number, and composition of metallic devices; and the site and duration of orthopedic devices stay in the body. Metallic susceptibly artifacts were detected in MRI of 18 of 40 cases (45%). Screws and pins in removed hardware were the most important factors for causing artifacts in MRI. The artifacts were found more frequently in the patients who had more screws and pins in the removed implants. Gender, age, site of implantation of the device, length of the hardware, composition of the metallic implants (stainless steel versus titanium), and duration of implantation of the hardware exerted no effect in producing metallic artifacts after removal of implants. Short TE sequences of MRI (such as T1 weighted) showed fewer artifacts. Susceptibility of metallic artifacts is a frequent phenomenon in MRI of patients upon removal of metallic orthopedic implants. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  9. Bioactive glass coatings for orthopedic metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Esteban, Sonia; Saiz, Eduardo; Fujino, Sigheru; Oku, Takeo; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-06-30

    The objective of this work is to develop bioactive glass coatings for metallic orthopedic implants. A new family of glasses in the SiO2-Na2O-K2O-CaO-MgO-P2O5 system has been synthesized and characterized. The glass properties (thermal expansion, softening and transformation temperatures, density and hardness) are in line with the predictions of established empirical models. The optimized firing conditions to fabricate coatings on Ti-based and Co-Cr alloys have been determined and related to the glass properties and the interfacial reactions. Excellent adhesion to alloys has been achieved through the formation of 100-200 nm thick interfacial layers (Ti5Si3 on Ti-based alloys and CrOx on Co-Cr). Finally, glass coatings, approximately 100 mu m thick, have been fabricated onto commercial Ti alloy-based dental implants.

  10. Influence of the disorder in doped germanium changed by compensation on the critical indices of the metal-insulator transition

    International Nuclear Information System (INIS)

    Rentzsch, R.; Reich, Ch.; Ionov, A.N.; Ginodman, V.; Slimak, I.; Fozooni, P.; Lea, M.J.

    1999-01-01

    We present a critical review of the present status of the critical exponent puzzle of the metal-insulator transition of doped semiconductors with the emphasis on the role of meso- and macroscopy inhomogeneity caused by the disorder of acceptors and donors in the crystals. By using the isotopic and engineering and the neutron transmutation doping of germanium we found for low compensations (at K = 1.4 and 12%) that the critical exponents of the localization length and the dielectric constant are nearly ν = 1/2 and ξ = 1, which double for medium compensations (at K = 39 and 54%) to ν 1 and ξ = 2, respectively

  11. Amorphization of metals by ion implantation and ion beam mixing

    International Nuclear Information System (INIS)

    Rauschenbach, B.; Heera, V.

    1988-01-01

    Amorphous metallic systems can be formed either by high-fluence ion implantation of glassforming species or by irradiation of layered metal systems with inert gas ions. Both techniques and experimental examples are presented. Empirical rules are discussed which predict whether a given system can be transformed into an amorphous phase. Influence of temperature, implantation dose and pre-existing crystalline metal composition on amorphization is considered. Examples are given of the implantation induced amorphous structure, recrystallization and formation of quasicrystalline structures. (author)

  12. Strained silicon/silicon germanium heterojunction n-channel metal oxide semiconductor field effect transistors

    International Nuclear Information System (INIS)

    Olsen, Sarah H.

    2002-01-01

    Investigations into the performance of strained silicon/silicon-germanium (Si/SiGe) n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) have been carried out. Theoretical predictions suggest that use of a strained Si/SiGe material system with advanced material properties compared with conventional silicon allows enhanced MOSFET device performance. This study has therefore investigated the practical feasibility of obtaining superior electrical performance using a Si/SiGe material system. The MOSFET devices consisted of a strained Si surface channel and were fabricated on relaxed SiGe material using a reduced thermal budget process in order to preserve the strain. Two batches of strained Si/SiGe devices fabricated on material grown by differing methods have been analysed and both showed good transistor action. A correlation of electrical and physical device data established that the electrical device behaviour was closely related to the SiGe material quality, which differed depending on growth technique. The cross-wafer variation in the electrical performance of the strained Si/SiGe devices was found to be a function of material quality, thus the viability of Si/SiGe MOSFET technology for commercial applications has been addressed. Of particular importance was the finding that large-scale 'cross-hatching' roughness associated with relaxed SiGe alloys led to degradation in the small-scale roughness at the gate oxide interface, which affects electrical device performance. The fabrication of strained Si MOSFET devices on high quality SiGe material thus enabled significant performance gains to be realised compared with conventional Si control devices. In contrast, the performance of devices fabricated on material with severe cross-hatching roughness was found to be diminished by the nanoscale oxide interface roughness. The effect of device processing on SiGe material with differing as-grown roughness has been carried out and compared with the reactions

  13. Artifacts Quantification of Metal Implants in MRI

    Science.gov (United States)

    Vrachnis, I. N.; Vlachopoulos, G. F.; Maris, T. G.; Costaridou, L. I.

    2017-11-01

    The presence of materials with different magnetic properties, such as metal implants, causes distortion of the magnetic field locally, resulting in signal voids and pile ups, i.e. susceptibility artifacts in MRI. Quantitative and unbiased measurement of the artifact is prerequisite for optimization of acquisition parameters. In this study an image gradient based segmentation method is proposed for susceptibility artifact quantification. The method captures abrupt signal alterations by calculation of the image gradient. Then the artifact is quantified in terms of its extent by an automated cross entropy thresholding method as image area percentage. The proposed method for artifact quantification was tested in phantoms containing two orthopedic implants with significantly different magnetic permeabilities. The method was compared against a method proposed in the literature, considered as a reference, demonstrating moderate to good correlation (Spearman’s rho = 0.62 and 0.802 in case of titanium and stainless steel implants). The automated character of the proposed quantification method seems promising towards MRI acquisition parameter optimization.

  14. Ion implantation enhanced metal-Si-metal photodetectors

    Science.gov (United States)

    Sharma, A. K.; Scott, K. A. M.; Brueck, S. R. J.; Zolper, J. C.; Myers, D. R.

    1994-05-01

    The quantum efficiency and frequency response of simple Ni-Si-Ni metal-semiconductor-metal (MSM) photodetectors at long wavelengths are significantly enhanced with a simple, ion-implantation step to create a highly absorbing region approx. 1 micron below the Si surface. The internal quantum efficiency is improved by a factor of approx. 3 at 860 nm (to 64%) and a full factor of ten at 1.06 microns (to 23%) as compared with otherwise identical unimplanted devices. Dark currents are only slightly affected by the implantation process and are as low as 630 pA for a 4.5-micron gap device at 10-V bias. Dramatic improvement in the impulse response is observed, 100 ps vs. 600 ps, also at 10-V bias and 4.5-micron gap, due to the elimination of carrier diffusion tails in the implanted devices. Due to its planar structure, this device is fully VLSI compatible. Potential applications include optical interconnections for local area networks and multi-chip modules.

  15. Wear properties of metal ion implanted 4140 steel

    International Nuclear Information System (INIS)

    Evans, P.J.; Paoloni, F.J.

    1994-01-01

    AISI type 4140 (high tensile) steel has been implanted with tungsten and titanium using a metal vapour vacuum arc ion source. Doses in the range (1-5)x10 16 ionscm -2 were implanted to a depth of approximately 30nm. The relative wear resistance between non-implanted and implanted specimens has been estimated using pin-on-disc and abrasive wear tests. Implantation of titanium decreased the area of wear tracks by a factor of 5 over unimplanted steel. In some cases the steel was also hardened by a liquid carburization treatment before implantation. Abrasion tests revealed a further improvement in wear resistance on this material following ion irradiation. ((orig.))

  16. Nanotubular surface modification of metallic implants via electrochemical anodization technique.

    Science.gov (United States)

    Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

    2014-01-01

    Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility.

  17. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Hussain, Muhammad Mustafa

    2014-01-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  18. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.

    2014-08-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  19. The appearance and effects of metallic implants in CT images

    International Nuclear Information System (INIS)

    Kairn, T.; Crowe, S.B.; Trapp, J.V.; Fogg, P.

    2013-01-01

    The computed tomography (CT) imaging artefacts that metallic medical implants produce in surrounding tissues are usually contoured and over-ridden during radiotherapy treatment planning. In cases where radiotherapy treatment beams unavoidably pass though implants, it is especially important to understand the imaging artefacts that may occur within the implants themselves. This study examines CT images of a set of simple metallic objects, immersed in water, in order to evaluate reliability and variability of CT numbers (Hounsfield units, HUs) within medical implants. Model implants with a range of sizes (heights from 2.2 to 49.6 mm), electron densities (from 2.3 to 7.7 times the electron density of water) and effective atomic numbers (from 3.9 to 9.0 times the effective atomic number of water in a CT X-ray beam) were created by stacking metal coins from several currencies. These 'implants' were CT scanned within a large (31.0 cm across) and a small (12.8 cm across) water phantom. Resulting HU values are as much as 50 % lower than the result of extrapolating standard electron density calibration data (obtained for tissue and bone densities) up to the metal densities and there is a 6 % difference between the results obtained by scanning with 120 and 140 kVp tube potentials. Profiles through the implants show localised cupping artefacts, within the implants, as well as a gradual decline in HU outside the implants that can cause the implants' sizes to be over estimated by 1.3–9.0 mm. These effects are exacerbated when the implants are scanned in the small phantom or at the side of the large phantom, due to reduced pre-hardening of the X-ray beam in these configurations. These results demonstrate the necessity of over-riding the densities of metallic implants, as well as their artefacts in tissue, in order to obtain accurate radiotherapy dose calculations.

  20. The appearance and effects of metallic implants in CT images.

    Science.gov (United States)

    Kairn, T; Crowe, S B; Fogg, P; Trapp, J V

    2013-06-01

    The computed tomography (CT) imaging artefacts that metallic medical implants produce in surrounding tissues are usually contoured and over-ridden during radiotherapy treatment planning. In cases where radiotherapy treatment beams unavoidably pass though implants, it is especially important to understand the imaging artefacts that may occur within the implants themselves. This study examines CT images of a set of simple metallic objects, immersed in water, in order to evaluate reliability and variability of CT numbers (Hounsfield units, HUs) within medical implants. Model implants with a range of sizes (heights from 2.2 to 49.6 mm), electron densities (from 2.3 to 7.7 times the electron density of water) and effective atomic numbers (from 3.9 to 9.0 times the effective atomic number of water in a CT X-ray beam) were created by stacking metal coins from several currencies. These 'implants' were CT scanned within a large (31.0 cm across) and a small (12.8 cm across) water phantom. Resulting HU values are as much as 50 % lower than the result of extrapolating standard electron density calibration data (obtained for tissue and bone densities) up to the metal densities and there is a 6 % difference between the results obtained by scanning with 120 and 140 kVp tube potentials. Profiles through the implants show localised cupping artefacts, within the implants, as well as a gradual decline in HU outside the implants that can cause the implants' sizes to be over estimated by 1.3-9.0 mm. These effects are exacerbated when the implants are scanned in the small phantom or at the side of the large phantom, due to reduced pre-hardening of the X-ray beam in these configurations. These results demonstrate the necessity of over-riding the densities of metallic implants, as well as their artefacts in tissue, in order to obtain accurate radiotherapy dose calculations.

  1. Determination of metallic traces in kidneys, livers, lungs and spleens of rats with metallic implants after a long implantation time.

    Science.gov (United States)

    Rubio, Juan Carlos; Garcia-Alonso, Maria Cristina; Alonso, Concepcion; Alobera, Miguel Angel; Clemente, Celia; Munuera, Luis; Escudero, Maria Lorenza

    2008-01-01

    Metallic transfer from implants does not stop at surrounding tissues, and metallic elements may be transferred by proteins to become lodged in organs far from the implant. This work presents an in vivo study of metallic implant corrosion to measure metallic element accumulation in organs located far from the implant, such as kidneys, livers, lungs and spleens. The studied metallic implant materials were CoCr alloy, Ti, and the experimental alloy MA956 coated with alpha-alumina. The implants were inserted in the hind legs of Wistar rats. Analysis for Co, Cr, Ti and Al metallic traces was performed after a long exposure time of 12 months by Inductively Coupled Plasma (ICP) with Mass Spectrometry (MS). According to the results, the highest Cr and Ti concentrations were detected in spleens. Co is mainly found in kidneys, since this element is eliminated via urine. Cr and Ti traces increased significantly in rat organs after the long implantation time. The organs of rats implanted with the alpha-alumina coated experimental MA956 did not present any variation in Al content after 12 months, which means there was no degradation of the alumina layer surface.

  2. Plasma-implantation-based surface modification of metals with single-implantation mode

    Science.gov (United States)

    Tian, X. B.; Cui, J. T.; Yang, S. Q.; Fu, Ricky K. Y.; Chu, Paul K.

    2004-12-01

    Plasma ion implantation has proven to be an effective surface modification technique. Its biggest advantage is the capability to treat the objects with irregular shapes without complex manipulation of target holder. Many metal materials such as aluminum, stainless steel, tool steel, titanium, magnesium etc, has been treated using this technique to improve their wear-resistance, corrosion-resistance, fatigue-resistance, oxidation-resistance, bio-compatiblity etc. However in order to achieve thicker modified layers, hybrid processes combining plasma ion implantation with other techniques have been frequently employed. In this paper plasma implantation based surface modification of metals using single-implantation mode is reviewed.

  3. New hydrogen donors in germanium

    International Nuclear Information System (INIS)

    Pokotilo, Yu.M.; Petukh, A.N.; Litvinov, V.V.

    2003-01-01

    The electrophysical properties of the n-type conductivity germanium, irradiated through protons, is studied by the volt-farad method. It is shown that the heat treatment of the implanted germanium at the temperature of 200-300 deg C leads to formation of the fast-diffusing second-rate donors. It is established that the diffusion coefficient of the identified donors coincides with the diffusion coefficient of the atomic hydrogen with an account of the capture on the traps. The conclusion is made, that the atomic hydrogen is the second-rate donor center in germanium [ru

  4. Adhesive, abrasive and oxidative wear in ion-implanted metals

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1985-01-01

    Ion implantation is increasingly being used to provide wear resistance in metals and cemented tungsten carbides. Field trials and laboratory tests indicate that the best performance is achieved in mild abrasive wear. This can be understood in terms of the classification of wear modes (adhesive, abrasive, oxidative etc.) introduced by Burwell. Surface hardening and work hardenability are the major properties to be enhanced by ion implantation. The implantation of nitrogen or dual implants of metallic and interstitial species are effective. Recently developed techniques of ion-beam-enhanced deposition of coatings can further improve wear resistance by lessening adhesion and oxidation. In order to support such hard coatings, ion implantation of nitrogen can be used as a preliminary treatment. There is thus emerging a versatile group of related hard vacuum treatments involving intense beams of nitrogen ions for the purpose of tailoring metal surfaces to resist wear. (Auth.)

  5. Metals for bone implants. Part 1. Powder metallurgy and implant rendering.

    Science.gov (United States)

    Andani, Mohsen Taheri; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael J; Elahinia, Mohammad

    2014-10-01

    New metal alloys and metal fabrication strategies are likely to benefit future skeletal implant strategies. These metals and fabrication strategies were looked at from the point of view of standard-of-care implants for the mandible. These implants are used as part of the treatment for segmental resection due to oropharyngeal cancer, injury or correction of deformity due to pathology or congenital defect. The focus of this two-part review is the issues associated with the failure of existing mandibular implants that are due to mismatched material properties. Potential directions for future research are also studied. To mitigate these issues, the use of low-stiffness metallic alloys has been highlighted. To this end, the development, processing and biocompatibility of superelastic NiTi as well as resorbable magnesium-based alloys are discussed. Additionally, engineered porosity is reviewed as it can be an effective way of matching the stiffness of an implant with the surrounding tissue. These porosities and the overall geometry of the implant can be optimized for strain transduction and with a tailored stiffness profile. Rendering patient-specific, site-specific, morphology-specific and function-specific implants can now be achieved using these and other metals with bone-like material properties by additive manufacturing. The biocompatibility of implants prepared from superelastic and resorbable alloys is also reviewed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

    NARCIS (Netherlands)

    Wellenberg, Ruud H. H.; Donders, Johanna C. E.; Kloen, Peter; Beenen, Ludo F. M.; Kleipool, Roeland P.; Maas, Mario; Streekstra, Geert J.

    2017-01-01

    To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel

  7. Corrosion processes of physical vapor deposition-coated metallic implants.

    Science.gov (United States)

    Antunes, Renato Altobelli; de Oliveira, Mara Cristina Lopes

    2009-01-01

    Protecting metallic implants from the harsh environment of physiological fluids is essential to guaranteeing successful long-term use in a patient's body. Chemical degradation may lead to the failure of an implant device in two different ways. First, metal ions may cause inflammatory reactions in the tissues surrounding the implant and, in extreme cases, these reactions may inflict acute pain on the patient and lead to loosening of the device. Therefore, increasing wear strength is beneficial to the performance of the metallic implant. Second, localized corrosion processes contribute to the nucleation of fatigue cracks, and corrosion fatigue is the main reason for the mechanical failure of metallic implants. Common biomedical alloys such as stainless steel, cobalt-chrome alloys, and titanium alloys are prone to at least one of these problems. Vapor-deposited hard coatings act directly to improve corrosion, wear, and fatigue resistances of metallic materials. The effectiveness of the corrosion protection is strongly related to the structure of the physical vapor deposition layer. The aim of this paper is to present a comprehensive review of the correlation between the structure of physical vapor deposition layers and the corrosion properties of metallic implants.

  8. A 60 keV implanter for metals

    International Nuclear Information System (INIS)

    Leutenecker, R.; Ryssel, H.; Zeller, K.-H.; Spoehrle, H.P.

    1985-01-01

    The design and preliminary performance data of a 60 keV high current implanter for the implantation of non-separated ion beams into metals are described. The target chamber accepts samples up to 70 cm in diameter and is equipped with holders to implant ball bearings, axles and other components which have to be rotated during implantation. Samples are mounted on a rugged table which can move up to 35 kg for +-35 cm in the x and y directions. The implanter, including the vacuum system, is completely computer controlled. The ion source is equipped with an oven having a maximum temperature of 1200 0 C and can deliver ion beams of nitrogen as well as different metal ions such as tin and silver with currents up to 10 mA. (Auth.)

  9. Electrical properties of polymer modified by metal ion implantation

    International Nuclear Information System (INIS)

    Wu Yuguang; Zhang Tonghe; Zhang Huixing; Zhang Xiaoji; Deng Zhiwei; Zhou Gu

    2000-01-01

    Polyethylene terephthalate (PET) has been modified by Ag, Cr, Cu and Si ion implantation with a dose range from 1x10 16 to 2x10 17 ions cm -2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been changed after metal ion implantation. The resistivity of implanted PET decreased obviously with an increase of ion dose. When metal ion dose of 2x10 17 cm -2 was selected, the resistivity of PET could be less than 10 Ω cm, but when Si ions are implanted, the resistivity of PET would be up to several hundred Ω cm. The results show that the conductive behavior of a metal ion implanted sample is obviously different from Si implantation one. The changes of the structure and composition have been observed with transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface structure is varying after ion implantation and it is believed that the change would cause the improvement of the conductive properties. The mechanism of electrical conduction will be discussed

  10. Patch testers' opinions regarding diagnostic criteria for metal hypersensitivity reactions to metallic implants

    DEFF Research Database (Denmark)

    Schalock, Peter C; Thyssen, Jacob P

    2013-01-01

    Metal hypersensitivity reactions to implanted devices remain a challenging and controversial topic. Diagnostic criteria and methods are not well delineated.......Metal hypersensitivity reactions to implanted devices remain a challenging and controversial topic. Diagnostic criteria and methods are not well delineated....

  11. Preventing Bacterial Infections using Metal Oxides Nanocoatings on Bone Implant

    Science.gov (United States)

    Duceac, L. D.; Straticiuc, S.; Hanganu, E.; Stafie, L.; Calin, G.; Gavrilescu, S. L.

    2017-06-01

    Nowadays bone implant removal is caused by infection that occurs around it possibly acquired after surgery or during hospitalization. The purpose of this study was to reveal some metal oxides applied as coatings on bone implant thus limiting the usual antibiotics-resistant bacteria colonization. Therefore ZnO, TiO2 and CuO were synthesized and structurally and morphologically analized in order to use them as an alternative antimicrobial agents deposited on bone implant. XRD, SEM, and FTIR characterization techniques were used to identify structure and texture of these nanoscaled metal oxides. These metal oxides nanocoatings on implant surface play a big role in preventing bacterial infection and reducing surgical complications.

  12. Cutaneous and systemic hypersensitivity reactions to metallic implants

    DEFF Research Database (Denmark)

    Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

    2011-01-01

    ) following the insertion of intravascular stents, dental implants, cardiac pacemakers, or implanted gynecologic devices. Despite repeated attempts by researchers and clinicians to further understand this difficult area of medicine, the association between metal sensitivity and cutaneous allergic reactions......Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous......, and vasculitic eruptions may occur. Also, more complex immune reactions may develop around the implants, resulting in pain, inflammation, and loosening. Nickel, cobalt, and chromium are the three most common metals that elicit both cutaneous and extracutaneous allergic reactions from chronic internal exposure...

  13. Wear properties of metal ion implanted 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J. (Applications of Nuclear Physics, Ansto, Private Mail Bag 1, Menai, NSW 2234 (Australia)); Paoloni, F.J. (Department of Electrical and Computer Engineering, University of Wollongong, GPO Box 1144, Wollongong, NSW 2500 (Australia))

    1994-07-01

    AISI type 4140 (high tensile) steel has been implanted with tungsten and titanium using a metal vapour vacuum arc ion source. Doses in the range (1-5)x10[sup 16]ionscm[sup -2] were implanted to a depth of approximately 30nm. The relative wear resistance between non-implanted and implanted specimens has been estimated using pin-on-disc and abrasive wear tests. Implantation of titanium decreased the area of wear tracks by a factor of 5 over unimplanted steel. In some cases the steel was also hardened by a liquid carburization treatment before implantation. Abrasion tests revealed a further improvement in wear resistance on this material following ion irradiation. ((orig.))

  14. Defect-impurity interactions in ion-implanted metals

    International Nuclear Information System (INIS)

    Turos, A.

    1986-01-01

    An overview of defect-impurity interactions in metals is presented. When point defects become mobile they migrate towards the sinks and on the way can be captured by impurity atoms forming stable associations so-called complexes. In some metallic systems complexes can also be formed athermally during ion implantation by trapping point defects already in the collision cascade. An association of a point defect with an impurity atom leads to its displacement from the lattice site. The structure and stability of complexes are strongly temperature dependent. With increasing temperature they dissociate or grow by multiple defect trapping. The appearance of freely migrating point defects at elevated temperatures, due to ion bombardment or thermal annealing, causes via coupling with defect fluxes, important impurity redistribution. Because of the sensitivity of many metal-in-metal implanted systems to radiation damage the understanding of this processes is essential for a proper interpretation of the lattice occupancy measurements and the optimization of implantation conditions. (author)

  15. Analysis of metal ion release from biomedical implants

    Directory of Open Access Journals (Sweden)

    Ivana Dimić

    2013-06-01

    Full Text Available Metallic biomaterials are commonly used for fixation or replacement of damaged bones in the human body due to their good combination of mechanical properties. The disadvantage of metals as implant materials is their susceptibility to corrosion and metal ion release, which can cause serious health problems. In certain concentrations metals and metal ions are toxic and their presence can cause diverse inflammatory reactions, genetic mutations or even cancer. In this paper, different approaches to metal ion release examination, from biometallic materials sample preparation to research results interpretation, will be presented. An overview of the analytical techniques, used for determination of the type and concentration of released ions from implants in simulated biofluids, is also given in the paper.

  16. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  17. Approaches to reducing photon dose calculation errors near metal implants

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jessie Y.; Followill, David S.; Howell, Rebecca M.; Mirkovic, Dragan; Kry, Stephen F., E-mail: sfkry@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and Graduate School of Biomedical Sciences, The University of Texas Health Science Center Houston, Houston, Texas 77030 (United States); Liu, Xinming [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and Graduate School of Biomedical Sciences, The University of Texas Health Science Center Houston, Houston, Texas 77030 (United States); Stingo, Francesco C. [Department of Biostatistics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and Graduate School of Biomedical Sciences, The University of Texas Health Science Center Houston, Houston, Texas 77030 (United States)

    2016-09-15

    Purpose: Dose calculation errors near metal implants are caused by limitations of the dose calculation algorithm in modeling tissue/metal interface effects as well as density assignment errors caused by imaging artifacts. The purpose of this study was to investigate two strategies for reducing dose calculation errors near metal implants: implementation of metal-based energy deposition kernels in the convolution/superposition (C/S) dose calculation method and use of metal artifact reduction methods for computed tomography (CT) imaging. Methods: Both error reduction strategies were investigated using a simple geometric slab phantom with a rectangular metal insert (composed of titanium or Cerrobend), as well as two anthropomorphic phantoms (one with spinal hardware and one with dental fillings), designed to mimic relevant clinical scenarios. To assess the dosimetric impact of metal kernels, the authors implemented titanium and silver kernels in a commercial collapsed cone C/S algorithm. To assess the impact of CT metal artifact reduction methods, the authors performed dose calculations using baseline imaging techniques (uncorrected 120 kVp imaging) and three commercial metal artifact reduction methods: Philips Healthcare’s O-MAR, GE Healthcare’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI with metal artifact reduction software (MARS) applied. For the simple geometric phantom, radiochromic film was used to measure dose upstream and downstream of metal inserts. For the anthropomorphic phantoms, ion chambers and radiochromic film were used to quantify the benefit of the error reduction strategies. Results: Metal kernels did not universally improve accuracy but rather resulted in better accuracy upstream of metal implants and decreased accuracy directly downstream. For the clinical cases (spinal hardware and dental fillings), metal kernels had very little impact on the dose calculation accuracy (<1.0%). Of the commercial CT artifact

  18. Approaches to reducing photon dose calculation errors near metal implants

    International Nuclear Information System (INIS)

    Huang, Jessie Y.; Followill, David S.; Howell, Rebecca M.; Mirkovic, Dragan; Kry, Stephen F.; Liu, Xinming; Stingo, Francesco C.

    2016-01-01

    Purpose: Dose calculation errors near metal implants are caused by limitations of the dose calculation algorithm in modeling tissue/metal interface effects as well as density assignment errors caused by imaging artifacts. The purpose of this study was to investigate two strategies for reducing dose calculation errors near metal implants: implementation of metal-based energy deposition kernels in the convolution/superposition (C/S) dose calculation method and use of metal artifact reduction methods for computed tomography (CT) imaging. Methods: Both error reduction strategies were investigated using a simple geometric slab phantom with a rectangular metal insert (composed of titanium or Cerrobend), as well as two anthropomorphic phantoms (one with spinal hardware and one with dental fillings), designed to mimic relevant clinical scenarios. To assess the dosimetric impact of metal kernels, the authors implemented titanium and silver kernels in a commercial collapsed cone C/S algorithm. To assess the impact of CT metal artifact reduction methods, the authors performed dose calculations using baseline imaging techniques (uncorrected 120 kVp imaging) and three commercial metal artifact reduction methods: Philips Healthcare’s O-MAR, GE Healthcare’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI with metal artifact reduction software (MARS) applied. For the simple geometric phantom, radiochromic film was used to measure dose upstream and downstream of metal inserts. For the anthropomorphic phantoms, ion chambers and radiochromic film were used to quantify the benefit of the error reduction strategies. Results: Metal kernels did not universally improve accuracy but rather resulted in better accuracy upstream of metal implants and decreased accuracy directly downstream. For the clinical cases (spinal hardware and dental fillings), metal kernels had very little impact on the dose calculation accuracy (<1.0%). Of the commercial CT artifact

  19. Ion beam analysis of metal ion implanted surfaces

    International Nuclear Information System (INIS)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T.; Sood, D.K.

    1993-01-01

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs

  20. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P J; Chu, J W; Johnson, E P; Noorman, J T [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D K [Royal Melbourne Inst. of Tech., VIC (Australia)

    1994-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  1. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  2. Fatigue and wear of metalloid-ion-implanted metals

    International Nuclear Information System (INIS)

    Hohmuth, K.; Richter, E.; Rauschenbach, B.; Blochwitz, C.

    1985-01-01

    The effect of metalloid ion implantation on the fatigue behaviour and wear of nickel and two steels has been investigated. These metals were implanted with boron, carbon and nitrogen ions at energies from 30 to 60 keV and with doses from 1 X 10 16 to 1 X 10 18 ions cm -2 at room temperature. The mechanical behaviour of fatigued nickel was studied in push-pull tests at room temperature. Wear measurements were made using a pin-and-disc technique. The surface structure, dislocation arrangement and modification of the implantation profile resulting from mechanical tests on metals which had been implanted with metalloid ions were examined using high voltage electron microscopy, transmission high energy electron diffraction, scanning electron microscopy and Auger electron spectroscopy. It is reported that nitrogen and boron ion implantation improves the fatigue lifetime, changes the number and density of the slip bands and modifies the dislocation arrangements in nickel. The cyclic deformation leads to recrystallization of the boron-ion-induced amorphous structure of nickel and to diffusion of the boron and nitrogen in the direction of the surface. The wear behaviour of steels was improved by implantation of mass-separated ions and by implantation of ions without mass separation. (Auth.)

  3. Application of ion implantation in metals and alloys

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1981-01-01

    Ion implantation first became established as a precise method of introducing dopant elements into semiconductors. It is now appreciated that there may be equally important applications in metallic tools or components with the purpose of improving their resistance to wear, fatigue or corrosion. Nitrogen ions implanted into steels pin dislocations and thereby harden the metal. Some metallic ions such as yttrium reduce the tendency for oxidative wear. There is a fairly good understanding of how both treatments can provide a long-lasting protection that extends to many times the original depth of implantation. Nitrogen implantation also improves the wear resistance of Co-cemented tungsten carbide and of hard chromium electroplated coatings. These treatments have wide application in press tools, molds, dies and other metal-forming tools as well as in a more limited variety of cutting tools. Some striking improvements can be achieved in the corrosion field, but there are economic and technical reasons for concluding that practical applications of ion implantation will be more restricted and specialized in this area. The most promising area is that in which mechanical stress and oxidation coexist. When a metallic species has to be introduced, a promising new development is to bombard a thin coating of the metal at an elevated temperature. Several powerful mechanisms of radiation-enhanced diffusion can bring about a complete intermixing. Examples of how this has been used to produce wear resistant surfaces in titanium are given. Finally, the equipment developed for the large scale application of the ion implantation process in the engineering field is described

  4. Germanium soup

    Science.gov (United States)

    Palmer, Troy A.; Alexay, Christopher C.

    2006-05-01

    This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

  5. Susceptibility of metallic magnesium implants to bacterial biofilm infections.

    Science.gov (United States)

    Rahim, Muhammad Imran; Rohde, Manfred; Rais, Bushra; Seitz, Jan-Marten; Mueller, Peter P

    2016-06-01

    Magnesium alloys have promising mechanical and biological properties as biodegradable medical implant materials for temporary applications during bone healing or as vascular stents. Whereas conventional implants are prone to colonization by treatment resistant microbial biofilms in which bacteria are embedded in a protective matrix, magnesium alloys have been reported to act antibacterial in vitro. To permit a basic assessment of antibacterial properties of implant materials in vivo an economic but robust animal model was established. Subcutaneous magnesium implants were inoculated with bacteria in a mouse model. Contrary to the expectations, bacterial activity was enhanced and prolonged in the presence of magnesium implants. Systemic antibiotic treatments were remarkably ineffective, which is a typical property of bacterial biofilms. Biofilm formation was further supported by electron microscopic analyses that revealed highly dense bacterial populations and evidence for the presence of extracellular matrix material. Bacterial agglomerates could be detected not only on the implant surface but also at a limited distance in the peri-implant tissue. Therefore, precautions may be necessary to minimize risks of metallic magnesium-containing implants in prospective clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1489-1499, 2016. © 2016 Wiley Periodicals, Inc.

  6. Cutaneous and systemic hypersensitivity reactions to metallic implants.

    Science.gov (United States)

    Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

    2011-01-01

    Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous, and vasculitic eruptions may occur. Also, more complex immune reactions may develop around the implants, resulting in pain, inflammation, and loosening. Nickel, cobalt, and chromium are the three most common metals that elicit both cutaneous and extracutaneous allergic reactions from chronic internal exposure. However, other metal ions as well as bone cement components can cause such hypersensitivity reactions. To complicate things, patients may also develop delayed-type hypersensitivity reactions to metals (ie, in-stent restenosis, prosthesis loosening, inflammation, pain, or allergic contact dermatitis) following the insertion of intravascular stents, dental implants, cardiac pacemakers, or implanted gynecologic devices. Despite repeated attempts by researchers and clinicians to further understand this difficult area of medicine, the association between metal sensitivity and cutaneous allergic reactions remains to be fully understood. This review provides an update of the current knowledge in this field and should be valuable to health care providers who manage patients with conditions related to this field.

  7. Comparison of metal concentrations in rat tibia tissues with various metallic implants.

    Science.gov (United States)

    Okazaki, Yoshimitsu; Gotoh, Emiko; Manabe, Takeshi; Kobayashi, Kihei

    2004-12-01

    To compare metal concentrations in tibia tissues with various metallic implants, SUS316L stainless steel, Co-Cr-Mo casting alloy, and Ti-6Al-4V and V-free Ti-15Zr-4Nb-4Ta alloys were implanted into the rat tibia for up to 48 weeks. After the implant was removed from the tibia by decalcification, the tibia tissues near the implant were lyophilized. Then the concentrations of metals in the tibia tissues by microwave acid digestion were determined by inductively coupled plasma-mass spectrometry. Fe concentrations were determined by graphite-furnace atomic absorption spectrometry. The Fe concentration in the tibia tissues with the SUS316L implant was relatively high, and it rapidly increased up to 12 weeks and then decreased thereafter. On the other hand, the Co concentration in the tibia tissues with the Co-Cr-Mo implant was lower, and it increased up to 24 weeks and slightly decreased at 48 weeks. The Ni concentration in the tibia tissues with the SUS316L implant increased up to 6 weeks and then gradually decreased thereafter. The Cr concentration tended to be higher than the Co concentration. This Cr concentration linearly increased up to 12 weeks and then decreased toward 48 weeks in the tibia tissues with the SUS316L or Co-Cr-Mo implant. Minute quantities of Ti, Al and V in the tibia tissues with the Ti-6Al-4V implant were found. The Ti concentration in the tibia tissues with the Ti-15Zr-4Nb-4Ta implant was lower than that in the tibia tissues with the Ti-6Al-4V implant. The Zr, Nb and Ta concentrations were also very low. The Ti-15Zr-4Nb-4Ta alloy with its low metal release in vivo is considered advantageous for long-term implants.

  8. Patch testers' opinions regarding diagnostic criteria for metal hypersensitivity reactions to metallic implants.

    Science.gov (United States)

    Schalock, Peter C; Thyssen, Jacob P

    2013-01-01

    Metal hypersensitivity reactions to implanted devices remain a challenging and controversial topic. Diagnostic criteria and methods are not well delineated. Diagnostic criteria for hypersensitivity reactions after metallic device implantation are evaluated in this study by a multinational group of patch testers using Thyssen's previously published criteria. A total of 119 dermatologists at the 2012 European Contact Dermatitis Society and 2013 American Contact Dermatitis Society meetings answered a survey regarding their opinions on topics relating to metal hypersensitivity. Four major and 5 minor diagnostic criteria emerged. Approximately 80% of respondents found the following criteria useful (major criteria): chronic dermatitis beginning weeks to months after metallic implantation, eruption overlying the metal implant, positive patch test to a metal component of the implant, and complete clearing after removal of the potentially allergenic implant. Minor criteria (metals (eg, lymphocyte transformation test). In the challenging situation such as a symptomatic or failing orthopedic device, applying these 4 major criteria and the 5 supportive minor criteria may be useful for guiding decision making.

  9. Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome

    Science.gov (United States)

    2015-10-01

    Award Number: W81XWH-10-2-0138 TITLE: Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome PRINCIPAL INVESTIGATOR...Immunogenicity to Metals Affects Orthopaedic pla t Outcome 5b. GRANT NUMBER W91ZSQ0135N646 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Nadim James...DISTRIBUTION / AVAILABILITY STATEMENT Approved for public release; distribution unlimited 13. SUPPLEM ENTARY NOTES 14. ABSTRACT The effects of battlefield

  10. Plasma immersion ion implantation for reducing metal ion release

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J. [Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain); Leibniz-Institut fuer Oberflaechenmodifizierung, 04318 Leipzig (Germany); Universidad de Oviedo, Departamento Quimica Fisica y Analitica (Spain); Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain)

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  11. The ion implantation of metals and engineering materials

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1978-01-01

    An entirely new method of metal finishing, by the process of ion implantation, is described. Introduced at first for semiconductor device applications, this method has now been demonstrated to produce major and long-lasting improvements in the durability of material surfaces, as regards both wear and corrosion. The process is distinct from that of ion plating, and it is not a coating technique. After a general description of ion implantation examples are given of its effects on wear behaviour (mostly in steels and cemented carbides) and on corrosion, in a variety of metals and alloys. Its potential for producing decorative finishes is mentioned briefly. The equipment necessary for carrying out ion implantation for engineering applications has now reached the prototype stage, and manufacture of plant for treating a variety of tools and components is about to commence. These developments are outlined. (author)

  12. Germanium and indium

    Science.gov (United States)

    Shanks, W.C. Pat; Kimball, Bryn E.; Tolcin, Amy C.; Guberman, David E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Germanium and indium are two important elements used in electronics devices, flat-panel display screens, light-emitting diodes, night vision devices, optical fiber, optical lens systems, and solar power arrays. Germanium and indium are treated together in this chapter because they have similar technological uses and because both are recovered as byproducts, mainly from copper and zinc sulfides.The world’s total production of germanium in 2011 was estimated to be 118 metric tons. This total comprised germanium recovered from zinc concentrates, from fly ash residues from coal burning, and from recycled material. Worldwide, primary germanium was recovered in Canada from zinc concentrates shipped from the United States; in China from zinc residues and coal from multiple sources in China and elsewhere; in Finland from zinc concentrates from the Democratic Republic of the Congo; and in Russia from coal.World production of indium metal was estimated to be about 723 metric tons in 2011; more than one-half of the total was produced in China. Other leading producers included Belgium, Canada, Japan, and the Republic of Korea. These five countries accounted for nearly 95 percent of primary indium production.Deposit types that contain significant amounts of germanium include volcanogenic massive sulfide (VMS) deposits, sedimentary exhalative (SEDEX) deposits, Mississippi Valley-type (MVT) lead-zinc deposits (including Irish-type zinc-lead deposits), Kipushi-type zinc-lead-copper replacement bodies in carbonate rocks, and coal deposits.More than one-half of the byproduct indium in the world is produced in southern China from VMS and SEDEX deposits, and much of the remainder is produced from zinc concentrates from MVT deposits. The Laochang deposit in Yunnan Province, China, and the VMS deposits of the Murchison greenstone belt in Limpopo Province, South Africa, provide excellent examples of indium-enriched deposits. The SEDEX deposits at Bainiuchang, China (located in

  13. Use of Metallic Endosseous Implants as a Tooth Substitute

    Science.gov (United States)

    1975-11-25

    metallic blades driven into the bone to become an anchor for prosthetic appliances. A complete critical review of the literature on dental implants was...Otto anni di practica col into metodo d’Infibulazione i:,otallica e-ndomn,,cel lare, rfrs;ultati e considerazioni, Riv. Ital. Sto::at. , January, I

  14. Implantation and Stability of Metallic Fiducials Within Pulmonary Lesions

    International Nuclear Information System (INIS)

    Kupelian, Patrick A.; Forbes, Alan; Willoughby, Twyla R. M.S.; Wallace, Karen; Manon, Rafael R.; Meeks, Sanford L.; Herrera, Luis; Johnston, Alan; Herran, Juan J.

    2007-01-01

    Purpose: To report and describe implantation techniques and stability of metallic fiducials in lung lesions to be treated with external beam radiotherapy. Methods and Materials: Patients undergoing radiation therapy for small early-stage lung cancer underwent implantation with small metallic markers. Implantation was either transcutaneous under computed tomographic (CT) or fluoroscopic guidance or transbronchial with the superDimension/Bronchus system (radiofrequency signal-based bronchoscopy guidance related to CT images). Results: Implantation was performed transcutaneously in 15 patients and transbronchially in 8 patients. Pneumothorax occurred with eight of the 15 transcutaneous implants, six of which required chest tube placement. None of the patients who underwent transbronchial implantation developed pneumothorax. Successfully inserted markers were all usable during gated image-guided radiotherapy. Marker stability was determined by observing the variation in gross target volume (GTV) centroid relative to the marker on repeated CT scans. Average three-dimensional variation in the GTV center relative to the marker was 2.6 ± 1.3 (SD) mm, and the largest variation along any anatomic axis for any patient was <5 mm. Average GTV volume decrease during the observation period was 34% ± 23%. Gross tumor volumes do not appear to shrink uniformly about the center of the tumor, but rather the tumor shapes deform substantially throughout treatment. Conclusions: Transbronchial marker placement is less invasive than transcutaneous placement, which is associated with high pneumothorax rates. Although marker geometry can be affected by tumor shrinkage, implanted markers are stable within tumors throughout the treatment duration regardless of implantation method

  15. Treatment of transverse patellar fractures: a comparison between metallic and non-metallic implants.

    Science.gov (United States)

    Heusinkveld, Maarten H G; den Hamer, Anniek; Traa, Willeke A; Oomen, Pim J A; Maffulli, Nicola

    2013-01-01

    Several methods of transverse patellar fixation have been described. This study compares the clinical outcome and the occurrence of complications of various fixation methods. The databases PubMed, Web of Science, Science Direct, Google Scholar and Google were searched. A direct comparison between fixation techniques using mixed or non-metallic implants and metallic K-wire and tension band fixation shows no significant difference in clinical outcome between both groups. Additionally, studies reporting novel operation techniques show good clinical results. Studies describing the treatment of patients using non-metallic or mixed implants are fewer compared with those using metallic fixation. A large variety of clinical scoring systems were used for assessing the results of treatment, which makes direct comparison difficult. More data of fracture treatment using non-metallic or mixed implants is needed to achieve a more balanced comparison.

  16. Cutaneous and systemic hypersensitivity reactions to metallic implants

    DEFF Research Database (Denmark)

    Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

    2011-01-01

    Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous....... However, other metal ions as well as bone cement components can cause such hypersensitivity reactions. To complicate things, patients may also develop delayed-type hypersensitivity reactions to metals (ie, in-stent restenosis, prosthesis loosening, inflammation, pain, or allergic contact dermatitis...

  17. 1/f Fluctuations in ion implanted metal semiconductor contacts

    International Nuclear Information System (INIS)

    Stojanovic, M.; Marjanovic, N.; Radojevic, B.

    1998-01-01

    Ion implanted Metal-Semiconductor contacts is the most widely used structures in electrical devices. Weather complete devices or some parts are of interest, properties of metal-semiconductor junction strongly influence the quality and external characteristic of electronic devices. That is the reason why special attention is paid to the investigation of factor (noise for example) that could influence given junction. Low frequency 1/f fluctuations (noise) are constantly present in metal-semiconductor junction, so measurement of their level as well as the dependence on factors such as temperature must be taken into account in detailed analysis of electrical characteristics of devices such as contact, nuclear detector with surface barrier etc. In this paper we present the results of low frequency noise level measurements on TiN-Ti-Si structures produced by As + ion implantation. (author)

  18. Elementary characterization of Ti metal alloys used in implant dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Catarina A. M. P.; Paschuk, Sergei A.; Rocha, Anna S. S.; Corrêa, Janine Nicolosi [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Deniak, Valeriy [Instituto de Pesquisa Pelé Pequeno Príncipe, Curitiba, PR (Brazil); Camargo, Liliane [Universidade Paranaense, Umuarama, PR (Brazil); Assis, J.T, E-mail: cata-montenegro@bol.com.br, E-mail: spaschuk@gmail.com, E-mail: denyak@gmail.com, E-mail: lili_camargo2@hotmail.com, E-mail: joaquim@iprj.uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil)

    2017-07-01

    The main goal of present work is analytical characterization of standard dental implants broadly used by Brazilian dentists. An ideal biological alloy for dental implants must have very high biocompatibility, which means that such material should not provoke any serious adverse tissue response. Dental implants are generally marketed as commercially pure titanium (TiCP) due to their excellent mechanical and physical properties. However, sometimes other alloys are employed and consequently it is essential to study the chemical elements present in those alloys that could bring prejudice for the health. Present work investigated TiCP metal alloys used for dental implant manufacturing and evaluated the presence of elements. For alloy characterization and identification of elements it was used EDXRF technique. This method allows to perform the qualitative and quantitative analysis of the materials using the spectra of the characteristic X-rays emitted by the elements present in the metal samples. The experimental setup was based on two X- ray tubes, Mini X model with Ag and Au targets and X-123SDD detector (AMPTEK) and a 0.5 mm Cu collimator, developed due to specific sample geometrical and topography characteristics. Obtained results showed that implant alloys are not exactly TiCP but were manufactured using Ti-Al-V alloy, which contained Fe, Ni, Cu and Zn. The presence of such metals as Al and V in all studied samples shows very clear that studied implants were not manufactured from TiCP alloy. Moreover, according to the American Society for Testing and Materials (ASTM), these elements should not be present in TiCP. (author)

  19. Elementary characterization of Ti metal alloys used in implant dentistry

    International Nuclear Information System (INIS)

    Torres, Catarina A. M. P.; Paschuk, Sergei A.; Rocha, Anna S. S.; Corrêa, Janine Nicolosi; Deniak, Valeriy; Camargo, Liliane; Assis, J.T

    2017-01-01

    The main goal of present work is analytical characterization of standard dental implants broadly used by Brazilian dentists. An ideal biological alloy for dental implants must have very high biocompatibility, which means that such material should not provoke any serious adverse tissue response. Dental implants are generally marketed as commercially pure titanium (TiCP) due to their excellent mechanical and physical properties. However, sometimes other alloys are employed and consequently it is essential to study the chemical elements present in those alloys that could bring prejudice for the health. Present work investigated TiCP metal alloys used for dental implant manufacturing and evaluated the presence of elements. For alloy characterization and identification of elements it was used EDXRF technique. This method allows to perform the qualitative and quantitative analysis of the materials using the spectra of the characteristic X-rays emitted by the elements present in the metal samples. The experimental setup was based on two X- ray tubes, Mini X model with Ag and Au targets and X-123SDD detector (AMPTEK) and a 0.5 mm Cu collimator, developed due to specific sample geometrical and topography characteristics. Obtained results showed that implant alloys are not exactly TiCP but were manufactured using Ti-Al-V alloy, which contained Fe, Ni, Cu and Zn. The presence of such metals as Al and V in all studied samples shows very clear that studied implants were not manufactured from TiCP alloy. Moreover, according to the American Society for Testing and Materials (ASTM), these elements should not be present in TiCP. (author)

  20. Low temperature intermediate band metallic behavior in Ti implanted Si

    Energy Technology Data Exchange (ETDEWEB)

    Olea, Javier, E-mail: oleaariza@fis.ucm.es; Pastor, David; Garcia-Hemme, Eric; Garcia-Hernansanz, Rodrigo; Prado, Alvaro del; Martil, Ignacio; Gonzalez-Diaz, German

    2012-08-31

    Si samples implanted with very high Ti doses and subjected to Pulsed-Laser Melting (PLM) have been electrically analyzed in the scope of a two-layer model previously reported based on the Intermediate Band (IB) theory. Conductivity and Hall effect measurements using the van der Pauw technique suggest that the insulator-metal transition takes place for implantation doses in the 10{sup 14}-10{sup 16} cm{sup -2} range. Results of the sample implanted with the 10{sup 16} cm{sup -2} dose show a metallic behavior at low temperature that is explained by the formation of a p-type IB out of the Ti deep levels. This suggests that the IB would be semi-filled, which is essential for IB photovoltaic devices. - Highlights: Black-Right-Pointing-Pointer We fabricated high dose Ti implanted Si samples for intermediate band research. Black-Right-Pointing-Pointer We measured the electronic transport properties in the 7-300 K range. Black-Right-Pointing-Pointer We show an insulator to metallic transition when the intermediate band is formed. Black-Right-Pointing-Pointer The intermediate band is semi-filled and populated by holes. Black-Right-Pointing-Pointer We satisfactorily explain the electrical behavior by an intermediate band model.

  1. Modification of medical metals by ion implantation of copper

    Science.gov (United States)

    Wan, Y. Z.; Xiong, G. Y.; Liang, H.; Raman, S.; He, F.; Huang, Y.

    2007-10-01

    The effect of copper ion implantation on the antibacterial activity, wear performance and corrosion resistance of medical metals including 317 L of stainless steels, pure titanium, and Ti-Al-Nb alloy was studied in this work. The specimens were implanted with copper ions using a MEVVA source ion implanter with ion doses ranging from 0.5 × 10 17 to 4 × 10 17 ions/cm 2 at an energy of 80 keV. The antibacterial effect, wear rate, and inflexion potential were measured as a function of ion dose. The results obtained indicate that copper ion implantation improves the antibacterial effect and wear behaviour for all the three medical materials studied. However, corrosion resistance decreases after ion implantation of copper. Experimental results indicate that the antibacterial property and corrosion resistance should be balanced for medical titanium materials. The marked deteriorated corrosion resistance of 317 L suggests that copper implantation may not be an effective method of improving its antibacterial activity.

  2. Making Sense of Metal Allergy and Hypersensitivity to Metallic Implants in Relation to Hand Surgery.

    Science.gov (United States)

    Christensen, Thomas J; Samant, Shefali A; Shin, Alexander Y

    2017-09-01

    All metals implanted into a biological system undergo some degree of corrosion depending upon its composition. The electrochemical process of corrosion produces free metal ions, which may activate the host's immune system through a variety of mechanisms. Whereas dermal metal hypersensitivity is common, affecting 10% to 15% of the population, the immune reaction from implanted metals is much less common (allergy and hypersensitivity producing a multitude of patient symptoms. Superficial symptoms may be mild to severe forms of dermatitis, urticaria, pruritus, and vasculitis, whereas deep sequelae include metallosis-related pseudotumor, implant loosening, and joint stiffness. Currently, there are clinical tests to evaluate patients for metal hypersensitivity, but there is little agreement regarding the ideal timing and clinical situation prompting the work-up of a patient for a metal allergy or hypersensitivity. An understanding of the epidemiology, etiology, basic science, diagnostic testing, and treatment of patients with suspected metal allergy, as it pertains to the current literature, will aid orthopedic and plastic surgeons of all subspecialties in the management of patients requiring metallic implants. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  3. Relative SHG measurements of metal thin films: Gold, silver, aluminum, cobalt, chromium, germanium, nickel, antimony, titanium, titanium nitride, tungsten, zinc, silicon and indium tin oxide

    Directory of Open Access Journals (Sweden)

    Franklin Che

    Full Text Available We have experimentally measured the surface second-harmonic generation (SHG of sputtered gold, silver, aluminum, zinc, tungsten, copper, titanium, cobalt, nickel, chromium, germanium, antimony, titanium nitride, silicon and indium tin oxide thin films. The second-harmonic response was measured in reflection using a 150 fs p-polarized laser pulse at 1561 nm. We present a clear comparison of the SHG intensity of these films relative to each other. Our measured relative intensities compare favorably with the relative intensities of metals with published data. We also report for the first time to our knowledge the surface SHG intensity of tungsten and antimony relative to that of well known metallic thin films such as gold and silver. Keywords: Surface second-harmonic generation, Nonlinear optics, Metal thin films

  4. Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

    International Nuclear Information System (INIS)

    Salvadori, M.C.; Teixeira, F.S.; Sgubin, L.G.; Cattani, M.; Brown, I.G.

    2014-01-01

    Highlights: • Metal nanoparticles can be produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. • The nanoparticles nucleate near the maximum of the implantation depth profile, that can be estimated by computer simulation using the TRIDYN. • Nanocomposites, obtained by this way, can be produced in different insulator materials. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. • The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted, reaching the percolation threshold. • Excellent agreement was found between the experimental results and the predictions of the theory. - Abstract: There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in

  5. High-performance germanium n+/p junction by nickel-induced dopant activation of implanted phosphorus at low temperature

    International Nuclear Information System (INIS)

    Huang Wei; Lu Chao; Yu Jue; Wei Jiang-Bin; Chen Chao-Wen; Wang Jian-Yuan; Xu Jian-Fang; Li Cheng; Chen Song-Yan; Lai Hong-Kai; Wang Chen; Liu Chun-Li

    2016-01-01

    High-performance Ge n + /p junctions were fabricated at a low formation temperature from 325 °C to 400 °C with a metal(nickel)-induced dopant activation technique. The obtained NiGe electroded Ge n + /p junction has a rectification ratio of 5.6× 10 4 and a forward current of 387 A/cm 2 at −1 V bias. The Ni-based metal-induced dopant activation technique is expected to meet the requirement of the shallow junction of Ge MOSFET. (paper)

  6. Interaction of mobile phones with superficial passive metallic implants

    International Nuclear Information System (INIS)

    Virtanen, H; Huttunen, J; Toropainen, A; Lappalainen, R

    2005-01-01

    The dosimetry of exposure to radiofrequency (RF) electromagnetic (EM) fields of mobile phones is generally based on the specific absorption rate (SAR, W kg -1 ), which is the electromagnetic energy absorbed in the tissues per unit mass and time. In this study, numerical methods and modelling were used to estimate the effect of a passive, metallic (conducting) superficial implant on a mobile phone EM field and especially its absorption in tissues in the near field. Two basic implant models were studied: metallic pins and rings in the surface layers of the human body near the mobile phone. The aim was to find out 'the worst case scenario' with respect to energy absorption by varying different parameters such as implant location, orientation, size and adjacent tissues. Modelling and electromagnetic field calculations were carried out using commercial SEMCAD software based on the FDTD (finite difference time domain) method. The mobile phone was a 900 MHz or 1800 MHz generic phone with a quarter wave monopole antenna. A cylindrical tissue phantom models different curved sections of the human body such as limbs or a head. All the parameters studied (implant size, orientation, location, adjacent tissues and signal frequency) had a major effect on the SAR distribution and in certain cases high local EM fields arose near the implant. The SAR values increased most when the implant was on the skin and had a resonance length or diameter, i.e. about a third of the wavelength in tissues. The local peak SAR values increased even by a factor of 400-700 due to a pin or a ring. These highest values were reached in a limited volume close to the implant surface in almost all the studied cases. In contrast, without the implant the highest SAR values were generally reached on the skin surface. Mass averaged SAR 1g and SAR 10g values increased due to the implant even by a factor of 3 and 2, respectively. However, at typical power levels of mobile phones the enhancement is unlikely to be

  7. Biodegradable Materials and Metallic Implants-A Review.

    Science.gov (United States)

    Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

    2017-09-26

    Recent progress made in biomaterials and their clinical applications is well known. In the last five decades, great advances have been made in the field of biomaterials, including ceramics, glasses, polymers, composites, glass-ceramics and metal alloys. A variety of bioimplants are currently used in either one of the aforesaid forms. Some of these materials are designed to degrade or to be resorbed inside the body rather than removing the implant after its function is served. Many properties such as mechanical properties, non-toxicity, surface modification, degradation rate, biocompatibility, and corrosion rate and scaffold design are taken into consideration. The current review focuses on state-of-the-art biodegradable bioceramics, polymers, metal alloys and a few implants that employ bioresorbable/biodegradable materials. The essential functions, properties and their critical factors are discussed in detail, in addition to their challenges to be overcome.

  8. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    International Nuclear Information System (INIS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-01-01

    The implantation of 1 MeV metal ( 63 Cu + , 107 Ag + , 197 Au + ) and non-metal ( 4 He + , 12 C + ) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 10 13 ions cm −2 , the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated C=C bonds. For fluences around 1 × 10 17 ions cm −2 , the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C 0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C 0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼10 7 Ω/sq has been measured for implantation with metals at doses higher than 5 × 10 16 ions cm −2 , being 10 17 Ω/sq the corresponding sheet resistance for pristine PC

  9. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Resta, V., E-mail: vincenzo.resta@le.infn.it [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Quarta, G. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Farella, I. [Institute for Microelectronics and Microsystems – Unit of Lecce, National Council of Research (IMM/CNR), Lecce I-73100 (Italy); Maruccio, L. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy); Cola, A. [Institute for Microelectronics and Microsystems – Unit of Lecce, National Council of Research (IMM/CNR), Lecce I-73100 (Italy); Calcagnile, L. [Department of Engineering for Innovation, University of Salento, Via Monteroni, Lecce I-73100 (Italy)

    2014-07-15

    The implantation of 1 MeV metal ({sup 63}Cu{sup +}, {sup 107}Ag{sup +}, {sup 197}Au{sup +}) and non-metal ({sup 4}He{sup +}, {sup 12}C{sup +}) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 10{sup 13} ions cm{sup −2}, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated C=C bonds. For fluences around 1 × 10{sup 17} ions cm{sup −2}, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C{sub 0x} clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C{sub 0x} cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼10{sup 7} Ω/sq has been measured for implantation with metals at doses higher than 5 × 10{sup 16} ions cm{sup −2}, being 10{sup 17} Ω/sq the corresponding sheet resistance for pristine PC.

  10. Head and neck imaging with PET and PET/CT: artefacts from dental metallic implants

    International Nuclear Information System (INIS)

    Goerres, Gerhard W.; Hany, Thomas F.; Kamel, Ehab; Schulthess von, Gustav K.; Buck, Alfred

    2002-01-01

    Germanium-68 based attenuation correction (PET Ge68 ) is performed in positron emission tomography (PET) imaging for quantitative measurements. With the recent introduction of combined in-line PET/CT scanners, CT data can be used for attenuation correction. Since dental implants can cause artefacts in CT images, CT-based attenuation correction (PET CT ) may induce artefacts in PET images. The purpose of this study was to evaluate the influence of dental metallic artwork on the quality of PET images by comparing non-corrected images and images attenuation corrected by PET Ge68 and PET CT . Imaging was performed on a novel in-line PET/CT system using a 40-mAs scan for PET CT in 41 consecutive patients with high suspicion of malignant or inflammatory disease. In 17 patients, additional PET Ge68 images were acquired in the same imaging session. Visual analysis of fluorine-18 fluorodeoxyglucose (FDG) distribution in several regions of the head and neck was scored on a 4-point scale in comparison with normal grey matter of the brain in the corresponding PET images. In addition, artefacts adjacent to dental metallic artwork were evaluated. A significant difference in image quality scoring was found only for the lips and the tip of the nose, which appeared darker on non-corrected than on corrected PET images. In 33 patients, artefacts were seen on CT, and in 28 of these patients, artefacts were also seen on PET imaging. In eight patients without implants, artefacts were seen neither on CT nor on PET images. Direct comparison of PET Ge68 and PET CT images showed a different appearance of artefacts in 3 of 17 patients. Malignant lesions were equally well visible using both transmission correction methods. Dental implants, non-removable bridgework etc. can cause artefacts in attenuation-corrected images using either a conventional 68 Ge transmission source or the CT scan obtained with a combined PET/CT camera. We recommend that the non-attenuation-corrected PET images also be

  11. Broad-beam, high current, metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the 'seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs

  12. Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

    International Nuclear Information System (INIS)

    Hart, Alister J; Sandison, Ann; Quinn, Paul; Mosselmans, J Frederick W; Sampson, Barry; Atkinson, Kirk D; Skinner, John A; Goode, Angela; Powell, Jonathan J

    2009-01-01

    Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

  13. Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

    Energy Technology Data Exchange (ETDEWEB)

    Hart, Alister J [Department of Orthopaedic Surgery, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Sandison, Ann [Department of Histopathology, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Quinn, Paul; Mosselmans, J Frederick W [Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0DE (United Kingdom); Sampson, Barry [Department of Clinical Biochemistry, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Atkinson, Kirk D [8 Nuclear Department Defence Academy College of Management and Technology HMS Sultan Military Road Gosport PO12 3BY (United Kingdom); Skinner, John A [Department of Orthopaedics, Royal National Orthopaedic Hospital, HA7 4LP (United Kingdom); Goode, Angela [Dept of Materials, Imperial College London, SW7 2AZ (United Kingdom); Powell, Jonathan J, E-mail: Paul.Quinn@diamond.ac.u [Medical Research Council Human Nutrition Research Centre, Cambridge CB1 9NL (United Kingdom)

    2009-11-15

    Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

  14. Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

    Science.gov (United States)

    Wellenberg, Ruud H H; Donders, Johanna C E; Kloen, Peter; Beenen, Ludo F M; Kleipool, Roeland P; Maas, Mario; Streekstra, Geert J

    2017-08-25

    To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel tibia plate and a titanium intramedullary nail respectively. Virtual monochromatic images were analyzed from 70 to 190 keV. Region-of-interest (ROI), used to determine fluctuations and inaccuracies in CT numbers of soft tissues and bone, were placed in muscle, fat, cortical bone and intramedullary tibia canal. The stainless-steel implant resulted in more pronounced metal artifacts compared to both titanium implants. CT number inaccuracies in 70 keV reference images were minimized at 130, 180 and 190 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Noise, measured as the standard deviation of pixels within a ROI, was minimized at 130, 150 and 140 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Tailoring dual-energy CT protocols using implant specific virtual monochromatic images minimizes fluctuations and inaccuracies in CT numbers in bone and soft tissues compared to non-metal reference scans.

  15. Laws of phase formation in ion-implanted metals

    International Nuclear Information System (INIS)

    Kazdaev, H.R.; Abylkhalykova, R.B.; Skakov, M.K.

    2004-01-01

    Full text: Main laws of ordered structures formation at molybdenum implantation by elements forming phases of introduction (B, C, N, 0, Si, P, S) are discovered in this work. According to them the character of structural and phase transformations in molybdenum at ion implantation is determined not by kinetic parameters of bombarding particles and their chemical activity but by size factor η x/Me (ratio of nuclear radii of introduced elements and atoms of a matrix). At change of its meaning in the certain limits the following can be observed: superstructures formation (η x/Mo x/Mo x/Mo >0.69). In the latter case at the further implantation doze increasing recrystallization of molybdenum monocrystalline layers amorphized during previous bombarding with chemical connection formation takes place, characterized by us as ion-inducted synthesis. The phenomenon discovered on the samples implanted by phosphorus ions. As the result, the high-temperature phase of molybdenum monophosphide MoP having densely situated lattice was synthesized. The complete confirmation of the main laws of structural and phased transformations at ion implantation established by results on molybdenum monocrystals with OCC lattice was achieved at realization of similar researches on the other transitive metal - zirconium which differs from molybdenum according to a number of attributes: a type of an initial lattice structural condition (large scaled polycrystal), presence of interparticle borders and high solubility of atmospheric impurities (nitrogen, carbon, oxygen). The discovered laws have proved to be true also according to ion implanted samples of monocrystal tungsten and polycrystal tantalum

  16. Influence of metallic dental implants and metal artefacts on dose calculation accuracy.

    Science.gov (United States)

    Maerz, Manuel; Koelbl, Oliver; Dobler, Barbara

    2015-03-01

    Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic™ EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques.

  17. Influence of metallic dental implants and metal artefacts on dose calculation accuracy

    International Nuclear Information System (INIS)

    Maerz, Manuel; Koelbl, Oliver; Dobler, Barbara

    2015-01-01

    Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic trademark EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques. (orig.) [de

  18. Metal-oxide-semiconductor devices based on epitaxial germanium-carbon layers grown directly on silicon substrates by ultra-high-vacuum chemical vapor deposition

    Science.gov (United States)

    Kelly, David Quest

    After the integrated circuit was invented in 1959, complementary metal-oxide-semiconductor (CMOS) technology soon became the mainstay of the semiconductor industry. Silicon-based CMOS has dominated logic technologies for decades. During this time, chip performance has grown at an exponential rate at the cost of higher power consumption and increased process complexity. The performance gains have been made possible through scaling down circuit dimensions by improvements in lithography capabilities. Since scaling cannot continue forever, researchers have vigorously pursued new ways of improving the performance of metal-oxide-semiconductor field-effect transistors (MOSFETs) without having to shrink gate lengths and reduce the gate insulator thickness. Strained silicon, with its ability to boost transistor current by improving the channel mobility, is one of the methods that has already found its way into production. Although not yet in production, high-kappa dielectrics have also drawn wide interest in industry since they allow for the reduction of the electrical oxide thickness of the gate stack without having to reduce the physical thickness of the dielectric. Further out on the horizon is the incorporation of high-mobility materials such as germanium (Ge), silicon-germanium (Si1-xGe x), and the III-V semiconductors. Among the high-mobility materials, Ge has drawn the most attention because it has been shown to be compatible with high-kappa dielectrics and to produce high drive currents compared to Si. Among the most difficult challenges for integrating Ge on Si is finding a suitable method for reducing the number of crystal defects. The use of strain-relaxed Si1- xGex buffers has proven successful for reducing the threading dislocation density in Ge epitaxial layers, but questions remain as to the viability of this method in terms of cost and process complexity. This dissertation presents research on thin germanium-carbon (Ge 1-yCy layers on Si for the fabrication

  19. Hypersensitivity reactions to metallic implants-diagnostic algorithm and suggested patch test series for clinical use

    DEFF Research Database (Denmark)

    Schalock, Peter C; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    Cutaneous and systemic hypersensitivity reactions to implanted metals are challenging to evaluate and treat. Although they are uncommon, they do exist, and require appropriate and complete evaluation. This review summarizes the evidence regarding evaluation tools, especially patch and lymphocyte...... transformation tests, for hypersensitivity reactions to implanted metal devices. Patch test evaluation is the gold standard for metal hypersensitivity, although the results may be subjective. Regarding pre-implant testing, those patients with a reported history of metal dermatitis should be evaluated by patch...... testing. Those without a history of dermatitis should not be tested unless considerable concern exists. Regarding post-implant testing, a subset of patients with metal hypersensitivity may develop cutaneous or systemic reactions to implanted metals following implant. For symptomatic patients, a diagnostic...

  20. Failure of total hip implants: metals and metal release in 52 cases

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Lidén, Carola; Søballe, Kjeld

    2014-01-01

    Background . The pathogenesis of total joint replacement failure is multifactorial. One hypothesis suggests that corrosion and wear of alloys result in metal ion release, which may then cause sensitization and even implant failure, owing to the acquired immune reactivity. Objectives . To assess c...

  1. Stereotactic radiotherapy for patients with metallic implants on vertebral body: A dosimetric comparison

    OpenAIRE

    Guzle Adas, Yasemin; Yazici, Omer; Kekilli, Esra; Kiran, Ferat

    2018-01-01

    Objective: Metallic implants have impacts on dose distribution of radiotherapy. Our purpose is evaluating impact of metallic implants with different dose calculation algorithms on dose distribution. Material and Methods: Two patients with metallic implants on vertebral body were included in this study. They were treated with stereotactic radiotherapy. The data of the patients were retrospectively re-calculated with different TPSs and calculation algorithms. Ray-Tracing (Ry-Tc), Mont...

  2. Mathematical filtering minimizes metallic halation of titanium implants in MicroCT images.

    Science.gov (United States)

    Ha, Jee; Osher, Stanley J; Nishimura, Ichiro

    2013-01-01

    Microcomputed tomography (MicroCT) images containing titanium implant suffer from x-rays scattering, artifact and the implant surface is critically affected by metallic halation. To improve the metallic halation artifact, a nonlinear Total Variation denoising algorithm such as Split Bregman algorithm was applied to the digital data set of MicroCT images. This study demonstrated that the use of a mathematical filter could successfully reduce metallic halation, facilitating the osseointegration evaluation at the bone implant interface in the reconstructed images.

  3. The investigation of ZnO:Al2O3/metal composite back reflectors in amorphous silicon germanium thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    Wang Guang-Hong; Zhao Lei; Yan Bao-Jun; Chen Jing-Wei; Wang Ge; Diao Hong-Wei; Wang Wen-Jing

    2013-01-01

    Different aluminum-doped ZnO (AZO)/metal composite thin films,including AZO/Ag/Al,AZO/Ag/nickelchromium alloy (NiCr),and AZO/Ag/NiCr/Al,are utilized as the back reflectors of p-i-n amorphous silicon germanium thin film solar cells.NiCr is used as diffusion barrier layer between Ag and Al to prevent mutual diffusion,which increases the short circuit current density of solar cell.NiCr and NiCr/Al layers are used as protective layers of Ag layer against oxidation and sulfurization,the higher efficiency of solar cell is achieved.The experimental results show that the performance of a-SiGe solar cell with AZO/Ag/NiCr/Al back reflector is best.The initial conversion efficiency is achieved to be 8.05%.

  4. A trabecular metal implant 4 months after placement: clinical-histologic case report.

    Science.gov (United States)

    Spinato, Sergio; Zaffe, Davide; Felice, Pietro; Checchi, Luigi; Wang, Hom-Lay

    2014-02-01

    The aim of this case report was to histologically evaluate the behavior of a trabecular metal (TM) implant composed of titanium and spatial 3-dimensional tantalum (Ta) trabeculae. This study is the first human histologic case report of this implant. A TM implant was placed in a 54-year-old woman exhibiting moderate chronic periodontitis. After periodontal treatment, the implant was inserted under favorable clinical conditions. Patient was not seen for 4 months because of unrelated breast reduction surgery. At the surgical reopening, periimplant inflammation affecting the coronal third of the implant was observed 4 months after implant placement. With patient's consent, the implant was removed for histologic analysis. Histology highlighted a greater amount of bone in close contact with Ta trabeculae than titanium surfaces. The finding of bone formation around the Ta trabeculae suggests that trabecular metal material promotes bone ingrowth for secondary implant stability. Additional evidence is needed to confirm this observation.

  5. Assessing for Cardiotoxicity from Metal-on-Metal Hip Implants with Advanced Multimodality Imaging Techniques.

    Science.gov (United States)

    Berber, Reshid; Abdel-Gadir, Amna; Rosmini, Stefania; Captur, Gabriella; Nordin, Sabrina; Culotta, Veronica; Palla, Luigi; Kellman, Peter; Lloyd, Guy W; Skinner, John A; Moon, James C; Manisty, Charlotte; Hart, Alister J

    2017-11-01

    High failure rates of metal-on-metal (MoM) hip implants prompted regulatory authorities to issue worldwide safety alerts. Circulating cobalt from these implants causes rare but fatal autopsy-diagnosed cardiotoxicity. There is concern that milder cardiotoxicity may be common and underrecognized. Although blood metal ion levels are easily measured and can be used to track local toxicity, there are no noninvasive tests for organ deposition. We sought to detect correlation between blood metal ions and a comprehensive panel of established markers of early cardiotoxicity. Ninety patients were recruited into this prospective single-center blinded study. Patients were divided into 3 age and sex-matched groups according to implant type and whole-blood metal ion levels. Group-A patients had a ceramic-on-ceramic [CoC] bearing; Group B, an MoM bearing and low blood metal ion levels; and Group C, an MoM bearing and high blood metal-ion levels. All patients underwent detailed cardiovascular phenotyping using cardiac magnetic resonance imaging (CMR) with T2*, T1, and extracellular volume mapping; echocardiography; and cardiac blood biomarker sampling. T2* is a novel CMR biomarker of tissue metal loading. Blood cobalt levels differed significantly among groups A, B, and C (mean and standard deviation [SD], 0.17 ± 0.08, 2.47 ± 1.81, and 30.0 ± 29.1 ppb, respectively) and between group A and groups B and C combined. No significant between-group differences were found in the left atrial or ventricle size, ejection fraction (on CMR or echocardiography), T1 or T2* values, extracellular volume, B-type natriuretic peptide level, or troponin level, and all values were within normal ranges. There was no relationship between cobalt levels and ejection fraction (R = 0.022, 95% confidence interval [CI] = -0.185 to 0.229) or T2* values (R = 0.108, 95% CI = -0.105 to 0.312). Using the best available technologies, we did not find that high (but not extreme) blood cobalt and chromium levels

  6. Outcomes of operative treatment of unstable ankle fractures: a comparison of metallic and biodegradable implants.

    Science.gov (United States)

    Noh, Jung Ho; Roh, Young Hak; Yang, Bo Gyu; Kim, Seong Wan; Lee, Jun Suk; Oh, Moo Kyung

    2012-11-21

    Biodegradable implants for internal fixation of ankle fractures may overcome some disadvantages of metallic implants, such as imaging interference and the potential need for additional surgery to remove the implants. The purpose of this study was to evaluate the outcomes after fixation of ankle fractures with biodegradable implants compared with metallic implants. In this prospectively randomized study, 109 subjects with an ankle fracture underwent surgery with metallic (Group I) or biodegradable implants (Group II). Radiographic results were assessed by the criteria of the Klossner classification system and time to bone union. Clinical results were assessed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, Short Musculoskeletal Function Assessment (SMFA) dysfunction index, and the SMFA bother index at three, six, and twelve months after surgery. One hundred and two subjects completed the study. At a mean of 19.7 months, there were no differences in reduction quality between the groups. The mean operative time was 30.2 minutes in Group I and 56.4 minutes in Group II (p implants were inferior to those after fixation with metallic implants in terms of the score on the AOFAS scale and time to bone union. However, the difference in the final AOFAS score between the groups may not be clinically important. The outcomes associated with the use of biodegradable implants for the fixation of isolated lateral malleolar fractures were comparable with those for metallic implants.

  7. Hypersensitivity reactions to metallic implants-diagnostic algorithm and suggested patch test series for clinical use

    DEFF Research Database (Denmark)

    Schalock, Peter C; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    algorithm to guide the selection of screening allergen series for patch testing is provided. At a minimum, an extended baseline screening series and metal screening is necessary. Static and dynamic orthopaedic implants, intravascular stent devices, implanted defibrillators and dental and gynaecological......Cutaneous and systemic hypersensitivity reactions to implanted metals are challenging to evaluate and treat. Although they are uncommon, they do exist, and require appropriate and complete evaluation. This review summarizes the evidence regarding evaluation tools, especially patch and lymphocyte...... transformation tests, for hypersensitivity reactions to implanted metal devices. Patch test evaluation is the gold standard for metal hypersensitivity, although the results may be subjective. Regarding pre-implant testing, those patients with a reported history of metal dermatitis should be evaluated by patch...

  8. Metal artifact reduction image reconstruction algorithm for CT of implanted metal orthopedic devices: a work in progress

    International Nuclear Information System (INIS)

    Liu, Patrick T.; Pavlicek, William P.; Peter, Mary B.; Roberts, Catherine C.; Paden, Robert G.; Spangehl, Mark J.

    2009-01-01

    Despite recent advances in CT technology, metal orthopedic implants continue to cause significant artifacts on many CT exams, often obscuring diagnostic information. We performed this prospective study to evaluate the effectiveness of an experimental metal artifact reduction (MAR) image reconstruction program for CT. We examined image quality on CT exams performed in patients with hip arthroplasties as well as other types of implanted metal orthopedic devices. The exam raw data were reconstructed using two different methods, the standard filtered backprojection (FBP) program and the MAR program. Images were evaluated for quality of the metal-cement-bone interfaces, trabeculae ≤1 cm from the metal, trabeculae 5 cm apart from the metal, streak artifact, and overall soft tissue detail. The Wilcoxon Rank Sum test was used to compare the image scores from the large and small prostheses. Interobserver agreement was calculated. When all patients were grouped together, the MAR images showed mild to moderate improvement over the FBP images. However, when the cases were divided by implant size, the MAR images consistently received higher image quality scores than the FBP images for large metal implants (total hip prostheses). For small metal implants (screws, plates, staples), conversely, the MAR images received lower image quality scores than the FBP images due to blurring artifact. The difference of image scores for the large and small implants was significant (p=0.002). Interobserver agreement was found to be high for all measures of image quality (k>0.9). The experimental MAR reconstruction algorithm significantly improved CT image quality for patients with large metal implants. However, the MAR algorithm introduced blurring artifact that reduced image quality with small metal implants. (orig.)

  9. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    KAUST Repository

    Almuslem, A. S.

    2017-02-14

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  10. Designing biocompatible Ti-based metallic glasses for implant applications

    International Nuclear Information System (INIS)

    Calin, Mariana; Gebert, Annett; Ghinea, Andreea Cosmina; Gostin, Petre Flaviu; Abdi, Somayeh; Mickel, Christine; Eckert, Jürgen

    2013-01-01

    Ti-based metallic glasses show high potential for implant applications; they overcome in several crucial respects their well-established biocompatible crystalline counterparts, e.g. improved corrosion properties, higher fracture strength and wear resistance, increased elastic strain range and lower Young's modulus. However, some of the elements required for glass formation (e.g. Cu, Ni) are harmful for the human body. We critically reviewed the biological safety and glass forming tendency in Ti of 27 elements. This can be used as a basis for the future designing of novel amorphous Ti-based implant alloys entirely free of harmful additions. In this paper, two first alloys were developed: Ti 75 Zr 10 Si 15 and Ti 60 Nb 15 Zr 10 Si 15 . The overheating temperature of the melt before casting can be used as the controlling parameter to produce fully amorphous materials or bcc-Ti-phase reinforced metallic glass nano-composites. The beneficial effect of Nb addition on the glass-formation and amorphous phase stability was assessed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Crystallization and mechanical behavior of ribbons are influenced by the amount and distribution of the nano-scaled bcc phase existing in the as-cast state. Their electrochemical stability in Ringer's solution at 310 K was found to be significantly better than that of commercial Ti-based biomaterials; no indication for pitting corrosion was recorded. Highlights: ► Link between biocompatibility and glass-forming ability of alloying additions in Ti ► Selection of Ti–Zr–Si and Ti–Zr–Nb–Si glass-forming alloys ► Two novel glassy alloys were developed: Ti 75 Zr 10 Si 15 and Ti 60 Nb 15 Zr 10 Si 15. ► Glass-formation, thermal stability, corrosion and mechanical behavior were studied. ► Assessing the suitability for orthopedic applications.

  11. New developments in metal ion implantation by vacuum arc ion sources and metal plasma immersion

    International Nuclear Information System (INIS)

    Brown, I.G.; Anders, A.; Anders, S.

    1996-01-01

    Ion implantation by intense beams of metal ions can be accomplished using the dense metal plasma formed in a vacuum arc discharge embodied either in a vacuum arc ion source or in a metal plasma immersion configuration. In the former case high energy metal ion beams are formed and implantation is done in a more-or-less conventional way, and in the latter case the substrate is immersed in the plasma and repetitively pulse-biased so as to accelerate the ions at the high voltage plasma sheath formed at the substrate. A number of advances have been made in the last few years, both in plasma technology and in the surface modification procedures, that enhance the effectiveness and versatility of the methods, including for example: controlled increase of the in charge states produced; operation in a dual metal-gaseous ion species mode; very large area beam formation; macroparticle filtering; and the development of processing regimes for optimizing adhesion, morphology and structure. These complementary ion processing techniques provide the plasma tools for doing ion surface modification over a very wide parameter regime, from pure ion implantation at energies approaching the MeV level, through ion mixing at energies in the ∼1 to ∼100 keV range, to IBAD-like processing at energies from a few tens of eV to a few keV. Here the authors review the methods, describe a number of recent developments, and outline some of the surface modification applications to which the methods have been put. 54 refs., 9 figs

  12. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    Science.gov (United States)

    Musket, R. G.

    1989-04-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation, and hydrogen embrittlement. In particular, the results of the reviewed studies are (a) uranium hydriding suppressed by implantation of oxygen and carbon, (b) hydrogen gettered in iron and nickel using implantation of titanium, (c) hydriding of titanium catalyzed by implanted palladium, (d) tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and (e) hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals.

  13. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    International Nuclear Information System (INIS)

    Musket, R.G.

    1989-01-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation and hydrogen embrittlement. In particular, the results of the reviewed studies are 1. uranium hydriding suppressed by implantation of oxygen and carbon, 2. hydrogen gettered in iron and nickel using implantation of titanium, 3. hydriding of titanium catalyzed by implanted palladium, 4. tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and 5. hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals. (orig.)

  14. Improved oxidation resistance of group VB refractory metals by Al+ ion implantation

    International Nuclear Information System (INIS)

    Hampikian, J.M.

    1996-01-01

    Aluminum ion implantation of vanadium, niobium, and tantalum improved the metals' oxidation resistances at 500 C and 735 C. Implanted vanadium oxidized only to one-third the extent of unimplanted vanadium when exposed at 500 C to air. The oxidative weight gains of implanted niobium and tantalum proved negligible when measured at 500 C and for times sufficient to fully convert the untreated metals to their pentoxides. At 735 C, implantation of vanadium only slightly retarded its oxidation, while oxidative weight gains of niobium and tantalum were reduced by factors of 3 or more. Implanted niobium exhibited weight gain in direct proportion to oxidation time squared at 735 C. Microstructural examination of the metals implanted with selected fluences of the 180 kV aluminum ions showed the following. The solubility limit of aluminum is extended by implantation, the body centered cubic (bcc) phases being retained to ∼60 at. pct Al in all three metals. The highest fluence investigated, 2.4 x 10 22 ions/m 2 , produced an ∼400-nm layer of VAl 3 beneath the surface of vanadium, and ∼300-nm layers of an amorphous phase containing ∼70 at. pct Al beneath the niobium and tantalum surfaces. All three metals, implanted to this fluence and annealed at 600 C, contained tri-aluminides, intermetallic compounds known for their oxidation resistances. Specimens implanted to this fluence were thus selected for the oxidation measurements

  15. Surface metal standards produced by ion implantation through a removable layer

    International Nuclear Information System (INIS)

    Schueler, B.W.; Granger, C.N.; McCaig, L.; McKinley, J.M.; Metz, J.; Mowat, I.; Reich, D.F.; Smith, S.; Stevie, F.A.; Yang, M.H.

    2003-01-01

    Surface metal concentration standards were produced by ion implantation and investigated for their suitability to calibrate surface metal measurements by secondary ion mass spectrometry (SIMS). Single isotope implants were made through a 100 nm oxide layer on silicon. The implant energies were chosen to place the peak of the implanted species at a depth of 100 nm. Subsequent removal of the oxide layer was used to expose the implant peak and to produce controlled surface metal concentrations. Surface metal concentration measurements by time-of-flight SIMS (TOF-SIMS) with an analysis depth of 1 nm agreed with the expected surface concentrations of the implant standards with a relative mean standard deviation of 20%. Since the TOF-SIMS relative sensitivity factors (RSFs) were originally derived from surface metal measurements of surface contaminated silicon wafers, the agreement implies that the implant standards can be used to measure RSF values. The homogeneity of the surface metal concentration was typically <10%. The dopant dose remaining in silicon after oxide removal was measured using the surface-SIMS protocol. The measured implant dose agreed with the expected dose with a mean relative standard deviation of 25%

  16. Management of metal-on-metal hip implant patients: Who, when and how to revise?

    Science.gov (United States)

    Berber, Reshid; Skinner, John A; Hart, Alister J

    2016-05-18

    The debate on how best to manage patients with metal-on-metal (MOM) hip implants continues. With over 1 million patients affected worldwide, the impact is far reaching. The majority of the aggressive failures of MOM hip implants have been dealt with by revision hip surgery, leaving patients with a much more indolent pattern of failure of devices that have been in situ for more than 10 years. The longer-term outcome for such patients remains unknown, and much debate exists on how best to manage these patients. Regulatory guidance is available but remains open to interpretation due to the lack of current evidence and long-term studies. Metal ion thresholds for concern have been suggested at 7 ppb for hip resurfacing arthroplasty and below this level for large diameter total hip arthroplasties. Soft tissue changes including pseudotumours and muscle atrophy have been shown to progress, but this is not consistent. New advanced imaging techniques are helping to diagnose complications with metal hips and the reasons for failure, however these are not widely available. This has led to some centres to tackle difficult cases through multidisciplinary collaboration, for both surgical management decisions and also follow-up decisions. We summarise current evidence and consider who is at risk, when revision should be undertaken and how patients should be managed.

  17. Hexagonal undersampling for faster MRI near metallic implants.

    Science.gov (United States)

    Sveinsson, Bragi; Worters, Pauline W; Gold, Garry E; Hargreaves, Brian A

    2015-02-01

    Slice encoding for metal artifact correction acquires a three-dimensional image of each excited slice with view-angle tilting to reduce slice and readout direction artifacts respectively, but requires additional imaging time. The purpose of this study was to provide a technique for faster imaging around metallic implants by undersampling k-space. Assuming that areas of slice distortion are localized, hexagonal sampling can reduce imaging time by 50% compared with conventional scans. This work demonstrates this technique by comparisons of fully sampled images with undersampled images, either from simulations from fully acquired data or from data actually undersampled during acquisition, in patients and phantoms. Hexagonal sampling is also shown to be compatible with parallel imaging and partial Fourier acquisitions. Image quality was evaluated using a structural similarity (SSIM) index. Images acquired with hexagonal undersampling had no visible difference in artifact suppression from fully sampled images. The SSIM index indicated high similarity to fully sampled images in all cases. The study demonstrates the ability to reduce scan time by undersampling without compromising image quality. © 2014 Wiley Periodicals, Inc.

  18. Carbon and metal-carbon implantations into tool steels for improved tribological performance

    Science.gov (United States)

    Hirvonen, J.-P.; Harskamp, F.; Torri, P.; Willers, H.; Fusari, A.; Gibson, N.; Haupt, J.

    1997-05-01

    The high-fluence implantation of carbon and dual implantations of metal-metalloid pairs into steels with different microstructures are briefly reviewed. A previously unexamined system, the implantation of Si and C into two kinds of tool steels, M3 and D2, have been studied in terms of microstructure and tribological performance. In both cases ion implantation transfers a surface into an amorphous layer. However, the tribological behavior of these two materials differs remarkably: in the case of ion-implanted M3 a reduction of wear in a steel pin is observed even at high pin loads, whereas in the case of ion-implanted D2 the beneficial effects of ion implantation were limited to the lowest pin load. The importance of an initial phase at the onset of sliding is emphasized and a number of peculiarities observed in ion-implanted M3 steel are discussed.

  19. Mixing implants of differing metallic composition in the treatment of upper-extremity fractures.

    Science.gov (United States)

    Acevedo, Daniel; Loy, Bo Nasmyth; Loy, Bo Nasymuth; Lee, Brian; Omid, Reza; Itamura, John

    2013-09-01

    Mixing implants with differing metallic compositions has been avoided for fear of galvanic corrosion and subsequent failure of the implants and of bone healing. The purpose of this study was to evaluate upper-extremity fractures treated with open reduction and internal fixation with metallic implants that differed in metallic composition placed on the same bone. The authors studied the effects of using both stainless steel and titanium implants on fracture healing, implant failure, and other complications associated with this method of fixation. Their hypothesis was that combining these metals on the same bone would not cause clinically significant nonunions or undo clinical effects from galvanic corrosion. A retrospective review was performed of 17 patients with upper-extremity fractures fixed with metal implants of differing metallic compositions. The primary endpoint was fracture union. Eight clavicles, 2 proximal humeri, 3 distal humeri, 3 olecranons, and 1 glenoid fracture with an average follow-up 10 months were reviewed. All fractures healed. One patient experienced screw backout, which did not affect healing. This study implies that mixing implants with differing metallic compositions on the same bone for the treatment of fractures does not adversely affect bone healing. No evidence existed of corrosion or an increase in complications with this method of treatment. Contrary to prior belief, small modular hand stainless steel plates can be used to assist in reduction of smaller fracture fragments in combination with anatomic titanium plates to obtain anatomic reduction of the fracture without adversely affecting healing. Copyright 2013, SLACK Incorporated.

  20. Germanium geochemistry and mineralogy

    Science.gov (United States)

    Bernstein, L.R.

    1985-01-01

    Germanium is enriched in the following geologic environments: 1. (1) iron meteorites and terrestrial iron-nickel; 2. (2) sulfide ore deposits, particularly those hosted by sedimentary rocks; 3. (3) iron oxide deposits; 4. (4) oxidized zones of Ge-bearing sulfide deposits; 5. (5) pegmatites, greisens, and skarns; and 6. (6) coal and lignitized wood. In silicate melts, Ge is highly siderophile in the presence of native iron-nickel; otherwise, it is highly lithophile. Among silicate minerals, Ge is concentrated in those having less polymerized silicate tetrahedra such as olivine and topaz. In deposits formed from hydrothermal solutions, Ge tends to be enriched mostly in either sulfides or in fluorine-bearing phases; it is thus concentrated both in some hydrothermal sulfide deposits and in pegmatites, greisens, and skarns. In sulfide deposits that formed from solutions having low to moderate sulfur activity, Ge is concentrated in sphalerite in amounts up to 3000 ppm. Sulfide deposits that formed from solutions having higher sulfur activity allowed Ge to either form its own sulfides, particularly with Cu, or to substitute for As, Sn, or other metals in sulfosalts. The Ge in hydrothermal fluids probably derives from enrichment during the fractional crystallization of igneous fluids, or is due to the incorporation of Ge from the country rocks, particularly from those containing organic material. Germanium bonds to lignin-derivative organic compounds that are found in peat and lignite, accounting for its common concentration in coals and related organic material. Germanium is precipitated from water together with iron hydroxide, accounting for its concentration in some sedimentary and supergene iron oxide deposits. It also is able to substitute for Fe in magnetite in a variety of geologic environments. In the oxidized zone of Ge-bearing sulfide deposits, Ge is concentrated in oxides, hydroxides, and hydroxy-sulfates, sometimes forming its own minerals. It is particularly

  1. Pure high dose metal ion implantation using the plasma immersion technique

    International Nuclear Information System (INIS)

    Zhang, T.; Tang, B.Y.; Zeng, Z.M.; Kwok, T.K.; Chu, P.K.; Monteiro, O.R.; Brown, I.G.

    1999-01-01

    High energy implantation of metal ions can be carried out using conventional ion implantation with a mass-selected ion beam in scanned-spot mode by employing a broad-beam approach such as with a vacuum arc ion source, or by utilizing plasma immersion ion implantation with a metal plasma. For many high dose applications, the use of plasma immersion techniques offers a high-rate process, but the formation of a surface film along with the subsurface implanted layer is sometimes a severe or even fatal detriment. We describe here an operating mode of the metal plasma immersion approach by which pure implantation can be obtained. We have demonstrated the technique by carrying out Ti and Ta implantations at energies of about 80 and 120 keV for Ti and Ta, respectively, and doses on the order of 1x10 17 ions/cm 2 . Our experiments show that virtually pure implantation without simultaneous surface deposition can be accomplished. Using proper synchronization of the metal arc and sample voltage pulse, the applied dose that deposits as a film versus the part that is energetically implanted (the deposition-to-implantation ratio) can be precisely controlled.copyright 1999 American Institute of Physics

  2. Establishing contact between cell-laden hydrogels and metallic implants with a biomimetic adhesive for cell therapy supported implants.

    Science.gov (United States)

    Barthes, Julien; Mutschler, Angela; Dollinger, Camille; Gaudinat, Guillaume; Lavalle, Philippe; Le Houerou, Vincent; Brian McGuinness, Garrett; Engin Vrana, Nihal

    2017-12-15

    For in-dwelling implants, controlling the biological interface is a crucial parameter to promote tissue integration and prevent implant failure. For this purpose, one possibility is to facilitate the establishment of the interface with cell-laden hydrogels fixed to the implant. However, for proper functioning, the stability of the hydrogel on the implant should be ensured. Modification of implant surfaces with an adhesive represents a promising strategy to promote the adhesion of a cell-laden hydrogel on an implant. Herein, we developed a peptidic adhesive based on mussel foot protein (L-DOPA-L-lysine) 2 -L-DOPA that can be applied directly on the surface of an implant. At physiological pH, unoxidized (L-DOPA-L-lysine) 2 -L-DOPA was supposed to strongly adhere to metallic surfaces but it only formed a very thin coating (less than 1 nm). Once oxidized at physiological pH, (L-DOPA-L-lysine) 2 -L-DOPA forms an adhesive coating about 20 nm thick. In oxidized conditions, L-lysine can adhere to metallic substrates via electrostatic interaction. Oxidized L-DOPA allows the formation of a coating through self-polymerization and can react with amines so that this adhesive can be used to fix extra-cellular matrix based materials on implant surfaces through the reaction of quinones with amino groups. Hence, a stable interface between a soft gelatin hydrogel and metallic surfaces was achieved and the strength of adhesion was investigated. We have shown that the adhesive is non-cytotoxic to encapsulated cells and enabled the adhesion of gelatin soft hydrogels for 21 days on metallic substrates in liquid conditions. The adhesion properties of this anchoring peptide was quantified by a 180° peeling test with a more than 60% increase in peel strength in the presence of the adhesive. We demonstrated that by using a biomimetic adhesive, for the application of cell-laden hydrogels to metallic implant surfaces, the hydrogel/implant interface can be ensured without relying on the

  3. Muscle atrophy and metal-on-metal hip implants: a serial MRI study of 74 hips.

    Science.gov (United States)

    Berber, Reshid; Khoo, Michael; Cook, Erica; Guppy, Andrew; Hua, Jia; Miles, Jonathan; Carrington, Richard; Skinner, John; Hart, Alister

    2015-06-01

    Muscle atrophy is seen in patients with metal-on-metal (MOM) hip implants, probably because of inflammatory destruction of the musculo-tendon junction. However, like pseudotumors, it is unclear when atrophy occurs and whether it progresses with time. Our objective was to determine whether muscle atrophy associated with MOM hip implants progresses with time. We retrospectively reviewed 74 hips in 56 patients (32 of them women) using serial MRI. Median age was 59 (23-83) years. The median time post-implantation was 83 (35-142) months, and the median interval between scans was 11 months. Hip muscles were scored using the Pfirrmann system. The mean scores for muscle atrophy were compared between the first and second MRI scans. Blood cobalt and chromium concentrations were determined. The median blood cobalt was 6.84 (0.24-90) ppb and median chromium level was 4.42 (0.20-45) ppb. The median Oxford hip score was 34 (5-48). The change in the gluteus minimus mean atrophy score between first and second MRI was 0.12 (p = 0.002). Mean change in the gluteus medius posterior portion (unaffected by surgical approach) was 0.08 (p = 0.01) and mean change in the inferior portion was 0.10 (p = 0.05). Mean pseudotumor grade increased by 0.18 (p = 0.02). Worsening muscle atrophy and worsening pseudotumor grade occur over a 1-year period in a substantial proportion of patients with MOM hip implants. Serial MRI helps to identify those patients who are at risk of developing worsening soft-tissue pathology. These patients should be considered for revision surgery before irreversible muscle destruction occurs.

  4. Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

    OpenAIRE

    Vrana, Nihal E.; Dupret-Bories, Agnes; Chaubaroux, Christophe; Rieger, Elisabeth; Debry, Christian; Vautier, Dominique; Metz-Boutigue, Marie-Helene; Lavalle, Philippe

    2013-01-01

    Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modi...

  5. Growth and characterization of germanium epitaxial film on silicon (001 with germane precursor in metal organic chemical vapour deposition (MOCVD chamber

    Directory of Open Access Journals (Sweden)

    Kwang Hong Lee

    2013-09-01

    Full Text Available The quality of germanium (Ge epitaxial film grown directly on a silicon (Si (001 substrate with 6° off-cut using conventional germane precursor in a metal organic chemical vapour deposition (MOCVD system is studied. The growth sequence consists of several steps at low temperature (LT at 400 °C, intermediate temperature ramp (LT-HT of ∼10 °C/min and high temperature (HT at 600 °C. This is followed by post-growth annealing in hydrogen at temperature ranging from 650 to 825 °C. The Ge epitaxial film of thickness ∼ 1 μm experiences thermally induced tensile strain of 0.11 % with a treading dislocation density (TDD of ∼107/cm2 and the root-mean-square (RMS roughness of ∼ 0.75 nm. The benefit of growing Ge epitaxial film using MOCVD is that the subsequent III-V materials can be grown in-situ without the need of breaking the vacuum hence it is manufacturing worthy.

  6. PIXE microbeam analysis of the metallic debris release around endosseous implants

    International Nuclear Information System (INIS)

    Buso, G.P.; Galassini, S.; Moschini, G.; Passi, P.; Zadro, A.; Uzunov, N.M.; Doyle, B.L.; Rossi, P.; Provencio, P.

    2005-01-01

    The mechanical friction that occurs during the surgical insertion of endosseous implants, both in dentistry and orthopaedics, may cause the detachment of metal debris which are dislodged into the peri-implant tissues and can lead to adverse clinical effects. This phenomenon more likely happens with coated or roughened implants that are the most widely employed. In the present study were studied dental implants screws made of commercially pure titanium and coated using titanium plasma-spray (TPS) technique. The implants were inserted in the tibia of rabbits, and removed 'en bloc' with the surrounding bone after one month. After proper processing and mounting on plastic holders, samples from bones were analysed by EDXRF setup at of National Laboratories of Legnaro, INFN, Italy, and consequently at 3 MeV proton microbeam setup at Sandia National Laboratories. Elemental maps were drawn, showing some occasional presence of metal particles in the peri-implant bone

  7. Ion implantation

    International Nuclear Information System (INIS)

    Dearnaley, Geoffrey

    1975-01-01

    First, ion implantation in semiconductors is discussed: ion penetration, annealing of damage, gettering, ion implanted semiconductor devices, equipement requirements for ion implantation. The importance of channeling for ion implantation is studied. Then, some applications of ion implantation in metals are presented: study of the corrosion of metals and alloys; influence or ion implantation on the surface-friction and wear properties of metals; hyperfine interactions in implanted metals

  8. Combined use of transcranial magnetic stimulation and metal electrode implants: a theoretical assessment of safety considerations

    Science.gov (United States)

    Golestanirad, Laleh; Rouhani, Hossein; Elahi, Behzad; Shahim, Kamal; Chen, Robert; Mosig, Juan R.; Pollo, Claudio; Graham, Simon J.

    2012-12-01

    This paper provides a theoretical assessment of the safety considerations encountered in the simultaneous use of transcranial magnetic stimulation (TMS) and neurological interventions involving implanted metallic electrodes, such as electrocorticography. Metal implants are subject to magnetic forces due to fast alternating magnetic fields produced by the TMS coil. The question of whether the mechanical movement of the implants leads to irreversible damage of brain tissue is addressed by an electromagnetic simulation which quantifies the magnitude of imposed magnetic forces. The assessment is followed by a careful mechanical analysis determining the maximum tolerable force which does not cause irreversible tissue damage. Results of this investigation provide useful information on the range of TMS stimulator output powers which can be safely used in patients having metallic implants. It is shown that conventional TMS applications can be considered safe when applied on patients with typical electrode implants as the induced stress in the brain tissue remains well below the limit of tissue damage.

  9. In vitro color evaluation of esthetic coatings for metallic dental implants and implant prosthetic appliances.

    Science.gov (United States)

    Pecnik, Christina M; Roos, Malgorzata; Muff, Daniel; Spolenak, Ralph; Sailer, Irena

    2015-05-01

    The aim of this study was to characterize the optical properties of newly developed esthetic coatings for metallic implants and components for an improved peri-implant soft tissue appearance. Pig maxillae (n = 6) were used for the in vitro color evaluation of coated and uncoated samples. Three different coating systems (Ti-ZrO(2), Ti-Al-ZrO(2), and Ti-Ag-ZrO(2)) were deposited on titanium substrates, which exhibited different roughness (polished, machined, and sand-blasted) and interference colors (pink, yellow, and white). Spectrophotometric measurements were made of samples below three different mucosa thicknesses (1 mm, 2 mm, and 3 mm) and titanium served as negative control. Color difference ΔE was calculated using ΔL, Δa, and Δb values for each sample (in total 30 samples). ΔE values were significantly above the threshold value of 3.70 for sand-blasted Ti and Ti-ZrO(2) samples when tested below 1 mm thick soft tissue, hence resulted in a dark appearance of the soft tissues. In contrast, Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples showed significant ΔL values below 1 mm, which indicates a brightening of the covering tissue. In general, ΔE values decreased with increasing thickness of the tissue. At 3 mm thick tissue, ΔE values were significantly below 3.70 for Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples. The preferable substrate surface should be machined due increased color brightness, good soft tissue integration and improved adhesion between coating and substrates. Improvement of the optical appearance of the metal was achieved with the coating systems Ti-Al-ZrO(2) and Ti-Ag-ZrO(2). Darkening effects could not be observed for these systems, and partially light brightening of the tissue was observed. Advantageous colors were suggested to be pink and yellow. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Improving Passivation Process of Si Nanocrystals Embedded in SiO2 Using Metal Ion Implantation

    Directory of Open Access Journals (Sweden)

    Jhovani Bornacelli

    2013-01-01

    Full Text Available We studied the photoluminescence (PL of Si nanocrystals (Si-NCs embedded in SiO2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm inside the SiO2 achieving a robust and better protected system. After metal ion implantation (Ag or Au, and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2 and Ar to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  11. Atomic layer deposition to prevent metal transfer from implants: An X-ray fluorescence study

    Energy Technology Data Exchange (ETDEWEB)

    Bilo, Fabjola [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy); Borgese, Laura, E-mail: laura.borgese@unibs.itl [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy); Prost, Josef; Rauwolf, Mirjam; Turyanskaya, Anna; Wobrauschek, Peter; Kregsamer, Peter; Streli, Christina [Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Pazzaglia, Ugo [Dipartimento Specialità Medico Chirurgiche Sc. Radiol. e Sanità Pubblica, University of Brescia, v.le Europa, 11, 25121 Brescia (Italy); Depero, Laura E. [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy)

    2015-12-30

    Highlights: • Co and Cr migrate from bare alloy implant to the surrounding tissue showing a cluster distribution. • Co and Cr migrate from the TiO{sub 2} coated implant to the surrounding tissue showing a decreasing gradient distribution from the alloy surface. • TiO{sub 2} coating layers obtained by ALD on Co–Cr alloy show a barrier effect for the migration of metals. • The thicker the TiO{sub 2} layer deposited by ALD, the lower the metal migration. • The migration of metals from bare alloy toward the surrounding tissue increases with time. This effect is not detected in the coated samples. - Abstract: We show that Atomic Layer Deposition is a suitable coating technique to prevent metal diffusion from medical implants. The metal distribution in animal bone tissue with inserted bare and coated Co–Cr alloys was evaluated by means of micro X-ray fluorescence mapping. In the uncoated implant, the migration of Co and Cr particles from the bare alloy in the biological tissues is observed just after one month and the number of particles significantly increases after two months. In contrast, no metal diffusion was detected in the implant coated with TiO{sub 2}. Instead, a gradient distribution of the metals was found, from the alloy surface going into the tissue. No significant change was detected after two months of aging. As expected, the thicker is the TiO{sub 2} layer, the lower is the metal migration.

  12. RIKEN 200 kV high current implanter for metal surface modification

    International Nuclear Information System (INIS)

    Iwaki, M.; Yoshida, K.; Sakudo, N.

    1985-01-01

    A high current, metal ion implanter was constructed in order to aid the formation of a new metastable surface alloy. This implanter, called a RIKEN 200 kV high current implanter, is a modified Lintott high current machine (Series III), which has the advantages of having its own microwave ion source and an extra target chamber. The microwave discharge ion source without a hot-filament has a comparatively long lifetime because the chloride ions and radicals in a plasma during discharge of metal chlorides might prevent metal to deposit on the inner walls of the discharge chamber by bombarding and chemically cleaning them. An extra target chamber for metal modification is able to control the surface composition by utilizing the sputtering effect of the ion beam during ion implantation. The use of this ion source and the extra target chamber is suggested to be suitable for the production of metallic ions and for the implantation into metals. The case study will be introduced for TI implantation into Fe. (orig.)

  13. Influence of metals on cytokines production in connection with successful implantation therapy in dentistry.

    Science.gov (United States)

    Podzimek, Stepan; Tomka, Milan; Nemeth, Tibor; Himmlova, Lucie; Matucha, Petr; Prochazkova, Jarmila

    2010-01-01

    In most of patients in need of implantation treatment in the oral cavity, implants heal well, nevertheless, there are some individuals, in whom titanium implants fail for reasons, which remain unclear. The aim of our study was to determine if there is a difference between metal influenced IL-1β, IL-4, IL-6, TNF-α and IFN-γ cytokines production in patients with successfully healed implants compared to those, whose implant therapy was unsuccessful. The two study groups included 12 patients with failed dental titanium implants and 9 patients with successfully healed implants. In the subjects, cytokine production was established after lymphocyte cultivation with mercury, nickel and titanium antigens. IL-1β levels were significantly increased in all patients after stimulation with titanium and in patients with accepted implants compared to patients with failed implants after the stimulation with mercury and titanium. Titanium caused significantly increased IL-6 production in all patients. TNF-α and IFN-γ levels were also significantly increased after the stimulation with titanium. Significantly increased TNF-α levels were found in patients with accepted implants as compared to patients with failed implants. Increased production of IL-1β a IL-6 cytokines in reaction to titanium and increased production of TNF-α and IFN-γ cytokines in reaction to mercury, which is very often present in the form of amalgam in the oral cavity of persons in need of implant therapy, can play an important role in immune reactions during implant healing process. In patients with failed titanium implants, decreased production of these cytokines may participate in implant failure.

  14. Analysis of Accumulating Ability of Heavy Metals in Lotus (Nelumbo nucifera) Improved by Ion Implantation

    International Nuclear Information System (INIS)

    Zhang Jianhua; Wang Naiyan; Zhang Fengshou

    2012-01-01

    Heavy metals have seriously contaminated soil and water, and done harm to public health. Academician WANG Naiyan proposed that ion-implantation technique should be exploited for environmental bioremediation by mutating and breeding plants or microbes. By implanting N + into Taikonglian No.1, we have selected and bred two lotus cultivars, Jingguang No.1 and Jingguang No.2. The present study aims at analyzing the feasibility that irradiation can be used for remediation of soil and water from heavy metals. Compared with parent Taikonglian No.1, the uptaking and accumulating ability of heavy metals in two mutated cultivars was obviously improved. So ion implantation technique can indeed be used in bioremediation of heavy metals in soil and water, but it is hard to select and breed a cultivar which can remedy the soil and water from all the heavy metals.

  15. Dose distribution close to metal implants in Gamma Knife Radiosurgery: A Monte Carlo study

    International Nuclear Information System (INIS)

    Cheung, Joel Y.C.; Yu, K.N.; Chan, Josie F.K.; Ho, Robert T.K.; Yu, C.P.

    2003-01-01

    Materials with high atomic numbers favor the occurrence of the photoelectric effect when they are irradiated with gamma rays. Therefore, the photoelectric effects of metal implants within the target regions in Gamma Knife Radiosurgery are worth studying. In the present work, Monte Carlo simulations using EGS4 were employed to investigate the resulting dose enhancements. A dose enhancement as high as 10% was observed close to a platinum implant along the x and y axes, while no significant dose enhancements were observed for silver, stainless steel 301, and titanium ones. A dose enhancement as high as 20% was observed close to the platinum implant along the z axis at the superior position of the metal-phantom interface and was 10% higher for other metal implants

  16. Studies of hyperfine magnetic fields in transition metals by radioactive ion implantation

    International Nuclear Information System (INIS)

    Kawase, Yoichi; Uehara, Shin-ichi; Nasu, Saburo; Ni Xinbo.

    1994-01-01

    In order to investigate hyperfine magnetic fields in transition metals by a time-differential perturbed angular correlation (TDPAC) technique, radioactive probes of 140 Cs obtained by KUR-ISOL have been implanted on transition metals of Fe, Ni and Co. Lamor precessions of 140 Ce used as a probe nucleus have been observed clearly and the hyperfine fields have been determined precisely corresponding to implanted sites in host metal. The irradiation effects caused by implantation have been examined by annealing the irradiated specimen at about 723 K. Some of the Lamor precessions have disappeared by the annealing. Discussions have been made on the occupied sites after implantation and the recovery process of induced damages by annealing. (author)

  17. Depth concentrations of deuterium ions implanted into some pure metals and alloys

    International Nuclear Information System (INIS)

    Didyk, A.Yu.; Wisniewski, R.; Kitowski, K.; Wilczynska, T.; Hofman, A.; Kulikauskas, V.; Shiryaev, A.A.; Zubavichyus, Ya.V.

    2011-01-01

    Pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd alloys (Pd-Ag, Pd-Pt, Pd-Ru, Pd-Rh) were implanted by 25-keV deuterium ions at fluences in the range (1.2-2.3) x 10 22 D + /m 2 . The post-treatment depth distributions of deuterium ions were measured 10 days and three months after the implantation by using Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS). Comparison of the obtained results allowed us to make conclusions about relative stability of deuterium and hydrogen gases in pure metals and diluted Pd alloys. Very high diffusion rates of implanted deuterium ions from V and Pd pure metals and Pd alloys were observed. Small-angle X-ray scattering revealed formation of nanosized defects in implanted corundum and titanium

  18. Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted $^{163}$Ho ions

    CERN Document Server

    Gastaldo, L.; von Seggern, F.; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

    2013-01-01

    For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of $^{163}$Ho using MMCs having the radioactive $^{163}$Ho ions implanted in the absorber. The implantation of $^{163}$Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. In addition an optimized detector design for future $^{163}$Ho experiments is presented.

  19. Germanium content in Polish hard coals

    Directory of Open Access Journals (Sweden)

    Makowska Dorota

    2016-01-01

    Full Text Available Due to the policy of the European Union, it is necessary to search for new sources of scarce raw materials. One of these materials is germanium, listed as a critical element. This semi-metal is widely used in the electronics industry, for example in the production of semiconductors, fibre optics and solar cells. Coal and fly ash from its combustion and gasification for a long time have been considered as a potential source of many critical elements, particularly germanium. The paper presents the results of germanium content determination in the Polish hard coal. 23 coal samples of various coal ranks were analysed. The samples were collected from 15 mines of the Upper Silesian Coal Basin and from one mine of the Lublin Coal Basin. The determination of germanium content was performed with the use of Atomic Absorption Spectrometry with Electrothermal Atomization (GFAAS. The investigation showed that germanium content in the analysed samples was at least twice lower than the average content of this element in the hard coals analysed so far and was in the range of 0.08 ÷ 1.28 mg/kg. Moreover, the content of Ge in the ashes from the studied coals does not exceed 15 mg/kg, which is lower than the average value of Ge content in the coal ashes. The highest content of this element characterizes coals of the Lublin Coal Basin and young coals type 31 from the Vistula region. The results indicate a low utility of the analysed coal ashes as a source of the recovery of germanium. On the basis of the analyses, the lack of the relationship between the content of the element and the ash content in the tested coals was noted. For coals of the Upper Silesian Coal Basin, the relationship between the content of germanium in the ashes and the depth of the seam was observed.

  20. 3D Metal Printing - Additive Manufacturing Technologies for Frameworks of Implant-Borne Fixed Dental Prosthesis.

    Science.gov (United States)

    Revilla León, M; Klemm, I M; García-Arranz, J; Özcan, M

    2017-09-01

    An edentulous patient was rehabilitated with maxillary metal-ceramic and mandibular metal-resin implant-supported fixed dental prosthesis (FDP). Metal frameworks of the FDPs were fabricated using 3D additive manufacturing technologies utilizing selective laser melting (SLM) and electron beam melting (EBM) processes. Both SLM and EBM technologies were employed in combination with computer numerical control (CNC) post-machining at the implant interface. This report highlights the technical and clinical protocol for fabrication of FDPs using SLM and EBM additive technologies. Copyright© 2017 Dennis Barber Ltd.

  1. Study of highly functionalized metal surface treated by plasma ion implantation

    International Nuclear Information System (INIS)

    Ikeyama, Masami; Miyagawa, Soji; Miyagawa, Yoshiko; Nakao, Setsuo; Masuda, Haruho; Saito, Kazuo; Ono, Taizou; Hayashi, Eiji

    2004-01-01

    Technology for processing metal surfaces with hardness, low friction and free from foreign substances was developed with plasma ion implantation. Diamond-like carbon (DLC) coating is a most promising method for realization of hard and smooth metal surface. DLC coating was tested in a metal pipe with 10 mm diameter and 10 cm length by a newly developed plasma ion implantation instrument. The surface coated by DLC was proved to have characteristics equivalent to those prepared with other methods. A computer program simulating a formation process of DLC coating was developed. Experiments for fluorinating the DLC coating surface was performed. (Y. Kazumata)

  2. Adaptation of metal arc plasma source to plasma source ion implantation

    International Nuclear Information System (INIS)

    Shamim, M.M.; Fetherston, R.P.; Conrad, J.R.

    1995-01-01

    In Plasma Source Ion Implantation (PSII) a target is immersed in a plasma and a train of high negative voltage pulses is applied to accelerate ions into the target and to modify the properties in the near surface region. In PSII, until now the authors have been using gaseous species to generate plasmas. However metal ion plasma may be used to modify the surface properties of material for industrial applications. Conventionally the ion implantation of metal ions is performed using beam line accelerators which have complex engineering and high cost. The employment of a metal arc source to PSII has tremendous potential due to its ability to process the conformal surfaces, simple engineering and cost effectiveness. They have installed metal arc source for generation of titanium plasma. Currently, they are investigating the properties of titanium plasma and material behavior of titanium implanted aluminum and 52100 steel. The recent results of this investigation are presented

  3. The germination of germanium

    Science.gov (United States)

    Burdette, Shawn C.; Thornton, Brett F.

    2018-02-01

    Shawn C. Burdette and Brett F. Thornton explore how germanium developed from a missing element in Mendeleev's periodic table to an enabler for the information age, while retaining a nomenclature oddity.

  4. Examining metallic glass formation in LaCe:Nb by ion implantation

    Directory of Open Access Journals (Sweden)

    Sisson Richard

    2017-01-01

    Full Text Available In order to combine niobium (Nb with lanthanum (La and cerium (Ce, Nb ions were deposited within a thin film of these two elements. According to the Hume-Rothery rules, these elements cannot be combined into a traditional crystalline metallic solid. The creation of an amorphous metallic glass consisting of Nb, La, and Ce is then investigated. Amorphous metallic glasses are traditionally made using fast cooling of a solution of molten metals. In this paper, we show the results of an experiment carried out to form a metallic glass by implanting 9 MeV Nb 3+ atoms into a thin film of La and Ce. Prior to implantation, the ion volume distribution is calculated by Monte Carlo simulation using the SRIM tool suite. Using multiple methods of electron microscopy and material characterization, small quantities of amorphous metallic glass are indeed identified.

  5. Industrial applications of ion implantation into metal surfaces

    International Nuclear Information System (INIS)

    Williams, J.M.

    1987-07-01

    The modern materials processing technique, ion implantation, has intriguing and attractive features that stimulate the imaginations of scientists and technologists. Success of the technique for introducing dopants into semiconductors has resulted in a stable and growing infrastructure of capital equipment and skills for use of the technique in the economy. Attention has turned to possible use of ion implantation for modification of nearly all surface related properties of materials - optical, chemical and corrosive, tribological, and several others. This presentation provides an introduction to fundamental aspects of equipment, technique, and materials science of ion implantation. Practical and economic factors pertaining to the technology are discussed. Applications and potential applications are surveyed. There are already available a number of ion-implanted products, including ball-and-roller bearings and races, punches-and-dies, injection screws for plastics molding, etc., of potential interest to the machine tool industry

  6. Osseoconductive and Corrosion-Inhibiting Plasma-Sprayed Calcium Phosphate Coatings for Metallic Medical Implants

    Directory of Open Access Journals (Sweden)

    Robert B. Heimann

    2017-11-01

    Full Text Available During the last several decades, research into bioceramic coatings for medical implants has emerged as a hot topic among materials scientists and clinical practitioners alike. In particular, today, calcium phosphate-based bioceramic materials are ubiquitously used in clinical applications to coat the stems of metallic endoprosthetic hips as well as the surfaces of dental root implants. Such implants frequently consist of titanium alloys, CoCrMo alloy, or austenitic surgical stainless steels, and aim at replacing lost body parts or restoring functions to diseased or damaged tissues of the human body. In addition, besides such inherently corrosion-resistant metals, increasingly, biodegradable metals such as magnesium alloys are being researched for osseosynthetic devices and coronary stents both of which are intended to remain in the human body for only a short time. Biocompatible coatings provide not only vital biological functions by supporting osseoconductivity but may serve also to protect the metallic parts of implants from corrosion in the aggressive metabolic environment. Moreover, the essential properties of hydroxylapatite-based bioceramic coatings including their in vitro alteration in contact with simulated body fluids will be addressed in this current review paper. In addition, a paradigmatic shift is suggested towards the development of transition metal-substituted calcium hexa-orthophosphates with the NaSiCON (Na superionic conductor structure to be used for implant coatings with superior degradation resistance in the corrosive body environment and with pronounced ionic conductivity that might be utilized in novel devices for electrical bone growth stimulation.

  7. High dose, heavy ion implantation into metals: the use of sacrificial surface layers to enhance retention

    International Nuclear Information System (INIS)

    Clapham, L.

    1994-01-01

    While of considerable interest for the production of metallic alloys, high dose, heavy ion implantation is highly problematical, since the process is limited by sputtering effects. Sputtering is less significant, however, for light target materials, such as C and Al. This paper summarizes studies involving the use of light materials (such as C and Al) which act as slowly sputtering ''sacrificial layers'' when deposited on metallic targets prior to heavy ion implantation. The use of C and Al sacrificial coatings has enabled implanted ion retentions of 100% to be obtained in a number of ion-metal target systems, where the retentions in uncoated samples were as low as 20%. Ion implantation invariably leads to mixing at the sacrificial layer-metal target interface. This mixing may be detrimental in certain systems, so it is useful to be able to minimize or remove this mixed region. To achieve this, a number of techniques have been investigated: (1) removal of the mixed region in the latter stages of the implant; (2) using a barrier layer or chemical effects to minimize mixing at the sacrificial layer-metal interface; (3) choosing a sacrificial layer material which forms a mixed region which has desirable properties. The results of these investigations, for a number of different ion-target systems, are outlined in this paper. (orig.)

  8. Fully phase-encoded MRI near metallic implants using ultrashort echo times and broadband excitation.

    Science.gov (United States)

    Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Koch, Kevin M; Reeder, Scott B

    2018-04-01

    To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. An accelerated 3D fully phase-encoded acquisition with broadband excitation and ultrashort echo times is presented, which uses a broadband radiofrequency pulse to excite the entire off-resonance induced by the metallic implant. Furthermore, fully phase-encoded imaging is used to prevent distortions caused by frequency encoding, and to obtain ultrashort echo times for rapidly decaying signal. Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T 1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T 1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T 1 -weighted multi-acquisition with variable resonance image combination selective were performed in phantoms and subjects with metallic knee and hip prostheses. These acquisitions had similar contrast and acquisition efficiency. Accelerated fully phase-encoded acquisitions with ultrashort echo times and broadband excitation can generate distortion free images near metallic implants in clinically feasible acquisition times. Magn Reson Med 79:2156-2163, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Emission Channeling Studies of the Lattice Site of Oversized Alkali Atoms Implanted in Metals

    CERN Multimedia

    2002-01-01

    % IS340 \\\\ \\\\ As alkali atoms have the largest atomic radius of all elements, the determination of their lattice configuration following implantation into metals forms a critical test for the various models predicting the lattice site of implanted impurity atoms. The site determination of these large atoms will especially be a crucial check for the most recent model that relates the substitutional fraction of oversized elements to their solution enthalpy. Recent exploratory $^{213}$Fr and $^{221}$Fr $\\alpha$-emission channeling experiments at ISOLDE-CERN and hyperfine interaction measurements on Fr implanted in Fe gave an indication for anomalously large substitutional fractions. To investigate further the behaviour of Fr and other alkali atoms like Cs and Rb thoroughly, more on-line emission channeling experiments are needed. We propose a number of shifts for each element, where the temperature of the implanted metals will be varied between 50$^\\circ$ and 700$^\\circ$~K. Temperature dependent measurements wi...

  10. The alteration of oxidation and related properties of metals by ion implantation

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1981-01-01

    A review is given of the various ways in which ion implanted additives can affect the thermal oxidation of metals, for example by blocking diffusion paths for ions, by catalytic effects or by altering the plasticity of the oxide. The versatility of the process has already proved useful in the study of oxidation mechanisms. Ways of achieving a long-lasting protection are discussed in relation to the dominant mechanisms of oxidation inhibition. In many practical applications at elevated temperatures oxidation and mechanical stresses co-exist. In steels the process of oxidative wear is important under conditions of poor lubrication and implanted metallic ions have been shown to be effective. In titanium alloys fatigue cracks probably initiate at dislocation sites at which oxidation proceeds most rapidly, and hence the same implanted species can improve both types of behaviour. Successful implantation treatments for fretting fatigue in titanium and a corrosion-erosion problem in steel are described. (orig.)

  11. Influence of implantation of three metallic ions on the mechanical properties of two polymers

    Energy Technology Data Exchange (ETDEWEB)

    Swain, M.V. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Perry, A.J. [Australian National Univ., Canberra, ACT (Australia); Treglio, J.R.

    1996-12-31

    Ion implantation of poly ethylene terephthalate (PET) and polystyrene (PS) with various high energy metallic ions at 70 kV to dose of 3 x 10{sup 16} ions/cm 2 have been made. Measurements of the mechanical properties of the polymers before and after implantation have been made with an ultra microindentation system using both pointed and a small (2 nm) radiused spherical tipped indenter. Significant differences have been observed between the Ti-B dual implanted surfaces and those of the Au and W implanted surfaces. For both the PET and PS the resistance to indenter penetration at very low loads was much greater for the Ti-B dual implanted surfaces. The estimated hardness and modulus versus depth of penetration for both indenters shows that the spherical indenter produces more consistent and less controversial values that are somewhat lower than the optimistic estimates from pointed indenters. 8 refs., 2 fig.

  12. Influence of implantation of three metallic ions on the mechanical properties of two polymers

    Energy Technology Data Exchange (ETDEWEB)

    Swain, M V [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Perry, A J [Australian National Univ., Canberra, ACT (Australia); Treglio, J R

    1997-12-31

    Ion implantation of poly ethylene terephthalate (PET) and polystyrene (PS) with various high energy metallic ions at 70 kV to dose of 3 x 10{sup 16} ions/cm 2 have been made. Measurements of the mechanical properties of the polymers before and after implantation have been made with an ultra microindentation system using both pointed and a small (2 nm) radiused spherical tipped indenter. Significant differences have been observed between the Ti-B dual implanted surfaces and those of the Au and W implanted surfaces. For both the PET and PS the resistance to indenter penetration at very low loads was much greater for the Ti-B dual implanted surfaces. The estimated hardness and modulus versus depth of penetration for both indenters shows that the spherical indenter produces more consistent and less controversial values that are somewhat lower than the optimistic estimates from pointed indenters. 8 refs., 2 fig.

  13. The controlled incorporation of foreign elements in metal surfaces by means of quantitative ion implantation

    International Nuclear Information System (INIS)

    Gries, W.H.

    1977-01-01

    Quantitative ion implantation is a powerful new method for the doping of metal surfaces with accurately known quantities of an element or one of its isotopes. It can be applied for the preparation of standards for various uses in instrumental methods of surface and bulk analysis. This paper provides selected information on some theoretical and practical aspects of quantitative ion implantation with the object of promoting the application of the method and stimulating further purposeful research on the subject. (Auth.)

  14. A preliminary biomechanical study of a novel carbon-fibre hip implant versus standard metallic hip implants.

    Science.gov (United States)

    Bougherara, Habiba; Zdero, Rad; Dubov, Anton; Shah, Suraj; Khurshid, Shaheen; Schemitsch, Emil H

    2011-01-01

    Total hip arthroplasty is a widespread surgical approach for treating severe osteoarthritis of the human hip. Aseptic loosening of standard metallic hip implants due to stress shielding and bone loss has motivated the development of new materials for hip prostheses. Numerically, a three-dimensional finite element (FE) model that mimicked hip implants was used to compare a new hip stem to two commercially available implants. The hip implants simulated were a novel CF/PA12 carbon-fibre polyamide-based composite hip stem, the Exeter hip stem (Stryker, Mahwah, NJ, USA), and the Omnifit Eon (Stryker, Mahwah, NJ, USA). A virtual axial load of 3 kN was applied to the FE model. Strain and stress distributions were computed. Experimentally, the three hip stems had their distal portions rigidly mounted and had strain gauges placed along the surface at 3 medial and 3 lateral locations. Axial loads of 3 kN were applied. Measurements of axial stiffness and strain were taken and compared to FE analysis. The overall linear correlation between FE model versus experimental strains showed reasonable results for the lines-of-best-fit for the Composite (Pearson R(2)=0.69, slope=0.82), Exeter (Pearson R(2)=0.78, slope=0.59), and Omnifit (Pearson R(2)=0.66, slope=0.45), with some divergence for the most distal strain locations. From FE analysis, the von Mises stress range for the Composite stem was much lower than that in the Omnifit and Exeter implants by 200% and 45%, respectively. The preliminary experiments showed that the Composite stem stiffness (1982 N/mm) was lower than the metallic hip stem stiffnesses (Exeter, 2460 N/mm; Omnifit, 2543 N/mm). This is the first assessment of stress, strain, and stiffness of the CF/PA12 carbon-fibre hip stem compared to standard commercially-available devices. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

  15. Surface layers in the 4A group metals with implanted silicon ions

    International Nuclear Information System (INIS)

    Kovneristyj, Yu.K.; Vavilova, V.V.; Krasnopevtsev, V.V.; Galkin, L.N.; Kudyshev, A.N.; Klechkovskaya, V.V.

    1987-01-01

    A study was made on the change of structure and phase composition of fine near the surface layers of 4A group metals (Hf, Zr, Ti) during ion Si implantation and successive thermal annealing at elevated temperatures. Implantation of Si + ions with 30 or 16 keV energy in Ti, Zr and Hf at room temperature results to amorphization of metal surface layer. The surface hafnium and titanium layer with implanted Si atoms due to interaction with residual atmosphere of oxygen turns during annealing at 870 K to amorphous solid solution of HfO 2m or TiO 2 with Si, preventing further metal oxidation; layers of amorphous alloy are characterized by thermal stability up to 1270 K. Oxidation of the surface amorphous layer in residual oxygen atmosphere and its crystallization in ZrO 2 take place in result of Zr annealing with implanted Si ions at temperature not exceeding 870 K. Similar phenomena are observed in the case of hafnium with implanted oxygen ions or small dose of silicon ions. Thermal stability of amorphous layers produced during ion implantation of Si in Ti, Zr and Hf corresponds to scale resistance of monolithic alloys in Ti-Si, Zr-Si and Hf-Si systems

  16. Systemic levels of metallic ions released from orthodontic mini-implants.

    Science.gov (United States)

    de Morais, Liliane Siqueira; Serra, Glaucio Guimarães; Albuquerque Palermo, Elisabete Fernandes; Andrade, Leonardo Rodrigues; Müller, Carlos Alberto; Meyers, Marc André; Elias, Carlos Nelson

    2009-04-01

    Orthodontic mini-implants are a potential source of metallic ions to the human body because of the corrosion of titanium (Ti) alloy in body fluids. The purpose of this study was to gauge the concentration of Ti, aluminum (Al), and vanadium (V), as a function of time, in the kidneys, livers, and lungs of rabbits that had Ti-6Al-4V alloy orthodontic mini-implants placed in their tibia. Twenty-three New Zealand rabbits were randomly divided into 4 groups: control, 1 week, 4 weeks, and 12 weeks. Four orthodontic mini-implants were placed in the left proximal tibia of 18 rabbits. Five control rabbits had no orthodontic mini-implants. After 1, 4, and 12 weeks, the rabbits were killed, and the selected tissues were extracted and prepared for analysis by graphite furnace atomic absorption spectrophotometry. Low amounts of Ti, Al, and V were detectable in the 1-week, 4-weeks, and 12-weeks groups, confirming that release of these metals from the mini-implants occurs, with diffusion and accumulation in remote organs. Despite the tendency of ion release when using the Ti alloy as orthodontic mini-implants, the amounts of metals detected were significantly below the average intake of these elements through food and drink and did not reach toxic concentrations.

  17. Evaluation of marginal fit of single implant-supported metal-ceramic crowns prepared by using presintered metal blocks.

    Science.gov (United States)

    Pasali, Baris; Sarac, Duygu; Kaleli, Necati; Sarac, Yakup Sinasi

    2018-02-01

    Recently, presintered metal blocks for nonprecious and precious metal implant-supported restorations have gained popularity in computer-aided design and computer-aided manufacturing (CAD-CAM) systems. However, few studies have evaluated the marginal discrepancy of implant-supported restorations made with these new alloy systems. The purpose of this in vitro study was to compare the milling-sintering method with the lost-wax and milling methods in terms of the marginal fit of implant-supported metal-ceramic restorations. Thirty implant abutments screwed to implant analogs were embedded into acrylic resin to investigate marginal fit and then divided according to fabrication methods into the following 3 groups (n=10): lost-wax (LW; control group), milling (M), and milling-sintering (MS). Porcelain material was applied to all specimens after completion of the fabrication process. Subsequently, all specimens were cemented to implant abutments for the measurement of marginal discrepancies. Twelve marginal discrepancy measurements were recorded on each implant abutment by using a stereomicroscope. The arithmetic mean of these 12 measurements was considered the mean marginal discrepancy value of each abutment. Data were statistically analyzed by using 1-way ANOVA and Tukey honest significant difference tests (α=.05). The lowest mean marginal discrepancy values (81 ±2 μm) were observed in the M group, which was significantly different (Pmarginal discrepancy values (99 ±2 μm) were observed in the MS group. The results revealed that restorations prepared by the milling-sintering method provided clinically acceptable results (marginal fit. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Reemission and permeation of deuterium implanted into metals

    International Nuclear Information System (INIS)

    Tanabe, T.; Furuyama, Y.; Imoto, S.

    1984-01-01

    Focusing on the marked depression of deuterium permeation rate during the deuteron bombardment, implantation experiments coupled with gaseous permeation experiments are performed on pure Ni and Ni with evaporated MnO. It is concluded that the reemission of implanted deuterium is initially depressed, but it soon becomes enhanced with increase of fluence leading to a rapid decrease of permeation rate at the intermediate temperatures 600-1000 K, which is attributed to the formation of short diffusion paths from the projected range to the front surface. (orig.)

  19. Nanotubular surface modification of metallic implants via electrochemical anodization technique

    OpenAIRE

    Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

    2014-01-01

    Lu-Ning Wang,1 Ming Jin,1 Yudong Zheng,1 Yueping Guan,1 Xin Lu,1 Jing-Li Luo21School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China; 2Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, CanadaAbstract: Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the...

  20. Simplified Technique for Incorporating a Metal Mesh into Record Bases for Mandibular Implant Overdentures.

    Science.gov (United States)

    Godoy, Antonio; Siegel, Sharon C

    2015-12-01

    Mandibular implant-retained overdentures have become the standard of care for patients with mandibular complete edentulism. As part of the treatment, the mandibular implant-retained overdenture may require a metal mesh framework to be incorporated to strengthen the denture and avoid fracture of the prosthesis. Integrating the metal mesh framework as part of the acrylic record base and wax occlusion rim before the jaw relation procedure will avoid the distortion of the record base and will minimize the chances of processing errors. A simplified method to incorporate the mesh into the record base and occlusion rim is presented in this technique article. © 2015 by the American College of Prosthodontists.

  1. Precipitation of lithium in germanium

    International Nuclear Information System (INIS)

    Masaik, M.; Furgolle, B.

    1969-01-01

    The precipitation of Lithium in Germanium was studied. Taking account of the interactions Ga LI, LiO, we calculated the oxygen content in germanium samples from the resistivity measurements. (authors)

  2. Osteogenecity of octacalcium phosphate coatings applied on porous metal implants

    NARCIS (Netherlands)

    Barrère, F.; van der Valk, Chantal M.; Dalmeijer, Remco A.J.; Meijer, Gert; van Blitterswijk, Clemens; de Groot, K.; Layrolle, Pierre

    2003-01-01

    The biomimetic route allows the homogeneous deposition of calcium phosphate (Ca-P) coatings on porous implants by immersion in simulated physiologic solution. In addition, various Ca-P phases, such as octacalcium phosphate (OCP) or bone-like carbonated apatite (BCA), which are stable only at low

  3. Restoration: Implant with Devastated Platform through Metal Post

    Directory of Open Access Journals (Sweden)

    Luna Salinas Tatiana

    2017-01-01

    Full Text Available Case Presentation. Implant prostheses are a successful treatment for replacing missing teeth. However, this treatment modality can have biological and mechanical complications causing serious problems for the dentist, as demonstrated in this clinical case. The patient presented with a fractured screw and a severely damaged implant hex connection that corresponded to the second premolar, upper left, stating that she unsuccessfully tried to remove the prosthetic screw, which was most likely to have been loose. After clinical and radiographic review, it was decided to remove small fragments of the fractured prosthetic screw inside the implant head. Removal by conventional methods was unsuccessful but was eventually achieved through use of a bur. Then it was possible to make a cast post (gold-palladium and develop a fixed prosthesis (silver-palladium, which were attached with luting cement. A cast post (gold-palladium was made and a fixed prosthesis was developed (silver-palladium, which were attached with luting cement, the same ones that can present mechanical complications such as fractures between the third and fourth thread of the implant, loosening of the abutment, and/or the prosthetic screw in individual crowns, most frequently in partially edentulous patients, mainly in the premolar and molar regions of the maxilla. Conclusion. Therefore the present technique used in this case is very simple, noninvasive, and useful to readers.

  4. Bacterial adherence to tantalum versus commonly used orthopedic metallic implant materials.

    Science.gov (United States)

    Schildhauer, Thomas A; Robie, Bruce; Muhr, Gert; Köller, Manfred

    2006-07-01

    Evaluation of bacterial adhesion to pure tantalum and tantalum-coated stainless steel versus commercially pure titanium, titanium alloy (Ti-6Al-4V), and grit-blasted and polished stainless steel. Experimental in vitro cell culture study using Staphylococcus aureus and Staphylococcus epidermidis to evaluate qualitatively and quantitatively bacterial adherence to metallic implants. A bacterial adhesion assay was performed by culturing S. aureus (ATCC 6538) and S. epidermidis (clinical isolate) for one hour with tantalum, tantalum-coated stainless steel, titanium, titanium alloy, grit-blasted and polished stainless steel metallic implant discs. Adhered living and dead bacteria were stained using a 2-color fluorescence assay. Adherence was then quantitatively evaluated by fluorescence microscopy and digital image processing. Qualitative adherence of the bacteria was analyzed with a scanning electron microscope. The quantitative data were related to the implant surface roughness (Pa-value) as measured by confocal laser scanning microscopy. Bacterial adherence of S. aureus varied significantly (p = 0.0035) with the type of metallic implant. Pure tantalum presented with significantly (p titanium alloy, polished stainless steel, and tantalum-coated stainless steel. Furthermore, pure tantalum had a lower, though not significantly, adhesion than commercially pure titanium and grit-blasted stainless steel. Additionally, there was a significantly higher S. aureus adherence to titanium alloy than to commercially pure titanium (p = 0.014). S. epidermidis adherence was not significantly different among the tested materials. There was no statistically significant correlation between bacterial adherence and surface roughness of the tested implants. Pure tantalum presents with a lower or similar S. aureus and S. epidermidis adhesion when compared with commonly used materials in orthopedic implants. Because bacterial adhesion is an important predisposing factor in the development of

  5. Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC

    International Nuclear Information System (INIS)

    Fritz, Jan; Thawait, Gaurav K.; Fritz, Benjamin; Raithel, Esther; Nittka, Mathias; Gilson, Wesley D.; Mont, Michael A.

    2016-01-01

    Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants. Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant. There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were ''adequate'' to ''good'' on CS-SEMAC and ''non-diagnostic'' to ''adequate'' on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively). Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC. (orig.)

  6. Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, Jan; Thawait, Gaurav K. [Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Section of Musculoskeletal Radiology, Baltimore, MD (United States); Fritz, Benjamin [University of Freiburg, Department of Radiology, Freiburg im Breisgau (Germany); Raithel, Esther; Nittka, Mathias [Siemens Healthcare GmbH, Erlangen (Germany); Gilson, Wesley D. [Siemens Healthcare USA, Inc., Baltimore, MD (United States); Mont, Michael A. [Cleveland Clinic Foundation, Department of Orthopedic Surgery, Cleveland, OH (United States)

    2016-10-15

    Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants. Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant. There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were ''adequate'' to ''good'' on CS-SEMAC and ''non-diagnostic'' to ''adequate'' on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively). Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC. (orig.)

  7. Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.

    Science.gov (United States)

    Pownder, S L; Koff, M F; Shah, P H; Fortier, L A; Potter, H G

    2016-05-01

    Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants. To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences. Nonrandomised in vitro experiment. MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively. Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE. MAVRIC and WBW FSE are feasible additions to minimise artefact around implants. © 2015 EVJ Ltd.

  8. SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

    International Nuclear Information System (INIS)

    Lin, C; Jiang, W; Feng, Y; Huang, Z

    2016-01-01

    Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta_D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta_D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

  9. SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C; Jiang, W [East Carolina University, Greenville, NC (United States); Feng, Y [East Carolina University (United States); Huang, Z [East Carolina University, Greenville, North Carolina (United States)

    2016-06-15

    Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta-D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta-D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

  10. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1α is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1α, VEGF and TNF-α to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages and in vivo. HIF-1α in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1α with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell induced significantly elevated HIF-1α, VEGF, TNF-α and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1α was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n = 5 compared to failed Metal-on-Polymer articulating hip arthroplasties (n = 10. This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy, can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.

  11. Biological Strategies for Improved Osseointegration and Osteoinduction of Porous Metal Orthopedic Implants

    Science.gov (United States)

    Riester, Scott M.; Bonin, Carolina A.; Kremers, Hilal Maradit; Dudakovic, Amel; Kakar, Sanjeev; Cohen, Robert C.; Westendorf, Jennifer J.

    2015-01-01

    The biological interface between an orthopedic implant and the surrounding host tissue may have a dramatic effect upon clinical outcome. Desired effects include bony ingrowth (osseointegration), stimulation of osteogenesis (osteoinduction), increased vascularization, and improved mechanical stability. Implant loosening, fibrous encapsulation, corrosion, infection, and inflammation, as well as physical mismatch may have deleterious clinical effects. This is particularly true of implants used in the reconstruction of load-bearing synovial joints such as the knee, hip, and the shoulder. The surfaces of orthopedic implants have evolved from solid-smooth to roughened-coarse and most recently, to porous in an effort to create a three-dimensional architecture for bone apposition and osseointegration. Total joint surgeries are increasingly performed in younger individuals with a longer life expectancy, and therefore, the postimplantation lifespan of devices must increase commensurately. This review discusses advancements in biomaterials science and cell-based therapies that may further improve orthopedic success rates. We focus on material and biological properties of orthopedic implants fabricated from porous metal and highlight some relevant developments in stem-cell research. We posit that the ideal primary and revision orthopedic load-bearing metal implants are highly porous and may be chemically modified to induce stem cell growth and osteogenic differentiation, while minimizing inflammation and infection. We conclude that integration of new biological, chemical, and mechanical methods is likely to yield more effective strategies to control and modify the implant–bone interface and thereby improve long-term clinical outcomes. PMID:25348836

  12. Metallic ion content and damage to the DNA in oral mucosa cells patients treated dental implants.

    Science.gov (United States)

    López-Jornet, Pía; Perrez, Francisco Parra; Calvo-Guirado, José Luis; Ros-Llor, Irene; LLor-Ros, Irene; Ramírez-Fernández, Piedad

    2014-07-01

    The aim of this study was to assess the potential genotoxicity of dental implants, evaluating biomarkers of DNA damage (micronuclei and/or nuclear buds), cytokinetic defects (binucleated cells) and the presence of trace metals in gingival cells of patients with implants, comparing these with a control group. A total of 60 healthy adults (30 patients with dental implants and 30 control patients without) were included in the study. Medical and dental histories were made for each including life-style factors. Genotoxicity effects were assessed by micronucleus assays in the gingival epithelial cells of each patient; 1,000 epithelial cells were analyzed, evaluating the frequency of micronucleated cells and other nuclear anomalies. The concentration of metals (Al(27), Ag(107), Co (59), Cr (52), Cu(63), Fe(56), Sn(118), Mn(55), Mo(92), Ni(60), Pb(208), Ti(47)) were assayed by means of coupled plasma-mass spectrophotometry (ICP-MS). The frequency of micronuclei in the patient group with implants was higher than in the control group but without statistically significant differences (P > 0.05). Similar results were found for binucleated cells and nuclear buds (P > 0.05). For metals assayed by ICP-MS, significant differences were found for Ti(47) (P ≤ 0.045). Univariate analysis identified a significant association between the presence of micronuclei and age. Dental implants do not induce DNA damage in gingival cells, the slight effects observed cannot be indicated as biologically relevant.

  13. Magnetic resonance imaging metallic artifact of commonly encountered surgical implants and foreign material.

    Science.gov (United States)

    Sutherland-Smith, James; Tilley, Brenda

    2012-01-01

    Magnetic resonance imaging (MRI) artifacts secondary to metallic implants and foreign bodies are well described. Herein, we provide quantitative data from veterinary implants including total hip arthroplasty implants, cranial cruciate repair implants, surgical screws, a skin staple, ligation clips, an identification microchip, ameroid constrictor, and potential foreign bodies including air gun and BB projectiles and a sewing needle. The objects were scanned in a gelatin phantom with plastic grid using standardized T2-weighted turbo-spin echo (TSE), T1-weighted spin echo, and T2*-weighted gradient recalled echo (GRE) image acquisitions at 1.5 T. Maximum linear dimensions and areas of signal voiding and grid distortion were calculated using a DICOM workstation for each sequence and object. Artifact severity was similar between the T2-weighted TSE and T1-weighted images, while the T2*-weighted images were most susceptible to artifact. Metal type influenced artifact size with the largest artifacts arising from steel objects followed by surgical stainless steel, titanium, and lead. For animals with metallic surgical implants or foreign bodies, the quantification of the artifact size will help guide clinicians on the viability of MRI. © 2012 Veterinary Radiology & Ultrasound.

  14. Combined transmission electron microscope and ion channeling study of metastable metal alloys formed by ion implantation

    International Nuclear Information System (INIS)

    Cullis, A.G.; Borders, J.A.; Hirvonen, J.K.; Poate, J.M.

    1977-01-01

    Recently, ion implantation has been used to produce metastable alloy layers with a range of structures from crystalline substitutional solid solutions to amorphous. The technique offers the possibility of producing metastable metal layers with unique physical properties. Its application in the formation of alloys exhibiting different although complementary types of metastability is described. The metal combinations chosen (Ag-Cu and Ta-Cu) show little mutual solubility under equilibrium conditions

  15. AlN metal-semiconductor field-effect transistors using Si-ion implantation

    Science.gov (United States)

    Okumura, Hironori; Suihkonen, Sami; Lemettinen, Jori; Uedono, Akira; Zhang, Yuhao; Piedra, Daniel; Palacios, Tomás

    2018-04-01

    We report on the electrical characterization of Si-ion implanted AlN layers and the first demonstration of metal-semiconductor field-effect transistors (MESFETs) with an ion-implanted AlN channel. The ion-implanted AlN layers with Si dose of 5 × 1014 cm-2 exhibit n-type characteristics after thermal annealing at 1230 °C. The ion-implanted AlN MESFETs provide good drain current saturation and stable pinch-off operation even at 250 °C. The off-state breakdown voltage is 2370 V for drain-to-gate spacing of 25 µm. These results show the great potential of AlN-channel transistors for high-temperature and high-power applications.

  16. Maxillary Overdentures Supported by Four Splinted Direct Metal Laser Sintering Implants: A 3-Year Prospective Clinical Study

    Directory of Open Access Journals (Sweden)

    Francesco Mangano

    2014-01-01

    Full Text Available Purpose. Nowadays, the advancements in direct metal laser sintering (DMLS technology allow the fabrication of titanium dental implants. The aim of this study was to evaluate implant survival, complications, and peri-implant marginal bone loss of DMLS implants used to support bar-retained maxillary overdentures. Materials and Methods. Over a 2-year period, 120 implants were placed in the maxilla of 30 patients (18 males, 12 females to support bar-retained maxillary overdentures (ODs. Each OD was supported by 4 implants splinted by a rigid cobalt-chrome bar. At each annual follow-up session, clinical and radiographic parameters were assessed. The outcome measures were implant failure, biological and prosthetic complications, and peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact, DIB. Results. The 3-year implant survival rate was 97.4% (implant-based and 92.9% (patient-based. Three implants failed. The incidence of biological complication was 3.5% (implant-based and 7.1% (patient-based. The incidence of prosthetic complication was 17.8% (patient-based. No detrimental effects on marginal bone level were evidenced. Conclusions. The use of 4 DMLS titanium implants to support bar-retained maxillary ODs seems to represent a safe and successful procedure. Long-term clinical studies on a larger sample of patients are needed to confirm these results.

  17. Maxillary overdentures supported by four splinted direct metal laser sintering implants: a 3-year prospective clinical study.

    Science.gov (United States)

    Mangano, Francesco; Luongo, Fabrizia; Shibli, Jamil Awad; Anil, Sukumaran; Mangano, Carlo

    2014-01-01

    Purpose. Nowadays, the advancements in direct metal laser sintering (DMLS) technology allow the fabrication of titanium dental implants. The aim of this study was to evaluate implant survival, complications, and peri-implant marginal bone loss of DMLS implants used to support bar-retained maxillary overdentures. Materials and Methods. Over a 2-year period, 120 implants were placed in the maxilla of 30 patients (18 males, 12 females) to support bar-retained maxillary overdentures (ODs). Each OD was supported by 4 implants splinted by a rigid cobalt-chrome bar. At each annual follow-up session, clinical and radiographic parameters were assessed. The outcome measures were implant failure, biological and prosthetic complications, and peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact, DIB). Results. The 3-year implant survival rate was 97.4% (implant-based) and 92.9% (patient-based). Three implants failed. The incidence of biological complication was 3.5% (implant-based) and 7.1% (patient-based). The incidence of prosthetic complication was 17.8% (patient-based). No detrimental effects on marginal bone level were evidenced. Conclusions. The use of 4 DMLS titanium implants to support bar-retained maxillary ODs seems to represent a safe and successful procedure. Long-term clinical studies on a larger sample of patients are needed to confirm these results.

  18. Transport in silicon-germanium heterostructures

    International Nuclear Information System (INIS)

    Chrastina, Daniel

    2001-01-01

    The work presented here describes the electrical characterization of n- and p-type strained silicon-germanium systems. Theories of quantum transport m low magnetic fields at low temperature are discussed m terms of weak-localization: the traditional theory is shown not to account for the dephasing in a 2-dimensional hole gas behaving in a metallic manner and emergent alternative theories, while promising, require refinement. The mobility as a function of sheet density is measured in a p-type pseudomorphic Si 0.5 Ge 0.5 across the temperature range 350mK-282K; it is shown that calculations of the mobility based on semi-classical scattering mechanisms fail below 10K where quantum transport effects become relevant. A room temperature Hall scattering factor has been extracted. A new functional form has been presented to fit the resistivity as a function of temperature, below 20K: traditional theories of screening and weak localization appear not to be applicable. It is also demonstrated that simple protection circuitry is essential if commercial-scale devices are to be meaningfully investigated. Mobility spectrum analysis is performed on an n-type strained-silicon device. Established analysis methods are discussed and a new method is presented based on the Bryan's Algorithm approach to maximum entropy. The breakdown of the QHE is also investigated: the critical current density compares well to that predicted by an existing theory. Finally, devices in which both electron and hole gases can be induced are investigated. However, it is shown that the two cannier species never co-exist. Design rules are presented which may allow more successful structures to be created. Results are presented which demonstrate the success and the utility of implanted contacts which selectively reach different regions of the structure. (author)

  19. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

    Science.gov (United States)

    Wang, Xiaojian; Xu, Shanqing; Zhou, Shiwei; Xu, Wei; Leary, Martin; Choong, Peter; Qian, M; Brandt, Milan; Xie, Yi Min

    2016-03-01

    One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Comparison of Self-Expanding Polyethylene Terephthalate and Metallic Stents Implanted in Porcine Iliac Arteries

    International Nuclear Information System (INIS)

    Wilczek, Krzysztof; Scheerder, Ivan de; Wang Kai; Verbeken, Eric; Piessens, Jan

    1996-01-01

    Purpose: Comparison of the biocompatibility of self-expanding polyethylene terephthalate (PET) stents with self-expanding metallic stents (Wallstents). Methods: Diameter- and length-matched PET stents and Wallstents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographically and with intravascular ultrasound immediately after stent implantation. The angiographic stented lumen diameter was measured using quantitative vessel analysis before, immediately after stenting, and at 6-week follow-up. Cross-section histopathology and area morphometry were performed. Results: Immediately poststenting, intravascular ultrasound revealed proximal dislocation of 5 of the 13 PET stents, whereas all metal stents were firmly embedded at the implantation site. At 6-week follow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diameter within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p < 0.02). This observation was confirmed by postmortem morphometry, wherein the PET-stented vessel segments a diameter stenosis of 40% was measured vs only 9% in the metallic stents (p < 0.0001). Conclusion: PET-stent deployment is difficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neointimal proliferation than metallic stents

  1. Study by nuclear techniques of the impurity-defect interaction in implanted metals

    International Nuclear Information System (INIS)

    Thome, Lionel.

    1978-01-01

    The properties of out equilibrium alloys formed by impurity implantation are strongly influenced by radiation damage created during implantation. This work presents a study, via hyperfine interaction and lattice location experiments, of the impurity-defect interaction in ion implanted metals. When the impurity and defect concentrations in the implanted layer are small, i.e. when impurities are uniformly recoil implanted in the whole crystal volume following a nuclear reaction (Aq In experiments), the impurity interacts with its own damage cascade. In this case, a vacancy is found to be trapped by a fraction of impurities during an athermal process. The value of this fraction does not seem to depend critically on impurity and host. When the impurity and defect concentrations are such that defect cascades interact, i.e. when impurities are implanted with an isotope separator (Fe Yb experiments), the observed impurity-vacancy (or vacancy cluster) interactions depend then strongly on the nature of impurity and host. An empirical relation, which indicates the importance of elastic effects, has been found between the proportion of impurities interacting with defects and the difference between impurity and host atom radii. At implantation temperature such that vacancies are mobile, the impurity-defect interaction depends essentially on vacancy migration. A model based on chemical kinetics has been developed to account for the variation with temperature of measured quantities [fr

  2. Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

    Science.gov (United States)

    Mangano, F.; Chambrone, L.; van Noort, R.; Miller, C.; Hatton, P.; Mangano, C.

    2014-01-01

    Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed. PMID:25525434

  3. Direct metal laser sintering titanium dental implants: a review of the current literature.

    Science.gov (United States)

    Mangano, F; Chambrone, L; van Noort, R; Miller, C; Hatton, P; Mangano, C

    2014-01-01

    Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

  4. Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

    Directory of Open Access Journals (Sweden)

    F. Mangano

    2014-01-01

    Full Text Available Statement of Problem. Direct metal laser sintering (DMLS is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs; to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

  5. Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted 163Ho ions

    Science.gov (United States)

    Gastaldo, L.; Ranitzsch, P. C.-O.; von Seggern, F.; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

    2013-05-01

    For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of 163Ho using MMCs having the radioactive 163Ho ions implanted in the absorber. The isotope 163Ho decays through electron capture to 163Dy and features the smallest known QEC value. This peculiarity makes 163Ho a very interesting candidate to investigate the value of the electron neutrino mass by the analysis of the energy spectrum. The implantation of 163Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. Moreover the performance of the detector prototype having the 163Ho ions implanted in the absorber is already close to the requirements needed for an experiment with sub-eV sensitivity to the electron neutrino mass. Based on these results, an optimized detector design for future 163Ho experiments is presented.

  6. Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted 163Ho ions

    International Nuclear Information System (INIS)

    Gastaldo, L.; Ranitzsch, P.C.-O.; Seggern, F. von; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

    2013-01-01

    For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of 163 Ho using MMCs having the radioactive 163 Ho ions implanted in the absorber. The isotope 163 Ho decays through electron capture to 163 Dy and features the smallest known Q EC value. This peculiarity makes 163 Ho a very interesting candidate to investigate the value of the electron neutrino mass by the analysis of the energy spectrum. The implantation of 163 Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. Moreover the performance of the detector prototype having the 163 Ho ions implanted in the absorber is already close to the requirements needed for an experiment with sub-eV sensitivity to the electron neutrino mass. Based on these results, an optimized detector design for future 163 Ho experiments is presented

  7. Unrecoverable bi-products of drilling titanium alloy and tantalum metal implants: a pilot study.

    Science.gov (United States)

    Skowronek, Paweł; Olszewski, Paweł; Święszkowski, Wojciech; Synder, Marek; Sibiński, Marcin; Mazek, Jacek

    2018-05-01

    Trabecular metal implants with a porous architecture that allows for the incorporation of bone into the implant during healing are gaining popularity in alloplastic revision procedures. The bi-products of drilling titanium alloy (Ti) and tantalum (Ta) implants have not been previously assessed. Four holes were drilled in each of two spatially porous trabecular implants, one Ta and the other Ti alloy (Ti-6Al-7Nb), for this pilot in vitro study. The particles were flushed out with a continuous flow of saline. The particles' weight and the volume were then measured using a Radwag XA 110/2X (USA) laboratory balance. The total volume of the obtained metal fines was measured by titration using a 10 mm 3 measurement system. A cobalt carbide bit was used since the holes could not be made with a standard bone drill. Each Ti and Ta implant lost 1.26 g and 2.48 g of mass, respectively. The volume of free particles recovered after each stage was 280 mm 3 and 149 mm 3 , respectively. Approximately 0.6% of the total implant mass was not recovered after drilling (roughly 2% of the mass of the particles created by drilling), despite the use of 5 µm filters. It is technically difficult to drill holes in Ti and Ta implants using standard surgical tools. The drilling process creates a considerable amount of metal particles, which cannot be recovered despite intensive flushing. This may have an adverse influence on the bio-functionality (survival) of the endoprosthesis and present deleterious systemic consequences.

  8. Surface-conductivity enhancement of PMMA by keV-energy metal-ion implantation

    International Nuclear Information System (INIS)

    Bannister, M.E.; Hijazi, H.; Meyer, H.M.; Cianciolo, V.; Meyer, F.W.

    2014-01-01

    An experiment has been proposed to measure the neutron electric dipole moment (nEDM) with high precision at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source. One of the requirements of this experiment is the development of PMMA (Lucite) material with a sufficiently conductive surface to permit its use as a high-voltage electrode while immersed in liquid He. At the ORNL Multicharged Ion Research Facility, an R and D activity is under way to achieve suitable surface conductivity in poly-methyl methacrylate (PMMA) using metal ion implantation. The metal implantation is performed using an electron-cyclotron-resonance (ECR) ion source and a recently developed beam line deceleration module that is capable of providing high flux beams for implantation at energies as low as a few tens of eV. The latter is essential for reaching implantation fluences exceeding 1 × 10 16 cm −2 , where typical percolation thresholds in polymers have been reported. In this contribution, we report results on initial implantation of Lucite by Ti and W beams with keV energies to average fluences in the range 0.5–6.2 × 10 16 cm −2 . Initial measurements of surface-resistivity changes are reported as function of implantation fluence, energy, and sample temperature. We also report X-ray photoelectron spectroscopy (XPS) surface and depth profiling measurements of the ion implanted samples, to identify possible correlations between the near surface and depth resolved implanted W concentrations and the measured surface resistivities

  9. Metal Ion Concentrations in Body Fluids after Implantation of Hip Replacements with Metal-on-Metal Bearing – Systematic Review of Clinical and Epidemiological Studies

    Science.gov (United States)

    Hartmann, Albrecht; Hannemann, Franziska; Lützner, Jörg; Seidler, Andreas; Drexler, Hans; Günther, Klaus-Peter; Schmitt, Jochen

    2013-01-01

    Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip

  10. Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

    Directory of Open Access Journals (Sweden)

    Albrecht Hartmann

    Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

  11. A comparative study of the accuracy between plastic and metal impression transfer copings for implant restorations.

    Science.gov (United States)

    Fernandez, Monica A; Paez de Mendoza, Carmen Y; Platt, Jeffrey A; Levon, John A; Hovijitra, Suteera T; Nimmo, Arthur

    2013-07-01

    A precise transfer of the position and orientation of the antirotational mechanism of an implant to the working cast is particularly important to achieve optimal fit of the final restoration. This study evaluated and compared the accuracy of metal and plastic impression copings for use in a full-arch mandibular edentulous simulation with four implants. Metal and plastic impression transfer copings for two implant systems, Nobel Biocare™ Replace and Straumann SynOcta®, were assessed on a laboratory model to simulate clinical practice. The accuracy of producing stone casts using these plastic and metal impression transfer copings was measured against a standard prosthetic framework consisting of a cast gold bar. A total of 20 casts from the four combinations were obtained. The fit of the framework on the cast was tested by a noncontact surface profilometer, the Proscan 3D 2000 A, using the one-screw test. The effects of implant/system and impression/coping material on gap measurements were analyzed using repeated measures ANOVA. The findings of this in vitro study were as follows: plastic copings demonstrated significantly larger average gaps than metal for Straumann (p = 0.001). Plastic and metal copings were not significantly different for Nobel (p = 0.302). Nobel had significantly larger average gaps than Straumann for metal copings (p = 0.003). Nobel had marginally smaller average gaps than Straumann (p = 0.096) for plastic copings. The system-by-screw location interaction was significant as well (p impression copings were more accurate than plastic copings when using the Straumann system, and there was no difference between metal and plastic copings for the Nobel Replace system. The system-by-screw location was not conclusive, showing no correlation within each system. © 2013 by the American College of Prosthodontists.

  12. Calibration of germanium detectors

    International Nuclear Information System (INIS)

    Debertin, K.

    1983-01-01

    The process of determining the energy-dependent detection probability with measurements using Ge (Li) and high-grade germanium detectors is described. The paper explains which standards are best for a given purpose and given requirements as to accuracy, and how to assess measuring geometry variations and summation corrections. (DG) [de

  13. Electrochemical removal of metallic implants from Technovit 9100 New embedded hard and soft tissues prior to histological sectioning.

    Science.gov (United States)

    Willbold, Elmar; Reebmann, Mattias; Jeffries, Richard; Witte, Frank

    2013-11-01

    Solid metallic implants in soft or hard tissues are serious challenges for histological processing. However, metallic implants are more frequently used in e.g. cardiovascular or orthopaedic therapies. Before clinical use, these devices need to be tested thoroughly in a biological environment and histological analysis of their biocompatibility is a major requirement. To allow the histological analysis of metallic implants in tissues especially in calcified hard tissues, we describe a method for embedding these tissues in the resin Technovit 9100 New and removing the metallic implants by electrochemical dissolution. With the combination of these two processes, we are able to achieve 5 μm thick sections from soft or hard tissues with a superior preservation of tissue architecture and especially the implant-tissue interface. These sections can be stained by classical stainings, immunohistochemical and enzymehistochemical as well as DNA-based staining methods.

  14. Hip Implant Systems

    Science.gov (United States)

    ... Implants and Prosthetics Metal-on-Metal Hip Implants Hip Implants Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Hip implants are medical devices intended to restore mobility ...

  15. The Metal-Zirconia Implant Fixed Hybrid Full-Arch Prosthesis: An Alternative Technique for Fabrication.

    Science.gov (United States)

    Stumpel, Lambert J; Haechler, Walter

    2018-03-01

    The metal-resin hybrid full-arch prosthesis has been a traditionally used type of restoration for full-arch implant fixed dentures. A newer development has centered around the use of monolithic zirconia or zirconia veneered with porcelain. Being a ceramic, zirconia has the potential for fracture. This article describes a technique that utilizes a metal substructure to support a chemically and mechanically resinbonded shell of zirconia. The workflow is discussed, ranging from in-office master cast fabrication to the CAD/ CAM production of the provisional and the definitive metal-zirconia prosthesis. The article also highlights the advantages and disadvantages of various materials used for hybrid prostheses.

  16. Transition metal implanted ZnO. A correlation between structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengqiang

    2008-07-01

    Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors question the origin of this ferromagnetism, i.e. if the observed ferromagnetism stems from ferromagnetic precipitates rather than from carriermediated magnetic coupling of ionic impurities, as required for a diluted magnetic semiconductor. In this thesis, this question will be answered for transition-metal implanted ZnO single crystals. Magnetic secondary phases, namely metallic Fe, Co and Ni nanocrystals, are formed inside ZnO. They are - although difficult to detect by common approaches of structural analysis - responsible for the observed ferromagnetism. Particularly Co and Ni nanocrystals are crystallographically oriented with respect to the ZnO matrix. Their structure phase transformation and corresponding evolution of magnetic properties upon annealing have been established. Finally, an approach, pre-annealing ZnO crystals at high temperature before implantation, has been demonstrated to sufficiently suppress the formation of metallic secondary phases. (orig.)

  17. PATIENTS WITH SUSPECTED METAL IMPLANT ALLERGY: POTENTIAL CLINICAL PICTURES AND ALLERGOLOGICAL DIAGNOSTIC APPROACH (REVIEW

    Directory of Open Access Journals (Sweden)

    P. Thomas

    2014-01-01

    Full Text Available The focus of this review are allergic complications following insertion of metallic orthopedic implants. Such potential allergic reactions encompass eczema, impaired wound and fracture healing, infection-mimicking reactions, effusions, pain and loosening. Nickel, cobalt and chromium seem to be the predominant eliciting allergens. Allergy might be considered prior to planned orthopaedic surgery or in patients with complications following arthroplasty We recommend, that differential diagnoses - in particular infection -should always be excluded in cooperation with surgery collegues. The clinical work up of a patient suspected of suffering from metal implant allergy should include a combined evaluation of medical history, clinical findings, patch testing and histology In vitro testing, namely the lymphocyte transformation test (LTT, can indicate metal sensitization, but needs careful interpretation.

  18. Peripheral white blood cells profile of biodegradable metal implant in mice animal model

    Science.gov (United States)

    Paramitha, Devi; Noviana, Deni; Estuningsih, Sri; Ulum, Mokhamad Fakhrul; Nasution, Ahmad Kafrawi; Hermawan, Hendra

    2015-09-01

    Biocompatibility or safety of the medical device is considered important. It can be determined by blood profile examination. The aim of this study was to assess the biocompatibility of biodegradable metal implant through peripheral white blood cells (WBCs) profile approach. Forty eight male ddy mice were divided into four groups according to the materials implanted: iron wire (Fe), magnesium rod (Mg), stainless steel surgical wire (SS316L) and control with sham (K). Implants were inserted and attached onto the right femoral bone on latero-medial region. In this study, peripheral white blood cells and leukocyte differentiation were the parameters examined. The result showed that the WBCs value of all groups were decreased at the first day after implantation, increased at the 10th day and continued increasing at the 30th day of observation, except Mg group which has decreased. Neutrophil, as an inflammatory cells, was increased at the early weeks and decreased at the day-30 after surgery in all groups. Despite, these values during the observation were still within the normal range. As a conclus ion, biodegradable metal implants lead to an inflammatory reaction, with no adverse effect on WBC value found.

  19. Surface modification of ceramics and metals by ion implantation combined with plasma irradiation

    International Nuclear Information System (INIS)

    Miyagawa, Soji; Miyagawa, Yoshiko; Nakao, Setsuo; Ikeyama, Masami; Saitoh, Kazuo

    2000-01-01

    To develop a new surface modification technique using ion implantation combined with plasma irradiation, thin film formation by IBAD (Ion Beam Assisted Deposition) and atom relocation processes such as radiation enhanced diffusion and ion beam mixing under high dose implantation have been studied. It was confirmed that the computer simulation code, dynamic-SASAMAL (IBAD version) developed in this research, is quite useful to evaluate ballistic components in film formation by high dose implantation on ceramics and metals, by ion beam mixing of metal-ceramics bi-layer and by the IBAD method including hydrocarbon deposition. Surface modification process of SiC by simultaneous irradiation of ions with a radical beam has also been studied. A composite of SiC and β-Si 3 N 4 was found to be formed on a SiC surface by hot implantation of nitrogen. The amount of β- Si 3 N 4 crystallites increased with increasing the dosage of the hydrogen radical beam during nitrogen implantation. (author)

  20. Crohn’s disease and Trabecular Metal implants: a report of two cases and literature review

    Directory of Open Access Journals (Sweden)

    C. Peron

    2015-10-01

    Full Text Available Aim The aim of the present study was to report two cases with Crohn’s disease in whom dental implants successfully osseointegrated and remained functionally stable up to 13 and 12 months of follow-up, respectively. Cases presentation In cases 1 (age 35 years and 2 (age 36 years, tooth 24 and 14, respectively, were atraumatically extracted and a particulated bone grafting material (buccal and palatal aspect of the defect and a Trabecular Metal implant (11.5 mm length, 4.7 mm diameter were inserted in each extraction socket. After implant placement and abutment connection with the final torque (25 Ncm, the provisional restoration was adapted in the oral cavity creating the emergence profile. The provisional crown was screw-retained and had slight occlusal contacts in the centric occlusion (intercuspation position. A periapical radiograph was taken as a control radiograph at the baseline. Postoperatively, antibiotics were prescribed as well as analgesics and an oral rinse was recommended. In both cases, the provisional restoration was removed after 2 weeks and replaced with a full ceramic restoration. Case-1 and case-2 were followed up after 13 months and 12 months respectively. In both cases postoperative healing was uneventful and radiographs taken at follow-up showed no evidence of crestal bone loss. Implants in both cases demonstrated an excellent clinical condition at follow-up. Conclusion Trabecular Metal implants can osseointegrate and remain functionally stable in patients with Crohn’s disease.

  1. Peripheral white blood cells profile of biodegradable metal implant in mice animal model

    Energy Technology Data Exchange (ETDEWEB)

    Paramitha, Devi; Noviana, Deni, E-mail: deni@ipb.ac.id; Estuningsih, Sri [Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor (Indonesia); Ulum, Mokhamad Fakhrul [Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor (Indonesia); Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia (UTM), Johor Bahru (Malaysia); Nasution, Ahmad Kafrawi [Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia (UTM), Johor Bahru (Malaysia); Faculty of Engineering, Muhammadiyah University of Riau (UMRI), Pekanbaru (Indonesia); Hermawan, Hendra [Department of Mining, Metallurgical and Materials Engineering & CHU de Québec Research Center, Laval University (ULaval) (Canada)

    2015-09-30

    Biocompatibility or safety of the medical device is considered important. It can be determined by blood profile examination. The aim of this study was to assess the biocompatibility of biodegradable metal implant through peripheral white blood cells (WBCs) profile approach. Forty eight male ddy mice were divided into four groups according to the materials implanted: iron wire (Fe), magnesium rod (Mg), stainless steel surgical wire (SS316L) and control with sham (K). Implants were inserted and attached onto the right femoral bone on latero-medial region. In this study, peripheral white blood cells and leukocyte differentiation were the parameters examined. The result showed that the WBCs value of all groups were decreased at the first day after implantation, increased at the 10th day and continued increasing at the 30th day of observation, except Mg group which has decreased. Neutrophil, as an inflammatory cells, was increased at the early weeks and decreased at the day-30 after surgery in all groups. Despite, these values during the observation were still within the normal range. As a conclus ion, biodegradable metal implants lead to an inflammatory reaction, with no adverse effect on WBC value found.

  2. In vitro corrosion behavior of bioceramic, metallic, and bioceramic-metallic coated stainless steel dental implants.

    Science.gov (United States)

    Fathi, M H; Salehi, M; Saatchi, A; Mortazavi, V; Moosavi, S B

    2003-05-01

    The most common metals and alloys used in dentistry may be exposed to a process of corrosion in vivo that make them cytotoxic. The biocompatibility of dental alloys is primarily related to their corrosion behavior. The aim of this work was to evaluate the corrosion behavior and thus the biocompatibility of the uncoated and coated stainless steels and compare the effect of type of coatings on corrosion behavior. Three types of coatings, hydroxyapatite (HA), titanium (Ti), and a double-layer HA/Ti on AISI 316L stainless steel were made. HA coating was produced using plasma-spraying technique and Ti coating was made using physical vapor deposition process. In order to perform a novel double-layer composite coating, a top layer of HA was plasma-sprayed over a physical vapor deposited Ti layer on AISI 316L stainless steel. Structural characterization techniques including XRD, SEM and EDX were used to investigate the microstructure, morphology and crystallinity of the coatings. Electrochemical potentiodynamic tests were performed in physiological solutions in order to determine and compare the corrosion behavior of the coated and uncoated specimens as an indication of biocompatibility. Double-layer HA/Ti coating on AISI 316L SS had a positive effect on improvement of corrosion behavior. The decrease in corrosion current densities was significant for these coated specimens and was much lower than the values obtained for uncoated and single HA coated specimens. Ti coating on AISI 316L SS also has a beneficial effect on corrosion behavior. The results were compared with the results of corrosion behavior of HA coated commercially pure titanium (cpTi) and uncoated cpTi. These results demonstrated that the double-layer HA/Ti coated 316L SS can be used as an endodontic implant and two goals including improvement of corrosion resistance and bone osteointegration can be obtained simultaneously.

  3. Very broad beam metal ion source for large area ion implantation application

    International Nuclear Information System (INIS)

    Brown, I.; Anders, S.; Dickinson, M.R.; MacGill, R.A.; Yao, X.

    1993-01-01

    The authors have made and operated a very broad beam version of vacuum arc ion source and used it to carry out high energy metal ion implantation of a particularly large substrate. A multiple-cathode vacuum arc plasma source was coupled to a 50 cm diameter beam extractor (multiple aperture, accel-decel configuration) operated at a net extraction voltage of up to 50 kV. The metal ion species chosen were Ni and Ta. The mean ion charge state for Ni and Ta vacuum arc plasmas is 1.8 and 2.9, respectively, and so the mean ion energies were up to about 90 and 145 keV, respectively. The ion source was operated in a repetitively pulsed mode with pulse length 250 μs and repetition rate several pulses per second. The extracted beam had a gaussian profile with FWHM about 35 cm, giving a nominal beam area of about 1,000 cm 2 . The current of Ni or Ta metal ions in the beam was up to several amperes. The targets for the ion implantation were a number of 24-inch long, highly polished Cu rails from an electromagnetic rail gun. The rails were located about 80 cm away from the ion source extractor grids, and were moved across a diameter of the vessel in such a way as to maximize the uniformity of the implant along the rail. The saturation retained dose for Ta was limited to about 4 x 10 16 cm -2 because of the rather severe sputtering, in accordance with the theoretical expectations for these implantation conditions. Here they describe the ion source, the implantation procedure, and the kinds of implants that can be produced in this way

  4. Spectral Analysis Related to Bare-Metal and Drug-Eluting Coronary Stent Implantation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Rose Mary Ferreira Lisboa da, E-mail: roselisboa@cardiol.br [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Silva, Carlos Augusto Bueno [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Greco, Otaviano José [Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Moreira, Maria da Consolação Vieira [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil)

    2014-08-15

    The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia. To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent. This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure. Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment. Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.

  5. Optimized protocols for cardiac magnetic resonance imaging in patients with thoracic metallic implants.

    Science.gov (United States)

    Olivieri, Laura J; Cross, Russell R; O'Brien, Kendall E; Ratnayaka, Kanishka; Hansen, Michael S

    2015-09-01

    Cardiac magnetic resonance (MR) imaging is a valuable tool in congenital heart disease; however patients frequently have metal devices in the chest from the treatment of their disease that complicate imaging. Methods are needed to improve imaging around metal implants near the heart. Basic sequence parameter manipulations have the potential to minimize artifact while limiting effects on image resolution and quality. Our objective was to design cine and static cardiac imaging sequences to minimize metal artifact while maintaining image quality. Using systematic variation of standard imaging parameters on a fluid-filled phantom containing commonly used metal cardiac devices, we developed optimized sequences for steady-state free precession (SSFP), gradient recalled echo (GRE) cine imaging, and turbo spin-echo (TSE) black-blood imaging. We imaged 17 consecutive patients undergoing routine cardiac MR with 25 metal implants of various origins using both standard and optimized imaging protocols for a given slice position. We rated images for quality and metal artifact size by measuring metal artifact in two orthogonal planes within the image. All metal artifacts were reduced with optimized imaging. The average metal artifact reduction for the optimized SSFP cine was 1.5+/-1.8 mm, and for the optimized GRE cine the reduction was 4.6+/-4.5 mm (P metal artifact reduction for the optimized TSE images was 1.6+/-1.7 mm (P metal artifact are easily created by modifying basic sequence parameters, and images are superior to standard imaging sequences in both quality and artifact size. Specifically, for optimized cine imaging a GRE sequence should be used with settings that favor short echo time, i.e. flow compensation off, weak asymmetrical echo and a relatively high receiver bandwidth. For static black-blood imaging, a TSE sequence should be used with fat saturation turned off and high receiver bandwidth.

  6. Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome

    Science.gov (United States)

    2016-12-01

    bodies in soft tissue causing plumbism 36-38. There are no strict guidelines as to when patients with gunshot or other metal fragment wounds should...Immunological changes in patients with primary osteoarthritis of the hip after total joint rep lacement. J Bone Joint Surg Br 2003 Jul;85(5):758-64

  7. Battlefield Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome

    Science.gov (United States)

    2014-10-01

    36-38 . There are no strict guidelines as to when patients with gunshot or other metal fragment wounds should be tested to determine serum lead...Immunological changes in patients with primary osteoarthritis of the hip after total joint replacement. J Bone Joint Surg Br 2003 Jul;85(5):758-64. (52

  8. MR imaging near metallic implants using MAVRIC SL: initial clinical experience at 3T.

    Science.gov (United States)

    Gutierrez, Luis B; Do, Bao H; Gold, Garry E; Hargreaves, Brian A; Koch, Kevin M; Worters, Pauline W; Stevens, Kathryn J

    2015-03-01

    To compare the effectiveness of multiacquisition with variable resonance image combination selective (MAVRIC SL) with conventional two-dimensional fast spin-echo (2D-FSE) magnetic resonance (MR) techniques at 3T in imaging patients with a variety of metallic implants. Twenty-one 3T MR studies were obtained in 19 patients with different types of metal implants. Paired MAVRIC SL and 2D-FSE sequences were reviewed by two radiologists and compared for in-plane and through-plane metal artifact, visualization of the bone implant interface and surrounding soft tissues, blurring, and overall image quality using a two-tailed Wilcoxon signed rank test. The area of artifact on paired images was measured and compared using a paired Wilcoxon signed rank test. Changes in patient management resulting from MAVRIC SL imaging were documented. Significantly less in-plane and through-plane artifact was seen with MAVRIC SL, with improved visualization of the bone-implant interface and surrounding soft tissues, and superior overall image quality (P = .0001). Increased blurring was seen with MAVRIC SL (P = .0016). MAVRIC SL significantly decreased the image artifact compared to 2D-FSE (P = .0001). Inclusion of MAVRIC SL to the imaging protocol determined the need for surgery or type of surgery in five patients and ruled out the need for surgery in 13 patients. In three patients, the area of interest was well seen on both MAVRIC SL and 2D-FSE images, so the addition of MAVRIC had no effect on patient management. Imaging around metal implants with MAVRIC SL at 3T significantly improved image quality and decreased image artifact compared to conventional 2D-FSE imaging techniques and directly impacted patient management. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  9. Non-metallic implant for patellar fracture fixation: A systematic review.

    Science.gov (United States)

    Camarda, Lawrence; Morello, Salvatore; Balistreri, Francesco; D'Arienzo, Antonio; D'Arienzo, Michele

    2016-08-01

    Despite good clinical outcome proposals, there has been relatively little published regarding the use of non-metallic implant for patellar fracture fixation. The purpose of the study was to perform a systematic literature review to summarize and evaluate the clinical studies that described techniques for treating patella fractures using non-metallic implants. A comprehensive literature search was systematically performed to evaluate all studies included in the literature until November 2015. The following search terms were used: patellar fracture, patella suture, patella absorbable, patella screw, patella cerclage. Two investigators independently reviewed all abstracts and the selection of these abstracts was then performed based on inclusion and/or exclusion criteria. A total of 9 studies involving 123 patients were included. Patients had a mean age of 33.7 years and were followed up for a mean of 18.9 months. The most common method for fracture fixations included the use of suture material. Good clinical outcomes were reported among all studies. Thirteen patients (10.5%) presented complications, while 4 patients (3.2%) required additional surgery for implant removal. There is a paucity of literature focused on the use of non-metallic implant for patellar fracture fixation. However, this systematic review showed that non-metallic implants are able to deliver good clinical outcomes reducing the rate of surgical complications and re-operation. These results may assist surgeons in choosing to use alternative material such as sutures to incorporate into their routine practice or to consider it, in order to reduce the rate of re-operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. MRI Near Metallic Implants Using MAVRIC SL: Initial Clinical Experience at 3T

    Science.gov (United States)

    Gutierrez, Luis B.; Do, Bao H.; Gold, Garry E.; Hargreaves, Brian A.; Koch, Kevin M.; Worters, Pauline W.; Stevens, Kathryn J.

    2014-01-01

    Rationale and Objectives To compare the effectiveness of MAVRIC SL with conventional 2D-FSE MR techniques at 3T in imaging patients with a variety of metallic implants. Materials and Methods Twenty-one 3T MR studies were obtained in 19 patients with different types of metal implants. Paired MAVRIC SL and 2D-FSE sequences were reviewed by 2 radiologists, and compared for in-plane and through-plane metal artifact, visualization of the bone implant interface and surrounding soft tissues, blurring, and overall image quality using a 2-tailed Wilcoxon signed rank test. The area of artifact on paired images was measured and compared using a paired Wilcoxon signed rank test. Changes in patient management resulting from MAVRIC SL imaging were documented. Results Significantly less in-plane and through-plane artifact was seen with MAVRIC SL, with improved visualization of the bone-implant interface and surrounding soft tissues, and superior overall image quality (p = 0.0001). Increased blurring was seen with MAVRIC SL (p=0.0016). MAVRIC SL significantly decreased the image artifact compared to 2D-FSE (p=0.0001). Inclusion of MAVRIC SL to the imaging protocol determined the need for surgery or type of surgery in 5 patients, and ruled out the need for surgery in 13 patients. In 3 patients the area of interest was well seen on both MAVRIC SL and 2D-FSE images, so the addition of MAVRIC had no effect on patient management. Conclusion Imaging around metal implants with MAVRIC SL at 3T significantly improved image quality and decreased image artifact compared to conventional 2D-FSE imaging techniques, and directly impacted patient management. PMID:25435186

  11. Quasi-static strength and fractography analysis of two dental implants manufactured by direct metal laser sintering.

    Science.gov (United States)

    Gehrke, Sergio Alexandre; Pérez-Díaz, Leticia; Dedavid, Berenice Anina

    2018-01-30

    New manufacturing methods was developed to improve the tissues integration with the titanium alloy pieces. The present in vitro study was to assess the resistance and fracture mode after applied a quasi-static compressive force on the two dental implants manufactured by direct metal laser sintering. Twenty dental implants manufactured by direct metal laser sintering, using titanium alloy (Ti-6Al-4V) granules in two designs (n = 10 per group): Conventional dental implant (group Imp1) two-piece implant design, where the surgical implant and prosthetic abutment are two separate components and, the one-piece implant (group Imp2), where the surgical implant and prosthetic abutment are one integral piece. All samples were subjected to quasi-static loading at a 30° angle to the implant axis in a universal testing machine. The mean fracture strengths were 1269.2 ± 128.8 N for the group Imp1 and, 1259.5 ± 115.1 N for the group Imp2, without statistical differences (P = .8722). In both groups, the fracture surface does not present crack between the compact core and the superficial (less dense and porous) part of the implants. Based on the measured resistance data for the two implant models manufactured by direct metal laser sintering tested in the present study, we can suggest that they have adequate capacity to withstand the masticatory loads. © 2018 Wiley Periodicals, Inc.

  12. Surface modification of the hard metal tungsten carbide-cobalt by boron ion implantation

    International Nuclear Information System (INIS)

    Mrotchek, I.

    2007-01-01

    In the present thesis ion beam implantation of boron is studied as method for the increasement of the hardness and for the improvement of the operational characteristics of cutting tools on the tungsten carbide-cobalt base. For the boron implantation with 40 keV energy and ∼5.10 17 ions/cm 2 fluence following topics were shown: The incoerporation of boron leads to a deformation and remaining strain of the WC lattice, which possesses different stregth in the different directions of the elementary cell. The maximum of the deformation is reached at an implantation temperature of 450 C. The segregation of the new phases CoWB and Co 3 W was detected at 900 C implantation temperature. At lower temperatures now new phases were found. The tribological characteristics of WC-Co are improved. Hereby the maxiaml effect was measured for implantation temperatures from 450 C to 700 C: Improvement of the microhardness by the factor 2..2.5, improvement of the wear resistance by the factor 4. The tribological effects extend to larger depths than the penetration depth of the boron implantation profile. The detected property improvements of the hard metal H3 show the possibility of a practical application of boron ion implantation in industry. The effects essential for a wer decreasement are a hardening of the carbide phase by deformation of the lattice, a hardening of the cobalt binding material and the phase boundaries because of the formation of a solid solution of the implanted boron atoms in Co and by this a blocking of the dislocation movement and the rupture spreading under load

  13. Potential release of in vivo trace metals from metallic medical implants in the human body: from ions to nanoparticles--a systematic analytical review.

    Science.gov (United States)

    Matusiewicz, Henryk

    2014-06-01

    Metal ion release from metallic materials, e.g. metallic alloys and pure metals, implanted into the human body in dental and orthopedic surgery is becoming a major cause for concern. This review briefly provides an overview of both metallic alloys and pure metals used in implant materials in dental and orthopedic surgery. Additionally, a short section is dedicated to important biomaterials and their corrosive behavior in both real solutions and various types of media that model human biological fluids and tissues. The present review gives an overview of analytical methods, techniques and different approaches applied to the measurement of in vivo trace metals released into body fluids and tissues from patients carrying metal-on-metal prostheses and metal dental implants. Reference levels of ion concentrations in body fluids and tissues that have been determined by a host of studies are compiled, reviewed and presented in this paper. Finally, a collection of published clinical data on in vivo released trace metals from metallic medical implants is included. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Ion implantation and ion assisted coatings for wear resistance in metals

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1986-01-01

    The implantation of electrically accelerated ions of chosen elements into the surface of material provides a method for improving surface properties such as wear resistance. High concentrations of nitrogen implanted into metals create obstacles to dislocation movement, and certain combinations of metallic and non-metallic species will also strengthen the surface. The process is best applied to situations involving mild abrasive wear and operating temperatures that are not too high. Some dramatic increases in life have been reported under such favourable conditions. A more recent development has been the combination of a thin coating with reactive ion bombardment designed to enhance adhesion by ion mixing at the interface and so provide hardness by the formation of finely dispersed nitrides, including cubic boron nitride. These coatings often possess vivid and decorative colours as an added benefit. Developments in the equipment for industrial ion implantation now offer more attractive costs per unit area and a potentially greater throughput of work. A versatile group of related hard vacuum treatments is now emerging, involving the use of intense beams of nitrogen ions for the purpose of tailoring metal surfaces to resist wear. (author)

  15. Upgraded vacuum arc ion source for metal ion implantation

    International Nuclear Information System (INIS)

    Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.; Brown, I. G.

    2012-01-01

    Vacuum arc ion sources have been made and used by a large number of research groups around the world over the past twenty years. The first generation of vacuum arc ion sources (dubbed ''Mevva,'' for metal vapor vacuum arc) was developed at Lawrence Berkeley National Laboratory in the 1980s. This paper considers the design, performance parameters, and some applications of a new modified version of this kind of source which we have called Mevva-V.Ru. The source produces broad beams of metal ions at an extraction voltage of up to 60 kV and a time-averaged ion beam current in the milliampere range. Here, we describe the Mevva-V.Ru vacuum arc ion source that we have developed at Tomsk and summarize its beam characteristics along with some of the applications to which we have put it. We also describe the source performance using compound cathodes.

  16. [The use of polymer gel dosimetry to measure dose distribution around metallic implants].

    Science.gov (United States)

    Nagahata, Tomomasa; Yamaguchi, Hajime; Monzen, Hajime; Nishimura, Yasumasa

    2014-10-01

    A semi-solid polymer dosimetry system using agar was developed to measure the dose distribution close to metallic implants. Dosimetry of heterogeneous fields where electron density markedly varies is often problematic. This prompted us to develop a polymer gel dosimetry technique using agar to measure the dose distribution near substance boundaries. Varying the concentration of an oxygen scavenger (tetra-hydroxymethyl phosphonium chloride) showed the absorbed dose and transverse relaxation rate of the magnetic resonance signal to be linear between 3 and 12 Gy. Although a change in the dosimeter due to oxidization was observed in room air after 24 hours, no such effects were observed in the first 4 hours. The dose distribution around the metal implants was measured using agar dosimetry. The metals tested were a lead rod, a titanium hip joint, and a metallic stent. A maximum 30% dose increase was observed near the lead rod, but only a 3% increase in the absorbed dose was noted near the surface of the titanium hip joint and metallic stent. Semi-solid polymer dosimetry using agar thus appears to be a useful method for dosimetry around metallic substances.

  17. The effect of therapeutic ultrasound on metallic implants: a study in rats.

    Science.gov (United States)

    Kocaoğlu, Barış; Cabukoglu, Cengiz; Ozeras, Nadire; Seyhan, Mustafa; Karahan, Mustafa; Yalcin, Selim

    2011-11-01

    To investigate whether therapeutic ultrasound (US) use over metallic implants has the potential for adverse effects as a result of greater temperature increases at the tissue-metal interface. A randomized controlled trial. A research laboratory. Sprague-Dawley rats (N=40; weight, 230-300g) were used and divided into 3 study groups. In group 1, both limbs of 10 rats were used for evaluation of temperature changes. Metal pins were placed into the femur of the left limb, and the right limbs were used as controls. A thermal sensor was placed into the medulla to record the elevation of tissue temperature during US application. In groups 2 and 3 with 15 rats in each, a midshaft femoral fracture was produced, and intramedullary fixation was performed with metal pins. Group 2 received US treatment for 5 minutes daily and continued for 27 days. Group 3 served as controls. The rats in groups 2 and 3 were killed on postoperative day 30. The specimens were evaluated by radiology, histopathology, and biomechanics. The presence of metal in bone did not cause an increased temperature rise. US application did not increase or decrease callus formation, and there was no tissue necrosis. The average removal torques of pins in groups did not show a significant difference. Internal fixation with metallic implants may not be a contraindication for therapeutic US treatment. Copyright © 2011 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  18. The use of polymer gel dosimetry to measure dose distribution around metallic implants

    International Nuclear Information System (INIS)

    Nagahata, Tomomasa; Yamaguchi, Hajime; Monzen, Hajime; Nishimura, Yasumasa

    2014-01-01

    A semi-solid polymer dosimetry system using agar was developed to measure the dose distribution close to metallic implants. Dosimetry of heterogeneous fields where electron density markedly varies is often problematic. This prompted us to develop a polymer gel dosimetry technique using agar to measure the dose distribution near substance boundaries. Varying the concentration of an oxygen scavenger (tetra-hydroxymethyl phosphonium chloride) showed the absorbed dose and transverse relaxation rate of the magnetic resonance signal to be linear between 3 and 12 Gy. Although a change in the dosimeter due to oxidization was observed in room air after 24 hours, no such effects were observed in the first 4 hours. The dose distribution around the metal implants was measured using agar dosimetry. The metals tested were a lead rod, a titanium hip joint, and a metallic stent. A maximum 30% dose increase was observed near the lead rod, but only a 3% increase in the absorbed dose was noted near the surface of the titanium hip joint and metallic stent. Semi-solid polymer dosimetry using agar thus appears to be a useful method for dosimetry around metallic substances. (author)

  19. Interaction of power pulses of laser radiation with glasses containing implanted metal nanoparticles

    CERN Document Server

    Stepanov, A L; Hole, D E; Bukharaev, A A

    2001-01-01

    The sodium-calcium silicate glasses, implanted by the Ag sup + ions with the energy of 60 keV and the dose of 7 x 10 sup 1 sup 6 cm sup - sup 2 by the ion current flux density of 10 mu A/cm sup 2 , are studied. The ion implantation makes it possible to synthesize in the near-the-surface glass area the composite layer, including the silver nanoparticles. The effect of the powerful pulse excimer laser on the obtained composite layer is investigated. It is established that the laser radiation leads to decrease in the silver nanoparticles size in the implanted layer. However nonuniform distribution of particles by size remains though not so wide as before the irradiation. The experimental results are explained by the effect of glass and metallic particles melting in the nanosecond period of time

  20. Calibration of germanium detectors

    International Nuclear Information System (INIS)

    Bjurman, B.; Erlandsson, B.

    1985-01-01

    This paper describes problems concerning the calibration of germanium detectors for the measurement of gamma-radiation from environmental samples. It also contains a brief description of some ways of reducing the uncertainties concerning the activity determination. These uncertainties have many sources, such as counting statistics, full energy peak efficiency determination, density correction and radionuclide specific-coincidence effects, when environmental samples are investigated at close source-to-detector distances

  1. Usefulness of CT angiography after metallic stent implantation of the internal carotid artery

    International Nuclear Information System (INIS)

    Yoon, Man Won; Kim, Hyeon Chul; Kim, Jae Kyu; Seo, Jeong Jin; Jeong, Gwang Woo; Kang, Heoung Keun

    1999-01-01

    To evaluate the usefulness of CT angiography in patients with implantation of metallic stent for stenosed internal carotid artery. Seven patients with atherosclerotic stenosis of the internal carotid artery underwent metallic stent implantation. All were male and their ages ranged from 36 to 69 years. A total of seven stents were placed in the internal carotid artery in five patients and in the carotid bifurcation in two. Spiral CT scans were obtained and CT angiographic images were reconstructed using MPR or curved MPR techniques at a workstation. The interval between CT and conventional angiography did not exceed six days except in one patient, in whom it was 61days. CT and conventional angiography were compared for stent position with respect to the carotid bifurcation, stent deformation, intraluminal filling defect, and luminal caliber and outflow. Luminal patency of the implanted stent was measured according to NASCET(North American Symptomatic Carotid Endarterectomy Trial) criteria, and statistically processed (p>.05). The presence or absence of intrastent thrombus and vascular wall calcification was determined using axial source images. In all patients, CT angiographic findings matched those obtained by conventional angiography. Complications such as migration or deformation of an implanted stent, intraluminal filling defect, change of luminal caliber or outflow of implanted stent were not observed in any patient. In two studies in which Wilcoxon signed rank test was used, degree of stent expansion correlated closely(p=0.237). Axial source images showed that in no patient was an intrastent thrombus present, though in five, vascular wall calcification of internal carotid arteries outside the stent was noted. CT angiography is useful for the assessment of positional change, occlusion, and luminal patency of a stent-implanted internal carotid artery

  2. Osseointegration and biocompatibility of different metal implants - a comparative experimental investigation in sheep

    Science.gov (United States)

    2012-01-01

    Background In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep. Methods Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically. Results Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials. Conclusion This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior. PMID:22400715

  3. Effect of carbon ion implantation on the tribology of metal-on-metal bearings for artificial joints

    Directory of Open Access Journals (Sweden)

    Koseki H

    2017-05-01

    Full Text Available Hironobu Koseki,1 Masato Tomita,2 Akihiko Yonekura,2 Takashi Higuchi,1 Sinya Sunagawa,2 Koumei Baba,3,4 Makoto Osaki2 1Department of Locomotive Rehabilitation Science, Unit of Rehabilitation Sciences, 2Department of Orthopedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto, Nagasaki, Japan; 3Industrial Technology Center of Nagasaki, Ikeda, Omura, Nagasaki, Japan; 4Affiliated Division, Nagasaki University School of Engineering, Bunkyo, Nagasaki, Japan Abstract: Metal-on-metal (MoM bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa, a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and

  4. Bone response to a titanium aluminium nitride coating on metallic implants.

    Science.gov (United States)

    Freeman, C O; Brook, I M

    2006-05-01

    The design, surface characteristics and strength of metallic implants are dependant on their intended use and clinical application. Surface modifications of materials may enable reduction of the time taken for osseointegration and improve the biological response of bio-mechanically favourable metals and alloys. The influence of a titanium aluminium nitride (TAN) coating on the response of bone to commercially pure titanium and austenitic 18/8 stainless steel wire is reported. TAN coated and plain rods of stainless steel and commercially pure titanium were implanted into the mid-shaft of the femur of Wistar rats. The femurs were harvested at four weeks and processed for scanning electron and light microscopy. All implants exhibited a favourable response in bone with no evidence of fibrous encapsulation. There was no significant difference in the amount of new bone formed around the different rods (osseoconduction), however, there was a greater degree of shrinkage separation of bone from the coated rods than from the plain rods (p = 0.017 stainless steel and p = 0.0085 titanium). TAN coating may result in reduced osseointegration between bone and implant.

  5. Influence of metal artifacts on in vivo micro-CT for orthodontic mini-implants

    International Nuclear Information System (INIS)

    Ejima, Ken-ichiro; Omasa, Saori; Motoyoshi, Mitsuru; Arai, Yoshinori; Kai, Yukiko; Amemiya, Toshihiko; Yamada, Hisaya; Honda, Kazuya; Shimizu, Noriyoshi

    2012-01-01

    This study aimed to show the effects of metal artifacts on the in vivo micro-CT of mini-implants by measuring bone volume. We drilled a hole in the cortical bone of a rat tibia and embedded a titanium orthodontic mini-implant (diameter, 1.5 mm) in the hole. Twelve individually weighed hydroxyapatite grains (HA grains) were placed around the implant either by one dentist (method 1) or separately by 12 dentists (method 2). In vivo micro-CT was used to scan the model after placement of each grain to measure increases and decreases in bone volume voxel number. The subtracted bone voxel volume increased with HA weight in both methods. Simple linear regression analysis showed a significant correlation between weight and volume in both methods (method 1: regression coefficient: 516.502, P<0.05; method 2: regression coefficient: 4837.432, P<0.05). Metal artifacts did not appear to influence measurements of bone volume, although further studies are required to determine the effect of thicker implants. (author)

  6. The fabrication of metal silicide nanodot arrays using localized ion implantation

    International Nuclear Information System (INIS)

    Han, Jin; Kim, Tae-Gon; Min, Byung-Kwon; Lee, Sang Jo

    2010-01-01

    We propose a process for fabricating nanodot arrays with a pitch size of less than 25 nm. The process consists of localized ion implantation in a metal thin film on a Si wafer using a focused ion beam (FIB), followed by chemical etching. This process utilizes the etching resistivity changes of the ion beam irradiated region that result from metal silicide formation by ion implantation. To control the nanodot diameter, a threshold ion dose model is proposed using the Gaussian distribution of the ion beam intensities. The process is verified by fabricating nanodots with various diameters. The mechanism of etching resistivity is investigated via x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES).

  7. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    Science.gov (United States)

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  8. Metallic oxide nano-clusters synthesis by ion implantation in high purity Fe10Cr alloy

    International Nuclear Information System (INIS)

    Zheng, Ce

    2015-01-01

    ODS (Oxide Dispersed Strengthened) steels, which are reinforced with metal dispersions of nano-oxides (based on Y, Ti and O elements), are promising materials for future nuclear reactors. The detailed understanding of the mechanisms involved in the precipitation of these nano-oxides would improve manufacturing and mechanical properties of these ODS steels, with a strong economic impact for their industrialization. To experimentally study these mechanisms, an analytical approach by ion implantation is used, to control various parameters of synthesis of these precipitates as the temperature and concentration. This study demonstrated the feasibility of this method and concerned the behaviour of alloys models (based on aluminium oxide) under thermal annealing. High purity Fe-10Cr alloys were implanted with Al and O ions at room temperature. Transmission electron microscopy observations showed that the nano-oxides appear in the Fe-10Cr matrix upon ion implantation at room temperature without subsequent annealing. The mobility of implanted elements is caused by the defects created during ion implantation, allowing the nucleation of these nanoparticles, of a few nm in diameter. These nanoparticles are composed of aluminium and oxygen, and also chromium. The high-resolution experiments show that their crystallographic structure is that of a non-equilibrium compound of aluminium oxide (cubic γ-Al 2 O 3 type). The heat treatment performed after implantation induces the growth of the nano-sized oxides, and a phase change that tends to balance to the equilibrium structure (hexagonal α-Al 2 O 3 type). These results on model alloys are fully applicable to industrial materials: indeed ion implantation reproduces the conditions of milling and heat treatments are at equivalent temperatures to those of thermo-mechanical treatments. A mechanism involving the precipitation of nano-oxide dispersed in ODS alloys is proposed in this manuscript based on the obtained experimental results

  9. Fabrication and characterisation of embedded metal nanostructures by ion implantation with nanoporous anodic alumina masks

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Wei [NanoLAB, Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom); Peng, Nianhua, E-mail: n.peng@surrey.ac.uk [Surrey Ion Beam Centre, Surrey University, Guildford GU2 7XH (United Kingdom); Jeynes, Christopher [Surrey Ion Beam Centre, Surrey University, Guildford GU2 7XH (United Kingdom); Ghatak, Jay [NanoLAB, Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Peng, Yong [NanoLAB, Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); School of Physical Science and Technology, Lanzhou University, 222 Tianshui Road, Lanzhou 730000 (China); Ross, Ian M. [Department of Electronic and Electric Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Bhatta, Umananda M.; Inkson, Beverley J.; Möbus, Günter [NanoLAB, Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2013-07-15

    Lateral ordered Co, Pt and Co/Pt nanostructures were fabricated in SiO{sub 2} and Si{sub 3}N{sub 4} substrates by high fluence metal ion implantation through periodic nanochannel membrane masks based on anodic aluminium oxides (AAO). The quality of nanopatterning transfer defined by various AAO masks in different substrates was examined by transmission electron microscopy (TEM) in both imaging and spectroscopy modes.

  10. Implanted cardiac devices are reliably detected by commercially available metal detectors

    DEFF Research Database (Denmark)

    Holm, Katja Fiedler; Hjortshøj, Søren Pihlkjær; Pehrson, Steen

    2013-01-01

    Explosions of Cardiovascular Implantable Electronic Devices (CIEDs) (pacemakers, defibrillators, and loop recorders) are a well-recognized problem during cremation, due to lithium-iodine batteries. In addition, burial of the deceased with a CIED can present a potential risk for environmental...... contamination. Therefore, detection of CIEDs in the deceased would be of value. This study evaluated a commercially available metal detector for detecting CIEDs....

  11. The structural and optical properties of metal ion-implanted GaN

    Czech Academy of Sciences Publication Activity Database

    Macková, Anna; Malinský, Petr; Sofer, Z.; Šimek, P.; Sedmidubský, D.; Veselý, M.; Bottger, R.

    2016-01-01

    Roč. 371, MAR (2016), s. 254-257 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR GA15-01602S Institutional support: RVO:61389005 Keywords : RBS channelling * metal-implanted GaN * structural changes Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  12. Effect of carbon ion implantation on the tribology of metal-on-metal bearings for artificial joints.

    Science.gov (United States)

    Koseki, Hironobu; Tomita, Masato; Yonekura, Akihiko; Higuchi, Takashi; Sunagawa, Sinya; Baba, Koumei; Osaki, Makoto

    2017-01-01

    Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses.

  13. Magnetic properties of thin films obtained by ion implantation of 3d metals in polyethylene-terephthalate

    International Nuclear Information System (INIS)

    Petukhov, V.Yu.; Ibragimova, M.I.; Khabibullina, N.R; Zheglov, E.P.; Muller, R.

    2002-01-01

    Polymer films containing small metal particles have been attracting particular interest because of their unique properties. Implantation of metal ions in polymers is one of the methods to synthesize metal-polymer nano-composite materials. Ion implantation makes possible the magnetic nano-structures with controlled parameters. Previously, we showed that 3d-metal implantation into numerous polymers (polymethylmethacrylate, phosphorus containing polymethylmethacrylate) resulted in the formation of a composite film consisting of metal nanoparticles buried in an implanted layer. The particles are usually found to be distributed randomly in the surface layer. It has been established that structural peculiarities, phase composition, and magnetic properties of synthesized metal-polymer systems depend on the type of the initial polymer matrix, ion types, as well as conditions of ion implantation. In the present study we have been prepared thin metal-polymer composite films by ion-beam implantation of Fe + and Co + ions in polyethylene terephthalate. The implantation of 40 keV ions at room temperature with doses from 2·10 1 6 to 3·10 17 cm -2 have been performed, with the ion current density not exceeding 10 μA/cm 2 . The magnetic properties have been investigated both by ferromagnetic resonance (FMR) and vibrating sample magnetometry (VSM). FMR spectra were recorded using magnetic radio spectrometer Varian E-12 with frequency of 9.5 GHz at room temperature. The dependencies of FMR spectra on orientation have been measured for all samples. Measurements were carried out for two orientations of the sample, normal direction of the films being either parallel or perpendicular to dc magnetic field. The values of the effective magnetization were calculated from orientation dependencies. Thin ferromagnetic films (TFF) have been shown to form for samples with both implanted ions. For samples implanted with Co + ions, the appearance of FMR lines occurs at doses markedly greater

  14. Improving Passivation Process of Si Nano crystals Embedded in SiO2 Using Metal Ion Implantation

    International Nuclear Information System (INIS)

    Bornacelli, J.; Esqueda, J.A.R.; Fernandez, L.R.; Oliver, A.

    2013-01-01

    We studied the photoluminescence (PL) of Si nano crystals (Si-NCs) embedded in SiO 2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm) inside the SiO 2 achieving a robust and better protected system. After metal ion implantation (Ag or Au), and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs) could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO 2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H 2 /N 2 and Ar) to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  15. Zirconia- versus metal-based, implant-supported abutments and crowns

    DEFF Research Database (Denmark)

    Hosseini, Mandana

    , the selection of restoration materials should be based on proper optical characteristics in addition to biocompatibility and sufficient strength of materials. Abutments and crowns based on zirconia are one of the most recent alternatives to metal abutments and metal-ceramic crowns. To date, only few comparative...... and to estimate long-term biomechanical results of zirconia-based versus metal-based restorations. The aim of study I was to analyse the mode of fracture and number of cyclic loadings until veneering fracture of zirconia-based all-ceramic restorations compared to metal-ceramic restorations. The aim of study II...... was to test the reliability and validity of six aesthetic parameters used at the Copenhagen Dental School to assess the aesthetic outcome of implant-supported restorations. The aims of study III and IV were to compare the influence of different abutment and crown materials on biological, biomechanical...

  16. Repair of olecranon fractures using fiberWire without metallic implants: report of two cases

    Directory of Open Access Journals (Sweden)

    Okawa Atsushi

    2010-10-01

    Full Text Available Abstract Olecranon fractures are a common injury in fractures. The tension band technique for olecranon fractures yields good clinical outcomes; however, it is associated with significant complications. In many patients, implants irritate overlying soft tissues and cause pain. This is mostly due to protrusion of the proximal ends of the K-wires or by the twisted knots of the metal wire tension band. Below we described 2 cases of olecranon fractures treated with a unique technique using FiberWire without any metallic implants. Technically, the fragment was reduced, and two K-wires were inserted from the dorsal cortex of the distal segment to the tip of the olecranon. K-wire was exchanged for a suture retriever, and 2 strands of FiberWire were retrieved twice. Each of the two FiberWires was manually tensioned and knotted on the posterior surface of the olecranon. Bony unions could be achieved, and patients had no complaint of pain and skin irritation. There was only a small loss of flexion and extension in comparison with that of the contralateral side, and the patient did not feel inconvenienced in his daily life. Using the method described, difficulty due to K-wire or other metallic implants was avoided.

  17. Repair of olecranon fractures using fiberWire without metallic implants: report of two cases.

    Science.gov (United States)

    Nimura, Akimoto; Nakagawa, Teruhiko; Wakabayashi, Yoshiaki; Sekiya, Ichiro; Okawa, Atsushi; Muneta, Takeshi

    2010-10-12

    Olecranon fractures are a common injury in fractures. The tension band technique for olecranon fractures yields good clinical outcomes; however, it is associated with significant complications. In many patients, implants irritate overlying soft tissues and cause pain. This is mostly due to protrusion of the proximal ends of the K-wires or by the twisted knots of the metal wire tension band. Below we described 2 cases of olecranon fractures treated with a unique technique using FiberWire without any metallic implants. Technically, the fragment was reduced, and two K-wires were inserted from the dorsal cortex of the distal segment to the tip of the olecranon. K-wire was exchanged for a suture retriever, and 2 strands of FiberWire were retrieved twice. Each of the two FiberWires was manually tensioned and knotted on the posterior surface of the olecranon. Bony unions could be achieved, and patients had no complaint of pain and skin irritation. There was only a small loss of flexion and extension in comparison with that of the contralateral side, and the patient did not feel inconvenienced in his daily life. Using the method described, difficulty due to K-wire or other metallic implants was avoided.

  18. Current practices in corrosion, surface characterization, and nickel leach testing of cardiovascular metallic implants.

    Science.gov (United States)

    Nagaraja, Srinidhi; Di Prima, Matthew; Saylor, David; Takai, Erica

    2017-08-01

    In an effort to better understand current test practices and improve nonclinical testing of cardiovascular metallic implants, the Food and Drug Administration (FDA) held a public workshop on Cardiovascular Metallic Implants: corrosion, surface characterization, and nickel leaching. The following topics were discussed: (1) methods used for corrosion assessments, surface characterization techniques, and nickel leach testing of metallic cardiovascular implant devices, (2) the limitations of each of these in vitro tests in predicting in vivo performance, (3) the need, utility, and circumstances when each test should be considered, and (4) the potential testing paradigms, including acceptance criteria for each test. In addition to the above topics, best practices for these various tests were discussed, and knowledge gaps were identified. Prior to the workshop, discussants had the option to provide feedback and information on issues relating to each of the topics via a voluntary preworkshop assignment. During the workshop, the pooled responses were presented and a panel of experts discussed the results. This article summarizes the proceedings of this workshop and background information provided by workshop participants. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. J Biomed Mater Res Part B: Appl Biomater, 105B: 1330-1341, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  19. Quality assurance: recommended guidelines for safe heating by capacitive-type heating technique to treat patients with metallic implants.

    Science.gov (United States)

    Kato, Hirokazu; Kondo, Motoharu; Imada, Hajime; Kuroda, Masahiro; Kamimura, Yoshitsugu; Saito, Kazuyuki; Kuroda, Kagayaki; Ito, Koichi; Takahashi, Hideaki; Matsuki, Hidetoshi

    2013-05-01

    This article is a redissemination of the previous Japanese Quality Assurance Guide guidelines. Specific absorption rate and temperature distribution were investigated with respect to various aspects including metallic implant size and shape, insertion site, insertion direction, blood flow and heating power, and simulated results were compared with adverse reactions of patients treated by radio frequency capacitive-type heating. Recommended guidelines for safe heating methods for patients with metallic implants are presented based on our findings.

  20. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants.

    Science.gov (United States)

    Ahlawat, Shivani; Stern, Steven E; Belzberg, Allan J; Fritz, Jan

    2017-07-01

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips.

  1. Custom-made, root-analogue direct laser metal forming implant: a case report.

    Science.gov (United States)

    Mangano, Francesco Guido; Cirotti, Bruno; Sammons, Rachel Lilian; Mangano, Carlo

    2012-11-01

    In the last few years, the application of digital technology in dentistry has become widespread with the introduction of cone beam computed tomography (CBCT) scan technology, and considerable progress has been made in the development of computer-aided design/ computer-aided manufacturing (CAD/CAM) techniques, including direct laser metal forming (DLMF). DLMF is a technology which allows solids with complex geometry to be produced by annealing metal powder microparticles in a focused laser beam, according to a computer-generated three-dimensional (3D) model. For dental implants, the fabrication process involves the laser-induced fusion of titanium microparticles, in order to build, layer by layer, the desired object. At present, the combined use of CBCT 3D data and CAD/CAM technology makes it possible to manufacture custom-made, root-analogue implants (RAI) with sufficient precision. This report demonstrates the successful clinical use of a custom-made, root-analogue DLMF implant. CBCT images of a non-restorable right maxillary first premolar were acquired and transformed into a 3D model. From this model, a custom-made, root-analogue DLMF implant was fabricated. Immediately after tooth extraction, the RAI with a pre-operatively designed abutment was placed in the extraction socket and restored with a single crown. At the 1-year follow-up examination, the RAI showed a good functional and aesthetic integration. The introduction of DLMF technology signals the start of a new revolutionary era for implant dentistry as its immense potential for producing highly complex macro- and microstructures is receiving vast interest in different medical fields.

  2. Histological Evidence of the Osseointegration of Fractured Direct Metal Laser Sintering Implants Retrieved after 5 Years of Function

    Directory of Open Access Journals (Sweden)

    Francesco Mangano

    2017-01-01

    Full Text Available Background. Direct metal laser sintering (DMLS is an additive manufacturing technique that allows the fabrication of dental implants layer by layer through the laser fusion of titanium microparticles. The surface of DMLS implants is characterized by a high open porosity with interconnected pores of different sizes; therefore, it has the potential to enhance and accelerate bone healing. To date, however, there are no histologic/histomorphometric studies in the literature evaluating the interface between bone and DMLS implants in the long-term. Purpose. To evaluate the interface between bone and DMLS implants retrieved after 5 years of functional loading. Methods. Two fractured DMLS implants were retrieved from the human jaws, using a 5 mm trephine bur. Both the implants were clinically stable and functioned regularly before fracture. The specimens were processed for histologic/histomorphometric evaluation; the bone-to-implant contact (BIC% was calculated. Results. Compact, mature lamellar bone was found over most of the DMLS implants in close contact with the implant surface; the histomorphometric evaluation showed a mean BIC% of 66.1% (±4.5%. Conclusions. The present histologic/histomorphometric study showed that DMLS implants were well integrated in bone, after 5 years of loading, with the peri-implant bone undergoing continuous remodeling at the interface.

  3. Histological Evidence of the Osseointegration of Fractured Direct Metal Laser Sintering Implants Retrieved after 5 Years of Function

    Science.gov (United States)

    Piattelli, Adriano

    2017-01-01

    Background Direct metal laser sintering (DMLS) is an additive manufacturing technique that allows the fabrication of dental implants layer by layer through the laser fusion of titanium microparticles. The surface of DMLS implants is characterized by a high open porosity with interconnected pores of different sizes; therefore, it has the potential to enhance and accelerate bone healing. To date, however, there are no histologic/histomorphometric studies in the literature evaluating the interface between bone and DMLS implants in the long-term. Purpose To evaluate the interface between bone and DMLS implants retrieved after 5 years of functional loading. Methods Two fractured DMLS implants were retrieved from the human jaws, using a 5 mm trephine bur. Both the implants were clinically stable and functioned regularly before fracture. The specimens were processed for histologic/histomorphometric evaluation; the bone-to-implant contact (BIC%) was calculated. Results Compact, mature lamellar bone was found over most of the DMLS implants in close contact with the implant surface; the histomorphometric evaluation showed a mean BIC% of 66.1% (±4.5%). Conclusions The present histologic/histomorphometric study showed that DMLS implants were well integrated in bone, after 5 years of loading, with the peri-implant bone undergoing continuous remodeling at the interface. PMID:28929117

  4. Histological Evidence of the Osseointegration of Fractured Direct Metal Laser Sintering Implants Retrieved after 5 Years of Function.

    Science.gov (United States)

    Mangano, Francesco; Mangano, Carlo; Piattelli, Adriano; Iezzi, Giovanna

    2017-01-01

    Direct metal laser sintering (DMLS) is an additive manufacturing technique that allows the fabrication of dental implants layer by layer through the laser fusion of titanium microparticles. The surface of DMLS implants is characterized by a high open porosity with interconnected pores of different sizes; therefore, it has the potential to enhance and accelerate bone healing. To date, however, there are no histologic/histomorphometric studies in the literature evaluating the interface between bone and DMLS implants in the long-term. To evaluate the interface between bone and DMLS implants retrieved after 5 years of functional loading. Two fractured DMLS implants were retrieved from the human jaws, using a 5 mm trephine bur. Both the implants were clinically stable and functioned regularly before fracture. The specimens were processed for histologic/histomorphometric evaluation; the bone-to-implant contact (BIC%) was calculated. Compact, mature lamellar bone was found over most of the DMLS implants in close contact with the implant surface; the histomorphometric evaluation showed a mean BIC% of 66.1% (±4.5%). The present histologic/histomorphometric study showed that DMLS implants were well integrated in bone, after 5 years of loading, with the peri-implant bone undergoing continuous remodeling at the interface.

  5. Studies on the surface modification of TiN coatings using MEVVA ion implantation with selected metallic species

    International Nuclear Information System (INIS)

    Ward, L.P.; Purushotham, K.P.; Manory, R.R.

    2016-01-01

    Highlights: • Reduced surface roughness was observed after ion implantation. • W implantation increased residual stress. • Reduced friction and wear accompanied Mo implantation. • Mo implanted layer was more resistant to breakdown during wear testing. • Ion implantation effects can be complex on various implanting species properties. - Abstract: Improvement in the performance of TiN coatings can be achieved using surface modification techniques such as ion implantation. In the present study, physical vapor deposited (PVD) TiN coatings were implanted with Cr, Zr, Nb, Mo and W using the metal evaporation vacuum arc (MEVVA) technique at a constant nominal dose of 4 × 10 16 ions cm −2 for all species. The samples were characterized before and after implantation, using Rutherford backscattering (RBS), glancing incident angle X-ray diffraction (GIXRD), atomic force microscopy (AFM) and optical microscopy. Friction and wear studies were performed under dry sliding conditions using a pin-on-disc CSEM Tribometer at 1 N load and 450 m sliding distance. A reduction in the grain size and surface roughness was observed after implantation with all five species. Little variation was observed in the residual stress values for all implanted TiN coatings, except for W implanted TiN which showed a pronounced increase in compressive residual stress. Mo-implanted samples showed a lower coefficient of friction and higher resistance to breakdown during the initial stages of testing than as-received samples. Significant reduction in wear rate was observed after implanting with Zr and Mo ions compared with unimplanted TiN. The presence of the Ti 2 N phase was observed with Cr implantation.

  6. Retentiveness of implant-supported metal copings using different luting agents

    Directory of Open Access Journals (Sweden)

    Farahnaz Nejatidanesh

    2012-01-01

    Full Text Available Background: With regard to potential retrievability of cement-retained implant restorations, the retentive strength of the luting agents is critical. The aim of this study was to evaluate the retention values of implant-supported metal copings using different luting agents. Materials and Methods: Twenty ITI implant analogs and solid abutments of 5.5-mm height were embedded vertically in autopolymerizing acrylic resin blocks. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III. The copings were luted using eight cements with different retention mechanisms (Panavia F2.0, Fuji Plus, Fleck′s, Poly F, Fuji I, Temp Bond, GC-free eugenol, and TempSpan under static load of 5 kg (n=10. All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days and thermocycled for 5000 cycles (5-55°C. The dislodging force was measured using a universal testing machine at a crosshead speed of 5 mm/min. Statistical analyses were performed using Kruskal-Wallis (α=0.05 and Mann-Whitney tests with Bonferroni correction (α=0.001. Results: Fuji Plus and TempSpan had the highest and the least mean retentive strength, respectively (320.97±161.47, 3.39±2.33. There was no significant difference between Fuji Plus, Fleck′s, Ploy F, and Panavia F2.0. These cements were superior to provisional cements and Fuji I (P<0.001 which showed statistically same retentive strength. Conclusion: Within the conditions of this study, the resin modified glass ionomer, zinc phosphate, zinc polycarboxylate, and Panavia F2.0 had statistically the same retentive quality and are recommended for definitive cementation of single implant-supported restorations. The provisional cements and glass ionomer may allow retrievability of these restorations.

  7. Cartilage Health in Knees Treated with Metal Resurfacing Implants or Untreated Focal Cartilage Lesions: A Preclinical Study in Sheep.

    Science.gov (United States)

    Martinez-Carranza, Nicolas; Hultenby, Kjell; Lagerstedt, Anne Sofie; Schupbach, Peter; Berg, Hans E

    2017-07-01

    Background Full-depth cartilage lesions do not heal and the long-term clinical outcome is uncertain. In the symptomatic middle-aged (35-60 years) patient, treatment with metal implants has been proposed. However, the cartilage health surrounding these implants has not been thoroughly studied. Our objective was to evaluate the health of cartilage opposing and adjacent to metal resurfacing implants. Methods The medial femoral condyle was operated in 9 sheep bilaterally. A metallic resurfacing metallic implant was immediately inserted into an artificially created 7.5 mm defect while on the contralateral knee the defect was left untreated. Euthanasia was performed at 6 months. Six animals, of similar age and study duration, from a previous study were used for comparison in the evaluation of cartilage health adjacent to the implant. Cartilage damage to joint surfaces within the knee, cartilage repair of the defect, and cartilage adjacent to the implant was evaluated macroscopically and microscopically. Results Six animals available for evaluation of cartilage health within the knee showed a varying degree of cartilage damage with no statistical difference between defects treated with implants or left untreated ( P = 0.51; 95% CI -3.7 to 6.5). The cartilage adjacent to the implant (score 0-14; where 14 indicates no damage) remained healthy in these 6 animals showing promising results (averaged 10.5; range 9-11.5, SD 0.95). Cartilage defects did not heal in any case. Conclusion Treatment of a critical size focal lesion with a metal implant is a viable alternative treatment.

  8. Modification of WC-Co Hard Metal by Ion Implantation with Ti+, AI+, N+, C+ and B+

    International Nuclear Information System (INIS)

    Rassoul, El.M.A.; Saleh, Z.A.; Waheed, A.F.; Abdel- Samad, S.M.; EI- Awadi, G.A.

    2010-01-01

    WC/Co hard metal was implanted by Ti + , AI + , N + , C + , and B + ions at a dose of 5x 10 17 ions/cm 2 at different energies ranging from 50 keV to 200 keV. The implanted layers were investigated by means of nano indentation, calotte measurements, SEM, X-ray diffraction XRD, tribometer and EDX. The maximum implanted zone was about 0.13 μm. The hardness of WC-Co was increased by a factor of 140% after its implantation by Ti, AI, and N and increased by a factor of 170 % after implantation by Ti + , AI + , C + , N + and B + ions as compared to the original value. Also friction coefficient of WC/Co was improved after ion implantation.

  9. Multi-scale modification of metallic implants with pore gradients, polyelectrolytes and their indirect monitoring in vivo.

    Science.gov (United States)

    Vrana, Nihal E; Dupret-Bories, Agnes; Chaubaroux, Christophe; Rieger, Elisabeth; Debry, Christian; Vautier, Dominique; Metz-Boutigue, Marie-Helene; Lavalle, Philippe

    2013-07-01

    Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modifications using porous titanium implants based on titanium microbeads. By using inherent physical properties such as hydrophobicity of titanium, it is possible to obtain hydrophobic pore gradients within microbead based metallic implants and at the same time to have a basement membrane mimic based on hydrophilic, natural polymers. 3D pore gradients are formed by synthetic polymers such as Poly-L-lactic acid (PLLA) by freeze-extraction method. 2D nanofibrillar surfaces are formed by using collagen/alginate followed by a crosslinking step with a natural crosslinker (genipin). This nanofibrillar film was built up by layer by layer (LbL) deposition method of the two oppositely charged molecules, collagen and alginate. Finally, an implant where different areas can accommodate different cell types, as this is necessary for many multicellular tissues, can be obtained. By, this way cellular movement in different directions by different cell types can be controlled. Such a system is described for the specific case of trachea regeneration, but it can be modified for other target organs. Analysis of cell migration and the possible methods for creating different pore gradients are elaborated. The next step in the analysis of such implants is their characterization after implantation. However, histological analysis of metallic implants is a long and cumbersome process, thus for monitoring host reaction to metallic implants in vivo an alternative method based on monitoring CGA and different

  10. Dose perturbation in the presence of metallic implants: treatment planning system versus Monte Carlo simulations

    International Nuclear Information System (INIS)

    Wieslander, Elinore; Knoeoes, Tommy

    2003-01-01

    An increasing number of patients receiving radiation therapy have metallic implants such as hip prostheses. Therefore, beams are normally set up to avoid irradiation through the implant; however, this cannot always be accomplished. In such situations, knowledge of the accuracy of the used treatment planning system (TPS) is required. Two algorithms, the pencil beam (PB) and the collapsed cone (CC), are implemented in the studied TPS. Comparisons are made with Monte Carlo simulations for 6 and 18 MV. The studied materials are steel, CoCrMo, Orthinox(a stainless steel alloy and registered trademark of Stryker Corporation), TiAlV and Ti. Monte Carlo simulated depth dose curves and dose profiles are compared to CC and PB calculated data. The CC algorithm shows overall a better agreement with Monte Carlo than the PB algorithm. Thus, it is recommended to use the CC algorithm to get the most accurate dose calculation both for the planning target volume and for tissues adjacent to the implants when beams are set up to pass through implants

  11. Nano-size metallic oxide particle synthesis in Fe-Cr alloys by ion implantation

    Science.gov (United States)

    Zheng, C.; Gentils, A.; Ribis, J.; Borodin, V. A.; Delauche, L.; Arnal, B.

    2017-10-01

    Oxide Dispersion Strengthened (ODS) steels reinforced with metal oxide nanoparticles are advanced structural materials for nuclear and thermonuclear reactors. The understanding of the mechanisms involved in the precipitation of nano-oxides can help in improving mechanical properties of ODS steels, with a strong impact for their commercialization. A perfect tool to study these mechanisms is ion implantation, where various precipitate synthesis parameters are under control. In the framework of this approach, high-purity Fe-10Cr alloy samples were consecutively implanted with Al and O ions at room temperature and demonstrated a number of unexpected features. For example, oxide particles of a few nm in diameter could be identified in the samples already after ion implantation at room temperature. This is very unusual for ion beam synthesis, which commonly requires post-implantation high-temperature annealing to launch precipitation. The observed particles were composed of aluminium and oxygen, but additionally contained one of the matrix elements (chromium). The crystal structure of aluminium oxide compound corresponds to non-equilibrium cubic γ-Al2O3 phase rather than to more common corundum. The obtained experimental results together with the existing literature data give insight into the physical mechanisms involved in the precipitation of nano-oxides in ODS alloys.

  12. Optimized protocols for cardiac magnetic resonance imaging in patients with thoracic metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Olivieri, Laura J.; Ratnayaka, Kanishka [Children' s National Health System, Division of Cardiology, Washington, DC (United States); National Institutes of Health, National Heart, Lung and Blood Institute, Bethesda, MD (United States); Cross, Russell R.; O' Brien, Kendall E. [Children' s National Health System, Division of Cardiology, Washington, DC (United States); Hansen, Michael S. [National Institutes of Health, National Heart, Lung and Blood Institute, Bethesda, MD (United States)

    2015-09-15

    Cardiac magnetic resonance (MR) imaging is a valuable tool in congenital heart disease; however patients frequently have metal devices in the chest from the treatment of their disease that complicate imaging. Methods are needed to improve imaging around metal implants near the heart. Basic sequence parameter manipulations have the potential to minimize artifact while limiting effects on image resolution and quality. Our objective was to design cine and static cardiac imaging sequences to minimize metal artifact while maintaining image quality. Using systematic variation of standard imaging parameters on a fluid-filled phantom containing commonly used metal cardiac devices, we developed optimized sequences for steady-state free precession (SSFP), gradient recalled echo (GRE) cine imaging, and turbo spin-echo (TSE) black-blood imaging. We imaged 17 consecutive patients undergoing routine cardiac MR with 25 metal implants of various origins using both standard and optimized imaging protocols for a given slice position. We rated images for quality and metal artifact size by measuring metal artifact in two orthogonal planes within the image. All metal artifacts were reduced with optimized imaging. The average metal artifact reduction for the optimized SSFP cine was 1.5+/-1.8 mm, and for the optimized GRE cine the reduction was 4.6+/-4.5 mm (P < 0.05). Quality ratings favored the optimized GRE cine. Similarly, the average metal artifact reduction for the optimized TSE images was 1.6+/-1.7 mm (P < 0.05), and quality ratings favored the optimized TSE imaging. Imaging sequences tailored to minimize metal artifact are easily created by modifying basic sequence parameters, and images are superior to standard imaging sequences in both quality and artifact size. Specifically, for optimized cine imaging a GRE sequence should be used with settings that favor short echo time, i.e. flow compensation off, weak asymmetrical echo and a relatively high receiver bandwidth. For static

  13. Immobilization of krypton in a metallic matrix by combined ion implantation and sputtering

    International Nuclear Information System (INIS)

    Whitmell, D.S.

    1980-01-01

    With the increase in nuclear power, it may be necessary to contain for 100 to 200 years the radioactive 85 krypton released during fuel reprocessing. The ideal method of immobilizing radioactive materials is in the form of stable, monolithic solids which are resistant to the effects of the environment or accidents, and which can retain the radioactivity under all envisaged conditions. Since krypton is a rare gas, not forming thermally stable compounds, conventional methods of storage are not possible. A process is being developed to immobilize the krypton in the form of small gas bubbles in a metal matrix by implanting the gas into a metal layer from a glow discharge and then burying the implanted layer by sputter deposition. By repeating the process, a thick layer of deposit is built up with the krypton dispersed throughout the matrix as bubbles of diameter less than 20 A. This process offers an ideal form of storage since gas in bubbles is not thermally released until the temperature of the matrix is close to the melting point, and also leakage of gas by corrosion or mechanical damage will be small. A pilot plant is being built in order to demonstrate the process on a scale comparable with that required for a reprocessing plant. The efficiency of the process is dependent upon the amount of gas which can be implanted at low energy into a thin layer and its subsequent retention. (author)

  14. High Precision Metal Thin Film Liftoff Technique

    Science.gov (United States)

    Brown, Ari D. (Inventor); Patel, Amil A. (Inventor)

    2015-01-01

    A metal film liftoff process includes applying a polymer layer onto a silicon substrate, applying a germanium layer over the polymer layer to create a bilayer lift off mask, applying a patterned photoresist layer over the germanium layer, removing an exposed portion of the germanium layer, removing the photoresist layer and a portion of the polymer layer to expose a portion of the substrate and create an overhanging structure of the germanium layer, depositing a metal film over the exposed portion of the substrate and the germanium layer, and removing the polymer and germanium layers along with the overlaying metal film.

  15. Implantable polymer/metal thin film structures for the localized treatment of cancer by Joule heating

    Science.gov (United States)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Theriault, Christian; Soboyejo, Wole

    2015-04-01

    This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The predictions are also compared to prior results from in vitro studies and relevant in vivo studies in the literature. The implications of the results are discussed for the potential application of polymer/metal thin film structures in hyperthermic treatment of cancer.

  16. Perturbation of cobalt 60 radiation doses by metal objects implanted during oral and maxillofacial surgery

    International Nuclear Information System (INIS)

    Tatcher, M.; Kuten, A.; Helman, J.; Laufer, D.

    1984-01-01

    The influence on cobalt 60 dose distributions of typical metal parts used in oral and maxillofacial surgery was studied. Relative doses were determined by exposing x-ray films in a polystyrene phantom set-up containing samples of vitallium, titanium, and stainless steel. Optical densities were converted to doses with the aid of sensitometric curves. The results show that for normal incidence there is a 25% to 40% increase in dose at the entrance side of the metal and a 20% to 25% decrease in dose at the exit side. The enhancement effect falls off rapidly and becomes negligible at about 1 mm from the interface. The reduction effect decreases more gradually and is still evident at distances of a few centimeters. These dose perturbations should be taken into account in the planning of radiation therapy for patients in whom metal objects have been implanted

  17. Value and clinical application of orthopedic metal artifact reduction algorithm in CT scans after orthopedic metal implantation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yi; Pan, Shinong; Zhao, Xudong; Guo, Wenli; He, Ming; Guo, Qiyong [Shengjing Hospital of China Medical University, Shenyang (China)

    2017-06-15

    To evaluate orthopedic metal artifact reduction algorithm (O-MAR) in CT orthopedic metal artifact reduction at different tube voltages, identify an appropriate low tube voltage for clinical practice, and investigate its clinical application. The institutional ethical committee approved all the animal procedures. A stainless-steel plate and four screws were implanted into the femurs of three Japanese white rabbits. Preoperative CT was performed at 120 kVp without O-MAR reconstruction, and postoperative CT was performed at 80–140 kVp with O-MAR. Muscular CT attenuation, artifact index (AI) and signal-to-noise ratio (SNR) were compared between preoperative and postoperative images (unpaired t test), between paired O-MAR and non-O-MAR images (paired Student t test) and among different kVp settings (repeated measures ANOVA). Artifacts' severity, muscular homogeneity, visibility of inter-muscular space and definition of bony structures were subjectively evaluated and compared (Wilcoxon rank-sum test). In the clinical study, 20 patients undertook CT scan at low kVp with O-MAR with informed consent. The diagnostic satisfaction of clinical images was subjectively assessed. Animal experiments showed that the use of O-MAR resulted in accurate CT attenuation, lower AI, better SNR, and higher subjective scores (p < 0.010) at all tube voltages. O-MAR images at 100 kVp had almost the same AI and SNR as non-O-MAR images at 140 kVp. All O-MAR images were scored ≥ 3. In addition, 95% of clinical CT images performed at 100 kVp were considered satisfactory. O-MAR can effectively reduce orthopedic metal artifacts at different tube voltages, and facilitates low-tube-voltage CT for patients with orthopedic metal implants.

  18. Value and clinical application of orthopedic metal artifact reduction algorithm in CT scans after orthopedic metal implantation

    International Nuclear Information System (INIS)

    Hu, Yi; Pan, Shinong; Zhao, Xudong; Guo, Wenli; He, Ming; Guo, Qiyong

    2017-01-01

    To evaluate orthopedic metal artifact reduction algorithm (O-MAR) in CT orthopedic metal artifact reduction at different tube voltages, identify an appropriate low tube voltage for clinical practice, and investigate its clinical application. The institutional ethical committee approved all the animal procedures. A stainless-steel plate and four screws were implanted into the femurs of three Japanese white rabbits. Preoperative CT was performed at 120 kVp without O-MAR reconstruction, and postoperative CT was performed at 80–140 kVp with O-MAR. Muscular CT attenuation, artifact index (AI) and signal-to-noise ratio (SNR) were compared between preoperative and postoperative images (unpaired t test), between paired O-MAR and non-O-MAR images (paired Student t test) and among different kVp settings (repeated measures ANOVA). Artifacts' severity, muscular homogeneity, visibility of inter-muscular space and definition of bony structures were subjectively evaluated and compared (Wilcoxon rank-sum test). In the clinical study, 20 patients undertook CT scan at low kVp with O-MAR with informed consent. The diagnostic satisfaction of clinical images was subjectively assessed. Animal experiments showed that the use of O-MAR resulted in accurate CT attenuation, lower AI, better SNR, and higher subjective scores (p < 0.010) at all tube voltages. O-MAR images at 100 kVp had almost the same AI and SNR as non-O-MAR images at 140 kVp. All O-MAR images were scored ≥ 3. In addition, 95% of clinical CT images performed at 100 kVp were considered satisfactory. O-MAR can effectively reduce orthopedic metal artifacts at different tube voltages, and facilitates low-tube-voltage CT for patients with orthopedic metal implants

  19. An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron–Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications

    Directory of Open Access Journals (Sweden)

    Yun Tu

    2017-02-01

    Full Text Available Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG fabricated in hydrogen (H2-loaded boron–germanium (B–Ge co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H2-loaded B–Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H2-loaded B–Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging.

  20. An environmentally-friendly vacuum reduction metallurgical process to recover germanium from coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingen; Xu, Zhenming, E-mail: zmxu@sjtu.edu.cn

    2016-07-15

    Highlights: • An environmental friendly vacuum reduction metallurgical process is proposed. • Rare and valuable metal germanium from coal fly ash is recycled. • Residues are not a hazardous material and can be further recycled. • A germanium recovery ratio of 94.64% is obtained in pilot scale experiments. - Abstract: The demand for germanium in the field of semiconductor, electronics, and optical devices is growing rapidly; however, the resources of germanium are scarce worldwide. As a secondary material, coal fly ash could be further recycled to retrieve germanium. Up to now, the conventional processes to recover germanium have two problems as follows: on the one hand, it is difficult to be satisfactory for its economic and environmental effect; on the other hand, the recovery ratio of germanium is not all that could be desired. In this paper, an environmentally-friendly vacuum reduction metallurgical process (VRMP) was proposed to recover germanium from coal fly ash. The results of the laboratory scale experiments indicated that the appropriate parameters were 1173 K and 10 Pa with 10 wt% coke addition for 40 min, and recovery ratio germanium was 93.96%. On the basis of above condition, the pilot scale experiments were utilized to assess the actual effect of VRMP for recovery of germanium with parameter of 1473 K, 1–10 Pa and heating time 40 min, the recovery ratio of germanium reached 94.64%. This process considerably enhances germanium recovery, meanwhile, eliminates much of the water usage and residue secondary pollution compared with other conventional processes.

  1. Percutaneous pulmonary valve implantation preceded by routine prestenting with a bare metal stent

    DEFF Research Database (Denmark)

    Demkow, Marcin; Biernacka, Elzbieta Katarzyna; Spiewak, Mateusz

    2011-01-01

    Objectives: To evaluate the effectiveness and safety of percutaneous pulmonary valve implantation (PPVI) with routine prestenting with a bare metal stent (BMS). Background: PPVI is a relatively new method of treating patients with repaired congenital heart disease (CHD). Results of PPVI performed.......6 ± 22.7 to 38.8 ± 10.4 mm Hg on the day following implantation (P = 0.001). At 1-month and 6-month follow-ups, mean RVOT gradient was 34.0 ± 9.8 and 32.0 ± 12.2 mm Hg, respectively. In patients with significant pulmonary regurgitation, mean pulmonary regurgitation fraction decreased from 19% ± 6% to 2...

  2. Immobilisation of krypton in a metallic matrix by combined ion implantation and sputtering

    International Nuclear Information System (INIS)

    Whitmell, D.S.

    1980-01-01

    With the increase in nuclear power, it may be necessary to contain for 100 to 200 years the radioactive 85 krypton released during fuel reprocessing. The ideal method of immobilising radioactive materials is in the form of stable, monolithic solids which are resistant to the effects of the environment or accidents, and which can retain the radioactivity under all envisaged conditions. Since krypton is a rare gas, not forming thermally stable compounds, conventional methods of storage are not possible. A process is being developed to immobilise the krypton in the form of small gas bubbles in a metal matrix by implanting the gas into a metal layer from a glow discharge and then burying the implanted layer by sputter deposition. By repeating the process, a thick layer of deposit is built up with the krypton dispersed throughout the matrix as bubbles of diameter less than 20 A. This process offers an ideal form of storage since gas in bubbles is not thermally released until the temperature of the matrix is close to the melting point, and also leakage of gas by corrosion or mechanical damage will be small. A pilot plant is being built in order to demonstrate the process on a scale comparable with that required for a reprocessing plant. The efficiency of the process is dependent upon the amount of gas which can be implanted at low energy into a thin layer and its subsequent retention. More information is required on the processes occurring when krypton ions are implanted close to the surface, in particular, the retention and re-emission of the gas, and the formation of clusters and bubbles. (author)

  3. N-Heterocyclic Carbene Coinage Metal Complexes of the Germanium-Rich Metalloid Clusters [Ge9R3]− and [Ge9RI2]2− with R = Si(iPr3 and RI = Si(TMS3

    Directory of Open Access Journals (Sweden)

    Felix S. Geitner

    2017-07-01

    Full Text Available We report on the synthesis of novel coinage metal NHC (N-heterocyclic carbene compounds of the germanium-rich metalloid clusters [Ge9R3]− and [Ge9RI2]2− with R = Si(iPr3 and RI = Si(TMS3. NHCDippCu{η3Ge9R3} with R = Si(iPr3 (1 represents a less bulky silyl group-substituted derivative of the known analogous compounds with R = Si(iBu3 or Si(TMS3. The coordination of the [NHCDippCu]+ moiety to the cluster unit occurs via one triangular face of the tri-capped trigonal prismatic [Ge9] cluster. Furthermore, a series of novel Zintl cluster coinage metal NHC compounds of the type (NHCM2{η3Ge9RI2} (RI = Si(TMS3 M = Cu, Ag and Au; NHC = NHCDipp or NHCMes is presented. These novel compounds represent a new class of neutral dinuclear Zintl cluster coinage metal NHC compounds, which are obtained either by the stepwise reaction of a suspension of K12Ge17 with Si(TMS3Cl and the coinage metal carbene complexes NHCMCl (M = Cu, Ag, Au, or via a homogenous reaction using the preformed bis-silylated cluster K2[Ge9(Si(TMS32] and the corresponding NHCMCl (M = Cu, Ag, Au complex. The molecular structures of NHCDippCu{η3Ge9(Si(iPr33} (1 and (NHCDippCu2{η3-Ge9(Si(TMS32} (2 were determined by single crystal X-ray diffraction methods. In 2, the coordination of the [NHCDippCu]+ moieties to the cluster unit takes place via both open triangular faces of the [Ge9] entity. Furthermore, all compounds were characterized by means of NMR spectroscopy (1H, 13C, 29Si and ESI-MS.

  4. Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm.

    Science.gov (United States)

    Sofue, Keitaro; Yoshikawa, Takeshi; Ohno, Yoshiharu; Negi, Noriyuki; Inokawa, Hiroyasu; Sugihara, Naoki; Sugimura, Kazuro

    2017-07-01

    To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P small metal implants by reducing metallic artefacts. • SEMAR algorithm significantly reduces metallic artefacts from small implants in abdominal CT. • SEMAR can improve image quality of the liver in dynamic CECT. • Confidence visualization of hepatic vascular anatomies can also be improved by SEMAR.

  5. Tunable conductivity in mesoporous germanium

    Science.gov (United States)

    Beattie, Meghan N.; Bioud, Youcef A.; Hobson, David G.; Boucherif, Abderraouf; Valdivia, Christopher E.; Drouin, Dominique; Arès, Richard; Hinzer, Karin

    2018-05-01

    Germanium-based nanostructures have attracted increasing attention due to favourable electrical and optical properties, which are tunable on the nanoscale. High densities of germanium nanocrystals are synthesized via electrochemical etching, making porous germanium an appealing nanostructured material for a variety of applications. In this work, we have demonstrated highly tunable electrical conductivity in mesoporous germanium layers by conducting a systematic study varying crystallite size using thermal annealing, with experimental conductivities ranging from 0.6 to 33 (×10‑3) Ω‑1 cm‑1. The conductivity of as-prepared mesoporous germanium with 70% porosity and crystallite size between 4 and 10 nm is shown to be ∼0.9 × 10‑3 Ω‑1 cm‑1, 5 orders of magnitude smaller than that of bulk p-type germanium. Thermal annealing for 10 min at 400 °C further reduced the conductivity; however, annealing at 450 °C caused a morphological transformation from columnar crystallites to interconnecting granular crystallites and an increase in conductivity by two orders of magnitude relative to as-prepared mesoporous germanium caused by reduced influence of surface states. We developed an electrostatic model relating the carrier concentration and mobility of p-type mesoporous germanium to the nanoscale morphology. Correlation within an order of magnitude was found between modelled and experimental conductivities, limited by variation in sample uniformity and uncertainty in void size and fraction after annealing. Furthermore, theoretical results suggest that mesoporous germanium conductivity could be tuned over four orders of magnitude, leading to optimized hybrid devices.

  6. Electroconvulsive therapy in patients with skull defects or metallic implants: a review of the literature and case report.

    Science.gov (United States)

    Amanullah, Shabbir; Delva, Nicholas; McRae, Harold; Campbell, Laura A; Cole, Julie

    2012-01-01

    Head injury is often associated with psychiatric morbidity. While it is well understood that the loss of critical areas of the brain may play a role in cognitive dysfunction and change in personality, head injury can also have profound effects on mood and cognition. The role of medications in the treatment of mood disorders associated with brain injury is well documented, and there is also evidence favoring the use of electroconvulsive therapy (ECT) in this context. However, data are limited on the use of ECT in patients with skull defects or metallic head implants. First, a review of the literature on use of ECT in patients with metallic head implants is provided. Electronic databases and online sites, including PubMed, Cochrane Library of Systematic Reviews, and UpToDate, were used to search for relevant articles and case reports on the use of ECT in patients with and without metallic implants in the head (1964 to 2009). The search terms electroconvulsive, electroconvulsive therapy, ECT, electroshock therapy, EST, head injury, brain injury, metallic plates, metallic implants, skull prosthesis, and depression were used interchangeably. The search produced 7 articles discussing exclusively the use of ECT in patients with a metallic skull plate. Second, the case of the successful and safe use of ECT in an individual with a previous history of brain trauma and metallic plate implantation is described. Most cases of head injury are managed by neurologists and rehabilitation consultants; the more severe cases of depression and other mood disorders tend to be referred for specialist psychiatric care. With greater degrees of deficit following head injury, management becomes more complicated. Our patient showed positive results with ECT, including improvement in depressive features and resolution of suicidal ideas/plans. ECT is an effective and safe alternative in patients with a history of brain trauma and metallic plate implantation who subsequently develop treatment

  7. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants

    International Nuclear Information System (INIS)

    Ahlawat, Shivani; Fritz, Jan; Stern, Steven E.; Belzberg, Allan J.

    2017-01-01

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips. (orig.)

  8. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Ahlawat, Shivani; Fritz, Jan [The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Stern, Steven E. [Bond University, Bond Business School, Gold Coast, QLD (Australia); Belzberg, Allan J. [Johns Hopkins University School of Medicine, Department of Neurosurgery, Baltimore, MD (United States)

    2017-07-15

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips. (orig.)

  9. Demonstration of metallic implants by means of digital luminescence radiography (DLR)

    International Nuclear Information System (INIS)

    Wiesmann, W.; Reiser, M.; Fiebich, M.; Bick, U.; Peters, P.E.

    1990-01-01

    DLR makes it possible to integrate conventional radiography into digital communication and storage methods (PACS) into radiology. The use of DLR has been compared with conventional film methods in the demonstration of hip prostheses. The high contrast differences at the edge of the metal implant leads to artifacts, which could result in erroneous interpretation. Suitable image manipulation makes it possible, however, to eliminate these artifacts almost completely. DLR leads to an improvement in diagnosis in those complications not specifically related to the prostheses. (orig.) [de

  10. A high current metal vapour vacuum arc ion source for ion implantation studies

    International Nuclear Information System (INIS)

    Evans, P.J.; Noorman, J.T.; Watt, G.C.; Cohen, D.D.; Bailey, G.M.

    1989-01-01

    The main features of the metal vapour vacuum arc(MEVA) as an ion source are presented. The technology utilizes the plasma production capabilities of a vacuum arc cathode. Some of the ions produced in this discharge flow through the anode and the 3 extraction grids to form an extracted ion beam. The high beam current and the potential for generating broad beams, make this technology suitable for implantation of large surface areas. The composition of the vacuum arc cathode determines the particular ions obtained from the MEVA source. 3 refs., 1 tab., 2 figs

  11. Plasma source ion implantation of metal ions: Synchronization of cathodic-arc plasma production and target bias pulses

    International Nuclear Information System (INIS)

    Wood, B.P.; Reass, W.A.; Henins, I.

    1995-01-01

    An erbium cathodic-arc has been installed on a Plasma Source Ion Implantation (PSII) experiment to allow the implantation of erbium metal and the growth of adherent erbia (erbium oxide) films on a variety of substrates. Operation of the PSII pulser and the cathodic-arc are synchronized to achieve pure implantation, rather than the hybrid implantation/deposition being investigated in other laboratories. The relative phase of the 20 μs PSII and cathodic-arc pulses can to adjusted to tailor the energy distribution of implanted ions and suppress the initial high-current drain on the pulse modulator. The authors present experimental data on this effect and make a comparison to results from particle-in-cell simulations

  12. Moessbauer spectroscopy of isotope separator implanted sup(119m)Sn in FCC metals

    International Nuclear Information System (INIS)

    Larsen, A.N.; Weyer, G.

    1979-01-01

    Radioactive sup(119m)Sn has been implanted in FCC metals by means of an isotope separator. Moessbauer spectra have been measured for the 24 keV transition of 119 Sn. Large substitutional fractions are found in all cases. A correlation for substitutional lattice sites between the measured isomer shifts of the impurity atoms and the force constants of the host lattices is discussed. Debye-Waller factors determined for substitutional Sn in the host lattices are found to be smaller than values calculated by a simple mass-defect model. For some host metals indications of an influence of radiation damage on the spectra are observed. Defect sites are assigned to Sn in aluminium and lead. Qualitative conclusions on the structures of these defects are drawn from the determined Moessbauer parameters. (author)

  13. Engineering of bone fixation metal implants biointerface-Application of parylene C as versatile protective coating

    Energy Technology Data Exchange (ETDEWEB)

    Cieslik, Monika, E-mail: cieslik@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Institute of Metallurgy and Materials Science, PAS, W. Reymonta 25, 30-059 Krakow (Poland); Zimowski, Slawomir [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Golda, Monika [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Institute of Metallurgy and Materials Science, PAS, W. Reymonta 25, 30-059 Krakow (Poland); Engvall, Klas [KTH Royal Institute of Technology, Department of Chemical Engineering and Technology, Division of Chemical Technology, Drottning Kristinas vaeg. 42, SE-100 44 Stockholm (Sweden); Pan, Jinshan [KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas vaeg. 51, SE-100 44 Stockholm (Sweden); Rakowski, Wieslaw [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Kotarba, Andrzej, E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2012-12-01

    The tribological and protective properties of parylene C coatings (2-20 {mu}m) on stainless steel 316L implant materials were investigated by means of electrochemical measurements and wear tests. The thickness and morphology of the CVD prepared coatings were characterized by scanning electron and laser confocal microscopy. The stability of the coatings was examined in contact with Hanks' solution and H{sub 2}O{sub 2} (simulating the inflammatory response). It was concluded that silane-parylene C coating with the optimum thickness of 8 {mu}m exhibits excellent wear resistance properties and limits the wear formation. The engineered versatile coating demonstrates sufficient elastomer properties, essential to sustain the implantation surgery strains and micromotions during long-term usage in the body. - Highlights: Black-Right-Pointing-Pointer A versatile coating for protection of metal implant surface is proposed. Black-Right-Pointing-Pointer The protective properties of 2-20 {mu}m silane-parylene C coating were examined. Black-Right-Pointing-Pointer The engineered material proves its high anticorrosive and wear resistance. Black-Right-Pointing-Pointer The practical implications of the coating properties were discussed.

  14. Metallization of ion beam synthesized Si/3C-SiC/Si layer systems by high-dose implantation of transition metal ions

    International Nuclear Information System (INIS)

    Lindner, J.K.N.; Wenzel, S.; Stritzker, B.

    2001-01-01

    The formation of metal silicide layers contacting an ion beam synthesized buried 3C-SiC layer in silicon by means of high-dose titanium and molybdenum implantations is reported. Two different strategies to form such contact layers are explored. The titanium implantation aims to convert the Si top layer of an epitaxial Si/SiC/Si layer sequence into TiSi 2 , while Mo implantations were performed directly into the SiC layer after selectively etching off all capping layers. Textured and high-temperature stable C54-TiSi 2 layers with small additions of more metal-rich silicides are obtained in the case of the Ti implantations. Mo implantations result in the formation of the high-temperature phase β-MoSi 2 , which also grows textured on the substrate. The formation of cavities in the silicon substrate at the lower SiC/Si interface due to the Si consumption by the growing silicide phase is observed in both cases. It probably constitutes a problem, occurring whenever thin SiC films on silicon have to be contacted by silicide forming metals independent of the deposition technique used. It is shown that this problem can be solved with ion beam synthesized contact layers by proper adjustment of the metal ion dose

  15. A study of enhanced diffusion during high dose high flux pulsed metal ion implantation into steel and aluminium

    International Nuclear Information System (INIS)

    Zhang Tonghe; Ji Chengzhou; Shen Jinghua; Chen Jun

    1992-01-01

    The depth profiles of metal ions implanted into steel and aluminium were measured by Rutherford backscattering (RBS). The ions of Mo, W and Y, produced by a metal vapour vacuum are ion source (MEVVA) were implanted at an energy range from 25 to 50 keV for doses of (2-5)x10 17 cm -2 into H13 steel and aluminium. Beam currents were from 0.5 to 1.0 A. The beam flux is in the range of 25 to 75 μAcm -2 . In order to simulate the profiles, a formula which includes the sputtering yield, diffusion coefficients and reaction rate was obtained. The results demonstrate that the penetration depth and retained dose increase with increasing beam flux for Mo implanted into aluminium. The peak concentration of Mo implanted H13 steel increases with increasing ion flux. In contrast to this for Y implantation into steel, the peak concentration of Y decreases with increasing ion flux. For an ion flux of 25 μAcm -2 for Mo, Y and W implantation into steel, the penetration depth and retained dose are 3-5 times greater than the theoretical values. The diffusion coefficients are about 10 -16 to 10 -15 s -1 . If the ion flux is greater than 47 μAcm -2 , the penetration depth and retained dose are 5 to 10 times greater than the theoretical values for Mo implanted aluminium. The diffusion coefficients increase with increasing ion flux for Mo implanted aluminium. The diffusion coefficients hardly change with increasing ion flux for Y and Mo implanted H13 steel. The retained dose increases 0.43 to 1.16 times for Y implanted steel for an ion flux of 25 μAcm -2 . Finally, the influence of phases precipitates, reaction rate and diffusion on retained dose, diffusion coefficient and penetration depth are discussed. (orig.)

  16. The Effect of Susceptibility Artifacts Related to Metallic Implants on Adjacent-Lesion Assessment in Simultaneous TOF PET/MR.

    Science.gov (United States)

    Svirydenka, Hanna; Delso, Gaspar; De Galiza Barbosa, Felipe; Huellner, Martin; Davison, Helen; Fanti, Stefano; Veit-Haibach, Patrick; Ter Voert, Edwin E G W

    2017-07-01

    Metalic implants may affect attenuation correction (AC) in PET/MR imaging. The purpose of this study was to evaluate the effect of susceptibility artifacts related to metallic implants on adjacent metabolically active lesions in clinical simultaneous PET/MR scanning for both time-of-flight (TOF) and non-TOF reconstructed PET images. Methods: We included 27 patients without implants but with confirmed 18 F-FDG-avid lesions adjacent to common implant locations. In all patients, a clinically indicated whole-body 18 F-FDG PET/MR scan was acquired. Baseline non-TOF and TOF PET images were reconstructed. Reconstruction was repeated after the introduction of artificial signal voids in the AC map to simulate metallic implants in standard anatomic areas. All reconstructed images were qualitatively and quantitatively assessed and compared with the baseline images. Results: In total, 51 lesions were assessed. In 40 and 50 of these cases (non-TOF and TOF, respectively), the detectability of the lesions did not change; in 9 and 1 cases, the detectability changed; and in 2 non-TOF cases, the lesions were no longer visible after the introduction of metallic artifacts. The inclusion of TOF information significantly reduced artifacts due to simulated implants in the femoral head, sternum, and spine ( P = 0.01, 0.01, and 0.03, respectively). It also improved image quality in these locations ( P = 0.02, 0.01, and 0.01, respectively). The mean percentage error was -3.5% for TOF and -4.8% for non-TOF reconstructions, meaning that the inclusion of TOF information reduced the percentage error in SUV max by 28.5% ( P metallic implants have a significant effect on small, moderately 18 F-FDG-avid lesions near the implant site that possibly may go unnoticed without TOF information. On larger, highly 18 F-FDG-avid lesions, the metallic implants had only a limited effect. The largest significant quantitative difference was found in artifacts of the sternum. There was only a weak inverse

  17. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

    Science.gov (United States)

    Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

  18. Assessment of the genetic risks of a metallic alloy used in medical implants.

    Science.gov (United States)

    Gomes, Cristiano C; Moreira, Leonardo M; Santos, Vanessa J S V; Ramos, Alfeu S; Lyon, Juliana P; Soares, Cristina P; Santos, Fabio V

    2011-01-01

    The use of artificial implants provides a palliative or permanent solution for individuals who have lost some bodily function through disease, an accident or natural wear. This functional loss can be compensated for by the use of medical devices produced from special biomaterials. Titanium alloy (Ti-6Al-4V) is a well-established primary metallic biomaterial for orthopedic implants, but the toxicity of the chemical components of this alloy has become an issue of concern. In this work, we used the MTT assay and micronucleus assay to examine the cytotoxicity and genotoxicity, respectively, of an extract obtained from this alloy. The MTT assay indicated that the mitochondrial activity and cell viability of CHO-K1 cells were unaffected by exposure to the extract. However, the micronucleus assay revealed DNA damage and an increase in micronucleus frequency at all of the concentrations tested. These results show that ions released from Ti-6Al-4V alloy can cause DNA and nuclear damage and reinforce the importance of assessing the safety of metallic medical devices constructed from biomaterials.

  19. Hearing loss and potential hazards of metallic middle-ear implants in NMR-magnetic fields

    International Nuclear Information System (INIS)

    Huettenbrink, K.B.

    1987-01-01

    Concurrent with the expanding clinical applications of nuclear magnetic resonance (NMR) imaging, patients with metallic middle-ear implants will certainly be exposed to this strong magnetic field in the future. To determine potential hazards, associated with movements of steel- or Platinium stapes-prostheses, several tests were performed in a 0.5 tesla NMR unit and the induced forces were calculated. Although the commonly used paramagnetic steel-wire or platinium-alloys will not dislodge in vivo, ferromagnetic prostheses may present a hazardous risk. Prior to exposure to the magnetic field, information about the implanted material should therefore be obtained. A side-effect of the induced current flow is the attenuation of the sound-vibrations of the stapes prosthesis. This, 5-10 dB impairment of transmission develops only at a certain position of the patient's head, when the prosthesis vibrates perpendicularly to the magnetic field's Z-axis. Patients with a metallic prosthesis should be informed about this purely physical, harmless phenomenon prior to entering the NMR-cylinder. (orig.) [de

  20. Brief ultrasonication improves detection of biofilm-formative bacteria around a metal implant.

    Science.gov (United States)

    Kobayashi, Naomi; Bauer, Thomas W; Tuohy, Marion J; Fujishiro, Takaaki; Procop, Gary W

    2007-04-01

    Biofilms are complex microenvironments produced by microorganisms on surfaces. Ultrasonication disrupts biofilms and may make the microorganism or its DNA available for detection. We determined whether ultrasonication could affect our ability to detect bacteria adherent to a metal substrate. A biofilm-formative Staphylococcus aureus strain was used for an in vitro implant infection model (biofilm-formative condition). We used quantitative culture and real time-polymerase chain reaction to determine the influence of different durations of ultrasound on bacterial adherence and viability. Sonication for 1 minute increased the yield of bacteria. Sonication longer than 5 minutes led to fewer bacterial colonies by conventional culture but not by polymerase chain reaction. This suggests short periods of sonication help release bacteria from the metal substrate by disrupting the biofilm, but longer periods of sonication lyse bacteria prohibiting their detection in microbiologic cultures. A relatively short duration of sonication may be desirable for maximizing detection of biofilm-formative bacteria around implants by culture or polymerase chain reaction.

  1. Ultrafast optical phase modulation with metallic nanoparticles in ion-implanted bilayer silica

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Torres, C [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, Mexico, DF, 07738 (Mexico); Tamayo-Rivera, L; Silva-Pereyra, H G; Reyes-Esqueda, J A; Rodriguez-Fernandez, L; Crespo-Sosa, A; Cheang-Wong, J C; Oliver, A [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 04510, Mexico, DF (Mexico); Rangel-Rojo, R [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada Apartado Postal 360, Ensenada, BC, 22860 (Mexico); Torres-Martinez, R, E-mail: crstorres@yahoo.com.mx [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada Unidad Queretaro, Instituto Politecnico Nacional, Santiago de Queretaro, Queretaro, 76090 (Mexico)

    2011-09-02

    The nonlinear optical response of metallic-nanoparticle-containing composites was studied with picosecond and femtosecond pulses. Two different types of nanocomposites were prepared by an ion-implantation process, one containing Au nanoparticles (NPs) and the other Ag NPs. In order to measure the optical nonlinearities, we used a picosecond self-diffraction experiment and the femtosecond time-resolved optical Kerr gate technique. In both cases, electronic polarization and saturated absorption were identified as the physical mechanisms responsible for the picosecond third-order nonlinear response for a near-resonant 532 nm excitation. In contrast, a purely electronic nonlinearity was detected at 830 nm with non-resonant 80 fs pulses. Regarding the nonlinear optical refractive behavior, the Au nanocomposite presented a self-defocusing effect, while the Ag one presented the opposite, that is, a self-focusing response. But, when evaluating the simultaneous contributions when the samples are tested as a multilayer sample (silica-Au NPs-silica-Ag NPs-silica), we were able to obtain optical phase modulation of ultra-short laser pulses, as a result of a significant optical Kerr effect present in these nanocomposites. This allowed us to implement an ultrafast all-optical phase modulator device by using a combination of two different metallic ion-implanted silica samples. This control of the optical phase is a consequence of the separate excitation of the nonlinear refracting phenomena exhibited by the separate Au and Ag nanocomposites.

  2. Theoretical examination of the trapping of ion-implanted hydrogen in metals

    International Nuclear Information System (INIS)

    Myers, S.M.; Nordlander, P.; Besenbacher, F.; Norskov, J.K.

    1986-01-01

    Theoretical analysis of the defect trapping of ion-implanted hydrogen in metals has been extended in two respects. A new transport formalism has been developed which takes account not only of the diffusion, trapping, and surface release of the hydrogen, which were included in earlier treatments, but also the diffusion, recombination, agglomeration, and surface annihilation of the vacancy and interstitial traps. In addition, effective-medium theory has been used to examine multiple hydrogen occupancy of the vacancy, and, for the fcc structure, appreciable binding enthalpies relative to the solution site have been found for occupancies of up to six. These extensions have been employed to model the depth distribution of ion-implanted hydrogen in Ni and Al during linear ramping of temperature, and the results have been used to interpret previously published data from these metals. The agreement between theory and experiment is good for both systems. In the case of Ni, the two experimentally observed hydrogen-release stages are both accounted for in terms of trapping at vacancies with a binding enthalpy that depends upon occupancy in accord with effective-medium theory

  3. Ultrafast optical phase modulation with metallic nanoparticles in ion-implanted bilayer silica

    International Nuclear Information System (INIS)

    Torres-Torres, C; Tamayo-Rivera, L; Silva-Pereyra, H G; Reyes-Esqueda, J A; Rodriguez-Fernandez, L; Crespo-Sosa, A; Cheang-Wong, J C; Oliver, A; Rangel-Rojo, R; Torres-Martinez, R

    2011-01-01

    The nonlinear optical response of metallic-nanoparticle-containing composites was studied with picosecond and femtosecond pulses. Two different types of nanocomposites were prepared by an ion-implantation process, one containing Au nanoparticles (NPs) and the other Ag NPs. In order to measure the optical nonlinearities, we used a picosecond self-diffraction experiment and the femtosecond time-resolved optical Kerr gate technique. In both cases, electronic polarization and saturated absorption were identified as the physical mechanisms responsible for the picosecond third-order nonlinear response for a near-resonant 532 nm excitation. In contrast, a purely electronic nonlinearity was detected at 830 nm with non-resonant 80 fs pulses. Regarding the nonlinear optical refractive behavior, the Au nanocomposite presented a self-defocusing effect, while the Ag one presented the opposite, that is, a self-focusing response. But, when evaluating the simultaneous contributions when the samples are tested as a multilayer sample (silica-Au NPs-silica-Ag NPs-silica), we were able to obtain optical phase modulation of ultra-short laser pulses, as a result of a significant optical Kerr effect present in these nanocomposites. This allowed us to implement an ultrafast all-optical phase modulator device by using a combination of two different metallic ion-implanted silica samples. This control of the optical phase is a consequence of the separate excitation of the nonlinear refracting phenomena exhibited by the separate Au and Ag nanocomposites.

  4. Mandibular remodeling measured on cephalograms. 1. Osseous changes relative to superimposition on metallic implants.

    Science.gov (United States)

    Baumrind, S; Ben-Bassat, Y; Korn, E L; Bravo, L A; Curry, S

    1992-08-01

    We report the results of a study aimed at quantifying remodeling of mandibular surfaces in a sample of growing children who represent those usually treated by orthodontists in the mixed and early adult dentition. The sample, 31 patients with metallic implants of the Björk-type, was monitored at annual intervals between 8 1/2 and 15 1/2 years of age. (Maxillary remodeling changes for the sample have been reported earlier.) The present article reports findings concerning changes at condyle, gonion, menton, pogonion, and point B as identified on lateral cephalograms. Data are reported in the Frankfort plane frame of reference with the cephalograms from different time points superimposed on the metallic implants. Mean displacement at condyle was larger than that at any other landmark and was similar in magnitude and direction to the observations of Björk when the difference in orientation of the vertical axis in the two studies is taken into account. The mean displacement of gonion was in an upward and backward direction at an angle of approximately 45 degrees to the Frankfort plane. Mean displacements at menton and pogonion were in a downward and backward direction but were very small. Mean displacement at point B was somewhat greater than that of menton and gonion, oriented in an upward and backward direction. Individual variation for most of the parameters measured was sufficiently large to warrant the inference that caution should be used when mean values are applied to the analysis of individual cases.

  5. The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage.

    Science.gov (United States)

    Neal, Robert E; Smith, Ryan L; Kavnoudias, Helen; Rosenfeldt, Franklin; Ou, Ruchong; Mclean, Catriona A; Davalos, Rafael V; Thomson, Kenneth R

    2013-12-01

    Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

  6. Characterization of wear debris from metal-on-metal hip implants during normal wear versus edge-loading conditions.

    Science.gov (United States)

    Kovochich, Michael; Fung, Ernest S; Donovan, Ellen; Unice, Kenneth M; Paustenbach, Dennis J; Finley, Brent L

    2018-04-01

    Advantages of second-generation metal-on-metal (MoM) hip implants include low volumetric wear rates and the release of nanosized wear particles that are chemically inert and readily cleared from local tissue. In some patients, edge loading conditions occur, which result in higher volumetric wear. The objective of this study was to characterize the size, morphology, and chemistry of wear particles released from MoM hip implants during normal (40° angle) and edge-loading (65° angle with microseparation) conditions. The mean primary particle size by volume under normal wear was 35 nm (range: 9-152 nm) compared with 95 nm (range: 6-573 nm) under edge-loading conditions. Hydrodynamic diameter analysis by volume showed that particles from normal wear were in the nano- (edge-loading conditions generated particles that ranged from Edge-loading conditions generated more elongated particles (4.5%) (aspect ratio ≥ 2.5) and more CoCr alloy particles (9.3%) compared with normal wear conditions (1.3% CoCr particles). By total mass, edge-loading particles contained approximately 640-fold more cobalt than normal wear particles. Our findings suggest that high wear conditions are a potential risk factor for adverse local tissue effects in MoM patients who experience edge loading. This study is the first to characterize both the physical and chemical characteristics of MoM wear particles collected under normal and edge-loading conditions. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 986-996, 2018. © 2017 Wiley Periodicals, Inc.

  7. Metallic stent implantation combined with intra-arterial chemotherapy for the treatment of malignant gastric and duodenal obstruction

    International Nuclear Information System (INIS)

    Cao Jun; Liu Hongqiang; He Yang; Xia Ning; Zhang Honglei; Qiao Delin

    2011-01-01

    Objective: To investigate the clinical effect of metallic stent implantation together with intra-arterial chemotherapy in treating malignant gastric and duodenal obstruction. Methods: A total of 32 patients with malignant gastric and duodenal obstruction were enrolled in this study. The obstructed sites were located at the gastric sinus and pylorus part (n=16), at the gastroduodenal anastomotic stoma (n=6) or at the descending part of duodenum (n=10). Under DSA guidance and with the additional help of endoscopy, a guide-wire was orally placed in the gastroduodenal obstructed site, which was followed by the implantation of the self-expanding metallic stent (Ni-Ti alloy). Postoperative intra-arterial chemotherapy via the tumor-feeding arteries was carried out in 16 patients (dual interventional therapy). The clinical results were analyzed. Results: Successful stent insertion was achieved in all 32 patients (100%). After stent implantation the obstructive symptoms were markedly relieved and the food intake was improved. No serious complications occurred. The median survival time for the 16 patients who had received dual interventional therapy was 9.3 months, while the median survival time for the other 16 patients who had received simple stenting therapy was 5.7 months. Conclusion: For the treatment of inoperable malignant gastroduodenal obstruction, the implantation of metallic self-expanding stents is a technically simple, clinically safe and effective palliative measure. Combined with postoperative intra-arterial chemotherapy, the metal stent implantation can control the tumor growth and elongate the survival time. (authors)

  8. Iterative metal artifact reduction improves dose calculation accuracy. Phantom study with dental implants

    Energy Technology Data Exchange (ETDEWEB)

    Maerz, Manuel; Mittermair, Pia; Koelbl, Oliver; Dobler, Barbara [Regensburg University Medical Center, Department of Radiotherapy, Regensburg (Germany); Krauss, Andreas [Siemens Healthcare GmbH, Forchheim (Germany)

    2016-06-15

    Metallic dental implants cause severe streaking artifacts in computed tomography (CT) data, which affect the accuracy of dose calculations in radiation therapy. The aim of this study was to investigate the benefit of the metal artifact reduction algorithm iterative metal artifact reduction (iMAR) in terms of correct representation of Hounsfield units (HU) and dose calculation accuracy. Heterogeneous phantoms consisting of different types of tissue equivalent material surrounding metallic dental implants were designed. Artifact-containing CT data of the phantoms were corrected using iMAR. Corrected and uncorrected CT data were compared to synthetic CT data to evaluate accuracy of HU reproduction. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated in Oncentra v4.3 on corrected and uncorrected CT data and compared to Gafchromic trademark EBT3 films to assess accuracy of dose calculation. The use of iMAR increased the accuracy of HU reproduction. The average deviation of HU decreased from 1006 HU to 408 HU in areas including metal and from 283 HU to 33 HU in tissue areas excluding metal. Dose calculation accuracy could be significantly improved for all phantoms and plans: The mean passing rate for gamma evaluation with 3 % dose tolerance and 3 mm distance to agreement increased from 90.6 % to 96.2 % if artifacts were corrected by iMAR. The application of iMAR allows metal artifacts to be removed to a great extent which leads to a significant increase in dose calculation accuracy. (orig.) [German] Metallische Implantate verursachen streifenfoermige Artefakte in CT-Bildern, welche die Dosisberechnung beeinflussen. In dieser Studie soll der Nutzen des iterativen Metall-Artefakt-Reduktions-Algorithmus iMAR hinsichtlich der Wiedergabetreue von Hounsfield-Werten (HU) und der Genauigkeit von Dosisberechnungen untersucht werden. Es wurden heterogene Phantome aus verschiedenen Arten gewebeaequivalenten Materials mit

  9. N-Acetyl-Cysteine as Effective and Safe Chelating Agent in Metal-on-Metal Hip-Implanted Patients: Two Cases

    Directory of Open Access Journals (Sweden)

    Andrea Giampreti

    2016-01-01

    Full Text Available Systemic toxicity associated with cobalt (Co and chromium (Cr containing metal hip alloy may result in neuropathy, cardiomyopathy, and hypothyroidism. However clinical management concerning chelating therapy is still debated in literature. Here are described two metal-on-metal hip-implanted patients in which N-acetyl-cysteine decreased elevated blood metal levels. A 67-year-old male who underwent Co/Cr hip implant in September 2009 referred to our Poison Control Centre for persisting elevated Co/Cr blood levels (from March 2012 to November 2014. After receiving oral high-dose N-acetyl-cysteine, Co/Cr blood concentrations dropped by 86% and 87% of the prechelation levels, respectively, and persisted at these latter concentrations during the following 6 months of follow-up. An 81-year-old female who underwent Co/Cr hip implant in January 2007 referred to our Centre for detection of high Co and Cr blood levels in June 2012. No hip revision was indicated. After a therapy with oral high-dose N-acetyl-cysteine Co/Cr blood concentrations decreased of 45% and 24% of the prechelation levels. Chelating agents reported in hip-implanted patients (EDTA, DMPS, and BAL are described in few cases. N-acetyl-cysteine may provide chelating sites for metals and in our cases reduced Co and Cr blood levels and resulted well tolerable.

  10. Metal Artifact Reduction in X-ray Computed Tomography Using Computer-Aided Design Data of Implants as Prior Information.

    Science.gov (United States)

    Ruth, Veikko; Kolditz, Daniel; Steiding, Christian; Kalender, Willi A

    2017-06-01

    The performance of metal artifact reduction (MAR) methods in x-ray computed tomography (CT) suffers from incorrect identification of metallic implants in the artifact-affected volumetric images. The aim of this study was to investigate potential improvements of state-of-the-art MAR methods by using prior information on geometry and material of the implant. The influence of a novel prior knowledge-based segmentation (PS) compared with threshold-based segmentation (TS) on 2 MAR methods (linear interpolation [LI] and normalized-MAR [NORMAR]) was investigated. The segmentation is the initial step of both MAR methods. Prior knowledge-based segmentation uses 3-dimensional registered computer-aided design (CAD) data as prior knowledge to estimate the correct position and orientation of the metallic objects. Threshold-based segmentation uses an adaptive threshold to identify metal. Subsequently, for LI and NORMAR, the selected voxels are projected into the raw data domain to mark metal areas. Attenuation values in these areas are replaced by different interpolation schemes followed by a second reconstruction. Finally, the previously selected metal voxels are replaced by the metal voxels determined by PS or TS in the initial reconstruction. First, we investigated in an elaborate phantom study if the knowledge of the exact implant shape extracted from the CAD data provided by the manufacturer of the implant can improve the MAR result. Second, the leg of a human cadaver was scanned using a clinical CT system before and after the implantation of an artificial knee joint. The results were compared regarding segmentation accuracy, CT number accuracy, and the restoration of distorted structures. The use of PS improved the efficacy of LI and NORMAR compared with TS. Artifacts caused by insufficient segmentation were reduced, and additional information was made available within the projection data. The estimation of the implant shape was more exact and not dependent on a threshold

  11. Characterization of the bone-metal implant interface by Digital Volume Correlation of in-situ loading using neutron tomography.

    Science.gov (United States)

    Le Cann, Sophie; Tudisco, Erika; Perdikouri, Christina; Belfrage, Ola; Kaestner, Anders; Hall, Stephen; Tägil, Magnus; Isaksson, Hanna

    2017-11-01

    Metallic implants are commonly used as surgical treatments for many orthopedic conditions. The long-term stability of implants relies on an adequate integration with the surrounding bone. Unsuccessful integration could lead to implant loosening. By combining mechanical loading with high-resolution 3D imaging methods, followed by image analysis such as Digital Volume Correlation (DVC), we aim at evaluating ex vivo the mechanical resistance of newly formed bone at the interface. X-rays tomography is commonly used to image bone but induces artefacts close to metallic components. Utilizing a different interaction with matter, neutron tomography is a promising alternative but has not yet been used in studies of bone mechanics. This work demonstrates that neutron tomography during in situ loading is a feasible tool to characterize the mechanical response of bone-implant interfaces, especially when combined with DVC. Experiments were performed where metal screws were implanted in rat tibiae during 4 weeks. The screws were pulled-out while the samples were sequentially imaged in situ with neutron tomography. The images were analyzed to quantify bone ingrowth around the implants. DVC was used to track the internal displacements and calculate the strain fields in the bone during loading. The neutron images were free of metal-related artefacts, which enabled accurate quantification of bone ingrowth on the screw (ranging from 60% to 71%). DVC allowed successful identification of the deformation and cracks that occurred during mechanical loading and led to final failure of the bone-implant interface. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Porous germanium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garralaga Rojas, Enrique; Hensen, Jan; Brendel, Rolf [Institut fuer Solarenergieforschung Hameln (ISFH), Emmerthal (Germany); Carstensen, Juergen; Foell, Helmut [Chair for General Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany)

    2011-06-15

    We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4'' p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Activation of human leukocytes on tantalum trabecular metal in comparison to commonly used orthopedic metal implant materials.

    Science.gov (United States)

    Schildhauer, T A; Peter, E; Muhr, G; Köller, M

    2009-02-01

    We analyzed leukocyte functions and cytokine response of human leukocytes toward porous tantalum foam biomaterial (Trabecular Metaltrade mark, TM) in comparison to equally sized solid orthopedic metal implant materials (pure titanium, titanium alloy, stainless steel, pure tantalum, and tantalum coated stainless steel). Isolated peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) were cocultured with equally sized metallic test discs for 24 h. Supernatants were analyzed for cytokine content by enzyme-linked immunosorbent assay. Compared to the other used test materials there was a significant increase in the release of IL (interleukin)-1ra and IL-8 from PMN, and of IL-1ra, IL-6, and TNF-alpha from PBMC in response to the TM material. The cytokine release correlated with surface roughness of the materials. In contrast, the release of IL-2 was not induced showing that mainly myeloid leukocytes were activated. In addition, supernatants of these leukocyte/material interaction (conditioned media, CM) were subjected to whole blood cell function assays (phagocytosis, chemotaxis, bacterial killing). There was a significant increase in the phagocytotic capacity of leukocytes in the presence of TM-conditioned media. The chemotactic response of leukocytes toward TM-conditioned media was significantly higher compared to CM obtained from other test materials. Furthermore, the bactericidal capacity of whole blood was enhanced in the presence of TM-conditioned media. These results indicate that leukocyte activation at the surface of TM material induces a microenvironment, which may enhance local host defense mechanisms.

  14. Dose perturbation effect of metallic spinal implants in proton beam therapy.

    Science.gov (United States)

    Jia, Yingcui; Zhao, Li; Cheng, Chee-Wai; McDonald, Mark W; Das, Indra J

    2015-09-08

    The purpose of this study was to investigate the effect of dose perturbations for two metallic spinal screw implants in proton beam therapy in the perpendicular and parallel beam geometry. A 5.5 mm (diameter) by 45 mm (length) stainless steel (SS) screw and a 5.5 mm by 35 mm titanium (Ti) screw commonly used for spinal fixation were CT-scanned in a hybrid phantom of water and solid water. The CT data were processed with an orthopedic metal artifact reduction (O-MAR) algorithm. Treatment plans were generated for each metal screw with a proton beam oriented, first parallel and then perpendicular, to the longitudinal axis of the screw. The calculated dose profiles were compared with measured results from a plane-parallel ion chamber and Gafchromic EBT2 films. For the perpendicular setup, the measured dose immediately downstream from the screw exhibited dose enhancement up to 12% for SS and 8% for Ti, respectively, but such dose perturbation was not observed outside the lateral edges of the screws. The TPS showed 5% and 2% dose reductions immediately at the interface for the SS nd Ti screws, respectively, and up to 9% dose enhancements within 1 cm outside of the lateral edges of the screws. The measured dose enhancement was only observed within 5 mm from the interface along the beam path. At deeper depths, the lateral dose profiles appeared to be similar between the measurement and TPS, with dose reduction in the screw shadow region and dose enhancement within 1-2 cm outside of the lateral edges of the metals. For the parallel setup, no significant dose perturbation was detected at lateral distance beyond 3 mm away from both screws. Significant dose discrepancies exist between TPS calculations and ion chamber and film measurements in close proximity of high-Z inhomogeneities. The observed dose enhancement effect with proton therapy is not correctly modeled by TPS. An extra measure of caution should be taken when evaluating dosimetry with spinal metallic implants.

  15. Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Sofue, Keitaro; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Department of Radiology, Kobe, Hyogo (Japan); Yoshikawa, Takeshi; Ohno, Yoshiharu [Kobe University Graduate School of Medicine, Advanced Biomedical Imaging Research Center, Kobe, Hyogo (Japan); Kobe University Graduate School of Medicine, Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe, Hyogo (Japan); Negi, Noriyuki [Kobe University Hospital, Division of Radiology, Kobe, Hyogo (Japan); Inokawa, Hiroyasu; Sugihara, Naoki [Toshiba Medical Systems Corporation, Otawara, Tochigi (Japan)

    2017-07-15

    To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P < 0.0001). Liver and pancreas image qualities and visualizations of vasculature were significantly improved on CT with SEMAR (P < 0.0001) with substantial or almost perfect agreement (0.62 ≤ κ ≤ 0.83). SEMAR can improve image quality in abdominal CT in patients with small metal implants by reducing metallic artefacts. (orig.)

  16. Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm

    International Nuclear Information System (INIS)

    Sofue, Keitaro; Sugimura, Kazuro; Yoshikawa, Takeshi; Ohno, Yoshiharu; Negi, Noriyuki; Inokawa, Hiroyasu; Sugihara, Naoki

    2017-01-01

    To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P < 0.0001). Liver and pancreas image qualities and visualizations of vasculature were significantly improved on CT with SEMAR (P < 0.0001) with substantial or almost perfect agreement (0.62 ≤ κ ≤ 0.83). SEMAR can improve image quality in abdominal CT in patients with small metal implants by reducing metallic artefacts. (orig.)

  17. Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    J. Bornacelli

    2014-01-01

    Full Text Available Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs have become the main building block of silicon photonic (modulators, waveguide, source, and detectors. In this work, we present an approach based on implantation of Ag (or Au ions and a proper thermal annealing in order to improve the photoluminescence (PL emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 μm under surface. Once Si-NCs are formed inside the SiO2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs.

  18. The influence of direct laser metal sintering implants on the early stages of osseointegration in diabetic mini-pigs.

    Science.gov (United States)

    Tan, Naiwen; Liu, Xiangwei; Cai, Yanhui; Zhang, Sijia; Jian, Bo; Zhou, Yuchao; Xu, Xiaoru; Ren, Shuai; Wei, Hongbo; Song, Yingliang

    2017-01-01

    High failure rates of oral implants have been reported in diabetic patients due to the disruption of osseointegration. The aim of this study was to investigate whether direct laser metal sintering (DLMS) could improve osseointegration in diabetic animal models. Surface characterizations were carried out on two types of implants. Cell morphology and the osteogenic-related gene expression of MG63 cells were observed under conditions of DLMS and microarc oxidation (MAO). A diabetes model in mini-pigs was established by intravenous injection of streptozotocin (150 mg/kg), and a total of 36 implants were inserted into the mandibular region. Micro-computed tomography (micro-CT) and histologic evaluations were performed 3 and 6 months after implantation. The Ra (the average of the absolute height of all points) of MAO surface was 2.3±0.3 µm while the DLMS surface showed the Ra of 27.4±1.1 µm. The cells on DLMS implants spread out more podia than those on MAO implants through cell morphology analysis. Osteogenic-related gene expression was also dramatically increased in the DLMS group. Obvious improvement was observed in the micro-CT and Van Gieson staining analyses of DLMS implants compared with MAO at 3 months, although this difference disappeared by 6 months. DLMS implants showed a higher bone-implant contact percentage (33.2%±11.2%) at 3 months compared with MAO group (18.9%±7.3%) while similar results were showed at 6 months between DLMS group (42.8%±10.1%) and MAO group (38.3%±10.8%). The three-dimensional environment of implant surfaces with highly porous and fully interconnected channel and pore architectures can improve cell spreading and accelerate the progress of osseointegration in diabetic mini-pigs.

  19. Histological and biomechanical analysis of porous additive manufactured implants made by direct metal laser sintering: a pilot study in sheep.

    Science.gov (United States)

    Stübinger, Stefan; Mosch, Isabel; Robotti, Pierfrancesco; Sidler, Michéle; Klein, Karina; Ferguson, Stephen J; von Rechenberg, Brigitte

    2013-10-01

    It was the aim of this study to analyze osseointegrative properties of porous additive manufactured titanium implants made by direct metal laser sintering in a sheep model after an implantation period of 2 and 8 weeks. Three different types of implants were placed in the pelvis of six sheep. In each sheep were placed three standard machined (M), three sandblasted and etched (SE), and three porous additive manufactured (AM) implants. Of these three implants (one per type) were examined histologically and six implants were tested biomechanically. Additionally a semiquantitative histomorphometrical and qualitative fluorescent microscopic analysis were performed. After 2 and 8 weeks bone-to-implant-contact (BIC) values of the AM surface (2w: 20.49% ± 5.18%; 8w: 43.91% ± 9.69%) revealed no statistical significant differences in comparison to the M (2w: 20.33% ± 11.50%; 8w: 25.33% ± 4.61%) and SE (2w: 43.67 ± 12.22%; 8w: 53.33 ± 8.96%) surfaces. AM surface showed the highest increase of the BIC between the two observation time points. Considering the same implantation period histomorphometry and fluorescent labelling disclosed no significant differences in the bone surrounding the three implants groups. In contrast Removal-torque-test showed a significant improve in fixation strength (P ≤ 0.001) for the AM (1891.82 ± 308, 44 Nmm) surface after eight weeks in comparison to the M (198.93±88,04 Nmm) and SE (730.08 ± 151,89 Nmm) surfaces. All three surfaces (M, SE, and AM) showed sound osseointegration. AM implants may offer a possible treatment option in clinics for patients with compromised bone situations. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  20. Metal artifact reduction for flat panel detector intravenous CT angiography in patients with intracranial metallic implants after endovascular and surgical treatment.

    Science.gov (United States)

    Pjontek, Rastislav; Önenköprülü, Belgin; Scholz, Bernhard; Kyriakou, Yiannis; Schubert, Gerrit A; Nikoubashman, Omid; Othman, Ahmed; Wiesmann, Martin; Brockmann, Marc A

    2016-08-01

    Flat panel detector CT angiography with intravenous contrast agent injection (IV CTA) allows high-resolution imaging of cerebrovascular structures. Artifacts caused by metallic implants like platinum coils or clips lead to degradation of image quality and are a significant problem. To evaluate the influence of a prototype metal artifact reduction (MAR) algorithm on image quality in patients with intracranial metallic implants. Flat panel detector CT after intravenous application of 80 mL contrast agent was performed with an angiography system (Artis zee; Siemens, Forchheim, Germany) using a 20 s rotation protocol (200° rotation angle, 20 s acquisition time, 496 projections). The data before and after MAR of 26 patients with a total of 34 implants (coils, clips, stents) were independently evaluated by two blinded neuroradiologists. MAR improved the assessability of the brain parenchyma and small vessels (diameter metallic implants and at a distance of 6 cm (p<0.001 each, Wilcoxon test). Furthermore, MAR significantly improved the assessability of parent vessel patency and potential aneurysm remnants (p<0.005 each, McNemar test). MAR, however, did not improve assessability of stented vessels. When an intravenous contrast protocol is used, MAR significantly ameliorates the assessability of brain parenchyma, vessels, and treated aneurysms in patients with intracranial coils or clips. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  1. Effect of Extreme Wettability on Platelet Adhesion on Metallic Implants: From Superhydrophilicity to Superhydrophobicity.

    Science.gov (United States)

    Moradi, Sona; Hadjesfandiari, Narges; Toosi, Salma Fallah; Kizhakkedathu, Jayachandran N; Hatzikiriakos, Savvas G

    2016-07-13

    In order to design antithrombotic implants, the effect of extreme wettability (superhydrophilicity to superhydrophobicity) on the biocompatibility of the metallic substrates (stainless steel and titanium) was investigated. The wettability of the surface was altered by chemical treatments and laser ablation methods. The chemical treatments generated different functionality groups and chemical composition as evident from XPS analysis. The micro/nanopatterning by laser ablation resulted in three different pattern geometry and different surface roughness and consequently wettability. The patterned surface were further modified with chemical treatments to generate a wide range of surface wettability. The influence of chemical functional groups, pattern geometry, and surface wettability on protein adsorption and platelet adhesion was studied. On chemically treated flat surfaces, the type of hydrophilic treatment was shown to be a contributing factor that determines the platelet adhesion, since the hydrophilic oxidized substrates exhibit less platelet adhesion in comparison to the control untreated or acid treated surfaces. Also, the surface morphology, surface roughness, and superhydrophobic character of the surfaces are contributing factors to platelet adhesion on the surface. Our results show that superhydrophobic cauliflower-like patterns are highly resistant to platelet adhesion possibly due to the stability of Cassie-Baxter state for this pattern compared to others. Our results also show that simple surface treatments on metals offer a novel way to improve the hemocompatibility of metallic substrates.

  2. Fully refocused multi-shot spatiotemporally encoded MRI: robust imaging in the presence of metallic implants.

    Science.gov (United States)

    Ben-Eliezer, Noam; Solomon, Eddy; Harel, Elad; Nevo, Nava; Frydman, Lucio

    2012-12-01

    An approach has been recently introduced for acquiring arbitrary 2D NMR spectra or images in a single scan, based on the use of frequency-swept RF pulses for the sequential excitation and acquisition of the spins response. This spatiotemporal-encoding (SPEN) approach enables a unique, voxel-by-voxel refocusing of all frequency shifts in the sample, for all instants throughout the data acquisition. The present study investigates the use of this full-refocusing aspect of SPEN-based imaging in the multi-shot MRI of objects, subject to sizable field inhomogeneities that complicate conventional imaging approaches. 2D MRI experiments were performed at 7 T on phantoms and on mice in vivo, focusing on imaging in proximity to metallic objects. Fully refocused SPEN-based spin echo imaging sequences were implemented, using both Cartesian and back-projection trajectories, and compared with k-space encoded spin echo imaging schemes collected on identical samples under equal bandwidths and acquisition timing conditions. In all cases assayed, the fully refocused spatiotemporally encoded experiments evidenced a ca. 50 % reduction in signal dephasing in the proximity of the metal, as compared to analogous results stemming from the k-space encoded spin echo counterparts. The results in this study suggest that SPEN-based acquisition schemes carry the potential to overcome strong field inhomogeneities, of the kind that currently preclude high-field, high-resolution tissue characterizations in the neighborhood of metallic implants.

  3. Status report on the International Germanium Experiment

    International Nuclear Information System (INIS)

    Brodzinski, R.L.; Avignone, F.T.; Collar, J.I.; Courant, H.; Garcia, E.; Guerard, C.K.; Hensley, W.K.; Kirpichnikov, I.V.; Miley, H.S.; Morales, A.; Morales, J.; Nunez-Lagos, R.; Osetrov, S.B.; Pogosov, V.S.; Pomansky, A.A.; Puimedon, J.; Reeves, J.H.; Ruddick, K.; Saenz, C.; Salinas, A.; Sarsa, M.L.; Smolnikov, A.A.; Starostin, A.S.; Tamanyan, A.G.; Vasiliev, S.I.; Villar, J.A.

    1993-01-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic 7 Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported. (orig.)

  4. Status report on the International Germanium Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Brodzinski, R L; Avignone, F.T.; Collar, J I; Courant, H; Garcia, E; Guerard, C K; Hensley, W K; Kirpichnikov, I V; Miley, H S; Morales, A; Morales, J; Nunez-Lagos, R; Osetrov, S B; Pogosov, V S; Pomansky, A A; Puimedon, J; Reeves, J H; Ruddick, K; Saenz, C; Salinas, A; Sarsa, M L; Smolnikov, A A; Starostin, A S; Tamanyan, A G; Vasiliev, S I; Villar, J A [Pacific Northwest Lab., Richland, WA (United States) Univ. of South Carolina, Columbia, SC (United States) Univ. of Minnesota, Minneapolis, MN (United States) Univ. of Zaragoza (Spain) Inst. for Theoretical and Experimental Physics, Moscow (Russian Federation) Inst. for Nuclear Research, Baksan Neutrino Observatory (Russian Federation) Yerevan Physical Inst., Yerevan (Armenia)

    1993-04-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic [sup 7]Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported. (orig.)

  5. Laser and electron-beam powder-bed additive manufacturing of metallic implants: A review on processes, materials and designs.

    Science.gov (United States)

    Sing, Swee Leong; An, Jia; Yeong, Wai Yee; Wiria, Florencia Edith

    2016-03-01

    Additive manufacturing (AM), also commonly known as 3D printing, allows the direct fabrication of functional parts with complex shapes from digital models. In this review, the current progress of two AM processes suitable for metallic orthopaedic implant applications, namely selective laser melting (SLM) and electron beam melting (EBM) are presented. Several critical design factors such as the need for data acquisition for patient-specific design, design dependent porosity for osteo-inductive implants, surface topology of the implants and design for reduction of stress-shielding in implants are discussed. Additive manufactured biomaterials such as 316L stainless steel, titanium-6aluminium-4vanadium (Ti6Al4V) and cobalt-chromium (CoCr) are highlighted. Limitations and future potential of such technologies are also explored. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  6. Fatigue Fracture Strength of Implant-Supported Full Contour Zirconia and Metal Ceramic Fixed Partial Dentures

    Directory of Open Access Journals (Sweden)

    Fariborz Vafaee

    2017-10-01

    Full Text Available Objectives: Zirconia restorations have been suggested as a more durable and more appealing alternative to metal restorations. However, their mechanical properties may be negatively affected by fatigue due to superficial stresses or low temperature degradation. This study aimed to assess the fatigue fracture strength of three-unit implant-supported full contour zirconia and pre-sintered cobalt-chromium (Co-Cr alloy posterior fixed partial dentures (FPDs.Materials and Methods: In this in-vitro experimental study, 28 posterior three-unit implant-supported FPDs were fabricated of full contour zirconia and pre-sintered Co-Cr alloy, and were cemented on implant abutments. To simulate the oral environment, FPDs were subjected to 10,000 thermal cycles between 5-55°C for 30 seconds, and were then transferred to a chewing simulator (100,000 cycles, 50 N, 0.5 Hz. Afterwards, fatigue fracture strength was measured using a universal testing machine. Data were analyzed by Mann-Whitney U test.Results: The mean and standard deviation of fracture strength were 2108.6±440.1 N in full contour zirconia, and 3499.9±1106.5 N in pre-sintered Co-Cr alloy. According to Mann- Whitney U test, the difference in this respect was statistically significant between the two groups (P=0.007.Conclusions: Since the fracture strength values obtained in the two groups were significantly higher than the maximum mean masticatory load in the oral environment, both materials can be used for fabrication of posterior three-unit FPDs, depending on the esthetic demands of patients.

  7. Negative differential resistance effect induced by metal ion implantation in SiO2 film for multilevel RRAM application

    Science.gov (United States)

    Wu, Facai; Si, Shuyao; Shi, Tuo; Zhao, Xiaolong; Liu, Qi; Liao, Lei; Lv, Hangbing; Long, Shibing; Liu, Ming

    2018-02-01

    Pt/SiO2:metal nanoparticles/Pt sandwich structure is fabricated with the method of metal ion (Ag) implantation. The device exhibits multilevel storage with appropriate R off/R on ratio, good endurance and retention properties. Based on transmission electron microscopy and energy dispersive spectrometer analysis, we confirm that Pt nanoparticles are spurted into SiO2 film from Pt bottom electrode by Ag implantation; during electroforming, the local electric field can be enhanced by these Pt nanoparticles, meanwhile the Ag nanoparticles constantly migrate toward the Pt nanoparticles. The implantation induced nanoparticles act as trap sites in the resistive switching layer and play critical roles in the multilevel storage, which is evidenced by the negative differential resistance effect in the current-voltage (I-V) measurements.

  8. Materials and Techniques for Implantable Nutrient Sensing Using Flexible Sensors Integrated with Metal-Organic Frameworks.

    Science.gov (United States)

    Ling, Wei; Liew, Guoguang; Li, Ya; Hao, Yafeng; Pan, Huizhuo; Wang, Hanjie; Ning, Baoan; Xu, Hang; Huang, Xian

    2018-06-01

    The combination of novel materials with flexible electronic technology may yield new concepts of flexible electronic devices that effectively detect various biological chemicals to facilitate understanding of biological processes and conduct health monitoring. This paper demonstrates single- or multichannel implantable flexible sensors that are surface modified with conductive metal-organic frameworks (MOFs) such as copper-MOF and cobalt-MOF with large surface area, high porosity, and tunable catalysis capability. The sensors can monitor important nutriments such as ascorbicacid, glycine, l-tryptophan (l-Trp), and glucose with detection resolutions of 14.97, 0.71, 4.14, and 54.60 × 10 -6 m, respectively. In addition, they offer sensing capability even under extreme deformation and complex surrounding environment with continuous monitoring capability for 20 d due to minimized use of biological active chemicals. Experiments using live cells and animals indicate that the MOF-modified sensors are biologically safe to cells, and can detect l-Trp in blood and interstitial fluid. This work represents the first effort in integrating MOFs with flexible sensors to achieve highly specific and sensitive implantable electrochemical detection and may inspire appearance of more flexible electronic devices with enhanced capability in sensing, energy storage, and catalysis using various properties of MOFs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Lattice location of implanted transition metals in 3C–SiC

    CERN Document Server

    AUTHOR|(CDS)2085259; Wahl, Ulrich; Martins Correia, Joao; David Bosne, Eric; Amorim, Lígia; Silva, Daniel; Castro Ribeiro Da Silva, Manuel; Bharuth-Ram, Krishanlal; Da Costa Pereira, Lino Miguel

    2017-01-01

    We have investigated the lattice location of implanted transition metal (TM) 56Mn, 59Fe and 65Ni ions in undoped single-crystalline cubic 3C–SiC by means of the emission channeling technique using radioactive isotopes produced at the CERN-ISOLDE facility. We find that in the room temperature as-implanted state, most Mn, Fe and Ni atoms occupy carbon-coordinated tetrahedral interstitial sites (TC). Smaller TM fractions were also found on Si substitutional (SSi) sites. The TM atoms partially disappear from ideal-TC positions during annealing at temperatures between 500 °C and 700 °C, which is accompanied by an increase in the TM fraction occupying both SSi sites and random sites. An explanation is given according to what is known about the annealing mechanisms of silicon vacancies in silicon carbide. The origin of the observed lattice sites and their changes with thermal annealing are discussed and compared to the case of Si, highlighting the feature that the interstitial migration of TMs in SiC is much slo...

  10. Plasma immersion ion implantation (and deposition) inside metallic tubes of different dimensions and configurations

    Science.gov (United States)

    Ueda, M.; Silva, C.; Santos, N. M.; Souza, G. B.

    2017-10-01

    There is a strong need for developing methods to coat or implant ions inside metallic tubes for many practical contemporary applications, both for industry and science. Therefore, stainless steel tubes with practical diameters of 4, 11 and 16 cm, but short lengths of 20 cm, were internally treated by nitrogen plasma immersion ion implantation (PIII). Different configurations as tube with lid in one of the ends or both sides open were tested for better PIII performance, in the case of smallest diameter tube. Among these PIII tests in tubes, using the 4 cm diameter one with a lid, it was possible to achieve tube temperatures of more than 700 °C in 15 min and maintain it during the whole treatment time (typically 2 h). Samples made of different materials were placed at the interior of the tube, as the monitors for posterior analysis, and the tube was solely pulsed by high voltage pulser producing high voltage glow discharge and hollow cathode discharge both driven by a moderate power source. In this experiment, samples of SS 304, pure Ti, Ti6Al4V and Si were used for the tests of the above methods. Results on the analysis of the surface of these nitrogen PIII treated materials, as well as on their processing methods, are presented and discussed in the paper.

  11. MR imaging in the presence of small circular metallic implants. Assessment of thermal injuries

    International Nuclear Information System (INIS)

    Manner, I.; Alanen, A.; Komu, M.; Savunen, T.; Kantonen, I.; Ekfors, T.

    1996-01-01

    Purpose: The thermal effects of MR imaging in the presence of circular nonferromagnetic metallic implants were studied in 6 rabbits. Material and Methods: A sternotomy was performed and fixed with stainless steel wires, and small titanium rings (diameter 3 mm) were placed on the surface of the ascending aorta and subcutaneous tissue of the thigh. Four of the rabbits were exposed to an imaging procedure with a 1.5 T scanner applying a T1-weighted spin-echo sequence and a gradient echo sequence. Two of the animals served as unexposed controls. Thirty-six hours after the exposure, tissues adjacent to the implants were examined histologically and compared with corresponding samples of the control animals. Results: In the area of the titanium rings, histologic analysis revealed slight inflammatory changes apparently caused by the operation. No evidence of thermal injury was found, suggesting that the presence of the rings does not contraindicate MR examinations. Necrosis was noted in all of the sternal specimens. This was probably post-operative, but it impaired the assessment of thermal injury in this area. (orig.)

  12. PET/MRI in the presence of metal implants: Completion of the attenuation map from PET emission data

    DEFF Research Database (Denmark)

    Fuin, Niccolo; Pedemonte, Stefano; Catalano, Onofrio A.

    2017-01-01

    of radioactivity and attenuation from the emission data to determine the position, shape, and linear attenuation coefficient (LAC) of metallic implants. Methods: The initial estimate of the attenuation map was obtained using the MR Dixon method currently available on the Siemens Biograph mMR scanner...

  13. Evaluation of MRI artifacts caused by metallic dental implants and classification of the dental materials in use

    Czech Academy of Sciences Publication Activity Database

    Starčuk jr., Zenon; Bartušek, Karel; Hubálková, H.; Bachorec, T.; Starčuková, Jana; Krupa, P.

    2006-01-01

    Roč. 6, č. 2 (2006), s. 24-27 ISSN 1335-8871 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : magnetic resonance imaging * artifacts * metallic implants * dental alloys * magnetic susceptibility Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  14. The saturation phenomenon in Kr85 ion implantation in metallic targets

    International Nuclear Information System (INIS)

    Baptista Junior, V. de P.

    1978-01-01

    Noble gases, as Krypton containing the radioative isotope Kr 85 , can be stably incorporated into a wide variety of solids and used as tracers or a kind of sensitive probe to measure chemical and physical phenomena. A general review is presented about the methods of incorporation with emphasis on ion bombardment and saturation. The problem of saturation of metal targets was correlated to certain properties in order to get a mathematical approach. Six properties were chosen as more significative to produce a simple model of saturation on experiments of ion implantation with Kr 85 at 45 KeV. The accuracy of the model is limited by the experimental error, the available data and its own simplicity. (Author) [pt

  15. A Comparison of Implants Used in Open-Door Laminoplasty: Structural Rib Allografts Versus Metallic Miniplates.

    Science.gov (United States)

    Tabaraee, Ehsan; Mummaneni, Praveen; Abdul-Jabbar, Amir; Shearer, David; Roy, Esha; Amin, Beejal; Ames, Christopher; Burch, Shane; Deviren, Vedat; Berven, Sigurd; Hu, Serena; Chou, Dean; Tay, Bobby K

    2017-06-01

    A retrospective case-controlled study. Open-door laminoplasty has been successfully used to address cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament. Two common implants include rib allograft struts and metallic miniplates. The goals of this study were to compare outcomes, complications, and costs associated with these 2 implants. A retrospective review was done on 51 patients with allograft struts and 55 patients with miniplates. Primary outcomes were neck visual analog scale (VAS) pain scores and Nurick scores. Secondary outcomes included length of the procedure, estimated blood loss, rates of complications, and the direct costs associated with the surgery and inpatient hospitalization. There were no differences in demographic characteristics, diagnoses, comorbidities, and preoperative outcome scores between the 2 treatment groups. Mean follow-up was 27 months. The postoperative neck VAS scores and Nurick scores improved significantly from baseline to final follow-up for both groups, but there was no difference between the 2 groups. The average length of operation (161 vs. 136 min) and number of foraminotomies (2.7 vs. 1.3) were higher for the allograft group (P=0.007 and 0.0001, respectively). Among the miniplate group, there was no difference in complications but a trend for less neck pain for patients treated without hard collar at final follow-up (1.8 vs. 2.3, P=0.52). The mean direct costs of hospitalization for the miniplate group were 15% higher. Structural rib allograft struts and metallic miniplates result in similar improvements in pain and functional outcome scores with no difference in the rate of complications in short-term follow-up. Potential benefits of using a plate include shorter procedure length and less need for postoperative immobilization. When costs of bracing and operative time are included, the difference in cost between miniplates and allograft struts is negligible.

  16. Thermal recrystallization of physical vapor deposition based germanium thin films on bulk silicon (100)

    KAUST Repository

    Hussain, Aftab M.

    2013-08-16

    We demonstrate a simple, low-cost, and scalable process for obtaining uniform, smooth surfaced, high quality mono-crystalline germanium (100) thin films on silicon (100). The germanium thin films were deposited on a silicon substrate using plasma-assisted sputtering based physical vapor deposition. They were crystallized by annealing at various temperatures ranging from 700 °C to 1100 °C. We report that the best quality germanium thin films are obtained above the melting point of germanium (937 °C), thus offering a method for in-situ Czochralski process. We show well-behaved high-κ /metal gate metal-oxide-semiconductor capacitors (MOSCAPs) using this film. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Ross filter pairs for metal artefact reduction in x-ray tomography: a case study based on imaging and segmentation of metallic implants

    Science.gov (United States)

    Arhatari, Benedicta D.; Abbey, Brian

    2018-01-01

    Ross filter pairs have recently been demonstrated as a highly effective means of producing quasi-monoenergetic beams from polychromatic X-ray sources. They have found applications in both X-ray spectroscopy and for elemental separation in X-ray computed tomography (XCT). Here we explore whether they could be applied to the problem of metal artefact reduction (MAR) for applications in medical imaging. Metal artefacts are a common problem in X-ray imaging of metal implants embedded in bone and soft tissue. A number of data post-processing approaches to MAR have been proposed in the literature, however these can be time-consuming and sometimes have limited efficacy. Here we describe and demonstrate an alternative approach based on beam conditioning using Ross filter pairs. This approach obviates the need for any complex post-processing of the data and enables MAR and segmentation from the surrounding tissue by exploiting the absorption edge contrast of the implant.

  18. Evaluation of MR issues for the latest standard brands of orthopedic metal implants: plates and screws.

    Science.gov (United States)

    Zou, Yue-Fen; Chu, Bin; Wang, Chuan-Bing; Hu, Zhi-Yi

    2015-03-01

    The study was performed to evaluate magnetic resonance (MR) issues for the latest standard brands of plates and screws used in orthopedic surgery at a 1.5-T MR system, including the safety and metallic artifacts. The plates and screws (made of titanium alloy and stainless steel materials, according to the latest standard brands) were assessed for displacement in degrees, MRI-related heating and artifacts at a 1.5-T MR system. The displacement in degrees of the plates and screws was evaluated on an angel-measurement instrument at the entrance of the MR scanner. The MRI-related heating was assessed on a swine leg fixed with a plate by using a "worst-case" pulse sequence. A rectangular water phantom was designed to evaluate metallic artifacts of a screw on different sequences (T1/T2-weighted FSE, STIR, T2-FSE fat saturation, GRE, DWI) and then artifacts were evaluated on T2-weighted FSE sequence by modifying the scanning parameters including field of view (FOV), echo train length (ETL) and bandwidth to identify the influence of parameters on metallic artifacts. 15 volunteers with internal vertebral fixation (titanium alloy materials) were scanned with MR using axial and sagittal T2-FSE, sagittal T2-FSE fat suppression and STIR with conventional and optimized parameters, respectively. Then all images were graded by two experienced radiologists having the experience of more than 7 years under double-blind studies that is neither of them knew which was conventional parameter group and optimized parameter group. The average deflection angle of titanium alloy and stainless steel implants were 4.3° and 7.7°, respectively, (less than 45°) which indicated that the magnetically induced force was less than the weight of the object. The deflection angle of the titanium alloy implants was less than the stainless steel one (t=9.69, Ptitanium alloy before and after the scan was 0.48°C and stainless steel implants was 0.74°C, respectively, with the background temperature

  19. PET/MRI in the Presence of Metal Implants: Completion of the Attenuation Map from PET Emission Data.

    Science.gov (United States)

    Fuin, Niccolo; Pedemonte, Stefano; Catalano, Onofrio A; Izquierdo-Garcia, David; Soricelli, Andrea; Salvatore, Marco; Heberlein, Keith; Hooker, Jacob M; Van Leemput, Koen; Catana, Ciprian

    2017-05-01

    We present a novel technique for accurate whole-body attenuation correction in the presence of metallic endoprosthesis, on integrated non-time-of-flight (non-TOF) PET/MRI scanners. The proposed implant PET-based attenuation map completion (IPAC) method performs a joint reconstruction of radioactivity and attenuation from the emission data to determine the position, shape, and linear attenuation coefficient (LAC) of metallic implants. Methods: The initial estimate of the attenuation map was obtained using the MR Dixon method currently available on the Siemens Biograph mMR scanner. The attenuation coefficients in the area of the MR image subjected to metal susceptibility artifacts are then reconstructed from the PET emission data using the IPAC algorithm. The method was tested on 11 subjects presenting 13 different metallic implants, who underwent CT and PET/MR scans. Relative mean LACs and Dice similarity coefficients were calculated to determine the accuracy of the reconstructed attenuation values and the shape of the metal implant, respectively. The reconstructed PET images were compared with those obtained using the reference CT-based approach and the Dixon-based method. Absolute relative change (aRC) images were generated in each case, and voxel-based analyses were performed. Results: The error in implant LAC estimation, using the proposed IPAC algorithm, was 15.7% ± 7.8%, which was significantly smaller than the Dixon- (100%) and CT- (39%) derived values. A mean Dice similarity coefficient of 73% ± 9% was obtained when comparing the IPAC- with the CT-derived implant shape. The voxel-based analysis of the reconstructed PET images revealed quantification errors (aRC) of 13.2% ± 22.1% for the IPAC- with respect to CT-corrected images. The Dixon-based method performed substantially worse, with a mean aRC of 23.1% ± 38.4%. Conclusion: We have presented a non-TOF emission-based approach for estimating the attenuation map in the presence of metallic implants, to

  20. SIMS as a new methodology to depth profile helium in as-implanted and annealed pure bcc metals?

    Energy Technology Data Exchange (ETDEWEB)

    Gorondy-Novak, S. [CEA, DEN, Service de Recherches de Métallurgie Physique, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France); Jomard, F. [Groupe d' Etude de la Matière Condensée, CNRS, UVSQ, 45 avenue des Etats-Unis, 78035 Versailles cedex (France); Prima, F. [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Lefaix-Jeuland, H., E-mail: helene.lefaix@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France)

    2017-05-01

    Reliable He profiles are highly desirable for better understanding helium behavior in materials for future nuclear applications. Recently, Secondary Ions Mass Spectrometry (SIMS) allowed the characterization of helium distribution in as-implanted metallic systems. The Cs{sup +} primary ion beam coupled with CsHe{sup +} molecular detector appeared to be a promising technique which overcomes the very high He ionization potential. In this study, {sup 4}He depth profiles in pure body centered cubic (bcc) metals (V, Fe, Ta, Nb and Mo) as-implanted and annealed, were obtained by SIMS. All as-implanted samples exhibited a projected range of around 200 nm, in agreement with SRIM theoretical calculations. After annealing treatment, SIMS measurements evidenced the evolution of helium depth profile with temperature. The latter SIMS results were compared to the helium bubble distribution obtained by Transmission Electron Microscopy (TEM). This study confirmed the great potential of this experimental procedure as a He-depth profiling technique in bcc metals. Indeed, the methodology described in this work could be extended to other materials including metallic and non-metallic compounds. Nevertheless, the quantification of helium concentration after annealing treatment by SIMS remains uncertain probably due to the non-uniform ionization efficiency in samples containing large bubbles.

  1. Cobalt deposition in mineralized bone tissue after metal-on-metal hip resurfacing: Quantitative μ-X-ray-fluorescence analysis of implant material incorporation in periprosthetic tissue.

    Science.gov (United States)

    Hahn, Michael; Busse, Björn; Procop, Mathias; Zustin, Jozef; Amling, Michael; Katzer, Alexander

    2017-10-01

    Most resurfacing systems are manufactured from cobalt-chromium alloys with metal-on-metal (MoM) bearing couples. Because the quantity of particulate metal and corrosion products which can be released into the periprosthetic milieu is greater in MoM bearings than in metal-on-polyethylene (MoP) bearings, it is hypothesized that the quantity and distribution of debris released by the MoM components induce a compositional change in the periprosthetic bone. To determine the validity of this claim, nondestructive µ-X-ray fluorescence analysis was carried out on undecalcified histological samples from 13 femoral heads which had undergone surface replacement. These samples were extracted from the patients after gradient time points due to required revision surgery. Samples from nonintervened femoral heads as well as from a MoP resurfaced implant served as controls. Light microscopy and µ-X-ray fluorescence analyses revealed that cobalt debris was found not only in the soft tissue around the prosthesis and the bone marrow, but also in the mineralized bone tissue. Mineralized bone exposed to surface replacements showed significant increases in cobalt concentrations in comparison with control specimens without an implant. A maximum cobalt concentration in mineralized hard tissue of up to 380 ppm was detected as early as 2 years after implantation. Values of this magnitude are not found in implants with a MoP surface bearing until a lifetime of more than 20 years. This study demonstrates that hip resurfacing implants with MoM bearings present a potential long-term health risk due to rapid cobalt ion accumulation in periprosthetic hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1855-1862, 2017. © 2016 Wiley Periodicals, Inc.

  2. Risk assessment of electromagnetic fields exposure with metallic orthopedic implants: a cadaveric study.

    Science.gov (United States)

    Crouzier, D; Selek, L; Martz, B-A; Dabouis, V; Arnaud, R; Debouzy, J-C

    2012-02-01

    Metallic materials are well known to strongly interact with electromagnetic fields. While biological effects of such field have been extensively studied, only few works dealt with the interactions of electromagnetic waves with passive metallic device implanted in biological system. Hence only several numerical and phantom simulation studies were focusing on this aspect, whereas no in situ anatomic experiment has been previously performed. In this study the effect of electromagnetic waves on eight different orthopaedic medical devices (six plates from 55 to 318mm length, a total knee and a total hip prosthesis) were explored on six human cadavers. To mimic a random environmental exposure resulting from the most common frequencies band used in domestic environment and medical applications (TV and radio broadcasting, cell phone communication, MRI, diathermy treatment), a multifrequency generator emitting in VHF, UHF, GSM and GCS frequency bands was used. The different medical devices were exposed to an electromagnetic field at 50W/m(2) and 100W/m(2). After 6min exposure, the temperature was measured on three points close to each medical device, and the induced currents were estimated. No significant temperature increase (<0.2°C) was finally detected; beside, a slight induced tension (up to 1.1V) was recorded but would appear too low to induce any biological side effect. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  3. Surface modification of orthodontic implants by nanocomposite coatings based on chitosan and metals

    Directory of Open Access Journals (Sweden)

    Suetenkov D.Ye.

    2013-09-01

    Full Text Available Purpose: to study the properties of nanostructured coatings in orthodontic implants. Material and methods. Low and average molecular mass chitosan, 3-amynopropil-3-methoxysylan and suspensions of 5 nm and 10 nm gold nano-spheres stabilized with natrium citrate were used for nanocomposed surfaces. 2mg/ml polyethylenamin water solution was used for making the underlayer before putting polyion coverage using «POLYION-1M». The polyion covering dynamics was studied by polyquartz weighing method. Morphology of created layers was studied with atomic microscopy, elements were studied by secondary ion mass-spectrometry. Results. The best transmission among structures of chito-san/metals was showed by low molecular mass of chitosan and 8-1 Onm nanoparticles of metals. Analysis of roughness of surface shows that nanoparticles of gold make the most solid surface on 3-amynopropil-3-methoxysylan underlayer. Conclusion. The development of biocomparative materials in maxillofacial surgery is considered to be effective method of decreasing the risk of post-operative inflammatory complications by local antibacterial effect.

  4. Evaluation of MR issues for the latest standard brands of orthopedic metal implants: Plates and screws

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Yue-fen, E-mail: zou_yf@163.com [Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing (China); Chu, Bin, E-mail: 18262636700@163.com [Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing (China); Wang, Chuan-bing, E-mail: wangchuanb_csr@163.com [Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing (China); Hu, Zhi-yi, E-mail: huzhiyi@medmail.com.cn [Department of Spine Surgery, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing (China)

    2015-03-15

    Highlights: •Although previous studies have indicated that most of the orthopedic implants are compatible in MR imaging system especially for titanium alloy, there are still concerns about the safety of patients with stainless steel implants, who were refused to a MR scan in most cases in our country. •In this study, it was verified that both titanium alloy and stainless steel materials (plates and screws) cause a weak force and low MRI-related heating at a 1.5-T or less, which do not pose an additional hazard or risk to patients. In addition, we also had explored the influence of different sequences and parameters on size of metallic artifacts to obtain optimized pulse sequences with appropriate parameters for reducing artifacts, which would be convenient and useful in clinical work. -- Abstract: Purpose: The study was performed to evaluate magnetic resonance (MR) issues for the latest standard brands of plates and screws used in orthopedic surgery at a 1.5-T MR system, including the safety and metallic artifacts. Methods: The plates and screws (made of titanium alloy and stainless steel materials, according to the latest standard brands) were assessed for displacement in degrees, MRI-related heating and artifacts at a 1.5-T MR system. The displacement in degrees of the plates and screws was evaluated on an angel-measurement instrument at the entrance of the MR scanner. The MRI-related heating was assessed on a swine leg fixed with a plate by using a “worst-case” pulse sequence. A rectangular water phantom was designed to evaluate metallic artifacts of a screw on different sequences (T1/T2-weighted FSE, STIR, T2-FSE fat saturation, GRE, DWI) and then artifacts were evaluated on T2-weighted FSE sequence by modifying the scanning parameters including field of view (FOV), echo train length (ETL) and bandwidth to identify the influence of parameters on metallic artifacts. 15 volunteers with internal vertebral fixation (titanium alloy materials) were scanned

  5. Evaluation of MR issues for the latest standard brands of orthopedic metal implants: Plates and screws

    International Nuclear Information System (INIS)

    Zou, Yue-fen; Chu, Bin; Wang, Chuan-bing; Hu, Zhi-yi

    2015-01-01

    Highlights: •Although previous studies have indicated that most of the orthopedic implants are compatible in MR imaging system especially for titanium alloy, there are still concerns about the safety of patients with stainless steel implants, who were refused to a MR scan in most cases in our country. •In this study, it was verified that both titanium alloy and stainless steel materials (plates and screws) cause a weak force and low MRI-related heating at a 1.5-T or less, which do not pose an additional hazard or risk to patients. In addition, we also had explored the influence of different sequences and parameters on size of metallic artifacts to obtain optimized pulse sequences with appropriate parameters for reducing artifacts, which would be convenient and useful in clinical work. -- Abstract: Purpose: The study was performed to evaluate magnetic resonance (MR) issues for the latest standard brands of plates and screws used in orthopedic surgery at a 1.5-T MR system, including the safety and metallic artifacts. Methods: The plates and screws (made of titanium alloy and stainless steel materials, according to the latest standard brands) were assessed for displacement in degrees, MRI-related heating and artifacts at a 1.5-T MR system. The displacement in degrees of the plates and screws was evaluated on an angel-measurement instrument at the entrance of the MR scanner. The MRI-related heating was assessed on a swine leg fixed with a plate by using a “worst-case” pulse sequence. A rectangular water phantom was designed to evaluate metallic artifacts of a screw on different sequences (T1/T2-weighted FSE, STIR, T2-FSE fat saturation, GRE, DWI) and then artifacts were evaluated on T2-weighted FSE sequence by modifying the scanning parameters including field of view (FOV), echo train length (ETL) and bandwidth to identify the influence of parameters on metallic artifacts. 15 volunteers with internal vertebral fixation (titanium alloy materials) were scanned

  6. Stent implantation into the tracheo-bronchial system in rabbits: histopathologic sequelae in bare metal vs. drug-eluting stents.

    Science.gov (United States)

    Sigler, Matthias; Klötzer, Julia; Quentin, Thomas; Paul, Thomas; Möller, Oliver

    2015-12-01

    Stent implantation into the tracheo-bronchial system may be life-saving in selected pediatric patients with otherwise intractable stenosis of the upper airways. Following implantation, significant tissue proliferation may occur, requiring re-interventions. We sought to evaluate the effect of immunosuppressive coating of the stents on the extent of tissue proliferation in an animal model. Bare metal and sirolimus-coated stents (Bx Sonic and Cypher Select, Johnson & Johnson, Cordis) were implanted into non-stenotic lower airways of New Zealand white rabbits (weight 3.1 to 4.8 kg). Three stents with sirolimus coating and six bare metal stents could be analyzed by means of histology and immunohistochemistry 12 months after implantation. On a macroscopic evaluation, all stents were partially covered with a considerable amount of whitish tissue. Histologically, these proliferations contained fiber-rich connective tissue and some fibromuscular cells without significant differences between both stent types. The superficial tissue layer was formed by typical respiratory epithelium and polygonal cells. Abundant lymphocyte infiltrations and moderate granulocyte infiltrations were found in both groups correspondingly, whereas foreign-body reaction was more pronounced around sirolimus-eluting stents. After stent implantation in the tracheo-bronchial system of rabbits, we found tissue reactions comparable to those seen after stent implantation into the vascular system. There was no difference between coated and uncoated stents with regard to quality and quantity of tissue proliferation. We found, however, a significantly different inflammatory reaction with a more pronounced foreign-body reaction in sirolimus-coated stents. In our small series, drug-eluting stents did not exhibit any benefit over bare metal stents in an experimental setting.

  7. In vitro assessment of tissue heating near metallic medical implants by exposure to pulsed radio frequency diathermy

    International Nuclear Information System (INIS)

    Ruggera, P S; Witters, D M; Maltzahn, G von; Bassen, H I

    2003-01-01

    A patient with bilateral implanted neurostimulators suffered significant brain tissue damage, and subsequently died, following diathermy treatment to hasten recovery from teeth extraction. Subsequent MRI examinations showed acute deterioration of the tissue near the deep brain stimulator (DBS) lead's electrodes which was attributed to excessive tissue heating induced by the diathermy treatment. Though not published in the open literature, a second incident was reported for a patient with implanted neurostimulators for the treatment of Parkinson's disease. During a diathermy treatment for severe kyphosis, the patient had a sudden change in mental status and neurological deficits. The diathermy was implicated in causing damage to the patient's brain tissue. To investigate if diathermy induced excessive heating was possible with other types of implantable lead systems, or metallic implants in general, we conducted a series of in vitro laboratory tests. We obtained a diathermy unit and also assembled a controllable laboratory exposure system. Specific absorption rate (SAR) measurements were performed using fibre optic thermometry in proximity to the implants to determine the rate of temperature rise using typical diathermy treatment power levels. Comparisons were made of the SAR measurements for a spinal cord stimulator (SCS) lead, a pacemaker lead and three types of bone prosthesis (screws, rods and a plate). Findings indicate that temperature changes of 2.54 and 4.88 deg. C s -1 with corresponding SAR values of 9129 and 17 563 W kg -1 near the SCS and pacemaker electrodes are significantly higher than those found in the proximity of the other metallic implants which ranged from 0.04 to 0.69 deg C s -1 (129 to 2471 W kg -1 ). Since the DBS leads that were implanted in the reported human incidents have one-half the electrode surface area of the tested SCS lead, these results imply that tissue heating at rates at least equal to or up to twice as much as those reported

  8. The formation of an organic coat and the release of corrosion microparticles from metallic magnesium implants.

    Science.gov (United States)

    Badar, Muhammad; Lünsdorf, Heinrich; Evertz, Florian; Rahim, Muhammad Imran; Glasmacher, Birgit; Hauser, Hansjörg; Mueller, Peter P

    2013-07-01

    Magnesium alloys have been proposed as prospective degradable implant materials. To elucidate the complex interactions between the corroding implants and the tissue, magnesium implants were analyzed in a mouse model and the response was compared to that induced by Ti and by the resorbable polymer polyglactin, respectively. One month after implantation, distinct traces of corrosion were apparent but the magnesium implants were still intact, whereas resorbable polymeric wound suture implants were already fragmented. Analysis of magnesium implants 2weeks after implantation by energy-dispersive X-ray spectroscopy indicated that magnesium, oxygen, calcium and phosphate were present at the implant surface. One month after implantation, the element composition of the outermost layer of the implant was indicative of tissue without detectable levels of magnesium, indicating a protective barrier function of this organic layer. In agreement with this notion, gene expression patterns in the surrounding tissue were highly similar for all implant materials investigated. However, high-resolution imaging using energy-filtered transmission electron microscopy revealed magnesium-containing microparticles in the tissue in the proximity of the implant. The release of such corrosion particles may contribute to the accumulation of calcium phosphate in the nearby tissue and to bone conductive activities of magnesium implants. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Moving metal artifact reduction in cone-beam CT scans with implanted cylindrical gold markers

    International Nuclear Information System (INIS)

    Toftegaard, Jakob; Fledelius, Walther; Worm, Esben S.; Poulsen, Per R.; Seghers, Dieter; Huber, Michael; Brehm, Marcus; Elstrøm, Ulrik V.

    2014-01-01

    Purpose: Implanted gold markers for image-guided radiotherapy lead to streaking artifacts in cone-beam CT (CBCT) scans. Several methods for metal artifact reduction (MAR) have been published, but they all fail in scans with large motion. Here the authors propose and investigate a method for automatic moving metal artifact reduction (MMAR) in CBCT scans with cylindrical gold markers. Methods: The MMAR CBCT reconstruction method has six steps. (1) Automatic segmentation of the cylindrical markers in the CBCT projections. (2) Removal of each marker in the projections by replacing the pixels within a masked area with interpolated values. (3) Reconstruction of a marker-free CBCT volume from the manipulated CBCT projections. (4) Reconstruction of a standard CBCT volume with metal artifacts from the original CBCT projections. (5) Estimation of the three-dimensional (3D) trajectory during CBCT acquisition for each marker based on the segmentation in Step 1, and identification of the smallest ellipsoidal volume that encompasses 95% of the visited 3D positions. (6) Generation of the final MMAR CBCT reconstruction from the marker-free CBCT volume of Step 3 by replacing the voxels in the 95% ellipsoid with the corresponding voxels of the standard CBCT volume of Step 4. The MMAR reconstruction was performed retrospectively using a half-fan CBCT scan for 29 consecutive stereotactic body radiation therapy patients with 2–3 gold markers implanted in the liver. The metal artifacts of the MMAR reconstructions were scored and compared with a standard MAR reconstruction by counting the streaks and by calculating the standard deviation of the Hounsfield units in a region around each marker. Results: The markers were found with the same autosegmentation settings in 27 CBCT scans, while two scans needed slightly changed settings to find all markers automatically in Step 1 of the MMAR method. MMAR resulted in 15 scans with no streaking artifacts, 11 scans with 1–4 streaks, and 3 scans

  10. Transition Metal Ion Implantation into Diamond-Like Carbon Coatings: Development of a Base Material for Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Andreas Markwitz

    2015-01-01

    Full Text Available Micrometre thick diamond-like carbon (DLC coatings produced by direct ion deposition were implanted with 30 keV Ar+ and transition metal ions in the lower percentage (<10 at.% range. Theoretical calculations showed that the ions are implanted just beneath the surface, which was confirmed with RBS measurements. Atomic force microscope scans revealed that the surface roughness increases when implanted with Ar+ and Cu+ ions, whereas a smoothing of the surface from 5.2 to 2.7 nm and a grain size reduction from 175 to 93 nm are measured for Ag+ implanted coatings with a fluence of 1.24×1016 at. cm−2. Calculated hydrogen and carbon depth profiles showed surprisingly significant changes in concentrations in the near-surface region of the DLC coatings, particularly when implanted with Ag+ ions. Hydrogen accumulates up to 32 at.% and the minimum of the carbon distribution is shifted towards the surface which may be the cause of the surface smoothing effect. The ion implantations caused an increase in electrical conductivity of the DLC coatings, which is important for the development of solid-state gas sensors based on DLC coatings.

  11. Advanced characterization of carrier profiles in germanium using micro-machined contact probes

    DEFF Research Database (Denmark)

    Clarysse, T.; Konttinen, M.; Parmentier, B.

    2012-01-01

    of new concepts based on micro machined, closely spaced contact probes (10 μm pitch). When using four probes to perform sheet resistance measurements, a quantitative carrier profile extraction based on the evolution of the sheet resistance versus depth along a beveled surface is obtained. Considering...... the properties of both approaches on Al+ implants in germanium with different anneal treatments....

  12. Pragmatic approach to the clinical work-up of patients with putative allergic disease to metallic orthopaedic implants before and after surgery

    DEFF Research Database (Denmark)

    Thyssen, J P; Menné, T; Schalock, P C

    2011-01-01

    on in the work-up of patients with putative allergic complications following surgery. Few studies have investigated whether subjects with metal contact allergy have increased risk of developing complications following orthopaedic implant insertion. Metal allergy might in a minority increase the risk...... testing prior to surgery unless the patient has already had implant surgery with complications suspected to be allergic or has a history of clinical metal intolerance of sufficient magnitude to be of concern to the patient or a health provider. The clinical work-up of a patient suspected of having......Allergic complications following insertion of metallic orthopaedic implants include allergic dermatitis reactions but also extracutaneous complications. As metal-allergic patients and/or surgeons may ask dermatologists and allergologists for advice prior to planned orthopaedic implant surgery...

  13. Assessment of magnetic field interactions and radiofrequency‐radiation‐induced heating of metallic spinal implants in 7 T field

    Science.gov (United States)

    Tsukimura, Itsuko; Sasaki, Makoto; Endo, Hirooki; Yamabe, Daisuke; Oikawa, Ryosuke; Doita, Minoru

    2017-01-01

    ABSTRACT The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross‐linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15‐min‐long fast spin‐echo and balanced gradient‐echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0–21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0–6.3° [2.2°]). Among the metallic rods, the cobalt–chrome rods had significantly larger deflection angles (17.8–21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0–7.7° [6.2°]). The temperature changes of the implants, including the cross‐linked rods, were 0.7–1.0°C [0.8°C] and 0.6–1.0°C [0.7°C] during the fast spin‐echo and balanced gradient‐echo sequences, respectively; these changes were slightly larger than those of the controls (0.4–1.1°C [0.5°C] and 0.3–0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1831–1837, 2017. PMID:27769107

  14. Assessment of magnetic field interactions and radiofrequency-radiation-induced heating of metallic spinal implants in 7 T field.

    Science.gov (United States)

    Tsukimura, Itsuko; Murakami, Hideki; Sasaki, Makoto; Endo, Hirooki; Yamabe, Daisuke; Oikawa, Ryosuke; Doita, Minoru

    2017-08-01

    The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross-linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15-min-long fast spin-echo and balanced gradient-echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0-21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0-6.3° [2.2°]). Among the metallic rods, the cobalt-chrome rods had significantly larger deflection angles (17.8-21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0-7.7° [6.2°]). The temperature changes of the implants, including the cross-linked rods, were 0.7-1.0°C [0.8°C] and 0.6-1.0°C [0.7°C] during the fast spin-echo and balanced gradient-echo sequences, respectively; these changes were slightly larger than those of the controls (0.4-1.1°C [0.5°C] and 0.3-0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1831-1837, 2017. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.

  15. Bioavailability of heavy metals, germanium and rare earth elements at Davidschacht dump-field in mine affected area of Freiberg (Saxony)

    Science.gov (United States)

    Midula, Pavol; Wiche, Oliver

    2016-04-01

    Bioavailability research presents an essential tool, in modern phytoremediation and phytomining technologies, allowing the estimation of plant available fractions of elements in soils. However, up to date, sufficient interdisciplinary knowledge on the biogeochemically impacted behavior of specific target elements, in particular Ge and REEs in mining affected soils and their uptake into strategically used plants is lacking. This presented work is focused on a correlation study between the concentrations of selected heavy metals, Ge and REEs in soils formed on the top of the dump-field of Davidschacht and the corresponding their concentrations in 12 vascular plant species. The mine-dump of Davidschacht, situated in the Freiberg (Saxony, Germany) municipality area was chosen as the study area, which has been considered to be a high contaminated enclave, due to the mining history of the region. In total 12 sampling sites with differing composition of plant species were selected. At each sampling site soil samples from a soil depth of 0 - 10 cm and samples of plant material (shoots) were taken. The soil samples were analysed for total concentration of elements, pH (H2O) and consequently analysed by 4-step sequential extraction (SE) to determine fractions of elements that are mobile (fraction 1), acid soluble (pH 5) (fraction 2), bound to organic and oxidizable matter (fraction 3) and bound to amorphic oxides (fraction 4). The plant material was decomposed by hydrofluoric acid in order to extract the elements. Concentrations of elements in soil extracts and digestion solutions were analysed by ICP-MS. For all species bioconcentration factor (BCF) was calculated of the total concentration of elements in order to investigate the bioaccumulation potential. Arsenic (As), cadmium (Cd) and lead (Pb) were chosen as the representative heavy metals. Within the REEs neodymium (Nd) and cerium (Ce) were selected as representatives for all REEs, since Nd and Ce correlated significant

  16. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies.

    Science.gov (United States)

    Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John; Bonomo, Lorenzo

    2015-09-01

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging.

  17. Lab-based x-ray tomography of a cochlear implant using energy discriminating detectors for metal artefact reduction

    Science.gov (United States)

    Yokhana, Viona S. K.; Arhatari, Benedicta D.; Gureyev, Timur E.; Abbey, Brian

    2018-01-01

    X-ray computed tomography (XCT) is an important clinical diagnostic tool which is also used in a range of biological imaging applications in research. The increasing prevalence of metallic implants in medical and dental radiography and tomography has driven the demand for new approaches to solving the issue of metal artefacts in XCT. Metal artefacts occur when a highly absorbing material is imaged which is in boundary contact with one or more weakly absorbing components, such as soft-tissue. The resulting `streaking' in the reconstructed images creates significant challenges for X-ray analysis due to the non-linear dependence on the absorption properties of the sample. In this paper we introduce a new approach to removing metal artefacts which exploits the capabilities of the recently available, photon-counting PiXirad detector. Our approach works for standard lab-based polychromatic X-ray tubes and does not rely on any postprocessing of the data. The method is demonstrated using both simulated data from a test phantom and experimental data collected from a cochlear implant. The results show that by combining the individual images, which are simultaneously generated for each different energy threshold, artefact -free segmentation of the implant from the surrounding biological tissue is achieved.

  18. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

    International Nuclear Information System (INIS)

    Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John

    2015-01-01

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

  19. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

    Energy Technology Data Exchange (ETDEWEB)

    Filograna, Laura [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland); Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Guggenberger, Roman; Winklhofer, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Thali, Michael John [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland)

    2015-09-15

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

  20. Metallic stent implantation in the treatment of malignant tracheal stenosis under general anaesthesia

    International Nuclear Information System (INIS)

    Bai Xuming; Jin Yong; Xie Hong; Cheng Long; Gu Xingshi; Chang Liuhui

    2012-01-01

    Objective: To evaluate the safety and feasibility of the tracheal stent implantation for treatment of malignant tracheal stenosis under general anaesthesia. Methods: Eighteen patients with malignant tracheal stenosis underwent preoperative 64-slice spiral CT scan and airway reconstruction. The stenotic sites were located in main tracheal trunk (5 patients), in right main bronchus (1 patient), in trachea and left main bronchus (4 patients), in trachea and right main bronchus (3 patients), in main tracheal trunk and bilateral main bronchus (5 patients). The degree of stenosis was rated 51% to 70% in 7 cases, 71% to 90% in 11 cases. All patients, 17 patients of ASA grade Ⅳ and 1 patient of grade Ⅲ, presented with severe dyspnea. Under general anaesthesia, implantation of metallic stent was performed through the sputum aspiration hole of the connecting tubing with DSA guidance. The NBP, ECG, RR, SaO 2 of the patients were recorded and compared with t test during the entire procedure. At the end of the procedure, relief of dyspnea, complications related to anesthesia and operation were recorded. Results: The success rate of stent placement was 18/18, and dyspnea was significantly relived in all patients. Slightly bloody sputum occurred in 7 cases. The stent was obstructed by sputum in 1 case,and the patient was treated with medication. There were no severe complications. The operative course were rated 11 to 9 in 17 cases, and 6 to 8 in 1 case. All 18 patients were cooperative during the procedure. Sixteen patients rated the procedure as very comfortable and 2 rated the procedure as comfortable. Respiratory rate (RR) and heart rate (HR) decreased in all patients after the operation [(37.1 ± 2.8)/min and (106.5 ± 14.2) bpm before the operation respectively, (18.6 ± 1.4)/min and (73.2 ± 7.6) bpm after the operation respectively], t=17.81 and 3.80, P<0.01. Pulse oxygen saturation (SaO 2 ) during the operation [(91.2 ± 1.8)%]increased [(76.3 ± 8.6 )% before the

  1. Quantitation of maxillary remodeling. 1. A description of osseous changes relative to superimposition on metallic implants.

    Science.gov (United States)

    Baumrind, S; Korn, E L; Ben-Bassat, Y; West, E E

    1987-01-01

    Lateral skull radiographs for a set of 31 human subjects were examined using computer-aided methods in an attempt to quantify modal trends of maxillary remodeling during the mixed dentition and adolescent growth periods. Cumulative changes in position of anterior nasal spine (ANS), posterior nasal spine (PNS), and Point A are reported at annual intervals relative to superimposition on previously placed maxillary metallic implants. This in vivo longitudinal study confirms at a high level of confidence earlier findings by Enlow, Björk, Melsen, and others to the effect that the superior surface of the maxilla remodels downward during the period of growth and development being investigated. However, the inter-individual variability is relatively large, the mean magnitudes of change are relatively small, and the rate of change appears to diminish by 13.5 years. For the 19 subjects for whom data were available for the time interval from 8.5 to 15.5 years, mean downward remodeling at PNS was 2.50 mm with a standard deviation of 2.23 mm. At ANS, corresponding mean value was 1.56 mm with a standard deviation of 2.92 mm. Mean rotation of the ANS-PNS line relative to the implant line was 1.1 degree in the "forward" direction. However, this rotational change was particularly variable with a standard deviation of 4.6 degrees and a range of 11.3 degrees "forward" to 6.7 degrees "backward." The study provides strong evidence that the palate elongates anteroposteriorly mainly by the backward remodeling of structures located posterior to the region in which the implants were placed. There is also evidence that supports the idea of modal resorptive remodeling at ANS and PNS, but here the data are somewhat more equivocal. It appears likely, but not certain, that there are real differences in the modal patterns of remodeling between treated and untreated subjects. Because of problems associated with overfragmentation of the sample, sex differences were not investigated.

  2. Sirolimus-eluting versus bare-metal stent implantation in patients with ostial lesions

    DEFF Research Database (Denmark)

    Jørgensen, Erik; Kelbæk, Henning; Kløvgaard, Lene

    2010-01-01

    To investigate the efficacy of implantation of sirolimus-eluting stents (SES) in the ostium of coronary arteries.......To investigate the efficacy of implantation of sirolimus-eluting stents (SES) in the ostium of coronary arteries....

  3. A Randomized Seven-Year Study on Performance of the Stemmed Metal M2a-Magnum and Ceramic C2a-Taper, and the Resurfacing ReCap Hip Implants

    DEFF Research Database (Denmark)

    Borgwardt, Arne; Borgwardt, Lotte; Zerahn, Bo

    2018-01-01

    BACKGROUND: The large-diameter metal-on-metal hip prostheses were expected to have low wear and reduced dislocation rate compared to the traditional metal-on-polyethylene implants. We compare 2 such prostheses, the ReCap resurfacing implant and the M2a-Magnum stemmed implant, with the C2a ceramic......-on-ceramic stemmed implant as to clinical performance, serum concentrations of prosthesis metals, and the durability of the implants in a randomized, controlled clinical trial at 7 years of follow-up. METHODS: All included patients had osteoarthritis. Preoperatively, the size of the implants was estimated from...... of the soft tissue adjacent to the implant as well as MRI with metal artifact reduction sequence (MARS-MRI) when indicated. RESULTS: One hundred fifty-two hips in 146 patients were included. The serum cobalt and chromium concentrations were significantly higher for the 2 metal-on-metal prostheses than...

  4. Evaluation of Heat Transfer to the Implant-Bone Interface During Removal of Metal Copings Cemented onto Titanium Abutments.

    Science.gov (United States)

    Cakan, Umut; Cakan, Murat; Delilbasi, Cagri

    2016-01-01

    The aim of this investigation was to measure the temperature increase due to heat transferred to the implant-bone interface when the abutment screw channel is accessed or a metal-ceramic crown is sectioned buccally with diamond or tungsten carbide bur using an air rotor, with or without irrigation. Cobalt-chromium copings were cemented onto straight titanium abutments. The temperature changes during removal of the copings were recorded over a period of 1 minute. The sectioning of coping with diamond bur and without water irrigation generated the highest temperature change at the cervical part of the implant. Both crown removal methods resulted in an increase in temperature at the implant-bone interface. However, this temperature change did not exceed 47°C, the potentially damaging threshold for bone reported in the literature.

  5. Pulse shapes and surface effects in segmented germanium detectors

    International Nuclear Information System (INIS)

    Lenz, Daniel

    2010-01-01

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of 76 Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76 Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  6. Pulse shapes and surface effects in segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, Daniel

    2010-03-24

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  7. Effect of pressure on arsenic diffusion in germanium

    International Nuclear Information System (INIS)

    Mitha, S.; Theiss, S.D.; Aziz, M.J.; Schiferl, D.; Poker, D.B.

    1994-01-01

    We report preliminary results of a study of the activation volume for diffusion of arsenic in germanium. High-temperature high-pressure anneals were performed in a liquid argon pressure medium in a diamond anvil cell capable of reaching 5 GPa and 750 C,l which is externally heated for uniform and repeatable temperature profiles. Broadening of an ion-implanted arsenic profile was measured by Secondary Ion Mass Spectrometry. Hydrostatic pressure retards the diffusivity at 575 C, characterized by an activation volume that is +15% of the atomic volume of Ge. Implications for diffusion mechanisms are discussed

  8. False-positive 18F-fluorodeoxyglucose positron emission tomography/computed tomography in a patient with metallic implants following chondrosarcoma resection.

    Science.gov (United States)

    Zhou, P U; Tang, Jinliang; Zhang, Dong; Li, Guanghui

    2016-05-01

    Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose ( 18 F-FDG) has been used for the staging and evaluation of recurrence in cancer patients. We herein report a false-positive result of 18 F-FDG PET/computed tomography (CT) scan in a patient following chondrosarcoma resection and metallic implanting. A 35-year-old male patient with chondrosarcoma of the left iliac bone underwent radical resection, metal brace implanting and radiotherapy. A high uptake of 18 F-FDG was observed in the metallic implants and adjacent tissue during PET/CT scanning in the 5th year of follow-up. Tissue biopsy and follow-up examination identified no tumor recurrence or infection at these sites, suggesting that the results of 18 F-FDG PET/CT must be interpreted with caution in cancer patients with metallic implants.

  9. Titanium addition influences antibacterial activity of bioactive glass coatings on metallic implants.

    Science.gov (United States)

    Rodriguez, Omar; Stone, Wendy; Schemitsch, Emil H; Zalzal, Paul; Waldman, Stephen; Papini, Marcello; Towler, Mark R

    2017-10-01

    In an attempt to combat the possibility of bacterial infection and insufficient bone growth around metallic, surgical implants, bioactive glasses may be employed as coatings. In this work, silica-based and borate-based glass series were synthesized for this purpose and subsequently characterized in terms of antibacterial behavior, solubility and cytotoxicity. Borate-based glasses were found to exhibit significantly superior antibacterial properties and increased solubility compared to their silica-based counterparts, with BRT0 and BRT3 (borate-based glasses with 0 and 15 mol% of titanium dioxide incorporated, respectively) outperforming the remainder of the glasses, both borate and silicate based, in these respects. Atomic Absorption Spectroscopy confirmed the release of zinc ions (Zn 2+ ), which has been linked to the antibacterial abilities of glasses SRT0, BRT0 and BRT3, with inhibition effectively achieved at concentrations lower than 0.7 ppm. In vitro cytotoxicity studies using MC3T3-E1 osteoblasts confirmed that cell proliferation was affected by all glasses in this study, with decreased proliferation attributed to a faster release of sodium ions over calcium ions in both glass series, factor known to slow cell proliferation in vitro .

  10. Investigation of hydrogen micro-kinetics in metals with ion beam implantation and analysis

    International Nuclear Information System (INIS)

    Wang, T.S.; Peng, H.B.; Lv, H.Y.; Han, Y.C.; Grambole, D.; Herrmann, F.

    2007-01-01

    One of the most important subjects in the fusion material research is to study the hydrogen and helium concentration, diffusion and evolution in the structure material of fusion reactor, since the hydrogen and helium can be continuously produced by the large dose fast neutron irradiation on material. Various analysis Methods can be used, but the ion beam analysis method has some advantages for studying the hydrogen behaviors in nano- or micrometer resolution. In this work, the hydrogen motion and three-dimensional distribution after implantation into metal has been studied by resonance NRA, micro-ERDA and XRD etc Methods. The resolution of the H-depth-profile is in nanometer level and the lateral resolution can be reached to 2 micrometers. The evolution of hydrogen depth-profile in a titanium sample has been studied versus the change of normal stress in samples. Evident hydrogen diffusion has been observed, while a normal stress is changed in the range of 107-963 MPa. A new phase transformation during the hydrogenation is observed by the in-situ XRD analysis. The further study on the hydrogen behaviors in the structure materials of fusion reactor is in plan. (authors)

  11. Chemistry-driven structural alterations in short-term retrieved ceramic-on-metal hip implants: Evidence for in vivo incompatibility between ceramic and metal counterparts.

    Science.gov (United States)

    Zhu, Wenliang; Pezzotti, Giuseppe; Boffelli, Marco; Chotanaphuti, Thanainit; Khuangsirikul, Saradej; Sugano, Nobuhiko

    2017-08-01

    Ceramic-on-metal (CoM) hip implants were reported to experience lower wear rates in vitro as compared to metal-on-metal (MoM) bearings, thus hinting metal-ion release at lower levels in vivo. In this article, we show a spectroscopic study of two short-term retrieval cases of zirconia-toughened alumina (ZTA) femoral heads belonging to CoM hip prostheses, which instead showed poor wear performances in vivo. Metal contamination and abnormally high fractions of tetragonal-to-monoclinic (t→m) polymorphic transformation of the zirconia phase could be found on both ZTA heads, which contrasted with the optimistic predictions of in vitro experiments. At the molecular scale, incorporation of metal ions into the ceramic lattices could be recognized as due to frictionally assisted phenomena occurring at the ceramic surface. Driven by abnormal friction, diffusion of metal ions induced lattice shrinkage in the zirconia phases, while residual stress fields became stored at the surface of the femoral head. Diffusional alterations destabilized the chemistry of the ceramic surface and resulted in an abnormal increase in t→m phase transformation in vivo. Frictionally driven metal transfer to the ceramic lattice thus hinders the in vivo performance of CoM prostheses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1469-1480, 2017. © 2016 Wiley Periodicals, Inc.

  12. Controllable growth of stable germanium dioxide ultra-thin layer by means of capacitively driven radio frequency discharge

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P., E-mail: svarnas@ece.upatras.gr [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26 504, Patras (Greece); Botzakaki, M.A. [Department of Physics, University of Patras, Rion 26 504 (Greece); Skoulatakis, G.; Kennou, S.; Ladas, S. [Surface Science Laboratory, Department of Chemical Engineering, University of Patras, Rion 26 504 (Greece); Tsamis, C. [NCSR “Demokritos”, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, Aghia Paraskevi 15 310, Athens (Greece); Georga, S.N.; Krontiras, C.A. [Department of Physics, University of Patras, Rion 26 504 (Greece)

    2016-01-29

    It is well recognized that native oxide of germanium is hygroscopic and water soluble, while germanium dioxide is thermally unstable and it is converted to volatile germanium oxide at approximately 400 °C. Different techniques, implementing quite complicated plasma setups, gas mixtures and substrate heating, have been used in order to grow a stable germanium oxide. In the present work a traditional “RF diode” is used for germanium oxidation by cold plasma. Following growth, X-ray photoelectron spectroscopy demonstrates that traditional capacitively driven radio frequency discharges, using molecular oxygen as sole feedstock gas, provide the possibility of germanium dioxide layer growth in a fully reproducible and controllable manner. Post treatment ex-situ analyses on day-scale periods disclose the stability of germanium oxide at room ambient conditions, offering thus the ability to grow (ex-situ) ultra-thin high-k dielectrics on top of germanium oxide layers. Atomic force microscopy excludes any morphological modification in respect to the bare germanium surface. These results suggest a simple method for a controllable and stable germanium oxide growth, and contribute to the challenge to switch to high-k dielectrics as gate insulators for high-performance metal-oxide-semiconductor field-effect transistors and to exploit in large scale the superior properties of germanium as an alternative channel material in future technology nodes. - Highlights: • Simple one-frequency reactive ion etcher develops GeO{sub 2} thin layers controllably. • The layers remain chemically stable at ambient conditions over day-scale periods. • The layers are unaffected by the ex-situ deposition of high-k dielectrics onto them. • GeO{sub 2} oxidation and high-k deposition don't affect the Ge morphology significantly. • These conditions contribute to improved Ge-based MOS structure fabrication.

  13. Externally calibrated parallel imaging for 3D multispectral imaging near metallic implants using broadband ultrashort echo time imaging.

    Science.gov (United States)

    Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Reeder, Scott B

    2017-06-01

    To develop an externally calibrated parallel imaging technique for three-dimensional multispectral imaging (3D-MSI) in the presence of metallic implants. A fast, ultrashort echo time (UTE) calibration acquisition is proposed to enable externally calibrated parallel imaging techniques near metallic implants. The proposed calibration acquisition uses a broadband radiofrequency (RF) pulse to excite the off-resonance induced by the metallic implant, fully phase-encoded imaging to prevent in-plane distortions, and UTE to capture rapidly decaying signal. The performance of the externally calibrated parallel imaging reconstructions was assessed using phantoms and in vivo examples. Phantom and in vivo comparisons to self-calibrated parallel imaging acquisitions show that significant reductions in acquisition times can be achieved using externally calibrated parallel imaging with comparable image quality. Acquisition time reductions are particularly large for fully phase-encoded methods such as spectrally resolved fully phase-encoded three-dimensional (3D) fast spin-echo (SR-FPE), in which scan time reductions of up to 8 min were obtained. A fully phase-encoded acquisition with broadband excitation and UTE enabled externally calibrated parallel imaging for 3D-MSI, eliminating the need for repeated calibration regions at each frequency offset. Significant reductions in acquisition time can be achieved, particularly for fully phase-encoded methods like SR-FPE. Magn Reson Med 77:2303-2309, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. Weak effect of metal type and ica genes on staphylococcal infection of titanium and stainless steel implants.

    Science.gov (United States)

    Hudetz, D; Ursic Hudetz, S; Harris, L G; Luginbühl, R; Friederich, N F; Landmann, R

    2008-12-01

    Currently, ica is considered to be the major operon responsible for staphylococcal biofilm. The effect of biofilm on susceptibility to staphylococcal infection of different implant materials in vivo is unclear. The interaction of ica-positive (wild-type (WT)) and ica-negative (ica(-)) Staphylococcus aureus and Staphylococcus epidermidis strains with titanium and both smooth and rough stainless steel surfaces was studied by scanning electron microscopy in vitro and in a mouse tissue cage model during 2 weeks following perioperative or postoperative inoculation in vivo. In vitro, WT S. epidermidis adhered equally and more strongly than did WT S. aureus to all materials. Both WT strains, but not ica(-) strains, showed multilayered biofilm. In vivo, 300 CFUs of WT and ica(-)S. aureus led, in all metal cages, to an infection with a high level of planktonic CFUs and only 0.89% adherent CFUs after 8 days. In contrast, 10(6) CFUs of the WT and ica(-) strains were required for postoperative infection with S. epidermidis. In all metal types, planktonic numbers of S. epidermidis dropped to titanium cages adherent WT bacteria survived in higher numbers than ica(-) bacteria. In conclusion, the metal played a minor role in susceptibility to and persistence of staphylococcal infection; the presence of ica genes had a strong effect on biofilm in vitro and a weak effect in vivo; and S. epidermidis was more pathogenic when introduced during implantation than after implantation.

  15. Long-term outcome after drug-eluting versus bare-metal stent implantation in patients with ST-segment elevation myocardial infarction

    DEFF Research Database (Denmark)

    Holmvang, Lene; Kelbæk, Henning; Kaltoft, Anne Kjer

    2013-01-01

    This study sought to compare the long-term effects of drug-eluting stent (DES) compared with bare-metal stent (BMS) implantation in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention.......This study sought to compare the long-term effects of drug-eluting stent (DES) compared with bare-metal stent (BMS) implantation in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention....

  16. Harmonic Lattice Dynamics of Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Nelin, G

    1974-07-01

    The phonon dispersion relations of the DELTA-, LAMBDA-, and SIGMA-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field.

  17. Harmonic Lattice Dynamics of Germanium

    International Nuclear Information System (INIS)

    Nelin, G.

    1974-01-01

    The phonon dispersion relations of the Δ-, Λ-, and Σ-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field

  18. Impact of implanted metal plates on radiation dose distribution in vivo

    International Nuclear Information System (INIS)

    Liu Ming; Li Xingde; Niu Qingguo; Zhai Fushan

    2010-01-01

    Objective: To investigate the impact of metal plate on radiation dose distribution in surrounding tissues in cadaver specimens. Methods: Stainless steel plate, titanium plate, and muscle strip were implanted into the left thigh of a corpse, respectively. All the specimens were irradiated with 6 MV X-ray , SSD = 100 cm. The absorbed dose of surface was measured by thermoluminescent elements. Results: Surface dose distributions differed significantly among the three different materials (F = 57.35, P < 0.01), with the amounts of 1.18 Gy ± 0.04 Gy (stainless steel plate), 1.12 Gy ± 0.04 Gy (titanium plate) and 0.97 Gy ± 0.03 Gy (muscle strip), respectively. The surface absorbed doses on incident plane of stainless steel plate and titanium plate were significantly increased by 21.65% and 15.46% respectively as compared with that of muscle strip. The absorbed doses on the exit surface of stainless steel plate, titanium plate and muscle strip were 0.87 Gy ± 0.03 Gy, 0.90 Gy ± 0.02 Gy and 0.95 Gy ± 0.04 Gy, respectively (F =13.37, P <0.01). The doses on the exit surface of stainless steel plate and titanium plate were significantly lowered by 8.42% and 5.26% when compared with that of muscle strip. Using treatment planning system,the differences between dose distribution with and without metal plate were compared. Within 1 cm away from the incident plate, there was an obvious increase in the absorbed dose, while the influence was less than 5% 1 cm outside the surface. The effect of dose distribution on exit surface was less than 2%. Conclusions: The influence of metal plate on the radiotherapy dose distribution is significant. The deviations ranges from 5% to 29%. Under the same condition, the impact of stainless steel plate is much more than that of titanium alloy plate. (authors)

  19. Assessment of MRI issues at 3-Tesla for metallic surgical implants: findings applied to 61 additional skin closure staples and vessel ligation clips.

    Science.gov (United States)

    Gill, Amreeta; Shellock, Frank G

    2012-01-09

    Metallic skin closure staples and vessel ligation clips should be tested at 3-Tesla to characterize MRI issues in order to ensure patient safety. Therefore, metallic surgical implants were assessed at 3-Tesla for magnetic field interactions, MRI-related heating, and artifacts. A skin closure staple (Visistat Skin Stapler, staple, Polytetrafluoroethylene, PTFE, coated 316L/316LVM stainless steel; Teleflex Medical, Durham, NC) and a vessel ligation clip (Hemoclip Traditional, stainless steel; Teleflex Medical, Durham, NC) that represented the largest metallic sizes made from materials with the highest magnetic susceptibilities (i.e., based on material information) among 61 other surgical implants (52 metallic implants, 9 nonmetallic implants) underwent evaluation for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. MRI-related heating was assessed by placing each implant in a gelled-saline-filled phantom with MRI performed using a transmit/receive RF body coil at an MR system reported, whole body averaged SAR of 2.9-W/kg for 15-min. Artifacts were characterized using T1-weighted, SE and GRE pulse sequences. Each surgical implant showed minor magnetic field interactions (20- and 27-degrees, which is acceptable from a safety consideration). Heating was not substantial (highest temperature change, ≤ 1.6°C). Artifacts may create issues if the area of interest is in the same area or close to the respective surgical implant. The results demonstrated that it would be acceptable for patients with these metallic surgical implants to undergo MRI at 3-Tesla or less. Because of the materials and dimensions of the surgical implants that underwent testing, these findings pertain to 61 additional similar implants.

  20. Assessment of MRI issues at 3-Tesla for metallic surgical implants: findings applied to 61 additional skin closure staples and vessel ligation clips

    Directory of Open Access Journals (Sweden)

    Gill Amreeta

    2012-01-01

    Full Text Available Abstract Purpose Metallic skin closure staples and vessel ligation clips should be tested at 3-Tesla to characterize MRI issues in order to ensure patient safety. Therefore, metallic surgical implants were assessed at 3-Tesla for magnetic field interactions, MRI-related heating, and artifacts. Methods A skin closure staple (Visistat Skin Stapler, staple, Polytetrafluoroethylene, PTFE, coated 316L/316LVM stainless steel; Teleflex Medical, Durham, NC and a vessel ligation clip (Hemoclip Traditional, stainless steel; Teleflex Medical, Durham, NC that represented the largest metallic sizes made from materials with the highest magnetic susceptibilities (i.e., based on material information among 61 other surgical implants (52 metallic implants, 9 nonmetallic implants underwent evaluation for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. MRI-related heating was assessed by placing each implant in a gelled-saline-filled phantom with MRI performed using a transmit/receive RF body coil at an MR system reported, whole body averaged SAR of 2.9-W/kg for 15-min. Artifacts were characterized using T1-weighted, SE and GRE pulse sequences. Results Each surgical implant showed minor magnetic field interactions (20- and 27-degrees, which is acceptable from a safety consideration. Heating was not substantial (highest temperature change, ≤ 1.6°C. Artifacts may create issues if the area of interest is in the same area or close to the respective surgical implant. Conclusions The results demonstrated that it would be acceptable for patients with these metallic surgical implants to undergo MRI at 3-Tesla or less. Because of the materials and dimensions of the surgical implants that underwent testing, these findings pertain to 61 additional similar implants.

  1. Assessment of MRI issues at 3-Tesla for metallic surgical implants: findings applied to 61 additional skin closure staples and vessel ligation clips

    Science.gov (United States)

    2012-01-01

    Purpose Metallic skin closure staples and vessel ligation clips should be tested at 3-Tesla to characterize MRI issues in order to ensure patient safety. Therefore, metallic surgical implants were assessed at 3-Tesla for magnetic field interactions, MRI-related heating, and artifacts. Methods A skin closure staple (Visistat Skin Stapler, staple, Polytetrafluoroethylene, PTFE, coated 316L/316LVM stainless steel; Teleflex Medical, Durham, NC) and a vessel ligation clip (Hemoclip Traditional, stainless steel; Teleflex Medical, Durham, NC) that represented the largest metallic sizes made from materials with the highest magnetic susceptibilities (i.e., based on material information) among 61 other surgical implants (52 metallic implants, 9 nonmetallic implants) underwent evaluation for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. MRI-related heating was assessed by placing each implant in a gelled-saline-filled phantom with MRI performed using a transmit/receive RF body coil at an MR system reported, whole body averaged SAR of 2.9-W/kg for 15-min. Artifacts were characterized using T1-weighted, SE and GRE pulse sequences. Results Each surgical implant showed minor magnetic field interactions (20- and 27-degrees, which is acceptable from a safety consideration). Heating was not substantial (highest temperature change, ≤ 1.6°C). Artifacts may create issues if the area of interest is in the same area or close to the respective surgical implant. Conclusions The results demonstrated that it would be acceptable for patients with these metallic surgical implants to undergo MRI at 3-Tesla or less. Because of the materials and dimensions of the surgical implants that underwent testing, these findings pertain to 61 additional similar implants. PMID:22230200

  2. Superconductivity of tribolayers formed on germanium by friction between germanium and lead

    Energy Technology Data Exchange (ETDEWEB)

    Dukhovskoi, A.; Karapetyan, S.S.; Morozov, Y.G.; Onishchenko, A.S.; Petinov, V.I.; Ponomarev, A.N.; Silin, A.A.; Stepanov, B.M.; Tal' roze, V.L.

    1978-04-05

    A superconducting state was observed for the first time in tribolayers of germanium produced by friction of germanium with lead at 42 K. The maximum value of T/sub c/ obtained in the experiment was 19 K, which is much higher than T/sub c/ of bulk lead itself or of lead films sputtered on germanium.

  3. Pragmatic approach to the clinical work-up of patients with putative allergic disease to metallic orthopaedic implants before and after surgery.

    Science.gov (United States)

    Thyssen, J P; Menné, T; Schalock, P C; Taylor, J S; Maibach, H I

    2011-03-01

    Allergic complications following insertion of metallic orthopaedic implants include allergic dermatitis reactions but also extracutaneous complications. As metal-allergic patients and/or surgeons may ask dermatologists and allergologists for advice prior to planned orthopaedic implant surgery, and as surgeons may refer patients with complications following total joint arthroplasty for diagnostic work-up, there is a continuous need for updated guidelines. This review presents published evidence for patch testing prior to surgery and proposes tentative diagnostic criteria which clinicians can rely on in the work-up of patients with putative allergic complications following surgery. Few studies have investigated whether subjects with metal contact allergy have increased risk of developing complications following orthopaedic implant insertion. Metal allergy might in a minority increase the risk of complications caused by a delayed-type hypersensitivity reaction. At present, we do not know how to identify the subgroups of metal contact allergic patients with a potentially increased risk of complications following insertion of a metal implant. We recommend that clinicians should refrain from routine patch testing prior to surgery unless the patient has already had implant surgery with complications suspected to be allergic or has a history of clinical metal intolerance of sufficient magnitude to be of concern to the patient or a health provider. The clinical work-up of a patient suspected of having an allergic reaction to a metal implant should include patch testing and possibly in vitro testing. We propose diagnostic criteria for allergic dermatitis reactions as well as noneczematous complications caused by metal implants. © 2011 The Authors. BJD © 2011 British Association of Dermatologists.

  4. Implantable liquid metal-based flexible neural microelectrode array and its application in recovering animal locomotion functions

    Science.gov (United States)

    Guo, Rui; Liu, Jing

    2017-10-01

    With significant advantages in rapidly restoring the nerve function, electrical stimulation of nervous tissue is a crucial treatment of peripheral nerve injuries leading to common movement disorder. However, the currently available stimulating electrodes generally based on rigid conductive materials would cause a potential mechanical mismatch with soft neural tissues which thus reduces long-term effects of electrical stimulation. Here, we proposed and fabricated a flexible neural microelectrode array system based on the liquid metal GaIn alloy (75.5% Ga and 24.5% In by weight) and via printing approach. Such an alloy with a unique low melting point (10.35 °C) owns excellent electrical conductivity and high compliance, which are beneficial to serve as implantable flexible neural electrodes. The flexible neural microelectrode array embeds four liquid metal electrodes and stretchable interconnects in a PDMS membrane (500 µm in thickness) that possess a lower elastic modulus (1.055 MPa), which is similar to neural tissues with elastic moduli in the 0.1-1.5 MPa range. The electrical experiments indicate that the liquid metal interconnects could sustain over 7000 mechanical stretch cycles with resistance approximately staying at 4 Ω. Over the conceptual experiments on animal sciatic nerve electrical stimulation, the dead bullfrog implanted with flexible neural microelectrode array could even rhythmically contract and move its lower limbs under the electrical stimulations from the implant. This demonstrates a highly efficient way for quickly recovering biological nerve functions. Further, the good biocompatibility of the liquid metal material was justified via a series of biological experiments. This liquid metal modality for neural stimulation is expected to play important roles as biologic electrodes to overcome the fundamental mismatch in mechanics between biological tissues and electronic devices in the coming time.

  5. Implantable liquid metal-based flexible neural microelectrode array and its application in recovering animal locomotion functions

    International Nuclear Information System (INIS)

    Guo, Rui; Liu, Jing

    2017-01-01

    With significant advantages in rapidly restoring the nerve function, electrical stimulation of nervous tissue is a crucial treatment of peripheral nerve injuries leading to common movement disorder. However, the currently available stimulating electrodes generally based on rigid conductive materials would cause a potential mechanical mismatch with soft neural tissues which thus reduces long-term effects of electrical stimulation. Here, we proposed and fabricated a flexible neural microelectrode array system based on the liquid metal GaIn alloy (75.5% Ga and 24.5% In by weight) and via printing approach. Such an alloy with a unique low melting point (10.35 °C) owns excellent electrical conductivity and high compliance, which are beneficial to serve as implantable flexible neural electrodes. The flexible neural microelectrode array embeds four liquid metal electrodes and stretchable interconnects in a PDMS membrane (500 µ m in thickness) that possess a lower elastic modulus (1.055 MPa), which is similar to neural tissues with elastic moduli in the 0.1–1.5 MPa range. The electrical experiments indicate that the liquid metal interconnects could sustain over 7000 mechanical stretch cycles with resistance approximately staying at 4 Ω. Over the conceptual experiments on animal sciatic nerve electrical stimulation, the dead bullfrog implanted with flexible neural microelectrode array could even rhythmically contract and move its lower limbs under the electrical stimulations from the implant. This demonstrates a highly efficient way for quickly recovering biological nerve functions. Further, the good biocompatibility of the liquid metal material was justified via a series of biological experiments. This liquid metal modality for neural stimulation is expected to play important roles as biologic electrodes to overcome the fundamental mismatch in mechanics between biological tissues and electronic devices in the coming time. (paper)

  6. Vanadocene reactions with mixed acylates of silicon, germanium and tin

    International Nuclear Information System (INIS)

    Latyaeva, V.N.; Lineva, A.N.; Zimina, S.V.; Gordetsov, A.S.; Dergunov, Yu.I.

    1981-01-01

    Vanadocene interaction with di-and tri-alkyl (aryl)-derivatives of silicon, tin and germanium is studied. Dibutyltin dibenzoate under mild conditions (20 deg C, toluene) oxidates vanadocene to [CpV(OCOC 6 H 5 ) 2 ] 2 , at that, the splitting off of one Cp group in the form of cyclopentadiene and formation of the products of tin-organic fragment disproportionation (tributyltin benzoate, dibutyltin, metallic tin) take place. Tributyltin benzoate oxidates vanadocene at the mole ratio 2:1 and during prolong heating (120 deg C) in the absence of the solvent, [CpV(OCOC 6 H 5 ) 2 ] 2 and hexabutyldistannate are the products of the reaction. Acetates R 3 SnOCOCH 3 react in the similar way. The reactivity of mono- and diacylates of germanium and silicon decreases in the series of derivatives Sn>Ge>Si [ru

  7. The influence of ion implantation on the surface properties of metals and alloys

    International Nuclear Information System (INIS)

    Grant, W.A.; Carter, G.

    1975-10-01

    The report falls into three sections: (1) annealing behaviour of high dose rare gas (Ne, Ar, Kr, Xe) implantations into silicon; (2) measurement of projected and lateral range parameters for low energy heavy ions (Ar, Cu, Kr, Cd, Xe, Cs, Dy, W, Au, Pb, Bi) in silicon by Rutherford backscattering; (3) surface chemistry of ion implanted solids (e.g. corrosion, catalysis, oxidation, synthesis of compounds in ion implanted layers). (U.K.)

  8. Tungsten silicide contacts to polycrystalline silicon and silicon-germanium alloys

    International Nuclear Information System (INIS)

    Srinivasan, G.; Bain, M.F.; Bhattacharyya, S.; Baine, P.; Armstrong, B.M.; Gamble, H.S.; McNeill, D.W.

    2004-01-01

    Silicon-germanium alloy layers will be employed in the source-drain engineering of future MOS transistors. The use of this technology offers advantages in reducing series resistance and decreasing junction depth resulting in reduction in punch-through and SCE problems. The contact resistance of metal or metal silicides to the raised source-drain material is a serious issue at sub-micron dimensions and must be minimised. In this work, tungsten silicide produced by chemical vapour deposition has been investigated as a contact metallization scheme to both boron and phosphorus doped polycrystalline Si 1- x Ge x , with 0 ≤x ≤ 0.3. Cross bridge Kelvin resistor (CKBR) structures were fabricated incorporating CVD WSi 2 and polycrystalline SiGe. Tungsten silicide contacts to control polysilicon CKBR structures have been shown to be of high quality with specific contact resistance ρ c values 3 x 10 -7 ohm cm 2 and 6 x 10 -7 ohm cm 2 obtained to boron and phosphorus implanted samples respectively. The SiGe CKBR structures show that the inclusion of Ge yields a reduction in ρ c for both dopant types. The boron doped SiGe exhibits a reduction in ρ c from 3 x 10 -7 to 5 x 10 -8 ohm cm 2 as Ge fraction is increased from 0 to 0.3. The reduction in ρ c has been shown to be due to (i) the lowering of the tungsten silicide Schottky barrier height to p-type SiGe resulting from the energy band gap reduction, and (ii) increased activation of the implanted boron with increased Ge fraction. The phosphorus implanted samples show less sensitivity of ρ c to Ge fraction with a lowest value in this work of 3 x 10 -7 ohm cm 2 for a Ge fraction of 0.3. The reduction in specific contact resistance to the phosphorus implanted samples has been shown to be due to increased dopant activation alone

  9. High performance germanium MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Saraswat, Krishna [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)]. E-mail: saraswat@stanford.edu; Chui, Chi On [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Krishnamohan, Tejas [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Kim, Donghyun [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Nayfeh, Ammar [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Pethe, Abhijit [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2006-12-15

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO {sub x}N {sub y} ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin ({approx}2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices.

  10. High performance germanium MOSFETs

    International Nuclear Information System (INIS)

    Saraswat, Krishna; Chui, Chi On; Krishnamohan, Tejas; Kim, Donghyun; Nayfeh, Ammar; Pethe, Abhijit

    2006-01-01

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO x N y ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin (∼2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices

  11. The effect of metal ion implantation on the surface mechanical properties of Mylar (PET)

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, W; Sood, D K [Royal Melbourne Inst. of Tech., VIC (Australia); Yao, X; Brown, I G [California Univ., Berkeley, CA (United States). Lawrence Berkeley Lab.

    1994-12-31

    Ion implantation of polymers leads to the formation of new carbonaceous materials, the revolution during implantation of various species consists of (1) ion beam induced damage: chain scission, crosslinking, molecular emission of volatile elements and compounds, stoichiometric change in the surface layer of pristine polymers; and (2) chemical effect between ion and target materials: microalloying and precipitation. Literature regarding ion implanted polymers shows that the reorganisation of the carbon network after implantation can dramatically modify several properties of pristine polymers solubility, molecular weight, and electrical, optical and mechanical properties. However, ion implantation of polymers is actually a very complex interaction which depends on not only ion species, implantation condition, but also polymer type and specific structure. In this paper the effect of Ag or Ti ions implantation on surface mechanical properties of PET (polyethylenne terephthalate) polymer is reported. There was a clear deterioration in wear resistance after implantation of both Ag and Ti ions. It is suggested that the increment of wear after implantation may result from not only ion damage but also chemical effect between ion and target material. 3 refs., 1 tab., 2 figs.

  12. The effect of metal ion implantation on the surface mechanical properties of Mylar (PET)

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, W.; Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia); Yao, X.; Brown, I.G. [California Univ., Berkeley, CA (United States). Lawrence Berkeley Lab.

    1993-12-31

    Ion implantation of polymers leads to the formation of new carbonaceous materials, the revolution during implantation of various species consists of (1) ion beam induced damage: chain scission, crosslinking, molecular emission of volatile elements and compounds, stoichiometric change in the surface layer of pristine polymers; and (2) chemical effect between ion and target materials: microalloying and precipitation. Literature regarding ion implanted polymers shows that the reorganisation of the carbon network after implantation can dramatically modify several properties of pristine polymers solubility, molecular weight, and electrical, optical and mechanical properties. However, ion implantation of polymers is actually a very complex interaction which depends on not only ion species, implantation condition, but also polymer type and specific structure. In this paper the effect of Ag or Ti ions implantation on surface mechanical properties of PET (polyethylenne terephthalate) polymer is reported. There was a clear deterioration in wear resistance after implantation of both Ag and Ti ions. It is suggested that the increment of wear after implantation may result from not only ion damage but also chemical effect between ion and target material. 3 refs., 1 tab., 2 figs.

  13. Formation of copper silicides by high dose metal vapor vacuum arc ion implantation

    International Nuclear Information System (INIS)

    Rong Chun; Zhang Jizhong; Li Wenzhi

    2003-01-01

    Si(1 1 1) was implanted by copper ions with different doses and copper distribution in silicon matrix was obtained. The as-implanted samples were annealed at 300 and 540 deg. C, respectively. Formation of copper silicides in as-implanted and annealed samples were studied. Thermodynamics and kinetics of the reaction were found to be different from reaction at copper-silicon interface that was applied in conventional studies of copper-silicon interaction. The defects in silicon induced by implantation and formation of copper silicides were recognized by Si(2 2 2) X-ray diffraction (XRD)

  14. Immediate, non-submerged, root-analogue direct laser metal sintering (DLMS) implants: a 1-year prospective study on 15 patients.

    Science.gov (United States)

    Mangano, Francesco Guido; De Franco, Michele; Caprioglio, Alberto; Macchi, Aldo; Piattelli, Adriano; Mangano, Carlo

    2014-07-01

    This study evaluated the 1-year survival and success rate of root-analogue direct laser metal sintering (DLMS) implants, placed into the extraction sockets of 15 patients. DLMS is a technology which allows solids with complex geometry to be fabricated by annealing metal powder microparticles in a focused laser beam, according to a computer-generated three-dimensional (3D) model; the fabrication process involves the laser-induced fusion of titanium microparticles, in order to build, layer-by-layer, the desired object. Cone-beam computed tomography (CBCT) acquisition and 3D image conversion, combined with the DLMS process, allow the fabrication of custom-made, root-analogue implants (RAIs). CBCT images of 15 non-restorable premolars (eight maxilla; seven mandible) were acquired and transformed into 3D models: from these, custom-made, root-analogue DLMS implants with integral abutment were fabricated. Immediately after tooth extraction, the RAIs were placed in the sockets and restored with a single crown. One year after implant placement, clinical and radiographic parameters were assessed: success criteria included absence of pain, suppuration, and exudation; absence of implant mobility and absence of continuous peri-implant radiolucency; distance between the implant shoulder and the first visible bone-to-implant contact <1.5 mm from initial surgery; and absence of prosthetic complications. At the 1-year follow-up, no implants were lost, for a survival rate of 100 %. All implants were stable, with no signs of infection. The good conditions of the peri-implant tissues were confirmed by the radiographic examination, with a mean DIB of 0.7 mm (±0.2). The possibility of fabricating custom-made, RAI DLMS implants opens new interesting horizons for immediate placement of dental implants.

  15. The effect of authentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field.

    Science.gov (United States)

    Virtanen, H; Keshvari, J; Lappalainen, R

    2007-03-07

    As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on active implants like pacemakers have been discussed but the studies of passive metallic (i.e. conductive) implants are rare. However, some studies have shown that the EM power absorption in tissues may be enhanced due to metallic implants. In this study, the effect of authentic passive metallic implants in the head region was examined. A half-wave dipole antenna was used as an exposure source and the specific absorption rate (SAR, W kg(-1)) in the near field was studied numerically. The idea was to model the presumably worst cases of most common implants in an accurate MRI-based phantom. As exposure frequencies GSM (900 and 1800 MHz) and UMTS (2450 MHz) regions were considered. The implants studied were skull plates, fixtures, bone plates and ear rings. The results indicate that some of the implants, under very rare exposure conditions, may cause a notable enhancement in peak mass averaged SAR.

  16. Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.

    Science.gov (United States)

    Griffin, John F; Archambault, Nicholas S; Mankin, Joseph M; Wall, Corey R; Thompson, James A; Padua, Abraham; Purdy, David; Kerwin, Sharon C

    2013-11-15

    Laboratory investigation, ex vivo. Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants. Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking. Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (implantation with stainless steel implants. N/A.

  17. Metallic and/or oxygen ion implantation into AlN ceramics as a method of preparation for its direct bonding with copper

    International Nuclear Information System (INIS)

    Barlak, M.; Borkowska, K.; Olesinska, W.; Kalinski, D.; Piekoszewski, J.; Werner, Z.; Jagielski, J.; Sartowska, B.

    2006-01-01

    Direct bonding (DB) process is recently getting an increasing interest as a method for producing high quality joints between aluminum nitride (AlN) ceramics and copper. The metallic ions were implanted using an MEVVA type TITAN implanter with unseparated beam. Oxygen ions were implanted using a semi-industrial ion implanter without mass separation equipped with a gaseous ion source. The substrate temperature did not exceed 200 o C. Ions were implanted at two acceleration voltages, i.e. 15 and 70 kV. The fluence range was between 1·E16 and 1·E18 cm -2 . After implantation, some of the samples were characterized by the Rutherford backscattering (RBS) method. In conclusion: (a) The investigations performed in the present work confirm an assumption that ion implantation is a very promising technique as a pretreatment of AlN ceramics for the formation of the joints with copper in direct bonding process. (b) It has been shown that titanium implantation gives the best results in comparison to other metals examined (Fe, Cr, Cu) but also in comparison to double Ti+O and O+Ti implantations

  18. Promising Ta-Ti-Zr-Si metallic glass coating without cytotoxic elements for bio-implant applications

    Science.gov (United States)

    Lai, J. J.; Lin, Y. S.; Chang, C. H.; Wei, T. Y.; Huang, J. C.; Liao, Z. X.; Lin, C. H.; Chen, C. H.

    2018-01-01

    Tantalum (Ta) is considered as one of the most promising metal due to its high corrosion resistance, excellent biocompatibility and cell adhesion/in-growth capabilities. Although there are some researches exploring the biomedical aspects of Ta and Ta based alloys, systematic characterizations of newly developed Ta-based metallic glasses in bio-implant applications is still lacking. This study employs sputtering approach to produced thin-film Ti-based metallic glasses due to the high melting temperature of Ta (3020 °C). Two fully amorphous Ta-based metallic glasses composed of Ta57Ti17Zr15Si11 and Ta75Ti10Zr8Si7 are produced and experimentally characterized in terms of their mechanical properties, bio-corrosion properties, surface hydrophilic characteristics, and in-vitro cell viability and cells attachment tests. Compare to conventional pure Ti and Ta metals, the developed Ta-based metallic glasses exhibit higher hardness and lower modulus which are better match to the mechanical properties of bone. MTS assay results show that Ta-based metallic glasses show comparable cell viability and cell attachment rate compared to that of pure Ti and Ta surface in a 72 h in-vitro test.

  19. Toward Patient Specific Long Lasting Metallic Implants for Mandibular Segmental Defects

    Science.gov (United States)

    Shayesteh Moghaddam, Narges

    Mandibular defects may result from tumor resection, trauma, or inflammation. The goals of mandibular reconstruction surgeries are to restore mandible function and aesthetics. To this end, surgeons use a combination of bone grafts and metallic implants. These implants have drastically different mechanical properties than the surrounding bone. As a result, the stress distribution in the mandible changes after surgery. The long-term abnormal stress/strain distribution may lead to either graft failure due to bone resorption as a result of stress shielding, or hardware failure due to stress concentrations. During the healing period of six to nine months it is important that complete immobilization, bringing mandibular micro-motion down to the level of 200-500 mum during chewing, is achieved. After this period it is desired that bone undergo normal stress for long-term success of the treatment. Although current high stiffness fixation hardware accomplishes this immobilization during the healing period, the hardware continues to alter the normal stress-strain trajectory seen during chewing once the engrafted bone heals. Over the long-term, the immobilized and stress-shielded engrafted bone tends to resorb. On the other hand, hardware fracturing or/and screw loosening is observed as the stress is concentrated at certain locations on the hardware. Equally as important is the permanent loss of chewing power due to the altered stress-strain relationships. The first stage of this research is to study the problems encountered following a mandibular segmental defect reconstructive surgery. To this end, we constructed a finite element model of a healthy mandible, which includes cortical and cancellous bone, teeth (enamel and dentin components), and the periodontal ligament. Using this model, we studied a healthy adult mandible under maximum molar bite force for stress, strain, displacement, and reaction force distribution. For mandibular segmental defect reconstruction the

  20. In vitro assessment of tissue heating near metallic medical implants by exposure to pulsed radio frequency diathermy

    Energy Technology Data Exchange (ETDEWEB)

    Ruggera, P S; Witters, D M; Maltzahn, G von; Bassen, H I [Center for Devices and Radiological Health, Food and Drug Administration, HFZ-133, 9200 Corporate Blvd., Rockville, MD 20850 (United States)

    2003-09-07

    A patient with bilateral implanted neurostimulators suffered significant brain tissue damage, and subsequently died, following diathermy treatment to hasten recovery from teeth extraction. Subsequent MRI examinations showed acute deterioration of the tissue near the deep brain stimulator (DBS) lead's electrodes which was attributed to excessive tissue heating induced by the diathermy treatment. Though not published in the open literature, a second incident was reported for a patient with implanted neurostimulators for the treatment of Parkinson's disease. During a diathermy treatment for severe kyphosis, the patient had a sudden change in mental status and neurological deficits. The diathermy was implicated in causing damage to the patient's brain tissue. To investigate if diathermy induced excessive heating was possible with other types of implantable lead systems, or metallic implants in general, we conducted a series of in vitro laboratory tests. We obtained a diathermy unit and also assembled a controllable laboratory exposure system. Specific absorption rate (SAR) measurements were performed using fibre optic thermometry in proximity to the implants to determine the rate of temperature rise using typical diathermy treatment power levels. Comparisons were made of the SAR measurements for a spinal cord stimulator (SCS) lead, a pacemaker lead and three types of bone prosthesis (screws, rods and a plate). Findings indicate that temperature changes of 2.54 and 4.88 deg. C s{sup -1} with corresponding SAR values of 9129 and 17 563 W kg{sup -1} near the SCS and pacemaker electrodes are significantly higher than those found in the proximity of the other metallic implants which ranged from 0.04 to 0.69 deg C s{sup -1} (129 to 2471 W kg{sup -1}). Since the DBS leads that were implanted in the reported human incidents have one-half the electrode surface area of the tested SCS lead, these results imply that tissue heating at rates at least equal to or up to

  1. SU-E-T-492: The Dosimetric and Clinical Impact of the Metallic Dental Implants on Radiation Dose Distributions in IMRT Head and Neck Cancer Patients.

    Science.gov (United States)

    Wang, L; Xing, L; Le, Q

    2012-06-01

    In H&N cancer patients, the development of oral mucositis is related closely to the radiation dose to the oral cavity. It is generally presumed that the existence of metallic dental implants makes it worse due to the scattering effect of the metal. This study investigates the effects of the dental implants on radiation doses to PTV, tongue mucosa, and other structures for IMRT H&N cancer patients by Monte Carlo (MC) dose calculations. Two H&N cancer patients who have dental implant and are treated by IMRT technique are selected for the purpose. The BEAMnrc/DOSXYZnrc MC codes are employed for the CT-image based dose calculations. The radiation sources are the validated Varian phase-space files for 6MV linac beams. The CT image artifacts caused by the dental fillings are replaced by tissue material. Two sets of MC calculations for each patient are performed at a calculation statistics of 1%: one treats all dental implants as bones, the other substitutes the implants by metal of either titanium or gold with correct density. Doses in PTV and various tissue structures are compared for the two scenarios. With titanium implant, there is no significant difference in doses to PTV and tongue mucosa from that when treating implant as bone. With gold implant, the mean dose to PTV is slightly lowered by 1%; the mean dose to tongue mucosa is reduced by less than 0.5%, although the maximum dose is increased by 5%. The scattering dose from titanium implants is not of concern for H&N patients irradiated by 6MV IMRT beams. For gold implants, the scattering dose to tongue mucosa is not as severe as presumed; and the dose to PTV could be slightly compromised due to the attenuation effect of the metal. This work was supported in part by Varian Medical Systems. © 2012 American Association of Physicists in Medicine.

  2. Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants.

    Science.gov (United States)

    Pradhan, D; Wren, A W; Misture, S T; Mellott, N P

    2016-01-01

    Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb2O5) and titanium (TiO2) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb2O5 at 75 °C with 40% weight loss below 400 °C, and minimal weight loss between 400 and 850 °C. Regarding TiO2 an endotherm was present at 92 °C with 25% weight loss below 400 °C, and 4% between 400 and 850 °C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb2O5 (450 °C), hexagonal-Nb2O5 (525 °C), orthorhombic-Nb2O5 (650 °C), amorphous-TiO2 (275 °C) and tetragonal TiO2 (500 °C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1, 7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb2O5 (525 °C) and TiO2 (500 °C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO2 (122%) samples when compared to the growing cell population while Nb2O5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Comparison of Fatigue Properties and Fatigue Crack Growth Rates of Various Implantable Metals

    Science.gov (United States)

    Okazaki, Yoshimitsu

    2012-01-01

    The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion resistance and biocompatibility. The highly biocompatible Ti-15Zr-4Nb-4Ta alloy exhibited an excellent balance between strength and ductility. Its notched tensile strength was much higher than that of a smooth specimen. The strength of 20% cold-worked commercially pure (C.P.) grade 4 Ti was close to that of Ti alloy. The tension-to-tension fatigue strength of an annealed Ti-15Zr-4Nb-4Ta rod at 107 cycles was approximately 740 MPa. The fatigue strength of this alloy was much improved by aging treatment after solution treatment. The fatigue strengths of C.P. grade 4 Ti and stainless steel were markedly improved by 20% cold working. The fatigue strength of Co-Cr-Mo alloy was markedly increased by hot forging. The notch fatigue strengths of 20% cold-worked C.P. grade 4 Ti, and annealed and aged Ti-15Zr-4Nb-4Ta, and annealed Ti-6Al-4V alloys were less than those of the smooth specimens. The fatigue crack growth rate of Ti-15Zr-4Nb-4Ta was the same as that of Ti-6Al-4V. The fatigue crack growth rate in 0.9% NaCl was the same as that in air. Stainless steel and Co-Cr-Mo-Ni-Fe alloy had a larger stress-intensity factor range (ΔK) than Ti alloy.

  4. Formation of metal-alloy nanoclusters in silica by ion implantation and annealing in selected atmosphere

    International Nuclear Information System (INIS)

    Battaglin, G.; Cattaruzza, E.; Gonella, F.; Mattei, G.; Mazzoldi, P.; Sada, C.; Zhang, X.

    2000-01-01

    The formation of binary alloy clusters in sequentially ion-implanted Au-Cu or Au-Ag silica glass has been studied as a function of the annealing atmosphere. Alloy formation has been evidenced in the as-implanted samples. The selective influence on Au precipitation of either oxygen or hydrogen annealing atmosphere governs the alloy cluster formation and the thermal stability

  5. Wear behaviour of the couple polyethylene Ti6Al4V: Effects of the metallic surface preparation and nitrogen implantation

    Science.gov (United States)

    Martinella, R.; Giovanardi, S.; Palombarini, G.; Corchia, M.; Delogu, P.; Giorgi, R.; Tosello, C.

    The wear behaviour improvement of the tribological couple Ti6Al4V-UHMWPE is of great interest to the medical field. Wear tests were carried out in water on a reciprocating UHMWPE annulus on implanted Ti6Al4V disc tribotestcr, with loads and velocities simulating those of hip joints. A comparison of wear behaviours was also carried out between untreated Ti6Al4V samples and Ti6Al4V subjected to a special lapping procedure. UHMWPE worn against ion-implanted and especially lapped Ti alloy showed the lowest wear rate, while, the highest (about one order of magnitude) was shown by the UHMWPE against untreated Ti6Al4V samples. XPS and AES surface analyses were carried out on metallic discs to examine the chemical composition of the surface before wear tests. Moreover depth distribution of nitrogen in implanted samples was determined using the same techniques. SEM observations displayed a polyethylene transfer film on all metallic surfaces, particularly on untreated Ti6Al4V samples. A discussion about uselessness of more conventional surface treatments for the Ti alloy is also reported.

  6. Analyzer-based imaging technique in tomography of cartilage and metal implants: A study at the ESRF

    International Nuclear Information System (INIS)

    Coan, Paola; Mollenhauer, Juergen; Wagner, Andreas; Muehleman, Carol; Bravin, Alberto

    2008-01-01

    Monitoring the progression of osteoarthritis (OA) and the effects of therapy during clinical trials is still a challenge for present clinical imaging techniques since they present intrinsic limitations and can be sensitive only in case of advanced OA stages. In very severe cases, partial or complete joint replacement surgery is the only solution for reducing pain and restoring the joint functions. Poor imaging quality in practically all medical imaging technologies with respect to joint surfaces and to metal implant imaging calls for the development of new techniques that are sensitive to stages preceding the point of irreversible damage of the cartilage tissue. In this scenario, X-ray phase contrast modalities could play an important role since they can provide improved contrast compared to conventional absorption radiography, with a similar or even reduced tissue radiation dose. In this study, the analyzer-based imaging (ABI), a technique sensitive to the X-ray refraction and permitting a high scatter rejection, has been successfully applied in vitro on excised human synovial joints and sheep implants. Pathological and healthy joints as well as metal implants have been imaged in projection and computed tomography ABI mode at high resolution and clinically compatible doses (<10 mGy). Volume rendering and segmentation permitted visualization of the cartilage from volumetric CT-scans. The results demonstrate that ABI can provide an unequivocal non-invasive diagnosis of the state of disease of the joint and be considered a new tool in orthopaedic research

  7. Implantation of titanium, chromium, yttrium, molybdenum, silver, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum ion source into 440C stainless steel

    International Nuclear Information System (INIS)

    Sasaki, Jun; Hayashi, Kazunori; Sugiyama, Kenji; Ichiko, Osami; Hashiguchi, Yoshihiro

    1992-01-01

    Titanium, yttrium, molybdenum, silver, chromium, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum arc (MEVVA) ion source were implanted into 440C stainless steel in the dose region 10 17 ions cm -2 with extraction voltages of up to 70 kV. Glow discharge spectroscopy (GDS), friction coefficient, and Vickers microhardness of the specimens were studied. Grooves made by friction tests were investigated by electron probe microanalysis (EPMA). GDS showed incorporation of carbon in the yttrium, hafnium, tantalum, tungsten and platinum implanted specimens, as well as titanium implanted samples. A large amount of oxygen was observed in the yttrium implanted specimen. The friction coefficient was measured by reciprocating sliding of an unimplanted 440C ball without lubricant at a load of 0.245 N. The friction decreased and achieved a stable state after implantation of titanium, hafnium and tantalum. The friction coefficient of the platinum implanted specimen showed a gradual decrease after several cycles of sliding at high friction coefficient. The yttrium implanted sample exhibited a decreased but slightly unstable friction coefficient. Results from EPMA showed that the implanted elements, which gave decreased friction, remained even after sliding of 200 cycles. Implantation of chromium, molybdenum, silver and tungsten did not provide a decrease in friction and the implants were gone from the wear grooves after the sliding tests. (orig.)

  8. The influence of direct laser metal sintering implants on the early stages of osseointegration in diabetic mini-pigs

    Directory of Open Access Journals (Sweden)

    Tan NW

    2017-07-01

    Full Text Available Naiwen Tan,1–3,* Xiangwei Liu,1,2,* Yanhui Cai,4 Sijia Zhang,1,2 Bo Jian,1,2 Yuchao Zhou,1,2 Xiaoru Xu,1,2 Shuai Ren,1,2 Hongbo Wei,1,2 Yingliang Song1,2 1State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Xi’an, Shaanxi, China; 2Department of Implant Dentistry, School of Stomatology, The Fourth Military Medical University, Xi’an, Shaanxi, China; 3Department of Stomatology, Hospital 463 of PLA, Xi’an, Shaanxi, China; 4Department of Anesthesiology, Xijing Hospital, The Fourth Military Medical University, Xi’an, Shaanxi, China *These authors contributed equally to this work Background: High failure rates of oral implants have been reported in diabetic patients due to the disruption of osseointegration. The aim of this study was to investigate whether direct laser metal sintering (DLMS could improve osseointegration in diabetic animal models. Methods: Surface characterizations were carried out on two types of implants. Cell morphology and the osteogenic-related gene expression of MG63 cells were observed under conditions of DLMS and microarc oxidation (MAO. A diabetes model in mini-pigs was established by intravenous injection of streptozotocin (150 mg/kg, and a total of 36 implants were inserted into the mandibular region. Micro-computed tomography (micro-CT and histologic evaluations were performed 3 and 6 months after implantation. Results: The Ra (the average of the absolute height of all points of MAO surface was 2.3±0.3 µm while the DLMS surface showed the Ra of 27.4±1.1 µm. The cells on DLMS implants spread out more podia than those on MAO implants through cell morphology analysis. Osteogenic-related gene expression was also dramatically increased in the DLMS group. Obvious improvement was observed in the micro-CT and Van Gieson staining analyses of DLMS implants compared with MAO at 3 months

  9. The effect of ion implantation on the fatigue behavior of metals and alloys

    International Nuclear Information System (INIS)

    Chakrabortty, S.B.; Kujore, A.; Legg, K.O.; Starke, E.A.

    1981-01-01

    The effect of ion implantation on the strain and stress controlled fatigue behavior of polycrystalline copper has been investigated. The cyclic stress-strain response, strain-life and stress-life relationships and fatigue crack nucleation behavior have been studied. The results from the non-implanted materials have been compared with those from the implanted materials. Four implant species, one with a positive misfit, one with a negative misfit, one with a zero misfit, and one insoluble under equilibrium conditions have been used. Most of the fatigue tests were performed in laboratory air. Ion implantation changes the surface deformation behavior for both monotonic and cyclic loading with a corresponding change in hardening rate. Larger changes are observed for the cyclic loading. Implantations which lead to a more homogeneous deformation (fine slip) near the surface, improves the resistance to fatigue crack initiation. Surface compressive residual stresses, induced from implanting a positive misfit species, have a major influence on crack initiation in the stress-life regime

  10. Modifications of the hydriding kinetics of a metallic surface, using ion implantation

    International Nuclear Information System (INIS)

    Crusset, D.

    1992-10-01

    Uranium reacts with hydrogen to form an hydride: this reaction leads to the total destruction of the material. To modify the reactivity of an uranium surface towards hydrogen, ion implantation was selected, among surface treatments techniques. Four elements (carbon, nitrogen, oxygen, sulfur) were implanted to different doses. The results show a modification of the hydriding mechanism and a significant increase in the reaction induction times, notably at high implantation doses. Several techniques (SIMS, X-rays phases analysis and residual stresses determination) were used to characterize the samples and understand the different mechanisms involved

  11. Randomized clinical trial of implant-supported ceramic-ceramic and metal-ceramic fixed dental prostheses: preliminary results.

    Science.gov (United States)

    Esquivel-Upshaw, Josephine F; Clark, Arthur E; Shuster, Jonathan J; Anusavice, Kenneth J

    2014-02-01

    The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52-75 years) were recruited for the study to receive a three-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD, and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher's exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure (p = 0.68), and connector height (p = 0

  12. Effects of noble-metal ion implantation on corrosion inhibition and charge injection capability of surgical Ti and Ti-6Al-4V

    International Nuclear Information System (INIS)

    Lee, I.S.

    1989-01-01

    Studies are described involving effects of noble-metal ion implantation on corrosion inhibition and charge injection capabilities of surgical Ti and Ti-6Al-4V. With surgical alloys, harmful biological responses are principally due to the type and quantity of metal ions released by the corrosion process. One approach to improve long-term biological performance involves surface modifications to significantly reduce degradation rates. With regard to surface-modifications, one of the most effective methods is through ion implantation. Results are presented for ion-implanted Au, Rh, and Ir. For the static in vitro corrosion properties, the noble-metal ion implanted Ti-6Al-4V and commercially-pure (CP) Ti were investigated in non-passivating acid and passivating saline solutions. It was postulated that during the early stages of corrosion (or during a corrosion pretreatment) the implanted noble-metal would enrich at the surface and significantly reduce subsequent corrosion rates. The observed behavior for the Ir and Rh implanted materials appeared to follow the postulated mechanism, with both initial and time-dependent improvements in corrosion resistance. However, the Au implanted material yielded early benefits, but the enhanced corrosion resistance deteriorated with time. X-ray photoelectron spectroscopy (XPS) analysis indicated that the implanted Au atoms remained as pure metallic Au, while the Ir and Rh atoms were in some oxide state, which gave the good adhesion of the Ir or Rh enriched surface to the Ti substrate. For a stimulating neural electrode, the charge density should be as large as possible to provide adequate stimulation of the nervous system while allowing for miniaturization of the electrode. Activated Ir has been known as having the highest charge injection capability of any material known

  13. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G.; Chathuranga Senarathna, K.G. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Herath, H.M.T.U. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Premachandra, T.N. [Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Ranasinghe, C.S.K. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.P.V.J. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.M.G., E-mail: rmgr@pdn.ac.lk [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Edirisinghe, Mohan; Mahalingam, S. [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Bandara, I.M.C.C.D. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia); Singh, Sanjleena [Central Analytical Research Facility, Institute of Future Environments, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia)

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO{sub 2} thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. - Highlights: • Colloidal hydroxyapatite nanorods are prepared by a novel method. • Surfaces of titanium metal plates are modified by self-forming TiO{sub 2} thin-films. • Prostheses are prepared by coating hydroxyapatite on surface modified Ti metal. • Bioactivity and noncytotoxicity are increased with surface modifications.

  14. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

    International Nuclear Information System (INIS)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G.; Chathuranga Senarathna, K.G.; Herath, H.M.T.U.; Premachandra, T.N.; Ranasinghe, C.S.K.; Rajapakse, R.P.V.J.; Rajapakse, R.M.G.; Edirisinghe, Mohan; Mahalingam, S.; Bandara, I.M.C.C.D.; Singh, Sanjleena

    2016-01-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO_2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. - Highlights: • Colloidal hydroxyapatite nanorods are prepared by a novel method. • Surfaces of titanium metal plates are modified by self-forming TiO_2 thin-films. • Prostheses are prepared by coating hydroxyapatite on surface modified Ti metal. • Bioactivity and noncytotoxicity are increased with surface modifications.

  15. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO -- a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Arenholz, Elke; Zhou, S.; Potzger, K.; Talut, G.; Reuther, H.; Kuepper, K.; Grenzer, J.; Xu, Q.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.

    2008-01-01

    We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  16. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO: a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Zhou Shengqiang; Potzger, K; Talut, G; Reuther, H; Kuepper, K; Grenzer, J; Xu Qingyu; Muecklich, A; Helm, M; Fassbender, J; Arenholz, E

    2008-01-01

    We investigated ZnO(0 0 0 1) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  17. Successful treatment of coronary artery pseudoaneurysm by graft stent, which developed after the implantation of bare metal stent

    Directory of Open Access Journals (Sweden)

    Utku Şenol

    2013-03-01

    Full Text Available Although coronary artery pseudoaneurysm which couldoccur following percutaneous coronary interventions is arare complication, it can be mortal. As soon as the pseudoaneurysmis diagnosed, it should be treated by percutaneousintervention or surgery. Graft stent implantationis a preferred treatment for appropriate patients. In thiscase report, we presented a successful treatment of coronaryartery pseudoaneurysm by graft stent; which developedafter the implantation of bare metal stent into theleft anterior descending coronary artery. J Clin Exp Invest2013; 4 (1: 126-129Key words: Coronary artery, pseudoaneurysm, graft stent

  18. Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, D.; Wren, A.W.; Misture, S.T.; Mellott, N.P., E-mail: mellott@alfred.edu

    2016-01-01

    Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb{sub 2}O{sub 5}) and titanium (TiO{sub 2}) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb{sub 2}O{sub 5} at 75 °C with 40% weight loss below 400 °C, and minimal weight loss between 400 and 850 °C. Regarding TiO{sub 2} an endotherm was present at 92 °C with 25% weight loss below 400 °C, and 4% between 400 and 850 °C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb{sub 2}O{sub 5} (450 °C), hexagonal-Nb{sub 2}O{sub 5} (525 °C), orthorhombic-Nb{sub 2}O{sub 5} (650 °C), amorphous-TiO{sub 2} (275 °C) and tetragonal TiO{sub 2} (500 °C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1, 7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb{sub 2}O{sub 5} (525 °C) and TiO{sub 2} (500 °C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO{sub 2} (122%) samples when compared to the growing cell population while Nb{sub 2}O{sub 5} samples exhibited a range of viability (64–105%), partially dependent on materials atomic structure. - Highlights: • Niobium and titanium oxides were prepared to determine the effect of structure on bioactivity. • Simulated body fluid testing resulted in positive surface chemical and morphological changes. • Amorphous, rod-like CaP deposits were observed on the surfaces. • Niobium oxide exhibited a range of viability partially dependent on materials atomic structure.

  19. Effects of trap-assisted tunneling on gate-induced drain leakage in silicon-germanium channel p-type FET for scaled supply voltages

    Science.gov (United States)

    Tiwari, Vishal A.; Divakaruni, Rama; Hook, Terence B.; Nair, Deleep R.

    2016-04-01

    Silicon-germanium is considered as an alternative channel material to silicon p-type FET (pFET) for the development of energy efficient high performance transistors for 28 nm and beyond in a high-k metal gate technology because of its lower threshold voltage and higher mobility. However, gate-induced drain leakage (GIDL) is a concern for high threshold voltage device design because of tunneling at reduced bandgap. In this work, the trap-assisted tunneling and band-to-band tunneling (BTBT) effects on GIDL is analyzed and modeled for SiGe pFETs. Experimental results and Monte Carlo simulation results reveal that the pre-halo germanium pre-amorphization implant used to contain the short channel effects contribute to GIDL at the drain sidewall in addition to GIDL due to BTBT in SiGe devices. The results are validated by comparing the experimental observations with the numerical simulation and a set of calibrated models are used to describe the GIDL mechanisms for various drain and gate bias.

  20. Synthesis and evaluation of germanium organometallic compounds as precursors for chemical vapor deposition (CVD) and for obtaining nanoparticles of elemental germanium

    International Nuclear Information System (INIS)

    Ballestero Martinez, Ernesto

    2014-01-01

    The interest in the development of materials having applications such as electronics areas or biomarkers has affected the synthesis of new compounds based on germanium. This element has had two common oxidation states, +4 and +2, of them, +2 oxidation state has been the least studied and more reactive. Additionally, compounds of germanium (II) have had similarities with carbenes regarding the chemical acid-base Lewis. The preparation of compounds of germanium (II) with ligands β-decimations has enabled stabilization of new chemical functionalities and, simultaneously, provided interesting thermal properties to develop new preparation methodologies of materials with novel properties. The preparation of amides germanium(II) L'Ge(NHPh) [1, L' = {HC (CMeN-2,4,6-Me 3 C 6 H 2 ) 2 }], L'Ge(4-NHPy) [2] L'Ge(2-NHPy) [3] and LGe(2-NHPy) [4, L = {HC(CMeN-2,6- i Pr 2 C 6 H 3 ) 2 }]; the structural chemical composition were determined using techniques such as nuclear magnetic resonance ( 1 H, 13 C), other techniques are treated: elemental analysis, melting point, infrared spectroscopy, X-ray diffraction of single crystal and thermal gravimetric analysis (TGA). The TGA has showed that 4-1 have experimented a thermal decomposition; therefore, these compounds could be considered as potential starting materials for obtaining germanium nitride (GeN x ). Certainly, the availability of nitrogen coordinating atoms in the chemical composition in 2-4 have been interesting because it could act as ligands in reactions with transition metal complexes. That way, information could be obtained at the molecular level for some reactions and interactions that in surface chemistry have used similar link sites, for example, chemical functionalization of silicon and germanium substrates. The synthesis and structural characterization of germanium chloride compound(II) L''GeCl [5, L'' = HC{(CMe) (N-2,6-Me 2 C 6 H 3 )} 2 ], which could be used later for the

  1. Cell-laden hydrogel/titanium microhybrids: Site-specific cell delivery to metallic implants for improved integration.

    Science.gov (United States)

    Koenig, Geraldine; Ozcelik, Hayriye; Haesler, Lisa; Cihova, Martina; Ciftci, Sait; Dupret-Bories, Agnes; Debry, Christian; Stelzle, Martin; Lavalle, Philippe; Vrana, Nihal Engin

    2016-03-01

    the titanium beads and fibroblast proliferation was significantly higher in hybrids compared to gel only controls. The MMP (Matrix Metalloproteinase)-sensitive hydrogels induced sprouting by cells in co-culture configuration which was quantified by fluorescence microscopy, confocal microscopy and qRT-PCR (Quantitative Reverse transcription polymerase chain reaction). When the microhybrid up-scaled to 3D thick structures, cellular localisation in specific areas of the 3D titanium structures was achieved, without decreasing overall cell proliferation compared to titanium only scaffolds. Microhybrids of titanium and hydrogels are useful models for deciding the necessary modifications of metallic implants and they can be used as a modelling system for the study of tissue/titanium implant interactions. This article demonstrates a method to apply cell-laden hydrogels to porous titanium implants and a model of titanium/hydrogel interaction at micro-level using titanium microbeads. The feasibility of site-specific modification of titanium implants with cell-laden microgels has been demonstrated. Use of titanium microbeads in combination with hydrogels with conventional analysis techniques as described in the article can facilitate the characterisation of surface modification of titanium in a relevant model system. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  2. Immediate loading of mandibular overdentures supported by one-piece, direct metal laser sintering mini-implants: a short-term prospective clinical study.

    Science.gov (United States)

    Mangano, Francesco G; Caprioglio, Alberto; Levrini, Luca; Farronato, Davide; Zecca, Piero A; Mangano, Carlo

    2015-02-01

    Only a few studies have dealt with immediately loaded, unsplinted mini-implants supporting ball attachment-retained mandibular overdentures (ODs). The aim of this study is to evaluate treatment outcomes of ball attachment-retained mandibular ODs supported by one-piece, unsplinted, immediately loaded, direct metal laser sintering (DMLS) mini-implants. Over a 4-year period (2009 to 2012), all patients referred to the Dental Clinic, University of Varese, and to a private practice for treatment with mandibular ODs were considered for inclusion in this study. Each patient received three or four DMLS mini-implants. Immediately after implant placement, a mandibular OD was connected to the implants. At each annual follow-up session, clinical and radiographic parameters were assessed, including the following outcome measures: 1) implant failures; 2) peri-implant marginal bone loss; and 3) complications. Statistical analysis was conducted using a life-table analysis. A total of 231 one-piece DMLS mini-implants were inserted in 62 patients. After 4 years of loading, six implants failed, giving an overall cumulative survival rate of 96.9%. The mean distance between the implant shoulder and the first visible bone-to-implant contact was 0.38 ± 0.25 and 0.62 ± 0.20 mm at the 1- and 4-year follow-up examinations, respectively. An incidence of 6.0% of biologic complications was reported; prosthetic complications were more frequent (12.9%). Within the limits of this study, it can be concluded that the immediate loading of one-piece, unsplinted, DMLS titanium mini-implants by means of ball attachment-supported mandibular ODs is a successful treatment procedure. Long-term follow-up studies are needed to confirm these results.

  3. Electrical enhancement of direct methanol fuel cells by metal-plasma ion implantation Pt-Ru/C multilayer catalysts.

    Science.gov (United States)

    Weng, Ko-Wei; Chen, Yung-Lin; Chen, Ya-Chi; Lin, Tai-Nan

    2009-02-01

    Direct methanol fuel cells (DMFC) have been widely studied owing to their simple cell configuration, high volume energy density, short start-up time, high operational reliability and other favorable characteristics. However, major limitations include high production cost, poisoning of the catalyst and methanol crossover. This study adopts a simple technique for preparing Pt-Ru/C multilayer catalysts, including magnetron sputtering (MS) and metal-plasma ion implantation (MPII). The Pt catalysts were sputtered onto the gas diffusion layer (GDL), followed by the implantation of Ru catalysts using MPII (at an accelerating voltage of 20 kV and an implantation dose of 1 x 10(16) ions/cm2). Pt-Ru is repeatedly processed to prepare Pt-Ru/C multilayer catalysts. The catalyst film structure and microstructure were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM), respectively. The cell performance was tested using a potential stat/galvano-stat. The results reveal that the membrane electrode assembly (MEA) of four multilayer structures enhances the cell performance of DMFC. The measured power density is 2.2 mW/cm2 at a methanol concentration of 2 M, with an OCV of 0.493 V.

  4. Study of helium diffusion, implanted at a cyclotron, in face-centered cubic metals: Au, Ag and Al

    International Nuclear Information System (INIS)

    Sciani, V.

    1985-01-01

    Helium in metals is produced by nuclear reactions of energetic particles. In nuclear technology the interest on helium in metals is import, due to its production by (n, α) reaction. Because helium has extremely low solubility in metals, the precipitation in the form of filled bubbles at elevated temperatures occurs, which have detrimental effects on mechanical properties and may limit the lifetime of structural components. One typical example is the high temperature embrittlement. The nucleation and growth of the bubbles strongly depends on the mobility of the helium. This work presents the study of helium diffusion in Au, Ag and Al at temperatures above room temperature. The helium created by (n, α) reactions has been simulated by homogeneous alpha particles implantation in cyclotron, at room temperature, in specimens of thicknesses between 5 and 50 μm and helium concentration between 10 -3 to 10 ppm. After implantation, the specimens were dropped in a furnace in a UHV-chamber and the diffusion was measured by observing the He-release during linear and isothermal annealings. The occurence of free diffusion was comparing the dependence of release kinetics on helium concentration, sample thickness, time and heating rate to diffusion theory and is clearly separeted from agglomeration process. The diffusion constants of helium in Au, Ag and Al follow an Arrhenius behavior, with: Au:D o =10 -1.0 cm 2 /s ΔH=1.70eV Ag:D 0 =10 -1.2 cm 2 /s ΔH=1.51eV Al:D o =10 +0.5 cm 2 /s ΔH=1.40eV. The results are compared to self-diffusion and to the diffusion of other gases in these metals. Comparison with theoretical estimates favours the vacancy mechanism for helium diffusion in Au, Ag and Al. (author) [pt

  5. Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

    Energy Technology Data Exchange (ETDEWEB)

    Deligianni, X. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology; Bieri, O. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Elke, R. [Orthomerian, Basel (Switzerland); Wischer, T.; Egelhof, T. [Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology

    2015-12-15

    Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm{sup 3} ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

  6. Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

    International Nuclear Information System (INIS)

    Deligianni, X.; Wischer, T.; Egelhof, T.

    2015-01-01

    Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm 3 ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

  7. Theoretical Investigations of the Hexagonal Germanium Carbonitride

    Directory of Open Access Journals (Sweden)

    Xinhai Yu

    2018-04-01

    Full Text Available The structural, mechanical, elastic anisotropic, and electronic properties of hexagonal germanium carbonitride (h-GeCN are systematically investigated using the first-principle calculations method with the ultrasoft pseudopotential scheme in the frame of generalized gradient approximation in the present work. The h-GeCN are mechanically and dynamically stable, as proved by the elastic constants and phonon spectra, respectively. The h-GeCN is brittle because the ratio B/G and Poisson’s ratio v of the h-GeCN are less than 1.75 and 0.26, respectively. For h-GeCN, from brittleness to ductility, the transformation pressures are 5.56 GPa and 5.63 GPa for B/G and Poisson’s ratio v, respectively. The h-GeCN exhibits the greater elastic anisotropy in Young’s modulus and the sound velocities. In addition, the calculated band structure of h-GeCN reveals that there is no band gap for h-GeCN with the HSE06 hybrid functional, so the h-GeCN is metallic.

  8. The structural and optical properties of metal ion-implanted GaN

    Energy Technology Data Exchange (ETDEWEB)

    Macková, A.; Malinský, P. [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Řež (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, České Mládeže 8, 400 96 Ústí nad Labem (Czech Republic); Sofer, Z.; Šimek, P.; Sedmidubský, D. [Department of Inorganic Chemistry, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Veselý, M. [Dept. of Organic Technology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6 (Czech Republic); Böttger, R. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden – Rossendorf, 01328 Dresden (Germany)

    2016-03-15

    The practical development of novel optoelectronic materials with appropriate optical properties is strongly connected to the structural properties of the prepared doped structures. We present GaN layers oriented along the (0 0 0 1) crystallographic direction that have been grown by low-pressure metal–organic vapour-phase epitaxy (MOVPE) on sapphire substrates implanted with 200 keV Co{sup +}, Fe{sup +} and Ni{sup +} ions. The structural properties of the ion-implanted layers have been characterised by RBS-channelling and Raman spectroscopy to obtain a comprehensive insight into the structural modification of implanted GaN layers and to study the subsequent influence of annealing on crystalline-matrix recovery. Photoluminescence was measured to control the desired optical properties. The post-implantation annealing induced the structural recovery of the modified GaN layer depending on the introduced disorder level, e.g. depending on the ion implantation fluence, which was followed by structural characterisation and by the study of the surface morphology by AFM.

  9. Zone refining high-purity germanium

    International Nuclear Information System (INIS)

    Hubbard, G.S.; Haller, E.E.; Hansen, W.L.

    1977-10-01

    The effects of various parameters on germanium purification by zone refining have been examined. These parameters include the germanium container and container coatings, ambient gas and other operating conditions. Four methods of refining are presented which reproducibly yield 3.5 kg germanium ingots from which high purity (vertical barN/sub A/ - N/sub D/vertical bar less than or equal to2 x 10 10 cm -3 ) single crystals can be grown. A qualitative model involving binary and ternary complexes of Si, O, B, and Al is shown to account for the behavior of impurities at these low concentrations

  10. Influence of a pressure gradient distal to implanted bare-metal stent on in-stent restenosis after percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Thuesen, Leif

    2007-01-01

    pullback recording in the entire length of the artery. METHODS AND RESULTS: In 98 patients with angina pectoris, 1 de novo coronary lesion was treated with a bare-metal stent. After stent implantation, pressure wire measurements (P(d)=mean hyperemic coronary pressure and P(a)=mean aortic pressure) were......-stent restenosis after 9 months. CONCLUSIONS: A residual abnormal P(d)/P(a) distal to a bare-metal stent was an independent predictor of in-stent restenosis after implantation of a coronary bare-metal stent. Udgivelsesdato: 2007-Dec-11......BACKGROUND: Fractional flow reserve predicts cardiac events after coronary stent implantation. The aim of the present study was to assess the 9-month angiographic in-stent restenosis rate in the setting of optimal stenting and a persisting gradient distal to the stent as assessed by a pressure wire...

  11. The effects of dextromethorphan on the outcome of percutaneous coronary intervention with bare-metal stent implantation

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Liu

    2018-01-01

    Full Text Available Background: In the era of drug-eluting stents, although bare-metal stent (BMS remains an option for percutaneous coronary intervention (PCI, restenosis remains the Achilles' heel of BMS implantation. A recent study demonstrated several pleiotropic anti-inflammatory effects of dextromethorphan (DXM. This study aims to evaluate the effects of DXM on the outcome of PCI with BMS implantation.Methods: In this prospective, double-blind, randomized trial, we enrolled 55 patients who underwent PCI with BMS implantation from May 2006 to February 2009. The patients were divided into DXM (60 mg once daily and placebo groups. We compared mortality rates, myocardial infarction (MI, target lesion revascularization (TLR, restenosis, stent thrombosis, and plasma levels of high-sensitivity C-reactive protein (hs-CRP with repeated coronary angiography 6 months after the initial procedure.Results: During the 6-month follow-up period, no events of death, MI and stent thrombosis were reported in both groups. The TLR rate was 16.7% in patients receiving DXM compared to 24% receiving a placebo (P = 0.521. The restenosis rate was 30% in patients receiving DXM as compared to 40% receiving the placebo (P = 0.571. Although nonsignificant, the percentage of hs-CRP elevation was lower in the DXM group (20% compared to the placebo group 32%; P = 0.363.Conclusions: DXM is safe to use in patients who underwent PCI. Although DXM therapy following BMS implantation did not significantly reduce the TLR and restenosis rates, it implied a trend toward a lower TLR and restenosis and reduced inflammation in the DXM group compared to the placebo group. Nonetheless, further extensive studies are warranted to elucidate the anti-restenosis effects of DXM.

  12. AMS INSIGHT--absorbable metal stent implantation for treatment of below-the-knee critical limb ischemia: 6-month analysis.

    Science.gov (United States)

    Bosiers, Marc; Peeters, Patrick; D'Archambeau, Olivier; Hendriks, Jeroen; Pilger, Ernst; Düber, Christoph; Zeller, Thomas; Gussmann, Andreas; Lohle, Paul N M; Minar, Erich; Scheinert, Dierk; Hausegger, Klaus; Schulte, Karl-Ludwig; Verbist, Jürgen; Deloose, Koen; Lammer, J

    2009-05-01

    Endoluminal treatment of infrapopliteal artery lesions is a matter of controversy. Bioabsorbable stents are discussed as a means to combine mechanical prevention of vessel recoil with the advantages of long-term perspectives. The possibility of not having a permanent metallic implant could permit the occurrence of positive remodeling with lumen enlargement to compensate for the development of new lesions. The present study was designed to investigate the safety of absorbable metal stents (AMSs) in the infrapopliteal arteries based on 1- and 6-month clinical follow-up and efficacy based on 6-month angiographic patency. One hundred seventeen patients with 149 lesions with chronic limb ischemia (CLI) were randomized to implantation of an AMS (60 patients, 74 lesions) or stand-alone percutaneous transluminal angioplasty (PTA; 57 patients, 75 lesions). Seven PTA-group patients "crossed over" to AMS stenting. The study population consisted of patients with symptomatic CLI (Rutherford categories 4 and 5) and de novo stenotic (>50%) or occlusive atherosclerotic disease of the infrapopliteal arteries who presented with a reference diameter of between 3.0 and 3.5 mm and a lesion length of <15 mm. The primary safety endpoint was defined as absence of major amputation and/or death within 30 days after index intervention and the primary efficacy endpoint was the 6-month angiographic patency rate as confirmed by core-lab quantitative vessel analysis. The 30-day complication rate was 5.3% (3/57) and 5.0% (3/60) in patients randomized for PTA alone and PTA followed by AMS implantation, respectively. On an intention-to-treat basis, the 6-month angiographic patency rate for lesions treated with AMS (31.8%) was significantly lower (p = 0.013) than the rate for those treated with PTA (58.0%). Although the present study indicates that the AMS technology can be safely applied, it did not demonstrate efficacy in long-term patency over standard PTA in the infrapopliteal vessels.

  13. Metallic stent implantation in patients with iliac artery occlusion: long-term patency rate and factors related to recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seok Kyun; Kim, Jae Kyu; Yoon, Woong; Kim, Jeong; Park, Jin Gyoon; Kang, Heoung Keun; Choi, Soo JinNa [Chonnam National University Hospital School of Medicine, Gwangju (Korea, Republic of)

    2003-09-01

    To determine the long-term patency rate in 68 patients with iliac artery occlusion who underwent metallic stent implantation, and to analyze the factors related to recurrence. Sixty-eight patients with occlusive disease of the iliac artery underwent implantation of a self-expandable metallic stent. The clinical symptoms were intermittent claudication (n=48), resting pain (n=11), and gangrene (n=9). Stent patency was determined by follow-up angiography and color Doppler imaging, and the cumulative patency rate using the Kaplan-Meier method. Cox's proportional hazard model was used to analyse recurrence-related factors involving clinical symptoms (Fontaine stage), risk factors, and anatomical factors such as lesion location, length, and the development of collaterals. The duration of follow-up varied from 1 day to 73 months (mean, 23.8 months). Arterial occlusion recurred in 16 of 68 patients (23.5%), and the cumulative patency rate was as follows: 95.4% at one month, 93.2% at six months, 80.1% at one year, 73.2% at two years, 68.9% at three years, and 62% at five years. According to a statistical analysis of risk factors, the recurrence (p=0.04) than in those without it, but in patients who smoked, hypertension, DM, and previous cerebrovascular disease were not statistically significant. With regard to anatomical factors, the recurrent rate for lesions involving the external iliac artery was 6.5 times higher (p=0.02) than for those involving the common iliac artery. Variations in the fontaine stage were not statistically significant indicators of recurrence. The recurrence rate after implantation of an iliac artery stent is higher in patients with heart disease than in those without it, and higher for occlusive lesions involving the external iliac artery than for those of the common iliac artery.

  14. Metallic stent implantation in patients with iliac artery occlusion: long-term patency rate and factors related to recurrence

    International Nuclear Information System (INIS)

    Chung, Seok Kyun; Kim, Jae Kyu; Yoon, Woong; Kim, Jeong; Park, Jin Gyoon; Kang, Heoung Keun; Choi, Soo JinNa

    2003-01-01

    To determine the long-term patency rate in 68 patients with iliac artery occlusion who underwent metallic stent implantation, and to analyze the factors related to recurrence. Sixty-eight patients with occlusive disease of the iliac artery underwent implantation of a self-expandable metallic stent. The clinical symptoms were intermittent claudication (n=48), resting pain (n=11), and gangrene (n=9). Stent patency was determined by follow-up angiography and color Doppler imaging, and the cumulative patency rate using the Kaplan-Meier method. Cox's proportional hazard model was used to analyse recurrence-related factors involving clinical symptoms (Fontaine stage), risk factors, and anatomical factors such as lesion location, length, and the development of collaterals. The duration of follow-up varied from 1 day to 73 months (mean, 23.8 months). Arterial occlusion recurred in 16 of 68 patients (23.5%), and the cumulative patency rate was as follows: 95.4% at one month, 93.2% at six months, 80.1% at one year, 73.2% at two years, 68.9% at three years, and 62% at five years. According to a statistical analysis of risk factors, the recurrence (p=0.04) than in those without it, but in patients who smoked, hypertension, DM, and previous cerebrovascular disease were not statistically significant. With regard to anatomical factors, the recurrent rate for lesions involving the external iliac artery was 6.5 times higher (p=0.02) than for those involving the common iliac artery. Variations in the fontaine stage were not statistically significant indicators of recurrence. The recurrence rate after implantation of an iliac artery stent is higher in patients with heart disease than in those without it, and higher for occlusive lesions involving the external iliac artery than for those of the common iliac artery

  15. Solution synthesis of germanium nanocrystals

    Science.gov (United States)

    Gerung, Henry [Albuquerque, NM; Boyle, Timothy J [Kensington, MD; Bunge, Scott D [Cuyahoga Falls, OH

    2009-09-22

    A method for providing a route for the synthesis of a Ge(0) nanometer-sized material from. A Ge(II) precursor is dissolved in a ligand heated to a temperature, generally between approximately 100.degree. C. and 400.degree. C., sufficient to thermally reduce the Ge(II) to Ge(0), where the ligand is a compound that can bond to the surface of the germanium nanomaterials to subsequently prevent agglomeration of the nanomaterials. The ligand encapsulates the surface of the Ge(0) material to prevent agglomeration. The resulting solution is cooled for handling, with the cooling characteristics useful in controlling the size and size distribution of the Ge(0) materials. The characteristics of the Ge(II) precursor determine whether the Ge(0) materials that result will be nanocrystals or nanowires.

  16. Usefulness of laser ablation ICP-MS for analysis of metallic particles released to oral mucosa after insertion of dental implants.

    Science.gov (United States)

    Sajnóg, Adam; Hanć, Anetta; Koczorowski, Ryszard; Makuch, Krzysztof; Barałkiewicz, Danuta

    2018-03-01

    Despite the fact that titanium is considered highly biocompatible, its presence in the oral cavity (an environment of frequently changing pH and temperature) may result in the release of titanium from intraosseous implants into the oral mucosa, causing a range of reactions from the human body. Fragments of oral mucosa collected from patients after dental implant insertion were analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The study revealed an elevated content of elements (Ti, Al, V) which are components of the metal implants and temporary cover screws. Dynamic ablation of the tissue surface was used in order to obtain maps of the content and distribution of analyzed elements. The material consisted of 30 oral mucosa tissue fragments collected 3-5 months after implantation and 10 samples collected before implantation (control group). The application of optical microscope allowed for indication and confirmation of the location of metal particles prior to LA-ICP-MS analysis. The so-obtained map permitted location of regions containing metal particles. LA-ICP-MS analysis revealed groups of samples with similar properties of metal particles, thus confirming that those metal particles were the main source of the elevated content of metals (Ti, Al, V) in the tissue after implantation. A calibration strategy based on matrix matched solid standards with powdered egg white proteins as matrix material was applied with 34 S as an internal standard. The accuracy of the analytical method was verified by ablating pellets of certified reference material ERM-BB422 Fish muscle. Copyright © 2017 Elsevier GmbH. All rights reserved.

  17. Ion implantation

    International Nuclear Information System (INIS)

    Johnson, E.

    1986-01-01

    It is the purpose of the present paper to give a review of surface alloy processing by ion implantation. However, rather than covering this vast subject as a whole, the survey is confined to a presentation of the microstructures that can be found in metal surfaces after ion implantation. The presentation is limited to alloys processed by ion implantation proper, that is to processes in which the alloy compositions are altered significantly by direct injection of the implanted ions. The review is introduced by a presentation of the processes taking place during development of the fundamental event in ion implantation - the collision cascade, followed by a summary of the various microstructures which can be formed after ion implantation into metals. This is compared with the variability of microstructures that can be achieved by rapid solidification processing. The microstructures are subsequently discussed in the light of the processes which, as the implantations proceed, take place during and immediately after formation of the individual collision cascades. These collision cascades define the volumes inside which individual ions are slowed down in the implanted targets. They are not only centres for vigorous agitation but also the sources for formation of excess concentrations of point defects, which will influence development of particular microstructures. A final section presents a selection of specific structures which have been observed in different alloy systems. (orig./GSCH)

  18. Restenosis in coronary bare metal stents. Importance of time to follow-up: a comparison of coronary angiograms 6 months and 4 years after implantation

    DEFF Research Database (Denmark)

    Jørgensen, Erik; Helqvist, Steffen; Kløvgaard, Lene

    2008-01-01

    Objectives. Angiographic late lumen loss measured 6 to 9 month after bare metal stent implantation in the coronary arteries is a validated restenosis parameter. Design. We performed a second angiographic follow-up after 4 years in event free survivors from the DANSTENT trial cohort. Results......-sectional vessel area and a 39% reduction of the binary restenosis rate over time. Conclusions. Instent late lumen loss in bare metal stents decreases spontaneously over time. Maturation of early hyperplastic tissue reaction after stent implantation with subsequent thinning of fibrotic tissue might explain...

  19. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces.

    Science.gov (United States)

    Wijesinghe, W P S L; Mantilaka, M M M G P G; Chathuranga Senarathna, K G; Herath, H M T U; Premachandra, T N; Ranasinghe, C S K; Rajapakse, R P V J; Rajapakse, R M G; Edirisinghe, Mohan; Mahalingam, S; Bandara, I M C C D; Singh, Sanjleena

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. SU-E-T-396: Dosimetric Accuracy of Proton Therapy for Patients with Metal Implants in CT Scans Using Metal Deletion Technique (MDT) Artifacts Reduction

    International Nuclear Information System (INIS)

    Li, X; Kantor, M; Zhu, X; Frank, S; Sahoo, N; Li, H

    2014-01-01

    Purpose: To evaluate the dosimetric accuracy for proton therapy patients with metal implants in CT using metal deletion technique (MDT) artifacts reduction. Methods: Proton dose accuracies under CT metal artifacts were first evaluated using a water phantom with cylindrical inserts of different materials (titanium and steel). Ranges and dose profiles along different beam angles were calculated using treatment planning system (Eclipse version 8.9) on uncorrected CT, MDT CT, and manually-corrected CT, where true Hounsfield units (water) were assigned to the streak artifacts. In patient studies, the treatment plans were developed on manually-corrected CTs, then recalculated on MDT and uncorrected CTs. DVH indices were compared between the dose distributions on all the CTs. Results: For water phantom study with 1/2 inch titanium insert, the proton range differences estimated by MDT CT were with 1% for all beam angles, while the range error can be up to 2.6% for uncorrected CT. For the study with 1 inch stainless steel insert, the maximum range error calculated by MDT CT was 1.09% among all the beam angles compared with maximum range error with 4.7% for uncorrected CT. The dose profiles calculated on MDT CTs for both titanium and steel inserts showed very good agreements with the ones calculated on manually-corrected CTs, while large dose discrepancies calculated using uncorrected CTs were observed in the distal end region of the proton beam. The patient study showed similar dose distribution and DVHs for organs near the metal artifacts recalculated on MDT CT compared with the ones calculated on manually-corrected CT, while the differences between uncorrected and corrected CTs were much pronounced. Conclusion: In proton therapy, large dose error could occur due to metal artifact. The MDT CT can be used for proton dose calculation to achieve similar dose accuracy as the current clinical practice using manual correction

  1. Evaluation of Ni-free Zr–Cu–Fe–Al bulk metallic glass for biomedical implant applications

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ying-Sui [Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Zhang, Wei [School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); Kai, Wu [Institute of Materials Engineering, National Taiwan Ocean University, Keelung, Taiwan (China); Liaw, Peter K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN (United States); Huang, Her-Hsiung, E-mail: hhhuang@ym.edu.tw [Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan (China)

    2014-02-15

    Highlights: ► A Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} bulk metallic glass (BMG) with 50 GPa elastic modulus was used. ► This Ni-free Zr-based BMG had lower metal ion release rate than the commercial Ti. ► This Ni-free Zr-based BMG had better proteins adsorption than the commercial Ti. ► This Ni-free Zr-based BMG has a high potential for biomedical implant applications. -- Abstract: This study was conducted to investigate the surface characteristics, including the chemical composition, metal ion release, protein adsorption, and cell adhesion, of a Ni-free Zr-based (Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10}) bulk metallic glass (BMG) with low elastic modulus for biomedical implant applications. X-ray photoelectron spectroscopy was used to identify the surface chemical composition and the protein (albumin and fibronectin) adsorption of the specimen. The metal ions released from the specimen in simulated blood plasma and artificial saliva solutions were measured using an inductively coupled plasma-mass spectrometer. The cell adhesion, in terms of the morphology, focal adhesion complex, and skeletal arrangement, of human bone marrow mesenchymal stem cells was evaluated using scanning electron microscope observations and immunofluorescent staining. For comparison purposes, the above-mentioned tests were also carried out on the widely used biomedical metal, Ti. The results showed that the main component on the outermost surface of the amorphous Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG was ZrO{sub 2} with small amounts of Cu, Al, and Fe oxides. The released metal ions from Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG were well below the critical concentrations that cause negative biological effects. The Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG had a greater adsorption capacity for albumin and fibronectin than that of commercial biomedical Ti. The Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG surface showed an attached cell number similar

  2. Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels.

    Science.gov (United States)

    Guggenberger, R; Winklhofer, S; Osterhoff, G; Wanner, G A; Fortunati, M; Andreisek, G; Alkadhi, H; Stolzmann, P

    2012-11-01

    To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels. Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level. Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, κ = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended. • Artefacts pose problems for CT following posterior spinal fusion implants. • CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT. • DECT extrapolation improves image quality and reduces metallic artefacts over SECT. • There were considerable differences in monoenergy values among vendors and spine levels. • Use of individualised monoenergy values is indicated for different metallic hardware devices.

  3. Off-Resonance Suppression for Multispectral MR Imaging Near Metallic Implants

    NARCIS (Netherlands)

    den Harder, J. Chiel; van Yperen, Gert H.; Blume, Ulrike A.; Bos, Clemens

    Purpose: Metal artifact reduction in MRI within clinically feasible scan-times without through-plane aliasing. Theory and Methods: Existing metal artifact reduction techniques include view angle tilting (VAT), which resolves in-plane distortions, and multispectral imaging (MSI) techniques, such as

  4. Germanium-76 Isotope Separation by Cryogenic Distillation. Final Report

    International Nuclear Information System (INIS)

    Stohler, Eric

    2007-01-01

    The current separation method for Germanium isotopes is electromagnetic separation using Calutrons. The Calutrons have the disadvantage of having a low separation capacity and a high energy cost to achieve the separation. Our proposed new distillation method has the advantage that larger quantities of Germanium isotopes can be separated at a significantly lower cost and in a much shorter time. After nine months of operating the column that is 1.5 meter in length, no significant separation of the isotopes has been measured. We conclude that the length of the column we have been using is too short. In addition, other packing material than the 0.16 inch Propak, 316 ss Protruded metal packing that we used in the column, should be evaluated which may have a better separation factor than the 0.16 inch Propak, 316 ss Protruded metal packing that has been used. We conclude that a much longer column - a minimum of 50 feet length - should be built and additional column packing should be tested to verify that isotopic separation can be achieved by cryogenic distillation. Even a longer column than 50 feet would be desirable.

  5. The Magnetic Properties of Metal-Alloy Glass Composites Prepared by Ion Implantation

    International Nuclear Information System (INIS)

    Julian Fernandez, Cesar de; Mattei, Giovanni; Sada, Cinzia; Maurizio, Chiara; Padovani, Sara; Mazzoldi, Paolo; Sangregorio, Claudio; Gatteschi, Dante

    2003-01-01

    The structural and magnetic properties of Co-Ni, Co-Fe and Ni-Cu alloy nanoparticles formed in silica matrix by sequential ion implantation are presented. These nanoparticles show crystal structure similar to the corresponding bulk alloys. In the Co-Ni and Co-Fe, magnetization saturation and coercive field depend on the the alloy composition, crystal structure and size effects. Ferromagnetic resonance studies show that collective magnetic processes are present and these are determined by the film-like morphology of the implanted region. The temperature dependence of the magnetization of the NixCu100-x samples indicates that their Curie Temperatures are larger than the corresponding bulk ones. This feature is discussed considering the composition of the nanoparticles and the size effects

  6. Transverse maxillary and mandibular growth during and after Bionator therapy: study with metallic implants

    Directory of Open Access Journals (Sweden)

    André da Costa Monini

    2013-06-01

    Full Text Available INTRODUCTION: This study evaluated posteroanterior cephalograms before and after treatment and long term follow-up of Class II division 1 patients treated with bionator. OBJECTIVE: The objective was to demonstrate the transverse growth of maxilla and mandible during and after bionator therapy. METHODS: Measurement of transverse dimensions between posterior maxillary and mandibular implants, as well as the distances between the buccal, gonial and antegonial points were recorded. Measurements were analyzed at three periods: T1 = before bionator therapy, T2 = after bionator therapy and T3 = 5.74 years after T2. RESULTS: There was statistically significant transverse increase due to growth and/or treatment for all variables, except for the distance between the anterior maxillary implants. CONCLUSIONS: During the study period only the anterior maxillary area did not show transverse growth.

  7. Transverse maxillary and mandibular growth during and after bionator therapy: study with metallic implants.

    Science.gov (United States)

    Monini, André da Costa; Júnior, Luiz Gonzaga Gandini; Maia, Luiz Guilherme Martins; Pinto, Ary dos Santos

    2013-01-01

    This study evaluated posteroanterior cephalograms before and after treatment and long term follow-up of Class II division 1 patients treated with bionator. The objective was to demonstrate the transverse growth of maxilla and mandible during and after bionator therapy. Measurement of transverse dimensions between posterior maxillary and mandibular implants, as well as the distances between the buccal, gonial and antegonial points were recorded. Measurements were analyzed at three periods: T1 - before bionator therapy, T2 - after bionator therapy and T3 - 5.74 years after T2. There was statistically significant transverse increase due to growth and/or treatment for all variables, except for the distance between the anterior maxillary implants. During the study period only the anterior maxillary area did not show transverse growth.

  8. The formation of silver metal nanoparticles by ion implantation in silicate glasses

    Czech Academy of Sciences Publication Activity Database

    Vytykačová, S.; Švecová, B.; Nekvindová, P.; Špirková, J.; Macková, Anna; Mikšová, Romana; Bottger, R.

    2016-01-01

    Roč. 371, MAR (2016), s. 245-255 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR GA15-01602S Institutional support: RVO:61389005 Keywords : silicate glasses * silver nanoparticles * ion implantation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  9. RF tissue-heating near metallic implants during magnetic resonance examinations: an approach in the ac limit.

    Science.gov (United States)

    Ballweg, Verena; Eibofner, Frank; Graf, Hansjorg

    2011-10-01

    State of the art to access radiofrequency (RF) heating near implants is computer modeling of the devices and solving Maxwell's equations for the specific setup. For a set of input parameters, a fixed result is obtained. This work presents a theoretical approach in the alternating current (ac) limit, which can potentially render closed formulas for the basic behavior of tissue heating near metallic structures. Dedicated experiments were performed to support the theory. For the ac calculations, the implant was modeled as an RLC parallel circuit, with L being the secondary of a transformer and the RF transmission coil being its primary. Parameters influencing coupling, power matching, and specific absorption rate (SAR) were determined and formula relations were established. Experiments on a copper ring with a radial gap as capacitor for inductive coupling (at 1.5 T) and on needles for capacitive coupling (at 3 T) were carried out. The temperature rise in the embedding dielectric was observed as a function of its specific resistance using an infrared (IR) camera. Closed formulas containing the parameters of the setup were obtained for the frequency dependence of the transmitted power at fixed load resistance, for the calculation of the resistance for optimum power transfer, and for the calculation of the transmitted power in dependence of the load resistance. Good qualitative agreement was found between the course of the experimentally obtained heating curves and the theoretically determined power curves. Power matching revealed as critical parameter especially if the sample was resonant close to the Larmor frequency. The presented ac approach to RF heating near an implant, which mimics specific values for R, L, and C, allows for closed formulas to estimate the potential of RF energy transfer. A first reference point for worst-case determination in MR testing procedures can be obtained. Numerical approaches, necessary to determine spatially resolved heating maps, can

  10. Microstructural and Mechanical Characterization of a Custom-Built Implant Manufactured in Titanium Alloy by Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Larosa

    2014-08-01

    Full Text Available Custom-built implants manufacture has always presented difficulties which result in high cost and complex fabrication, mainly due to patients’ anatomical differences. The solution has been to produce prostheses with different sizes and use the one that best suits each patient. Additive manufacturing technology, incorporated into the medical field in the late 80's, has made it possible to obtain solid biomodels facilitating surgical procedures and reducing risks. Furthermore, this technology has been used to produce implants especially designed for a particular patient, with sizes, shapes, and mechanical properties optimized, for different areas of medicine such as craniomaxillofacial surgery. In this work, the microstructural and mechanical properties of Ti6Al4V samples produced by direct metal laser sintering (DMLS are studied. The microstructural and mechanical characterizations have been made by optical and scanning electron microscopy, X-ray diffraction, and microhardness and tensile tests. Samples produced by DMLS have a microstructure constituted by hexagonal α′ martensite with acicular morphology. An average microhardness of 370 HV was obtained and the tensile tests showed ultimate strength of 1172 MPa, yield strength of 957 MPa, and elongation at rupture of 11%.

  11. Hydroxyapatite-lignin composite as a metallic implant-bone tissue osseointegration improver: experimental study in dogs

    Directory of Open Access Journals (Sweden)

    Fabrício Luciani Valente

    2015-01-01

    Full Text Available The study aimed to evaluate biocompatibility, osteoconduction and osseointegration of a pasty composite of hydroxyapatite (20% and lignin (80% as a promoter of metal implant and bone tissue integration. An intramedullary Schanz pin was implanted in both tibias of fifteen bitches. In the left tibia, the pin was coated with the biomaterial at the time of surgery. Marrow cavity was also filled with the biomaterial. Right limb did not receive the biomaterial, then constituting the control group. Tibias were harvested from five animals at 8, 60 and 150 days after surgery; three of them were analyzed by histological and biomechanical assessment and the two remaining tibias by X-ray diffraction. Results showed that the biomaterial is biocompatible, with osteoconductivity and osseointegration properties. Histological analysis and diffractograms showed the presence of hydroxyapatite in samples in all periods, although the presence of organic material of low crystallinity was variable. There was no statistical difference in the forces required for removal of the biocompatibility, osteoconductivity and osseointegration, it was not able to promote a better intramedullary pin anchorage.

  12. Stent malapposition, as a potential mechanism of very late stent thrombosis after bare-metal stent implantation: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Higuma, Takumi, E-mail: higuma@cc.hirosaki-u.ac.jp; Abe, Naoki; Hanada, Kenji; Yokoyama, Hiroaki; Tomita, Hirofumi; Okumura, Ken

    2014-04-15

    A 90-year-old man was admitted to our hospital with acute ST-segment elevation myocardial infarction. He had a history of post-infarction angina pectoris 79 months ago and had a bare-metal stent (BMS) implanted in the proximal left anterior descending artery at our hospital. Emergent coronary angiography demonstrated thrombotic occlusion in the previously stented segment. After catheter thrombectomy, antegrade flow was restored, but 90% stenosis with haziness persisted in the proximal and distal portions of the previously stented segment. Intravascular ultrasound imaging showed interstrut cavities or stent malapposition at the proximal and distal sites of stented segment. In close proximity to the sites, residual thrombi were also observed. Optical coherence tomography (OCT) demonstrated neither lipid-laden neointimal tissue nor rupture but clearly demonstrated residual thrombus adjacent to the malapposed region in addition to the stent malapposition. PCI with balloon was successfully performed and stent apposition was confirmed by OCT. Stent malapposition is an unusual mechanism of very late stent thrombosis after BMS implantation. OCT can clearly reveal the etiology of stent thrombosis.

  13. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    Science.gov (United States)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-06-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints.

  14. MRI of hip prostheses using single-point methods : in vitro studies towards the artifact-free imaging of individuals with metal implants

    NARCIS (Netherlands)

    Ramos Cabrer, P.; Duynhoven, van J.P.M.; Toorn, van der A.; Nicolaij, K.

    2004-01-01

    Use of magnetic resonance imaging (MRI) in individuals with orthopedic implants is limited because of the large distortions caused by metallic components. As a possible solution for this problem, we suggest the use of single-point imaging (SPI) methods, which are immune to the susceptibility

  15. High energy metal ion implantation using 'Magis', a novel, broad-beam, Marx-generator-based ion source

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.G.; Dickinson, M.R.; MacGill, R.A.

    1996-08-01

    Ion energy of the beam formed by an ion source is proportional to extractor voltage and ion charge state. Increasing the voltage is difficult and costly for extraction voltage over 100 kV. Here we explore the possibility of increasing the charge states of metal ions to facilitate high-energy, broad beam ion implantation at a moderate voltage level. Strategies to enhance the ion charge state include operating in the regimes of high-current vacuum sparks and short pulses. Using a time-of-flight technique we have measured charge states as high as 7+ (73 kA vacuum spark discharge) and 4+ (14 kA short pulse arc discharge), both for copper, with the mean ion charge states about 6.0 and 2.5, respectively. Pulsed discharges can conveniently be driven by a modified Marx generator, allowing operation of ''Magis'' with a single power supply (at ground potential) for both plasma production and ion extraction

  16. Performances of low-dose dual-energy CT in reducing artifacts from implanted metallic orthopedic devices

    Energy Technology Data Exchange (ETDEWEB)

    Filograna, Laura [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Institute of Radiology, Rome (Italy); University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland); Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Institute of Radiology, Rome (Italy); De Waure, Chiara; Calabro, Giovanna Elisa [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Research Centre for Health Technology Assessment, Department of Public Health, Section of Hygiene, Rome (Italy); Finkenstaedt, Tim [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Thali, Michael John [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland)

    2016-07-15

    The objective was to evaluate the performan