Periodontal ligament formation around different types of dental titanium implants. I. The self-tapping screw type implant system

DEFF Research Database (Denmark)

Warrer, K; Karring, T; Gotfredsen, K

1993-01-01

The aim of this study was to determine if a periodontal ligament can form around self-tapping, screw type titanium dental implants. Implants were inserted in contact with the periodontal ligament of root tips retained in the mandibular jaws of 7 monkeys. In each side of the mandible, 1 premolar......, a periodontal ligament can form on self-tapping, screw type titanium dental implants in areas where a void is present between the surrounding bone and the implant at the time of insertion....... and 2 molars were removed in such a manner that in approximately half the cases, the root tips were retained. Following healing, the experimental areas were examined on radiographs, and sites were selected for the insertion of the implants, so that every second implant would have a close contact...

Synthesis, structure, spectral properties and theoretical studies of two half-sandwich titanium-complexes with adamantoxy ligands

Czech Academy of Sciences Publication Activity Database

Varga, Vojtěch; Mach, Karel; Pinkas, Jiří; Kubišta, Jiří; Szarka, K.; Gyepes, R.

2017-01-01

Roč. 1142, AUG 2017 (2017), s. 248-254 ISSN 0022-2860 R&D Projects: GA ČR(CZ) GAP207/12/2368; GA ČR(CZ) GA14-08531S Institutional support: RVO:61388955 Keywords : half-sandwich complex * ionic complex * solid-state structure Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.753, year: 2016

Synergistic responses of superficial chemistry and micro topography of titanium created by wire-type electric discharge machining.

Science.gov (United States)

Kataoka, Yu; Tamaki, Yukimichi; Miyazaki, Takashi

2011-01-01

Wire-type electric discharge machining has been applied to the manufacture of endosseous titanium implants as this computer associated technique allows extremely accurate complex sample shaping with an optimal micro textured surface during the processing. Since the titanium oxide layer is sensitively altered by each processing, the authors hypothesized that this technique also up-regulates biological responses through the synergistic effects of the superficial chemistry and micro topography. To evaluate the respective in vitro cellular responses on the superficial chemistry and micro topography of titanium surface processed by wire-type electric discharge, we used titanium-coated epoxy resin replica of the surface. An oxide layer on the titanium surface processed by wire-type electric discharge activated the initial responses of osteoblastic cells through an integrin-mediated mechanism. Since the mRNA expression of ALP on those replicas was up-regulated compared to smooth titanium samples, the micro topography of a titanium surface processed by wire-type electric discharge promotes the osteogenic potential of cells. The synergistic response of the superficial chemistry and micro topography of titanium processed by wire-type electric discharge was demonstrated in this study.

Bent and linear Uranium(IV) metallocenes with terminal and bridging cyanide ligands

International Nuclear Information System (INIS)

Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.

2007-01-01

Treatment of Cp 2 * UI 2 with KCN in thf led to the formation of Cp 2 * U(CN) 2 (2), which further reacted with NR 4 CN to give [Cp 2 * U(CN) 3 ][ NR 4 ] (R = Et, 3; R = n Bu, 3') and [Cp 2 * U(CN) 5 ][NR 4 ] 3 (R = Et, 4; R n Bu, 4'). While the tri-cyanide 3' adopts the familiar bent sandwich configuration, the penta-cyanide 4 is, after the [Cp 2 * U(NCMe) 5 ] 2+ cation, the second example of a linear metallocene resulting from complete saturation of the equatorial girdle. Compound 3' was also obtained by oxidation of the trivalent compound [Cp 2 * U(CN) 3 ][N n Bu 4 ] 2 ; the rapid and reversible electron transfer between the U(III) and U(IV) complexes was revealed by 1 H NMR spectroscopy. The NMR spectra also revealed that 4 is partially dissociated in thf into 3, providing the first example of an equilibrating couple of bent and linear metallocenes [K = 4.24(4) * 10 -5 at 25 C, ΔH = 199(6) kJ mol -1 , and ΔS = 586(20) J mol -1 K -1 ]. The trinuclear compound [Cp 2 * UCl 2 (μ-CN)] 2 Mg(thf) 4 (1) and the 2D polymeric complex [Cp 2 * U(dmf) 3 -(μ-NC) 2 (AgI) 2 ] n (5), which were obtained during initial attempts on the synthesis of 2-4 and uranium- (V) derivatives, exhibit a bent and linear sandwich structure, respectively. (authors)

Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II)

KAUST Repository

Tonks, Ian A.

2013-06-24

A class of titanium precatalysts of the type (ONO)TiX2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe2) has been synthesized and crystallographically characterized. The (ONO)TiX2 (X = Bn, NMe2, X2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe2, py; R = Ph, tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active TiII species that is generated in situ from 1. Depending on reaction conditions, these TiII species are proposed to be generated through Ti benzylidene or imido intermediates. A formally TiII complex, (ONO)Ti II(η2-C2H4)(HNMe2) (7), has been prepared and structurally characterized. © 2013 American Chemical Society.

Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II)

KAUST Repository

Tonks, Ian A.; Meier, Josef C.; Bercaw, John E.

2013-01-01

A class of titanium precatalysts of the type (ONO)TiX2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe2) has been synthesized and crystallographically characterized. The (ONO)TiX2 (X = Bn, NMe2, X2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe2, py; R = Ph, tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active TiII species that is generated in situ from 1. Depending on reaction conditions, these TiII species are proposed to be generated through Ti benzylidene or imido intermediates. A formally TiII complex, (ONO)Ti II(η2-C2H4)(HNMe2) (7), has been prepared and structurally characterized. © 2013 American Chemical Society.

Infrared spectroscopy and density functional calculations on titanium-dinitrogen complexes

Science.gov (United States)

Yoo, Hae-Wook; Choi, Changhyeok; Cho, Soo Gyeong; Jung, Yousung; Choi, Myong Yong

2018-04-01

Titanium-nitrogen complexes were generated by laser ablated titanium (Ti) atoms and N2 gas molecules in this study. These complexes were isolated on the pre-deposited solid Ar matrix on the pre-cooled KBr window (T ∼ 5.4 K), allowing infrared spectra to be measured. Laser ablation experiments with 15N2 isotope provided distinct isotopic shifts in the infrared spectra that strongly implicated the formation of titanium-nitrogen complexes, Ti(NN)x. Density functional theory (DFT) calculations were employed to investigate the molecular structures, electronic ground state, relative energies, and IR frequencies of the anticipated Ti(NN)x complexes. Based on laser ablation experiments and DFT calculations, we were able to assign multiple Ti(NN)x (x = 1-6) species. Particularly, Ti(NN)5 and Ti(NN)6, which have high nitrogen content, may serve as good precursors in preparing polynitrogens.

Complex compound polyvinyl alcohol-titanic acid/titanium dioxide

Science.gov (United States)

Prosanov, I. Yu.

2013-02-01

A complex compound polyvinyl alcohol-titanic acid has been produced and investigated by means of IR and Raman spectroscopy, X-ray diffraction, and synchronous thermal analysis. It is claimed that it represents an interpolymeric complex of polyvinyl alcohol and hydrated titanium oxide.

Influence of the elastomeric polypropylene addition on the properties of commercial metallocenic polypropylene

Directory of Open Access Journals (Sweden)

Marques Maria de Fátima V.

2001-01-01

Full Text Available Polypropylene with special properties can be obtained by metallocenic catalysts. These catalytic systems represent the beginning of a new age in polyolefins technology. In this work, the influence of the addition of a syndiotactic polypropylene (s-PP on the processability and mechanical properties of a commercial isotactic polypropylene (i-PP obtained by metallocenic catalysts was evaluated. Increasing addition of s-PP promoted better processability, with an increase in the impact strength and a decrease in the stress at break. A reduction of the crystallinity in the polymeric blends was verified. The more significant influence of the s-PP addition was observed for the mi-PP, compared to the ZNi-PP.

Linear uranium metallocenes with polydentate aromatic nitrogen ligands

International Nuclear Information System (INIS)

Berthet, Jean-Claude; Thuery, Pierre; Ephritikhine, Michel; Maynadie, Jerome

2010-01-01

Treatment of [Cp 2 *U(NCMe) 5 ]X 2 [Cp* = C 5 Me 5 , X = BPh 4 (1) or I (1')] or Cp 2 *UI 2 in acetonitrile with the polydentate aromatic nitrogen bases phen, terpy and R 4 btbp led to the formation of the linear uranium metallocenes [Cp 2 *U(NCMe) 3 (phen)]X 2 [X = BPh 4 (2), I (2')], [Cp 2 *U(NCMe) 2 (terpy)][BPh 4 ] 2 (4), [Cp 2 *U(NCMe)(Me 4 btbp)][BPh 4 ] 2 (5) and [Cp 2 *U(NCMe)(CyMe 4 btbp)][X] 2 , [X = BPh 4 (6), I (6')], [phen 1, 10-phenanthroline, terpy = 2, 2':6, 2''-terpyridine, Me 4 btbp 6, 6'-bis-(3, 3, 6, 6-tetramethyl-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine, CyMe 4 btbp = 6, 6'-bis-(3, 3, 6, 6-tetramethyl-cyclohexane-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine]. The bent metallocene [Cp 2 *U(phen) 2 ][BPh 4 ] 2 (3) was isolated from the reaction of 1 and two molar equivalents of phen in THF. The X-ray crystal structures of 2.2MeCN, 3.2THF, 4 and 6'center dot 2MeCN were determined. (authors)

Synthesis of ferrocenestrone: the first metallocene based steroid analogue

Czech Academy of Sciences Publication Activity Database

Hessler, F.; Císařová, I.; Sedlák, David; Bartůněk, Petr; Kotora, Martin

2012-01-01

Roč. 18, č. 18 (2012), s. 5515-5518 ISSN 0947-6539 R&D Projects: GA MŠk(CZ) 1M0508; GA ČR GA204/09/1905; GA MŠk(CZ) LC06077 Institutional support: RVO:68378050 ; RVO:61388963 Keywords : asymmetric synthesis * ferrocenestrones * metallocenes * steroids * synthesis design Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.831, year: 2012

Rhodium-catalyzed enantioselective intramolecular C-H silylation for the syntheses of planar-chiral metallocene siloles.

Science.gov (United States)

Zhang, Qing-Wei; An, Kun; Liu, Li-Chuan; Yue, Yuan; He, Wei

2015-06-01

Reported herein is the rhodium-catalyzed enantioselective C-H bond silylation of the cyclopentadiene rings in Fe and Ru metallocenes. Thus, in the presence of (S)-TMS-Segphos, the reactions took place under very mild conditions to afford metallocene-fused siloles in good to excellent yields and with ee values of up to 97%. During this study it was observed that the steric hindrance of chiral ligands had a profound influence on the reactivity and enantioselectivity of the reaction, and might hold the key to accomplishing conventionally challenging asymmetric C-H silylations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium

International Nuclear Information System (INIS)

Zou, Minmin; Li, Jing-Feng; Kita, Takuji

2013-01-01

Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV 0.8 Ti 0.4 Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 °C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 °C, which is relatively high for p-type half-Heusler alloys. Highlights: ► Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. ► Substituting V with Ti changes the electrical behavior from n-type to p-type. ► Thermoelectric properties are improved by optimizing sintering temperature. ► Thermoelectric properties are further improved by applying annealing treatment. ► A high ZT value of 0.43 is obtained at 500 °C for p-type Ti-doped FeVSb alloys.

Arylimido zirconium and titanium complexes. Characteristic structures and application in ethylene polymerization

Energy Technology Data Exchange (ETDEWEB)

Yuan, Shifang; Zhang, Jing [Shanxi Univ., Taiyuan (China). Inst. of Applied Chemistry; Wang, Lijing [Shanxi Univ., Taiyuan (China). School of Chemistry and Chemical Engineering; Hua, Yupeng [Shanxi Univ., Taiyuan (China). School of Chemistry and Chemical Engineering; Inner Mongolia Univ., Ordos (China). College of Ordos; Sun, Wen-Hua [Chinese Academy of Sciences, Beijing (China). Key Laboratory of Engineering Plastics

2016-07-01

Dimeric anilidolithium (ArHNLi.Et{sub 2}O){sub 2} (Ar=2,6-{sup i}Pr{sub 2}C{sub 6}H{sub 3}) reacted with zirconium tetrachloride in THF to give the heterometallic zirconium-lithium complex [(Et{sub 2}O){sub 2}Li(μ-Cl){sub 2}(ArHN)(ArN=)Zr(μ-Cl)]{sub 2} (C1) and with titanium tetrachloride in toluene to give the titanium complex [(ArN=)TiCl{sub 2}.(Et{sub 2}O){sub 2}] (C2) each in good isolated yields. Their molecular structures in the solid state were confirmed by X-ray diffraction analysis. Upon activation with methylaluminoxane, both arylimido zirconium and titanium complexes exhibited good catalytic activities toward ethylene polymerization.

Mechanical properties and fracture of titanium hydrides

International Nuclear Information System (INIS)

Koketsu, Hideyuki; Taniyama, Yoshihiro; Yonezu, Akio; Cho, Hideo; Ogawa, Takeshi; Takemoto, Mikio; Nakayama, Gen

2006-01-01

Titanium hydrides tend to suffer fracture when their thicknesses reach a critical thickness. Morphology and mechanical property of the hydrides are, however, not well known. The study aims to reveal the hydride morphology and fracture types of the hydrides. Chevron shaped plate hydrides were found to be produced on the surface of pure titanium (Grade 1) and Grade 7 titanium absorbing hydrogen. There were tree types of fracture of the hydrides, i.e., crack in hydride layer, exfoliation of the layer and shear-type fracture of the hydride plates, during the growth of the hydrides and deformation. We next estimated the true stress-strain curves of the hydrides on Grade 1 and 7 titanium using the dual Vickers indentation method, and the critical strain causing the Mode-I fine crack by indentation. Fracture strength and strain of the hydrides in Grade 1 titanium were estimated as 566 MPa and 4.5%, respectively. Those of the hydride in Grade 7 titanium were 498 MPa and 16%. Though the fracture strains estimated from the plastic instability of true stress-strain curves were approximately the half of those estimated by finite element method, the titanium hydrides were estimated to possess some extent of toughness or plastic deformation capability. (author)

Linear uranium metallocenes with polydentate aromatic nitrogen ligands

Energy Technology Data Exchange (ETDEWEB)

Berthet, Jean-Claude; Thuery, Pierre; Ephritikhine, Michel [CEA, DSM/IRAMIS, UMR 3299 CEA/CNRS SIS2M, 91191, Gif-sur-Yvette (France); Maynadie, Jerome [CEA ValRho, DEN/MAR/ICSM/LCPA, 30207 Bagnols-sur-Ceze (France)

2010-07-01

Treatment of [Cp{sub 2}*U(NCMe){sub 5}]X{sub 2} [Cp* = C{sub 5}Me{sub 5}, X = BPh{sub 4} (1) or I (1')] or Cp{sub 2}*UI{sub 2} in acetonitrile with the polydentate aromatic nitrogen bases phen, terpy and R{sub 4}btbp led to the formation of the linear uranium metallocenes [Cp{sub 2}*U(NCMe){sub 3}(phen)]X{sub 2} [X = BPh{sub 4} (2), I (2')], [Cp{sub 2}*U(NCMe){sub 2}(terpy)][BPh{sub 4}]{sub 2} (4), [Cp{sub 2}*U(NCMe)(Me{sub 4}btbp)][BPh{sub 4}]{sub 2} (5) and [Cp{sub 2}*U(NCMe)(CyMe{sub 4}btbp)][X]{sub 2}, [X = BPh{sub 4} (6), I (6')], [phen 1, 10-phenanthroline, terpy = 2, 2':6, 2''-terpyridine, Me{sub 4}btbp 6, 6'-bis-(3, 3, 6, 6-tetramethyl-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine, CyMe{sub 4}btbp = 6, 6'-bis-(3, 3, 6, 6-tetramethyl-cyclohexane-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine]. The bent metallocene [Cp{sub 2}*U(phen){sub 2}][BPh{sub 4}]{sub 2} (3) was isolated from the reaction of 1 and two molar equivalents of phen in THF. The X-ray crystal structures of 2.2MeCN, 3.2THF, 4 and 6'center dot 2MeCN were determined. (authors)

Branching structure and strain hardening of branched metallocene polyethylenes

International Nuclear Information System (INIS)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M.

2015-01-01

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers

Branching structure and strain hardening of branched metallocene polyethylenes

Energy Technology Data Exchange (ETDEWEB)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M., E-mail: john.dealy@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 0C4 (Canada)

2015-09-15

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers.

Is the bipyridyl thorium metallocene a low-valent thorium complex? A combined experimental and computational study

Energy Technology Data Exchange (ETDEWEB)

Ren, Wenshan; Lukens, Wayne W.; Zi, Guofu; Maron, Laurent; Walter, Marc D.

2012-01-12

Bipyridyl thorium metallocenes [5-1,2,4-(Me3C)3C5H2]2Th(bipy) (1) and [5-1,3-(Me3C)2C5H3]2Th(bipy) (2) have been investigated by magnetic susceptibility and computational studies. The magnetic susceptibility data reveal that 1 and 2 are not diamagnetic, but they behave as temperature independent paramagnets (TIPs). To rationalize this observation, density functional theory (DFT) and complete active space SCF (CASSCF) calculations have been undertaken, which indicated that Cp2Th(bipy) has indeed a Th(IV)(bipy2-) ground state (f0d0 2, S = 0), but the open-shell singlet (f0d1 1, S = 0) (almost degenerate with its triplet congener) is lying only 9.2 kcal/mol higher in energy. Complexes 1 and 2 react cleanly with Ph2CS to give [ 5-1,2,4-(Me3C)3C5H2]2Th[(bipy)(SCPh2)] (3) and [ 5-1,3-(Me3C)2C5H3]2Th[(bipy)(SCPh2)] (4), respectively, in quantitative conversions. Since no intermediates were observed experimentally, this reaction was also studied computationally. Coordination of Ph2CS to 2 in its S = 0 ground state is not possible, but Ph2CS can coordinate to 2 in its triplet state (S = 1) upon which a single electron transfer (SET) from the (bipy2-) fragment to Ph2CS followed by C-C coupling takes place.

ct-DNA Binding and Antibacterial Activity of Octahedral Titanium (IV Heteroleptic (Benzoylacetone and Hydroxamic Acids Complexes

Directory of Open Access Journals (Sweden)

Raj Kaushal

2016-01-01

Full Text Available Five structurally related titanium (IV heteroleptic complexes, [TiCl2(bzac(L1–4] and [TiCl3(bzac(HL5]; bzac = benzoylacetonate; L1–5 = benzohydroximate (L1, salicylhydroximate (L2, acetohydroximate (L3, hydroxyurea (L4, and N-benzoyl-N-phenyl hydroxylamine (L5, were used for the assessment of their antibacterial activities against ten pathogenic bacterial strains. The titanium (IV complexes (1–5 demonstrated significant level of antibacterial properties as measured using agar well diffusion method. UV-Vis absorption spectroscopic technique was applied, to get a better insight into the nature of binding between titanium (IV complexes with calf thymus DNA (ct-DNA. On the basis of the results of UV-Vis absorption spectroscopy, the interaction between ct-DNA and the titanium (IV complexes is likely to occur through the same mode. Results indicated that titanium (IV complex can bind to calf thymus DNA (ct-DNA via an intercalative mode. The intrinsic binding constant (Kb was calculated by absorption spectra by using Benesi-Hildebrand equation. Further, Gibbs free energy was also calculated for all the complexes.

Titanium and titanium alloys: fundamentals and applications

National Research Council Canada - National Science Library

Leyens, C; Peters, M

2003-01-01

... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

Peroxy-Titanium Complex-based inks for low temperature compliant anatase thin films.

Science.gov (United States)

Shabanov, N S; Asvarov, A Sh; Chiolerio, A; Rabadanov, K Sh; Isaev, A B; Orudzhev, F F; Makhmudov, S Sh

2017-07-15

Stable highly crystalline titanium dioxide colloids are of paramount importance for the establishment of a solution-processable library of materials that could help in bringing the advantages of digital printing to the world of photocatalysis and solar energy conversion. Nano-sized titanium dioxide in the anatase phase was synthesized by means of hydrothermal methods and treated with hydrogen peroxide to form Peroxy-Titanium Complexes (PTCs). The influence of hydrogen peroxide on the structural, optical and rheological properties of titanium dioxide and its colloidal solutions were assessed and a practical demonstration of a low temperature compliant digitally printed anatase thin film given. Copyright © 2017 Elsevier Inc. All rights reserved.

Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

Energy Technology Data Exchange (ETDEWEB)

Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

2015-03-02

A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

Energy Technology Data Exchange (ETDEWEB)

Sofield, Chadwick Dean [Univ. of California, Berkeley, CA (United States)

2000-05-01

Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me₂Si[(Me₃C)₂C₅H₃]₂), ansa-bis(trimethylsilyl)cyclopentadiene (Me₂Si[(Me₃Si)₂C₅H₃]₂) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me₃C)₂C₅H₃]₂Mn and [(Me₃

Effects of Electron Beam Irradiation on Binary Polyamide-6 Blends with Metallocene Copolymers

International Nuclear Information System (INIS)

Rosales, C.

2006-01-01

A versatile way to produce new materials with high Izod impact strength and reduced heat deformations is the irradiation of compatibilized blends. The effect of electron beam irradiation and different types of dispersed phase grafted copolymers on thermal and mechanical properties, and SEM morphology of polyamide-6 (PA-6) blends were investigated. Two metallocene copolymers (mEPDM and mPOE) grafted in-situ with maleic anhydride and two commercial maleated copolymers (EPDM-g-MA and mEPR-g-MA) were employed in binary blends with PA6 as matrix. The blends were prepared by extrusion with a composition of 80 wt. % of PA-6. The influence of the radical or functional groups generated in the grafting and the irradiation processes (25, 50, 100 and 200 kGy) was found by ATR-FTIR. The blends exhibited the characteristic thermal behavior of immiscible systems. All compatibilizers employed influenced the melting and crystallization behavior of the blend components without irradiation and an improvement in interface adhesion was clearly observed by SEM micrographs. The sizes of the dispersed phase in the non-irradiated reactive blends were in agreement with the viscosity ratios of the blend components. High toughness materials were obtained with ethylene-polypropylene-diene (mEPDM) grafted copolymers without significant variations in their thermal properties and Izod impact strength at room temperature and -30 degree with the irradiation doses. However, the toughness of the blends with grafted metallocene polyethylenes was affected by the irradiation doses employed. Therefore, the gel content and tensile properties of the samples depended on the chain scission, crosslinking and/or grafting reactions of the blend components

One half of a prototype titanium vacuum chamber

CERN Multimedia

CERN PhotoLab

1973-01-01

Designed and constructed in the ISR Department, it could be for general use at intersection regions. The use of titanium instead of stainless steel increases the "transparency" to particles by a factor of about two for the same wall thickness.

Titanium

Science.gov (United States)

Woodruff, Laurel G.; Bedinger, George M.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Titanium is a mineral commodity that is essential to the smooth functioning of modern industrial economies. Most of the titanium produced is refined into titanium dioxide, which has a high refractive index and is thus able to impart a durable white color to paint, paper, plastic, rubber, and wallboard. Because of their high strength-to-weight ratio and corrosion resistance, titanium metal and titanium metal alloys are used in the aerospace industry as well as for welding rod coatings, biological implants, and consumer goods.Ilmenite and rutile are currently the principal titanium-bearing ore minerals, although other minerals, including anatase, perovskite, and titanomagnetite, could have economic importance in the future. Ilmenite is currently being mined from two large magmatic deposits hosted in rocks of Proterozoic-age anorthosite plutonic suites. Most rutile and nearly one-half of the ilmenite produced are from heavy-mineral alluvial, fluvial, and eolian deposits. Titanium-bearing minerals occur in diverse geologic settings, but many of the known deposits are currently subeconomic for titanium because of complications related to the mineralogy or because of the presence of trace contaminants that can compromise the pigment production process.Global production of titanium minerals is currently dominated by Australia, Canada, Norway, and South Africa; additional amounts are produced in Brazil, India, Madagascar, Mozambique, Sierra Leone, and Sri Lanka. The United States accounts for about 4 percent of the total world production of titanium minerals and is heavily dependent on imports of titanium mineral concentrates to meet its domestic needs.Titanium occurs only in silicate or oxide minerals and never in sulfide minerals. Environmental considerations for titanium mining are related to waste rock disposal and the impact of trace constituents on water quality. Because titanium is generally inert in the environment, human health risks from titanium and titanium

High performance p-type half-Heusler thermoelectric materials

Science.gov (United States)

Yu, Junjie; Xia, Kaiyang; Zhao, Xinbing; Zhu, Tiejun

2018-03-01

Half-Heusler compounds, which possess robust mechanical strength, good high temperature thermal stability and multifaceted physical properties, have been verified as a class of promising thermoelectric materials. During the last two decades, great progress has been made in half-Heusler thermoelectrics. In this review, we summarize some representative work of p-type half-Heusler materials, the thermoelectric performance of which has been remarkably enhanced in recent years. We introduce the features of the crystal and electronic structures of half-Heusler compounds, and successful strategies for optimizing electrical and thermal transport in the p-type RFeSb (R  =  V, Nb, Ta) and MCoSb (M  =  Ti, Zr, Hf) based systems, including band engineering, the formation of solid solutions and hierarchical phonon scattering. The outlook for future research directions of half-Heusler thermoelectrics is also presented.

The effects of different types of investments on the alpha-case layer of titanium castings.

Science.gov (United States)

Guilin, Yu; Nan, Li; Yousheng, Li; Yining, Wang

2007-03-01

Different types of investments affect the formation of the alpha-case (alpha-case) layer on titanium castings. This alpha-case layer may possibly alter the mechanical properties of cast titanium, which may influence the fabrication of removable and fixed prostheses. The formation mechanism for the alpha-case layer is not clear. The aim of this study was to evaluate the effect of 3 types of investments on the microstructure, composition, and microhardness of the alpha-case layer on titanium castings. Fifteen wax columns with a diameter of 5 mm and a length of 40 mm were divided into 3 groups of 5 patterns each. Patterns were invested using 3 types of investment materials, respectively, and were cast in pure titanium. The 3 types of materials tested were SiO(2)-, Al(2)O(3)-, and MgO-based investments. All specimens were sectioned and prepared for metallographic observation. The microstructure and composition of the surface reaction layer of titanium castings were investigated by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The surface microhardness (VHN) for all specimens was measured using a hardness testing machine, and a mean value for each group was calculated. The alpha-case layer on titanium castings invested with SiO(2)-, Al(2)O(3)-, and MgO-based investments consisted of 3 layers-namely, the oxide layer, alloy layer, and hardening layer. In this study, the oxide layer and alloy layer were called the reaction layer. The thickness of the reaction layer for titanium castings using SiO(2)-, Al(2)O(3)-, and MgO-based investments was approximately 80 microm, 50 microm, and 14 microm, respectively. The surface microhardness of titanium castings made with SiO(2)-based investments was the highest, and that with MgO-based investments was the lowest. The type of investment affects the microstructure and microhardness of the alpha-case layer of titanium castings. Based on the thickness of the surface reaction layer and the surface

Research and Application of New Type of High Performance Titanium Alloy

Directory of Open Access Journals (Sweden)

ZHU Zhishou

2016-06-01

Full Text Available With the continuous extension of the application quantity and range for titanium alloy in the fields of national aviation, space, weaponry, marine and chemical industry, etc., even more critical requirements to the comprehensive mechanical properties, low cost and process technological properties of titanium alloy have been raised. Through the alloying based on the microstructure parameters design, and the comprehensive strengthening and toughening technologies of fine grain strengthening, phase transformation and process control of high toughening, the new type of high performance titanium alloy which has good comprehensive properties of high strength and toughness, anti-fatigue, failure resistance and anti-impact has been researched and manufactured. The new titanium alloy has extended the application quantity and application level in the high end field, realized the industrial upgrading and reforming, and met the application requirements of next generation equipment.

MESOPOROUS ACID SOLID AS A CARRIER FOR METALLOCENE CATALYST IN ETHYLENE POLYMERIZATION AND A CATALYST IN CATALYTIC DEGRADATION OF POLYETHYLENE

Institute of Scientific and Technical Information of China (English)

Wen-xi Cheng; Li-ya Shi; Shi-yun Li; Hui Chen; Tao Tang

2007-01-01

The possibility of mesoporous acid solid as a carrier for metallocene catalyst in ethylene polymerization and catalyst for polyethylene(PE)catalytic degradation was investigated.Here,HMCM-41 and AlMCM-41.and mesoporous silicoaluminophosphate molecular sieves(SAPO1 and SAPO2)were synthesized and used as acid solid.Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing.The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAO1 mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1.supported metallocene catalyst.This work shows a novel technology for chemical recycling of polyolefin.

Controlled synthesis of titania using water-soluble titanium complexes: A review

Science.gov (United States)

Truong, Quang Duc; Dien, Luong Xuan; Vo, Dai-Viet N.; Le, Thanh Son

2017-07-01

The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research.

Pulse-radiolytic investigation of the reduction of titanium(III) ions in aqueous solutions

International Nuclear Information System (INIS)

Micic, O.I.; Nenadovic, M.T.

1979-01-01

The absorption spectrum and decay kinetics of intermediates formed by the reaction of titanium(III) ions with H atoms, hydrated electrons, and carboxyl radicals have been studied in aqueous solution using the pulse-radiolysis technique. The product of the reaction with H atoms in acid solution is a Ti 3+ -H hydride intermediate which decomposes by a first-order process with a half-life of ca. 3 s. Titanium(II) is formed by reaction with hydrated electrons and CO 2 H radicals. The absorption spectrum of titanium(II) and the kinetics of its reactions are reported and discussed. The formation of molecular hydrogen by reaction of Ti 2+ with water is suppressed by the other solutes in the solutions. Titanium(III) reacts with CO 2 H, CH 2 CO 2 H, and CH(CO 2 H) 2 radicals to give titanium-radical complexes. (author)

[Torque resistance of three different types of nickel-titanium rotary instruments].

Science.gov (United States)

Sun, Wei; Hou, Ben-xiang

2010-10-01

To compare torsional fracture of three different types of nickel-titanium rotary instruments ProTaper, Hero642 and Mtwo by making a stimulate models in vitro. Through the establishment of model in vitro, compared the different time with 3 kinds of nickel titanium file in cutting-edge bound occurs, and to observe the section of fractured instruments by scanning electron microscope. The resistence to torque was different from three types of nickel titanium instruments. The time to fracture of Mtwo was significantly longer than ProTaper's and Hero642's, but ProTaper's and Hero642's had no significant difference. Three kinds cross-sectional design were different, a lot of toughness nests were seen in broken surface. Most of them were ductile fracture. Time to fracture was influenced by the quality disfigurement. The resistance to torque of Mtwo was better than ProTaper and Hero642. The lifespan was influenced by the design of cross-section. The quality disfigurement of the files reduced the resistance to flexual fatigue.

Titanium ; dream new material

International Nuclear Information System (INIS)

Lee, Yong Tae; Kim Seung Eon; Heoon, Yong Taek; Jung, Hui Won

2001-11-01

The contents of this book are history of Titanium, present situation of Titanium industry, property of Titanium alloy, types of it, development of new alloy of Titanium smelting of Titanium, cast of Titanium and heat treatment of Titanium, Titanium alloy for plane, car parts, biological health care, and sport leisure and daily life, prospect, and Titanium industrial development of Titanium in China.

Computational Study of the Effect of Confinement within Microporous Structures on the Activity and Selectivity of Metallocene Catalysts for Ethylene Oligomerization

KAUST Repository

Toulhoat, Hervé; Lontsi Fomena, Mireille; de Bruin, Theodorus

2011-01-01

The effect of confinement within some zeolitic structures on the activity and selectivity of metallocene catalysts for the ethylene oligomerization has been investigated using grand canonical Monte Carlo simulations (GCMC). The following zeolite

Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

International Nuclear Information System (INIS)

Roner, Michael R; Carraher, Charles E Jr; Shahi, Kimberly; Ashida, Yuki; Barot, Girish

2009-01-01

Monomeric Group IVB (Ti, Zr and Hf) metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort. For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results. The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin. These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of the drugs is straight forward

Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

Directory of Open Access Journals (Sweden)

Ashida Yuki

2009-10-01

Full Text Available Abstract Background Monomeric Group IVB (Ti, Zr and Hf metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort. Methods For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results. Results The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin. Conclusion These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of

Chromatographic retention of molybdenum, titanium and uranium complexes for removal of some interferences in inductively-coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Jiang, S.-J.; Palmieri, M.D.; Fritz, J.S.; Houk, R.S.; Iowa State Univ., of Science and Technology, Ames

1987-01-01

Complexes of molybdenum(VI) or titanium(IV) with N-methylfurohydroxamic acid (N-MFHA) are retained on a column packed with polystyrene/divinylbenzene. At the pH values chosen, copper, zinc and cadmium are washed rapidly through the column and are detected by inductively-coupled plasma mass spectrometry without interference from metal oxide ions of titanium or molybdenum. Detection limits are 1 to 2 μg l -1 , and analyte recoveries are essentially 100%. The resin capacity for the titanium and molybdenum complexes is sufficient for several hundred injections, and the complexes can be readily washed from the column. Uranium(VI) also forms a stable complex with N-MFHA, and ionization interference caused by excess of uranium can be avoided by chromatographic removal of the uranium complex. Various other potentially interfering elements with aqueous oxidation states of +4 or higher (e.g. Sn, W, Hf or Zr) could also be separated by this technique. 33 refs.; 4 figs.; 3 tabs

[Comparison of fibroblastic cell compatibility of type I collagen-immobilized titanium between electrodeposition and immersion].

Science.gov (United States)

Kyuragi, Takeru

2014-03-01

Titanium is widely used for medical implants. While many techniques for surface modification have been studied for optimizing its biocompatibility with hard tissues, little work has been undertaken to explore ways of maximizing its biocompatibility with soft tissues. We investigated cell attachment to titanium surfaces modified with bovine Type I collagen immobilized by either electrodeposition or a conventional immersion technique. The apparent thickness and durability of the immobilized collagen layer were evaluated prior to incubation of the collagen-immobilized titanium surfaces with NIH/3T3 mouse embryonic fibroblasts. The initial cell attachment and expression of actin and vinculin were evaluated. We determined that the immobilized collagen layer was much thicker and more durable when placed using the electrodeposition technique than the immersion technique. Both protocols produced materials that promoted better cell attachment, growth and structural protein expression than titanium alone. However, electrodeposition was ultimately superior to immersion because it is quicker to perform and produces a more durable collagen coating. We conclude that electrodeposition is an effective technique for immobilizing type I collagen on titanium surfaces, thus improving their cytocompatibility with fibroblasts.

Structure and properties of Titanium for dental implants

Directory of Open Access Journals (Sweden)

M. Greger

2009-10-01

Full Text Available This paper describes manufacture of nano-structural titanium, its structure and properties. Nano-titanium has higher specific strength properties than ordinary (coarse-grained titanium. Nano-titanium was produced by the equal-channel angular pressing (ETAP process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of nano-titanium varies around 960 MPa, grain size around 300 nm.

Radiolysis of titanium potassium oxalate in aqueous solution. [. gamma. rays

Energy Technology Data Exchange (ETDEWEB)

Bundo, Y; Ono, I [Industrial Research Inst. of Kanagawa Prefecture, Yokohama (Japan); Ogawa, T

1975-01-01

The dissolution state of titanium potassium oxalate in aqueous solution is different according to the pH. The yellowish brown titanium complex produced by the reaction of titanium potassium oxalate and hydrogen peroxide seems to be different in its structure according to the pH. Considering these points, gamma-ray irradiation was carried out on the sample by dissolving titanium potassium oxalate in purified water under the conditions of oxygen saturation and nitrogen saturation, and the relation between irradiation dose and the production of titanium complex was determined. On the basis of the experimental result, the mechanism of forming hydrogen peroxide was presumed. The radiation source used was 2,000 Ci of /sup 60/Co. For photometric analysis, a 139 type photoelectric spectrophotometer of Hitachi Ltd. was used. From the experimental results, in neutral water, titanium potassium oxalate exists in the state that two oxalic acid ions are coordinated to titanyl ion, while in case of the pH lowered by the addition of sulfuric acid, it can exist in the state that one oxalic acid ion is coordinated to titanyl ion. The yield of hydrogen peroxide produced by irradiating titanium potassium oxalate aqueous solution with gamma-ray is the sum of the molecular product from water and the radiolysis product from titanium potassium oxalate.

SART-Type Half-Threshold Filtering Approach for CT Reconstruction.

Science.gov (United States)

Yu, Hengyong; Wang, Ge

2014-01-01

The [Formula: see text] regularization problem has been widely used to solve the sparsity constrained problems. To enhance the sparsity constraint for better imaging performance, a promising direction is to use the [Formula: see text] norm (0 < p < 1) and solve the [Formula: see text] minimization problem. Very recently, Xu et al. developed an analytic solution for the [Formula: see text] regularization via an iterative thresholding operation, which is also referred to as half-threshold filtering. In this paper, we design a simultaneous algebraic reconstruction technique (SART)-type half-threshold filtering framework to solve the computed tomography (CT) reconstruction problem. In the medical imaging filed, the discrete gradient transform (DGT) is widely used to define the sparsity. However, the DGT is noninvertible and it cannot be applied to half-threshold filtering for CT reconstruction. To demonstrate the utility of the proposed SART-type half-threshold filtering framework, an emphasis of this paper is to construct a pseudoinverse transforms for DGT. The proposed algorithms are evaluated with numerical and physical phantom data sets. Our results show that the SART-type half-threshold filtering algorithms have great potential to improve the reconstructed image quality from few and noisy projections. They are complementary to the counterparts of the state-of-the-art soft-threshold filtering and hard-threshold filtering.

Mean-square displacement of atomic complex in titanium carbonitrides TiCxNy

International Nuclear Information System (INIS)

Khidirov, I.; Sultanova, S.Kh.; Mukhtarova, N.N.; Tokhtashev, B.

2004-01-01

Full text: The atomic mean-square displacement (MSD) is one of important characteristics of solids, and one can use it for determination of a number of other characteristics of substances. In this work the MSD of atomic complex were determined for a number of compositions of the cubic titanium carbonitrides TiC x N y using the neutron powder diffraction data. The error of MSD determination was less than 3 %. When determining intensity of diffraction maximum a correction for the thermal diffusion dispersion (TDD) was included in the neutron diffraction patterns. The contribution of TDD in the intensity of diffraction maxima was found to be less than the experiment error (no more than 1,5 %). Such small value of the TDD correction is explained by refractory of materials. The values of MSD in titanium carbonitrides for a number of compositions, determined by the neutron powder diffraction measurements, are given. It is shown, that the dependence of MSD on the concentration (C+N)/Ti has a complex character. With decrease of the total content of metalloids MSD decreases at first, reaching a minimum about concentration (C+N)/Ti≅0.80, and then increases. MSD consists of dynamic and static distortions, where the static distortions in the compounds with variable composition increase with increasing of deviation from stoichiometry. The above anomaly in the dependence of MSD on the total concentration of metalloids, apparently, point to prevalence of dynamic distortions over static ones and to complex character of concentration dependence of interatomic interactions in the titanium carbonitrides. This work was supported by the Supporting Fund for Fundamental Researches of Uzbekistan Academy of Sciences (Grant No. 6-04)

Cyanide metallocenes of trivalent f-elements

International Nuclear Information System (INIS)

Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.

2007-01-01

Addition of N n Bu 4 CN to (C 5 Me 5 ) 2 UI(py), (C 5 Me 5 ) 2 CeI, or (C 5 Me 5 ) 2 M(OTf) (M = U, Ce) in acetonitrile led to the precipitation of the neutral mono-cyanide species [(C 5 Me 5 ) 2 M(μ-CN)] n [M = U (1), Ce (2)], which likely have an oligomeric structure, as shown by the tri-meric cyanide-bridged complex [(C 5 Me 5 ) 2 Ce(μ-CN)(CN t Bu)] 3 (3) obtained by addition of excess t BuNC into a suspension of 2 in acetonitrile. The structure of the U(III,IV) mixed valence compound [{(C 5 Me 5 ) 2 U} 2 (μ-CN){(μ-CN) 2 Na(thf)} 2 ] ∞ (4), which crystallized from a thf solution of (C 5 Me 5 ) 2 UI(py) in the presence of excess NaCN, reveals a unique example of an f-element-(μ-CN)-M interaction (M = main group or d transition metal). The anionic poly-cyanides [(C 5 Me 5 ) 2 M(CN) 3 ][N n Bu 4 ] 2 [M = U (5), Ce (6)] were synthesized by treatment of 1 and 2 with 2 equiv or an excess of N n Bu 4 CN in acetonitrile; they were also prepared in a one-pot procedure by stepwise addition of 1 equiv of KCN and 2 equiv of N n Bu 4 CN to the parent iodides in acetonitrile. The bent metallocenes 5 and 6 are unique low-valent molecular poly-cyanide compounds of an f-element that have been structurally identified, while 5 is the first fully characterized actinide(III) cyanide. Comparison of the crystal structures of 5 and 6 shows that the M-C(C 5 Me 5 ) and M-C(CN) distances are 0.02-0.03 Angstroms shorter for M = U than for M Ce, while the ionic radius of uranium(III) is 0.02 Angstroms larger than that of cerium(III). (authors)

Synthesis and Catalytic Activity of [Cp′Co(COD)] Complexes Bearing Pendant N-Containing Groups

Czech Academy of Sciences Publication Activity Database

Thiel, I.; Lamač, Martin; Jiao, H.; Spannenberg, A.; Hapke, M.

2013-01-01

Roč. 32, č. 11 (2013), s. 3415-3418 ISSN 0276-7333 R&D Projects: GA ČR GPP207/10/P200 Institutional support: RVO:61388955 Keywords : FUNCTIONALIZED CYCLOPENTADIENYL LIGANDS * SANDWICH COBALT COMPLEXES * METALLOCENE COMPLEXES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.253, year: 2013

Iron-titanium-mischmetal alloys for hydrogen storage

Science.gov (United States)

Sandrock, Gary Dale

1978-01-01

A method for the preparation of an iron-titanium-mischmetal alloy which is used for the storage of hydrogen. The alloy is prepared by air-melting an iron charge in a clay-graphite crucible, adding titanium and deoxidizing with mischmetal. The resultant alloy contains less than about 0.1% oxygen and exhibits a capability for hydrogen sorption in less than half the time required by vacuum-melted, iron-titanium alloys.

The coordination and atom transfer chemistry of titanium porphyrin complexes

Energy Technology Data Exchange (ETDEWEB)

Hays, James Allen [Iowa State Univ., Ames, IA (United States)

1993-11-05

Preparation, characterization, and reactivity of (η²- alkyne)(meso-tetratolylpoprphrinato)titanium(II) complexes are described, along with inetermetal oxygen atom transfer reactions involving Ti(IV) and Ti(III) porphyrin complexes. The η²- alkyne complexes are prepared by reaction of (TTP)TiCl₂ with LiAlH₄ in presence of alkyne. Structure of (OEP)Ti(η²-Ph-C≡C-Ph) (OEP=octaethylporphryin) was determined by XRD. The compounds undergo simple substitution to displace the alkyne and produce doubly substituted complexes. Structure of (TTP)Ti(4-picoline)₂ was also determined by XRD. Reaction of (TTP)Ti=O with (OEP)Ti-Cl yields intermetal O/Cl exchange, which is a one-electron redox process mediated by O atom transfer. Also a zero-electron redox process mediated by atom transfer is observed when (TTP)TiCl₂ is reacted with (OEP)Ti=O.

Synthesis, Characterization and Application of A Novel Carbon Bridged Half-metallocene Chromium Catalyst for Methyl Methacrylate Polymerization

Institute of Scientific and Technical Information of China (English)

CHENG Zhengzai; GONG Kai; WANG Yang; ZHOU Xue; ZHANG Weixing; LI Yin; SUN Junquan; LI Wenbing

2014-01-01

A new carbon bridged cyclopentadienyl chromium complex of the type [(C5H4)C(CH3)2 CH2(C5H4N)]CrCl2 was prepared by treatment of CrCl3•(THF)3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis(EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al(i-Bu)3, the chromium complex displayed a very high activity for methyl methacrylate (MMA) polymerization. After 24 hours,more than 95.5%MMA was converted to polymethyl methacrylate (PMMA) with a viscosity average molecular weight (Wη) of 416000 g•mol-1 at 60℃for MMA/Al(i-Bu)3/chromium catalyst molar ratio of up to 2000:20:1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

Group 4 Metal Complexes of Chelating Cyclopentadienyl-ketimide Ligands

Czech Academy of Sciences Publication Activity Database

Večeřa, M.; Varga, Vojtěch; Císařová, I.; Pinkas, Jiří; Kucharczyk, P.; Sedlařík, V.; Lamač, Martin

2016-01-01

Roč. 35, č. 5 (2016), s. 785-798 ISSN 0276-7333 R&D Projects: GA ČR(CZ) GA14-08531S; GA MŠk(CZ) LO1504 Institutional support: RVO:61388955 Keywords : group 4 metal complexes * cyclopentadienyl-ketimide ligands * metallocenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.862, year: 2016

[Experimental study on the corrosion behavior of a type of oral near β-type titanium alloys modified with double glow plasma nitriding].

Science.gov (United States)

Wen, Ke; Li, Fenglan

2015-12-01

To study the electrochemical corrosion performance of a type of biomedical materials near beta titanium alloy(Ti-3Zr-2Sn-3Mo-25Nb, TLM) in artificial saliva before and after nitride changing, and to provide clinical basis for clinical application of titanium alloy TLM. The double glow plasma alloying technology was used to nitride the surface of titanium alloy TLM. The surface properties of the modified layer were observed and tested by optical microscope, scanning electron microscope, glow discharge spectrum analyzer, X-ray diffraction and micro hardness tester. Then, electrochemical measurement system was used to test and compare titanium alloy TLM's electrochemical corrosion in artificial saliva before and after its surface change. Finally, the surface morphology of the original titanium alloy and the modified layer was compared by scanning electron microscope. By the technology of double glow plasma nitriding, the surface of the titanium alloy TLM had been successfully nitrided with a modified layer of 4-5 µm in thickness, uniform and compact. Its main compositions were Ti and Ti(2)N. The Microhardness of modified layer also had been improved from (236.8 ± 5.4) to (871.8 ± 5.2) HV. The self-corrosion potential in electrochemical corrosion tests had been increased from -0.559 V to -0.540 V, while the self- corrosion current density had been reduced from 2.091 × 10(-7) A/cm(2) to 7.188 × 10(-8) A/cm(2). Besides, alternating-current impedance(AC Impedance) had also been increased. With the scanning electron microscope, it's obvious that the diameter of corrosion holes on modified layer were approximately 10 µm. As to the diameter and number of corrosion holes on modified layer, they had been decreased comparing with the original titanium alloy. The type of near beta titanium alloy TLM can construct a nitriding modified layer on its surface. Meanwhile, the performance of its anti- corrosion in artificial saliva has been improved, comparing to the original

Early-transition-metal ketenimine complexes : Synthesis, reactivity, and structure of ketenimine-containing titanocene and zirconocene complexes

NARCIS (Netherlands)

Fandos, R; Lanfranchi, M; Otero, A; Pellinghelli, MA; Ruiz, MJ; Teuben, JH

1997-01-01

Reaction of Cp2M(PMe3)(2) complexes (M = Ti, Zr; Cp = eta(5)-C5H5) with the N-(p-tolyl)-diphenylketenimine Ph'N=C=CPh2 (Ph' = p-MeC6H4) in a 1:1 molar ratio affords the ketenimine-containing metallocene derivatives Cp2M(eta(2)-(C,N)-Ph'N=C=CPh2)(PMe3) (M = Ti (1); Zr (2)). The ketenimine ligand

Desorption of protium and deuterium from different types of titanium beds

International Nuclear Information System (INIS)

Ionete, Eusebiu Ilarian; Dylst, Kris; Gheorghe, Costeanu Claudiu; Stefan, Spiridon Ionut; Florian, Monea Bogdan; Broeckx, Wouter

2017-01-01

When the long term tritium storage is intended, metal hydride materials, particularly the titanium (Ti) beds, seems to be the recommended option, due to its compliance with the criteria of selection (e.g. material cost, stability, storage capacity, loading and unloading conditions, or radioactivity). However few experimental and numerical analyses have been published so far to better support the understanding of the recovery capabilities for different forms of titanium beds. In this work, an investigation on the recovery of different hydrogen isotopes from two types of titanium (Ti) beds, namely Ti powder and Ti sponge, has been performed. Hydrogen isotope release was experimentally verified up to a temperature of 600 °C for both Ti powder and Ti sponge beds. The desorption percentages were determined to be from 24.98 to 20.54 in the case of D_2 on Ti sponge, and from 34.36 to 29.77 in the case of H_2 on Ti sponge. The paper describes in detail the experimental set up, the measurements and the drawn conclusions.

Desorption of protium and deuterium from different types of titanium beds

Energy Technology Data Exchange (ETDEWEB)

Ionete, Eusebiu Ilarian, E-mail: eusebiu.ionete@icsi.ro [National Research and Development Institute for Cryogenics and Isotopic Technologies—ICSI Rm. Valcea, 240050 Ramnicu Valcea (Romania); Dylst, Kris [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Gheorghe, Costeanu Claudiu; Stefan, Spiridon Ionut; Florian, Monea Bogdan [National Research and Development Institute for Cryogenics and Isotopic Technologies—ICSI Rm. Valcea, 240050 Ramnicu Valcea (Romania); Broeckx, Wouter [SCK-CEN, Boeretang 200, 2400 Mol (Belgium)

2017-03-15

When the long term tritium storage is intended, metal hydride materials, particularly the titanium (Ti) beds, seems to be the recommended option, due to its compliance with the criteria of selection (e.g. material cost, stability, storage capacity, loading and unloading conditions, or radioactivity). However few experimental and numerical analyses have been published so far to better support the understanding of the recovery capabilities for different forms of titanium beds. In this work, an investigation on the recovery of different hydrogen isotopes from two types of titanium (Ti) beds, namely Ti powder and Ti sponge, has been performed. Hydrogen isotope release was experimentally verified up to a temperature of 600 °C for both Ti powder and Ti sponge beds. The desorption percentages were determined to be from 24.98 to 20.54 in the case of D{sub 2} on Ti sponge, and from 34.36 to 29.77 in the case of H{sub 2} on Ti sponge. The paper describes in detail the experimental set up, the measurements and the drawn conclusions.

Theoretical study of the structure and reactivity of lanthanide and actinide based organometallic complexes; Etude theorique de la structure et de la reactivite de complexes organometalliques de lanthanides et d'actinides

Energy Technology Data Exchange (ETDEWEB)

Barros, N

2007-06-15

In this PhD thesis, lanthanide and actinide based organometallic complexes are studied using quantum chemistry methods. In a first part, the catalytic properties of organo-lanthanide compounds are evaluated by studying two types of reactions: the catalytic hydro-functionalization of olefins and the polymerisation of polar monomers. The reaction mechanisms are theoretically determined and validated, and the influence of possible secondary non productive reactions is envisaged. A second part focuses on uranium-based complexes. Firstly, the electronic structure of uranium metallocenes is analysed. An analogy with the uranyl compounds is proposed. In a second chapter, two isoelectronic complexes of uranium IV are studied. After validating the use of DFT methods for describing the electronic structure and the reactivity of these compounds, it is shown that their reactivity difference can be related to a different nature of chemical bonding in these complexes. (author)

Theoretical study of the structure and reactivity of lanthanide and actinide based organometallic complexes

International Nuclear Information System (INIS)

Barros, N.

2007-06-01

In this PhD thesis, lanthanide and actinide based organometallic complexes are studied using quantum chemistry methods. In a first part, the catalytic properties of organo-lanthanide compounds are evaluated by studying two types of reactions: the catalytic hydro-functionalization of olefins and the polymerisation of polar monomers. The reaction mechanisms are theoretically determined and validated, and the influence of possible secondary non productive reactions is envisaged. A second part focuses on uranium-based complexes. Firstly, the electronic structure of uranium metallocenes is analysed. An analogy with the uranyl compounds is proposed. In a second chapter, two isoelectronic complexes of uranium IV are studied. After validating the use of DFT methods for describing the electronic structure and the reactivity of these compounds, it is shown that their reactivity difference can be related to a different nature of chemical bonding in these complexes. (author)

[Complex skull defects reconstruction with САD/САМ titanium and polyetheretherketone (PEEK) implants].

Science.gov (United States)

Eolchiyan, S A

2014-01-01

Predictable and stable functional and aesthetic result is the aim of priority for the neurosurgeon dealing with the reconstruction of large cranial bone defects and complex-formed skull defects involving cranio-orbital region. the paper presents the experience with САD/САМ titanium and polyetheretherketone (PEEK) implants for complex-formed and large skull bone defects reconstruction. Between 2005 and 2013 nine patients (5 females and 4 males) underwent cranioplasty and cranio-facial reconstruction with insertion of the customized САD/САМ titanium and PEEK implants. Computer-assisted preoperative planning was undertaken by the surgeon and the engineer together in 3 cases to provide accurate implant design. Eight patients had complex-formed and large posttraumatic defects of fronto-orbital (7 cases) and parietal (one case) regions. In two of these cases one-step reconstruction surgery for posttraumatic fronto-orbital defects combined with adjacent orbital roof (one case) and orbito-zygomatic (one case) deformities was performed. One patient underwent one-step primary cranioplasty after cranio-orbital fibrous dysplasia focus resection. Titanium implants were used in 4 cases while PEEK implants - in 5 ones. The follow-up period ranged from 6 months till 8,5 years (median 4,4 years). The accuracy of the implant intraoperative fit was perfect in all cases. Postoperative wounds healed primary and there were no any complications in the series presented. Post-op clinical assessment and CT data testified to high implants precision, good functional and aesthetic outcomes in all patients. САD/САМ titanium and PEEK implants application should allow for optimal reconstruction in the challenging patients with complex-formed and large skull bone defects providing predictable good functional and aesthetic result together with surgery morbidity and duration reduction. Computer-assisted preoperative planning should be undertaken for САD/САМ implants creation in

On the use of titanium hydride for powder injection moulding of titanium-based alloys

International Nuclear Information System (INIS)

Carrenoo-Morelli, E.; Bidaux, J.-E.

2009-01-01

Full text: Titanium and titanium-based alloys are excellent materials for a number of engineering applications because of their high strength, lightweight, good corrosion resistance, non magnetic characteristic and biocompatibility. The current processing steps are usually costly, and there is a growing demand for net-shape solutions for manufacturing parts of increasing complexity. Powder injection moulding is becoming a competitive alternative, thanks to the advances in production of good quality base-powders, binders and sintering facilities. Titanium hydride powders, have the attractiveness of being less reactive than fine titanium powders, easier to handle, and cheaper. This paper summarizes recent advances on PIM of titanium and titanium alloys from TiH2 powders, including shape-memory NiTi alloys. (author)

Aqueous Synthesis of Technetium-Doped Titanium Dioxide by Direct Oxidation of Titanium Powder, a Precursor for Ceramic Nuclear Waste Forms

Energy Technology Data Exchange (ETDEWEB)

Lukens, Wayne W. [Chemical; Saslow, Sarah A. [Earth

2017-11-17

Technetium-99 (Tc) is a problematic fission product that complicates the long-term disposal of nuclear waste due to its long half-life, high fission yield, and the environmental mobility of pertechnetate, its stable form in aerobic environments. One approach to preventing Tc contamination is through incorporation into durable waste forms based on weathering-resistant minerals such as rutile (titanium dioxide). Here, the incorporation of technetium into titanium dioxide by means of simple, aqueous chemistry is presented. X-ray absorption fine structure spectroscopy and diffuse reflectance spectroscopy indicate that Tc(IV) replaces Ti(IV) within the structure. Rather than being incorporated as isolated Tc(IV) ions, Tc is present as pairs of edge-sharing Tc(IV) octahedra similar to molecular Tc(IV) complexes such as [(H2EDTA)TcIV](u-O)2. Technetium-doped TiO2 was suspended in deionized water under aerobic conditions, and the Tc leached under these conditions was followed for 8 months. The normalized release rate of Tc (LRTc) from the TiO2 particles is low (3×10-6 g m-2 d-1), which illustrates the potential utility of TiO2 as waste form. However, the small size of the as-prepared TiO2 nanoparticles results in estimated retention of Tc for 104 years, which is only a fraction of the half-life of Tc (2×10-5 years).

Long-term Evaluation of Type 2 Thyroplasty with Titanium Bridges for Adductor Spasmodic Dysphonia.

Science.gov (United States)

Sanuki, Tetsuji; Yumoto, Eiji

2017-07-01

Objectives Standard treatments of adductor spasmodic dysphonia (AdSD) provide temporary relief of symptoms. Type 2 thyroplasty offers a long-term solution; however, long-term voice outcome data are lacking. The objective of this study was to assess the long-term voice outcomes of type 2 thyroplasty with titanium bridges through use of a validated voice questionnaire. Study Design Case series with chart review. Setting University hospital. Subjects and Methods Forty-seven consecutively enrolled patients with AdSD underwent type 2 thyroplasty with titanium bridges between August 2006 and November 2014. Questionnaires were completed during regularly scheduled follow-ups and, in some cases, were sent to patients who missed follow-up appointments. In 2015, questionnaires were mailed to all 47 patients and included a Voice Handicap Index-10 evaluation, as well as questions on postoperative vocal symptoms, surgical site, and status of the implanted titanium bridges. Results Of 47 patients with AdSD, 31 (66%) completed the questionnaires. The average follow-up interval was 41.3 months. No patient reported experiencing an adverse event around the surgical site, and almost all were satisfied with their voices postoperatively. The mean postoperative (>3 years) Voice Handicap Index-10 score improved significantly, from 26.3 to 9.4 (n = 17, P = .0009). Conclusions Type 2 thyroplasty for AdSD significantly improved patient quality of life and voice symptoms and continued to do so long after the surgery. The results of this study suggest that type 2 thyroplasty provides relief from vocal symptoms in patients with AdSD for >3 years.

Titanium. Properties, raw datum surface, physicochemical basis and fabrication technique

International Nuclear Information System (INIS)

Garmata, V.A.; Petrun'ko, A.N.; Galitskij, N.V.; Olesov, Yu.G.; Sandler, R.A.

1983-01-01

On the nowadays science and technology achievements the complex of titanium metallurgy problems comprising raw material base, physico-chemical basis and fabrication technique, properties and titanium usage fields is considered for the first time. A particular attention is given to raw material base, manufacturing titanium concentrates and titanium tetrachloride, metallothermal reduction, improvement of metal quality. Data on titanium properties are given, processes of titanium powder metallurgy, scrap and waste processing, problems of economics and complex raw material use are considered

Preparation of ethylene/1-hexene copolymers from ethylene using a fully silica-supported tandem catalyst system

NARCIS (Netherlands)

Karbach, Fabian F.; Macko, Tibor; Duchateau, Robbert

2016-01-01

A silica-supported tandem catalyst system, capable of producing ethylene/1-hexene copolymers from ethylene being the single monomer, has been investigated. As tandem couple a phenoxyimine titanium catalyst for ethylene trimerization was combined with a metallocene catalyst for α-olefin

Uranium fluorides analysis. Titanium spectrophotometric determination

International Nuclear Information System (INIS)

Anon.

Titanium determination in uranium hexafluoride in the range 0.7 to 100 microgrammes after transformation of uranium fluoride in sulfate. Titanium is separated by extraction with N-benzoylphenylhydroxylamine, reextracted by hydrochloric-hydrofluoric acid. The complex titanium-N-benzoylphenylhydroxylamine is extracted by chloroform. Spectrophotometric determination at 400 nm [fr

Room temperature synthesis of protonated layered titanate sheets using peroxo titanium carbonate complex solution.

Science.gov (United States)

Sutradhar, Narottam; Sinhamahapatra, Apurba; Pahari, Sandip Kumar; Bajaj, Hari C; Panda, Asit Baran

2011-07-21

We report the synthesis of peroxo titanium carbonate complex solution as a novel water-soluble precursor for the direct synthesis of layered protonated titanate at room temperature. The synthesized titanates showed excellent removal capacity for Pb(2+) and methylene blue. Based on experimental observations, a probable mechanism for the formation of protonated layered dititanate sheets is also discussed.

Preparation of “Constrained Geometry” Titanium Complexes of [1,2]Azasilinane Framework for Ethylene/1-Octene Copolymerization

Directory of Open Access Journals (Sweden)

Seul Lee

2017-02-01

Full Text Available The Me2Si-bridged ansa-Cp/amido half-metallocene, [Me2Si(η5-Me4C5(NtBu]TiCl2, termed a “constrained-geometry catalyst (CGC”, is a representative homogeneous Ziegler catalyst. CGC derivatives with the [1,2]azasilinane framework, in which the amide alkyl substituent is joined by the Si-bridge, were prepared, and the catalytic performances of these species was studied. Me4C5HSi(Me(CH2CH=CH2-NH(C(R(R’CH=CH2 (R, R’ = H or methyl; Me4C5H = tetramethylcyclopentadienyl was susceptible to ring closure metathesis (RCM when treated with Schrock’s Mo-catalyst to afford -Si(Me4C5H(MeCH2CH=CHC(R(R’NH- containing a six-membered ring framework. Using the precursors and the products of RCM, various CGC derivatives, i.e., [-Si(η5-Me4C5(MeCH2CH=CHC(R(HN-]TiMe2 (13, R = H; 15, R = Me, [-Si(η5-Me4C5(MeCH2CH2CH2CH2N]TiMe2 (14, [(η5-Me4C5Si(Me(CH2CH=CH2NCH2CH=CH2]TiMe2 (16, [(η5-Me4C5Si (Me(CH=CH2NCH2CH=CH2]TiMe2 (17, and [(η5-Me4C5Si(Me(CH2CH3NCH2CH2CH3]TiMe2 (18, were prepared. The catalytic activity of the newly prepared complexes was lower than that of CGC when activated with [Ph3C][B(C6F54]/iBu3Al. However, the catalytic activity of these species was improved by using tetrabutylaluminoxane ([iBu2Al]2O instead of iBu3Al and the activity of 14/[Ph3C][B(C6F54]/[iBu2Al]2O was comparable to that of CGC/[Ph3C][B(C6F54]/iBu3Al (4.7 and 5.0 × 106 g/mol-Ti, respectively. Advantageously, the newly prepared complexes produced higher molecular weight poly(ethylene-co-1-octenes than CGC.

Preparation and crystal structures of low-valent zirconocene complexes containing tetramethyl(phenyl) cyclopentadienyl ligands

Czech Academy of Sciences Publication Activity Database

Horáček, Michal; Pinkas, Jiří; Kubišta, Jiří; Císařová, I.; Gyepes, R.; Štěpnička, P.

2007-01-01

Roč. 72, 5-6 (2007), s. 679-696 ISSN 0010-0765 R&D Projects: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : metallocenes * zirconocenes * bis(trimethylsilyl)acetylene * low-valent zirconium complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.879, year: 2007

The complex sine-Gordon model on a half line

International Nuclear Information System (INIS)

Tzamtzis, Georgios

2003-01-01

In this thesis, we study the complex sine-Gordon model on a half line. The model in the bulk is an integrable (1+1) dimensional field theory which is U(1) gauge invariant and comprises a generalisation of the sine-Gordon theory. It accepts soliton and breather solutions. By introducing suitably selected boundary conditions we may consider the model on a half line. Through such conditions the model can be shown to remain integrable and various aspects of the boundary theory can be examined. The first chapter serves as a brief introduction to some basic concepts of integrability and soliton solutions. As an example of an integrable system with soliton solutions, the sine-Gordon model is presented both in the bulk and on a half line. These results will serve as a useful guide for the model at hand. The introduction finishes with a brief overview of the two methods that will be used on the fourth chapter in order to obtain the quantum spectrum of the boundary complex sine-Gordon model. In the second chapter the model is properly introduced along with a brief literature review. Different realisations of the model and their connexions are discussed. The vacuum of the theory is investigated. Soliton solutions are given and a discussion on the existence of breathers follows. Finally the collapse of breather solutions to single solitons is demonstrated and the chapter concludes with a different approach to the breather problem. In the third chapter, we construct the lowest conserved currents and through them we find suitable boundary conditions that allow for their conservation in the presence of a boundary. The boundary term is added to the Lagrangian and the vacuum is reexamined in the half line case. The reflection process of solitons from the boundary is studied and the time-delay is calculated. Finally we address the existence of boundary-bound states. In the fourth chapter we study the quantum complex sine-Gordon model. We begin with a brief overview of the theory in

Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

Science.gov (United States)

Jarupatrakorn, Jonggol; Don Tilley, T

2002-07-17

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

Synthesis and studies of novel high metal content organic aerogels obtained from a polymerizable titanium complex

International Nuclear Information System (INIS)

Cadra, S.

2010-01-01

Inertial Confinement Fusion (ICF) is a technique widely studied by the French atomic commission (CEA). Experiments will be performed within the Laser Megajoule (LMJ). They require innovative materials like organic aerogels that constitute laser targets. Such polymeric material must provide both a high porosity and a significant titanium percentage (1 atom %). Moreover, the monomers developed must be compatible with the synthesis procedure already in use. According to these specifications, a new polymerizable titanium complex was synthesized and fully characterized. This air and moisture-stable monomer provides a high metal percentage. Its free-radical cross-linked copolymerization affords several titanium-containing polymers. These gels were dried under supercritical conditions and organic aerogels were obtained. The chemical compositions of these materials were investigated by NMR, IR and elemental analysis while their structure was characterized by MEB-EDS, MET, N 2 adsorption/desorption isotherms measurements and SAXS. The data collected fit the specification requirements. Moreover, the mechanisms responsible of the foam nano-structure formation were discussed. (author) [fr

Vanadium and titanium determination by resorcinalhydrazide of salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Karpova, O I; Pilipenko, A T; Lukachina, V V [AN Ukrainskoj SSR, Kiev. Inst. Kolloidnoj Khimii i Khimii Vody

1979-02-01

The complexing of titanium and vanadium with resorcinalhydrazyl of salicylic acid (RHSA) in water-organic media is studied. Titanium (4) forms a complex at pH 0.8-1.8, vanadium - at pH 2.5-5.6, and at pH 7.6-9.8. The complexes are well extracted by polar and nonpolar solvents from acid solutions. The techniques are developed for the determination of titanium and vanadium by the RHSA agent in nickel alloys.

Differential cytotoxicity induced by the Titanium(IV)Salan complex Tc52 in G2-phase independent of DNA damage

International Nuclear Information System (INIS)

Pesch, Theresa; Schuhwerk, Harald; Wyrsch, Philippe; Immel, Timo; Dirks, Wilhelm; Bürkle, Alexander; Huhn, Thomas; Beneke, Sascha

2016-01-01

Chemotherapy is one of the major treatment modalities for cancer. Metal-based compounds such as derivatives of cisplatin are in the front line of therapy against a subset of cancers, but their use is restricted by severe side-effects and the induction of resistance in treated tumors. Subsequent research focused on development of cytotoxic metal-complexes without cross-resistance to cisplatin and reduced side-effects. This led to the discovery of first-generation titanium(IV)salan complexes, which reached clinical trials but lacked efficacy. New-generation titanium (IV)salan-complexes show promising anti-tumor activity in mice, but their molecular mechanism of cytotoxicity is completely unknown. Four different human cell lines were analyzed in their responses to a toxic (Tc52) and a structurally highly related but non-toxic (Tc53) titanium(IV)salan complex. Viability assays were used to reveal a suitable treatment range, flow-cytometry analysis was performed to monitor the impact of dosage and treatment time on cell-cycle distribution and cell death. Potential DNA strand break induction and crosslinking was investigated by immunostaining of damage markers as well as automated fluorometric analysis of DNA unwinding. Changes in nuclear morphology were analyzed by DAPI staining. Acidic beta-galactosidase activity together with morphological changes was monitored to detect cellular senescence. Western blotting was used to analyze induction of pro-apoptotic markers such as activated caspase7 and cleavage of PARP1, and general stress kinase p38. Here we show that the titanium(IV)salan Tc52 is effective in inducing cell death in the lower micromolar range. Surprisingly, Tc52 does not target DNA contrary to expectations deduced from the reported activity of other titanium complexes. Instead, Tc52 application interferes with progression from G2-phase into mitosis and induces apoptotic cell death in tested tumor cells. Contrarily, human fibroblasts undergo senescence in a

Manufacture of a four-sheet complex component from different titanium alloys by superplastic forming

Science.gov (United States)

Allazadeh, M. R.; Zuelli, N.

2017-10-01

A superplastic forming (SPF) technology process was deployed to form a complex component with eight-pocket from a four-sheet sandwich panel sheetstock. Six sheetstock packs were composed of two core sheets made of Ti-6Al-4V or Ti-5Al-4Cr-4Mo-2Sn-2Zr titanium alloy and two skin sheets made of Ti-6Al-4V or Ti-6Al-2Sn-4Zr-2Mo titanium alloy in three different combinations. The sheets were welded with two subsequent welding patterns over the core and skin sheets to meet the required component's details. The applied welding methods were intermittent and continuous resistance seam welding for bonding the core sheets to each other and the skin sheets over the core panel, respectively. The final component configuration was predicted based on the die drawings and finite element method (FEM) simulations for the sandwich panels. An SPF system set-up with two inlet gas pipe feeding facilitated the trials to deliver two pressure-time load cycles acting simultaneously which were extracted from FEM analysis for specific forming temperature and strain rate. The SPF pressure-time cycles were optimized via GOM scanning and visually inspecting some sections of the packs in order to assess the levels of core panel formation during the inflation process of the sheetstock. Two sets of GOM scan results were compared via GOM software to inspect the surface and internal features of the inflated multisheet packs. The results highlighted the capability of the tested SPF process to form complex components from a flat multisheet pack made of different titanium alloys.

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

KAUST Repository

Adamu, Sagir

2015-11-28

This study reports a novel conceptual framework that can be easily experimented to evaluate the effects of hydrodynamic boundary layer mass transfer, methylaluminoxane (MAO) anion design, and comonomer steric hindrance on metallocene-catalyzed ethylene polymerization. This approach was illustrated by conducting homo- and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride (nBuCp)2ZrCl2, using (i) MAO anion 1 (unsupported [MAOCl2]−) and pseudo-homogeneous reference polymerization, and (ii) MAO anion 2 (supported Si−O−[MAOCl2]−) and in-situ heterogeneous polymerization. The measured polymer morphology, catalyst productivity, molecular weight distribution, and inter-chain composition distribution were related to the locus of polymerization, comonomer effect, in-situ chain transfer process, and micromixing effect, respectively. The peak melting and crystallization temperatures and %crystallinity were mathematically correlated to the parameters of microstructural composition distributions, melt fractionation temperatures, and average lamellar thickness. These relations showed to be insightful. The comonomer-induced enchainment defects and the eventual partial disruption of the crystal lattice were successfully modeled using Flory and Gibbs–Thompson equations. The present methodology can also be applied to study ethylene−α-olefin copolymerization, performed using MAO-activated non-metallocene precatalysts.

Physical properties of metallocenes propene-higher α-olefins copolymers

International Nuclear Information System (INIS)

Lovisi, Humberto; Santa Maria, Luiz Claudio de; Coutinho, Fernanda M.B.

2001-01-01

In this work, new copolymers of propene/1-hexene (PHC) and propene/1-octene (POC) were synthesized by using a highly iso specific metallocenes catalyst system based on rac-Me 2 Si(2-ethyl,4-phenyl,1-indenyl) 2 ZrCl 2 , in the homogeneous and heterogeneous forms, methylaluminoxane (MAO) activated. An investigation about the copolymerization of propene with 1-hexene and 1-octene using this catalyst system illustrates the potential for the tailoring of propene/higher α-olefin copolymers with controlled thermal and mechanical properties by varying the comonomer concentration in the polymerization feed. Both catalyst systems showed high activity and produced random copolymers with very low or no detectable crystallinity. It was observed that properties such as enthalpy of crystallization (ΔHc), crystallization temperature (Tc), melting temperature (Tm), glass transition temperature (Tg) and elastic modulus (E') decreased in a linear pattern with increasing comonomer content in the copolymer. The effect of the short chain branch length was also investigated and it was observed that, compared to 1-hexene, much less 1-octene was necessary to disrupt the crystalline structure and impart rubbery behaviour to the copolymers. (author)

Half-Lantern Pt(II and Pt(III Complexes. New Cyclometalated Platinum Derivatives

Directory of Open Access Journals (Sweden)

Violeta Sicilia

2014-08-01

Full Text Available The divalent complex [{Pt(bzq(μ-L}2] (1 [Hbzq = benzo[h]quinolone, HL = CF3C4H2N2SH: 4-(trifluoromethylpyrimidine-2-thiol] was obtained from equimolar amounts of [Pt(bzq(NCMe2]ClO4 and 4-(trifluoromethylpyrimidine-2-thiol with an excess of NEt3. The presence of a low intensity absorption band at 486 nm (CH2Cl2, assignable to a metal-metal-to-ligand charge transfer transition (1MMLCT [dσ*(Pt2→π*(bzq], is indicative of the existence of two platinum centers located in close proximity because the rigidity of the half-lantern structure allows the preservation of these interactions in solution. Compound 1 undergoes two-electron oxidation upon treatment with halogens X2 (X2: Cl2, Br2 or I2 to give the corresponding dihalodiplatinum (III complexes [{Pt(bzq(μ-LX}2] (L = CF3C4H2N2S-κN,S; X: Cl 2, Br 3, I 4. Complexes 2–4 were also obtained by reaction of 1 with HX (molar ratio 1:2, 10% excess of HX in THF with yields of about 80% and compound 2 was also obtained by reaction of [{Pt(bzq(μ-Cl}2] with HL (4-(trifluoromethylpyrimidine-2-thiol in molar ratio 1:2 in THF, although in small yield. The X-ray structures of 2 and 3 confirmed the half-lantern structure and the anti configuration of the molecules. Both of them show Pt–Pt distances (2.61188(15 Å 2, 2.61767(16 Å 3 in the low range of those observed in Pt2(III,IIIX2 half-lantern complexes.

Strength of titanium intramedullary implant versus miniplate fixation of mandibular condyle fractures.

Science.gov (United States)

Frake, Paul C; Howell, Rebecca J; Joshi, Arjun S

2012-07-01

To test the strength of internal fixation of mandibular condyle fractures repaired with titanium miniplates versus titanium intramedullary implants. Prospective laboratory experimentation in urethane mandible models and human cadaveric mandibles. Materials testing laboratory at an academic medical center. Osteotomies of the mandibular condyle were created in 40 urethane hemimandible models and 24 human cadaveric specimens. Half of the samples in each group were repaired with traditional miniplates, and the other half were repaired with intramedullary titanium implants. Anteroposterior and mediolateral loads were applied to the samples, and the displacement was measured with reference to the applied force. Titanium intramedullary implants demonstrated statistically significant improved strength and stiffness versus miniplates in the urethane model experimental groups. Despite frequent plastic deformation and mechanical failures of the miniplates, a 1.6-mm-diameter titanium intramedullary pin did not mechanically fail in any of the cases. Intramedullary implantation failures were due to secondary fracture of the adjacent cortical bone or experimental design limitations including rotation of the smooth pin implant. Mechanical implant failures that were encountered with miniplate fixation were not seen with titanium intramedullary implants. These intramedullary implants provide stronger and more rigid fixation of mandibular condyle fractures than miniplates in this in vitro model.

Long-term voice handicap index after type II thyroplasty using titanium bridges for adductor spasmodic dysphonia.

Science.gov (United States)

Sanuki, Tetsuji; Yumoto, Eiji; Kodama, Narihiro; Minoda, Ryosei; Kumai, Yoshihiko

2014-06-01

To determine the long-term functional outcomes of type II thyroplasty using titanium bridges for adductor spasmodic dysphonia (AdSD) by perceptual analysis using the Voice Handicap Index-10 (VHI-10) and by acoustic analysis. Fifteen patients with AdSD underwent type II thyroplasty using titanium brides between August 2006 and February 2011. VHI-10 scores, a patient-based survey that quantifies a patient's perception of his or her vocal handicap, were determined before and at least 2 years after surgery. Concurrent with the VHI-10 evaluation, acoustic parameters were assessed, including jitter, shimmer, harmonic-to-noise ratio (HNR), standard deviation of F0 (SDF0), and degree of voice breaks (DVB). The average follow-up interval was 30.1 months. No patient had strangulation of the voice, and all were satisfied with the voice postoperatively. In the perceptual analysis, the mean VHI-10 score improved significantly, from 26.7 to 4.1 two years after surgery. All patients had significantly improved each score of three different aspects of VHI-10, representing improved functional, physical, and emotional well-being. All acoustic parameters improved significantly 2 years after surgery. The treatment of AdSD with type II thyroplasty significantly improved the voice-related quality of life and acoustic parameters 2 years after surgery. The results of the study suggest that type II thyroplasty using titanium bridges provides long-term relief of vocal symptoms in patients with AdSD. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Titanium fasteners. [for aircraft industry

Science.gov (United States)

Phillips, J. L.

1972-01-01

Titanium fasteners are used in large quantities throughout the aircraft industry. Most of this usage is in aluminum structure; where titanium structure exists, titanium fasteners are logically used as well. Titanium fasteners offer potential weight savings to the designer at a cost of approximately $30 per pound of weight saved. Proper and least cost usage must take into consideration type of fastener per application, galvanic couples and installation characteristics of protective coatings, cosmetic appearance, paint adhesion, installation forces and methods available and fatigue performance required.

Stepwise Ti-Cl, Ti-CH3, and Ti-C6H5 bond dissociation enthalpies in bis(pentamethylcyclopentadienyl)titanium complexes

NARCIS (Netherlands)

Dias, Alberto R.; Salema, Margarida S.; Martinho Simões, Jose A.; Pattiasina, Johannes W.; Teuben, Jan H.

1988-01-01

Reaction-solution calorimetric studies involving the complexes Ti[η5-C5(CH3)5]2(CH3)2, Ti[η5-C5(CH3)5]2(CH3), Ti[η5-C5(CH3)5]2(C6H5), Ti[η5-C5(CH3)5]2Cl2, and Ti[η5-C5(CH3)5]2Cl, have enabled derivation of titanium-carbon and titanium-chlorine stepwise bond dissociation enthalpies in these species.

Sorption rate of uranyl ions by hyphan cellulose exchangers and by hydrated titanium dioxide

International Nuclear Information System (INIS)

Ambe, F.; Burba, P.; Lieser, K.H.

1979-01-01

Sorption of uranyl ions by the cellulose exchanger Hyphan proceeds rather fast. Two steps are observed with half-times of the order of 10 s and 2 min. The majority of the uranyl ions is bound in 1 min. Sorption of uranyl ions by titanium dioxide is a very slow process. For particle sizes between 0,1 and 0,5 mm the half-time is about 3 h and equilibrium is attained in about 1 day. The effect of stirring suspensions of inorganic sorbents like titanium dioxide in solution is investigated in detail. Sorption of uranyl ions by titanium dioxide and change in pH in solution are measured simultaneously as a function of time. (orig.) [de

Naked (C5Me5)(2)M cations (M = Sc, Ti, and V) and their fluoroarene complexes

NARCIS (Netherlands)

Bouwkamp, MW; Budzelaar, PHM; Gercama, J; Morales, ID; de Wolf, J; Meetsma, A; Troyanov, SI; Teuben, JH; Hessen, B; Budzelaar, Peter H.M.; Hierro Morales, Isabel Del; Troyanov, Sergei I.

2005-01-01

The ionic metallocene complexes [Cp*M-2][BPh4] (CP* = C5Me5) of the trivalent 3d metals Sc, Ti, and V were synthesized and structurally characterized. For M Sc, the anion interacts weakly with the metal center through one of the phenyl groups, but for M = Ti and V, the cations are naked. They each

Rough surfaces of titanium and titanium alloys for implants and prostheses

International Nuclear Information System (INIS)

Conforto, E.; Aronsson, B.-O.; Salito, A.; Crestou, C.; Caillard, D.

2004-01-01

Titanium and titanium alloys for dental implants and hip prostheses were surface-treated and/or covered by metallic or ceramic rough layers after being submitted to sand blasting. The goal of these treatments is to improve the surface roughness and consequently the osteointegration, the fixation, and the stability of the implant. The microstructure of titanium and titanium alloys submitted to these treatments has been studied and correlated to their mechanical behavior. As-treated/covered and mechanically tested surfaces were characterized by scanning electron microscopy (SEM). Structural analyses performed by transmission electron microscopy (TEM), mainly in cross-section, reveal the degree of adherence and cohesion between the surface layer and the substrate (implant). We observed that, although the same convenient surface roughness was obtained with the two types of process, many characteristics as structural properties and mechanical behavior are very different

Kinetics of growing the disordered antiphase domains in titanium carbohydride TiC0.50H0.21

International Nuclear Information System (INIS)

Khidirov, I.; Sotvoldiev, D.I.

2010-01-01

For establishing formation and growth laws of the disordered nanostructures (the antiphase domains) in the nonstoichiometric titanium carbohydride with cubic NaCl type structure we quenched the titanium carbohydride TiC 0.50 H 0.21 from 1000 deg C followed by annealing at 500, 600, 700, 800 deg C with 24 hour ageing. Neutron diffraction patterns were recorded after each annealing temperature. The half-width of the superstructure (111) reflection is shown to decrease with increasing the annealing temperature that testified on the disordered nanostructure size growing with temperature. The sizes of the disordered nanostructure formed at various temperatures and their dependence D = f(T) were determined on the basis of the neutron diffraction data. (authors)

Sorption kinetics of cesium on hydrous titanium dioxide

International Nuclear Information System (INIS)

Altas, Y.; Tel, H.; Yaprak, G.

2003-01-01

Two types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs + ion for Type1 and Type2 titanium dioxides at pH 12 were calculated as 2.79 x 10 -11 m 2 s -1 and 1.52 x 10 -11 m 2 s -1 , respectively, under particle diffusion controlled conditions. (orig.)

On the Phase Separation in n-Type Thermoelectric Half-Heusler Materials

Directory of Open Access Journals (Sweden)

Michael Schwall

2018-04-01

Full Text Available Half-Heusler compounds have been in focus as potential materials for thermoelectric energy conversion in the mid-temperature range, e.g., as in automotive or industrial waste heat recovery, for more than ten years now. Because of their mechanical and thermal stability, these compounds are advantageous for common thermoelectric materials such as Bi 2 Te 3 , SiGe, clathrates or filled skutterudites. A further advantage lies in the tunability of Heusler compounds, allowing one to avoid expensive and toxic elements. Half-Heusler compounds usually exhibit a high electrical conductivity σ , resulting in high power factors. The main drawback of half-Heusler compounds is their high lattice thermal conductivity. Here, we present a detailed study of the phase separation in an n-type Heusler materials system, showing that the Ti x Zr y Hf z NiSn system is not a solid solution. We also show that this phase separation is key to the thermoelectric high efficiency of n-type Heusler materials. These results strongly underline the importance of phase separation as a powerful tool for designing highly efficient materials for thermoelectric applications that fulfill the industrial demands of a thermoelectric converter.

Titanium Insertion into CO Bonds in Anionic Ti-CO2 Complexes.

Science.gov (United States)

Dodson, Leah G; Thompson, Michael C; Weber, J Mathias

2018-03-22

We explore the structures of [Ti(CO 2 ) y ] - cluster anions using infrared photodissociation spectroscopy and quantum chemistry calculations. The existence of spectral signatures of metal carbonyl CO stretching modes shows that insertion of titanium atoms into C-O bonds represents an important reaction during the formation of these clusters. In addition to carbonyl groups, the infrared spectra show that the titanium center is coordinated to oxalato, carbonato, and oxo ligands, which form along with the metal carbonyls. The presence of a metal oxalato ligand promotes C-O bond insertion in these systems. These results highlight the affinity of titanium for C-O bond insertion processes.

A novel platelet concentrate: titanium-prepared platelet-rich fibrin.

Science.gov (United States)

Tunalı, Mustafa; Özdemir, Hakan; Küçükodacı, Zafer; Akman, Serhan; Yaprak, Emre; Toker, Hülya; Fıratlı, Erhan

2014-01-01

We developed a new product called titanium-prepared platelet-rich fibrin (T-PRF). The T-PRF method is based on the hypothesis that titanium may be more effective in activating platelets than the silica activators used with glass tubes in Chouckroun's leukocyte- and platelet-rich fibrin (L-PRF) method. In this study, we aimed to define the structural characteristics of T-PRF and compare it with L-PRF. Blood samples were collected from 10 healthy male volunteers. The blood samples were drawn using a syringe. Nine milliliters was transferred to a dry glass tube, and 9 mL was transferred to a titanium tube. Half of each clot (i.e., the blood that was clotted using T-PRF or L-PRF) was processed with a scanning electron microscope (SEM). The other half of each clot was processed for fluorescence microscopy analysis and light microscopy analysis. The T-PRF samples seemed to have a highly organized network with continuous integrity compared to the other L-PRF samples. Histomorphometric analysis showed that T-PRF fibrin network covers larger area than L-PRF fibrin network; also fibrin seemed thicker in the T-PRF samples. This is the first human study to define T-PRF as an autogenous leukocyte- and platelet-rich fibrin product. The platelet activation by titanium seems to offer some high characteristics to T-PRF.

A Novel Platelet Concentrate: Titanium-Prepared Platelet-Rich Fibrin

Directory of Open Access Journals (Sweden)

Mustafa Tunalı

2014-01-01

Full Text Available We developed a new product called titanium-prepared platelet-rich fibrin (T-PRF. The T-PRF method is based on the hypothesis that titanium may be more effective in activating platelets than the silica activators used with glass tubes in Chouckroun’s leukocyte- and platelet-rich fibrin (L-PRF method. In this study, we aimed to define the structural characteristics of T-PRF and compare it with L-PRF. Blood samples were collected from 10 healthy male volunteers. The blood samples were drawn using a syringe. Nine milliliters was transferred to a dry glass tube, and 9 mL was transferred to a titanium tube. Half of each clot (i.e., the blood that was clotted using T-PRF or L-PRF was processed with a scanning electron microscope (SEM. The other half of each clot was processed for fluorescence microscopy analysis and light microscopy analysis. The T-PRF samples seemed to have a highly organized network with continuous integrity compared to the other L-PRF samples. Histomorphometric analysis showed that T-PRF fibrin network covers larger area than L-PRF fibrin network; also fibrin seemed thicker in the T-PRF samples. This is the first human study to define T-PRF as an autogenous leukocyte- and platelet-rich fibrin product. The platelet activation by titanium seems to offer some high characteristics to T-PRF.

Array of titanium dioxide nanostructures for solar energy utilization

Science.gov (United States)

Qiu, Xiaofeng; Parans Paranthaman, Mariappan; Chi, Miaofang; Ivanov, Ilia N; Zhang, Zhenyu

2014-12-30

An array of titanium dioxide nanostructures for solar energy utilization includes a plurality of nanotubes, each nanotube including an outer layer coaxial with an inner layer, where the inner layer comprises p-type titanium dioxide and the outer layer comprises n-type titanium dioxide. An interface between the inner layer and the outer layer defines a p-n junction.

Classification of titanium dioxide

International Nuclear Information System (INIS)

Macias B, L.R.; Garcia C, R.M.; Maya M, M.E.; Ita T, A. De; Palacios G, J.

2002-01-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO 2 . The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

Oscillation and non-oscillation criterion for Riemann–Weber type half-linear differential equations

Directory of Open Access Journals (Sweden)

Petr Hasil

2016-08-01

Full Text Available By the combination of the modified half-linear Prüfer method and the Riccati technique, we study oscillatory properties of half-linear differential equations. Taking into account the transformation theory of half-linear equations and using some known results, we show that the analysed equations in the Riemann–Weber form with perturbations in both terms are conditionally oscillatory. Within the process, we identify the critical oscillation values of their coefficients and, consequently, we decide when the considered equations are oscillatory and when they are non-oscillatory. As a direct corollary of our main result, we solve the so-called critical case for a certain type of half-linear non-perturbed equations.

Titanium coordination compounds: from discrete metal complexes to metal–organic frameworks

KAUST Repository

Assi, Hala

2017-05-24

Owing to their promise in photocatalysis and optoelectronics, titanium based metal–organic frameworks (MOFs) are one of the most appealing classes of MOFs reported to date. Nevertheless, Ti-MOFs are still very scarce because of their challenging synthesis associated with a poor degree of control of their chemistry and crystallization. This review aims at giving an overview of the recent progress in this field focusing on the most relevant existing titanium coordination compounds as well as their promising photoredox properties. Not only Ti-MOFs but also Ti-oxo-clusters will be discussed and particular interest will be dedicated to highlight the different successful synthetic strategies allowing to overcome the still “unpredictable” reactivity of titanium ions, particularly to afford crystalline porous coordination polymers.

The characteristics of corrosion, radiation degradation and dissolution of titanium alloys

International Nuclear Information System (INIS)

Sung, K. W.; Na, J. W.; Choi, B. S.; Lee, D. J.; Chang, M. H.

2001-12-01

In order to establish the technical bases of water chemistry design requirement related titanium alloys, we investigated the characteristics of corrosion, activation, radiation degradation, radiation hydrogen embrittlement of titanium alloys and dissolution of titanium dioxide. Titanium alloys generally have high corrosion resistance. Corrosion product release from PT-7M and PT-3V titanium alloy surface for 18 months of operation is negligible, and the corrosion penetration for about 30 years is about 1 μm, while the corrosion rates is not higher than one third of that of austenitic steel. Titanium only converts into Sc-46 with 85 day halflife after neutron irradiation, and its radioactivity is not higher than one thousandth of that produced from nickel. Therefore, under the condition without any neutron irradiation, the radiation damage of titanium alloys would have no problem. Titanium dioxide, that protects the metals from the corrosion, has retrograde solubility in neutral solutions. It does not form any complexes with ligands such as ammonia, but Ti(IV) gets more stable by complexing with water molecules. In conclusion, it is estimated that titanium alloys such as PT-7M would be applicable to steam generator materials

Synthesis and structure of the first fullerene complex of titanium Cp{sub 2}Ti({eta}{sup 2}-C{sub 60})

Energy Technology Data Exchange (ETDEWEB)

Burlakov, V.V.; Usatov, A.V.; Lyssenko, K.A.; Antipin, M.Yu.; Novikov, Yu.N.; Shur, V.B. [Russian Academy of Sciences, Moscow (Russian Federation). A.N. Nesmeyanov Inst. of Organoelement Compounds

1999-11-01

The first fullerene complex of titanium Cp{sub 2}Ti({eta}{sup 2}-C{sub 60}) has been synthesized by reaction of the bis(trimethylsilyl)-acetylene complex of titanocene Cp{sub 2}Ti({eta}{sup 2}-Me{sub 3}SiC{sub 2}SiMe{sub 3}) with an equimolar amount of fullerene-60 in toluene at room temperature under argon. An X-ray diffraction study of the complex has shown that it has the structure of a titanacyclopropane derivative. (orig.)

Titanium implants in irradiated dog mandibles

International Nuclear Information System (INIS)

Schweiger, J.W.

1989-01-01

The use of osseointegrated titanium implants has been a great benefit to selected cancer patients who otherwise would not be able to wear conventional and/or maxillofacial prostheses. Cognizant of the risk of osteoradionecrosis, we used an animal model to seek experimental evidence for successful osseointegration in bone irradiated to tumoricidal levels. Five healthy male beagle dogs received 60 gray to a previously edentulated and healed area of the right hemimandible. The left hemimandible was kept as a nonirradiated control. After 9 months, titanium implants were placed and allowed an additional 5 1/2 months to osseointegrate. At that time, block specimens were obtained, radiographed, photographed, and analyzed histologically. Although statistical significance cannot be attached to the results, osseointegration was achieved in half of the irradiated specimens

Positron annihilation in hydrogenated and electron-irradiated titanium alloys

International Nuclear Information System (INIS)

Mukashev, K.M.; Zaikin, Yu.A.

2002-01-01

Important information on hydrogen behavior in titanium can be obtained from studies of radiation damage in previously hydrogenated metal. For this purpose annealed titanium samples were hydrogenated at the temperature 500 deg. C during 1 hour. Then both the original annealed samples and hydrogenated samples were irradiated by 4 MeV electrons in the fluence range 3·10 7 -1·10 19 cm - 2 at the temperature 60 deg. C. It is known that electron irradiation in these conditions predominantly creates vacancy-type defects with an average radius R ν =0.81 Angstrom. It was stated that annihilation probability after electron irradiation of previously hydrogenated titanium samples always has some intermediate values between those characteristic for hydrogenated and irradiated states of previously annealed metal. This is a reason to suppose that radiation defects of the vacancy type in previously hydrogenated titanium combine with hydrogen atoms in favorable conditions of their partial ionization. The estimated value of the average radius for such a complex is R ν =1.1 Angstrom, that is higher than vacancy size but lower than an atom radius. No dose dependence of hydrogen interaction with radiation defects was observed in our experiments.The results of isochrone annealing of the materials under study have shown that the single annealing recovery stage with activation energy E a equal to 1.22 eV is observed in electron irradiated but not previously hydrogenated titanium in the temperature range 170-240 deg. C. Electron irradiation of the previously hydrogenated metal shifts beginning of the first recovery stage to the temperature about 225-230 deg. C and finishes near the temperature 330 deg. C. Therefore, the bound state vacancy-hydrogen in titanium is characterized by higher temperature range of dissociation and annealing with activation energy equal to 1.38 eV. However, subsequent measurements, of the angular distribution of annihilation photons (ADAP) have demonstrated

Analysis of titanium content in titanium tetrachloride solution

Science.gov (United States)

Bi, Xiaoguo; Dong, Yingnan; Li, Shanshan; Guan, Duojiao; Wang, Jianyu; Tang, Meiling

2018-03-01

Strontium titanate, barium titan and lead titanate are new type of functional ceramic materials with good prospect, and titanium tetrachloride is a commonly in the production such products. Which excellent electrochemical performance of ferroelectric tempreature coefficient effect.In this article, three methods are used to calibrate the samples of titanium tetrachloride solution by back titration method, replacement titration method and gravimetric analysis method. The results show that the back titration method has many good points, for example, relatively simple operation, easy to judgment the titration end point, better accuracy and precision of analytical results, the relative standard deviation not less than 0.2%. So, it is the ideal of conventional analysis methods in the mass production.

New technique to determine beta half-lives in complex background conditions

International Nuclear Information System (INIS)

Kurtukian-Nieto, T.; Benlliure, J.; Casarejos, E.; Cortina-Gil, D.; Fernandez-Ordonez, M.; Pereira, J.; Schmidt, K.H.; Becker, F.; Henzlova, D.; Yordanov, O.; Audouin, L.; Blank, B.; Giovinazzo, J.; Jurado, B.; Rejmund, F.

2008-01-01

Very neutron-rich nuclei near the A = 195 r-process waiting point were produced as projectile fragments from a 208 Pb primary beam at GSI, Darmstadt, by cold fragmentation. After in-flight separation, the fragments were implanted in an active catcher, and time correlations to the subsequent beta-decay were established. Due to the periodic operation cycles of the synchrotron, providing the primary beam, the background shows a complex time structure, which prevents applying well established analytical methods to extract the half-life information. A new mathematical analysis method has been developed, which is based on a Monte Carlo code, simulating the time sequence of implantation and beta detection according to the experimental conditions, leaving the beta lifetimes and the beta detection efficiency as free parameters. In addition, both the analysis of the experimental data and the simulation were performed in time-reversed sequence. The ratio of forward/backward time spectra contains the information of the 'true' fragment-beta correlations. Half-lives were obtained from two-dimensional fits of the measured and simulated ratios of time correlations in forward- and backward-time direction by the least-squares method, being the lifetime and the beta-detection efficiency the two fitting parameters. Half-lives of 8 heavy neutron-rich nuclei approaching the r-process waiting point A = 195 have been determined. (authors)

Opportunities in the electrowinning of molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available used, the following forms of titanium are produced: titanium sponge, sintered electrode sponge, powder, molten titanium, electroplated titanium, hydride powder, and vapor-phase depos- ited titanium. Comparing the economics of alter- native...-up for producing titanium via the Kroll process is approximately as follows: ilmenite ($0.27/kg titanium sponge); titanium slag ($0.75/kg titanium sponge); TiCl4 ($3.09/kg titanium sponge); titanium sponge raw materials costs ($5.50/kg titanium sponge); total...

Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

KAUST Repository

Baker, L. Robert

2011-08-18

The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

Physical metallurgy of titanium alloys

International Nuclear Information System (INIS)

Collings, E.W.

1988-01-01

Researches in electric, magnetic, thermophysical properties of titanium alloys in the wide range of temperatures (from helium upto elevated one), as well as stability of phases in alloys of different types are generalized. Fundamental description of physical properties of binary model alloys is given. Acoustic emission, shape memory and Bauschinger effects, pseudoelasticity, aging and other aspects of physical metallurgy of titanium alloys are considered

Compressive and fatigue behavior of beta-type titanium porous structures fabricated by electron beam melting

International Nuclear Information System (INIS)

Liu, Y.J.; Wang, H.L.; Li, S.J.; Wang, S.G.; Wang, W.J.; Hou, W.T.; Hao, Y.L.; Yang, R.; Zhang, L.C.

2017-01-01

β-type titanium porous structure is a new class of solution for implant because it offers excellent combinations of high strength and low Young's modulus. This work investigated the influence of porosity variation in electron beam melting (EBM)-produced β-type Ti2448 alloy samples on the mechanical properties including super-elastic property, Young's modulus, compressive strength and fatigue properties. The relationship between the misorientation angle of adjacent grains and fatigue crack deflection behaviors was also observed. The super-elastic property is improved as the porosity of samples increases because of increasing tensile/compressive ratio. For the first time, the position of fatigue crack initiation is defined in stress-strain curves based on the variation of the fatigue cyclic loops. The unique manufacturing process of EBM results in the generation of different sizes of grains, and the apparent fatigue crack deflection occurs at the grain boundaries in the columnar grain zone due to substantial misorientation between adjacent grains. Compared with Ti-6Al-4V samples, the Ti2448 porous samples exhibit a higher normalized fatigue strength owing to super-elastic property, greater plastic zone ahead of the fatigue crack tip and the crack deflection behavior. - Highlights: • The super-elastic property is improved with increasing porosity of Ti2448 porous samples. • The position of fatigue crack initiation on the strain curve is defined. • The unique EBM-produced microstructure leads to apparent fatigue crack deflection occurring at columnar grain boundary. • Ti2448 porous samples display only half of the Young's modulus of Ti-6Al-4V porous samples at same fatigue strength level.

A comparison of fit of CNC-milled titanium and zirconia frameworks to implants.

Science.gov (United States)

Abduo, Jaafar; Lyons, Karl; Waddell, Neil; Bennani, Vincent; Swain, Michael

2012-05-01

Computer numeric controlled (CNC) milling was proven to be predictable method to fabricate accurately fitting implant titanium frameworks. However, no data are available regarding the fit of CNC-milled implant zirconia frameworks. To compare the precision of fit of implant frameworks milled from titanium and zirconia and relate it to peri-implant strain development after framework fixation. A partially edentulous epoxy resin models received two Branemark implants in the areas of the lower left second premolar and second molar. From this model, 10 identical frameworks were fabricated by mean of CNC milling. Half of them were made from titanium and the other half from zirconia. Strain gauges were mounted close to the implants to qualitatively and quantitatively assess strain development as a result of framework fitting. In addition, the fit of the framework implant interface was measured using an optical microscope, when only one screw was tightened (passive fit) and when all screws were tightened (vertical fit). The data was statistically analyzed using the Mann-Whitney test. All frameworks produced measurable amounts of peri-implant strain. The zirconia frameworks produced significantly less strain than titanium. Combining the qualitative and quantitative information indicates that the implants were under vertical displacement rather than horizontal. The vertical fit was similar for zirconia (3.7 µm) and titanium (3.6 µm) frameworks; however, the zirconia frameworks exhibited a significantly finer passive fit (5.5 µm) than titanium frameworks (13.6 µm). CNC milling produced zirconia and titanium frameworks with high accuracy. The difference between the two materials in terms of fit is expected to be of minimal clinical significance. The strain developed around the implants was more related to the framework fit rather than framework material. © 2011 Wiley Periodicals, Inc.

Isothermal deformation of gamma titanium aluminide

International Nuclear Information System (INIS)

Srinivasan, R.; Singh, J.P.; Tuval, E.; Weiss, I.

1996-01-01

Gamma titanium aluminide has received considerable attention in recent years from the automotive industry as a potential material for making rotating and reciprocating components to produce a quieter and more efficient engine. The objectives of this study were to identify processing routes for the manufacture of automobile valves from gamma titanium aluminide. The issues considered were microstructure and composition of the material, and processing parameters such as deformation rates, temperatures, and total deformation. This paper examines isothermal deformation of gamma titanium aluminide in order to develop a processing window for this type of material

High pressure sintering (HP-HT) of diamond powders with titanium and titanium carbide

International Nuclear Information System (INIS)

Jaworska, L.

1999-01-01

Polycrystalline diamond compacts for cutting tools are mostly manufactured using high pressure sintering (HP-HT). The standard diamond compacts are prepared by diamond powders sintering with metallic binding phase. The first group of metallic binder are metals able to solve carbon - Co, Ni. The second group of metal binders are carbide forming elements - Ti, Cr, W and others. The paper describes high pressure sintering of diamond powder with titanium and nonstoichiometry titanium carbide for cutting tool application. A type of binding phase has the significant influence on microstructure and mechanical properties of diamond compacts. Very homogeneous structure was achieved in case of compacts obtained from metalized diamond where diamond-TiC-diamond connection were predominant. In the case of compacts prepared by mechanical mixing of diamond with titanium powders the obtained structure was nonhomogeneous with titanium carbide clusters. They had more diamond to diamond connections. These compacts compared to the compact made of metallized diamond have greater wear resistance. In the case of the diamond and TiC 0.92 sintering the strong bonding of TiC diamond grains was obtained. The microstructure observations for diamond with 5% wt. Ti and diamond with 5% wt. TiC 0.92 (the initial composition) compacts were performed in transmission microscope. For two type of compacts the strong bonding phase TiC without defects is creating. (author)

Electronic Structure Properties and a Bonding Model of Thermoelectric Half-Heusler and Boride Phases

Science.gov (United States)

Simonson, Jack William

Half-Heusler alloys MNiSn and MCoSb (M = Ti, Zr, Hf) and layered boride intermetallics with structure types YCrB4 and Er 3CrB7 were designed, synthesized, and characterized. The thermoelectric properties of these two classes of alloys were measured from room temperature to 1100 K with the intent of indirectly studying their electronic structure properties and gauging not only their suitability but that of related alloys for high temperature thermoelectric power generation. In the case of the half-Heusler alloys, transition metals were substituted to both the M and Ni/Co sites to study the resultant modifications of the d-orbital-rich portion of the electronic structure near the Fermi energy. This modification and subsequent pinning of the Fermi energy within the gap is discussed herein in terms of first principles electronic structure calculations from the literature. In the half-Heusler alloys, it was found that substitution of transition metals invariably led to a decrease in the thermopower, while the resistivity typically maintained its semiconducting trend. On the other hand, Sn doping in MCoSb type alloys -- a dopant that has been known for some time to be efficient -- was shown to result in high ZT at temperatures in excess of 1000 K. Moreover, the band gaps of the transition metal-doped alloys measured in this work offer insight into the discrepancy between the predicted and measured band gaps in the undoped parent compositions. In the case of the layered boride alloys, on the other hand, few electronic calculations have been published, thus prompting the generalization of a well-known electron counting rule -- which is typically used to study molecular organometallics, boranes, and metallocenes -- to predict the trends in the densities of states of crystalline solids that possess the requisite deltahedral bonding geometry. In accordance with these generalized electronic counting rules, alloys of the form RMB4 (R = Y, Gd, Ho; M = Cr, Mo, W) were measured to

Preparation and characterization of hybrid materials of epoxy resin type bisphenol a with silicon and titanium oxides by sol-gel process

International Nuclear Information System (INIS)

Carrillo C, A.; Osuna A, J. G.

2011-01-01

Hybrid materials were synthesized from epoxy resins as a result bisphenol type A-silicon oxide and epoxy resin bisphenol type A-titanium oxide were obtained. The synthesis was done by sol-gel process using tetraethyl orthosilicate (Teos) and titanium isopropoxide (I Ti) as inorganic precursors. The molar ratio of bisphenol A to the inorganic precursors was the studied variable. The materials were characterized by thermal analysis, infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The hybrid nature of the materials was demonstrated through thermal analysis and infrared spectroscopy. In both systems, as the amount of alkoxide increased, the bands described above were more defined. This behavior indicates the interactions between the resin and the alkoxides. Hybrids with Teos showed a smoother and homogeneous surface in its entirety, without irregularities. Hybrids with titanium isopropoxide had low roughness. Both Teos and I Ti hybrids showed a decrease on the atomic weight percentage of carbon due to a slight reduction of the organic part on the surface. (Author)

Preparation and characterization of hybrid materials of epoxy resin type bisphenol a with silicon and titanium oxides by sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Carrillo C, A.; Osuna A, J. G., E-mail: acc.carrillo@gmail.com [Universidad Autonoma de Coahuila, Facultad de Ciencias Quimicas, Blvd. Venustiano Carranza y Jose Cardenas Valdes, 25000 Saltillo, Coahuila (Mexico)

2011-07-01

Hybrid materials were synthesized from epoxy resins as a result bisphenol type A-silicon oxide and epoxy resin bisphenol type A-titanium oxide were obtained. The synthesis was done by sol-gel process using tetraethyl orthosilicate (Teos) and titanium isopropoxide (I Ti) as inorganic precursors. The molar ratio of bisphenol A to the inorganic precursors was the studied variable. The materials were characterized by thermal analysis, infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The hybrid nature of the materials was demonstrated through thermal analysis and infrared spectroscopy. In both systems, as the amount of alkoxide increased, the bands described above were more defined. This behavior indicates the interactions between the resin and the alkoxides. Hybrids with Teos showed a smoother and homogeneous surface in its entirety, without irregularities. Hybrids with titanium isopropoxide had low roughness. Both Teos and I Ti hybrids showed a decrease on the atomic weight percentage of carbon due to a slight reduction of the organic part on the surface. (Author)

Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium

International Nuclear Information System (INIS)

Yatirajam, V.; Arya, S.P.

1975-01-01

A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1 to 2 N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2 to 5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium. (author)

Corrosion of gold alloys and titanium in artificial saliva

International Nuclear Information System (INIS)

Brune, D.; Evje, D.

1982-01-01

Two types of gold alloys and one type of pure titanium have been submitted to corrosion in artificial saliva for periods of up to about 2 months. The release of copper, gold and silver from the gold alloys as well as titanium from the titanium matrix was measured with nuclear tracer technique. The physical/chemical state of the corrosion products of gold alloys referring to the ionic state or presence in particulate form has been examined retaining the particulate matter on a glass filter. Copper was observed to be mainly present in the ionic state. Considerable amounts of gold were observed to be retained on the glass filter explained by the presence of gold in particulate form or as a compentent of a dispersed collloidal phase. The estimation of the release of titanium was registered by the tracer nuclide 46 Sc assuming particulate matter to be deteriorated from the titanium surface. (author)

Titanium-Based Biomaterials for Preventing Stress Shielding between Implant Devices and Bone

Directory of Open Access Journals (Sweden)

M. Niinomi

2011-01-01

Full Text Available β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants.

Corrosion and microstructural aspects of dissimilar joints of titanium and type 304L stainless steel

International Nuclear Information System (INIS)

Mudali, U. Kamachi.; Ananda Rao, B.M.; Shanmugam, K.; Natarajan, R.; Raj, Baldev

2003-01-01

To link titanium and zirconium metal based (Ti, Zr-2, Ti-5%Ta, Ti-5%Ta-1.8Nb) dissolver vessels containing highly radioactive and concentrated corrosive nitric acid solution to other nuclear fuel reprocessing plant components made of AISI type 304L stainless steel (SS), high integrity and corrosion resistant dissimilar joints between them are necessary. Fusion welding processes produce secondary precipitates which dissolve in nitric acid, and hence solid-state processes are proposed. In this work, various dissimilar joining processes available for producing titanium-304L SS joints with adequate strength, ductility and corrosion resistance for this critical application are highlighted. Developmental efforts made at IGCAR, Kalpakkam are outlined. The possible methods and the microstructural-metallurgical properties of the joints along with corrosion results obtained with three phase (liquid, vapour, condensate) corrosion testing are discussed. Based on the results, dissimilar joint produced by the explosive joining process was adopted for plant application

Corrosion resistance of titanium alloys for dentistry

International Nuclear Information System (INIS)

Laskawiec, J.; Michalik, R.

2001-01-01

Titanium and its alloys belong to biomaterials which the application scope in medicine increases. Some properties of the alloys, such as high mechanical strength, low density, low Young's modulus, high corrosion resistance and good biotolerance decide about it. The main areas of the application of titanium and its alloys are: orthopedics and traumatology, cardiosurgery, faciomaxillary surgery and dentistry. The results of investigations concerning the corrosion resistance of the technical titanium and Ti6Al14V alloy and comparatively a cobalt alloy of the Vitallium type in the artificial saliva is presented in the work. Significantly better corrosion resistance of titanium and the Ti6Al14V than the Co-Cr-Mo alloy was found. (author)

In vitro assessment of artifacts induced by titanium, titanium-zirconium and zirconium dioxide implants in cone-beam computed tomography.

Science.gov (United States)

Sancho-Puchades, Manuel; Hämmerle, Christoph H F; Benic, Goran I

2015-10-01

The aim of this study was to test whether or not the intensity of artifacts around implants in cone-beam computed tomography (CBCT) differs between titanium, titanium-zirconium and zirconium dioxide implants. Twenty models of a human mandible, each containing one implant in the single-tooth gap position 45, were cast in dental stone. Five test models were produced for each of the following implant types: titanium 4.1 mm diameter (Ti4.1 ), titanium 3.3 mm diameter (Ti3.3 ), titanium-zirconium 3.3 mm diameter (TiZr3.3 ) and zirconium dioxide 3.5-4.5 mm diameter (ZrO3.5-4.5 ) implants. For control purposes, three models without implants were produced. Each model was scanned using a CBCT device. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5 mm, 1 mm and 2 mm from the implant surface (GVT est ). GV were assessed in the corresponding volumes of interest (VOI) in the control models without implants (GVC ontrol ). Differences of gray values (ΔGV) between GVT est and GVC ontrol were calculated as percentages. One-way ANOVA and post hoc tests were applied to detect differences between implant types. Mean ΔGV for ZrO3.5-4.5 presented the highest absolute values, generally followed by TiZr3.3 , Ti4.1 and Ti3.3 implants. The differences of ΔGV between ZrO3.5-4.5 and the remaining groups were statistically significant in the majority of the VOI (P ≤ 0.0167). ΔGV for TiZr3.3 , Ti4.1 and Ti3.3 implants did not differ significantly in the most VOI. For all implant types, ΔGV showed positive values buccally, mesio-buccally, lingually and disto-lingually, whereas negative values were detected mesially and distally. Zirconium dioxide implants generate significantly more artifacts as compared to titanium and titanium-zirconium implants. The intensity of artifacts around zirconium dioxide implants exhibited in average the threefold in comparison with titanium implants. © 2014 John Wiley & Sons A/S. Published by John Wiley

Fourier series and δ-subharmonic functions of finite γ-type in a half-plane

International Nuclear Information System (INIS)

Malyutin, K G

2001-01-01

Let γ(r) be a growth function and let v(z) be a proper δ-subharmonic function in the sense of Grishin in a complex half-plane, that is v=v 1 -v 2 , where v 1 and v 2 are proper subharmonic functions (limsup z→t v i (z)≤0, for each real t, i=1,2), let λ=λ + -λ - be the full measure corresponding to v and let T(r,v) be its Nevanlinna characteristic. The class Jδ(γ) of functions of finite γ-type is defined as follows: v element of Jδ(γ) if T(r,v)≤Aγ(Br)/r for some positive constants A and B. The Fourier coefficients of v are defined in the standard way. The central result of the paper is the equivalence of the following properties: (1) v element of Jδ(γ); (2) N(r)≤A 1 γ(B 1 r)/r, where N(r)=N(r,λ + ) or N(r)=N(r,λ - ), and |c k (r,v)|≤A 2 γ(B 2 r). It is proved in addition that Jδ(γ)=JS(γ)-JS(γ), where JS(γ) is the class of proper subharmonic functions of finite γ-type

Analysis of x-ray diffraction pattern and complex plane impedance plot of polypyrrole/titanium dioxide nanocomposite: A simulation study

Science.gov (United States)

Ravikiran, Y. T.; Vijaya Kumari, S. C.

2013-06-01

To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.

Near-Net Shape Fabrication Using Low-Cost Titanium Alloy Powders

Energy Technology Data Exchange (ETDEWEB)

Dr. David M. Bowden; Dr. William H. Peter

2012-03-31

The use of titanium in commercial aircraft production has risen steadily over the last half century. The aerospace industry currently accounts for 58% of the domestic titanium market. The Kroll process, which has been used for over 50 years to produce titanium metal from its mineral form, consumes large quantities of energy. And, methods used to convert the titanium sponge output of the Kroll process into useful mill products also require significant energy resources. These traditional approaches result in product forms that are very expensive, have long lead times of up to a year or more, and require costly operations to fabricate finished parts. Given the increasing role of titanium in commercial aircraft, new titanium technologies are needed to create a more sustainable manufacturing strategy that consumes less energy, requires less material, and significantly reduces material and fabrication costs. A number of emerging processes are under development which could lead to a breakthrough in extraction technology. Several of these processes produce titanium alloy powder as a product. The availability of low-cost titanium powders may in turn enable a more efficient approach to the manufacture of titanium components using powder metallurgical processing. The objective of this project was to define energy-efficient strategies for manufacturing large-scale titanium structures using these low-cost powders as the starting material. Strategies include approaches to powder consolidation to achieve fully dense mill products, and joining technologies such as friction and laser welding to combine those mill products into near net shape (NNS) preforms for machining. The near net shape approach reduces material and machining requirements providing for improved affordability of titanium structures. Energy and cost modeling was used to define those approaches that offer the largest energy savings together with the economic benefits needed to drive implementation. Technical

Cold Spraying of Armstrong Process Titanium Powder for Additive Manufacturing

Science.gov (United States)

MacDonald, D.; Fernández, R.; Delloro, F.; Jodoin, B.

2017-04-01

Titanium parts are ideally suited for aerospace applications due to their unique combination of high specific strength and excellent corrosion resistance. However, titanium as bulk material is expensive and challenging/costly to machine. Production of complex titanium parts through additive manufacturing looks promising, but there are still many barriers to overcome before reaching mainstream commercialization. The cold gas dynamic spraying process offers the potential for additive manufacturing of large titanium parts due to its reduced reactive environment, its simplicity to operate, and the high deposition rates it offers. A few challenges are to be addressed before the additive manufacturing potential of titanium by cold gas dynamic spraying can be reached. In particular, it is known that titanium is easy to deposit by cold gas dynamic spraying, but the deposits produced are usually porous when nitrogen is used as the carrier gas. In this work, a method to manufacture low-porosity titanium components at high deposition efficiencies is revealed. The components are produced by combining low-pressure cold spray using nitrogen as the carrier gas with low-cost titanium powder produced using the Armstrong process. The microstructure and mechanical properties of additive manufactured titanium components are investigated.

Characterization and Sintering of Armstrong Process Titanium Powder

Science.gov (United States)

Xu, Xiaoyan; Nash, Philip; Mangabhai, Damien

2017-04-01

Titanium and titanium alloys have a high strength to weight ratio and good corrosion resistance but also need longer time and have a higher cost on machining. Powder metallurgy offers a viable approach to produce near net-shape complex components with little or no machining. The Armstrong titanium powders are produced by direct reduction of TiCl4 vapor with liquid sodium, a process which has a relatively low cost. This paper presents a systematic research on powder characterization, mechanical properties, and sintering behavior and of Armstrong process powder metallurgy, and also discusses the sodium issue, and the advantages and disadvantages of Armstrong process powders.

Characterization of B-H agostic compounds involved in the dehydrogenation of amine-boranes by group 4 metallocenes.

Science.gov (United States)

Zhu, Jingwen; Zins, Emilie-Laure; Alikhani, Mohammad Esmaïl

2016-12-01

For over a decade, amine-borane has been considered as a potential chemical hydrogen vector in the context of a search for cleaner energy sources. When catalyzed by organometallic complexes, the reaction mechanisms currently considered involve the formation of β-BH agostic intermediates. A thorough understanding of these intermediates may constitute a crucial step toward the identification of ideal catalysts. Topological approaches such as QTAIM and ELF revealed to be particularly suitable for the description of β-agostic interactions. When studying model catalysts, accurate theoretical calculations may be carried out. However, for a comparison with experimental data, calculations should also be carried out on large organo-metallic species, often including transition metals belonging to the second or the third row. In such a case, DFT methods are particularly attractive. Unfortunately, triple-ζ all electrons basis sets are not easily available for heavy transition metal elements. Thus, a subtle balance should be reached between the affordable level of calculations and the required accuracy of the electronic description of the systems. Herein we propose the use of B3LYP functional in combination with the LanL2DZ pseudopotential for the metal atom and 6-311++G(2d,2p) basis set for the other atoms, followed by a single point using the DKH2 relativistic Hamiltonian in combination with the B3LYP/DZP-DKH level, as a "minimum level of theory" leading to a consistent topological description of the interaction within the ELF and QTAIM framework, in the context of isolated (gas-phase) group 4 metallocene catalysts.

Ultrahighly Dispersed Titanium Oxide on Silica : Effect of Precursors on the Structure and Photocatalysis

OpenAIRE

Yoshida , S.; Takenaka , S.; Tanaka , T.; Funabiki , T.

1997-01-01

The effect of precursor on the dispersion and catalytic performance of titanium oxide supported on silica has ben investigated. The catalysts were prepared by a simple impregnation method with three kinds of titanium complexes of different ligands (bis(isopropyato)-bis(pivaroylmethanato) : DPM, acetylacetonato : ACAC, tetrakis(isopropylato) : IPRO) with the aim of preparing ultrahighly dispersed titanium oxide on silica. The XAFS study revealed that titanium species in the catalyst prepared f...

1. Mono([8]annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes

International Nuclear Information System (INIS)

Boussie, T.R.

1991-10-01

A reproducible, high-yield synthesis of mono([8]annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono([8]annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported

1. Mono([8]annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes

Energy Technology Data Exchange (ETDEWEB)

Boussie, Thomas Richard [Univ. of California, Berkeley, CA (United States)

1991-10-01

A reproducible, high-yield synthesis of mono([8]annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono([8]annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.

1. Mono((8)annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes

Energy Technology Data Exchange (ETDEWEB)

Boussie, T.R.

1991-10-01

A reproducible, high-yield synthesis of mono((8)annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono((8)annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.

Evaluation of cyclic flexural fatigue of M-wire nickel-titanium rotary instruments.

Science.gov (United States)

Al-Hadlaq, Solaiman M S; Aljarbou, Fahad A; AlThumairy, Riyadh I

2010-02-01

This study was conducted to investigate cyclic flexural fatigue resistance of GT series X rotary files made from the newly developed M-wire nickel-titanium alloy compared with GT and Profile nickel-titanium files made from a conventional nickel-titanium alloy. Fifteen files, size 30/0.04, of each type were used to evaluate the cyclic flexural fatigue resistance. A simple device was specifically constructed to measure the time each file type required to fail under cyclic flexural fatigue testing. The results of this experiment indicated that the GT series X files had superior cyclic flexural fatigue resistance than the other 2 file types made from a conventional nickel-titanium alloy (P = .004). On the other hand, the difference between the Profile and the GT files was not statistically significant. The findings of this study suggest that size 30/0.04 nickel-titanium rotary files made from the newly developed M-wire alloy have better cyclic flexural fatigue resistance than files of similar design and size made from the conventional nickel-titanium alloy. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Planar half-cell shaped precursor body

DEFF Research Database (Denmark)

2015-01-01

The invention relates to a half-cell shaped precursor body of either anode type or cathode type, the half-cell shaped precursor body being prepared to be free sintered to form a sintered or pre-sintered half-cell being adapted to be stacked in a solid oxide fuel cell stack. The obtained half......-cell has an improved planar shape, which remains planar also after a sintering process and during temperature fluctuations....

The Influence of Abutment Surface Treatment and the Type of Luting Cement on Shear Bond Strength between Titanium/Cement/Zirconia

Directory of Open Access Journals (Sweden)

Beata Śmielak

2015-01-01

Full Text Available Objectives. The objectives of this study were to evaluate the shear bond strength of zirconia cylinders on a modified titanium surface using different luting cement types. Material and Methods. Eighty titanium disks were divided into two groups (n=40, which were treated with either grinding or a combination of sandblasting and grinding. Then, each group was subdivided into 4 groups (n=10 and the disks were bonded to disks of sintered zirconia using one of four cement types (permanent: composite cement; temporary: polycarboxylate cement, zinc-oxide-eugenol cement, and resin cement. Shear bond strength (SBS was measured in a universal testing machine. Fracture pattern and site characteristic were recorded. A fractographic analysis was performed with SEM. The chemical analysis of the composition of the fractures was performed using energy-dispersive X-ray spectroscopy (EDS. The results of the experiment were analyzed with two-way analysis of variance and Tukey post hoc test. Results. The highest mean values of SBS were achieved when grinding was combined with sandblasting and when composite cement was used (18.18 MPa. In the temporary cement group, the highest mean values of SBS were for polycarboxylate cement after grinding (3.57 MPa. Conclusion. The choice of cement has a crucial influence on the titanium-cement-zirconia interface quality.

Phosphine-Thiophenolate Half-Titanocene Chlorides: Synthesis, Structure, and Their Application in Ethylene (Co-Polymerization

Directory of Open Access Journals (Sweden)

Yue-Sheng Li

2013-03-01

Full Text Available A series of novel half-titanocene complexes CpTiCl2[S-2-R-6-(PPh2C6H3] (Cp = C5H5, 2a, R = H; 2b, R = Ph; 2c, R = SiMe3 have been synthesized by treating CpTiCl3 with the sodium of the ligands, 2-R-6-(PPh2C6H3SNa, which were prepared by the corresponding ligands and NaH. These complexes have been characterized by 1H, 13C and 31P NMR as well as elemental analyses. Structures for 2a–b were further confirmed by X-ray crystallography. Complexes 2a–b adopt five-coordinate, distorted square-pyramid geometry around the titanium center, in which the equatorial positions are occupied by sulfur and phosphorus atoms of the chelating phosphine-thiophenolate and two chlorine atoms, and the cyclopentadienyl ring is coordinated on the axial position. The complexes 2a–c were investigated as the catalysts for ethylene polymerization and copolymerization of ethylene with norbornene in the presence of MMAO or Ph3CB(C6F54/iBu3Al as the cocatalyst. All complexes exhibited low to moderate activities towards homopolymerization of ethylene. However, they displayed moderate to high activities towards copolymerization of ethylene with norbornene.

A more accurate half-discrete Hardy-Hilbert-type inequality with the logarithmic function.

Science.gov (United States)

Wang, Aizhen; Yang, Bicheng

2017-01-01

By means of the weight functions, the technique of real analysis and Hermite-Hadamard's inequality, a more accurate half-discrete Hardy-Hilbert-type inequality related to the kernel of logarithmic function and a best possible constant factor is given. Moreover, the equivalent forms, the operator expressions, the reverses and some particular cases are also considered.

Project Half Double

DEFF Research Database (Denmark)

Svejvig, Per; Ehlers, Michael; Adland, Karoline Thorp

activities carried out within the framework of the projects. The formal part of Project Half Double was initiated in June 2015. We started out by developing, refining and testing the Half Double methodology on seven pilot projects in the first phase of the project, which will end June 2016. The current......Project Half Double has a clear mission to succeed in finding a project methodology that can increase the success rate of our projects while increasing the speed at which we generate new ideas and develop new products and services. Chaos and complexity should be seen as a basic condition...... and as an opportunity rather than a threat and a risk. We are convinced that by doing so, we can strengthen Denmark’s competitiveness and play an important role in the battle for jobs and future welfare. The overall goal is to deliver “projects in half the time with double the impact”, where projects in half the time...

Titanium nanostructures for biomedical applications

Science.gov (United States)

Kulkarni, M.; Mazare, A.; Gongadze, E.; Perutkova, Š.; Kralj-Iglič, V.; Milošev, I.; Schmuki, P.; Iglič, A.; Mozetič, M.

2015-02-01

Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO2) nanotubes, using a simple electrochemical anodisation method of the metallic substrate and other processes such as the hydrothermal or sol-gel template. One key advantage of using TiO2 nanotubes in cell interactions is based on the fact that TiO2 nanotube morphology is correlated with cell adhesion, spreading, growth and differentiation of mesenchymal stem cells, which were shown to be maximally induced on smaller diameter nanotubes (15 nm), but hindered on larger diameter (100 nm) tubes, leading to cell death and apoptosis. Research has supported the significance of nanotopography (TiO2 nanotube diameter) in cell adhesion and cell growth, and suggests that the mechanics of focal adhesion formation are similar among different cell types. As such, the present review will focus on perhaps the most spectacular and surprising one-dimensional structures and their unique biomedical applications for increased osseointegration, protein interaction and antibacterial properties.

Titanium nanostructures for biomedical applications

International Nuclear Information System (INIS)

Kulkarni, M; Gongadze, E; Perutkova, Š; A Iglič; Mazare, A; Schmuki, P; Kralj-Iglič, V; Milošev, I; Mozetič, M

2015-01-01

Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO 2 ) nanotubes, using a simple electrochemical anodisation method of the metallic substrate and other processes such as the hydrothermal or sol-gel template. One key advantage of using TiO 2 nanotubes in cell interactions is based on the fact that TiO 2 nanotube morphology is correlated with cell adhesion, spreading, growth and differentiation of mesenchymal stem cells, which were shown to be maximally induced on smaller diameter nanotubes (15 nm), but hindered on larger diameter (100 nm) tubes, leading to cell death and apoptosis. Research has supported the significance of nanotopography (TiO 2 nanotube diameter) in cell adhesion and cell growth, and suggests that the mechanics of focal adhesion formation are similar among different cell types. As such, the present review will focus on perhaps the most spectacular and surprising one-dimensional structures and their unique biomedical applications for increased osseointegration, protein interaction and antibacterial properties. (topical review)

Microstructure, elastic deformation behavior and mechanical properties of biomedical β-type titanium alloy thin-tube used for stents.

Science.gov (United States)

Tian, Yuxing; Yu, Zhentao; Ong, Chun Yee Aaron; Kent, Damon; Wang, Gui

2015-05-01

Cold-deformability and mechanical compatibility of the biomedical β-type titanium alloy are the foremost considerations for their application in stents, because the lower ductility restricts the cold-forming of thin-tube and unsatisfactory mechanical performance causes a failed tissue repair. In this paper, β-type titanium alloy (Ti-25Nb-3Zr-3Mo-2Sn, wt%) thin-tube fabricated by routine cold rolling is reported for the first time, and its elastic behavior and mechanical properties are discussed for the various microstructures. The as cold-rolled tube exhibits nonlinear elastic behavior with large recoverable strain of 2.3%. After annealing and aging, a nonlinear elasticity, considered as the intermediate stage between "double yielding" and normal linear elasticity, is attributable to a moderate precipitation of α phase. Quantitive relationships are established between volume fraction of α phase (Vα) and elastic modulus, strength as well as maximal recoverable strain (εmax-R), where the εmax-R of above 2.0% corresponds to the Vα range of 3-10%. It is considered that the "mechanical" stabilization of the (α+β) microstructure is a possible elastic mechanism for explaining the nonlinear elastic behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of gels with basis of titanium tungstates as matrixes of radioactive generators

International Nuclear Information System (INIS)

Galico C, L.

2005-01-01

The heteropolyanions, compounds formed by the union of molybdates or tungstates polyanions with atoms of metals like zirconium, titanium, cerium, thorium, tin, etc., have been used as generator matrixes of 99m Tc or 188 Re. Particularly they have been studied and produced successfully in our laboratory, generators of 99 Mo/ 99 m Tc at basis of gels zirconium molybdates and titanium molybdates. Considering that the molybdenum and tungsten, as well as the technetium and the rhenium, its belong to the same groups of transition metals, it is feasible that gels can be synthesized at basis of titanium tungstates, continuing a methodology similar to that of the gels titanium molybdates or zirconium molybdates, to produce generators 188 W/ 188 Re. The 188 Re possess nuclear characteristics that make it attractive for therapeutic applications, since, it emits β - particles of a great energy (2.12 MeV); joined to the possibility of being able to unite to different ligands (bifunctional agents) and biomolecules (antibodies or fragments of proteins), as it makes the 99m Tc, useful in radioimmunotherapy. Commercially the 188 Re generators use a chromatographic column loaded with alumina where the 188 Re, it is adsorbed and eluted the 188 ReO 4 - by means of a saline solution The alumina adsorbs around 0.2% of the 188 Re, situation that forces to use 188 Re of a high specific activity. The use of the gels technology, allows to work with medium or low specific activities of 188 Re, opening the possibility of their production in countries whose nuclear capacity is medium or low. In particular, the synthesized gels with basis of titanium offer the possibility of being synthesized with non active material, for later on to be irradiated and directly produce the generator, since, the titanium 51 Ti, unique radioisotope produced by the titanium, has a half life of 5.79 min. This synthesis method avoids the manipulation of radioactive material during the synthesis of the gels, process

A more accurate half-discrete Hardy-Hilbert-type inequality with the logarithmic function

Directory of Open Access Journals (Sweden)

Aizhen Wang

2017-06-01

Full Text Available Abstract By means of the weight functions, the technique of real analysis and Hermite-Hadamard’s inequality, a more accurate half-discrete Hardy-Hilbert-type inequality related to the kernel of logarithmic function and a best possible constant factor is given. Moreover, the equivalent forms, the operator expressions, the reverses and some particular cases are also considered.

Immediate loading of titanium hexed screw-type implants in the edentulous patient: case report.

Science.gov (United States)

Calvo, M P; Muller, E; Garg, A K

2000-01-01

Histologic and histomorphometric studies in both animals and humans have shown that more rapid and greater bone-to-implant contact can be achieved with implants that incorporate certain surface characteristics compared with the original machined-surface implants. Such findings are significant because various implant designs may allow the fixtures to sufficiently resist functional loading sooner than originally thought. The case report presented here indicates that immediate loading of hexed titanium screw-type implants in the anterior mandible can lead to successful osseointegration and clinical outcome. The number of implants placed, their distribution, and the type of rigid connection are critical considerations for immediate loading. A bone height that can accommodate dental implants > or = 10 mm long is recommended. Biomechanically, the implants to be immediately loaded must be stable and resistant to macromovement to ensure good osseointegration.

Linear uranium complexes X2UL5 with L=cyanide, iso-cyanate: DFT evidence for similarities between uranyl (X = O) and uranocene (X = Cp) derivatives

International Nuclear Information System (INIS)

Iche-Tarrat, N.; Marsden, Colin J.; Barros, N.; Maron, L.; Barros, N.

2008-01-01

A DFT study of the isostructural compounds [UO 2 L 5 ] n- with n=3-5 and linear [Cp 2 UL 5 ] m- with m=1-3 has been carried out for two different anionic ligands. Structurally stable structures are obtained for all systems. The coordination competition between cyanide (CN - ) and isocyanide (NC - ) as well as between cyanate (OCN - ) and iso-cyanate (NCO - ) has been studied in the uranyl case. A clear preference for cyanide and iso-cyanate complexes is reported. The coordination of five ligands in the equatorial plane is rationalized by the analysis of the MO diagram of both systems. Moreover, the qualitative comparison of the two MO diagrams shows a high similarity in agreement with the isolobality concept. The existence of linear [Cp 2 UL 5 ] - organometallic U(VI) complexes is thus proposed, as well as the possibility of obtaining complexes of both types for U(VI) and U(V) with OCN - ligands. In addition, the U(IV) linear metallocene is calculated to be stable for the latter ligand. (authors)

Synthesis and spectroscopic studies of mono- and dicyclopentadienyl titanium (IV)/zirconium (IV) derivatives with S-alkyl-β-N-(acetylferrocenyl) methylene dithiocarbazates

International Nuclear Information System (INIS)

Srivastava, B.K.; Srivastava, S.K.; Pandey, O.P.; Sengupta, S.K.

1996-01-01

The reactions of dicyclopentadienyl titanium (IV)/zirconium (IV) dichloride and monocyclopentadienyl titanium (IV) trichloride with thio-Schiff bases (LH), derived by the condensation of S-methyl/ethyl/propyl dithiocarbazic acid and acetylferrocene have been carried out under inert atmosphere and anhydrous conditions in different stoichiometric ratios. Complexes of the types Cp 2 M(L)Cl, CpM(L) 2 Cl (M= Ti(IV) or Zr(IV)), CpTi(L)Cl 2 , CpTi(L) 2 Cl are synthesised and characterized by elemental analysis, electrical conductance, magnetic moment and spectral (electronic, infrared, 1 H NMR) data. (author). 12 refs., 1 tab

Label-free Fab and Fc affinity/avidity profiling of the antibody complex half-life for polyclonal and monoclonal efficacy screening.

Science.gov (United States)

Read, Thomas; Olkhov, Rouslan V; Williamson, E Diane; Shaw, Andrew M

2015-09-01

A unified approach to affinity screening for Fab and Fc interactions of an antibody for its antigen and FcγR receptor has been developed. An antigen array is used for the Fab affinity and cross-reactivity screening and protein A/G proxy is the FcγR receptor. The affinities are derived using a simple 1:1 binding model with a consistent error analysis. The association and dissociation kinetics are measured over optimised times for accurate determination. The Fab/Fc affinities are derived for ten antibodies: mAb-actin (mouse), pAb-BSA (sheep), pAb-collagen V (rabbit), pAb-CRP (goat), mAb-F1 (mouse), mAbs (mouse) 7.3, 12.3, 29.3, 36.3 and 46.3 raised against LcrV in Yersinia pestis. The rate of the dissociation of antigen-antibody complexes relates directly to their immunological function as does the Fc-FcγR complex and a new half-life plot has been defined with a Fab/Fc half-life range of 17-470 min. The upper half-life value points to surface avidity. Two antibodies that are protective as an immunotherapy define a Fab half-life >250 min and an Fc half-life >50 min as characteristics of ideal interactions which can form the basis of an antibody screen for immunotherapy.

An evaluation of two types of nickel-titanium wires in terms of micromorphology and nickel ions' release following oral environment exposure.

Science.gov (United States)

Ghazal, Abdul Razzak A; Hajeer, Mohammad Y; Al-Sabbagh, Rabab; Alghoraibi, Ibrahim; Aldiry, Ahmad

2015-01-01

This study aimed to compare superelastic and heat-activated nickel-titanium orthodontic wires' surface morphology and potential release of nickel ions following exposure to oral environment conditions. Twenty-four 20-mm-length distal cuts of superelastic (NiTi Force I®) and 24 20-mm-length distal cuts of heat-activated (Therma-Ti Lite®) nickel-titanium wires (American Orthodontics, Sheboygan, WI, USA) were divided into two equal groups: 12 wire segments left unused and 12 segments passively exposed to oral environment for 1 month. Scanning electron microscopy and atomic force microscopy were used to analyze surface morphology of the wires which were then immersed in artificial saliva for 1 month to determine potential nickel ions' release by means of atomic absorption spectrophotometer. Heat-activated nickel-titanium (NiTi) wires were rougher than superelastic wires, and both types of wires released almost the same amount of Ni ions. After clinical exposure, more surface roughness was recorded for superelastic NiTi wires and heat-activated NiTi wires. However, retrieved superelastic NiTi wires released less Ni ions in artificial saliva after clinical exposure, and the same result was recorded regarding heat-activated wires. Both types of NiTi wires were obviously affected by oral environment conditions; their surface roughness significantly increased while the amount of the released Ni ions significantly declined.

Sealing glasses for titanium and titanium alloys

Science.gov (United States)

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Synthesis of p-type nickel oxide nanosheets on n-type titanium dioxide nanorod arrays for p-n heterojunction-based UV photosensor

Science.gov (United States)

Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Abdullah, M. A. R.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a novel and facile immersion method in a glass container. The synthesis and deposition of p-type nickel oxide (NiO) nanosheets (NS) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated TNAs/NiO NS based UV photosensor exhibited a highly increased photocurrent of 4.3 µA under UV radiation (365 nm, 750 µW/cm2) at 1.0 V reverse bias. In this study, the fabricated TNAs/NiO NS p-n heterojunction based photodiode showed potential applications for UV photosensor based on the stable photo-generated current attained under UV radiation.

New insights into the complex photoluminescence behaviour of titanium white pigments

NARCIS (Netherlands)

van Driel, B.A.; Artesani, A.; van den Berg, Klaas Jan; Dik, J.; Mosca, S.; Rossenaar, B.; Hoekstra, J.; Davies, A.; Nevin, A.; Valentini, G.; Comelli, D.

2018-01-01

This work reports the analysis of the time-resolved photoluminescence behaviour on the nanosecond and microsecond time scale of fourteen historical and contemporary titanium white pigments. The pigments were produced with different production methods and post-production treatments, giving rise to

NMR studies in the half-Heusler type compound YbPtSb

Energy Technology Data Exchange (ETDEWEB)

Koyama, T; Abe, M; Mito, T; Ueda, K; Kohara, T [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan); Suzuki, H S, E-mail: t-koyama@sci.u-hyogo.ac.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan)

2011-01-01

{sup 121}Sb and {sup 19B}Pt nuclear magnetic resonance (NMR) has been studied in the half-Heusler type compound YbPtSb to obtain information on local magnetic behavior. The characteristics of the localized 4f spins are observed in the Cuire-Weiss type behavior of the Knight shifts K for both {sup 121}Sb and {sup 19B}Pt. From the slope of K-{sub {chi}} plots we estimated hyperfine coupling constants of -3.8 and -4.6 kOe/{mu}{sub B} at Sb and Pt sites, respectively. It was found that the spin-echo decay rate 1/T{sub 2} of {sup 121}Sb shows a clear peaks at 10 K. Similar tendency was also observed in case of {sup 19B}Pt. However, static properties do not show any anomalies near 10 K.

Multicycle mechanical performance of titanium and stainless steel transpedicular spine implants.

Science.gov (United States)

Pienkowski, D; Stephens, G C; Doers, T M; Hamilton, D M

1998-04-01

This was a prospective in vitro study comparing titanium alloy and stainless steel alloy in transpedicular spine implants from two different manufactures. To compare the multicycle mechanical performance of these two alloys, used in each of two different implant designs. Transpedicular spine implants primarily have been manufactured from stainless steel, but titanium alloy offers imaging advantages. However, the notch sensitivity of titanium alloy has caused concern regarding how implants made from this material will compare in stiffness and fatigue life with implants made from stainless steel. Twenty-four implants (two alloys, two designs, six implants per group) were mounted in machined polyethylene wafers and repetitively loaded (up to 1 million cycles) from 80 N to 800 N using a 5-Hertz sinusoidal waveform. Load and displacement data were automatically and periodically sampled throughout the entire test. Implant stiffness increased with cycle load number, reached a steady state, then declined just before fatigue failure. Stiffness varied less in titanium transpedicular spine implants than in their stainless counterparts. All stainless steel implant types were stiffer (steady-state value, P titanium alloy counterparts. One titanium implant design failed with fewer (P stainless steel counterpart, whereas a stainless steel implant of another design failed with fewer (P titanium counterpart. Overall, fatigue life, i.e., the total number of load cycles until failure, was related to implant type (P implant material. A transpedicular spine implant's fatigue lifetime depends on both the design and the material and cannot be judged on material alone. Stainless steel implants are stiffer than titanium alloy implants of equal design and size; however, for those designs in which the fatigue life of the titanium alloy version is superior, enlargement of the implant's components can compensate for titanium's lower modulus of elasticity and result in an implant equally stiff

Polarographic determination of the titanium and niobium content of zirconium alloys

International Nuclear Information System (INIS)

Levin, R; Gabra, J.

1978-03-01

A method is described for the polarographic determination of titanium and niobium in zirconium alloys in the concentration range of 0.1% to 4% of each of the determined metals. To assure the complete dissolution of the sample a mixture of nitric acid and hydrofluoric acid is used. After evaporating these acids in the presence of sulphuric acid, the contents are determined polarographically with a supporting electrolyte solution of 0.1M EDTA, 0.33M potassium sulfate and 0.4M sodium acetate, buffered to pH 4 with acetic acid. The half-wave potential (Esub(1/2)) of titanium is -0.35V and that of niobium is -0.67 V. (author)

Research on development and application of titanium and zirconium alloys

International Nuclear Information System (INIS)

Suzuki, Toshiyuki; Sasano, Hisaoki; Uehara, Shigeaki; Nakano, Osamu; Shibata, Michio

1983-01-01

It can be said that titanium and zirconium are new metals from the viewpoint of the history of metals, but both have grown to the materials supporting modern industries, titanium alloys in aerospace and ocean development, and zirconium alloys in nuclear power application. However, the properties of both alloys have not yet been clarified. In this study, the synthesis of TiNi and its properties, precipitation hardening type titanium alloys, and the effect of oxygen on the mechanical properties of both alloys were examined. TiNi is the typical intermetallic compound which shows the peculiar properties. The method of its synthesis by diffusion was examined, and it was clarified that it is useful as a structural material and also as a functional material. Precipitation hardening type alloys have not been developed in titanium alloys, but in this study, the feasibility of several alloy systems was found. Both titanium and zirconium have large affinity to oxygen, and the oxygen absorbed in the manufacturing process cannot be reduced. The tensile property of both alloys was examined in wide temperature range, and the effect of oxygen was clarified. (Kako, I.)

Surface modification of titanium and titanium alloys by ion implantation.

Science.gov (United States)

Rautray, Tapash R; Narayanan, R; Kwon, Tae-Yub; Kim, Kyo-Han

2010-05-01

Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, to improve the biological, chemical, and mechanical properties, surface modification is often performed. In view of this, the current review casts new light on surface modification of titanium and titanium alloys by ion beam implantation. (c) 2010 Wiley Periodicals, Inc.

Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

Science.gov (United States)

Nemati, Sima Hashemi; Hadjizadeh, Afra

2017-08-01

Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO 2 ) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO 2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO 2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO 2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO 2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

Comparison of stainless steel and titanium alloy orthodontic miniscrew implants: a mechanical and histologic analysis.

Science.gov (United States)

Brown, Ryan N; Sexton, Brent E; Gabriel Chu, Tien-Min; Katona, Thomas R; Stewart, Kelton T; Kyung, Hee-Moon; Liu, Sean Shih-Yao

2014-04-01

The detailed mechanical and histologic properties of stainless steel miniscrew implants used for temporary orthodontic anchorage have not been assessed. Thus, the purpose of this study was to compare them with identically sized titanium alloy miniscrew implants. Forty-eight stainless steel and 48 titanium alloy miniscrew implants were inserted into the tibias of 12 rabbits. Insertion torque and primary stability were recorded. One hundred grams of tensile force was applied between half of the implants in each group, resulting in 4 subgroups of 24 specimens each. Fluorochrome labeling was administered at weeks 4 and 5. When the rabbits were euthanized at 6 weeks, stability and removal torque were measured in half (ie, 12 specimens) of each of the 4 subgroups. Microdamage burden and bone-to-implant contact ratio were quantified in the other 12 specimens in each subgroup. Mixed model analysis of variance was used for statistical analysis. All implants were stable at insertion and after 6 weeks. The only significant difference was the higher (9%) insertion torque for stainless steel. No significant differences were found between stainless steel and titanium alloy miniscrew implants in microdamage burden and bone-to-implant contact regardless of loading status. Stainless steel and titanium alloy miniscrew implants provide the same mechanical stability and similar histologic responses, suggesting that both are suitable for immediate orthodontic clinical loads. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Half-Sandwich Ru(II and Os(II Bathophenanthroline Complexes Containing a Releasable Dichloroacetato Ligand

Directory of Open Access Journals (Sweden)

Pavel Štarha

2018-02-01

Full Text Available We report on the preparation and thorough characterization of cytotoxic half-sandwich complexes [Ru(η6-pcym(bphen(dca]PF6 (Ru-dca and [Os(η6-pcym(bphen(dca]PF6 (Os-dca containing dichloroacetate(1– (dca as the releasable O-donor ligand bearing its own cytotoxicity; pcym = 1-methyl-4-(propan-2-ylbenzene (p-cymene, bphen = 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline. Complexes Ru-dca and Os-dca hydrolyzed in the water-containing media, which led to the dca ligand release (supported by 1H NMR and electrospray ionization mass spectra. Mass spectrometry studies revealed that complexes Ru-dca and Os-dca do not interact covalently with the model proteins cytochrome c and lysozyme. Both complexes exhibited slightly higher in vitro cytotoxicity (IC50 = 3.5 μM for Ru-dca, and 2.6 μM for Os-dca against the A2780 human ovarian carcinoma cells than cisplatin (IC50 = 5.9 μM, while their toxicity on the healthy human hepatocytes was found to be IC50 = 19.1 μM for Ru-dca and IC50 = 19.7 μM for Os-dca. Despite comparable cytotoxicity of complexes Ru-dca and Os-dca, both the complexes modified the cell cycle, mitochondrial membrane potential, and mitochondrial cytochrome c release by a different way, as revealed by flow cytometry experiments. The obtained results point out the different mechanisms of action between the complexes.

Standard digital reference images for titanium castings

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 The digital reference images provided in the adjunct to this standard illustrate various types and degrees of discontinuities occurring in titanium castings. Use of this standard for the specification or grading of castings requires procurement of the adjunct digital reference images, which illustrate the discontinuity types and severity levels. They are intended to provide the following: 1.1.1 A guide enabling recognition of titanium casting discontinuities and their differentiation both as to type and degree through digital radiographic examination. 1.1.2 Example digital radiographic illustrations of discontinuities and a nomenclature for reference in acceptance standards, specifications and drawings. 1.2 The digital reference images consist of seventeen digital files each illustrating eight grades of increasing severity. The files illustrate seven common discontinuity types representing casting sections up to 1-in. (25.4-mm). 1.3 The reference radiographs were developed for casting sections up to 1...

Electrodeposition of amine-terminatedpoly(ethylene glycol) to titanium surface

International Nuclear Information System (INIS)

Tanaka, Yuta; Doi, Hisashi; Iwasaki, Yasuhiko; Hiromoto, Sachiko; Yoneyama, Takayuki; Asami, Katsuhiko; Imai, Hachiro; Hanawa, Takao

2007-01-01

The immobilization of poly(ethylene glycol), PEG, to a solid surface is useful to functionalize the surface, e.g., to prevent the adsorption of proteins. No successful one-stage technique for the immobilization of PEG to base metals has ever been developed. In this study, PEG in which both terminals or one terminal had been modified with amine bases was immobilized onto a titanium surface using electrodeposition. PEG was dissolved in a NaCl solution, and electrodeposition was carried out at 310 K with - 5 V for 300 min. The thickness of the deposited PEG layer was evaluated using ellipsometry, and the bonding manner of PEG to the titanium surface was characterized using X-ray photoelectron spectroscopy after electrodeposition. The results indicated that a certain amount of PEG was adsorbed on titanium through both electrodeposition and immersion when PEG was terminated by amine. However, terminated amines existed at the surface of titanium and were combined with titanium oxide as N-HO by electrodeposition, while amines randomly existed in the molecule and showed an ionic bond with titanium oxide by immersion. The electrodeposition of PEG was effective for the inhibition of albumin adsorption. This process is useful for materials that have electroconductivity and a complex morphology

Calcium phosphate-based coatings on titanium and its alloys.

Science.gov (United States)

Narayanan, R; Seshadri, S K; Kwon, T Y; Kim, K H

2008-04-01

Use of titanium as biomaterial is possible because of its very favorable biocompatibility with living tissue. Titanium implants having calcium phosphate coatings on their surface show good fixation to the bone. This review covers briefly the requirements of typical biomaterials and narrowly focuses on the works on titanium. Calcium phosphate ceramics for use in implants are introduced and various methods of producing calcium phosphate coating on titanium substrates are elaborated. Advantages and disadvantages of each type of coating from the view point of process simplicity, cost-effectiveness, stability of the coatings, coating integration with the bone, cell behavior, and so forth are highlighted. Taking into account all these factors, the efficient method(s) of producing these coatings are indicated finally.

Yttrocene Chloride and Methyl Complexes with Variously\

Czech Academy of Sciences Publication Activity Database

Fridrichová, A.; Varga, Vojtěch; Pinkas, Jiří; Lamač, Martin; Růžička, A.; Horáček, Michal

2016-01-01

Roč. 2016, č. 23 (2016), s. 3713-3721 ISSN 1434-1948 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : Alkylation * Cyclopentadienyl ligands * Metallocenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.444, year: 2016

Haloacyl complexes of boron, [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I).

Science.gov (United States)

Finze, Maik; Bernhardt, Eduard; Willner, Helge; Lehmann, Christian W

2005-11-04

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].

Strain localization during tensile Hopkinson bar testing of commercially pure titanium and Ti6Al4V titanium alloy

Directory of Open Access Journals (Sweden)

Moćko Wojciech

2015-01-01

Full Text Available The goal of the analysis was to determine the strain localization for various specimen shapes (type A and type B according to PN-EN ISO 26203-1 standard and different loading conditions, i.e. quasi- static and dynamic. Commercially pure titanium (Grade 2 and titanium alloy Ti6Al4V (Grade 5 were selected for the tests. Tensile loadings were applied out using servo-hydraulic testing machine and tensile Hopkinson bar with pre-tension. The results were recorded using ARAMIS system cameras and fast camera Phantom V1210, respectively at quasi-static and dynamic loading conditions. Further, specimens outline was determined on the basis of video data using TEMA MOTION software. The strain distribution on the specimen surface was estimated using digital image correlation method. The larger radius present in the specimen of type B in comparison to specimen of type A, results in slight increase of the elongation for commercially pure titanium at both quasi-static and dynamic loading conditions. However this effect disappears for Ti6Al4V alloy. The increase of the elongation corresponds to the stronger necking effect. Material softening due to increase of temperature induced by plastic work was observed at dynamic loading conditions. Moreover lower elongation at fracture point was found at high strain rates for both materials.

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15

NARCIS (Netherlands)

Santen, van R.A.; Zhang, Lei; Abbenhuis, H.C.L.; Gerritsen, G.; Ní Bhriain, N.M.; Magusin, P.C.M.M.; Mezari, B.; Han, W.; Yang, Q.; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active

Effect of titanium on microstructural changes in SUS 316 stainless steels

International Nuclear Information System (INIS)

Kawanishi, H.; Yamada, M.; Fukuya, K.; Ishino, S.

1982-01-01

The microstructural changes have been examined in order to study the effect of titanium addition to type 316 stainless steels on void swelling. Titanium ions of 400 keV from an accelerator have been implanted at room temperature to solution treated SUS 316 stainless steels which have the original titanium content of 0.02 wt.% to the concentration increase of titanium by 0.01, 0.02 and 0.1 wt.%. Following the preinjection of 20 at.ppm helium at ambient temperature, 400 keV-aluminium ions have been irradiated to the specimen to 40 dpa at 550, 625 and 675 0 C. The TEM observations have revealed that the void number density is drastically increased in the specimen with the content of implanted titanium of more than 0.01 wt.%, whereas the void diameter is remarkably decreased with the titanium content. (orig.)

Classification of titanium dioxide; Clasificacion del dioxido de titanio

Energy Technology Data Exchange (ETDEWEB)

Macias B, L.R. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Garcia C, R.M.; Maya M, M.E. [Secretaria de Hacienda y Credito Publico de Mexico, Mexico (Mexico); Ita T, A. De [Universidad Autonoma Metropolitana Azcapotzalco, Mexico (Mexico); Palacios G, J. [Instituto Politecnico Nacional (Mexico)

2002-07-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO{sub 2}. The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

Factors influencing catalytic behavior of titanium complexes bearing bisphenolate ligands toward ring-opening polymerization of L-lactide and ε-caprolactone

Directory of Open Access Journals (Sweden)

M-T. Jiang

2018-02-01

Full Text Available A series of titanium complexes bearing substituted diphenolate ligands (RCH(phenolate2, where R = H, CH3, o-OTs-phenyl, o-F-phenyl, o-OMe-phenyl, 2,4-OMe-phenyl was synthesized and studied as catalysts for the ring opening polymerization of L-lactide and ε-caprolactone. Ligands were designed to probe the role of chelate effect and steric effect in the catalytic performance. From the structure of triphenolate (with one extra coordination site than diphenolate ligand Ti complex, TriOTiOiPr2, we found no additional chelation to influence the catalytic activity of Ti complexes. It was found that bulky aryl groups in the diphenolate ligands decreased the rate of polymerization most. We conclude that steric effect is the most controlling factor in these polymerization reactions by using Ti complexes bearing diphenolate ligands as catalysts since it is responsible for the exclusion of needed space for incoming monomer by the bulky substituents on the catalyst.

COMPARISON OF STATISTICALLY CONTROLLED MACHINING SOLUTIONS OF TITANIUM ALLOYS USING USM

Directory of Open Access Journals (Sweden)

R. Singh

2010-06-01

Full Text Available The purpose of the present investigation is to compare the statistically controlled machining solution of titanium alloys using ultrasonic machining (USM. In this study, the previously developed Taguchi model for USM of titanium and its alloys has been investigated and compared. Relationships between the material removal rate, tool wear rate, surface roughness and other controllable machining parameters (power rating, tool type, slurry concentration, slurry type, slurry temperature and slurry size have been deduced. The results of this study suggest that at the best settings of controllable machining parameters for titanium alloys (based upon the Taguchi design, the machining solution with USM is statistically controlled, which is not observed for other settings of input parameters on USM.

Hydrogen embrittlement of titanium tested with fracture mechanics specimens

International Nuclear Information System (INIS)

Aho-Mantila, I.; Rahko, P.

1990-11-01

Titanium is one of the possible canister materials for spent nuclear fuel. The aim of this study is to determine whether the hydrogen embrittlement of titanium could be a possible deterioration mechanism of titanium canisters. This experimental study was preceded by a literature review and an experimental study on crack nucleation. Tests in this study were carried out with hydrogen charged fracture mechanics specimens. The studied hydrogen contents were as received, 100 ppm, 200 ppm, 500 ppm and 700 ppm and the types of the studied titanium were ASTM Grades 2 and 12. Test methods were slow tensile test (0.027 mm/h) and fatigue test (stress ratio 0.7 or 0.8 and frequency 5 Hz). According to the literature titanium may be embrittled by hydrogen at slow strain rates and cracking may occur under sustained load. In this study no evidence of hydrogen embrittlement was noticed in slow strain rate tension with bulk hydrogen contents up to 700 ppm. The fatigue tests of titanium Grades 2 and 12 containing 700 ppm hydrogen showed even slower crack growth compared to the as received condition. Very high hydrogen contents well in eccess of 700 ppm on the surface of titanium can, however, facilitate surface crack nucleation and crack growth, as shown in the previous study

Modification of Clays by Sol-Gel Reaction and Their Use in the Ethylene In Situ Polymerization for Obtaining Nanocomposites

Directory of Open Access Journals (Sweden)

E. Moncada

2012-01-01

Full Text Available The nanocomposites formation by in situ polymerization used a metallocene catalyst (butyl-2-cyclopentadienyl zirconium 2-chlorines and a hectorite synthetic clay type which is discussed. This research was carried out in two phases. The first phase consisted of mixing the components of the metallocenic polymerization reaction (metallocene-methylaluminoxane-ethylene with clay in a reactor. In the second phase, the metallocenic catalytic system was supported by clay particles and then a polymerization reaction was made. In this second phase, the clay particles were modified using a sol-gel reaction with different pH values: pH = 3, pH = 8, and pH = 12. The results were compared in terms of the catalytic activity in the different systems (phase 1 and phase 2 and the nanoparticle morphology of nanocomposites generated in this study.

Low-temperature atmospheric oxidation of mixtures of titanium and carbon black or brown

International Nuclear Information System (INIS)

Elizarova, V.A.; Babaitsev, I.V.; Barzykin, V.V.; Gerusova, V.P.; Rozenband, V.I.

1984-01-01

This article reports on the thermogravimetric investigation of mixtures of titanium no. 2 and carbon black with various mass carbon contents. Adding carbon black (as opposed to boron) to titanium leads to an increase in the rate of heat release of the oxidation reaction. An attempt is made to clarify the low-temperature oxidation mechanism of titanium mixtures in air. An x-ray phase and chemical (for bound carbon) analysis of specimens of a stoichiometric Ti + C mixture after heating in air to a temperature of 650 0 C at the rate of 10 0 /min was conducted. The results indicate that the oxidation of the titanium-carbon mixture probably proceeds according to a more complex mechanism associated with the transport of the gaseous carbon oxidation products and their participation in the titanium oxidation

Vacancy induced half-metallicity in half-Heusler semiconductors

KAUST Repository

Zhu, Zhiyong

2011-09-28

First-principles calculations are performed to investigate the effect of vacancies on the electronic structure and magnetic properties of the two prototypical half-Heusler semiconductors NiTiSn and CoTiSb. The spin degeneracy of the host materials is broken for all types of isolated vacancies under consideration, except for Ni-deficient NiTiSn. A half-metallic character is identified in Sn-deficient NiTiSn and Co/Ti/Sb-deficient CoTiSb. We can explain our findings by introducing an extending Slater-Pauling rule for systems with defects. A ferromagnetic ordering of the local moments due to double exchange appears to be likely.

Titanium metal: extraction to application

Energy Technology Data Exchange (ETDEWEB)

Gambogi, Joseph (USGS, Reston, VA); Gerdemann, Stephen J.

2002-09-01

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Microstructural control of thin-film diffusion-brazed titanium

International Nuclear Information System (INIS)

Wells, R.R.

1976-01-01

This study was designed to determine what parameters should be controlled to achieve quality joints of good toughness and high strength in titanium alloys. Emphasis was placed upon studying those parameters which provided tough joints compatible with the titanium base metal being joined. This paper is concerned with thin-film diffusion brazing based upon the eutectic system formed between copper and titanium. In order to control the joint microstructure, the copper diffusion rates and the beta-phase decomposition kinetics were studied. This information was used to produce various types of microstructures in test specimens. These were then evaluated to select the best microstructures for toughness and strength which were compatible with the titanium alloys. Results show that it is possible to accurately control properties of joints produced by thin-film diffusion brazing. This is done by controlling the initial copper content and the time-temperature parameters used in processing. Alloys studied were Ti--8Al--1Mo--1V and Ti--6Al--4V

Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

Science.gov (United States)

Li, Kuo-Tseng; Wu, Ling-Huey

2017-05-05

Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

Titanium disilicide formation by sputtering of titanium on heated silicon substrate

Science.gov (United States)

Tanielian, M.; Blackstone, S.

1984-09-01

We have sputter deposited titanium on bare silicon substrates at elevated temperatures. We find that at a substrate temperature of about 515 °C titanium silicide is formed due to the reaction of the titanium with the Si. The resistivity of the silicide is about 15 μΩ cm and it is not etchable in a selective titanium etch. This process can have applications in low-temperature, metal-oxide-semiconductor self-aligned silicide formation for very large scale integrated

The microstructure of type 304 stainless steel implanted with titanium and carbon and its relation to friction and wear tests

International Nuclear Information System (INIS)

Follstaedt, D.M.; Pope, L.E.; Knapp, J.A.; Picraux, S.T.; Yost, F.G.

1983-01-01

The authors have used transmission electron microscopy to examine the microstructure of type 304 stainless steel which was ion implanted with high doses (2 X 10 17 atoms cm -2 ) of titanium and carbon. It is found that the resulting surface alloy is an amorphous phase similar to that observed when pure iron is identically implanted. This result is important for identifying the mechanisms by which the coefficient of friction and the wear depth are reduced in unlubricated pin-on-disc tests of type 304 stainless steel implanted with titanium and carbon. The effect of temperature on the amorphous alloy during annealing in the microscope has also been examined. It is found that devitrification begins after 15 min at 500 0 C and that the alloy fully crystallizes into f.c.c., b.c.c. and TiC phases after 15 min at 650 0 C. A comparison of mechanical test results from devitrified specimens with results from amorphous specimens demonstrates that the reduction in the coefficient of friction correlates with the presence of the amorphous layer, whereas the reduction in the wear depth is obtained for both amorphous and crystalline alloys. (Auth.)

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond.

Science.gov (United States)

Leal, Mônica Barbosa; Pagnano, Valéria Oliveira; Bezzon, Osvaldo Luiz

2013-01-01

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (pcasting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (pcasting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

All welded titanium condenser adopted in atomic power plants

International Nuclear Information System (INIS)

Iwai, Nagao; Itabashi, Yukihiko

1980-01-01

Condensers in power plants are shell-and-tube type heat exchangers. Most condensers use seawater as a coolant. Their tube and tube Sheets have usually been made of brass, which resists corrosion but cannot completely prevent it; as a result, tubes sometimes corrode or erode, allowing seawater to leak into the turbine cycle. As is well known, titanium has almost complete corrosion resistance against seawater; for this reason titanium tubes have replaced brass ones in some condensers operating in Europe and the USA. Even in such condensers, though, the tube plates have still been made of brass, tightly fitted to the titanium tubes, and it has proved impossible to eliminate seawater leakage at the junctions between tubes and tube Sheets. In order to eliminate such leakage completely, the tube Sheets must be made of titanium too, and the tubes and plates must be welded together. However, the welding of titanium requires an extremely celan atmosphere, a condition very difficult to fulfill at power plant construction sites, and the use of whole welded titanium tube condensers has long been considered a practical impossibility. Such all-titanium welded condensers have now been successfully constructed and installed in two 600 MW fossil power plants and one 1100 MW nuclear power plant. This paper describes the techniques used, add in addition reviews the various materials that have been used in condenser tubes. (author)

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.

Surface characterization of nickel titanium orthodontic arch wires

Science.gov (United States)

Krishnan, Manu; Seema, Saraswathy; Tiwari, Brijesh; Sharma, Himanshu S.; Londhe, Sanjay; Arora, Vimal

2015-01-01

Background Surface roughness of nickel titanium orthodontic arch wires poses several clinical challenges. Surface modification with aesthetic/metallic/non metallic materials is therefore a recent innovation, with clinical efficacy yet to be comprehensively evaluated. Methods One conventional and five types of surface modified nickel titanium arch wires were surface characterized with scanning electron microscopy, energy dispersive analysis, Raman spectroscopy, Atomic force microscopy and 3D profilometry. Root mean square roughness values were analyzed by one way analysis of variance and post hoc Duncan's multiple range tests. Results Study groups demonstrated considerable reduction in roughness values from conventional in a material specific pattern: Group I; conventional (578.56 nm) > Group V; Teflon (365.33 nm) > Group III; nitride (301.51 nm) > Group VI (i); rhodium (290.64 nm) > Group VI (ii); silver (252.22 nm) > Group IV; titanium (229.51 nm) > Group II; resin (158.60 nm). It also showed the defects with aesthetic (resin/Teflon) and nitride surfaces and smooth topography achieved with metals; titanium/silver/rhodium. Conclusions Resin, Teflon, titanium, silver, rhodium and nitrides were effective in decreasing surface roughness of nickel titanium arch wires albeit; certain flaws. Findings have clinical implications, considering their potential in lessening biofilm adhesion, reducing friction, improving corrosion resistance and preventing nickel leach and allergic reactions. PMID:26843749

Investment casting of beta titanium alloys for aerospace applications

International Nuclear Information System (INIS)

Wheeler, D.A.; Cianci, M.S.; Vogt, R.G.

1993-01-01

The process of investment casting offers the ability to produce complex titanium components with minimal finish machining, thereby reducing their overall manufacturing cost. While aerospace applications for cast titanium have focused primarily on alpha+beta alloys, recent interest in higher strength beta alloys has prompted an examination of their suitability for investment casting. In this paper, the processing characteristics and mechanical proper-ties of Ti-1 5V-3Cr-3Al-3Sn, Ti-3Al-8V-6Cr-4Mo-4Zr, and Ti-15Mo-3Nb-3Al-0.2Si (wt.%) will be discussed. It will be shown that all three alloy compositions are readily processed using only slight modifications from current Ti-6Al-4V (wt.%) production operations. In addition, the mechanical properties of the cast product form can be manipulated through heat treatment and compare quite favorably with typical properties obtained in wrought beta titanium products. Finally, several demonstration castings are reviewed which illustrate the shape-making capabilities of the investment casting approach for beta titanium alloys

STUDY OF THERMAL BEHAVIOUR ON TITANIUM ALLOYS (TI-6AL-4V

Directory of Open Access Journals (Sweden)

VASUDEVAN D

2017-08-01

Full Text Available Titanium is recognized for its strategic importance as a unique lightweight, high strength alloyed structurally efficient metal for critical, high-performance aircraft, such as jet engine and airframe components. Titanium is called as the "space age metal" and is recognized for its high strength-to-weight ratio. Today, titanium alloys are common, readily available engineered metals that compete directly with stainless steel and Specialty steels, copper alloys, nickel based alloys and composites. Titanium alloys are needed to be heat treated in order to reduce residual stress developed during fabrication and to increase the strength. Titanium (Ti-6Al-4V alloy is an alpha, beta alloy which is solution treated at a temperature of 950 ºC to attain beta phase. This beta phase is maintained by quenching and subsequent aging to increase strength. Thermal cycling process was carried out for Ti-6Al-4V specimens using forced air cooling. Heat treated titanium alloy specimen was used to carry out various tests before and after thermal cycling, The test, like tensile properties, co-efficient of thermal expansion, Microstructure, Compression test, Vickers Hardness was examined by the following test. Coefficient of Thermal expansion was measured using Dilatometer. Tensile test was carried out at room temperature using an Instron type machine. Vickers's hardness measurement was done on the same specimen as used for the microstructural observation from near the surface to the inside specimen. Compression test was carried out at room temperature using an Instron type machine. Ti‐6Al‐4V alloy is a workhorse of titanium industry; it accounts for about 60 percent of the total titanium alloy production. The high cost of titanium makes net shape manufacturing routes very attractive. Casting is a near net shape manufacturing route that offers significant cost advantages over forgings or complicated machined parts.

Leaching of Titanium and Silicon from Low-Grade Titanium Slag Using Hydrochloric Acid Leaching

Science.gov (United States)

Zhao, Longsheng; Wang, Lina; Qi, Tao; Chen, Desheng; Zhao, Hongxin; Liu, Yahui; Wang, Weijing

2018-05-01

Acid-leaching behaviors of the titanium slag obtained by selective reduction of vanadium-bearing titanomagnetite concentrates were investigated. It was found that the optimal leaching of titanium and silicon were 0.7% and 1.5%, respectively. The titanium and silicon in the titanium slag were firstly dissolved in the acidic solution to form TiO2+ and silica sol, and then rapidly reprecipitated, forming hydrochloric acid (HCl) leach residue. Most of the silicon presented in the HCl leach residue as floccules-like silica gel, while most of the titanium was distributed in the nano-sized rod-like clusters with crystallite refinement and intracrystalline defects, and, as such, 94.3% of the silicon was leached from the HCl leach residue by alkaline desilication, and 96.5% of the titanium in the titanium-rich material with some rutile structure was then digested by the concentrated sulfuric acid. This provides an alternative route for the comprehensive utilization of titanium and silicon in titanium slag.

Spectroscopic studies on Titanium ion binding to the apo lactoferrin

International Nuclear Information System (INIS)

Moshtaghie, A.A.; Ani, M.; Arabi, M.H.

2006-01-01

Titanium is a relatively abundant element that has found growing applications in medical science and recently some of Titanium compounds are introduced as anticancer drugs. In spite of very limited data which exist on the Titanium metabolism, some proteins might be involved in the mechanism of action of Titanium up to our knowledge, there is not any report in the literature concerning binding of Titanium to apo lactoferrin. Binding of apo lactoferrin with Ti(IV)-citrate was studied by spectroflourimeterey and spectrophotometery techniques under physiological conditions. The spectroflourimeteric studies revealed a significant fluorescence quenching, that indicated binding of apo lactoferrin with Ti(IV). The same reaction was monitored through spectrophotometry technique; this represents a characteristic UV difference band at 267 nm, which is different from lac-Fe (III). Titration studies how that lactoferrin specifically binds two moles Ti(IV) as complex with citrate per mol protein. Spectroflourimeterey and spectrophotometery techniques indicated that Ti(IV) ions cause a reduction (13%-14%) in binding of Fe(III) to lactoferrin. In overall, we may come to this conclusion that this element might be involved in the iron metabolism

Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts; Alargamento da distribuicao de massa molar de polimeros sintetizados com catalisadores metalocenicos dual-site

Energy Technology Data Exchange (ETDEWEB)

Santos, Joao H.Z. dos [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica]. E-mail: jhzds@iq.ufrgs.br; Fisch, Adriano G.; Cardozo, Nilo S.M.; Secchi, Argimiro R. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Engenharia Quimica

2008-07-01

The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest. (author)

In Vivo Evaluation of Immediately Loaded Stainless Steel and Titanium Orthodontic Screws in a Growing Bone

OpenAIRE

Gritsch, Kerstin; Laroche, Norbert; Bonnet, Jeanne-Marie; Exbrayat, Patrick; Morgon, Laurent; Rabilloud, Muriel; Grosgogeat, Brigitte

2013-01-01

The present work intends to evaluate the use of immediate loaded orthodontic screws in a growing model, and to study the specific bone response. Thirty-two screws (half of stainless steel and half of titanium) were inserted in the alveolar bone of 8 growing pigs. The devices were immediately loaded with a 100 g orthodontic force. Two loading periods were assessed: 4 and 12 weeks. Both systems of screws were clinically assessed. Histological observations and histomorphometric analysis evaluate...

Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

International Nuclear Information System (INIS)

Kado, T.; Hidaka, T.; Aita, H.; Endo, K.; Furuichi, Y.

2012-01-01

Highlights: ► Cell-adhesive molecules were covalently immobilized on a Ti surface. ► Immobilized cell-adhesive molecules maintained native function on the Ti surface. ► Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully immobilized on the titanium surface and improved the compatibility of the surface

Inhibitors for the corrosion of reactive metals: titanium and zirconium and their alloys in acid media

International Nuclear Information System (INIS)

Petit, J.A.; Chatainier, G.; Dabosi, F.

1981-01-01

The search for effective corrosion inhibitors for titanium and zirconium in acid media is growing because of the considerable increase in the use of these materials in chemical process equipment. It still remains limited, as appears from this review, because of the exceptionally high corrosion resistance of the metals. Titanium has received the greater attention. Its corrosion rate can be lowered by introduction in the medium of multivalent ions, inorganic and organic oxidants. Care should be taken to hold the concentration at a level exceeding some critical value, otherwise the corrosion rate increases. Complexing organic agents do not show such hazardous behaviour. The very rapid corrosion of titanium and zirconium in fluoride media may be lessened by complexing the fluoride ions. Though rarely encountered, localized corrosion may be avoided by using inhibitors. In some cases good corrosion inhibitors for titanium are dissolution accelerators for zirconium. (author)

Properties of titanium-alloyed DLC layers for medical applications

Science.gov (United States)

Joska, Ludek; Fojt, Jaroslav; Cvrcek, Ladislav; Brezina, Vitezslav

2014-01-01

DLC-type layers offer a good potential for application in medicine, due to their excellent tribological properties, chemical resistance, and bio-inert character. The presented study has verified the possibility of alloying DLC layers with titanium, with coatings containing three levels of titanium concentration prepared. Titanium was present on the surface mainly in the form of oxides. Its increasing concentration led to increased presence of titanium carbide as well. The behavior of the studied systems was stable during exposure in a physiological saline solution. Electrochemical impedance spectra practically did not change with time. Alloying, however, changed the electrochemical behavior of coated systems in a significant way: from inert surface mediating only exchange reactions of the environment in the case of unalloyed DLC layers to a response corresponding rather to a passive surface in the case of alloyed specimens. The effect of DLC layers alloying with titanium was tested by the interaction with a simulated body fluid, during which precipitation of a compound containing calcium and phosphorus - basic components of the bone apatite - occurred on all doped specimens, in contrast to pure DLC. The results of the specimens' surface colonization with cells test proved the positive effect of titanium in the case of specimens with a medium and highest content of this element. PMID:25093457

Synthesis of Titanium Oxycarbide from Titanium Slag by Methane-Containing Gas

Science.gov (United States)

Dang, Jie; Fatollahi-Fard, Farzin; Pistorius, Petrus Christiaan; Chou, Kuo-Chih

2018-02-01

In this study, reaction steps of a process for synthesis of titanium oxycarbide from titanium slag were demonstrated. This process involves the reduction of titanium slag by a methane-hydrogen-argon mixture at 1473 K (1200 °C) and the leaching of the reduced products by hydrofluoric acid near room temperature to remove the main impurity (Fe3Si). Some iron was formed by disproportionation of the main M3O5 phase before gaseous reduction started. Upon reduction, more iron formed first, followed by reduction of titanium dioxide to suboxides and eventually oxycarbide.

Carbonate effects on hexavalent uranium removal from water by nanocrystalline titanium dioxide

International Nuclear Information System (INIS)

Wazne, Mahmoud; Meng, Xiaoguang; Korfiatis, George P.; Christodoulatos, Christos

2006-01-01

A novel nanocrystalline titanium dioxide was used to treat depleted uranium (DU)-contaminated water under neutral and alkaline conditions. The novel material had a total surface area of 329 m 2 /g, total surface site density of 11.0 sites/nm 2 , total pore volume of 0.415 cm 3 /g and crystallite size of 6.0 nm. It was used in batch tests to remove U(VI) from synthetic solutions and contaminated water. However, the capacity of the nanocrystalline titanium dioxide to remove U(VI) from water decreased in the presence of inorganic carbonate at pH > 6.0. Adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, and surface charge measurements were used to investigate the causes of the reduced capacity. The surface charge and the FTIR measurements suggested that the adsorbed U(VI) species was not complexed with carbonate at neutral pH values. The decreased capacity of titanium dioxide to remove U(VI) from water in the presence of carbonate at neutral to alkaline pH values was attributed to the aqueous complexation of U(VI) by inorganic carbonate. The nanocrystalline titanium dioxide had four times the capacity of commercially available titanium dixoide (Degussa P-25) to adsorb U(VI) from water at pH 6 and total inorganic carbonate concentration of 0.01 M. Consequently, the novel material was used to treat DU-contaminated water at a Department of Defense (DOD) site

Surface-Induced Hybridization between Graphene and Titanium

Energy Technology Data Exchange (ETDEWEB)

Hsu, Allen L. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Koch, Roland J. [Technische Universitat, Chemnitz (Germany); Ong, Mitchell T. [Stanford Univ., CA (United States); Fang, Wenjing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Hofmann, Mario [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Kim, Ki Kang [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Seyller, Thomas [Technische Universitat, Chemnitz (Germany); Dresselhaus, Mildred S. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Reed, Evan J. [Stanford Univ., CA (United States); Kong, Jing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Palacios, Tomás [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)

2014-08-26

Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many of these applications are limited by the complex interactions between carbon-based materials and metals. In this work, we experimentally investigate the structural interactions between graphene and transition metals such as palladium (Pd) and titanium (Ti), which have been confirmed by density functional simulations. We find that the adsorption of titanium on graphene is more energetically favorable than in the case of most metals, and density functional theory shows that a surface induced p-d hybridization occurs between atomic carbon and titanium orbitals. This strong affinity between the two materials results in a short-range ordered crystalline deposition on top of graphene as well as chemical modifications to graphene as seen by Raman and X-ray photoemission spectroscopy (XPS). This induced hybridization is interface-specific and has major consequences for contacting graphene nanoelectronic devices as well as applications toward metal-induced chemical functionalization of graphene.

Titanium by design: TRIP titanium alloy

Science.gov (United States)

Tran, Jamie

Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

Titanium Analysis of Ilmenite Bangka by Spectrophotometric Method Using Perhidrol

International Nuclear Information System (INIS)

Rusydi-S

2004-01-01

Determination of titanium by spectrofotometric method using perhydrol has been done. The purpose of experiment is to find out the condition of titanium analysis of ilmenite by spectrophotometric method. The experiment parameter e c. analysis condition include the Ti-perhydrol complex spectrum, acidity of complex, perhydrol concentration, linearity, influence of anion, limit detection, interfere elements, application of the method using 40 SRM Standard and analysis for ilmenite samples. Result of experiments are spectrum of Ti-perhydrol complex at 410 nm, acidity of complex is the H 2 SO 4 2 M, perhydrol concentration is 0,24 %, the curve calibration is linier at 1-80 ppm, anion of PO 4 , NO 3 , Cl, CO 3 not be influence until 2000 ppm, limit detection is 0,30 ppm and Mo, V is interfere. The method which was aplicated to 40 SRM standard, shown that the content of Ti is 1580 ppm while the standard is 1600 ppm, and the content of Ti from ilmenite high grade samples is 31,46 % and low grade is 13,55 %. (author)

Corrosion of titanium and titanium alloys in spent fuel repository conditions - literature review

International Nuclear Information System (INIS)

Aho-Mantila, I.; Haenninen, H.; Aaltonen, P.; Taehtinen, S.

1985-03-01

The spent nuclear fuel is planned to be disposed in Finnish bedrock. The canister of spent fuel in waste repository is one barrier to the release of radionuclides. It is possible to choose a canister material with a known, measurable corrosion rate and to make it with thickness allowing corrosion to occur. The other possibility is to use a material which is nearly immune to general corrosion. In this second category there are titanium and titanium alloys which exhibit a very high degree of resistance to general corrosion. In this literature study the corrosion properties of unalloyed titanium, titanium alloyed with palladium and titanium alloyed with molybdenum and nickel are reviewed. The two titanium alloys own in addition to the excellent general corrosion properties outstanding properties against localized corrosion like pitting or crevice corrosion. Stress corrosion cracking and corrosion fatique of titanium seem not to be a problem in the repository conditions, but the possibilities of delayed cracking caused by hydrogen should be carefully appreciated. (author)

Synthesis of titanium oxide nanoparticles using DNA-complex as template for solution-processable hybrid dielectric composites

Energy Technology Data Exchange (ETDEWEB)

Ramos, J.C. [Center for Sustainable Materials Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, OR (United States); Mejia, I.; Murphy, J.; Quevedo, M. [Department of Materials Science and Engineering, University of Texas at Dallas, Dallas, TX (United States); Garcia, P.; Martinez, C.A. [Engineering and Technology Institute, Autonomous University of Ciudad Juarez, Ciudad Juarez, Chihuahua (Mexico)

2015-09-15

Highlights: • We developed a synthesis method to produce TiO{sub 2} nanoparticles using a DNA complex. • The nanoparticles were anatase phase (~6 nm diameter), and stable in alcohols. • Composites showed a k of 13.4, 4.6 times larger than the k of polycarbonate. • Maximum processing temperature was 90 °C. • Low temperature enables their use in low-voltage, low-cost, flexible electronics. - Abstract: We report the synthesis of TiO{sub 2} nanoparticles prepared by the hydrolysis of titanium isopropoxide (TTIP) in the presence of a DNA complex for solution processable dielectric composites. The nanoparticles were incorporated as fillers in polycarbonate at low concentrations (1.5, 5 and 7 wt%) to produce hybrid dielectric films with dielectric constant higher than thermally grown silicon oxide. It was found that the DNA complex plays an important role as capping agent in the formation and suspension stability of nanocrystalline anatase phase TiO{sub 2} at room temperature with uniform size (∼6 nm) and narrow distribution. The effective dielectric constant of spin-cast polycarbonate thin-films increased from 2.84 to 13.43 with the incorporation of TiO{sub 2} nanoparticles into the polymer host. These composites can be solution processed with a maximum temperature of 90 °C and could be potential candidates for its application in low-cost macro-electronics.

Engineering a novel material: Nanometric titanium carbide particles in a matrix of carbon nanotubes

CERN Document Server

BADIE, Sylvain

2015-01-01

New physics studies at ISOLDE are motivated by new beams available, especially beams of exotic nuclei located at the frontier of the nuclear chart. Such beams are often short lived (in the order of milliseconds) and decay before they can be extracted from the target material, where typical diffusion times are in the order of seconds or more. Novel nanostructured and nanocomposite target materials have been developed to increase the release efficiency by reducing the diffusion paths and so the diffusion times, allowing ISOLDE to deliver new and more intense beams of exotic nuclei. 35Ca (25 ms half-life) was attempted by developing a titanium carbide and carbon black nanocomposite, but such isotope could not be extracted. A different production method with different precursors - titanium oxide and multiwall carbon nanotubes - is here proposed and expected to yield a target material which will increase the release rates of such isotope. A novel material, very porous, consisting of titanium carbide particles disp...

Clinical experience of titanium cerebral aneurysm clips. Evaluation of artifact of CT and MRI

International Nuclear Information System (INIS)

Ninomiya, Takashi; Kato, Yoko; Sano, Hirotoshi

1996-01-01

The titanium aneurysm clips manufactured by AESCULAP Company are expected to be useful, not only for clinical applications, but also for reducing artifacts in post-operative CT and MRI. We carried out an investigation of the behavior of the new Yasargil titanium clips in a 1.5T MR imager. The new titanium clips showed considerably smaller clip-induced MR and CT artifacts than phynox and elgiloy clips. No movement of the titanium clips was seen by introducing them to the MR imager. Subsequent to these experimental studies, we applied titanium clips to 25 cerebral aneurysms. Post-operative CT, especially helical scanning CT and MR showed minimal artifacts, leading to the conclusion that the titanium clips are better than the other types of clips for the evaluation of post-operative neuroradiological images. (author)

Chitosan patterning on titanium alloys

OpenAIRE

Gilabert Chirivella, Eduardo; Pérez Feito, Ricardo; Ribeiro, Clarisse; Ribeiro, Sylvie; Correia, Daniela; González Martin, María Luisa; Manero Planella, José María; Lanceros Méndez, Senentxu; Gallego Ferrer, Gloria; Gómez Ribelles, José Luis

2017-01-01

Titanium and its alloys are widely used in medical implants because of their excellent properties. However, bacterial infection is a frequent cause of titanium-based implant failure and also compromises its osseointegration. In this study, we report a new simple method of providing titanium surfaces with antibacterial properties by alternating antibacterial chitosan domains with titanium domains in the micrometric scale. Surface microgrooves were etched on pure titanium disks at i...

Friction behavior and other material properties of nickel-titanium and titanium-molybdenum archwires following electrochemical surface refinement.

Science.gov (United States)

Meier, Miriam Julia; Bourauel, Christoph; Roehlike, Jan; Reimann, Susanne; Keilig, Ludger; Braumann, Bert

2014-07-01

The aim of this work was to investigate whether electrochemical surface treatment of nickel-titanium (NiTi) and titanium-molybdenum (TiMo) archwires (OptoTherm and BetaTitan; Ortho-Dent Specials, Kisdorf, Germany) reduces friction inside the bracket-archwire complex. We also evaluated further material properties and compared these to untreated wires. The material properties of the surface-treated wires (Optotherm/LoFrix and BetaTitan/LoFrix) were compared to untreated wires made by the same manufacturer (see above) and by another manufacturer (Neo Sentalloy; GAC, Bohemia, NY, USA). We carried out a three-point bending test, leveling test, and friction test using an orthodontic measurement and simulation system (OMSS). In addition, a pure bending test was conducted at a special test station, and scanning electron micrographs were obtained to analyze the various wire types for surface characteristics. Finally, edge beveling and cross-sectional dimensions were assessed. Force losses due to friction were reduced by 10 percentage points (from 36 to 26%) in the NiTi and by 12 percentage points (from 59 to 47%) in the TiMo wire specimens. Most of the other material properties exhibited no significant changes after surface treatment. While the three-point bending tests revealed mildly reduced force levels in the TiMo specimens due to diameter losses of roughly 2%, these force levels remained almost unchanged in the NiTi specimens. Compared to untreated NiTi and TiMo archwire specimens, the surface-treated specimens demonstrated reductions in friction loss by 10 and 12 percentage points, respectively.

Corrosion behaviour and galvanic coupling of titanium and welded titanium in LiBr solutions

International Nuclear Information System (INIS)

Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D.

2007-01-01

Corrosion resistance and galvanic coupling of Grade 2 commercially pure titanium in its welded and non-welded condition were systematically analyzed in LiBr solutions. Galvanic corrosion was evaluated through two different methods: anodic polarization (according to the Mixed Potential Theory) and electrochemical noise (using a zero-resistance ammeter). Samples have been etched to study the microstructure. The action of lithium chromate as corrosion inhibitor has been evaluated. Titanium and welded titanium showed extremely low corrosion current densities and elevated pitting potential values (higher than 1 V). The results of both methods, anodic polarization and electrochemical noise, showed that the welded titanium was always the anodic element of the pair titanium-welded titanium, so that its corrosion resistance decreases due to the galvanic effect

High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy

International Nuclear Information System (INIS)

Hung, Le Thanh; Van Nong, Ngo; Snyder, G. Jeffrey; Viet, Man Hoang; Balke, Benjamin; Han, Li; Stamate, Eugen; Linderoth, Søren; Pryds, Nini

2015-01-01

Highlights: • p-type segmented leg of oxide and half-Heusler was for the first time demonstrated. • The maximum conversion efficiency reached a value of about 5%. • The results are among the highest reported values so far for oxide-based legs. • Oxide-based segmented leg is very promising for generating electricity. - Abstract: In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca 2.8 Lu 0.15 Ag 0.05 Co 4 O 9+δ and half-Heusler Ti 0.3 Zr 0.35 Hf 0.35 CoSb 0.8 Sn 0.2 alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, ΔT, with the hot side temperature up to 1153 K. At ΔT ≈ 756 K, the maximum conversion efficiency reached a value of ∼5%, which is about 65% of that expected from the materials without parasitic losses. The long-term stability investigation for two weeks at the hot and cold side temperatures of 1153/397 K shows that the segmented leg has good durability as a result of stable and low electrical resistance contacts

Electrowinning molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 3 Rationale – Titanium Cost Build-up Material Cost Ilmenite $0.27/kg Ti sponge Titanium slag $0.75/kg Ti Sponge TiCl4 and TiO2 $3....10/kg Ti Sponge Ti Sponge raw materials costs $5.50/kg Ti Sponge Total Ti Sponge cost $9-$11/kg Ti Sponge Ti ingot $15-17/kg Ti Aluminium $1.7/kg Al Supporting the Manufacturing and Materials Industry in its quest for global competitivenessorting...

Trojan-Like Internalization of Anatase Titanium Dioxide Nanoparticles by Human Osteoblast Cells.

Science.gov (United States)

Ribeiro, A R; Gemini-Piperni, S; Travassos, R; Lemgruber, L; Silva, R C; Rossi, A L; Farina, M; Anselme, K; Shokuhfar, T; Shahbazian-Yassar, R; Borojevic, R; Rocha, L A; Werckmann, J; Granjeiro, J M

2016-03-29

Dentistry and orthopedics are undergoing a revolution in order to provide more reliable, comfortable and long-lasting implants to patients. Titanium (Ti) and titanium alloys have been used in dental implants and total hip arthroplasty due to their excellent biocompatibility. However, Ti-based implants in human body suffer surface degradation (corrosion and wear) resulting in the release of metallic ions and solid wear debris (mainly titanium dioxide) leading to peri-implant inflammatory reactions. Unfortunately, our current understanding of the biological interactions with titanium dioxide nanoparticles is still very limited. Taking this into consideration, this study focuses on the internalization of titanium dioxide nanoparticles on primary bone cells, exploring the events occurring at the nano-bio interface. For the first time, we report the selective binding of calcium (Ca), phosphorous (P) and proteins from cell culture medium to anatase nanoparticles that are extremely important for nanoparticle internalization and bone cells survival. In the intricate biological environment, anatase nanoparticles form bio-complexes (mixture of proteins and ions) which act as a kind of 'Trojan-horse' internalization by cells. Furthermore, anatase nanoparticles-induced modifications on cell behavior (viability and internalization) could be understand in detail. The results presented in this report can inspire new strategies for the use of titanium dioxide nanoparticles in several regeneration therapies.

Ductile and brittle transition behavior of titanium alloys in ultra-precision machining.

Science.gov (United States)

Yip, W S; To, S

2018-03-02

Titanium alloys are extensively applied in biomedical industries due to their excellent material properties. However, they are recognized as difficult to cut materials due to their low thermal conductivity, which induces a complexity to their deformation mechanisms and restricts precise productions. This paper presents a new observation about the removal regime of titanium alloys. The experimental results, including the chip formation, thrust force signal and surface profile, showed that there was a critical cutting distance to achieve better surface integrity of machined surface. The machined areas with better surface roughness were located before the clear transition point, defining as the ductile to brittle transition. The machined area at the brittle region displayed the fracture deformation which showed cracks on the surface edge. The relationship between depth of cut and the ductile to brittle transaction behavior of titanium alloys in ultra-precision machining(UPM) was also revealed in this study, it showed that the ductile to brittle transaction behavior of titanium alloys occurred mainly at relatively small depth of cut. The study firstly defines the ductile to brittle transition behavior of titanium alloys in UPM, contributing the information of ductile machining as an optimal machining condition for precise productions of titanium alloys.

Characterization of the titanium Kβ spectral profile

International Nuclear Information System (INIS)

Chantler, C T; Smale, L F; Kinnane, M N; Illig, A J; Kimpton, J A; Crosby, D N

2013-01-01

Transition metals have Kα and Kβ characteristic radiation possessing complex asymmetric spectral profiles. Instrumental broadening normally encountered in x-ray experiments shifts features of profiles used for calibration, such as peak energy, by many times the quoted accuracies. We measure and characterize the titanium Kβ spectral profile. The peak energy of the titanium Kβ spectral profile is found to be 4931.966 ± 0.022 eV prior to instrumental broadening. This 4.5 ppm result decreases the uncertainty over the past literature by a factor of 2.6 and is 2.4 standard deviations from the previous standard. The spectrum is analysed and the resolution-free lineshape is extracted and listed for use in other experiments. We also incorporate improvement in analysis applied to earlier results for V Kβ. (paper)

Performance test of twised-wired titanium evaporators for in-situ Tic deposition

International Nuclear Information System (INIS)

Inagawa, Konosuke; Abe, Tetsuya; Hiroki, Seiji; Obara, Kenjiro; Murakami, Yoshio

1984-06-01

In order to establish the titanium evaporation source for in-situ TiC deposition, performance test has been made for several types of twisted-wired, ohmic-heating titanium evaporators. The evaporator which exhibited the best performance consists of three tungsten wires twisted as the core of the composite, three titanium wires and a molybdenum wire densely wound around the core, and a thin tungsten wire coarsely wound at the outermost side of the composite. The molybdenum wire around the core plays an important role in wetting the core surface uniformly with the melt of titanium. The tungsten wire at the outermost side prevents the molten titanium from dropping to the inside wall of the vacuum vessel. A typical size of the evaporator is 4 mm in diameter and 140 mm in length. In this case 2--2.5g of titanium, which corresponds to 70 - 80 % of charged amount (3.2g), can be evaporated at a rate of about 0.14 g/min. On the basis of the experimental results, the applicability of the evaporator to JT-60 is discussed. (author)

OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

OpenAIRE

I. I. Kuzhelivsky; M. A. Akselrov; L. A. Sitko

2015-01-01

The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

Polypropylene Nanocomposites Obtained by In Situ Polymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

Directory of Open Access Journals (Sweden)

Paula Zapata

2012-01-01

Full Text Available Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind2ZrCl2/methylaluminoxane (MAO system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind2ZrCl2/(MAO directly into the reactor, and in route 2 the metallocene rac-Et(Ind2ZrCl2 was supported on silica nanospheres pretreated with (MAO. SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2.

Spatiotemporal Characteristics of QRS Complexes Enable the Diagnosis of Brugada Syndrome Regardless of the Appearance of a Type 1 ECG.

Science.gov (United States)

Guillem, Maria S; Climent, Andreu M; Millet, José; Berne, Paola; Ramos, Rafael; Brugada, Josep; Brugada, Ramon

2016-05-01

The diagnosis of Brugada syndrome based on the ECG is hampered by the dynamic nature of its ECG manifestations. Brugada syndrome patients are only 25% likely to present a type 1 ECG. The objective of this study is to provide an ECG diagnostic criterion for Brugada syndrome patients that can be applied consistently even in the absence of a type 1 ECG. We recorded 67-lead body surface potential maps from 94 Brugada syndrome patients and 82 controls (including right bundle branch block patients and healthy individuals). The spatial propagation direction during the last r' wave and the slope at the end of the QRS complex were measured and compared between patients groups. Receiver-operating characteristic curves were constructed for half of the database to identify optimal cutoff values; sensitivity and specificity for these cutoff values were measured in the other half of the database. A spontaneous type 1 ECG was present in only 30% of BrS patients. An orientation in the sagittal plane ECG recordings can enable a robust identification of BrS even without the presence of a type 1 ECG. © 2016 Wiley Periodicals, Inc.

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

OpenAIRE

Jeena, Vineet; Robinson, Ross S

2009-01-01

Summary The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding ?-hydroxyketones.

Oxochloroalkoxide of the Cerium (IV and Titanium (IV as oxides precursor

Directory of Open Access Journals (Sweden)

Machado Luiz Carlos

2002-01-01

Full Text Available The Cerium (IV and Titanium (IV oxides mixture (CeO2-3TiO2 was prepared by thermal treatment of the oxochloroisopropoxide of Cerium (IV and Titanium (IV. The chemical route utilizing the Cerium (III chloride alcoholic complex and Titanium (IV isopropoxide is presented. The compound Ce5Ti15Cl16O30 (iOPr4(OH-Et15 was characterized by elemental analysis, FTIR and TG/DTG. The X-ray diffraction patterns of the oxides resulting from the thermal decomposition of the precursor at 1000 degreesC for 36 h indicated the formation of cubic cerianite (a = 5.417Å and tetragonal rutile (a = 4.592Å and (c = 2.962 Å, with apparent crystallite sizes around 38 and 55nm, respectively.

The use of titanium dioxide micro-columns to selectively isolate phosphopeptides from proteolytic digests

DEFF Research Database (Denmark)

Thingholm, Tine E; Larsen, Martin R

2009-01-01

Titanium dioxide has very high affinity for phosphopeptides and it has become an efficient alternative to already existing methods for phosphopeptide enrichment from complex samples. Peptide loading in a highly acidic environment in the presence of 2,5-dihydroxybenzoic acid (DHB), phthalic acid......, or glycolic acid has been shown to improve selectivity significantly by reducing unspecific binding from nonphosphorylated peptides. The enriched phosphopeptides bound to the titanium dioxide are subsequently eluted from the micro-column using an alkaline buffer. Titanium dioxide chromatography is extremely...... tolerant towards most buffers used in biological experiments. It is highly robust and as such it has become one of the methods of choice in large-scale phospho-proteomics. Here we describe the protocol for phosphopeptide enrichment using titanium dioxide chromatography followed by desalting...

Development of a database system for operational use in the selection of titanium alloys

Science.gov (United States)

Han, Yuan-Fei; Zeng, Wei-Dong; Sun, Yu; Zhao, Yong-Qing

2011-08-01

The selection of titanium alloys has become a complex decision-making task due to the growing number of creation and utilization for titanium alloys, with each having its own characteristics, advantages, and limitations. In choosing the most appropriate titanium alloys, it is very essential to offer a reasonable and intelligent service for technical engineers. One possible solution of this problem is to develop a database system (DS) to help retrieve rational proposals from different databases and information sources and analyze them to provide useful and explicit information. For this purpose, a design strategy of the fuzzy set theory is proposed, and a distributed database system is developed. Through ranking of the candidate titanium alloys, the most suitable material is determined. It is found that the selection results are in good agreement with the practical situation.

Aluminium effect on the physical properties of titanium

International Nuclear Information System (INIS)

Nazimov, O.P.; Il'in, A.A.; Zvonova, L.N.

1977-01-01

The effect of aluminium on the physical properties of titanium was investigated. Within the framework of the configuration model of matter it is shown that a change in physical properties with an aluminium content of up to 7.5 wt.% in alloys depends on the phase composition and electron structure. In interacting with titanium, aluminium exhibits acceptor properties, causing d→s electron transitions. The electrons which have shifted to the s-state are partly collectivized and partly localized into quasistable sp 3 configurations, with the resulting increase of the interatomic forces. An intensification of d→s transitions in alloying of titanium with aluminium stabilizes the α-phase. Predominance of d 1 configurations in the intermediate spectrum in the region of the α-solution increases the ratio of the axes of the HCP lattice and determines the electron type of conduction of alloys of the Ti-Al system

Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

DEFF Research Database (Denmark)

Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

2017-01-01

Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energy...

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

International Nuclear Information System (INIS)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang; Gao, Ziwei

2015-01-01

A successive anchoring of Ti(NMe 2 ) 4 , cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, 13 C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, 13 C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

Energy Technology Data Exchange (ETDEWEB)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang, E-mail: gfzhang@snnu.edu.cn; Gao, Ziwei, E-mail: zwgao@snnu.edu.cn

2015-01-15

A successive anchoring of Ti(NMe{sub 2}){sub 4}, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, {sup 13}C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, {sup 13}C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated.

Gamma titanium aluminide production using the Induction Skull Melting (ISM) process

International Nuclear Information System (INIS)

Reed, S.

1995-01-01

Since 1985, more than 2,000 titanium aluminide heats have been produced using the Induction Skull Melting (ISM) process. The history of ISM/Gamma production will be discussed in this paper. Gamma titanium aluminide processing with Induction Skull Melting offers many advantages over other types of reactive alloy melting methods. These advantages will be discussed as well as drawbacks. Also, potential markets and applications for ISM/Gamma will be presented

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

Science.gov (United States)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang; Gao, Ziwei

2015-01-01

A successive anchoring of Ti(NMe2)4, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1‧-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, 13C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

Science.gov (United States)

Smeets, Ralf; Schöllchen, Maximilian; Gauer, Tobias; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-02-01

To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

Directory of Open Access Journals (Sweden)

I. I. Kuzhelivsky

2015-01-01

Full Text Available The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

A comparative study of gold UCLA-type and CAD/CAM titanium implant abutments

Science.gov (United States)

Park, Ji-Man; Lee, Jai-Bong; Heo, Seong-Joo

2014-01-01

PURPOSE The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of ±0.1 µm at 50 points. RESULTS Initial detorque values of milled abutment were significantly higher than those of cast abutment (P.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (Pabutment group and the cast abutment group after cyclic loading. CONCLUSION In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment. PMID:24605206

Determination of quercetin using a photo-electrochemical sensor modified with titanium dioxide and a platinum(II)-porphyrin complex

International Nuclear Information System (INIS)

Tian, Li; Wang, Binbin; Chen, Ruizhan; Gao, Ye; Chen, Yanling; Li, Tianjiao

2015-01-01

A glassy carbon electrode (GCE) was modified with a film containing titanium dioxide and a Pt(II)-porphyrin complex, and its response to quercetin was investigated employing cyclic voltammetry and chronoamperometry. The oxidation current caused by quercetin is largely enhanced under UV illumination. The effects of pH value, mass of TiO 2 in the film, UV illumination time and applied potential were studied. Under optimized conditions, the peak current at a typically applied voltage of +0.4 V depends linearly on the concentration of quercetin in the 0.002 to 50 mg L −1 range. The detection limit (at an SNR of 3) is 0.8 μg L −1 . The method was successfully applied to the determination of quercetin in (spiked) samples of tea and apple juice. (author)

Dense and porous titanium substrates with a biomimetic calcium phosphate coating

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, A.A., E-mail: aantunesr@yahoo.com.br [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil); Balestra, R.M. [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil); Rocha, M.N. [Metallurgical and Materials Engineering Program, COPPE, Federal University of Rio de Janeiro, P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Peripolli, S.B. [Materials Metrology Division, National Institute of Metrology, Normalization and Quality, No. 50 Nossa Senhora das Gracas Street, Building 3, 25250-020 Duque de Caxias, RJ (Brazil); Andrade, M.C. [Polytechnic Institute of Rio de Janeiro, Rio de Janeiro State University, s/n, Alberto Rangel Street, 28630-050 Nova Friburgo, RJ (Brazil); Pereira, L.C. [Metallurgical and Materials Engineering Program, COPPE, Federal University of Rio de Janeiro, P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Oliveira, M.V. [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil)

2013-01-15

Highlights: Black-Right-Pointing-Pointer A biomimetic coating method with simplified solution is proposed. Black-Right-Pointing-Pointer Titanium substrates are submitted to chemical and heat treatments. Black-Right-Pointing-Pointer Titanium substrates are coated with biocompatible calcium phosphate phases. Black-Right-Pointing-Pointer The simplified solution shows potential to be applied as a coating technique. - Abstract: The present work studied a biomimetic method using a simplified solution (SS) with calcium and phosphorus ions for coating titanium substrates, in order to improve their bioactivity. Commercially pure titanium dense sheet, microporous and macroporous titanium samples, both produced by powder metallurgy, were treated in NaOH solution followed by heat-treating and immersed in SS for 7, 14 or 21 days. The samples characterization was performed by quantitative metallographic analysis, confocal scanning optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and low angle X-ray diffraction. The results showed coatings with calcium phosphate precipitation in all samples, with globular or plate-like morphology, typical of hydroxyapatite and octacalcium phosphate, respectively, indicating that the solution (SS) has potential for coating titanium substrates. In addition, the different surfaces of substrates had an effect on the formed calcium phosphate phase and thickness of coatings, depending on the substrate type and imersion time in the simplified solution.

Studies in group IV organometallic chemistry XXX. Synthesis of compounds containing tin---titanium and tin---zirconium bonds

NARCIS (Netherlands)

Creemers, H.M.J.C.; Verbeek, F.; Noltes, J.G.

1968-01-01

Starting from the tetrakis(diethylamino) derivatives of titanium and zirconium and pheyltin hydrides six intermetalic compounds contianing up to nine tin and titanium(or zirconium) atoms have been obtained by hydrostannolysis type reactions.

A study of magnetoplumbite-type (M-type) cobalt-titanium-substituted barium ferrite, BaCoxTixFe12-2xO19 (x = 1-6)

International Nuclear Information System (INIS)

Teh, G.B.; Saravanan, N.; Jefferson, D.A.

2007-01-01

Cobalt(II)-titanium(IV)-substituted barium ferrite forming the chemical formula of BaCo x Ti x Fe 12-2x O 19 (x = 1-6) have been investigated using X-ray diffraction spectroscopy (XRD), Superconducting Quantum Interference Device (SQUID) and high-resolution transmission electron microscopy (HRTEM). The specimen of magnetoplumbite (M-type) Co-Ti-substituted BaFe 12 O 19 were synthesised via sol-gel method using ethylene glycol as precursor. Significant increase in line broadening of the XRD patterns were observed indicating the decrease of particle sizes due to the Co(II)-Ti(IV) substitution. BaCo 3 Ti 3 Fe 6 O 19 showed the highest coercivity but moderate saturation and remnant magnetisations. HRTEM imaging showed that Co(II)-Ti(IV) substitution in the system of BaCo x Ti x Fe 12-2x O 19 (x = 1-6) produced no drastic change in the structure of the M-type ferrites. Most of the M-types crystals examined by HRTEM displayed a long axis perpendicular to the c-axis of the M-type structure. Disordered crystals showing the intergrowth between Co-Ti-substituted barium ferrite and the spinel-structured iron oxide were detected

Titanium Isotopes Provide Clues to Lunar Origin

Science.gov (United States)

Taylor, G. J.

2012-05-01

The idea that the Moon formed as the result of the giant impact of a Mars-sized impactor with the still-growing Earth explains two central facts about the Earth-Moon system: its total angular momentum (Earth's spin and the Moon's orbital motion), and the sizes of the metallic cores of the Earth (large) and Moon (tiny). This gives cosmochemists some confidence in the hypothesis, but they would greatly appreciate additional compositional tests. One undisputed point is the identical abundance of the three oxygen isotopes in Earth and Moon. Junjun Zhang and colleagues at the University of Chicago (USA) and the University of Bern (Switzerland) have added another isotopic system to the cosmochemical testing tool kit, titanium isotopes. They find that the ratio of titanium-50 to titanium-47 is identical in Earth and Moon to within four parts per million. In contrast, other solar system materials, such as carbonaceous chondrites, vary by considerably more than this-- up to 150 times as much. The identical oxygen and titanium isotopic compositions in Earth and Moon are surprising in light of what we think we know about planet formation and formation of the Moon after a giant impact. The variations in oxygen and titanium isotopes among meteorite types suggest that it is unlikely that the Moon-forming giant impactor would have had the same isotopic composition as the Earth. Simulations show that the Moon ends up constructed mostly (40-75%) from the impactor materials. Thus, the Moon ought to have different isotopic composition than does Earth. The isotopes might have exchanged in the complicated, messy proto-lunar disk (as has been suggested for oxygen isotopes), making them the same. However, Zhang and colleagues suggest that this exchange is unlikely for a refractory element like titanium. Could the impact simulations be greatly overestimating the contributions from the impactor? Was the mixing of building-block materials throughout the inner solar system much less than

[Effect of sintering gold paste coating on the bonding strength of pure titanium and three low-fusing porcelains].

Science.gov (United States)

Zhang, Ya-li; Luo, Xiao-ping; Zhou, Li

2012-05-01

To study the effect of sintering gold paste coating of pure titanium on the adhesion of three porcelains following the protocol ISO 9693, and to investigate the titanium-porcelains interfaces. Sixty machined pure titanium samples were prepared in a rectangular shape according to ISO 9693 and divided equally into six groups. Half of the strips were coated with gold paste (Deckgold) and sintered. Three ultra-low-fusing dental porcelains (I: Initial Ti, S: Super porcelain Ti-22, T: TitanKeramik) were fused onto the titanium surfaces. A thin layer of bonding agent was only applied on the surfaces of uncoated gold specimens. The interface of the porcelain and titanium was observed with a field emission scanning electron microscope (FE-SEM) after metallographic preparation and sputtered with a very thin carbon layer of the embedded titanium-porcelain interface. After three-point bending test was performed, optical stereomicroscope was used to characterize the titanium-porcelains adhesion and determine the mode of failure. FE-SEM illustrated intermetallic compounds of Au-Ti formed with some visible microcracks in the gold layer and the interface of gold layer and ceramic. All the uncoated gold titanium-porcelain system showed predominately adhesive fracture at the titanium oxidation, whereas the failure modes in all gold coated systems were cohesive and adhesive, mainly cohesive. The three-point-bending test showed that the bonding strength of GS and GI groups [(37.08 ± 4.32) and (36.20 ± 2.40) MPa] were higher than those in uncoated groups [(31.56 ± 3.74) and (30.88 ± 2.60) MPa, P 0.05). The gold paste intermediate coatings can improve bond strengths of Super porcelain Ti-22 system and Initial Ti system, which have potential applications in clinical fields.

A homologous series of regioselectively tetradeprotonated group 8 metallocenes: new inverse crown ring compounds synthesized via a mixed sodium-magnesium tris(diisopropylamide) synergic base.

Science.gov (United States)

Andrikopoulos, Prokopis C; Armstrong, David R; Clegg, William; Gilfillan, Carly J; Hevia, Eva; Kennedy, Alan R; Mulvey, Robert E; O'Hara, Charles T; Parkinson, John A; Tooke, Duncan M

2004-09-22

Subjecting ferrocene, ruthenocene, or osmocene to the synergic amide base sodium-magnesium tris(diisopropylamido) affords a unique homologous series of metallocene derivatives of general formula [(M(C(5)H(3))(2))Na(4)Mg(4)(i-Pr(2)N)(8)] (where M = Fe (1), Ru (2), or Os (3)). X-ray crystallographic studies of 1-3 reveal a common molecular "inverse crown" structure comprising a 16-membered [(NaNMgN)(4)](4+) "host" ring and a metallocenetetraide [M(C(5)H(3))(2)](4-) "guest" core, the cleaved protons of which are lost selectively from the 1, 1', 3, and 3'-positions. Variable-temperature NMR spectroscopic studies indicate that 1, 2, and 3 each exist as two distinct interconverting conformers in arene solution, the rates of exchange of which have been calculated using coalescence and EXSY NMR measurements.

Rapid PMR determination of hydrogen in titanium hydride and dehydrogenated titanium powders

International Nuclear Information System (INIS)

Il'enko, V.S.; Demidenko, L.M.

1987-01-01

Proton magnetic resonance (PMR) enables determining hydrogen quantitatively in titanium hydride and dehydrogenated titanium powders without destroying the specimen and is also more informative than high-temperature extraction methods. PMR provides data on the electron-nuclear interactions and the activation energies for hydrogen diffusion while also providing conclusions on the forms and positives of the hydrogen in the lattice and the binding to the metal atoms. The authors have developed a rapid method for determining hydrogen in titanium hydride and dehydrogenated titanium powders which reduces the analysis time and improves the metrological characteristics. The authors use a YaMR-5535 spectrometer working at 40 MHz upgraded for use with hydrogen in solids. The authors used specimens of mass about 2 g ground to 0.1 mm powder

Polypropylene Nano composites Obtained by In Situ Polymerization Using Metallocenes Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

International Nuclear Information System (INIS)

Zapata, P.; Quijada, R.

2012-01-01

Polypropylene nano composites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind) 2 ZrCl 2 /methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind) 2 ZrCl 2 )/(MAO) directly into the reactor, and in route 2 the metallocenes rac-Et(Ind) 2 ZrCl 2 was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nano composites obtained by both routes had a slightly higher percent crystallinity and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nano composites obtained by the support system (route 2).

The molecular, electronic, bonding, and photophysical features of the [(c-Pt3)Tl(c-Pt3)]+ inorganic metallocenes.

Science.gov (United States)

Tsipis, Athanassios C; Gkekas, George N

2013-06-21

The molecular, electronic, bonding and photophysical properties of a series of inorganic metallocenes with the general formula {[Pt3(μ2-L)3(L')3]2(μ6-Tl)}(+) (L = CO, CH3CN, PH2, C6F5, or SO2 and L' = CO, PH3, CH3CN, C6F5) have been studied by means of DFT electronic structure calculations. The estimated Tl-cd distances between Tl(+) cations and the centroids (cd) of the trimetallic Pt3(μ2-L)3(L')3 {3 : 3 : 3} decks were found in the range 2.932-3.397 Å. The predicted bond dissociation energy, D0, of the (c-Pt3)···Tl(+) bonds was found to lie within the range -31.5 up to -77.5 kcal mol(-1) at the B3LYP/LANL2TZ(f)(Pt) ∪ 6-31G(d,p)(E) ∪ SRLC(Tl) level of theory. Most of the [(c-Pt3)Tl(c-Pt3)](+) inorganic metallocenes adopt a bend titanocene-like structure. The Localized Orbital Locator (LOL) contour maps along with the 3D contour plots of the Reduced Gradient Density (RDG) mirror the composite nature of the interaction of Tl(+) with the triangular Pt3 metallic ring cores consisting of electrostatic, covalent and dispersion interaction components. The Pt3···Tl(+)···Pt3 bonding mode was further validated by Energy Decomposition Analysis (EDA) calculations which demonstrated that the electrostatic and covalent components of the interaction contribute almost equally to the bonding interactions. Furthermore, Charge Decomposition Analysis (CDA) and Natural Bond Orbital Analysis (NBO) calculations indicated that charge transfer from the Tl(+) cation to the Pt3(0) {3 : 3 : 3} decks also occurs. The {[Pt3(μ2-L)3(L')3]2(μ6-Tl)}(+) sandwiches absorb in the UV-Vis region (300-500 nm) and emit in the visible-near IR region (600-1000 nm). The absorption bands are mainly of MLCT/MC character while phosphorescence is predicted to occur via the first triplet excited state, T1, since the spin density of this excited state could be described as a SOMO - 1/SOMO combination. Generally, no significant distortions occur upon excitation of these systems

Structural-performance testing of titanium-shell lead-matrix container MM2

Energy Technology Data Exchange (ETDEWEB)

Hosaluk, L. J.; Barrie, J. N.

1992-05-15

This report describes the hydrostatic structural-performance testing of a half-scale, titanium-shell, lead-matrix container (MM2) with a large, simulated volumetric casting defect. Mechancial behaviour of the container is assessed from extensive surface-strain measurements and post-test non-destructive and destructive examinations. Measured strain data are compared briefly with analytical results from a finite-element model of a previous test prototype, MM1, and with data generated by a finite-difference computer code. Finally, procedures are recommended for more detailed analytical modelling. (auth)

Complex manifolds in relativity

International Nuclear Information System (INIS)

Flaherty, E.J. Jr.

1975-01-01

Complex manifold theory is applied to the study of certain problems in general relativity. The first half of the work is devoted to the mathematical theory of complex manifold. Then a brief review of general relativity is given. It is shown that any spacetime admits locally an almost Hermitian structure, suitably modified to be compatible with the indefinite metric of spacetime. This structure is integrable if and only if the spacetime admits two geodesic and shearfree null congruences, thus in particular if the spacetime is type D vacuum or electrified. The structure is ''half-integrable'' in a suitable sense if and only if the spacetime admits one geodesic and shearfree null congruence, thus in particular for all algebraically special vacuum spacetimes. Conditions for the modified Hermitian spacetime to be Kahlerian are presented. The most general metric for such a modified Kahlerian spacetime is found. It is shown that the type D vacuum and electrified spacetimes are conformally related to modified Kahlerian spacetimes by a generally complex conformal factor. These latter are shown to possess a very rich structure, including the existence of Killing tensors and Killing vectors. A new ''explanation'' of Newman's complex coordinate transformations is given. It is felt to be superior to previous ''explanations'' on several counts. For example, a physical interpretation in terms of a symmetry group is given. The existence of new complex coordinate transformations is established: Nt is shown that any type D vacuum spacetime is obtainable from either Schwarzschild spacetime or ''C'' spacetime by a complex coordinate transformation. Finally, some related topics are discussed and areas for future work are outlined. (Diss. Abstr. Int., B)

X-ray absorption investigation of titanium oxynitride nanoparticles obtained from laser pyrolysis

International Nuclear Information System (INIS)

Simon, Pardis; March, Katia; Stéphan, Odile; Leconte, Yann; Reynaud, Cécile; Herlin-Boime, Nathalie; Flank, Anne-Marie

2013-01-01

Highlights: • Original Ti(O,N) nanoparticles with a TiO FCC structure were synthesized by laser pyrolysis. • EELS and XAS allows to demonstrate that the nanoparticles are a solid solution of N and O in Ti. • Upon heat treatment, oxidation occurs from the surface with survival of FCC contribution till 400 °C. • Optical properties (absorption in the visible range) can be adjusted through the control of oxidation state. - Abstract: This work presents a structural study by X-ray Absorption Spectroscopy (XAS) and Electron Energy-Loss Spectroscopy (EELS) of complex titanium oxynitride nanoparticles (Ti(O,N)), synthesized by laser pyrolysis from titanium tetraisopropoxide and ammonia as precursors. Previous structural characterizations obtained by XRD and XPS have shown that the nanoparticles present a TiO type face-centered cubic (FCC) structure but with three different oxidation degree for titanium. The synthesis of this kind of titanium oxide or oxynitride nanoparticles is very unusual. Moreover, their properties are highly dependent of their structure. EELS spectrum-imaging data were therefore used for mapping the different chemical species. These measurements reveal that the nanoparticles are composed of a FCC solid solution of nitrogen and oxygen in titanium. The local structure around Ti was then studied. XANES measurements show an absorption threshold corresponding to a global valence state between Ti 3+ and Ti 4+ , with a pre-edge structure characteristic of a mix between a face-centered cubic (FCC) structure and a disordered TiO 2 structure whereas the EXAFS signal is dominated by the contribution of the FCC structure. Oxidative heat-treatments have been performed from 250 to 450 °C in order to follow the transition towards the dioxide phase. EELS measurements show that the oxidation occurs from the surface of the nanoparticles. XAS show that this transition does not involve any other crystallographic phase than TiO 2 , mainly in its anatase form, and

Corrosion-resistant titanium nitride coatings formed on stainless steel by ion-beam-assisted deposition

International Nuclear Information System (INIS)

Baba, K.; Hatada, R.

1994-01-01

Titanium films 70nm thick were deposited on austenitic type 316L stainless steel substrates, and these specimens were irradiated with titanium ions of energy 70kV at a fluence of 1x10 17 ioncm -2 , using a metal vapor vacuum arc (MEVVA) IV metallic ion source at room temperature. After irradiation, titanium nitride (TiN) films were deposited by titanium evaporation and simultaneous irradiation by a nitrogen ion beam, with transport ratios of Ti to N atoms from 0.5 to 10.0 and an ion acceleration voltage of 2kV. The preferred orientation of the TiN films varied from left angle 200 right angle to left angle 111 right angle normal to the surface when the transport ratio was increased. With the help of Auger electron spectroscopy, interfacial mixing was verified. Nitrogen atoms were present in the state of titanium nitride for all transport ratios from 0.5 up to 10.0. However, the chemical bonding state of titanium changed from titanium nitride to the metallic state with increasing transport ratio Ti/N. The corrosion behavior was evaluated in an aqueous solution of sulfuric acid saturated with oxygen, using multisweep cyclic voltammetry measurements. Thin film deposition of pure titanium and titanium implantation prior to TiN deposition have beneficial effects on the suppression of transpassive chromium dissolution. ((orig.))

Organometallic Half-Sandwich Iridium Anticancer Complexes

Czech Academy of Sciences Publication Activity Database

Liu, Z.; Habtemariam, A.; Pizarro, A.M.; Fletcher, S.A.; Kisová, Anna; Vrána, Oldřich; Salassa, L.; Bruijnincx, P.C.A.; Clarkson, G.J.; Brabec, Viktor; Sadler, P. J.

2011-01-01

Roč. 54, č. 8 (2011), 3011-3026 ISSN 0022-2623 R&D Projects: GA ČR(CZ) GPP303/11/P047; GA ČR(CZ) GAP301/10/0598 Keywords : RUTHENIUM(II) ARENE COMPLEXES * CANCER-CELL CYTOTOXICITY * DNA-BINDING PROPERTIES Subject RIV: BO - Biophysics Impact factor: 5.248, year: 2011

Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Santilli do Nascimento Libanori, Gabriela [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Avansi Jr, Waldir [Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Arnold Schimidt, 13566-590 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN/LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, R. Francisco Degni, 55, Bairro Quitandinha, 14801-907 Araraquara, SP (Brazil)

2015-09-15

For this research, we studied the influence of titanium tetrachloride (TC) and titanium tetraisopropoxide (TTP) precursors on CaTiO{sub 3} (CTO) synthesis by employing a microwave-assisted hydrothermal (MAH) method regarding their respective short-, medium- and long-range features to determine if the use of different titanium precursors enhances the structural evolution of the material. The growth mechanism for the formation of the micro-cube-shaped CTO is proposed to obtain nanoparticle aggregation of self-assembly nanoplates. The disorder coupled to the oxygen vacancies of [TiO{sub 5}]–[TiO{sub 6}] in complex clusters in the CTO 1 powder and twists in bonding between the [TiO{sub 6}]–[TiO{sub 6}] complex clusters in the CTO 2 powder were mainly responsible for photoluminescent (PL) emission. - Highlights: • Different titanium precursors enhance the structural evolution of the material. • [TiO{sub 5}]–[TiO{sub 6}] and twists in bonding [TiO{sub 6}]–[TiO{sub 6}] were responsible for PL emission. • Micro-cube shaped was formed by nanoparticle aggregation of self-assembly nanoplates.

Diffusion complex layers of TiC-Ni-Mo type produced on steel during vacuum titanizing process combined with the electrolytic deposition

International Nuclear Information System (INIS)

Kasprzycka, E.; Krolikowski, A.

1999-01-01

Diffusion carbide layers produced on steel surface by means of vacuum titanizing process have been studied. A new technological process combining a vacuum titanizing with an electrolytic deposition of Ni-Mo alloy has been proposed to increase of corrosion resistance of carbide layers. The effect of preliminary electrolytic deposition of Ni-Mo alloy on the NC10 steel surface on the titanized layer structure and its corrosion resistance has ben investigated. As a result, diffusion complex layers of TiC-Ni-Mo type on NC10 steel surface have been obtained. An X-ray structural analysis of titanized surfaces on NC10 steel precovered with an electrolytic Ni-Mo alloy coating (70%Ni+30%Mo) revealed a presence of titanium carbide TiC, NiTi, MoTi and trace quantity of austenite. The image of the TiC-Ni-Mo complex layer on NC10 steel surface obtained by means of joined SEM+TEM method and diagrams of elements distribution in the layer diffusion zone have been shown. Concentration of depth profiles of Ti, Ni, Mo, Cr and Fe in the layer diffusion zone obtained by means of the joined EDS+TEM method are shown. Concentration depth profiles of Ti, Ni, Mo, Cr and Fe in the layer diffusion zone obtained by means of the X r ay microanalysis and microhardness of the layer are shown. An X-ray structural analysis of titanized surfaces on the NC10 steel, without Ni-Mo alloy layer, revealed only a substantial presence of titanium carbide TiC. For corrosion resistance tests the steel samples with various diffusion layers and without layers were used: (i) the TiC-Ni-Mo titanized complex layers on NC10 steel, (ii) the TiC titanized carbide layers on the NC10 steel, (iii) the NC10 steel without layers. Corrosion measurements of sample under test have been performed in 0.1 M H 2 SO 4 by means of potentiodynamic polarization and electrochemical impedance tests. It has been found that the corrosion resistance of titanized steel samples with the TiC and TiC-Ni-Mo layers is higher than for the steel

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

Porous titanium implants are widely used in dental, orthopaedic and otorhinolaryngology fields to improve implant integration to host tissue. A possible step further to improve the integration with the host is the incorporation of autologous cells in porous titanium structures via cell-laden hydrogels. Fast gelling hydrogels have advantageous properties for in situ applications such as localisation of specific cells and growth factors at a target area without dispersion. The ability to control the cell types in different regions of an implant is important in applications where the target tissue (i) has structural heterogeneity (multiple cell types with a defined spatial configuration with respect to each other); (ii) has physical property gradients essential for its function (such as in the case of osteochondral tissue transition). Due to their near immediate gelation, such gels can also be used for site-specific modification of porous titanium structures, particularly for implants which would face different tissues at different locations. Herein, we describe a step by step design of a model system: the model cell-laden gel-containing porous titanium implants in the form of titanium microbead/hydrogel (maleimide-dextran or maleimide-PVA based) microhybrids. These systems enable the determination of the effect of titanium presence on gel properties and encapsulated cell behaviour as a miniaturized version of full-scale implants, providing a system compatible with conventional analysis methods. We used a fibroblast/vascular endothelial cell co-cultures as our model system and by utilising single microbeads we have quantified the effect of gel microenvironment (degradability, presence of RGD peptides within gel formulation) on cell behaviour and the effect of the titanium presence on cell behaviour and gel formation. Titanium presence slightly changed gel properties without hindering gel formation or affecting cell viability. Cells showed a preference to move towards

Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

Energy Technology Data Exchange (ETDEWEB)

Du, Guodong [Iowa State Univ., Ames, IA (United States)

2003-01-01

In this work, the first examples of group 4 metalloporphyrin 1,2-diolato complexes were synthesized through a number of strategies. In general, treatment of imido metalloporphyrin complexes, (TTP)M=NR, (M = Ti, Zr, Hf), with vicinal diols led to the formation of a series of diolato complexes. Alternatively, the chelating pinacolate complexes could be prepared by metathesis of (TTP)MCl₂ (M = Ti, Hf) with disodium pinacolate. These complexes were found to undergo C-C cleavage reactions to produce organic carbonyl compounds. For titanium porphyrins, treatment of a titanium(II) alkyne adduct, (TTP)Ti(η²-PhC≡CPh), with aromatic aldehydes or aryl ketones resulted in reductive coupling of the carbonyl groups to produce the corresponding diolato complexes. Aliphatic aldehydes or ketones were not reactive towards (TTP)Ti(η²-PhC≡CPh). However, these carbonyl compounds could be incorporated into a diolato complex on reaction with a reactive precursor, (TTP)Ti[O(Ph)₂C(Ph)₂O] to provide unsymmetrical diolato complexes via cross coupling reactions. In addition, an enediolato complex (TTP)Ti(OCPhCPhO) was obtained from the reaction of (TTP)Ti(η²-PhC≡CPh) with benzoin. Titanium porphyrin diolato complexes were found to be intermediates in the (TTP)Ti=O-catalyzed cleavage reactions of vicinal diols, in which atmospheric oxygen was the oxidant. Furthermore, (TTP)Ti=O was capable of catalyzing the oxidation of benzyl alcohol and α-hydroxy ketones to benzaldehyde and α-diketones, respectively. Other high valent metalloporphyrin complexes also can catalyze the oxidative diol cleavage and the benzyl alcohol oxidation reactions with dioxygen. A comparison of Ti(IV) and Sn(IV) porphyrin chemistry was undertaken. While chelated diolato complexes were invariably obtained for titanium porphyrins on treatment with 1,2-diols, the reaction of vicinal diols with tin porphyrins gave a number of products, including mono

Chemical changes of titanium and titanium dioxide under electron bombardment

Directory of Open Access Journals (Sweden)

Romins Brasca

2007-09-01

Full Text Available The electron induced effect on the first stages of the titanium (Ti0 oxidation and titanium dioxide (Ti4+ chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+.

Complex hydrides for hydrogen storage

Science.gov (United States)

Zidan, Ragaiy

2006-08-22

A hydrogen storage material and process of forming the material is provided in which complex hydrides are combined under conditions of elevated temperatures and/or elevated temperature and pressure with a titanium metal such as titanium butoxide. The resulting fused product exhibits hydrogen desorption kinetics having a first hydrogen release point which occurs at normal atmospheres and at a temperature between 50.degree. C. and 90.degree. C.

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

International Nuclear Information System (INIS)

Veronesi, Francesca; Giavaresi, Gianluca; Fini, Milena; Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d'Abusco, Anna; Superti, Fabiana; Panzini, Gianluca; Misiano, Carlo; Palattella, Alberto; Selleri, Paolo; Di Girolamo, Nicola; Garbarino, Viola; Politi, Laura; Scandurra, Roberto

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm 2 /μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C gr , TiC and TiO x . • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

Titanium for salt water service

International Nuclear Information System (INIS)

Gadiyar, H.S.; Shibad, P.R.

1980-01-01

Titanium has potential as major material of construction in desalination plants, in condensers and heat exchangers, in view of its excellent corrosion resistance to salt water upto at least 120deg C. The advantages of titanium in such applications are brought out. The various specific problems such as pitting, crevice and galvanic corrosion and the preventive methods, for adopting titanium have been discussed. The hydriding problem can be overcome by suitably controlling the operating parameters such as temperature and surface preparation. A case has been made to prove the economic viability of titanium in comparison to Al-brass and Cu-Ni alloy. The future of titanium seems to be very promising in view of the negligible tube failures and outages. (auth.)

Effects of type I collagen coating on titanium osseointegration: histomorphometric, cellular and molecular analyses

International Nuclear Information System (INIS)

Sverzut, Alexander Tadeu; Crippa, Grasiele Edilaine; Tambasco de Oliveira, Paulo; Beloti, Marcio Mateus; Rosa, Adalberto Luiz; Morra, Marco

2012-01-01

The investigation of titanium (Ti) surface modifications aiming to increase implant osseointegration is one of the most active research areas in dental implantology. This study was carried out to evaluate the benefits of coating Ti with type I collagen on the osseointegration of dental implants. Acid etched Ti implants (AETi), either untreated or coated with type I collagen (ColTi), were placed in dog mandibles for three and eight weeks for histomorphometric, cellular and molecular evaluations of bone tissue response. While the histological aspects were essentially the same with both implants being surrounded by lamellar bone trabeculae, histomorphometric analysis showed more abundant bone formation in ColTi, mainly at three weeks. Cellular evaluation showed that cells harvested from bone fragments in close contact with ColTi display lower proliferative capacity and higher alkaline phosphatase activity, phenotypic features associated with more differentiated osteoblasts. Confirming these findings, molecular analyses showed that ColTi implants up-regulates the expression of a panel of genes well known as osteoblast markers. Our results present a set of evidences that coating AETi with collagen fastens the osseointegration by stimulating bone formation at the cellular and molecular levels, making this combination of morphological and biochemical modification a promising approach to treat Ti surfaces. (paper)

[The surface roughness analysis of the titanium casting founding by a new titanium casting investment material].

Science.gov (United States)

Liang, Qin-ye; Wu, Xia-yi; Lin, Xue-feng

2012-04-01

To investigate the surface roughness property of the titanium castings cast in a new investment for titanium casting. Six wax patterns (20 mm × 20 mm × 0.5 mm) were invested using two investments: three in a new titanium investment material and three in the control material (Rematitan Plus). Six titanium specimens were obtained by conventional casting. After casting, surface roughness of the specimens were evaluated with a surface profilometer. The surface roughness of the specimens cast in new titanium investment material was (1.72 ± 0.08) µm, which was much smaller than that from Rematitan Plus [(1.91 ± 0.15) µm, P cast using these two investment materials are both smooth enough to fulfill the demand of the titanium precision-casting for prosthodontic clinical use.

Electrochemical surface modification of titanium in dentistry.

Science.gov (United States)

Kim, Kyo-Han; Ramaswamy, Narayanan

2009-01-01

Titanium and its alloys have good biocompatibility with body cells and tissues and are widely used for implant applications. However, clinical procedures place more stringent and tough requirements on the titanium surface necessitating artificial surface treatments. Among the many methods of titanium surface modification, electrochemical techniques are simple and cheap. Anodic oxidation is the anodic electrochemical technique while electrophoretic and cathodic depositions are the cathodic electrochemical techniques. By anodic oxidation it is possible to obtain desired roughness, porosity and chemical composition of the oxide. Anodic oxidation at high voltages can improve the crystallinity of the oxide. The chief advantage of this technique is doping of the coating of the bath constituents and incorporation of these elements improves the properties of the oxide. Electrophoretic deposition uses hydroxyapatite (HA) powders dispersed in a suitable solvent at a particular pH. Under these operating conditions these particles acquire positive charge and coatings are obtained on the cathodic titanium by applying an external electric field. These coatings require a post-sintering treatment to improve the coating properties. Cathodic deposition is another type of electrochemical method where HA is formed in situ from an electrolyte containing calcium and phosphate ions. It is also possible to alter structure and/or chemistry of the obtained deposit. Nano-grained HA has higher surface energy and greater biological activity and therefore emphasis is being laid to produce these coatings by cathodic deposition.

Numerical assessment of bone remodeling around conventionally and early loaded titanium and titanium-zirconium alloy dental implants.

Science.gov (United States)

Akça, Kıvanç; Eser, Atılım; Çavuşoğlu, Yeliz; Sağırkaya, Elçin; Çehreli, Murat Cavit

2015-05-01

The aim of this study was to investigate conventionally and early loaded titanium and titanium-zirconium alloy implants by three-dimensional finite element stress analysis. Three-dimensional model of a dental implant was created and a thread area was established as a region of interest in trabecular bone to study a localized part of the global model with a refined mesh. The peri-implant tissues around conventionally loaded (model 1) and early loaded (model 2) implants were implemented and were used to explore principal stresses, displacement values, and equivalent strains in the peri-implant region of titanium and titanium-zirconium implants under static load of 300 N with or without 30° inclination applied on top of the abutment surface. Under axial loading, principal stresses in both models were comparable for both implants and models. Under oblique loading, principal stresses around titanium-zirconium implants were slightly higher in both models. Comparable stress magnitudes were observed in both models. The displacement values and equivalent strain amplitudes around both implants and models were similar. Peri-implant bone around titanium and titanium-zirconium implants experiences similar stress magnitudes coupled with intraosseous implant displacement values under conventional loading and early loading simulations. Titanium-zirconium implants have biomechanical outcome comparable to conventional titanium implants under conventional loading and early loading.

Hydrogen storage via polyhydride complexes

Energy Technology Data Exchange (ETDEWEB)

Jensen, C.M.; Zidan, R.A. [Univ. of Hawaii, Honolulu, HI (United States)

1998-08-01

The reversible dehydrogenation of NaAlH{sub 4} is catalyzed in toluene slurries of the NaAlH{sub 4} containing the pincer complex, IrH{sub 4} {l_brace}C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}{r_brace}. The rates of the pincer complex catalyzed dehydrogenation are about five times greater those previously found for NaAlH{sub 4} that was doped with titanium through a wet chemistry method. Homogenization of NaAlH{sub 4} with 2 mole % Ti(OBu{sup n}){sub 4} under an atmosphere of argon produces a novel titanium containing material. TPD measurements show that the dehydrogenation of this material occurs about 30 C lower than that previously found for wet titanium doped NaAlH{sub 4}. In further contrast to wet doped NaAlH{sub 4}, the dehydrogenation kinetics and hydrogen capacity of the novel material are undiminished over several dehydriding/hydriding cycles. Rehydrogenation of the titanium doped material occurs readily at 170 C under 150 atm of hydrogen. TPD measurements show that about 80% of the original hydrogen content (4.2 wt%) can be restored under these conditions.

The Half-Half Plot

NARCIS (Netherlands)

Einmahl, J.H.J.; Gantner, M.

2009-01-01

The Half-Half (HH) plot is a new graphical method to investigate qualitatively the shape of a regression curve. The empirical HH-plot counts observations in the lower and upper quarter of a strip that moves horizontally over the scatter plot. The plot displays jumps clearly and reveals further

The half-half plot

NARCIS (Netherlands)

Einmahl, J.H.J.; Gantner, M.

2012-01-01

The Half-Half (HH) plot is a new graphical method to investigate qualitatively the shape of a regression curve. The empirical HH-plot counts observations in the lower and upper quarter of a strip that moves horizontally over the scatterplot. The plot displays jumps clearly and reveals further

Anodic growth of titanium dioxide nanostructures

DEFF Research Database (Denmark)

2010-01-01

Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

New homo- and heteroleptic derivatives of trivalent ytterbium containing anion-radical 1,4-diazadiene ligands. Synthesis, properties and crystal structure of (C9H7)2Yb[2-MeC6H4NC(Me)C(Me)NC6H4Me-2] and [PhNC(Ph)C(Ph)NPh]3Yb complexes

International Nuclear Information System (INIS)

Gudilenkov, I.D.; Fukin, G.K.; Cherkasov, A.V.; Shavyrin, A.S.; Trifonov, A.A.; Larionova, Yu.E.

2008-01-01

Reaction of ytterbium bisindenyl complex (C 9 H 7 ) 2 Yb II (THF) 2 (1) with 1,4-diazabutadiene 2-MeC 6 H 4 N=C(Me)-C(Me)=NC 6 H 4 Me-2 ( Me DAD) is accompanied by the oxidation of metal atom until trivalent state and results in the formation of paramagnetic compound of metallocenes type (C 9 H 7 ) 2 Yb III ( Me DAD -. ) (3) containing 1,4-diazabutadiene anion-radical. Structure of complex 3 is ascertained by the X-ray structure analysis. Reactions of bisindenyl (1) and bisfluorenyl (C 13 H 9 ) 2 Yb II (THF) 2 (2) derivatives of bivalent ytterbium with 1,4-diazabutadiene PhN=C(Ph)-C(Ph)=NPh ( Ph DAD) (at 1:2 molar ratio of reagents) proceed with the complete break of Yb-C bonds, oxidation of ytterbium atom until trivalent state, and result in the formation of homoligand complex ( Ph DAD -. ) 3 Yb (6) containing three anion-radical 1,4-diazadiene ligands. Complex 6 was also prepared by the exchange reaction of YbCl 3 with Ph DAD -. K + (1:3) in THF. Complex 6 is characterized by the X-ray structure analysis [ru

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

Energy Technology Data Exchange (ETDEWEB)

Veronesi, Francesca [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Giavaresi, Gianluca; Fini, Milena [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Laboratory of Biocompatibility, Innovative Technologies and Advanced Therapies, Department Rizzoli RIT, Via Di Barbiano 1/10, Bologna 40136 (Italy); Longo, Giovanni [CNR Istituto di Struttura della Materia, CNR, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Ioannidu, Caterina Alexandra; Scotto d' Abusco, Anna [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Superti, Fabiana; Panzini, Gianluca [Dept. of Technologies and Health, Istituto Superiore di Sanità, Viale Regina Elena, 299 Roma (Italy); Misiano, Carlo [Romana Film Sottili, Anzio, Roma (Italy); Palattella, Alberto [Dept. of Clinical Sciences and Translational Medicine, Tor Vergata University, Via Montpellier 1, 00133 Roma (Italy); Selleri, Paolo; Di Girolamo, Nicola [Exotic Animals Clinic, Via S. Giovannini 53, 00137 Roma (Italy); Garbarino, Viola [Dept. of Radiology, S.M. Goretti Hospital, Via G. Reni 2, 04100 Latina (Italy); Politi, Laura [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Scandurra, Roberto, E-mail: roberto.scandurra@uniroma1.it [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy)

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm{sup 2}/μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C{sub gr}, TiC and TiO{sub x}. • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

The vapour phase deposition of boron on titanium by the reaction between gaseous boron trichloride and titanium metal. Final report

International Nuclear Information System (INIS)

Cameron, D.J.; Shelton, R.A.J.

1965-03-01

The reaction, between boron trichloride vapour and titanium has been investigated in the temperature range 200 - 1350 deg. C. It has been found that an initial reaction leads to the formation of titanium tetrachloride and the deposition of boron on titanium, but that except for reactions between 900 and 1000 deg. C, the system is complicated by the formation of lower titanium chlorides due to secondary reactions between the titanium and titanium tetrachloride

Topotactic reduction yielding black titanium oxide nanostructures as metallic electronic conductors.

Science.gov (United States)

Tominaka, Satoshi

2012-10-01

Detailed analyses of reduced, single crystal, rutile-type TiO(2) via high-resolution transmission electron microscopy (TEM) are reported which reveal that the reduction proceeds topotactically via interstitial diffusion of Ti ions at low temperature, around 350 °C. This important finding encouraged the production of various nanostructured reduced titanium oxides from TiO(2) precursors with morphology retention, and in the process, the synthesis of black titanium oxide nanorods using TiO(2) nanorods was demonstrated. Interestingly, as opposed to the semiconductive behavior of Ti(2)O(3) synthesized at high temperature, topotactically synthesized Ti(2)O(3) exhibits metallic electrical resistance, and the value at room temperature is quite low (topotactically synthesized Ti(2)O(3). This work shows that topotactically reduced titanium oxides can have fascinating properties as well as nanostructures.

Preparation of perovskite type titanium-bearing blast furnace slag photocatalyst doped with sulphate and investigation on reduction Cr(VI) using UV-vis light

International Nuclear Information System (INIS)

Lei, X.F.; Xue, X.X.

2008-01-01

Perovskite type titanium-bearing blast furnace slag (TBBFS) and sulphate-modified titanium-bearing blast furnace slag (SO 4 2- /TBBFS) photocatalysts were prepared by the high-energy ball milling method at different calcination temperature. The photocatalysts were characterized by XRD, FTIR, UV-vis diffuse reflectance spectra and SEM measurements. The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI) under UV-vis light irradiation. For the photocatalytic reduction of Cr(VI), the photocatalytic activities of TBBFS catalysts were found to be strongly dependent of the calcination temperature and TBBFS calcined at 700 deg. C showed a higher photocatalytic activity compared to other TBBFS catalysts. In contrast, sulphation of TBBFS improved the photocatalytic activities of SO 4 2- /TBBFS catalysts. At low calcination temperature, the photocatalytic activities of SO 4 2- /TBBFS catalysts were markedly higher than TBBFS prepared under high calcination temperature, suggesting that the presence of surface SO 4 2- favored the photocatalytic reduction of Cr(VI)

Linear Dimerization of Terminal Alkynes by Bis( tetramethylphenylcyclopentadienyl) Titanium-Magnesium Hydride and Acetylide Complexes

Czech Academy of Sciences Publication Activity Database

Mach, Karel; Gyepes, R.; Horáček, Michal; Petrusová, Lidmila; Kubišta, Jiří

2003-01-01

Roč. 68, č. 10 (2003), s. 1877-1896 ISSN 0010-0765 R&D Projects: GA ČR GA203/02/0774; GA ČR GA203/02/0436 Institutional research plan: CEZ:AV0Z4040901 Keywords : titanium * alkynes * hydrides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.041, year: 2003

A Prospective Case-Control Clinical Study of Titanium-Zirconium Alloy Implants with a Hydrophilic Surface in Patients with Type 2 Diabetes Mellitus.

Science.gov (United States)

Cabrera-Domínguez, José; Castellanos-Cosano, Lizett; Torres-Lagares, Daniel; Machuca-Portillo, Guillermo

To evaluate prospectively the behavior of narrow-diameter (3.3-mm) titanium-zirconium alloy implants with a hydrophilic surface (Straumann Roxolid SLActive) in patients with type 2 diabetes mellitus in single-unit restorations, compared with a healthy control group (assessed using the glycosylated hemoglobin HbA1c test). The patients evaluated in this study required single-unit implant treatment; 15 patients had type 2 diabetes mellitus, and 14 patients were healthy (control group [CG]). Marginal bone level (MBL) change around the implants was evaluated using conventional, sequential periapical digital radiographs. Patient HbA1c was assessed in each check-up. Normality test (Kolmogorov-Smirnov), univariate and multivariate logistic regression, analysis of variance (ANOVA), and Mann-Whitney U test were used for statistical analysis. No differences in MBL change and implant survival and success rates were found between the diabetes mellitus group (DMG) versus the control group, either during the initial recording (DMG, 0.99 ± 0.56 vs CG, 0.68 ± 0.54; P > .05) or 6 months after restoration (DMG, 1.28 ± 0.38 vs CG, 1.11 ± 0.59; P > .05). No significant correlation between HbA1c levels and MBL change was detected in these patients (P > .05). Patients with glycemic control exhibit similar outcomes to healthy individuals with regard to the investigated parameters. In light of these findings, the titanium-zirconium alloy small-diameter implants can be used in the anterior region of the mouth in type 2 diabetic patients.

Topology and Oligomerization of Mono- and Oligomeric Proteins Regulate Their Half-Lives in the Cell.

Science.gov (United States)

Mallik, Saurav; Kundu, Sudip

2018-06-05

To find additional structural constraints (besides disordered segments) that regulate protein half-life in the cell, we herein assess the influence of native topology of monomeric and sequestration of oligomeric proteins into multimeric complexes in yeast, human, and mouse. Native topology acts as a molecular marker of globular protein's mechanical resistance and consequently captures their half-life variations on genome scale. Sequestration into multimeric complexes elongates oligomeric protein half-life in the cell, presumably by burying ubiquitinoylation sites and disordered segments required for proteasomal recognition. The latter effect is stronger for proteins associated with multiple complexes and for those binding early during complex self-assembly, including proteins that oligomerize with large proportions of surface buried. After gene duplication, diversification of topology and sequestration into non-identical sets of complexes alter half-lives of paralogous proteins during the course of evolution. Thus, native topology and sequestration into multimeric complexes reflect designing principles of proteins to regulate their half-lives. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

Directory of Open Access Journals (Sweden)

Zhu W

2015-12-01

Full Text Available Wei Zhu,1 George Teel,1 Christopher M O’Brien,1 Taisen Zhuang,1 Michael Keidar,1 Lijie Grace Zhang1–3 1Department of Mechanical and Aerospace Engineering, 2Department of Biomedical Engineering, 3Department of Medicine, The George Washington University, Washington, DC, USA Abstract: Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing biomimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications

Effectiveness of transfixation and length of instrumentation on titanium and stainless steel transpedicular spine implants.

Science.gov (United States)

Korovessis, P; Baikousis, A; Deligianni, D; Mysirlis, Y; Soucacos, P

2001-04-01

This study compares the effectiveness of transfixation on the stiffness of two pedicle screw-rod constructs of different manufacture, implant design, and alloy, applied in one-and two-level instability. Four screws composed of either stainless steel or Titanium were assembled in pairs to two polymethylmethacrylate blocks to resemble one-and two-level corpectomy models and the construct underwent nondestructive torsional, extension, and flexion loading. In every loading test, each construct was tested using stainless steel or titanium rods of 4.9-mm diameter in two different lengths (short, 10 cm; long, 15 cm), not augmented or augmented with different transfixation devices or a pair of devices. The authors compared the stiffness of stainless steel and titanium constructs without cross-link with the stiffness of that reinforced with single or double Texas Scottish Rite Hospital (TSRH) cross-link, closed new-type cross-link (closed NTC), or open new-type cross-link (open NTC). The results showed that augmentation or no augmentation of short rods conferred significantly more stiffness than that of long rods of the same material in all three loading modes. The closed NTC provided the greatest increase of torsional, extension, and flexion stiffness, and single TSRH provided the least amount of stiffness. Torsional stiffness of short stainless steel rods augmented or not augmented was significantly greater than that of their titanium counterparts. Torsional stiffness of long titanium rods was always greater than that of their stainless steel counterparts. Extension stiffness of short nonaugmented titanium rods was superior to that of long titanium rods, whereas extension stiffness of nonaugmented short and long stainless steel rods was similar. Nonaugmented short titanium rods showed greater flexion stiffness than that of long titanium rods. Long stainless steel rods displayed significantly greater flexion stiffness than did their titanium counterparts. This

Studies on the Castability of Pure Titanium (Part 3) Influence of casting pressure and sprue diameter on the titanium castability

OpenAIRE

YONEDA, TAKANORI; KUROIWA, AKIHIRO; IGARASHI, YOSHIMASA; OHNO, TAKAFUMI; SEKIGUCHI, YUUJI; INOUE, YOSHIHISA; MIGO, SHINYA

1998-01-01

We analyzed the external defects of castings with mesh grid patterns with 3 different kinds of phosphate bonded casting molds with 2 parameters (sprue diameter and casting pressure). Castability with pure titanium was affected by the parameters of sprue diameter, and casting pressure with different casting molds. The sprue condition was the most affective casting condition in the all directional pressure type casting machine. In 2 types of casting molds, one was strongly affected by the casti...

Titanium minerals of placer deposits as a source for new materials

Science.gov (United States)

Kotova, Olga; Ponaryadov, Alexey

2015-04-01

Heavy mineral deposits are a source of the economic important element titanium, which is contained in ilmenite and leucoxene. The mineral composition of placer titanium ore and localization pattern of ore minerals determine their processing and enriching technologies. New data on the mineralogy of titanium ores from modern coastal-marine placer in Stradbroke Island, Eastern Australia, and Pizhma paleoplacer in Middle Timan, Russia, and materials on their basis are presented. The samples were studied by the following methods: optical-mineralogical (stereomicroscope MBS-10, polarizing microscope POLAM L-311), semiquantitative x-ray phase analysis (x-ray difractometer X'Pert PRO MPD). Besides microprobe (VEGA 3 TESCAN) and x-ray fluorescent analysis (XRF-1800 Shimadzu) were used. By the mineralogical composition ores of the both deposits are complex: enriched by valuable minerals. Apart from main ore concentrates it is possible to obtain accompanying nonmetallic products. This will increase the efficiency of deposit exploitation. Ilmenite dominates in ore sands of Stradbroke Island, and leucoxene dominates in the ores of the Pizhma titanium deposit. Australian ilmenite and its altered varieties are mainly characterized by a very high MnO content (from 5.24 to 11.08 %). The irregular distribution of iron oxides, titanium and manganese in the altered ilmenite was shown in the paper. E.g., in the areas of substitution of ilmenite by pseudorutile the concentrations of the given elements are greatly various due to various ratios of basic components in each grain. Their ratios are equal in the area of rutile evolution. Moreover, the high content of gold, diamonds and also rare earth elements (REE) and rare metals (their forms are not determined) were studied. We found native copper on the surface of minerals composing titanium-bearing sandstones of the Pizhma placer. According to the technological features of rocks (density and magnetic) studied placers are close. The

Thermodynamic analysis of salt corrosion of titanium alloys

International Nuclear Information System (INIS)

Travkin, V.V.; Pshirkov, V.F.; Kolachev, B.A.

1979-01-01

About 200 possible chemical reactions of metals, salts and oxides (in a solid state) with water (in a vapour state), and with gases (O 2 , Cl 2 , HCl) were studied by the thermodynamic analysis to elucidate a chemical nature of processes taking place at salt corrosion of titanium alloys (VT22, VT6 and VT16). Temperature dependences of isobaric-isothermic potential were considered to reveal a possibility of spontaneous course and direction of reactions as well as to obtain a comparative estimate of the probability of their pro-cedure. Thermodynamically possible schemes of the chemism of titanium alloy salt corrosion are proposed. Complex che-mical reactions take place in the presence of salt, moisture and oxygen of air on the surface of the alloys. The reactions proceed with the formation of titanium and alloying component chlorides, free chlorine and hydrogen. The free chlorine or HCl are released during pyrohydrolysis and oxidation of chlo-rides. The former ones interact with the alloy with the formation of salts, and hydrogen may be absorbed by the metal and cause embrittlement. Chlorides on the metal surface accelerate the chlorination process. NaCl acts as a cata-lyst. The determination of salt corrosion products has confirmed the process mechanism proposed

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

Science.gov (United States)

Holcombe, C.E.; Dykes, N.L.

1992-04-28

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness. No Drawings

Influence of sodium evnironment on the uniaxial tensile behavior of titanium modified type 316 stainless steel

International Nuclear Information System (INIS)

Natesan, K.; Chopra, O.K.; Kassner, T.F.

1978-01-01

True stress-true strain tensile data have been obtained for titanium modified type 316 stainless steel in the solution annealed condition and after exposure to a flowing sodium environment at temperature of 700, 650, 600 and 550 0 C. The specimens were exposed to sodium for times between 120 and 5012 h to produce carbon penetration depths in the range 0.05-0.30 mm. The Voce equation was used to describe tensile flow curves for plastic strains above 0.005. The results showed that, when compared with solution annealed specimens, the tensile flow behavior of the sodium exposed specimens is characterized by a higher strain hardening rate, which decreases rapidly as the flow stress increases. The loss in tensile ductility of the material due to carburization in sodium environment was found to be minimal. (Auth.)

Clean forming of stainless steel and titanium products by lubricious oxides

DEFF Research Database (Denmark)

Heikkilä, Irma; Wadman, Boel; Thoors, Håkan

2012-01-01

to industrial forming processes. Preliminary evaluations show a beneficial influence of two oxides types, on stainless steel and on titanium. More work is needed to test the lubricating effect in other forming operations and to analyse the sustainability aspects for products manufactured with this alternative......Big social benefits can be attained through increased use of stainless steel or titanium in new sheet metal applications. Unfortunately, forming of these materials is often a challenging and costly operation, that can lead to environmental and health problems when solving the technical limitations...

The machinability of cast titanium and Ti-6Al-4V.

Science.gov (United States)

Ohkubo, C; Watanabe, I; Ford, J P; Nakajima, H; Hosoi, T; Okabe, T

2000-02-01

This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti-6Al-4V alloy. Both CP Ti and Ti-6Al-4V were cast into magnesia molds. Two types of specimens (with alpha-case and without alpha-case) were made for CP Ti and Ti-6Al-4V. Machinability (n = 5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15000 or 30000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co-Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with alpha-case and without alpha-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.

40 CFR 180.1195 - Titanium dioxide.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

Advances in cost effective processing of titanium

International Nuclear Information System (INIS)

Nelson, O.E.

1993-01-01

Recently an industry expert pointed out that one of the greatest hindrances to the growth of titanium usage has been the low percentage of material usable in the final product. Due to the extensive processing, forming, and machining operations typically performed on titanium, yield losses are high. This is especially true in aerospace applications where most titanium is used. In engine components, the start to finish ratio, known as the buy to fly ratio, is often as high as 7 to 1. This can be illustrated by looking at the use of titanium in Pratt and Whitney engines. In the JT-8D-217 used on Boeing's 737-200, the titanium buyweight is 5,385 pounds, whereas the finished titanium, flyweight is just 758 pounds. This start to finish ratio is 7.1:1, giving titanium 17.0% of total engine weight. (orig.)

A Heterobimetallic Complex With an Unsupported Uranium(III)-Aluminum(I) Bond: (CpSiMe3)3U-AlCp* (Cp* = C5Me5)

Energy Technology Data Exchange (ETDEWEB)

Minasian, Stefan; Krinsky Ph.D., Jamin; Williams, Valerie; Arnold Ph.D., John

2008-07-23

The discovery of molecular metal-metal bonds has been of fundamental importance to the understanding of chemical bonding. For the actinides, examples of unsupported metal-metal bonds are relatively uncommon, consisting of Cp{sub 3}U-SnPh{sub 3}, and several actinide-transition metal complexes. Traditionally, bonding in the f-elements has been described as electrostatic; however, elucidating the degree of covalency is a subject of recent research. In carbon monoxide complexes of the trivalent uranium metallocenes, decreased {nu}{sub CO} values relative to free CO suggest that the U(III) atom acts as a {pi}-donor. Ephritikhine and coworkers have demonstrated that {pi}-accepting ligands can differentiate trivalent lanthanide and actinide ions, an effect that renders this chemistry of interest in the context of nuclear waste separation technology.

Electron beam melting of sponge titanium

International Nuclear Information System (INIS)

Kanayama, Hiroshi; Kusamichi, Tatsuhiko; Muraoka, Tetsuhiro; Onouye, Toshio; Nishimura, Takashi

1991-01-01

Fundamental investigations were done on electron beam (EB) melting of sponge titanium by using 80 kW EB melting furnace. Results obtained are as follows: (1) To increase the melting yield of titanium in EB melting of sponge titanium, it is important to recover splashed metal by installation of water-cooled copper wall around the hearth and to decrease evaporation loss of titanium by keeping the surface temperature of molten metal just above the melting temperature of titanium without local heating. (2) Specific power consumption of drip melting of pressed sponge titanium bar and hearth melting of sponge titanium are approximately 0.9 kWh/kg-Ti and 0.5-0.7 kWh/kg-Ti, respectively. (3) Ratios of the heat conducted to water-cooled mould in the drip melting and to water-cooled hearth in the hearth melting to the electron beam input power are 50-65% and 60-65%, respectively. (4) Surface defects of EB-melted ingots include rap which occurs when the EB output is excessively great, and transverse cracks when the EB output is excessively small. To prevent surface defects, the up-down withdrawal method is effective. (author)

Precipitated nanosized titanium dioxide for electrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Kirillov, S.A. [Joint Department of Electrochemical Energy Systems, 38A Vernadsky Ave., 03142 Kyiv (Ukraine); Institute for Sorption and Problems of Endoecology, 13 Gen. Naumov St., 03164 Kyiv (Ukraine); Lisnycha, T.V. [Institute for Sorption and Problems of Endoecology, 13 Gen. Naumov St., 03164 Kyiv (Ukraine); Chernukhin, S.I. [Joint Department of Electrochemical Energy Systems, 38A Vernadsky Ave., 03142 Kyiv (Ukraine)

2011-02-15

Two types of titanium dioxide samples precipitated from aqueous solutions of titanium tetrachloride are investigated. Crystalline materials are obtained by means of neutralization of TiCl{sub 4} with the solution of an alkali metal hydroxide. The change of the order of mixing leads to amorphous materials. The evolution of the samples upon the thermal treatment is characterized using XRD, SEM, TEM and porosity studies. The application of crystalline TiO{sub 2} as an electrode material in lithium-ion 2016 sample cells enable one to yield specific currents up to 3350 mA g{sup -1}. On the other hand, the thermal treatment of initially amorphous materials does not lead to complete crystallization, and the presence of amorphous TiO{sub 2} is well seen as the so-called capacity behavior of cyclic voltammetry curves. (author)

The "shadow sign": a radiographic differentiation of stainless steel versus titanium spinal instrumentation in spine surgery.

Science.gov (United States)

Jones-Quaidoo, Sean M; Novicoff, Wendy; Park, Andrew; Arlet, Vincent

2011-12-01

Stainless steel spinal instrumentation has been supplanted in recent years by titanium instrumentation. Knowing whether stainless steel or titanium was used in a previous surgery can guide clinical decision making processes, but frequently the clinician has no way to know what type of metal was used. We describe the radiographic "shadow sign," in which superimposed titanium rods and screws remain radiolucent enough that the contour of the underlying components can be seen on a lateral radiograph, whereas superimposed stainless steel rods and screws are completely radiopaque. This technique was evaluated using a retrospective, randomized, and blinded radiographic comparison of titanium and stainless steel spinal instrumentation. The objective was to determine whether the "shadow sign" can reliably differentiate titanium from stainless steel spinal instrumentation. Lateral radiographs from 16 cases of posterior spinal instrumentation (6 titanium, 6 stainless steel, and 2 replicates of each to assess intraobserver reliability) were randomly selected from a database of cases performed for pediatric scoliosis in a university setting from 2005 to 2009. The cases were randomized then shown to 19 orthopaedic surgery residents, 1 spine fellow, and 2 spine attendings. After the "shadow sign" was described, the surgeons were asked to determine what type of metal each implant was made of. The κ value for both stainless steel and titanium versus the gold standard was 0.83 [standard error (SE) = 0.053], indicating excellent agreement. The κ value for agreement between raters was 0.71 (SE = 0.016) and the κ value for agreement within raters was 0.70 (SE = 0.016), both of which indicated substantial agreement. The "shadow sign" can help a clinician differentiate titanium from stainless steel spinal instrumentation based on radiographic appearance alone. Furthermore, our study reveals that the level of experience in diagnosing spinal lateral radiographs also enhances the use of

Production of titanium tetrachloride

International Nuclear Information System (INIS)

Perillo, P.M.; Botbol, O.

1990-01-01

This report presents a summary of results from theoperation of a laboratory scale for the production in batches of approximately 100 gs of titanium tetrachloride by chlorination with chloroform and carbon tetrachloride between 340 deg C and 540 deg C. Chlorination agent vapors were passed through a quartz column reacting with titanium oxide powder agglomerated in little spheres. Obtained titanium tetrachloride was condensed in a condenser, taken in a ballon and then purified by fractional distillation. Optimun temperature for chloroform was 400 deg C with 74 % yield and for carbon tetrachloride was 500 deg C with 69 % yield. (Author) [es

Studies on the promotion of nickel—alumina coprecipitated catalysts: I. Titanium oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Mercera, P.D.L.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

A series of TiO2-promoted nickel—alumina catalysts has been prepared and characterized. The promoter was added in various proportions to a calcined coprecipitated nickel—alumina material by adsorption of the acetylacetonate complex of titanium, followed by further calcination and reduction. The

Synthesis, structure, spectroscopy and redox energetics of a series of uranium(4) mixed-ligand metallocene complexes

Energy Technology Data Exchange (ETDEWEB)

Thomson, R.K.; Scott, B.L.; Morris, D.E.; Kiplinger, J.L. [Los Alamos National Laboratory, Los Alamos, NM (United States)

2010-06-15

A series of uranium(IV) mixed-ligand amide-halide/pseudo-halide complexes (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](X) (X = F (1), Cl (2), Br (3), I (4), N{sub 3} (5), NCO (6)), (C{sub 5}Me{sub 5}){sub 2}U(NPh{sub 2})(X) (X = Cl (7), N{sub 3} (8)), and (C{sub 5}Me{sub 5}){sub 2}U[N(Ph)(SiMe{sub 3})](X) (X Cl (9), N{sub 3} (10)) have been prepared by one electron oxidation of the corresponding uranium(III) amide precursors using either copper halides, silver iso-cyanate, or triphenylphosphine gold(I)azide. Agostic U---H-C interactions and {eta}{sub 3}-(N,C,C') coordination are observed for these complexes in both the solid-state and solution. There is a linear correlation between the chemical shift values of the C{sub 5}Me{sub 5} ligand protons in the {sup 1}H NMR spectra and the U(IV)/U(III) reduction potentials of the (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](X) complexes, suggesting that there is a common origin, that is overall {sigma}-/{pi}-donation from the ancillary (X) ligand to the metal, contributing to both observables. Optical spectroscopy of the series of complexes 1-6 is dominated by the (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}] core, with small variations derived from the identity of the halide/pseudo-halide. The considerable {pi}-donating ability of the fluoride ligand is reflected in both the electrochemistry and UV-visible-NIR spectroscopic behavior of the fluoride complex (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](F) (1). The syntheses of the new trivalent uranium amide complex, (C{sub 5}Me{sub 5}){sub 2}U[N(Ph)(SiMe{sub 3})](THF), and the two new weakly-coordinating electrolytes, [Pr{sub 4}N][B{l_brace}3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3{r_brace}4}] and [Pr{sub 4}N][B(C{sub 6}F{sub 5}){sub 4}], are also reported. (authors)

21 CFR 73.2575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the requirements...

Complete titanium substitution by boron in a tetragonal prism: exploring the complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 theory.

Science.gov (United States)

Fokwa, Boniface P T; Hermus, Martin

2011-04-18

Polycrystalline samples and single crystals of four members of the new complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 X-ray diffraction as well as energy- and wavelength-dispersive X-ray spectroscopy analyses. They crystallize with the tetragonal Ti(3)Co(5)B(2) structure type in space group P4/mbm (No. 127). Tetragonal prisms of Ru/Ir atoms are filled with titanium in the boron-poorest phase (Ti(3)Ru(2.9)Ir(2.1)B(2)). Gradual substitution of titanium by boron then results in the successive filling of this site by a Ti/B mixture en route to the complete boron occupation, leading to the boron-richest phase (Ti(2)Ru(2.8)Ir(2.2)B(3)). Furthermore, both ruthenium and iridium share two sites in these structures, but a clear Ru/Ir site preference is found. First-principles density functional theory calculations (Vienna ab initio simulation package) on appropriate structural models (using a supercell approach) have provided more evidence on the stability of the boron-richest and -poorest phases, and the calculated lattice parameters corroborate very well with the experimentally found ones. Linear muffin-tin orbital atomic sphere approximation calculations further supported these findings through crystal orbital Hamilton population bonding analyses, which also show that the Ru/Ir-B and Ru/Ir-Ti heteroatomic interactions are mainly responsible for the structural stability of these compounds. Furthermore, some stable and unstable phases of this complex series could be predicted using the rigid-band model. According to the density of states analyses, all phases should be metallic conductors, as was expected from these metal-rich borides.

Transition rate diagrams and excitation of titanium in a glow discharge in argon and neon

Science.gov (United States)

Weiss, Zdeněk; Steers, Edward B. M.; Pickering, Juliet C.

2018-06-01

Emission spectra of titanium in a Grimm-type glow discharge in argon and neon were studied using the formalism of transition rate diagrams. Ti I spectra in argon and neon discharges are similar, without signs of selective excitation, and populations of Ti I levels exhibit a decreasing trend as function of energy, except for some scatter. A major excitation process of Ti II in argon discharge is charge transfer from argon ions to neutral titanium. In neon discharge, a strong selective excitation was observed of Ti II levels at ≈13.3-13.4 eV relative to the Ti I ground state. It was attributed to charge transfer from doubly charged titanium ions to neutral titanium, while the Ti++ ions are produced by charge transfer and ionization of neutral titanium by neon ions. Cascade excitation is important for Ti II levels up to an energy of ≈13 eV relative to the Ti I ground state, both in argon and neon discharges.

Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions

NARCIS (Netherlands)

Amin Yavari, S.; Loozen, L.; Paganelli, F. L.; Bakhshandeh, S.; Lietaert, K.; Groot, J. A.; Fluit, A. C.; Boel, C. H E; Alblas, J.; Vogely, H. C.; Weinans, H.; Zadpoor, A. A.

2016-01-01

Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with

In vivo evaluation of immediately loaded stainless steel and titanium orthodontic screws in a growing bone.

Directory of Open Access Journals (Sweden)

Kerstin Gritsch

Full Text Available The present work intends to evaluate the use of immediate loaded orthodontic screws in a growing model, and to study the specific bone response. Thirty-two screws (half of stainless steel and half of titanium were inserted in the alveolar bone of 8 growing pigs. The devices were immediately loaded with a 100 g orthodontic force. Two loading periods were assessed: 4 and 12 weeks. Both systems of screws were clinically assessed. Histological observations and histomorphometric analysis evaluated the percent of "bone-to-implant contact" and static and dynamic bone parameters in the vicinity of the devices (test zone and in a bone area located 1.5 cm posterior to the devices (control zone. Both systems exhibit similar responses for the survival rate; 87.5% and 81.3% for stainless steel and titanium respectively (p = 0.64; 4-week period, and 62.5% and 50.0% for stainless steel and titanium respectively (p = 0.09; 12-week period. No significant differences between the devices were found regarding the percent of "bone-to-implant contact" (p = 0.1 or the static and dynamic bone parameters. However, the 5% threshold of "bone-to-implant contact" was obtained after 4 weeks with the stainless steel devices, leading to increased survival rate values. Bone in the vicinity of the miniscrew implants showed evidence of a significant increase in bone trabecular thickness when compared to bone in the control zone (p = 0.05. In our study, it is likely that increased trabecular thickness is a way for low density bone to respond to the stress induced by loading.

In vivo evaluation of immediately loaded stainless steel and titanium orthodontic screws in a growing bone.

Science.gov (United States)

Gritsch, Kerstin; Laroche, Norbert; Bonnet, Jeanne-Marie; Exbrayat, Patrick; Morgon, Laurent; Rabilloud, Muriel; Grosgogeat, Brigitte

2013-01-01

The present work intends to evaluate the use of immediate loaded orthodontic screws in a growing model, and to study the specific bone response. Thirty-two screws (half of stainless steel and half of titanium) were inserted in the alveolar bone of 8 growing pigs. The devices were immediately loaded with a 100 g orthodontic force. Two loading periods were assessed: 4 and 12 weeks. Both systems of screws were clinically assessed. Histological observations and histomorphometric analysis evaluated the percent of "bone-to-implant contact" and static and dynamic bone parameters in the vicinity of the devices (test zone) and in a bone area located 1.5 cm posterior to the devices (control zone). Both systems exhibit similar responses for the survival rate; 87.5% and 81.3% for stainless steel and titanium respectively (p = 0.64; 4-week period), and 62.5% and 50.0% for stainless steel and titanium respectively (p = 0.09; 12-week period). No significant differences between the devices were found regarding the percent of "bone-to-implant contact" (p = 0.1) or the static and dynamic bone parameters. However, the 5% threshold of "bone-to-implant contact" was obtained after 4 weeks with the stainless steel devices, leading to increased survival rate values. Bone in the vicinity of the miniscrew implants showed evidence of a significant increase in bone trabecular thickness when compared to bone in the control zone (p = 0.05). In our study, it is likely that increased trabecular thickness is a way for low density bone to respond to the stress induced by loading.

Titanium oxide nanocoating on a titanium thin film deposited on a glass substrate

Energy Technology Data Exchange (ETDEWEB)

Kotsedi, L., E-mail: kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Cummings, F.R. [University of the Western Cape, Electron Microscopy Unit, Physics Department, Bellville 7535, Cape Town (South Africa); Turco, S. Lo; Ntwaeaborwa, O.M. [Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Milano, Italy Via Giovanni Pascoli, 70/3, 20133 Milano (Italy); Ramponi, R. [Institute for Photonics and Nanotechnologies (IFN)-CNR, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa)

2016-03-31

Thin films of titanium were deposited on a glass substrate using electron beam evaporator. Femtosecond laser pulses were focused on the surface of the films, and the samples were scanned while mounted on the motorized computer-controlled motion stage to produce an areal modification of the films. X-ray diffraction of the laser-patterned samples showed evidence of the formation of a γ-Ti{sub 3}O{sub 5} with a monoclinic phase. Rutherford backscattering spectrometry simulation showed that there is an increase in the oxygen concentration as the average laser fluence is increased. Time of flight secondary ions mass spectrometry analysis showed an even distribution of the titanium and oxygen ions on the sample and also ionized molecules of the oxides of titanium were observed. The formation of the oxide of titanium was further supported using the UV–Vis-NIR spectroscopy, which showed that for 0.1 J/cm{sup 2} fluence, the laser-exposed film showed the electron transfer band and the d–d transition peak of titanium was observed at lower wavelengths. - Highlights: • γ-Ti{sub 3}O{sub 5} formed using femtosecond laser. • Fluence and oxygen relation were studied. • Nanoflakes of γ-Ti{sub 3}O{sub 5} were observed under HRSEM.

21 CFR 73.1575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements...

Interpretation of stream programs: characterizing type 2 polynomial time complexity

OpenAIRE

Férée , Hugo; Hainry , Emmanuel; Hoyrup , Mathieu; Péchoux , Romain

2010-01-01

International audience; We study polynomial time complexity of type 2 functionals. For that purpose, we introduce a first order functional stream language. We give criteria, named well-founded, on such programs relying on second order interpretation that characterize two variants of type 2 polynomial complexity including the Basic Feasible Functions (BFF). These charac- terizations provide a new insight on the complexity of stream programs. Finally, we adapt these results to functions over th...

Adhesive-Bonded Tab Attaches Thermocouples to Titanium

Science.gov (United States)

Cook, C. F.

1982-01-01

Mechanical strength of titanium-alloy structures that support thermocouples is preserved by first spotwelding thermocouples to titanium tabs and then attaching tabs to titanium with a thermosetting adhesive. In contrast to spot welding, a technique previously used for thermocouples, fatigue strength of the titanium is unaffected by adhesive bonding. Technique is also gentler than soldering or attaching thermocouples with a tap screw.

Platelet half-life in patients with primary hyperlipoproteinemia type IIa, IIb, and IV according to Fredrickson with and without clinical signs of atherosclerosis

Energy Technology Data Exchange (ETDEWEB)

Jaeger, E; Sinzinger, H; Widhalm, K; Kaliman, J; Hoefer, R [Vienna Univ. (Austria). 2. Medizinische Klinik; Ludwig Boltzmann-Institut fuer Nuklearmedizin, Vienna (Austria); Vienna Univ. (Austria). Kinderklinik; Vienna Univ. (Austria). Kardiologische Klinik)

1982-09-01

It is generally accepted that platelet half-life is shortened in atherosclerotic vascular diseases. Concerning changes due to hyperlipoproteinemia (HLP), however, there exist only few data. Therefore, we examined the platelet-half life in 60 patients with recently discovered HLP type IIa, IIb and IV according to Fredrickson before treatment in comparison to 60 controls. 33 of the HLP-patients had no clinical symptoms of angiopathy. 27 patients suffered from peripheral vascular disease or from coronary heart disease as verified by angiography. The labelling of autologous platelets was performed with 100..mu..Ci of /sup 111/Indium-oxine-sulfate at 37/sup 0/C for 5 minutes. The mean labelling efficiency was 90%, the recovery after 2 hours about 70%. Serum lipoproteins were estimated by means of ultracentrifugation and polyanionprecipitation according to Lipid Research Clinic Methods. In the patients with HLP platelet half-life was significantly shortened in comparison to the control group (p < 0.01). These changes were most pronounced in patients with HLP-type IIa and with atherosclerotic lesions, respectively. In patients with HLP-type IIa a very close correlation could be demonstrated between platelet half-life and LDL-cholesterol (r = -0.72; p < 0.001) as well as total cholesterol (r = -0.73; p < 0.001). These data prove that in HLP in-vivo platelet function as measured by platelet survival is significantly influenced even before the occurrence of clinically relevant symptoms of atherosclerosis.

Criterion of titanium aviation alloy application

International Nuclear Information System (INIS)

Stasyunas, O.P.

1976-01-01

The most significant statistic mechanical characteristics are presented of titanium as compared with those of aluminium and steel. Based on these data one can draw conclusions as to the advantages and disadvantages of titanium. High chemical activity and diffusivity of titanium place limitations on the use of its alloys. Despite the promising features of a needle-like structure, specifications still keep relying on a globular structure, which is explained by the easeiness of the production. Titanium is expensive, sometimes its cost may by a factor of 20 exceed that of other aviation materials

21 CFR 73.575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared TiO2, free from admixture with other substances. (2) Color...

21 CFR 73.3126 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

The effect of titanium implant surface modification on the dynamic process of initial microbial adhesion and biofilm formation

NARCIS (Netherlands)

Han, A.; Li, X.; Huang, B.; Tsoi, J.K.-H.; Matinlinna, J.P.; Chen, Z.; Deng, D.M.

2016-01-01

Purpose: The aim of the study was to investigate the dynamic process of biofilm adhesion on titanium implant with two surface treatments, either pickled (PT) or moderately roughened by sandblasting with large grits and acid-etched (SLA). Materials and methods: Two types of titanium disks with

A comparison of torque expression between stainless steel, titanium molybdenum alloy, and copper nickel titanium wires in metallic self-ligating brackets.

Science.gov (United States)

Archambault, Amy; Major, Thomas W; Carey, Jason P; Heo, Giseon; Badawi, Hisham; Major, Paul W

2010-09-01

The force moment providing rotation of the tooth around the x-axis (buccal-lingual) is referred to as torque expression in orthodontic literature. Many factors affect torque expression, including the wire material characteristics. This investigation aims to provide an experimental study into and comparison of the torque expression between wire types. With a worm-gear-driven torquing apparatus, wire was torqued while a bracket mounted on a six-axis load cell was engaged. Three 0.019 x 0.0195 inch wire (stainless steel, titanium molybdenum alloy [TMA], copper nickel titanium [CuNiTi]), and three 0.022 inch slot bracket combinations (Damon 3MX, In-Ovation-R, SPEED) were compared. At low twist angles (wires were not statistically significant. At twist angles over 24 degrees, stainless steel wire yielded 1.5 to 2 times the torque expression of TMA and 2.5 to 3 times that of nickel titanium (NiTi). At high angles of torsion (over 40 degrees) with a stiff wire material, loss of linear torque expression sometimes occurred. Stainless steel has the largest torque expression, followed by TMA and then NiTi.

Welding and Joining of Titanium Aluminides

Science.gov (United States)

Cao, Jian; Qi, Junlei; Song, Xiaoguo; Feng, Jicai

2014-01-01

Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing–microstructure–property relationships in the welding and joining of titanium aluminides to themselves and to other materials. PMID:28788113

Osteoblast response on co-modified titanium surfaces via anodization and electrospinning

Energy Technology Data Exchange (ETDEWEB)

Bayram, Cem [Nanotechnology and Nanomedicine Division, Hacettepe University, Ankara, Beytepe, 06800 (Turkey); Chemistry Department, Aksaray University, Aksaray, 68100 (Turkey); Demirbilek, Murat; Yalçın, Eda [Nanotechnology and Nanomedicine Division, Hacettepe University, Ankara, Beytepe, 06800 (Turkey); Bozkurt, Murat; Doğan, Metin [Orthopaedics and Traumatology Division, Yıldırım Beyazıt University, School of Medicine, Cankaya, 06550 (Turkey); Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr [Chemistry Department, Hacettepe University, Ankara, Beytepe, 06800 (Turkey)

2014-01-01

Topography plays a key role in osseointegration and surface modifications at the subcellular level, increasing initial cell attachment in the early period. In the past decade, nanosized texture on metal like a nanotube layer and also more recently extracellular matrix like surface modifications – such as polymeric nanofibrils – have been proposed for a better osseointegration in the literature. Here, we investigate two types of nanoscaled modifications alone and together for the first time. We characterized different types of surface modifications morphologically and investigated how they affected osteoblast cells in vitro, in terms of cell adhesion, proliferation, alkaline phosphatase activity and calcium content. We anodized titanium samples with a thickness of 0.127 mm to obtain a nanotubular titania layer and the silk fibroin (SF), as a biocompatible polymeric material, was electrospun onto both anodized and unanodized samples to acquire 4 sample groups. We analyzed the resulting samples morphologically by scanning electron microscopy (SEM). Cell adhesion, proliferation, alkaline phosphatase (ALP) activity and calcium content were evaluated at 3, 7 and 14 days. We found that cell proliferation increased by 70% on the groups having two modifications respect to unmodified titanium and after 7 days, ALP activity and calcium content were 110% and 150%, respectively, higher on surfaces having both surface treatments than that of unmodified group. In conclusion, a nanotube layer and SF nanofibers on a titanium surface enhanced cell attachment and proliferation most. Comodification of titanium surfaces by anodization and SF electrospinning may be useful to enhance osseointegration but it requires in vivo confirmation.

Cytological features of complex type fibroadenoma in comparison with non-complex type fibroadenoma.

Science.gov (United States)

Ohashi, Ryuji; Matsubara, Miyuki; Watarai, Yasuhiko; Yanagihara, Keiko; Yamashita, Koji; Tsuchiya, Shin-Ichi; Takei, Hiroyuki; Naito, Zenya

2016-09-01

To determine the cytomorphological features of complex type fibroadenoma (CFA), we reviewed fine needle aspiration (FNA) cytology with correlation to its histopathology findings, and compared them with non-complex type fibroadenoma (NCFA). From excisional biopsy or resected specimens of fibroadenoma (FA) cases treated at our institution from 2004 to 2013, we chose 46 patients who underwent FNA before a diagnosis of FA was established. We histologically re-classified them into two groups: CFA and NCFA. FNA diagnosis was retrospectively re-evaluated from FNA reports. We further re-assessed detailed characteristics of each FNA smears to identify cytomorphological features of CFA. We found that 15 cases fulfilled the diagnostic criteria of CFA, in which 7 (46.7 %) had an FNA diagnosis of "suspicious for malignancy" or "indeterminate" while only 2 NCFA cases had that of "indeterminate" (p = 0.004). FNA smears from CFA cases showed discohesiveness, enlarged nuclei, prominent nucleoli, and fewer myoepithelial cells more often than NCFA. Although no significant difference was noted in patients' age and tumor size between CFA and NCFA, 5 CFA cases (33.3 %) were accompanied by the presence of carcinoma in the same breast or the contralateral breast while no NCFA cases had carcinoma in the breast. FNA of CFA can lead to erroneous or indeterminate interpretation, due to proliferative and/or hyperplastic changes of ductal epithelium with or without atypia. It is important to recognize the disease entity and characteristic cytomorphological findings of CFA to reach accurate FNA diagnosis of breast lesions.

Skull Bone Defects Reconstruction with Custom-Made Titanium Graft shaped with Electron Beam Melting Technology: Preliminary Experience in a Series of Ten Patients.

Science.gov (United States)

Francaviglia, Natale; Maugeri, Rosario; Odierna Contino, Antonino; Meli, Francesco; Fiorenza, Vito; Costantino, Gabriele; Giammalva, Roberto Giuseppe; Iacopino, Domenico Gerardo

2017-01-01

Cranioplasty represents a challenge in neurosurgery. Its goal is not only plastic reconstruction of the skull but also to restore and preserve cranial function, to improve cerebral hemodynamics, and to provide mechanical protection of the neural structures. The ideal material for the reconstructive procedures and the surgical timing are still controversial. Many alloplastic materials are available for performing cranioplasty and among these, titanium still represents a widely proven and accepted choice. The aim of our study was to present our preliminary experience with a "custom-made" cranioplasty, using electron beam melting (EBM) technology, in a series of ten patients. EBM is a new sintering method for shaping titanium powder directly in three-dimensional (3D) implants. To the best of our knowledge this is the first report of a skull reconstruction performed by this technique. In a 1-year follow-up no postoperative complications have been observed and good clinical and esthetic outcomes were achieved. Costs higher than those for other types of titanium mesh, a longer production process, and the greater expertise needed for this technique are compensated by the achievement of most complex skull reconstructions with a shorter operative time.

Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone

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Eduardo Aloisio Fleck NEUMANN

2014-08-01

Full Text Available Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1, polyetheretherketone (PEEK screws (Group 2, and 30% carbon fiber-reinforced PEEK screws (Group 3. The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey’s range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05. Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone.

Science.gov (United States)

Neumann, Eduardo Aloisio Fleck; Villar, Cristina Cunha; França, Fabiana Mantovani Gomes

2014-01-01

Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

KAUST Repository

Gooneratne, Chinthaka Pasan

2011-11-01

Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

KAUST Repository

Gooneratne, Chinthaka Pasan; Liang, Cai; Useinov, Arthur; Kosel, Jü rgen; Giouroudi, Ioanna

2011-01-01

Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

Ion exchange of some transition metal cations on hydrated titanium dioxide in aqueous ammonia solutions

International Nuclear Information System (INIS)

Bilewicz, A.; Narbutt, J.; Dybczynski, R.

1992-01-01

The adsorption of transition metal cations on hydrated titanium dioxide in complexing ammonia and amine solutions has been studied as a function of ammonia (amine) concentration. The relationships between the distribution coefficients and ammonia concentration as well as the effects of various amines on sorption of transition metals indicate that a coordinate bond is formed between the metal ions and the hydroxy groups of the sorbent. The distribution coefficients of silver(I) and cobalt(II), which form strong ammonia complexes in aqueous solutions, decrease with increasing concentration of ammonia already at concentrations exceeding 10 -3 *mol*dm -3 . Cations of zinc, manganese and mercury which form much weaker ammonia complexes do not exhibit any effect of ammonia concentration in the whole range investigated. In the case of sorption of macroamounts of ammonia or amine complexes of silver, the molecular sieve effect plays an important role. The differences in the affinity of hydrated titanium dioxide for ammonia solvates of various transition metal ions can serve as a tool for effective separation of these ions in ammonia solutions. (author) 10 refs.; 4 figs.; 1 tab

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites.

Science.gov (United States)

Li, Feng; Jiang, Xiaosong; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao

2018-04-16

Biomaterial composites made of titanium and hydroxyapatite (HA) powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD), back scattered electron imaging (BSE), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca₃(PO₄)₂, Ti x P y , and Ti₃O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed.

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites

Directory of Open Access Journals (Sweden)

Feng Li

2018-04-01

Full Text Available Biomaterial composites made of titanium and hydroxyapatite (HA powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD, back scattered electron imaging (BSE, scanning electron microscope (SEM equipped with energy dispersive spectrometer (EDS, electron probe microanalyzer (EPMA, and transmission electron microscope (TEM. The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca3(PO42, TixPy, and Ti3O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed.

Half-maximal supersymmetry from exceptional field theory

Energy Technology Data Exchange (ETDEWEB)

Malek, Emanuel [Arnold Sommerfeld Center for Theoretical Physics, Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2017-10-15

We study D ≥ 4-dimensional half-maximal flux backgrounds using exceptional field theory. We define the relevant generalised structures and also find the integrability conditions which give warped half-maximal Minkowski{sub D} and AdS{sub D} vacua. We then show how to obtain consistent truncations of type II / 11-dimensional SUGRA which break half the supersymmetry. Such truncations can be defined on backgrounds admitting exceptional generalised SO(d - 1 - N) structures, where d = 11 - D, and N is the number of vector multiplets obtained in the lower-dimensional theory. Our procedure yields the most general embedding tensors satisfying the linear constraint of half-maximal gauged SUGRA. We use this to prove that all D ≥ 4 half-maximal warped AdS{sub D} and Minkowski{sub D} vacua of type II / 11-dimensional SUGRA admit a consistent truncation keeping only the gravitational supermultiplet. We also show to obtain heterotic double field theory from exceptional field theory and comment on the M-theory / heterotic duality. In five dimensions, we find a new SO(5, N) double field theory with a (6 + N)-dimensional extended space. Its section condition has one solution corresponding to 10-dimensional N = 1 supergravity and another yielding six-dimensional N = (2, 0) SUGRA. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Welding and Joining of Titanium Aluminides

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Jian Cao

2014-06-01

Full Text Available Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing–microstructure–property relationships in the welding and joining of titanium aluminides to themselves and to other materials.

Clinical presentations of 23 half-siblings from a mosaic neurofibromatosis type 1 sperm donor.

Science.gov (United States)

Ejerskov, C; Farholt, S; Skovby, F; Vestergaard, E M; Haagerup, A

2016-03-01

The Danish sperm donor number 7042 has fathered several offspring with neurofibromatosis type 1 (NF1) worldwide. NF1 is caused by loss-of-function mutations in the NF1 gene and more than 1000 NF1 mutations are identified. Analysis of the donor sperm demonstrated gonosomal mosaicism with an intragenic deletion involving exons 15-29 in the NF1 gene. At the two Danish reference centres for NF1 patients, we evaluated 23 half-siblings from the donor. Nine were diagnosed with NF1. The severity grade of NF1 progressed from minimal to mild/moderate within 3 years of follow-up. The NF1 phenotype shows great variability in intra- and inter-family expressivity and to date only two NF1 genotype-phenotype correlations have been established. This rare possibility of a long-term follow-up of a cohort of half-siblings with NF1 makes further studies including phenotypic variability and search for modifier genes possible. To achieve this goal, we have initiated The International Donor 7042 NF1 Offspring Registry. Research facilitated via this registry may reveal important new knowledge of clinical characteristics and prognostics for the specific NF1 genotype and thereby contribute to future individualised targeted clinical follow-up and treatment. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ultrasonic effects on titanium tanning of leather.

Science.gov (United States)

Peng, Biyu; Shi, Bi; Sun, Danhong; Chen, Yaowen; Shelly, Dennis C

2007-03-01

The effects of ultrasound on titanium tanning of leather were investigated. Either 20 or 40 kHz ultrasound was applied to the titanium tanning of pigskins. Five different treatment conditions were carried out and the effects were examined, such as leather shrinkage temperature (T(s)), titanium content and titanium distribution in the leather. Overall heat loading was carefully controlled. Results showed that 20 kHz ultrasound effectively improves titanium agent penetration into the hide and increases the leather's shrinkage temperature. Doubling the frequency to 40 kHz produced negligible enhancements. An impressive 105.6 degrees C T(s) was achieved using 20 kHz ultrasound pretreatment of the tanning liquor followed by 20 kHz ultrasound in the tanning mixture (liquor plus pigskins) in a special salt-free medium. Finally, using a unique ultrasonic tanning drum with 26.5 kHz ultrasound, the T(s) reached a record level of 106.5 degrees C, a value not achieved in conventional (no ultrasound) titanium tanning. The ultrasonic effects on titanium tanning of leather are judged to make a superior mineral tanned leather.

Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood.

Science.gov (United States)

Hewitt, Rachel E; Vis, Bradley; Pele, Laetitia C; Faria, Nuno; Powell, Jonathan J

2017-10-01

Pigment grade titanium dioxide is composed of sub-micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell-particle associations could be determined in immune cells of human whole blood at "real life" concentrations. In vitro assays, initially using isolated peripheral blood mononuclear cells, identified titanium dioxide associated with the surface of, and within, immune cells by darkfield reflectance in imaging flow cytometry. This was confirmed at the population level by side scatter measurements using conventional flow cytometry. Next, it was demonstrated that imaging flow cytometry could quantify titanium dioxide particle-bearing cells, within the immune cell populations of fresh whole blood, down to titanium dioxide levels of 10 parts per billion, which is in the range anticipated for human blood following titanium dioxide ingestion. Moreover, surface association and internal localization of titanium dioxide particles could be discriminated in the assays. Overall, results showed that in addition to the anticipated activity of blood monocytes internalizing titanium dioxide particles, neutrophil internalization and cell membrane adhesion also occurred, the latter for both phagocytic and nonphagocytic cell types. What happens in vivo and whether this contributes to activation of one or more of these different cells types in blood merits further attention. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

A new method for production of titanium vapor and synthesis of titanium nitride coatings

Science.gov (United States)

Grigoriev, Sergey N.; Melnik, Yury A.; Metel, Alexander S.; Volosova, Marina A.

2018-03-01

It is proposed to synthesize on machine parts and cutting tools wear-resistant titanium nitride coatings with the help of the hollow-cathode glow discharge, a molybdenum crucible for titanium evaporation being used as the anode of the discharge and a process vacuum chamber being used as the hollow cathode. The research revealed that at the anode surface area less than a critical value S* = (2m/M)1/2S, where S is the area of the chamber walls, m is the mass of electrons and M is the mass of ions, the anode fall of potential is positive and grows from ˜50 V at argon pressure p = 0.2 Pa to ˜2 kV at p = 0.02 Pa. At the discharge current I = 0.6 A electrons accelerated by the anode fall of 0.9 kV transport into the crucible with the inner diameter of 12 mm the power of ˜0.54 kW, which allows the titanium evaporation and the coating deposition rate of 5 µm·h-1 on a substrate distanced from the crucible at 100 mm. After the argon is replaced with the nitrogen, titanium nitride coating without titanium droplets is synthesized the deposition rate amounting to about the same value.

Appcelerator Titanium patterns and best practices

CERN Document Server

Pollentine, Boydlee

2013-01-01

The book takes a step-by-step approach to help you understand CommonJS and Titanium architecture patterns, with easy to follow samples and plenty of in-depth explanations If you're an existing Titanium developer or perhaps a new developer looking to start off your Titanium applications "the right way", then this book is for you. With easy to follow examples and a full step-by-step account of architecting a sample application using CommonJS and MVC, along with chapters on new features such as ACS, you'll be implementing enterprise grade Titanium solutions in no time. You should have some JavaSc

Synthetic approaches to lanthanide complexes with tetrapyrrole type ligands

International Nuclear Information System (INIS)

Pushkarev, V E; Tomilova, L G; Tomilov, Yu V

2008-01-01

Approaches to the synthesis of single-, double- and triple-decker complexes of lanthanides with phthalocyanines and their analogues known to date are considered. Examples of preparation of sandwich-type complexes based on other metals of the Periodic system are given.

Research and Development on Titanium Alloys

Science.gov (United States)

1949-10-31

information concerning the runs made * * In order to check the general operation of the train and furnace, a number of qualitative runs were made. These runs... General Technique. * . . * * . 109 The Analysis of Titanium . . . . ... ... 112 Notes and Comments, . . . .. . .. . . . 113 The Results from Vacuum...described in this report are as follows: 1. Arc ielting Titanium-Base Alloys. 2. Evaluation of Experimental Titanium-Base Alloys. 3. Investigation of

Titanium oxide fever

International Nuclear Information System (INIS)

De Jonge, D.; Visser, J.

2012-01-01

One measure to improve air quality is to apply photo-catalytic substances that capture NOx onto the road surface or onto baffle boards alongside the roads. The effect of titanium oxide containing clinkers with coating was discussed in the report 'Demonstration project of air-purifying pavement in Hengelo, The Netherlands' that was published in May 2011. This article examines the way in which the effectiveness of this study was determined. Can titanium oxide containing clinkers and coatings indeed capture NOx?. [nl

Acceptor Type Vacancy Complexes In As-Grown ZnO

International Nuclear Information System (INIS)

Zubiaga, A.; Tuomisto, F.; Zuniga-Perez, J.

2010-01-01

One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (∼3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, Li Zn and Na Zn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

Acceptor Type Vacancy Complexes In As-Grown ZnO

Science.gov (United States)

Zubiaga, A.; Tuomisto, F.; Zuñiga-Pérez, J.

2010-11-01

One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (˜3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, LiZn and NaZn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

Vacancy site occupation by Co and Ir in half-Heusler ZrNiSn and conversion of the thermoelectric properties from n-type to p-type

International Nuclear Information System (INIS)

Kimura, Yoshisato; Tanoguchi, Toshiyasu; Kita, Takuji

2010-01-01

The n-type thermoelectric properties of the half-Heusler compound ZrNiSn can be converted to p-type by the addition of Co and Ir. We found that Co and Ir atoms preferably occupy the vacancy sites instead of substituting at Ni sites. This implies that the phase stability of the compound gradually changes towards that of the Heusler compound Zr(Ni,M) 2 Sn, where M is Co and/or Ir. The occupation of vacancy sites by Co and Ir atoms leads to a drastic reduction in lattice thermal conductivity owing to the enhancement of phonon scattering by the solid solution effect.

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

Directory of Open Access Journals (Sweden)

Wen-Tao Yu

2016-08-01

Full Text Available The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix during hot processing as demonstrated by the determination of extracted carbides from the steel matrix. Meanwhile, titanium suppressed the precipitation of secondary carbides during annealing. The appropriate amount of titanium addition decreased the size and fraction of primary carbides in the as-cast ingot, and improved the mechanical properties of the annealed steel.

Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite

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Richard C. Petersen

2014-12-01

Full Text Available The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo

Magnetic properties and phase stability of half-metal-type Co2Cr1-xFexGa alloys

International Nuclear Information System (INIS)

Kobayashi, K.; Umetsu, R.Y.; Fujita, A.; Oikawa, K.; Kainuma, R.; Fukamichi, K.; Ishida, K.

2005-01-01

The magnetic properties and phase stability of half-metal-type Co 2 Cr 1-x Fe x Ga alloys were investigated by differential scanning calorimetry (DSC), in a superconducting quantum interference device (SQUID) magnetometer and in a vibrating sample magnetometer (VSM), and by transmission electron microscopy (TEM). It was found that the L2 1 -type single-phase is obtainable for the entire concentration of x and that the value of the saturation magnetic moment M s at 4.2K in the lower composition range of x is in agreement with the generalized Slater-Pauling line, while it is rather larger than the generalized Slater-Pauling line above x=0.6. The Curie temperature T c monotonically increases, whereas the transition temperature from the L2 1 - to B2-type phase T t B2/L2 1 is almost constant at 1082+/-13K with increasing x

Formation of titanium diboride coatings during the anodic polarization of titanium in a chloride melt with a low boron oxide content

Science.gov (United States)

Elshina, L. A.; Malkov, V. B.; Molchanova, N. G.

2015-02-01

The corrosion-electrochemical behavior of titanium in a molten eutectic mixture of cesium and sodium chlorides containing up to 1 wt % boron oxide is studied in the temperature range 810-870 K in an argon atmosphere. The potential, the current, and the rate of titanium corrosion are determined. The optimum conditions of forming a dense continuous titanium diboride coating on titanium with high adhesion to the metallic base are found for the anodic activation of titanium in the molten electrolyte under study.

Effect of ripple loads on sustained-load cracking in titanium alloys

International Nuclear Information System (INIS)

Pao, P.S.; Meyn, D.A.; Bayles, R.A.; Feng, C.R.; Yoder, G.R.

1995-01-01

In the present paper, the authors have extended their study on the effect of the ripple loads on the sustained-load cracking (SLC) behavior of two titanium alloys, Ti-6Al-4V (an α-β alloy) and Ti-15V-3Cr-3Al-3Sn (a β-α alloy), in an ambient air environment. The methodology which has been used successfully to treat ripple effects on stress-corrosion cracking (SCC) is employed again to address the influence of ripple loads on sustained-load cracking. Ripple loads can significantly reduce the apparent sustained load cracking resistance of titanium alloys in a relatively benign environment such as ambient air. For a ripple-load amplitude equal to 5% of the sustained load, the ripple-load cracking thresholds (K IRLC ) of beta-annealed Ti-6Al-4V and Ti-15V-3Cr-3al-3Sn are less than half of the respective sustained-load cracking thresholds (K ISLC ). The extent of ripple-load degradation for these alloys in ambient air -- relative to K ISLC , were found comparable to those observed in a much more aggressive 3.5% NaCl aqueous solution

Progress on sputter-deposited thermotractive titanium-nickel films

International Nuclear Information System (INIS)

Grummon, D.S.; Hou Li; Zhao, Z.; Pence, T.J.

1995-01-01

It is now well established that titanium-nickel alloys fabricated as thin films by physical vapor deposition can display the same transformation and shape-memory effects as their ingot-metallurgy counterparts. As such they may find important application to microelectromechanical and biomechanical systems. Furthermore, we show here that titanium-nickel films may be directly processed so as to possess extremely fine austenite grain size and very high strength. These films display classical transformational superelasticity, including high elastic energy storage capacity, the expected dependence of martensite-start temperature on transformation enthalpy, and large, fully recoverable anelastic strains at temperatures above A f . Processing depends on elevated substrate temperatures during deposition, which may be manipulated within a certain range to control both grain size and crystallographic texture. It is also possible to deposit crystalline titanium-nickel films onto polymeric substrates, making them amenable to lithographic patterning into actuator elements that are well-suited to electrical excitation of the martensite reversion transformation. Finally, isothermal annealing of nickel-rich films, under conditions of controlled extrinsic residual stress, leads to topotaxial orientation of Ni 4 Ti 3 -type precipitates, and the associated possibility of two-way memory effects. Much work remains to be done, especially with respect to precise control of composition. (orig.)

Titanium Dioxide Nanoparticles: a Risk for Human Health?

Science.gov (United States)

Grande, Fedora; Tucci, Paola

2016-01-01

Titanium dioxide (TiO2) is a natural oxide of the element titanium with low toxicity, and negligible biological effects. The classification as bio-inert material has given the possibility to normal-sized (>100 nm) titanium dioxide particles (TiO2-NPs) to be extensively used in food products and as ingredients in a wide range of pharmaceutical products and cosmetics, such as sunscreens and toothpastes. Therefore, human exposure may occur through ingestion and dermal penetration, or through inhalation route, during both the manufacturing process and use. In spite of the extensively use of TiO2-NPs, the biological effects and the cellular response mechanisms are still not completely elucidated and thus a deep understanding of the toxicological profile of this compound is required. The main mechanism underlining the toxicity potentially triggered by TiO2-NPs seems to involve the reactive oxygen species (ROS) production, resulting in oxidative stress, inflammation, genotoxicity, metabolic change and potentially carcinogenesis. The extent and type of cell damage strongly depend on chemical and physical characteristics of TiO2-NPs, including size, crystal structure and photo-activation. In this mini-review, we would like to discuss the latest findings on the adverse effects and on potential human health risks induced by TiO2-NPs exposure.

Creating nanoshell on the surface of titanium hydride bead

Directory of Open Access Journals (Sweden)

PAVLENKO Vyacheslav Ivanovich

2016-12-01

Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

Orthodontic buccal tooth movement by nickel-free titanium-based shape memory and superelastic alloy wire.

Science.gov (United States)

Suzuki, Akihiro; Kanetaka, Hiroyasu; Shimizu, Yoshinaka; Tomizuka, Ryo; Hosoda, Hideki; Miyazaki, Shuichi; Okuno, Osamu; Igarashi, Kaoru; Mitani, Hideo

2006-11-01

To examine the mechanical properties and the usefulness of titanium-niobium-aluminum (Ti-Nb-Al) wire in orthodontic tooth movement as compared with nickel-titanium (Ni-Ti) wire. The load deflection of expansion springs was gauged with an original jig. The gradient of the superelastic region was measured during the unloading process. Expansion springs comprising the two types of alloy wires were applied to upper first molars of rats. The distance between the first molars was measured with micrometer calipers. The force magnitude of the Ti-Nb-Al expansion spring was lower than that of the Ni-Ti expansion spring over the entire deflection range. The initial force magnitude and the gradient in the superelastic region of the Ti-Nb-Al expansion springs were half those of the Ni-Ti expansion springs. Thus, Ti-Nb-Al expansion springs generated lighter and more continuous force. Tooth movement in the Ni-Ti group proceeded in a stepwise fashion. On the other hand, tooth movement in the Ti-Nb-Al group showed relatively smooth and continuous progression. At 17 days after insertion of expansion springs, there were no significant differences between the Ti-Nb-Al and Ni-Ti groups in the amount of tooth movement. These results indicate that Ti-Nb-Al wire has excellent mechanical properties for smooth, continuous tooth movement and suggest that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti wire.

Irradiation creep and creep rupture of titanium-modified austenitic stainless steels and their dependence on cold work level

International Nuclear Information System (INIS)

Garner, F.A.; Hamilton, M.L.; Eiholzer, C.R.; Toloczko, M.B.; Kumar, A.S.

1991-11-01

A titanium-modified austenitic type stainless steel was tested at three cold work levels to determine its creep and creep rupture properties under both thermal aging and neutron irradiation conditions. Both the thermal and irradiation creep behavior exhibit a complex non-monotonic relationship with cold work level that reflects the competition between a number of stress-sensitive and temperature-dependent microstructural processes. Increasing the degree of cold work to 30% from the conventional 20% level was detrimental to its performance, especially for applications above 550 degrees c. The 20% cold work level is preferable to the 10% level, in terms of both in-reactor creep rupture response and initial strength

Storage characteristics of hydrogen by titanium

International Nuclear Information System (INIS)

Lee, S. H.; Kang, H. S.; Back, S. W.; Choi, H. J.; Kim, K. R.; An, D. H.; Lee, H. S.; Jung, H. S.

2000-01-01

Hydrogen absorption experiments were performed by the sponge, strip and rod types of titanium(Ti) for investigating the absorption characteristics of hydrogen. From experimental results, Ti sponge showed the high hydrogen absorption capacity inspite of low reaction temperature(25 .deg. C), the H/M, which mean the capacity of hydrogen absorption was measured 2.0 for Ti sponge at 25 .deg. C. However, in case of strip and rod type of Ti, the hydrogen absorption capacities were very low in the experimental condition of 25 .deg. C. The pulverizing phenomena after metal hydriding reaction was observed in both Ti strip and Ti rod. However, the pulverizing phenomena was not observed in the Ti sponges because of high surface area

Mechanism of isotactic styrene polymerization with a C 6F 5-substituted bis(phenoxyimine) titanium system

KAUST Repository

Caporaso, Lucia; Loria, Marianna; Mazzeo, Mina; Michiue, Kenji; Nakano, Takashi; Fujita, Terunori; Cavallo, Luigi

2012-01-01

We report a combined, experimental and theoretical, study of styrene polymerization to clarify the regio- and stereocontrol mechanism operating with a C 6F 5-substituted bis(phenoxyimine) titanium dichloride complex. Styrene homopolymerization, styrene-propene and styrene-ethene-propene copolymerizations have been carried out to this aim. A combination of 13C NMR analysis of the chain-end groups and of the microstructure of the homopolymers and copolymers reveals that styrene polymerization is highly regioselective and occurs prevalently through 2,1-monomer insertion. DFT calculations evidenced that steric interaction between the growing chain and the monomer in the transition state insertion stage is at the origin of this selectivity. The formation of isotactic polystyrene with a chain-end like microstructure is rationalized on the base of a mechanism similar to that proposed for the syndiospecific propene polymerization catalyzed by bis(phenoxyimine) titanium dichloride complexes. Finally, a general stereocontrol mechanism operative in olefin polymerization with this class of complexes is proposed. © 2012 American Chemical Society.

Mechanism of isotactic styrene polymerization with a C 6F 5-substituted bis(phenoxyimine) titanium system

KAUST Repository

Caporaso, Lucia

2012-11-13

We report a combined, experimental and theoretical, study of styrene polymerization to clarify the regio- and stereocontrol mechanism operating with a C 6F 5-substituted bis(phenoxyimine) titanium dichloride complex. Styrene homopolymerization, styrene-propene and styrene-ethene-propene copolymerizations have been carried out to this aim. A combination of 13C NMR analysis of the chain-end groups and of the microstructure of the homopolymers and copolymers reveals that styrene polymerization is highly regioselective and occurs prevalently through 2,1-monomer insertion. DFT calculations evidenced that steric interaction between the growing chain and the monomer in the transition state insertion stage is at the origin of this selectivity. The formation of isotactic polystyrene with a chain-end like microstructure is rationalized on the base of a mechanism similar to that proposed for the syndiospecific propene polymerization catalyzed by bis(phenoxyimine) titanium dichloride complexes. Finally, a general stereocontrol mechanism operative in olefin polymerization with this class of complexes is proposed. © 2012 American Chemical Society.

Selective complexometric determination of titanium(IV) using sodium potassium tartrate or ascorbic acid as masking agent

International Nuclear Information System (INIS)

Sreekumar, N.V.; Bhat, N.G.; Narayana, B.; Nazareth, R.A.; Hegde, P.; Manjunatha, B.R.

2003-01-01

A simple, rapid and accurate complexometric method is proposed for the determination of titanium(IV) where sodium potassium tartrate or ascorbic acid were used as masking agents. In the presence of diverse metal ions, titanium is first complexed with excess of EDTA and surplus EDTA is then titrated at pH 5-6 with zinc sulfate, xylenol orange being used as indicator. An excess of 5 % aqueous sodium potassium tartrate is then added to displace the complexed EDTA from the Ti-EDTA complex quantitatively, which is titrated with zinc sulfate. Also, ascorbic acid may be used as the releasing agent. The methods work well in the range 1-53 mg of Ti(IV) for sodium potassium tartrate with relative errors ± 0.28 % and standard deviations 0.16 mg. For ascorbic acid the range is 1.00-30.00 mg of Ti(IV) with relative errors of ± 0.40 % and standard deviations of 0.05 mg. (author)

Interaction between titanium and sulfuric acid in the electrodeposition of chalcogenide semiconductors

International Nuclear Information System (INIS)

Ortega, J.

1992-01-01

Some chalcogenide electrodeposition problems in the cathodic potential range from -0.30 V to-0.65 V vs SCE may be related to the Titanium corrosion-passivation process in aqueous solutions of sulfuric acid. This feature was discovered accidentally when it was attempted to electrodeposit Cd-Hg-Te compounds from a ternary plating bath; an anodic current of about 10 m/cm 2 was produced in the Titanium cathode at -0.50 V vs SCE, while at -0.40 and -0.60 V vs SCE the current was cathodic. In order to explain this feature, a first study has been carried out to determine the influence of the temperature and sulfuric acid concentration on the passivation current density, passivation potential and Flade potential for passivation. From Arrhenius plots of the passivation currents an apparent activation energy of 63.8 kJ/mole for Titanium passivation in sulfuric acid at -0.50 V vs SCE was obtained. The electrochemical stability of passivated Titanium was explained by assuming that the oxide film formed exhibits n-type semiconducting character, since passivation data was in good agreement with interfacial energetics for n-TiO 2 in aqueous solutions of sulfuric acid.(Author)

Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (I) - Effect of Type and Flow Rate of Shielding Gases on Weldability -

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Do; Kim, Ji Sung [Korea Maritime and Ocean Univ., Busan (Korea, Republic of)

2016-12-15

In this study, welding of pure titanium was carried out by using a continuous wave fiber laser with a maximum output of 6.3 kW. Because brittle regions form easily in titanium as a result of oxidation or nitriding, the weld must be protected from the atmosphere by using an appropriate shielding gas. Experiments were performed by changing the type and the flow rate of shielding gases to obtain the optimal shielding condition, and the weldability was then evaluated. The degree of oxidation and nitriding was distinguished by observing the color of beads, and weld microstructure was observed by using an optical microscope and a scanning electron microscope. The mechanical properties of the weld were examined by measuring hardness. When the weld was oxidized or nitrified, the bead color was gray or yellow, and the oxygen or nitrogen content in the bead surface and overall weld tended to be high, as a result of which the hardness of the weld was thrice that of the base metal. A sound silvery white bead was obtained by using Ar as the shielding gas.

Texturing in titanium grade 2 surface irradiate with ultrashort pulse laser

International Nuclear Information System (INIS)

Nogueira, Alessandro Francelino

2015-01-01

The texturing laser micromachining is an important alternative to improve the bonding adhesion between composites and titanium, which are applied to structural components in the aerospace industry. The texturing running on titanium plates is due to the fact that the preferred joining technique for many composite materials is the adhesive bonding. In this work, titanium plates were texturized using laser ultrashort pulses temporal widths of femtoseconds. This process resulted in minimal heat transfer to the material, avoiding deformation of the titanium plate surface as well as the formation of resolidified material in the ablated region. These drawbacks have occurred with the use of nanoseconds pulses. Were performed three types of texturing using laser with femtosecond pulses, with variations in the distances between the machined lines. The analysis of the obtained surfaces found that the wettability increases when there is the increased distance between the texturing lines. Advancing in the analysis by optical profilometry of textured surfaces was observed that there is substantial increase in the volume available for penetration of structural adhesive when the distances between the textured lines are diminished. In tensile tests conducted it was observed that there is an increase in shear strength of the adhesive joint by reducing the distance between the textured lines. (author)

Titanium electroplating of copper in molten salt media

International Nuclear Information System (INIS)

Renaud, Denis

1985-01-01

After a bibliographical survey on electroplating in molten salt media and on the electrolytic production of titanium, the author explains the reasons for the choice of the LiF-NaF-KF eutectic mix as solvent. He recalls the main properties which are used, and describes the conventional and convolutional processing of data obtained by linear volt-amperometry. He presents the electrolyte preparation mode which takes into account the existence of titanium ions with intermediate oxidation degree, and the reactivity of titanium with oxygenated species. Experimental results are discussed. Then, after the study of the mechanism of reduction of trivalent titanium into titanium on molybdenum (intermetallic diffusion is here negligible), he reports the study of this mechanism on copper (it is a more complicated situation, due to combinations between titanium and copper). The effect of different parameters (electrolyte purity, current density, electrode potential and temperature) is interpreted in order to identify optimal conditions for titanium electroplating of copper [fr

Laser shock peening of titanium 6-4 alloy

International Nuclear Information System (INIS)

Brar, N.S.; Hopkins, A.; Laber, M.W.

2000-01-01

Laser shock peening of titanium 6-4 has been shown to improve its high cycle fatigue life. Residual compressive stresses generated on the surface of titanium 6-4, as a result of laser shocking, have shown dramatic improvement in the performance of aircraft turbine blades. Laser shocking of titanium was carried out with a 20 ns pulse width, 50 joule pulsed laser, operated by LSP Technologies, Columbus, OH. Titanium disks, 20-mm in diameter, and ranging in thicknesses from zero (bare LiF) to 3-mm were subjected to laser shock to monitor amplitude and temporal stress profiles of the pulsed laser. Laser shock stress amplitudes on the back of titanium disks were monitored with VISAR using LiF as the window material. The peak shock stress produced in LiF (titanium thickness zero) was measured to be 16±1 GPa. The laser shock amplitude decays to about 2.7 GPa while propagating through 3-mm thick disk of titanium 6-4

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

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.

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.

Strength and structure of nanocrystalline titanium

International Nuclear Information System (INIS)

Noskova, N.I.; Pereturina, I.A.; Elkina, O.A.; Stolyarov, V.V.

2004-01-01

Investigation results on strength and plasticity of nanocrystalline titanium VT-1 are presented. Specific features of plastic deformation on tension of this material specimens in an electron microscope column are studied in situ. It is shown that nanocrystalline titanium strength and plasticity at room temperature are dependent on the structure and nanograin size. It is revealed that deformation processes in nanocrystalline titanium are characterized by activation of deformation rotational modes and microtwinning [ru

Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

Directory of Open Access Journals (Sweden)

Waldemar Hoffmann

2014-06-01

Full Text Available While calcium phosphate–based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel–titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel–titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel–titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel–titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel–titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel–titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold’s pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel–titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used

Coating of the orthopaedic titanium alloys with sol-gel derived hydroxyapatite

International Nuclear Information System (INIS)

Milev, A.; Green, D.; Chai, C.S.; Ben-Nissan, B.

1999-01-01

Hydroxyapatite (HAp) is known to be both biocompatible and bioactive material, however, due to its poor mechanical properties and design limitations is not suitable for applying as a load bearing implant. This could be overcome by using appropriate metallic substrates covered with HAp, derived via different techniques. These coatings allow improved adhesion strength of the load bearing substrate to the bone, resulting in shorter healing periods as well as predictable behaviour of the implant for longer periods of time. There are different techniques of producing HAp appropriate for coating purposes. Due to the small particle size of the grains derived, sol-gel route is preferable where lower sintering temperatures are of primary importance. For better adhesion between substrate and hydroxyapatite coating, the surface of titanium substrate, in this study, was converted to titanium nitride and/or oxynitride. Sintering temperatures of 900 deg C have been used for producing crystalline HAp coatings. The control of sol-gel solutions and the analysis of the coatings were carried out using XRD, SEM and DTA techniques. Results obtained indicate high quality HAp coatings can be produced on titanium substrates especially with complex shapes that benefits over the other coating methods

Elastic modulus, microplastic properties and durability of titanium alloys for biomedical applications

Czech Academy of Sciences Publication Activity Database

Betekhtin, V. I.; Kolobov, Yu. R.; Golosova, O. A.; Dvořák, Jiří; Sklenička, Václav; Kardashev, B. K.; Kadomtsev, A. G.; Narykova, M. V.; Ivanov, M. B.

2016-01-01

Roč. 45, 1-2 (2016), s. 42-51 ISSN 1606-5131 Institutional support: RVO:68081723 Keywords : Creep * Elastic moduli * Plastic flow * Beta-type titanium alloys * Biomedical applications Subject RIV: JG - Metallurgy Impact factor: 2.500, year: 2016

Managing innovation complexity: About the co-existence of innovation types

OpenAIRE

Pohlmann, Philipp Adrian

2014-01-01

The purpose of this study is to contribute to the changing innovation management literature by providing an overview of different innovation types and organizational complexity factors. Aiming at a better understanding of effective innovation management, innovation and complexity are related to the formulation of an innovation strategy and interaction between different innovation types is further explored. The chosen approach in this study is to review the existing literature on different inn...

Synchrotron X-ray CT characterization of titanium parts fabricated by additive manufacturing. Part I. Morphology.

Science.gov (United States)

Scarlett, Nicola Vivienne Yorke; Tyson, Peter; Fraser, Darren; Mayo, Sheridan; Maksimenko, Anton

2016-07-01

Synchrotron X-ray tomography has been applied to the study of titanium parts fabricated by additive manufacturing (AM). The AM method employed here was the Arcam EBM(®) (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V), as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. Samples were chosen to examine the effect of build direction and complexity of design on the surface morphology and final dimensions of the piece.

A study of chitosan hydrogel with embedded mesoporous silica nanoparticles loaded by ibuprofen as a dual stimuli-responsive drug release system for surface coating of titanium implants.

Science.gov (United States)

Zhao, Pengkun; Liu, Hongyu; Deng, Hongbing; Xiao, Ling; Qin, Caiqin; Du, Yumin; Shi, Xiaowen

2014-11-01

In this study, the complex pH and electro responsive system made of chitosan hydrogel with embedded mesoporous silica nanoparticles (MSNs) was evaluated as a tunable drug release system. As a model drug, ibuprofen (IB) was used; its adsorption in MSNs was evidenced by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TG). In order to prepare the complex drug release system, the loaded particles IB-MSNs were dispersed in chitosan solution and then the complex IB-MSNs/chitosan film of 2mm thickness was deposited as a hydrogel on the titanium electrode. The codeposition of components was performed under a negative biasing of the titanium electrode at -0.75 mA/cm2 current density during 30 min. The IB release from the IB-MSNs/chitosan hydrogel film was studied as dependent on pH of the release media and electrical conditions applied to the titanium plate. When incubating the complex hydrogel film in buffers with different pH, the IB release followed a near zero-order profile, though its kinetics varied. Compared to the spontaneous IB release from the hydrogel in 0.9% NaCl solution (at 0 V), the application of negative biases to the coated titanium plate had profound effluences on the release behavior. The release was retarded when -1.0 V was applied, but a faster kinetics was observed at -5.0 V. These results imply that a rapid, mild and facile electrical process for covering titanium implants by complex IB-MSNs/chitosan hydrogel films can be used for controlled drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Kinetic study of synthesis of Titanium carbide by methano thermal reduction of Titanium dioxide

International Nuclear Information System (INIS)

Alizadeh, R.; Ostrovski, O.

2011-01-01

Reduction of the Titanium dioxide, TiO 2 , by methane was investigated in this work. The thermodynamic of reaction was examined and found favorable. The reaction of titanium dioxide with methane was carried out in the temperature range 1150 d egree C to 1450 d egree C at atmospheric pressure with industrial high porosity pellets prepared from titanium dioxide powder. The evolved gas analyzing method was used for determination of the extent of reduction rate. The gas products of the reaction are mostly CO and trace amount of CO 2 and H 2 O. The synthesized product powder was characterized by X-ray diffraction for elucidating solid phase compositions. The effect of varying temperature was studied during the reduction. The conversion-time data have been interpreted by using the grain model. For first order reaction with respect to methane concentration, the activation energy of titanium dioxide reduction by methane is found to be 51.4 kcal/g mole. No detailed investigation of kinetic and mechanism of the reaction was reported in literatures.

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

Science.gov (United States)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Synthesis and Exploratory Catalysis of 3d Metals: Group-Transfer Reactions, and the Activation and Functionalization of Small Molecules Including Greenhouse Gases

Energy Technology Data Exchange (ETDEWEB)

Mindiola, Daniel J.

2014-05-07

Our work over the past three years has resulted in the development of electron rich and low-coordinate vanadium fragments, molecular nitrides of vanadium and parent imide systems of titanium, and the synthesis of phosphorus containing molecules of the 3d transition metal series. Likewise, with financial support from BES Division in DOE (DE-FG02-07ER15893), we now completed the full characterization of the first single molecular magnet (SMM) of Fe(III). We demonstrated that this monomeric form of Fe(III) has an unusual slow relaxation of the magnetization under zero applied field. To make matters more interesting, this system also undergoes a rare example of an intermediate to high-spin transition (an S = 3/2 to S = 5/2 transition). In 2010 we reported the synthesis of the first neutral and low-coordinate vanadium complexes having the terminal nitride functionality. We have now completed a full study to understand formation of the nitride ligand from the metastable azide precursor, and have also explored the reactivity of the nitride ligand in the context of incomplete and complete N-atom transfer. During the 2010-2013 period we also discovered a facile approach to assemble low-coordinate and low-valent vanadium(II) complexes and exploit their multielectron chemistry ranging from 1-3 electrons. Consequently, we can now access 3d ligand frameworks such as cyclo-P3 (and its corresponding radical anion), nitride radical anions and cations, low-coordinate vanadium oxo’s, and the first example of a vanadium thionitrosyl complex. A cis-divacant iron(IV) imido having some ligand centered radical has been also discovered, and we are in the process of elucidating its electronic structure (in particular the sign of zero field splitting and the origin of its magnitude), bonding and reactivity. We have also revisited some paramagnetic and classic metallocene compounds with S >1/2 ground states in order to understand their reactivity patterns and electronic structure. Lastly

In situ formation of titanium carbide using titanium and carbon-nanotube powders by laser cladding

International Nuclear Information System (INIS)

Savalani, M.M.; Ng, C.C.; Li, Q.H.; Man, H.C.

2012-01-01

Titanium metal matrix composite coatings are considered to be important candidates for high wear resistance applications. In this study, TiC reinforced Ti matrix composite layers were fabricated by laser cladding with 5, 10, 15 and 20 wt% carbon-nanotube. The effects of the carbon-nanotube content on phase composition, microstructure, micro-hardness and dry sliding wear resistance of the coating were studied. Microstructural observation using scanning electron microscopy showed that the coatings consisted of a matrix of alpha-titanium phases and the reinforcement phase of titanium carbide in the form of fine dendrites, indicating that titanium carbide was synthesized by the in situ reaction during laser irradiation. Additionally, measurements on the micro-hardness and dry sliding wear resistance of the coatings indicated that the mechanical properties were affected by the amount of carbon-nanotube in the starting precursor materials and were enhanced by increasing the carbon-nanotube content. Results indicated that the composite layers exhibit high hardness and excellent wear resistance.

In situ formation of titanium carbide using titanium and carbon-nanotube powders by laser cladding

Energy Technology Data Exchange (ETDEWEB)

Savalani, M.M., E-mail: mmfsmm@inet.polyu.edu.hk [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University (Hong Kong); Ng, C.C.; Li, Q.H.; Man, H.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University (Hong Kong)

2012-01-15

Titanium metal matrix composite coatings are considered to be important candidates for high wear resistance applications. In this study, TiC reinforced Ti matrix composite layers were fabricated by laser cladding with 5, 10, 15 and 20 wt% carbon-nanotube. The effects of the carbon-nanotube content on phase composition, microstructure, micro-hardness and dry sliding wear resistance of the coating were studied. Microstructural observation using scanning electron microscopy showed that the coatings consisted of a matrix of alpha-titanium phases and the reinforcement phase of titanium carbide in the form of fine dendrites, indicating that titanium carbide was synthesized by the in situ reaction during laser irradiation. Additionally, measurements on the micro-hardness and dry sliding wear resistance of the coatings indicated that the mechanical properties were affected by the amount of carbon-nanotube in the starting precursor materials and were enhanced by increasing the carbon-nanotube content. Results indicated that the composite layers exhibit high hardness and excellent wear resistance.

Influence of titanium on the tempering structure of austenitic steels

International Nuclear Information System (INIS)

Ghuezaiel, M.J.

1985-10-01

The microstructure of titanium-stabilized and initially deformed (approximately 20%) austenitic stainless steels used in structures of fast neutrons reactors has been studied after one hour duration annealings (500 0 C) by X-ray diffraction, optical microscopy, microhardness and transmission electron microscopy. The studied alloys were either of industrial type CND 17-13 (0.23 to 0.45 wt% Ti) or pure steels (18% Cr, 14% Ni, 0 or 0.3 wt% Ti). During tempering, the pure steels presented some restauration before recristallization. In the industrial steels, only recristallization occurred, and this only in the most deformed steel. Precipitation does not occur in the titanium-free pure steel. In industrial steels, many intermetallic phases are formed when recristallization starts [fr

Investigation of behaviour of the hexanite-R during microcutting of titanium and steel

International Nuclear Information System (INIS)

Samsonov, G.V.; Pilyankevich, A.N.; Adamovskij, A.A.; Bochko, A.V.; Dzhamarov, S.S.; Balan, T.R.

1976-01-01

A study has been made of hexanite-R in the process of microcutting titanium and steel, whose conditions simulate the behaviour of the grain of the abrasive disk. It is shown that in the grindings of the metals with high cutting speeds the deciding influence on the grain wear is produced by the chemical activity of the grain with respect to the metal under treatment, whereas the initial hardness of the abrasive material does not exert any appreciable effect on the wear. The adhesion type of hexanite-R wear will be typical of titanium grinding, and the abrasive type - of steel grinding. In the abrasive-metal friction couple the combined action of pressures and temperature causes the electron exchange between the contacting couples, which explains the wear of the materials brought into contact

Experimental Technique of Titanium Fire in Aero-engine

Directory of Open Access Journals (Sweden)

MI Guangbao

2016-06-01

Full Text Available Titanium fire is the typical catastrophic fault in the aero-engine. Aiming at the urgent demand for experimental technique of titanium fire from advanced high thrust-weight ratio aero-engine, the combustion technology and theory of titanium alloy based on friction oxygen concentration method (FOC were systematically studied. The evaluation method of fireproof property and the friction ignition model were built, and the fireproof mechanism was illustrated. By generalizing recent progress in experimental technique of titanium fire from three levels, including evolutionary rule, mechanism and prevention and control technology, the ideas and directions of experimental technique associated with the application research of titanium fire in the future were proposed, namely overall evaluation of fireproof property close to air flow environment of the aero-engine, prediction model of fireproof property and experimental verification of fireproof technique under the air flow environment of aero-engine. It is necessary to establish the prevention system of titanium fire in aero-engine, which contributes to the realization of "full titanium" in compressor and to the increase of high thrust-weight ratio.

Half-and-Half Palatoplasty.

Science.gov (United States)

Han, Hyun Ho; Kang, In Sook; Rhie, Jong Won

2014-08-01

A 14-month-old child was diagnosed with a Veau Class II cleft palate. Von Langenbeck palatoplasty was performed for the right palate, and V-Y pushback palatoplasty was performed for the left palate. The child did not have a special problem during the surgery, and the authors were able to elongate the cleft by 10 mm. Contrary to preoperative concerns regarding the hybrid use of palatoplasties, the uvula and midline incisions remained balanced in the middle. The authors named this combination method "half-and-half palatoplasty" and plan to conduct a long-term follow up study as a potential solution that minimizes the complications of palatoplasty.

Synthesis and reactivity of bis(tetramethylcyclopentadienyl) yttrium metallocenes including the reduction of Me(3)SiN(3) to [(Me(3)Si)(2)N](-) with [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)).

Science.gov (United States)

Lorenz, Sara E; Schmiege, Benjamin M; Lee, David S; Ziller, Joseph W; Evans, William J

2010-07-19

The metallocene precursors needed to provide the tetramethylcyclopentadienyl yttrium complexes (C(5)Me(4)H)(3)Y, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), and [(C(5)Me(4)H)(2)Y(mu-H)](2) for reactivity studies have been synthesized and fully characterized, and their reaction chemistry has led to an unexpected conversion of an azide to an amide. (C(5)Me(4)H)(2)Y(mu-Cl)(2)K(THF)(x), 1, synthesized from YCl(3) and KC(5)Me(4)H reacts with allylmagnesium chloride to make (C(5)Me(4)H)(2)Y(eta(3)-C(3)H(5)), 2, which is converted to [(C(5)Me(4)H)(2)Y][(mu-Ph)(2)BPh(2)], 3, with [Et(3)NH][BPh(4)]. Complex 3 reacts with KC(5)Me(4)H to form (C(5)Me(4)H)(3)Y, 4. The reduced dinitrogen complex, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), 5, can be synthesized from either [(C(5)Me(4)H)(2)Y](2)[(mu-Ph)(2)BPh(2)], 3, or (C(5)Me(4)H)(3)Y, 4, with potassium graphite under a dinitrogen atmosphere. The (15)N labeled analogue, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-(15)N(2)), 5-(15)N, has also been prepared, and the (15)N NMR data have been compared to previously characterized reduced dinitrogen complexes. Complex 2 reacts with H(2) to form the corresponding hydride, [(C(5)Me(4)H)(2)Y(mu-H)](2), 6. Complex 5 displays similar reactivity to that of the analogous [(C(5)Me(4)H)(2)Ln(THF)](2)(mu-eta(2):eta(2)-N(2)) complexes (Ln = La, Lu), with substrates such as phenazine, anthracene, and CO(2). In addition, 5 reduces Me(3)SiN(3) to form (C(5)Me(4)H)(2)Y[N(SiMe(3))(2)], 7.

Relationship between surface properties (roughness, wettability) of titanium and titanium alloys and cell behaviour

International Nuclear Information System (INIS)

Ponsonnet, L.; Reybier, K.; Jaffrezic, N.; Comte, V.; Lagneau, C.; Lissac, M.; Martelet, C.

2003-01-01

Cell attachment and spreading to titanium-based alloy surfaces is a major parameter in implant technology. In this paper, substratum surface hydrophobicity, surface free energy, interfacial free energy and surface roughness were investigated to ascertain which of these parameters is predominant in human fibroblast spreading. Two methods for contact angle measurement were compared: the sessile drop method and the captive bubble two-probe method. The relationship between surface roughness and the sessile drop contact angles of various engineered titanium surfaces such as commercial pure titanium (cp-Ti), titanium-aluminium-vanadium alloy (Ti-6Al-4V), and titanium-nickel (NiTi), was shown. Surface free energy (SFE) calculations were performed from contact angles obtained on smooth samples based on the same alloys in order to eliminate the roughness effect. SFE of the surfaces have been calculated using the Owens-Wendt (OW) and Van Oss (VO) approaches with the sessile drop method. The OW calculations are used to obtain the dispersive (γ d ) and polar (γ p ) component of SFE, and the VO approach allows to reach the apolar (γ LW ) and the polar acid-base component (γ ab ) of the surface. From captive bubble contact angle experiments (air or octane bubble under water), the interfacial free energy of the different surfaces in water was obtained. A relationship between cell spreading and the polar component of SFE was found. Interfacial free energy values were low for all the investigated surfaces indicating good biocompatibility for such alloys

Identification of RNA species in the RNA-toxin complex and structure of the complex in Clostridium botulinum type E.

Science.gov (United States)

Kitamura, Masaru

2002-02-15

Clostridium botulinum type E toxin was isolated in the form of a complex with RNA(s) from bacterial cells. Characterization of the complexed RNA remains to be elucidated. The RNA is identified here as ribosomal RNA (rRNA) having 23S and 16S components. The RNA-toxin complexes were found to be made up of three types with different molecular sizes. The three types of RNA-toxin complex are toxin bound to both the 23S and 16S rRNA, toxin bound to the 16S rRNA and a small amount of 23S rRNA, and toxin bound only to the 16S rRNA. ©2002 Elsevier Science (USA).

Analogy and differences between aluminium and titanium electrowinning

CSIR Research Space (South Africa)

Van Vuuren, DS

2006-09-01

Full Text Available larger market. The authors have tested this route experimentally, but could not produce pure titanium. The failure of electrowinning pure, molten titanium has been interpreted in terms of the analogy and differences between aluminium and titanium...

Direct dynamic synthesis of nanodispersed phases of titanium oxides upon sputtering of electrodischarge titanium plasma into an air atmosphere

Science.gov (United States)

Sivkov, A. A.; Gerasimov, D. Yu.; Nikitin, D. S.

2017-01-01

Experimental investigations of the possibility of directly synthesizing nanodispersed crystalline phases of titanium dioxides with rutile and anatase structures in a hypervelocity jet of electroerosion plasma generated by a coaxial magnetoplasma accelerator with titanium electrodes are presented. A powder product containing nanosized polymorphic phases of titanium dioxide with a spherical shape of particles has been manufactured.

Development of a Compact Maglev Centrifugal Blood Pump Enclosed in a Titanium Housing

Science.gov (United States)

Pai, Chi Nan; Shinshi, Tadahiko; Asama, Junichi; Takatani, Setsuo; Shimokohbe, Akira

A compact centrifugal blood pump consisting of a controlled two-degrees-of-freedom radial magnetic bearing and a brushless DC motor enclosed in a titanium housing has been developed for use as an implantable ventricular assist device. The magnetic bearing also supports axial and angular motions of the impeller via a magnetic coupling. The top housing is made of pure titanium, while the impeller and the stator are coated with pure titanium and Ti-6Al-7Nb, respectively, to improve the biocompatibility of the pump. The combination of pure titanium and titanium alloy was chosen because of the sensitivity of eddy current type displacement sensors through the intervening conducting wall. The dimensions of the pump are 69.0 mm in diameter and 28.5 mm in height. During a pump performance test, axial shifting of the impeller due to hydraulic forces led to variations in the rotational positioning signal, causing loss of control of the rotational speed. This problem was solved by conditioning the rotational positioning signal. With a flow rate of 5 l/min against a head pressure of 100 mmHg, the power consumption and efficiency of the pump were 5.5 W and 20%, respectively. Furthermore, the hemolysis of the blood pump was 43.6% lower when compared to that of a commercially available pump.

Titanium application to power plant condensers

International Nuclear Information System (INIS)

Itoh, H.

1987-01-01

Recently, the growth of operating performance and construction plan of titanium-tubed condensers in thermal and unclear power plants has been very impressive. High-quality, thinner welded titanium tubes used for cooling tubes, matching design specifications of condensers, have been stably supplied through mass production. It now can be said that various technical problems for titanium-tubed condensers have been solved, but data on operating performance in large-scale commercial plants are still scarce, and site-by-site information needs be exchanged more frequently and on a larger scale. Projects to replace existing condenser cooling tubes with those of corrosion-resistant titanium have been actively furthered, with the only remaining barrier to full employment being cost effectiveness. It is hoped that condenser and tube manufacturers will conduct more joint value analyses

Stress corrosion cracking of titanium alloys

Science.gov (United States)

May, R. C.; Beck, F. H.; Fontana, M. G.

1971-01-01

Experiments were conducted to study (1) the basic electrochemical behavior of titanium in acid chloride solutions and (2) the response of the metal to dynamic straining in the same evironment. The aim of this group of experiments was to simulate, as nearly as possible, the actual conditions which exist at the tip of a crack. One of the foremost theories proposed to explain the propagation of stress corrosion cracks is a hydrogen embrittlement theory involving the precipitation of embrittling titanium hydrides inside the metal near the crack tip. An initial survey of the basic electrochemical literature indicated that surface hydrides play a critical role in the electrochemistry of titanium in acid solutions. A comprehensive analysis of the effect of surface films, particularly hydrides, on the electrochemical behavior of titanium in these solution is presented.

Raman scattering in transition metal compounds: Titanium and compounds of titanium

Energy Technology Data Exchange (ETDEWEB)

Jimenez, J.; Ederer, D.L.; Shu, T. [Tulane Univ., New Orleans, LA (United States)] [and others

1997-04-01

The transition metal compounds form a very interesting and important set of materials. The diversity arises from the many states of ionization the transition elements may take when forming compounds. This variety provides ample opportunity for a large class of materials to have a vast range of electronic and magnetic properties. The x-ray spectroscopy of the transition elements is especially interesting because they have unfilled d bands that are at the bottom of the conduction band with atomic like structure. This group embarked on the systematic study of transition metal sulfides and oxides. As an example of the type of spectra observed in some of these compounds they have chosen to showcase the L{sub II, III} emission and Raman scattering in some titanium compounds obtained by photon excitation.

On the half-life of luminescence signals in dosimetric applications: A unified presentation

Science.gov (United States)

Pagonis, V.; Kitis, G.; Polymeris, G. S.

2018-06-01

Luminescence signals from natural and man-made materials are widely used in dosimetric and dating applications. In general, there are two types of half-lives of luminescence signals which are of importance to experimental and modeling work in this research area. The first type of half-life is the time required for the population of the trapped charge in a single trap to decay to half its initial value. The second type of half-life is the time required for the luminescence intensity to drop to half of its initial value. While there a handful of analytical expressions available in the literature for the first type of half-life, there are no corresponding analytical expressions for the second type. In this work new analytical expressions are derived for the half-life of luminescence signals during continuous wave optical stimulation luminescence (CW-OSL) or isothermal luminescence (ITL) experiments. The analytical expressions are derived for several commonly used luminescence models which are based on delocalized transitions involving the conduction band: first and second order kinetics, empirical general order kinetics (GOK), mixed order kinetics (MOK) and the one-trap one-recombination center (OTOR) model. In addition, half-life expressions are derived for a different type of luminescence model, which is based on localized transitions in a random distribution of charges. The new half-life expressions contain two parts. The first part is inversely proportional to the thermal or optical excitation rate, and depends on the experimental conditions and on the cross section of the relevant luminescence process. The second part is characteristic of the optical and/or thermal properties of the material, as expressed by the parameters in the model. A new simple and quick method for analyzing luminescence signals is developed, and examples are given of applying the new method to a variety of dosimetric materials. The new test allows quick determination of whether a set of

Titanium Metal Powder Production by the Plasma Quench Process

Energy Technology Data Exchange (ETDEWEB)

R. A. Cordes; A. Donaldson

2000-09-01

The goals of this project included the scale-up of the titanium hydride production process to a production rate of 50 kg/hr at a purity level of 99+%. This goal was to be achieved by incrementally increasing the production capability of a series of reactor systems. This methodic approach was designed to allow Idaho Titanium Technologies to systematically address the engineering issues associated with plasma system performance, and powder collection system design and performance. With quality powder available, actual fabrication with the titanium hydride was to be pursued. Finally, with a successful titanium production system in place, the production of titanium aluminide was to be pursued by the simultaneously injection of titanium and aluminum precursors into the reactor system. Some significant accomplishments of the project are: A unique and revolutionary torch/reactor capable of withstanding temperatures up to 5000 C with high thermal efficiency has been operated. The dissociation of titanium tetrachloride into titanium powder and HC1 has been demonstrated, and a one-megawatt reactor potentially capable of producing 100 pounds per hour has been built, but not yet operated at the powder level. The removal of residual subchlorides and adsorbed HC1 and the sintering of powder to form solid bodies have been demonstrated. The production system has been operated at production rates up to 40 pounds per hour. Subsequent to the end of the project, Idaho Titanium Technologies demonstrated that titanium hydride powder can indeed be sintered into solid titanium metal at 1500 C without sintering aids.

The effect of titanium surface treatment on the interfacial strength of titanium – Thermoplastic composite joints

NARCIS (Netherlands)

Su, Yibo; de Rooij, Matthijn; Grouve, Wouter; Akkerman, Remko

2017-01-01

Co-consolidated titanium – carbon fibre reinforced thermoplastic composite hybrid joints show potential for application in aerospace structures. The strength of the interface between the titanium and the thermoplastic composite is crucial for the strength of the entire hybrid joint. Application of a

Lactam inhibiting Streptococcus mutans growth on titanium

International Nuclear Information System (INIS)

Xavier, J.G.; Geremias, T.C.; Montero, J.F.D.; Vahey, B.R.; Benfatti, C.A.M.; Souza, J.C.M.; Magini, R.S.; Pimenta, A.L.

2016-01-01

The aim of this work was to analyze the activity of novel synthetic lactams on preventing biofilm formation on titanium surfaces. Titanium (Ti6Al4V) samples were exposed to Streptococcus mutans cultures in the presence or absence of a synthetic lactam. After 48 h incubation, planktonic growth was determined by spectrophotometry. Biofilm was evaluated by crystal violet staining and colony forming units (CFU·ml −1 ), followed by scanning electron microscopy (SEM). Results showed that the average of adhered viable cells was approximately 1.5 × 10 2 CFU/ml in the presence of lactam and 4 × 10 2 CFU/ml in its absence. This novel compound was considerable active in reducing biofilm formation over titanium surfaces, indicating its potential for the development of antimicrobial drugs targeting the inhibition of the initial stages of bacterial biofilms on dental implants abutments. - Highlights: • A novel synthetic compound is tested on preventing biofilm formation on titanium surfaces • Biofilm inhibition has been achieved on titanium surfaces containing the novel compound. • Planktonic growth of S. mutans was not affected by the presence of lactams on titanium.

Lactam inhibiting Streptococcus mutans growth on titanium

Energy Technology Data Exchange (ETDEWEB)

Xavier, J.G.; Geremias, T.C.; Montero, J.F.D. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-900 (Brazil); Vahey, B.R. [Herman Ostrow School of Dentistry of USC, 925 W 34 St, Los Angeles, CA 90089 (United States); Benfatti, C.A.M.; Souza, J.C.M.; Magini, R.S. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-900 (Brazil); Pimenta, A.L., E-mail: andrea@intelab.ufsc.br [Department of Biologia, ERRMECe, Université de Cergy Pontoise, 2, Av. Adolphe Chauvin 95302 Cergy, Pontoise (France); Integrated Laboratories Technologies (InteLab), Dept. Chemical and Food Engineering (EQA), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-970 (Brazil)

2016-11-01

The aim of this work was to analyze the activity of novel synthetic lactams on preventing biofilm formation on titanium surfaces. Titanium (Ti6Al4V) samples were exposed to Streptococcus mutans cultures in the presence or absence of a synthetic lactam. After 48 h incubation, planktonic growth was determined by spectrophotometry. Biofilm was evaluated by crystal violet staining and colony forming units (CFU·ml{sup −1}), followed by scanning electron microscopy (SEM). Results showed that the average of adhered viable cells was approximately 1.5 × 10{sup 2} CFU/ml in the presence of lactam and 4 × 10{sup 2} CFU/ml in its absence. This novel compound was considerable active in reducing biofilm formation over titanium surfaces, indicating its potential for the development of antimicrobial drugs targeting the inhibition of the initial stages of bacterial biofilms on dental implants abutments. - Highlights: • A novel synthetic compound is tested on preventing biofilm formation on titanium surfaces • Biofilm inhibition has been achieved on titanium surfaces containing the novel compound. • Planktonic growth of S. mutans was not affected by the presence of lactams on titanium.

Comparative study on effects of two different types of titanium dioxide nanoparticles on human neuronal cells.

Science.gov (United States)

Valdiglesias, Vanessa; Costa, Carla; Sharma, Vyom; Kiliç, Gözde; Pásaro, Eduardo; Teixeira, João Paulo; Dhawan, Alok; Laffon, Blanca

2013-07-01

Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a variety of consumer products, including food industry in which they are employed as an additive. The potential toxic effects of these NPs on mammal cells have been extensively studied. However, studies regarding neurotoxicity and specific effects on neuronal systems are very scarce and, to our knowledge, no studies on human neuronal cells have been reported so far. Therefore, the main objective of this work was to investigate the effects of two types of TiO₂ NPs, with different crystalline structure, on human SHSY5Y neuronal cells. After NPs characterization, a battery of assays was performed to evaluate the viability, cytotoxicity, genotoxicity and oxidative damage in TiO₂ NP-exposed SHSY5Y cells. Results obtained showed that the behaviour of both types of NPs resulted quite comparable. They did not reduce the viability of neuronal cells but were effectively internalized by the cells and induced dose-dependent cell cycle alterations, apoptosis by intrinsic pathway, and genotoxicity not related with double strand break production. Furthermore, all these effects were not associated with oxidative damage production and, consequently, further investigations on the specific mechanisms underlying the effects observed in this study are required. Copyright © 2013 Elsevier Ltd. All rights reserved.

Introduction to powder metallurgy processes for titanium manufacturing

International Nuclear Information System (INIS)

Esteban, P. G.; Bolzoni, L.; Ruiz-Navas, E. M.; Gordo, E.

2011-01-01

The development of new extraction processes to produce titanium in powder form leads Powder Metallurgy to an advantage position among the manufacturing processes for titanium. The cost reduction of base material, coupled with the economy of the powder metallurgy processes, give titanium industry the chance to diversify its products, which could lead to production volumes able to stabilise the price of the metal. This work reviews some of the Powder Metallurgy techniques for the manufacturing of titanium parts, and describes the two typical approaches for titanium manufacturing: Blending Elemental and Prealloyed Powders. Among others, conventional pressing and sintering are described, which are compared with cold and hot isostatic pressing techniques. Real and potential applications are described. (Author) 71 refs.

Microwave assisted scalable synthesis of titanium ferrite nanomaterials

Science.gov (United States)

Shukla, Abhishek; Bhardwaj, Abhishek K.; Singh, S. C.; Uttam, K. N.; Gautam, Nisha; Himanshu, A. K.; Shah, Jyoti; Kotnala, R. K.; Gopal, R.

2018-04-01

Titanium ferrite magnetic nanomaterials are synthesized by one-step, one pot, and scalable method assisted by microwave radiation. Effects of titanium content and microwave exposure time on size, shape, morphology, yield, bonding nature, crystalline structure, and magnetic properties of titanium ferrite nanomaterials are studied. As-synthesized nanomaterials are characterized by X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-Vis), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, transmission electron microscopy (TEM), and vibrating sample magnetometer measurements. XRD measurements depict the presence of two phases of titanium ferrite into the same sample, where crystallite size increases from ˜33 nm to 37 nm with the increase in titanium concentration. UV-Vis measurement showed broad spectrum in the spectral range of 250-600 nm which reveals that its characteristic peaks lie between ultraviolet and visible region; ATR-FTIR and Raman measurements predict iron-titanium oxide structures that are consistent with XRD results. The micrographs of TEM and selected area electron diffraction patterns show formation of hexagonal shaped particles with a high degree of crystallinity and presence of multi-phase. Energy dispersive spectroscopy measurements confirm that Ti:Fe compositional mass ratio can be controlled by tuning synthesis conditions. Increase of Ti defects into titanium ferrite lattice, either by increasing titanium precursor or by increasing exposure time, enhances its magnetic properties.

Adaptive mesh refinement in titanium

Energy Technology Data Exchange (ETDEWEB)

Colella, Phillip; Wen, Tong

2005-01-21

In this paper, we evaluate Titanium's usability as a high-level parallel programming language through a case study, where we implement a subset of Chombo's functionality in Titanium. Chombo is a software package applying the Adaptive Mesh Refinement methodology to numerical Partial Differential Equations at the production level. In Chombo, the library approach is used to parallel programming (C++ and Fortran, with MPI), whereas Titanium is a Java dialect designed for high-performance scientific computing. The performance of our implementation is studied and compared with that of Chombo in solving Poisson's equation based on two grid configurations from a real application. Also provided are the counts of lines of code from both sides.

[The bonding characteristic of titanium and RG experiment porcelain].

Science.gov (United States)

Ren, Wei-hong; Guo, Tian-wen; Tian, Jie-mo; Zhang, Yun-long

2003-07-01

To study the bonding characteristic of Titanium and RG experiment porcelain. 5 specimens with a size of 10 mm x 5 mm x 1.4 mm were cast from pure titanium. Then 1 mm of RG experiment opaque and body porcelain were fused on the surface of the titanium specimens. The interface of titanium and porcelain was analyzed with a scanning electron microscope with energy-despersive spectrometry; 6 metal specimens with the size of 25 mm x 3 mm x 0.5 mm were cast from Ni-Cr alloy and a uniform thickness of 1 mm of VMK 99 porcelain was veneered on the central area of 8 mm x 3 mm 18 metal specimens as the same size were cast from pure titanium. The uniform thickness of 1 mm of VITA TITANKERAMIK porcelain, of Noritake super porcelain Ti-22 and of RG experiment porcelain were veneered on every 6 specimens respectively in the central area of 8 mm x 3 mm. The specimens were subjected to a three-point bending test on a load-test machine with a span of 20 mm, then the failure loads were recorded and statistically analysised. The RG porcelain/titanium crown was fabricated by fusing RG opaque porcelain and body porcelain to cast titanium substrate crown. The SEM results show no porosity and crackle were found in the interface. The energy-dispersive spectrometry show that there are Si, Ti and O in the 1 micro m layer between porcelain and titanium, which suggesting titanium and experiment porcelain bonding well. The three point test showed the fracture force for the combinations of titanium/VITA TITANKERAMIK porcelain, titanium/Noritake super porcelain Ti-22 and titanium/RG experiment porcelain were (7.233 +/- 2.539) N, (5.533 +/- 1.199) N and (6.316 +/- 1.433) N respectively. There were not statistically significant differences among them (t test, P porcelain combination (12.733 +/- 3.297) N was significantly greater than those of the cast titanium/porcelain (t test, P > 0.05). The crown was translucent with no crack. RG porcelain is well compatible with titanium.

Formation of titanium nitride layers on titanium metal: Results of XPS and AES investigations

International Nuclear Information System (INIS)

Moers, H.; Pfennig, G.; Klewe-Nebenius, H.; Penzhorn, R.D.; Sirch, M.; Willin, E.

1988-09-01

The reaction of titanium metal with gaseous nitrogen and ammonia at temperatures of 890 0 C leads to the formation of nitridic overlayers on the metallic substrate. The thicknesses of the overlayers increase with increasing reaction time. Under comparable conditions ammonia reacts much slower than nitrogen. XPS and AES depth profile analyses show continuous changes of the in-depth compositions of the overlayers. This can be interpreted in terms of a very irregular thickness of the overlayers, an assumption which is substantiated by local AES analyses and by the observation of a pronounced crystalline structure of the substrate after annealing pretreatment, which can give rise to locally different reaction rates. The depth profile is also influenced by the broad ranges of stability of the titanium nitride phases formed during the reaction. The quantitative analysis of the titanium/nitrogen overlayers by AES is difficult because of the overlap of titanium and nitrogen Auger peaks. In quantitative XPS analysis problems arise due to difficulties in defining Ti 2p peak areas. This work presents practical procedures for the quantitative evaluation by XPS and AES of nitridic overlayers with sufficient accuracy. (orig.) [de

The phosphorylation pattern of bovine heart complex I subunits

DEFF Research Database (Denmark)

Palmisano, Giuseppe; Sardanelli, Anna Maria; Signorile, Anna

2007-01-01

The phosphoproteome of bovine heart complex I of the respiratory chain has been analysed with a procedure based on nondenaturing gel electrophoretic separation of complex I from small quantities of mitochondria samples, in-gel digestion, in combination with phosphopeptide enrichment by titanium d...

Clinical bending of nickel titanium wires

Directory of Open Access Journals (Sweden)

Stephen Chain

2015-01-01

Full Text Available Since the evolution and the involvement of Nickel Titanium wires in the field of Orthodontics. The treatment plan has evolved with the use of low force Nickel Titanium wires. Because of their high springback, low stiffness, they are the key initial wires in leveling and alignment but have poor formability. Since poor formability limits its ability to create variable arch forms thus; limits the form of treatment. We have devised a method to bend the Nickel Titanium wires to help in our inventory but also customized the wire according to the treatment.

Synthesis of gels with basis of titanium tungstates as matrixes of radioactive generators; Sintesis de geles a base de titanio tungstenatos como matrices de generadores radiactivos

Energy Technology Data Exchange (ETDEWEB)

Galico C, L

2005-07-01

The heteropolyanions, compounds formed by the union of molybdates or tungstates polyanions with atoms of metals like zirconium, titanium, cerium, thorium, tin, etc., have been used as generator matrixes of {sup 99m} Tc or {sup 188} Re. Particularly they have been studied and produced successfully in our laboratory, generators of {sup 99} Mo/ {sup 99}m Tc at basis of gels zirconium molybdates and titanium molybdates. Considering that the molybdenum and tungsten, as well as the technetium and the rhenium, its belong to the same groups of transition metals, it is feasible that gels can be synthesized at basis of titanium tungstates, continuing a methodology similar to that of the gels titanium molybdates or zirconium molybdates, to produce generators {sup 188} W/ {sup 188} Re. The {sup 188} Re possess nuclear characteristics that make it attractive for therapeutic applications, since, it emits {beta}{sup -} particles of a great energy (2.12 MeV); joined to the possibility of being able to unite to different ligands (bifunctional agents) and biomolecules (antibodies or fragments of proteins), as it makes the {sup 99m} Tc, useful in radioimmunotherapy. Commercially the {sup 188} Re generators use a chromatographic column loaded with alumina where the {sup 188} Re, it is adsorbed and eluted the {sup 188} ReO{sub 4}{sup -} by means of a saline solution The alumina adsorbs around 0.2% of the {sup 188} Re, situation that forces to use {sup 188} Re of a high specific activity. The use of the gels technology, allows to work with medium or low specific activities of {sup 188} Re, opening the possibility of their production in countries whose nuclear capacity is medium or low. In particular, the synthesized gels with basis of titanium offer the possibility of being synthesized with non active material, for later on to be irradiated and directly produce the generator, since, the titanium {sup 51} Ti, unique radioisotope produced by the titanium, has a half life of 5.79 min. This

Printing of Titanium implant prototype

International Nuclear Information System (INIS)

Wiria, Florencia Edith; Shyan, John Yong Ming; Lim, Poon Nian; Wen, Francis Goh Chung; Yeo, Jin Fei; Cao, Tong

2010-01-01

Dental implant plays an important role as a conduit of force and stress to flow from the tooth to the related bone. In the load sharing between an implant and its related bone, the amount of stress carried by each of them directly related to their stiffness or modulus. Hence, it is a crucial issue for the implant to have matching mechanical properties, in particular modulus, between the implant and its related bone. Titanium is a metallic material that has good biocompatibility and corrosion resistance. Whilst the modulus of the bulk material is still higher than that of bone, it is the lowest among all other commonly used metallic implant materials, such as stainless steel or cobalt alloy. Hence it is potential to further reduce the modulus of pure Titanium by engineering its processing method to obtain porous structure. In this project, porous Titanium implant prototype is fabricated using 3-dimensional printing. This technique allows the flexibility of design customization, which is beneficial for implant fabrication as tailoring of implant size and shape helps to ensure the implant would fit nicely to the patient. The fabricated Titanium prototype had a modulus of 4.8-13.2 GPa, which is in the range of natural bone modulus. The compressive strength achieved was between 167 to 455 MPa. Subsequent cell culture study indicated that the porous Titanium prototype had good biocompatibility and is suitable for bone cell attachment and proliferation.

Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells.

Science.gov (United States)

Tada-Oikawa, Saeko; Ichihara, Gaku; Fukatsu, Hitomi; Shimanuki, Yuka; Tanaka, Natsuki; Watanabe, Eri; Suzuki, Yuka; Murakami, Masahiko; Izuoka, Kiyora; Chang, Jie; Wu, Wenting; Yamada, Yoshiji; Ichihara, Sahoko

2016-04-16

Titanium dioxide (TiO₂) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO₂ nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO₂ nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO₂ particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO₂ particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO₂ particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO₂ particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO₂ particles also increased IL-8 expression. The results indicated that anatase TiO₂ nanoparticles induced inflammatory responses compared with other TiO₂ particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

Production of titanium from ilmenite: a review

Energy Technology Data Exchange (ETDEWEB)

Kohli, R.

1981-12-01

The general principles for beneficiation of titanium ores are reviewed and the specific processes used in individual units in various countries are discussed. This is followed by a critical evaluation of various current and potential reduction methods for the production of titanium metal from the processed concentrates. Finally, the report outlines a research program for the development of a commercially viable alternative method for the production of titanium metal.

Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

KAUST Repository

Li, Hui

2018-02-01

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

KAUST Repository

Li, Hui; Sun, Ying; Yuan, Zhong-Yong; Zhu, Yun-Pei; Ma, Tianyi

2018-01-01

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

Investigation on the Effect of Sulfur and Titanium on the Microstructure of Lamellar Graphite Iron

DEFF Research Database (Denmark)

Moumeni, Elham; Stefanescu, Doru Michael; Tiedje, Niels Skat

2013-01-01

The goal of this work was to identify the inclusions in lamellar graphite cast iron in an effort to explain the nucleation of the phases of interest. Four samples of approximately the same carbon equivalent but different levels of sulfur and titanium were studied. The Ti/S ratios were from 0...... of complex Al, Ca, Mg oxide. An increased titanium level of 0.35 pct produced superfine interdendritic graphite (~10 μm) at low (0.012 wt pct) as well as at high-S contents. Ti also caused increased segregation in the microstructure of the analyzed irons and larger eutectic grains (cells). TiC did not appear...... to be a nucleation site for the primary austenite as it was found mostly at the periphery of the secondary arms of the austenite, in the last region to solidify. The effect of titanium in refining the graphite and increasing the austenite fraction can be explained through the widening of the liquidus...

On the solubility of hydrogen in the systems titanium-aluminium-hydrogen, titanium-vanadium-hydrogen and titanium-aluminium-vanadium-hydrogen in the temperature region of 800 to 1,0000C at hydrogen pressures of 0.1 to 400 mm.Hg

International Nuclear Information System (INIS)

Kauder, G.W.

1973-01-01

The hydrogen concentrations on Ti-Al, Ti-V and Ti-Al-V alloys were determined in the temperature region from 800 to 1,000 0 C and at hydrogen pressures of 0.1 to 400 mm.Hg using a gravimetric measuring process. The thus obtained results allowed the drawing of hydrogen activity slopes in the titanium rich corner of the systems titanium-hydrogen, titanium-aluminium-hydrogen, titanium-vanadium-hydrogen and such for the technical titanium alloys Ti-6Al-4V and Ti-6Al-6V. In spite of the antagonistic effects of the elements aluminium and vanadium on the stabilization of the α and β phase regions of titanium, a hydrogen-activity-increasing effect was always found in which the aluminium influence was greater than that of vanadium. Breaks occured in the hydrogen activity curves and phase boundaries, and phase regions were determined over their positions. Isothermal phase diagrams for the titanium-rich corner of the system titanium-aluminium-hydrogen at 800, 850 and 900 0 C and for the titanium-rich corner of the titanium-vanadium-hydrogen system at 900, 950 and 1,000 0 C were drawn up from the hydrogen activity curves. (orig./LH) [de

New Titanium-Based Catalysts for the Synthesis of Poly(ethylene terephthalate)

International Nuclear Information System (INIS)

Yang, Youngkeun; Yoon, Seungwoong; Hwang, Yongtaek; Song, Bogeun

2012-01-01

catalyst. Titanium metal has strong activity in polyesterification and forms stable complex with heteroatom-containing ligands (Scheme 1). These properties of titanium have been used advantageously in simple methods of syntheses and production of inexpensive metal catalyst. The high activity and selectivity of titanium-containing catalysts, their good solubility, and the absence of acidic effluent, which causes corrosion, are the reasons why these catalysts are frequently used in industry

Ball bearings comprising nickel-titanium and methods of manufacture thereof

Science.gov (United States)

DellaCorte, Christopher (Inventor); Glennon, Glenn N. (Inventor)

2012-01-01

Disclosed herein is a friction reducing nickel-titanium composition. The nickel-titanium composition includes a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38. A bearing for reducing friction comprising a nickel-titanium composition comprising a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38; where the bearing is free from voids and pinholes.

Machining of titanium alloys

CERN Document Server

2014-01-01

This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

Osseointegration of titanium, titanium alloy and zirconia dental implants: current knowledge and open questions.

Science.gov (United States)

Bosshardt, Dieter D; Chappuis, Vivianne; Buser, Daniel

2017-02-01

Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel-fibered and lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone-implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro-rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid-etching may currently be regarded as the gold standard technique to create micro-rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium-zirconium implants in both animals and humans. Surface modifications of zirconia and alumina-toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone-to-implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well-documented implant systems with micro-rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long-term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri-implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm-induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone

UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

Directory of Open Access Journals (Sweden)

Saita M

2016-01-01

Full Text Available Makiko Saita,1 Takayuki Ikeda,1,2 Masahiro Yamada,1,3 Katsuhiko Kimoto,4 Masaichi Chang-Il Lee,5 Takahiro Ogawa1 1Division of Advanced Prosthodontics, Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Yokosuka, Japan; 3Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; 4Department of Prosthodontics and Oral Rehabilitation, 5Yokosuka-Shonan Disaster Health Emergency Research Center and ESR Laboratories, Kanagawa Dental University Graduate School of Dentistry, Yokosuka, Japan Background: Although biomimetic apatite coating is a promising way to provide titanium with osteoconductivity, the efficiency and quality of deposition is often poor. Most titanium implants have microscale surface morphology, and an addition of nanoscale features while preserving the micromorphology may provide further biological benefit. Here, we examined the effect of ultraviolet (UV light treatment of titanium, or photofunctionalization, on the efficacy of biomimetic apatite deposition on titanium and its biological capability.Methods and results: Micro-roughed titanium disks were prepared by acid-etching with sulfuric acid. Micro-roughened disks with or without photofunctionalization (20-minute exposure to UV light were immersed in simulated body fluid (SBF for 1 or 5 days. Photofunctionalized titanium disks were superhydrophilic and did not form surface air bubbles when immersed in SBF, whereas non-photofunctionalized disks were hydrophobic and largely covered with air bubbles during immersion. An apatite-related signal was observed by X-ray diffraction on photofunctionalized titanium after 1 day of SBF immersion, which was equivalent to the one observed after 5 days of immersion of control titanium. Scanning electron microscopy revealed nodular apatite deposition

Scattering by multiple parallel radially stratified infinite cylinders buried in a lossy half space.

Science.gov (United States)

Lee, Siu-Chun

2013-07-01

The theoretical solution for scattering by an arbitrary configuration of closely spaced parallel infinite cylinders buried in a lossy half space is presented in this paper. The refractive index and permeability of the half space and cylinders are complex in general. Each cylinder is radially stratified with a distinct complex refractive index and permeability. The incident radiation is an arbitrarily polarized plane wave propagating in the plane normal to the axes of the cylinders. Analytic solutions are derived for the electric and magnetic fields and the Poynting vector of backscattered radiation emerging from the half space. Numerical examples are presented to illustrate the application of the scattering solution to calculate backscattering from a lossy half space containing multiple homogeneous and radially stratified cylinders at various depths and different angles of incidence.

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

Science.gov (United States)

Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

2015-12-01

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

Industrial experience with titanium

Energy Technology Data Exchange (ETDEWEB)

Ikeda, B M; Shoesmith, D W

1997-09-01

Titanium is a reference material for the construction of waste containers in the Canadian Nuclear Fuel Waste Management Program. It has been in industrial service for over 30 a, often in severe corrosion environments, but it is still considered a relatively exotic material with limited operating history. This has arisen because of the aerospace applications of this material and the misconception that the high strength-to-weight ratio dominates the choice of this material. In fact, the advantage of titanium lies in its high reliability and excellent corrosion resistance. It has a proven record in seawater heat exchanger service and a demonstrated excellent reliability even in polluted water. For many reasons it is the technically correct choice of material for marine applications. In this report we review the industrial service history of titanium, particularly in hot saline environments, and demonstrate that it is a viable waste container material, based upon this industrial service history and operating experience. (author) 83 refs., 17 tabs., 3 figs.

Industrial experience with titanium

International Nuclear Information System (INIS)

Ikeda, B.M.; Shoesmith, D.W.

1997-09-01

Titanium is a reference material for the construction of waste containers in the Canadian Nuclear Fuel Waste Management Program. It has been in industrial service for over 30 a, often in severe corrosion environments, but it is still considered a relatively exotic material with limited operating history. This has arisen because of the aerospace applications of this material and the misconception that the high strength-to-weight ratio dominates the choice of this material. In fact, the advantage of titanium lies in its high reliability and excellent corrosion resistance. It has a proven record in seawater heat exchanger service and a demonstrated excellent reliability even in polluted water. For many reasons it is the technically correct choice of material for marine applications. In this report we review the industrial service history of titanium, particularly in hot saline environments, and demonstrate that it is a viable waste container material, based upon this industrial service history and operating experience. (author)

Combining 3D human in vitro methods for a 3Rs evaluation of novel titanium surfaces in orthopaedic applications.

Science.gov (United States)

Stevenson, G; Rehman, S; Draper, E; Hernández-Nava, E; Hunt, J; Haycock, J W

2016-07-01

In this study, we report on a group of complementary human osteoblast in vitro test methods for the preclinical evaluation of 3D porous titanium surfaces. The surfaces were prepared by additive manufacturing (electron beam melting [EBM]) and plasma spraying, allowing the creation of complex lattice surface geometries. Physical properties of the surfaces were characterized by SEM and profilometry and 3D in vitro cell culture using human osteoblasts. Primary human osteoblast cells were found to elicit greater differences between titanium sample surfaces than an MG63 osteoblast-like cell line, particularly in terms of cell survival. Surface morphology was associated with higher osteoblast metabolic activity and mineralization on rougher titanium plasma spray coated surfaces than smoother surfaces. Differences in osteoblast survival and metabolic activity on titanium lattice structures were also found, despite analogous surface morphology at the cellular level. 3D confocal microscopy identified osteoblast organization within complex titanium surface geometries, adhesion, spreading, and alignment to the biomaterial strut geometries. Mineralized nodule formation throughout the lattice structures was also observed, and indicative of early markers of bone in-growth on such materials. Testing methods such as those presented are not traditionally considered by medical device manufacturers, but we suggest have value as an increasingly vital tool in efficiently translating pre-clinical studies, especially in balance with current regulatory practice, commercial demands, the 3Rs, and the relative merits of in vitro and in vivo studies. Biotechnol. Bioeng. 2016;113: 1586-1599. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ferdman, Alla

2005-05-11

The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead composite material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no

Casting of Titanium and its Alloys

OpenAIRE

R. L. Saha; K. T. Jacob

1986-01-01

Titaniuni and its alloys have many applications in aerospace, marine and other engineering industries. Titanium requires special melting techniques because of its high reactivity at elevated temperatures and needs special mould materials and methods for castings. This paper reviews the development of titanium casting technology.

Comparative in vitro biocompatibility of nickel-titanium, pure nickel, pure titanium, and stainless steel: genotoxicity and atomic absorption evaluation.

Science.gov (United States)

Assad, M; Lemieux, N; Rivard, C H; Yahia, L H

1999-01-01

The genotoxicity level of nickel-titanium (NiTi) was compared to that of its pure constituents, pure nickel (Ni) and pure titanium (Ti) powders, and also to 316L stainless steel (316L SS) as clinical reference material. In order to do so, a dynamic in vitro semiphysiological extraction was performed with all metals using agitation and ISO requirements. Peripheral blood lymphocytes were then cultured in the presence of all material extracts, and their comparative genotoxicity levels were assessed using electron microscopy-in situ end-labeling (EM-ISEL) coupled to immunogold staining. Cellular chromatin exposition to pure Ni and 316L SS demonstrated a significantly stronger gold binding than exposition to NiTi, pure Ti, or the untreated control. In parallel, graphite furnace atomic absorption spectrophotometry (AAS) was also performed on all extraction media. The release of Ni atoms took the following decreasing distribution for the different resulting semiphysiological solutions: pure Ni, 316L SS, NiTi, Ti, and controls. Ti elements were detected after elution of pure titanium only. Both pure titanium and nickel-titanium specimens obtained a relative in vitro biocompatibility. Therefore, this quantitative in vitro study provides optimistic results for the eventual use of nickel-titanium alloys as surgical implant materials.

The Molybdenum titanium Phase Diagram Evaluated from Ab initio Calculations

Science.gov (United States)

2016-10-07

solid solution, therefore occurs at lower temperatures and is more complex than previously anticipated. 1. Introduction The demand for permanent...and relatively low elastic moduli [1, 2, 3, 4, 5, 6, 7, 8, 9]. Titanium alloys with low Young’s moduli inhibit the stress shielding effect and thus...Instituut Voor Kern-en Stralingsfysica, K. U. Leuven, Belgium), 2002, ISBN 90- 807215-1-4 (http://www,wien2k.at/reg_user/ textbooks ). 36 J. P. Desclaux

Peculiarities in power type comparison results for half-linear dynamic equations

Czech Academy of Sciences Publication Activity Database

Řehák, Pavel

2012-01-01

Roč. 42, č. 6 (2012), s. 1995-2013 ISSN 0035-7596 R&D Projects: GA AV ČR KJB100190701 Institutional support: RVO:67985840 Keywords : half-linear dynamic equation * time scale * comparison theorem Subject RIV: BA - General Mathematics Impact factor: 0.389, year: 2012 http://projecteuclid.org/euclid.rmjm/1361800616

Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

Science.gov (United States)

Kothari, Kunal B.

Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron

Preparation of titanium diboride powders from titanium alkoxide and ...

Indian Academy of Sciences (India)

Administrator

Department of Materials and Manufacturing Process, Malek Ashtar University of Technology, Tehran. 15875-1744, Iran ... Titanium diboride is a hard refractory material with a high melting point ... (λ = 1⋅540598 Å) radiation. Morphology of the ...

Adherence of extracellular matrix components to modified surfaces of titanium alloys

International Nuclear Information System (INIS)

Stelzer, C; Uhlmann, E; Meinke, M; Lademann, J; Hansen, U

2009-01-01

The adherence of biological materials on metal surfaces is of special importance in biology and medicine. The underlying interactions between surface and biological materials (e.g. extracellular matrix components or cells) are responsible for the application as a medical device. Numerous products are made of pure titanium and titanium alloys. This paper shows the influence of a laser production technology on machined surfaces of TiAl 6 V 4 and the resulting adherence of biological material on the basis of the surface characterisation. In this study, different machined TiAl 6 V 4 surfaces were used for coatings with extracellular matrix components. For this process, different coating with collagen I monomers and a complex mixture of extracellular matrix proteins derived from the dermal-epidermal basement membrane zone were analysed. The efficiency of the coating was analysed by different methods and the results are presented in this paper

Lunar-derived titanium alloys for hydrogen storage

Science.gov (United States)

Love, S.; Hertzberg, A.; Woodcock, G.

1992-01-01

Hydrogen gas, which plays an important role in many projected lunar power systems and industrial processes, can be stored in metallic titanium and in certain titanium alloys as an interstitial hydride compound. Storing and retrieving hydrogen with titanium-iron alloy requires substantially less energy investment than storage by liquefaction. Metal hydride storage systems can be designed to operate at a wide range of temperatures and pressures. A few such systems have been developed for terrestrial applications. A drawback of metal hydride storage for lunar applications is the system's large mass per mole of hydrogen stored, which rules out transporting it from earth. The transportation problem can be solved by using native lunar materials, which are rich in titanium and iron.

Mineral resource of the month: titanium

Science.gov (United States)

Gambogi, Joseph

2011-01-01

Titanium is hip - at least when it comes to airplanes and jewelry. Known for its high strength-to weight ratio and its resistance to corrosion, titanium and its alloys can also be found in everything from knee replacements to eyeglass frames to baseball bats to fighter planes.

Titanium metal obtention by fused salts electrolysis

International Nuclear Information System (INIS)

Perillo, P.M.; Ares, Osvaldo; Botbol, Jose.

1989-01-01

Potassium fluorotitanate dissolved in fused sodium chloride or potassium chloride may be electrolyzed under an inert gas atmosphere. Solid electrolysis products are formed on the cathode which contains titanium metal, sodium chloride, lower fluorotitanates and small quantities of alkali metal fluorotitanate. The extraction of titanium from the electrolysis products may be carried out by aqueous leaching (removal of chloride salts of alkali metals and a certain amount of fluorotitanates). Titanium metal obtained is relatively pure. (Author)

Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

Science.gov (United States)

Dathar, Gopi Krishna Phani

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory

Genesis of apocarbonatitic titanium metasomatites of the Petyayan-vara rare-earth occurrence (Vuoriyarvi, the Kola Region

Directory of Open Access Journals (Sweden)

Kozlov E. N.

2018-03-01

Full Text Available The objects of the study are apocarbonatitic titanium metasomatites ("titanium carbonatites" associated with the rare earth carbonatites of the Petyayan-Vara area of the Vuoriyarvi complex (the Kola region. In this paper, the following mechanism for the formation of these rocks has been substantiated based on the agreed results of mineralogical and geochemical studies. Prior to the onset of carbonatite genesis, a fluorine-enriched fluid phase originated in the lower horizons of the complex passed along the deep-permeating fracture system of several hundred meters length up to the level of the modern erosion surface. It transported Al, Fe2+, Mg, Ti, P into the pyroxenites and Si, Ca and Na out of them, as a result of which the pyroxenites were transformed into giant-grained phlogopite rocks – glimmerites. The most probable source of this fluid is alkaline aluminosilicate magma. Then carbonate melts intruded along the same fractures. In the course of carbonatite genesis, F-fluid caused a local migration of K, Al, Si, Fe, P, Ti, Nb, Ta, Zr, Hf and HREE out of glimmerites into igneous dolomite carbonatites, which led to the formation of apocarbonatitic titanium metasomatites. They represent several paragenetic associations superimposed on each other, the mineral composition and the formation sequence of which correspond to the metasomatic column zones directly observed within the contact "carbonatite – altered pyroxenite". The separation of HFSE and REE is controlled by the same metasomatic column: Ti, Nb and Ta were accumulated in titanium carbonatites, i. e. in associations of the frontal and intermediate zones, and Zr, Hf and HREE – in apatitized fields corresponding to the rear zone of the column. Accordingly, the fractionation of these elements occurred due to the "fluid – rock" interaction. Subsequently, the same long-lived fractures served as a channel for REE-Sr-Ba-S fluids, but the recrystallization caused by K

Development of a Single Locus Sequence Typing (SLST) Scheme for Typing Bacterial Species Directly from Complex Communities.

Science.gov (United States)

Scholz, Christian F P; Jensen, Anders

2017-01-01

The protocol describes a computational method to develop a Single Locus Sequence Typing (SLST) scheme for typing bacterial species. The resulting scheme can be used to type bacterial isolates as well as bacterial species directly from complex communities using next-generation sequencing technologies.

Influence of titanium implant surface characteristics on bone regeneration in dehiscence-type defects: an experimental study in dogs.

Science.gov (United States)

Schwarz, Frank; Sager, Martin; Kadelka, Ines; Ferrari, Daniel; Becker, Jürgen

2010-05-01

The aim of the present study was to compare bone regeneration in dehiscence-type defects at titanium implants with chemically modified sandblasted/acid-etched (modSLA) or dual acid-etched surfaces with a calcium phosphate nanometre particle modification (DCD/CaP). Buccal dehiscence-type defects were surgically created following implant site preparation in both the upper and the lower jaws of 12 fox hounds. Both types of implants were randomly allocated in a split-mouth design and left to heal in a submerged position for 2 and 8 weeks. Dissected blocks were processed for histomorphometrical analysis [e.g. new bone height (NBH), percentage of bone-to-implant contact (BIC), area of new bone fill (BF), and area of mineralized tissue (MT) within BF]. At 2 and 8 weeks, both groups revealed comparable mean BF (2.3+/-0.6 to 2.5+/-0.6 mm(2)versus 2.0+/-0.6 to 1.4+/-0.5 mm(2)) and MT (31.1+/-14.3-83.2+/-8.2%versus 38.9+/-15.9-84.4+/-6.3%) values. However, modSLA implants revealed significantly higher mean NBH (2.4+/-0.8 to 3.6+/-0.3 mm versus 0.9+/-0.8 to 1.8+/-1.4 mm) and BIC (53.3+/-11.3-79.5+/-6.6%versus 19.3+/-16.4-47.2+/-30.7%) values than DCD/CaP implants. ModSLA implants may have a higher potential to support osseointegration in dehiscence-type defects than DCD/CaP implants.

Recent Developments in Half-Metallic Magnetism

NARCIS (Netherlands)

Groot, R.A. de; Buschow, K.H.J.

1986-01-01

The compound PtMnSb is a half-metallic ferromagnet and its unusual band structure is intimately connected with the high Magneto Optical Kerr Effect (MOKE). In this paper it will be discussed how various types of substitutions can modify this band structure and lead to possible enhancement of the

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

OpenAIRE

Wen-Tao Yu; Jing Li; Cheng-Bin Shi; Qin-Tian Zhu

2016-01-01

The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix duri...

Attachment and growth behaviour of human gingival fibroblasts on titanium and zirconia ceramic surfaces

International Nuclear Information System (INIS)

Pae, Ahran; Kim, Hyeong-Seob; Woo, Yi-Hyung; Lee, Heesu; Kwon, Yong-Dae

2009-01-01

The attachment, growth behaviour and the genetic effect of human gingival fibroblasts (HGF) cultured on titanium and different zirconia surfaces were investigated. HGF cells were cultured on (1) titanium discs with a machined surface, (2) yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) with a smooth surface and (3) Y-TZP with 100 μm grooves. The cell proliferation activity was evaluated through a MTT assay at 24 h and 48 h, and the cell morphology was examined by SEM. The mRNA expression of integrin-β1, type I and III collagen, laminin and fibronectin in HGF were evaluated by RT-PCR after 24 h. From the MTT assay, the mean optical density values for the titanium and grooved zirconia surfaces after 48 h of HGF adhesion were greater than the values obtained for the smooth zirconia surfaces. SEM images showed that more cells were attached to the grooves, and the cells appeared to follow the direction of the grooves. The results of RT-PCR suggest that all groups showed comparable fibroblast-specific gene expression. A zirconia ceramic surface with grooves showed biological responses that were comparable to those obtained with HGF on a titanium surface.

Biocompatibility of Advanced Manufactured Titanium Implants—A Review

Science.gov (United States)

Sidambe, Alfred T.

2014-01-01

Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy. PMID:28788296

Biocompatibility of Advanced Manufactured Titanium Implants—A Review

Directory of Open Access Journals (Sweden)

Alfred T. Sidambe

2014-12-01

Full Text Available Titanium (Ti and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy.

Biocompatibility of Advanced Manufactured Titanium Implants-A Review.

Science.gov (United States)

Sidambe, Alfred T

2014-12-19

Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy.

Difference in surface reactions between titanium and zirconium in Hanks' solution to elucidate mechanism of calcium phosphate formation on titanium using XPS and cathodic polarization

International Nuclear Information System (INIS)

Tsutsumi, Y.; Nishimura, D.; Doi, H.; Nomura, N.; Hanawa, T.

2009-01-01

Titanium and zirconium were immersed in Hanks' solution with and without calcium and phosphate ions, and the surfaces were characterized with X-ray photoelectron spectroscopy (XPS) to determine the mechanism of calcium phosphate formation on titanium in simulated body fluids and in a living body. In addition, they were cathodically polarized in the above solutions. XPS characterization and cathodic polarization revealed differences in the surface properties in the ability of calcium phosphate formation between titanium and zirconium. The surface oxide film on titanium is not completely oxidized and is relatively reactive; that on zirconium is more passive and protective than that on titanium. Neither calcium nor phosphate stably exists alone on titanium, and calcium phosphate is naturally formed on it; calcium phosphate formed on titanium is stable and protective. On the other hand, calcium is never incorporated on zirconium, while zirconium phosphate, which is easily formed on zirconium, is highly stable and protective. Our study presents new information regarding the surface property of titanium and demonstrates that the characteristics of titanium and zirconium may be applied to various medical devices and new surface modification techniques.

Appcelerator Titanium business application development cookbook

CERN Document Server

Bahrenberg, Benjamin

2013-01-01

Presented in easy to follow, step by step recipes, this guide is designed to lead you through the most important aspects of application design.Titanium developers who already have a basic knowledge of working with Appcelerator Titanium but want to further develop their knowledge for use with business applications

Re-configurable digital receiver for optically envelope detected half cycle BPSK and MSK radio-on-fiber signals

DEFF Research Database (Denmark)

Guerrero Gonzalez, Neil; Prince, Kamau; Zibar, Darko

2011-01-01

We present the first known integration of a digital receiver into optically envelope detection radio-on-fiber systems. We also present a re-configurable scheme for two different types of optically envelope detected wireless signals while keeping the complexity of used optical components low. Our...... novel digital receiver consists of a digital signal processing unit integrating functions such as filtering, peak-powers detection, symbol synchronization and signal demodulation for optically envelope detected half-cycle binary phase-shift-keying and minimum-shift-keying signals. Furthermore, radio......-frequency signal down-conversion is not required in our proposed approach; simplifying evens more the optical receiver front-end. We experimentally demonstrate error-free optical transmission (bit-error rate corresponding to 10−3 related to FEC-compatible levels) for both 416.6 Mbit/s half-cycle binary phase...

Effect of liquid properties on laser ablation of aluminum and titanium alloys

Energy Technology Data Exchange (ETDEWEB)

Ouyang, Peixuan, E-mail: oypx12@mails.tsinghua.edu.cn [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Li, Peijie [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Leksina, E.G.; Michurin, S.V. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119992 (Russian Federation); He, Liangju [School of Aerospace, Tsinghua University, Beijing 100084 (China)

2016-01-01

Graphical abstract: - Highlights: • Porous surfaces are formed in Al alloy after wet ablation due to phase explosion. • A higher ablation rate is produced in glycerin than that in water and isopropanol. • Effect of liquid properties on mass-removal mechanisms was discussed. • Phase explosion and plasma-induced pressure contribute greatly to mass removal. • Density, heat conductivity and shock impendence of liquid affect ablation rates. - Abstract: In order to study the effect of liquid properties on laser ablation in liquids, aluminum 5A06 and titanium TB5 targets were irradiated by single-pulse infrared laser in isopropanol, distilled water, glycerin and as a comparison, in air, respectively. Craters induced by laser ablation were characterized using scanning electron and white-light interferometric microscopies. The results show that for liquid-mediated ablation, craters with porous surface structures were formed in aluminum target through phase explosion, while no micro-cavities were formed in titanium target owing to high critical temperature of titanium. In addition, ablation rates of aluminum and titanium targets vary with types of ambient media in accordance with such sequence: air < isopropanol < water < glycerin. Further, the influence of liquid properties on material-removal mechanisms for laser ablation in liquid is discussed. It is concluded that the density, thermal conductivity and acoustical impedance of liquid play a dominant role in laser ablation efficiency.

Characterization and properties of shock and corrosion resistant of titanium based coatings

International Nuclear Information System (INIS)

Motoiu, P.; Rosso, M.

2001-01-01

Thermal spraying technologies are an effective way to ensure surface protection against destructive effects of wear, corrosion and oxidizing phenomena. These technologies can be applied in majority of industrial sectors in order to improve properties of new parts or for reconditioning worn out parts technology. Ideally, it would be comfortable to have a material able to resist to all type of wear, but the work condition intricacy combined with economic reason have lead to the development of a big number of powder materials that are used in thermal spraying technologies. The titanium powders are suitable for coating layers which have a good behavior in 'metal on metal friction', toughness, shock and corrosion resistance. In particular, titanium layers obtained by plasma spraying are used in different aerospace and non aerospace applications due to the combination of low density, very good mechanical properties and high corrosion resistance. The accomplishment of new titanium thermal layers is effectively used in order to increase the lifetime of different engine parts securing the thermal protection in use, resistance to high corrosion and oxidizing phenomena. This paper deals about the mechanical properties of Ti based coatings applied by plasma spray process on steel substrates, the obtained results show the possibility to apply titanium coatings where special and high performance materials are needed. (author)

Oxygen depth profiling in Kr+-implanted polycrystalline alpha titanium by means of 16O(α,α)16O resonance scattering

International Nuclear Information System (INIS)

Nsengiyumva, S.; Riviere, J.P.; Raji, A.T.; Comrie, C.M.; Britton, D.T.; Haerting, M.

2011-01-01

The 16 O(α,α) 16 O resonance scattering was applied to study the effects of ion implantation on the oxygen distribution in the near surface region of polycrystalline titanium implanted with 180 keV krypton ions at fluences, ranging between 1 x 10 14 and 5 x 10 15 Kr + /cm 2 . Two sample sets were chosen: as-received polycrystalline titanium discs rolled and annealed in half-hard condition which had a thick oxygen layer and similar samples in which this surface layer was removed by polishing. An increase of the mean oxygen concentration observed in both unpolished and polished samples at low fluence suggests a knock-on implantation of surface oxygen atoms. At high fluence, an overall decrease in the mean oxygen concentration and mean oxygen depth suggests an out-diffusion of near-surface oxygen atoms.

Enhanced osteoblast adhesion to drug-coated anodized nanotubular titanium surfaces

Directory of Open Access Journals (Sweden)

George E Aninwene II

2008-06-01

Full Text Available George E Aninwene II1, Chang Yao2, Thomas J Webster21Department of Biochemical Engineering, University of Maryland, Baltimore, MD; 2Division of Engineering, Brown University, Providence, RI, USAAbstract: Current orthopedic implants have functional lifetimes of only 10–15 years due to a variety of reasons including infection, extensive inflammation, and overall poor osseointegration (or a lack of prolonged bonding of the implant to juxtaposed bone. To improve properties of titanium for orthopedic applications, this study anodized and subsequently coated titanium with drugs known to reduce infection (penicillin/streptomycin and inflammation (dexamethasone using simple physical adsorption and the deposition of such drugs from simulated body fluid (SBF. Results showed improved drug elution from anodized nanotubular titanium when drugs were coated in the presence of SBF for up to 3 days. For the first time, results also showed that the simple physical adsorption of both penicillin/streptomycin and dexamethasone on anodized nanotubular titanium improved osteoblast numbers after 2 days of culture compared to uncoated unanodized titanium. In addition, results showed that depositing such drugs in SBF on anodized titanium was a more efficient method to promote osteoblast numbers compared to physical adsorption for up to 2 days of culture. In addition, osteoblast numbers increased on anodized titanium coated with drugs in SBF for up to 2 days of culture compared to unanodized titanium. In summary, compared to unanodized titanium, this preliminary study provided unexpected evidence of greater osteoblast numbers on anodized titanium coated with either penicillin/streptomycin or dexamethasone using simple physical adsorption or when coated with SBF; results which suggest the need for further research on anodized titanium orthopedic implants possessing drug-eluting nanotubes.Keywords: anodization, titanium, adhesion, simulated body fluid, nanotubes

Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

KAUST Repository

Ali, Haider; Yang, Xinbo; Weber, Klaus; Schoenfeld, Winston V.; Davis, Kristopher O.

2017-01-01

In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21

Custom-made laser-welded titanium implant prosthetic abutment.

Science.gov (United States)

Iglesia-Puig, Miguel A

2005-10-01

A technique to create an individually modified implant prosthetic abutment is described. An overcasting is waxed onto a machined titanium abutment, cast in titanium, and joined to it with laser welding. With the proposed technique, a custom-made titanium implant prosthetic abutment is created with adequate volume and contour of metal to support a screw-retained, metal-ceramic implant-supported crown.

Titanium exposure and yellow nail syndrome

Directory of Open Access Journals (Sweden)

Ali Ataya

2015-01-01

Full Text Available Yellow nail syndrome is a rare disease of unclear etiology. We describe a patient who develops yellow nail syndrome, with primary nail and sinus manifestations, shortly after amalgam dental implants. A study of the patient's nail shedding showed elevated nail titanium levels. The patient had her dental implants removed and had complete resolution of her sinus symptoms with no change in her nail findings. Since the patient's nail findings did not resolve we do not believe titanium exposure is a cause of her yellow nail syndrome but perhaps a possible relationship exists between titanium exposure and yellow nail syndrome that requires further studies.

Complexity and Intensionality in a Type-1 Framework for Computable Analysis

DEFF Research Database (Denmark)

Lambov, Branimir Zdravkov

2005-01-01

This paper describes a type-1 framework for computable analysis designed to facilitate efficient implementations and discusses properties that have not been well studied before for type-1 approaches: the introduction of complexity measures for type-1 representations of real functions, and ways...

Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

Science.gov (United States)

Pereira, J. Michael; Revilock, Duane M.; Ruggeri, Charles R.; Emmerling, William C.; Altobelli, Donald J.

2012-01-01

An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade.

Load Deflection Characteristics of Nickel Titanium Initial Archwires

Directory of Open Access Journals (Sweden)

Hossein Aghili

2016-05-01

Full Text Available Objectives: The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs.Materials and Methods: This study tested three wire designs namely copper nickel titanium (CNT, nickel titanium (NiTi, and multi-strand NiTi (MSNT archwires engaged in passive self-ligating (PSL brackets, active self-ligating (ASL brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length were recorded. Two-way ANOVA and Tukey’s test were used at P <0.05 level of significance.Results: Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force.Conclusion: With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.

Thermoexpanded graphite modification by titanium dioxide

International Nuclear Information System (INIS)

Semko, L.S.; Gorbik, P.P.; Chujko, O.O.; Kruchek, Ya.Yi.; Dzyubenko, L.S.; Orans'ka, O.Yi.

2006-01-01

A method of the synthesis of thermoexpanded graphite (TEG) powders coated by titanium dioxide is developed. The conversion of n-buthylorthotitanate into TiO 2 on the TEG surface is investigated. The optimal parameters of the synthesis and the structure of titanium dioxide clusters on the TEG surface are determined

Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices

Science.gov (United States)

Freund, Roland

1989-01-01

We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.

Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells

Science.gov (United States)

Tada-Oikawa, Saeko; Ichihara, Gaku; Fukatsu, Hitomi; Shimanuki, Yuka; Tanaka, Natsuki; Watanabe, Eri; Suzuki, Yuka; Murakami, Masahiko; Izuoka, Kiyora; Chang, Jie; Wu, Wenting; Yamada, Yoshiji; Ichihara, Sahoko

2016-01-01

Titanium dioxide (TiO2) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO2 particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles. PMID:27092499

Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells

Directory of Open Access Journals (Sweden)

Saeko Tada-Oikawa

2016-04-01

Full Text Available Titanium dioxide (TiO2 nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2 cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm and rutile (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL of anatase (100 nm, rutile (50 nm, and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm TiO2 particles increased interleukin (IL-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

Comparison of galvanic corrosion potential of metal injection molded brackets to that of conventional metal brackets with nickel-titanium and copper nickel-titanium archwire combinations.

Science.gov (United States)

Varma, D Praveen Kumar; Chidambaram, S; Reddy, K Baburam; Vijay, M; Ravindranath, D; Prasad, M Rajendra

2013-05-01

The aim of the study is to investigate the galvanic corrosion potential of metal injection molding (MIM) brackets to that of conventional brackets under similar in vitro conditions with nickel-titanium and copper nickel-titanium archwires. Twenty-five maxillary premolar MIM stainless steel brackets and 25 conventional stainless steel brackets and archwires, 0.16 inch, each 10 mm length, 25 nickeltitanium wires, 25 copper nickel-titanium wires were used. They were divided into four groups which had five samples each. Combination of MIM bracket with copper nickel-titanium wire, MIM bracket with nickel-titanium wire and conventional stainless steel brackets with copper nickel-titanium wire and conventional stainless steel brackets with nickel-titanium wires which later were suspended in 350 ml of 1 M lactic acid solution media. Galvanic corrosion potential of four groups were analyzed under similar in vitro conditions. Precorrosion and postcorrosion elemental composition of MIM and conventional stainless steel bracket by scanning electron microscope (SEM) with energy dispersive spectroscope (EDS) was done. MIM bracket showed decreased corrosion susceptibility than conventional bracket with copper nickeltitanium wire. Both MIM and conventional bracket showed similar corrosion resistance potential in association with nickel-titanium archwires. It seems that both brackets are more compatible with copper nickel-titanium archwires regarding the decrease in the consequences of galvanic reaction. The EDS analysis showed that the MIM brackets with copper nickel-titanium wires released less metal ions than conventional bracket with copper nickeltitanium wires. MIM brackets showed decreased corrosion susceptibility, copper nickel-titanium archwires are compatible with both the brackets than nickel-titanium archwires. Clinically MIM and conventional brackets behaved more or less similarly in terms of corrosion resistance. In order to decrease the corrosion potential of MIM