Functional modularity in lake-dwelling characin fishes of Mexico

PubMed Central

Bautista, Amando; Herder, Fabian; Doadrio, Ignacio

2017-01-01

Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi, which are differentiated by their trophic habits. Two different datasets were analyzed: (1) skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi) to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2) a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi). Skull shape showed significant differences among species and sex (P < 0.001), where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body), being significant only for A. caballeroi. PMID:28951817

Functional modularity in lake-dwelling characin fishes of Mexico.

PubMed

Ornelas-García, Claudia Patricia; Bautista, Amando; Herder, Fabian; Doadrio, Ignacio

2017-01-01

Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi , which are differentiated by their trophic habits. Two different datasets were analyzed: (1) skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi ) to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2) a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi ). Skull shape showed significant differences among species and sex ( P  < 0.001), where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body), being significant only for A. caballeroi .

The modular endoprosthesis for mandibular body replacement. Part 2: finite element analysis of endoprosthesis reconstruction of the mandible.

PubMed

Wong, Raymond C W; Tideman, Henk; Merkx, Matthias A W; Jansen, John; Goh, Suk Ming

2012-12-01

Problems with loosening of the modules for the modular endoprosthesis were encountered in animal studies for mandibular body replacement. We performed a finite element analysis to look at the stress distribution and areas of stress concentration in a human sized mandible. Variations were made to the stem and defect length to look at how the forces changed. The hypothesis was: (1) reconstruction with a modular endoprosthesis did not lead to areas of stress concentration beyond the material strength of cortical bone and titanium alloy; (2) changes in dimensions of the endoprosthesis did not cause a corresponding linear increase to the stresses. The endoprosthesis was modelled to create a male, female part with stems and a connection screw (Case I). The stem length was halved (Case II) and defect length doubled (Case III). Geometric data of a human sized mandible were obtained, a continuity defect created digitally at the right molar area and the models combined. Boundary conditions were set and the model loaded to get a bite force of 300 N at the incisor region. An intact mandible was used as a control. The right side of the reconstructed mandible became less rigid and flexed more. The highest stresses were within the endoprosthesis at two areas of stress concentration: (1) shear stress at the superior surface of the stems close to the junction of the stem and the module body; (2) compressive stresses at the bottom bevel of the dove-tailed connection. The stress distribution for Case I and II did not differ much except for the magnitude which was slightly higher for Case II. There was a tendency for outward bending at the module connection for Case III which potentially might cause loosening of the module connection. Displacements of the mandible were less than 1 mm throughout. The endoprosthesis with its present dimensions would be expected to perform adequately at a bite force of 300 N. An increase in defect length caused a tendency for bending at the stem and the module connection. With a decrease in stem length, there were little differences except a slight increase in magnitude. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Conceptual design and thermal analysis of a modular cryostat for one single coil of a 10 MW offshore superconducting wind turbine

NASA Astrophysics Data System (ADS)

Sun, Jiuce; Sanz, Santiago; Neumann, Holger

2015-12-01

Superconducting generators show the potential to reduce the head mass of large offshore wind turbines. A 10 MW offshore superconducting wind turbine has been investigated in the SUPRAPOWER project. The superconducting coils based on MgB2 tapes are supposed to work at cryogenic temperature of 20 K. In this paper, a novel modular rotating cryostat was presented for one single coil of the superconducting wind turbine. The modular concept and cryogen-free cooling method were proposed to fulfil the requirements of handling, maintenance, reliability of long term and offshore operations. Two stage Gifford-McMahon cryocoolers were used to provide cooling source. Supporting rods made of titanium alloy were selected as support structures of the cryostat in aim of reducing the heat load. The thermal performance in the modular cryostat was carefully investigated. The heat load applied to the cryocooler second stage was 2.17 W@20 K per coil. The corresponding temperature difference along the superconducting coil was only around 1 K.

La Recherche Aerospatiale, Bimonthly Bulletin, no. 1982-6, 211/November-Decemter 1982

NASA Astrophysics Data System (ADS)

Sevestre, C.

1983-04-01

A modular method for centrifugal compressor performance prediction is presented. Cyclic hardening of stainless steel under complex loading is described. Fatigue failure microinitiation, micropropagation and damage is considered. The stability of a tilting rotor aircraft model is studied. The thermal stability of titanium alloys is investigated. A compensator for thermal effects on quartz oscillators is described.

Infected total knee arthroplasty treated with arthrodesis using a modular nail.

PubMed

Waldman, B J; Mont, M A; Payman, K R; Freiberg, A A; Windsor, R E; Sculco, T P; Hungerford, D S

1999-10-01

Failed treatment of infected total knee replacement presents few attractive surgical options. Knee arthrodesis is challenging surgically and can be complicated by nonunion, malunion, or recurrent infection. Recently, a modular titanium intramedullary nail has been used in an attempt to reduce the incidence of nonunion and the rate of complications. In the present study, a review of the results of knee arthrodesis after infected total knee arthroplasty in 21 patients at three large academic institutions was performed. All patients were followed up for a mean of 2.4 years (range, 2-7.5 years). The mean age of the patients was 64 years. The mean number of previous operations was four (range, 2-9 operations). A solid arthrodesis was achieved without additional surgical treatment in 20 of 21 patients (95%). The mean time to fusion was 6.3 months. The one patient who suffered a nonunion achieved fusion after a subsequent bone grafting procedure. Based on the present study, intramedullary arthrodesis with a coupled titanium nail, is a reliable, effective method of achieving fusion after infection of a total knee arthroplasty. This procedure resulted in a high rate of fusion and a lower rate of complications when compared with traditional methods of arthrodesis.

Biological response on a titanium implant-grade surface functionalized with modular peptides☆

PubMed Central

Yazici, H.; Fong, H.; Wilson, B.; Oren, E.E.; Amos, F.A.; Zhang, H.; Evans, J.S.; Snead, M.L.; Sarikaya, M.; Tamerler, C.

2015-01-01

Titanium (Ti) and its alloys are among the most successful implantable materials for dental and orthopedic applications. The combination of excellent mechanical and corrosion resistance properties makes them highly desirable as endosseous implants that can withstand a demanding biomechanical environment. Yet, the success of the implant depends on its osteointegration, which is modulated by the biological reactions occurring at the interface of the implant. A recent development for improving biological responses on the Ti-implant surface has been the realization that bifunctional peptides can impart material binding specificity not only because of their molecular recognition of the inorganic material surface, but also through their self-assembly and ease of biological conjugation properties. To assess peptide-based functionalization on bioactivity, the present authors generated a set of peptides for implant-grade Ti, using cell surface display methods. Out of 60 unique peptides selected by this method, two of the strongest titanium binding peptides, TiBP1 and TiBP2, were further characterized for molecular structure and adsorption properties. These two peptides demonstrated unique, but similar molecular conformations different from that of a weak binder peptide, TiBP60. Adsorption measurements on a Ti surface revealed that their disassociation constants were 15-fold less than TiBP60. Their flexible and modular use in biological surface functionalization were demonstrated by conjugating them with an integrin recognizing peptide motif, RGDS. The functionalization of the Ti surface by the selected peptides significantly enhanced the bioactivity of osteoblast and fibroblast cells on implant-grade materials. PMID:23159566

Effect of Glucose Concentration on Electrochemical Corrosion Behavior of Pure Titanium TA2 in Hanks’ Simulated Body Fluid

PubMed Central

Liu, Shuyue; Wang, Bing; Zhang, Peirong

2016-01-01

Titanium and its alloys have been widely used as implant materials due to their excellent mechanical property and biocompatibility. In the present study, the effect of glucose concentration on corrosion behavior of pure titanium TA2 in Hanks’ simulated body fluid is investigated by the electrochemical impedance spectrum (EIS) and potentiodynamic polarization methods. The range of glucose concentrations investigated in this research includes 5 mmol/L (limosis for healthy people), 7 mmol/L (after diet for healthy people), 10 mmol/L (limosis for hyperglycemia patient), and 12 mmol/L (after diet for hyperglycemia patient), as well as, 15 mmol/L and 20 mmol/L, which represent different body fluid environments. The results indicate that the pure titanium TA2 demonstrates the best corrosion resistance when the glucose concentration is less than 10 mmol/L, which shows that the pure titanium TA2 as implant material can play an effective role in the body fluids with normal and slight high glucose concentrations. Comparatively, the corrosion for the pure titanium implant is more probable when the glucose concentration is over 10 mmol/L due to the premature penetration through passive film on the material surface. Corrosion defects of pitting and crevice exist on the corroded surface, and the depth of corrosion is limited to three microns with a low corrosion rate. The oxidation film on the surface of pure titanium TA2 has a protective effect on the corrosion behavior of the implant inner material. The corrosion behavior of pure titanium TA2 will happen easily once the passive film has been penetrated through. The corrosion rate for TA2 implant will accelerate quickly and a pure titanium implant cannot be used. PMID:28773993

Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode

NASA Astrophysics Data System (ADS)

Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

2014-09-01

Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the `modular' body mapping sportswear was designed and subsequently assessed on a `Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode.

PubMed

Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

2014-09-01

Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the 'modular' body mapping sportswear was designed and subsequently assessed on a 'Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

Bone remodelling around HA-coated acetabular cups

PubMed Central

Nielsen, P. T.; Søballe, K.

2006-01-01

This study was designed to investigate bone remodelling around the cup in cementless THA. Previous studies indicate an advantage of better sealing of the bone-prosthesis interface by HA/TCP coating of implants, inhibiting polyethylene-induced osteolysis. One hundred patients gave informed consent to participate in a controlled randomized study between porous coated Trilogy versus Trilogy Calcicoat (HA/TCP coated). The cup was inserted in press-fit fixation. The femoral component was a cementless porous coated titanium alloy stem (Bi-Metric), with a modular 28-mm CrCo head. The Harris Hip Score (HHS) and bone mineral density (BMD) determined by DEXA scanning were used to study the effect. Measurements revealed no difference between the two groups after 3 years either in the clinical outcome or in terms of periprosthetic bone density. Patients with a body mass index above normal regained more bone mineral than patients with normal weight. This finding supports the assumption that load is beneficial to bone remodelling. PMID:16761153

The application of SMA spring actuators to a lightweight modular compliant surface bioinspired robot

NASA Astrophysics Data System (ADS)

Stone, David L.; Cranney, John; Liang, Robert; Taya, Minoru

2004-07-01

The DARPA Sponsored Compliant Surface Robotics (CSR) program pursues development of a high mobility, lightweight, modular, morph-able robot for military forces in the field and for other industrial uses. The USTLAB and University of Washington Center for Intelligent Materials and Systems (CIMS) effort builds on USTLAB proof of concept feasibility studies and demonstration of a 4, 6, or 8 wheeled modular vehicle with articulated leg-wheel assemblies. A collaborative effort between USTLAB and UW-CIMS explored the application of Shape Memory Alloy Nickel Titanium Alloy springs to a leg extension actuator capable of actuating with 4.5 Newton force over a 50 mm stroke. At the completion of Phase II, we have completed mechanical and electronics engineering design and achieved conventional actuation which currently enable active articulation, enabling autonomous reconfiguration for a wide variety of terrains, including upside down operations (in case of flip over), have developed a leg extension actuator demonstration model, and we have positioned our team to pursue a small vehicle with leg extension actuators in follow on work. The CSR vehicle's modular spider-like configuration facilitates adaptation to many uses and compliance over rugged terrain. The developmental process, actuator and vehicle characteristics will be discussed.

Modular Cognitive-Behavioral Therapy for Body Dysmorphic Disorder

ERIC Educational Resources Information Center

Wilhelm, Sabine; Phillips, Katharine A.; Fama, Jeanne M.; Greenberg, Jennifer L.; Steketee, Gail

2011-01-01

This study pilot tested a newly developed modular cognitive-behavioral therapy (CBT) treatment manual for body dysmorphic disorder (BDD). We tested feasibility, acceptability, and treatment outcome in a sample of 12 adults with primary BDD. Treatment was delivered in weekly individual sessions over 18 or 22 weeks. Standardized clinician ratings…

Modular Organization of Dynamic Camouflage Body Patterning in Cuttlefish

DTIC Science & Technology

2014-11-28

Final 3. DATES COVERED (From - To) 28 Feb 13 – 19 Sept 14 4. TITLE AND SUBTITLE Modular organization of dynamic camouflage body...responsive areas are positively correlated with increasing voltages and depths of the electrode in the medulla of the optic lobe, and (2) the island- like...aim of using the dynamically changing visual background to study the spatiotemporal expression of body patterns was not successful, we discovered

Hardening Effect Analysis by Modular Upper Bound and Finite Element Methods in Indentation of Aluminum, Steel, Titanium and Superalloys

PubMed Central

Bermudo, Carolina; Sevilla, Lorenzo; Martín, Francisco; Trujillo, Francisco Javier

2017-01-01

The application of incremental processes in the manufacturing industry is having a great development in recent years. The first stage of an Incremental Forming Process can be defined as an indentation. Because of this, the indentation process is starting to be widely studied, not only as a hardening test but also as a forming process. Thus, in this work, an analysis of the indentation process under the new Modular Upper Bound perspective has been performed. The modular implementation has several advantages, including the possibility of the introduction of different parameters to extend the study, such as the friction effect, the temperature or the hardening effect studied in this paper. The main objective of the present work is to analyze the three hardening models developed depending on the material characteristics. In order to support the validation of the hardening models, finite element analyses of diverse materials under an indentation are carried out. Results obtained from the Modular Upper Bound are in concordance with the results obtained from the numerical analyses. In addition, the numerical and analytical methods are in concordance with the results previously obtained in the experimental indentation of annealed aluminum A92030. Due to the introduction of the hardening factor, the new modular distribution is a suitable option for the analysis of indentation process. PMID:28772914

Enhanced Densification and Hardness of Titanium Bodies Sintered by Advanced Hydrogen Sintering Process

NASA Astrophysics Data System (ADS)

Oh, Jung-Min; Koo, Ja-Geon; Lim, Jae-Won

2018-05-01

A new sintering technique for enhancing a densification and hardness of sintered titanium body by supplying hydrogen was developed (Hydrogen Sintering Process, HSP). The HSP was developed by only injecting hydrogen into an argon atmosphere during the core time. As a result, sound titanium sintered bodies with high density and hardness were obtained by the HSP. In addition, a pore size and number of the HSP specimens were smaller than those of the argon atmosphere specimen. It was found that the injecting hydrogen into the argon atmosphere by HSP can prevent the formation of oxide layers, resulting in enhanced densification and hardness.

Shape optimization of the modular press body

NASA Astrophysics Data System (ADS)

Pabiszczak, Stanisław

2016-12-01

A paper contains an optimization algorithm of cross-sectional dimensions of a modular press body for the minimum mass criterion. Parameters of the wall thickness and the angle of their inclination relative to the base of section are assumed as the decision variables. The overall dimensions are treated as a constant. The optimal values of parameters were calculated using numerical method of the tool Solver in the program Microsoft Excel. The results of the optimization procedure helped reduce body weight by 27% while maintaining the required rigidity of the body.

A comparison of preload values in gold and titanium dental implant retaining screws.

PubMed

Doolabh, R; Dullabh, H D; Sykes, L M

2014-08-01

This in vitro investigation compared the effect of using either gold or titanium retaining screws on preload in the dental implant- abutment complex. Inadequate preload can result in screw loosening, whilst fracture may occur if preload is excessive. These are the most commonly reported complications in implant-retained prostheses, and result in unscheduled, costly and time-consuming visits for the patient and the clinician. This study investigated changes in preload generation after repeated torque applications to gold and titanium screws. The test set-up consisted of an implant body, a cylindrical transmucosa abutment, and the test samples of gold and of titanium retaining screws. The implant bodies were anchored using a load cell, and the transmucosal abutments were attached using either gold or titanium retaining screws. A torque gauge was used to apply torque of 20Ncm, 32Ncm, and 40Ncm to the retaining screws. The preloads generated in each screw type were compared at each torque setting, and after repeated tightening episodes. In addition, the effect of applying torque beyond the manufacturers' recommendations was also examined. Gold retaining screws were found to achieve consistently higher preload values than titanium retaining screws. Preload values were not significantly different from the first to the tenth torque cycle. Titanium screws showed more consistent preload values, albeit lower than those of the gold screws. However due to possible galling of the internal thread of the implant body by titanium screws, gold screws remain the retaining screw of choice. Based on the findings of this study, gold retaining screws generate better preload than titanium. Torque beyond the manufacturers' recommendations resulted in a more stable implant complex. However, further investigations, with torque applications repeated until screw breakage, are needed to advise on ideal maintenance protocols.

[Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

PubMed

Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

2015-12-01

To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

Modular design attitude control system

NASA Technical Reports Server (NTRS)

Chichester, F. D.

1984-01-01

A sequence of single axismodels and a series of reduced state linear observers of minimum order are used to reconstruct inaccessible variables pertaining to the modular attitude control of a rigid body flexible suspension model of a flexible spacecraft. The single axis models consist of two, three, four, and five rigid bodies, each interconnected by a flexible shaft passing through the mass centers of the bodies. Modal damping is added to each model. Reduced state linear observers are developed for synthesizing the inaccessible modal state variables for each modal model.

Modular to Monoblock: Difficulties of Detaching the M(2)a-Magnum(TM) Head Are Common in Metal-on-metal Revisions.

PubMed

Mäntymäki, Heikki; Mäkelä, Keijo T; Vahlberg, Tero; Hirviniemi, Joni; Niinimäki, Tuukka

2016-09-01

Modern hip implants typically feature modular heads, which allow for easy exchange and removal from the femoral stem at the time of revision. However, owing to fretting, corrosion, or cold welding, the modular head may be difficult or impossible to separate from the underlying trunnion, especially if the implant has titanium interfaces between the head and the stem. We have repeatedly encountered difficulty removing the titanium sleeve adapter in the M(2)a-Magnum(TM) implant. Although the manufacturer warns about this complication and cases with these difficulties have been reported to the United States FDA, we believed this topic is important to study, because the frequency of difficulties in head removal is unknown and the complications related to this event have not been characterized. We asked: (1) Do revisions of M(2)a-Magnum(TM) implants differ from those of M(2)a-38(TM) implants in terms of ease of removal of the femoral head? (2) In cases where difficulty with M(2)a-Magnum(TM) head removal occurred, was the operative time, bleeding, risk of periprosthetic fracture, or joint infection increased compared with cases where the M(2)a-Magnum(TM) head was removed without difficulties? Between 2004 and 2014, we revised 296 THAs with metal-on-metal implants that involved M(2)a-Magnum(TM) (123) or M(2)a-38(TM) heads (88); of those, 84 were planned to include a femoral stem revision and insufficient data were available for three operations, so they were excluded from this analysis, leaving 124 THAs in the current retrospective study (70 THAs with M(2)a-Magnum(TM) and 54 THAs with M(2)a-38(TM) heads).The method of modular head removal, any difficulties removing the femoral head from the trunnion, operation time, and complications were recorded based on chart review. All the observed problems of detaching the head or taper adapter were among M(2)a-Magnum(TM) heads; there were no problems detaching the head in revisions of the M(2)a-38(TM) implant. In 29% (20 of 70) of revisions of the M(2)a-Magnum(TM) implant, the modular head could not be detached by knocking it with a punch and a mallet. Seventeen percent (12 of 70) of hips needed an unplanned stem revision owing to difficulties with head removal. In revisions of the M(2)a-Magnum(TM) implant that experienced head-removal problems, the median operative time was longer (144 minutes; range, 75-274 minutes) and bleeding was greater (725 mL; range, 300-2200 mL) compared with revisions of the M(2)a-Magnum(TM) implant without head removal problems (77 minutes, range, 33-197 minutes, p < 0.001; 475 mL, range, 50-1500 mL, p = 0.004). With the numbers available, we did not see differences in terms of the proportion of patients experiencing major complications (periprosthetic fracture or postoperative infections) between the groups (difficult versus easy; 25% [five of 20] versus 8% [four of 50]; odds ratio, 3.8 [95% CI, 0.9-16.2], p = 0.067). The titanium-titanium taper junction can be very difficult to separate during revision THAs, and if not anticipated, this problem can result in larger and more complicated revision procedures in patients who have the M(2)a-Magnum(TM) implant. Although the global use of metal-on-metal implants in THAs has decreased dramatically during the last several years, many thousands remain in service and therefore still might require revision. It is crucial to be prepared with special tools, including a femoral head extraction tool and diamond saw. The patient has to be informed of the possibility of a more extensive operation than preoperatively planned. Level III, therapeutic study.

Identification And Characterization Of The Solids Found In Extraction Contactor SEP-401 In June 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fondeur, F. F.; Fink, S. D.

2012-12-10

The Modular Caustic-Side Solvent Extraction Unit (MCU) recently conducted an outage that included maintenance on the centrifugal contactors. Operations personnel observed solids or deposits in two contactors and attempted to collect samples for analyses by Savannah River National Laboratory (SRNL). The residues found in Extraction Contactor SEP-401 are a mixture of amorphous silica, aluminosilicate, titanium, and debris from low alloy steel. The solids contain low concentrations of plutonium and strontium. These isotopes are associated with the titanium that came from the monosodium titanate (MST) added in the Actinide Removal Process (ARP) most likely as leached Ti from the MST thatmore » precipitated subsequently in MCU. An attempt was also made to obtain samples from the contents of Wash Contactor SEP-702. However, sampling provide ineffective.« less

Clinical outcomes of Kyocera Modular Limb Salvage system after resection of bone sarcoma of the distal part of the femur: the Japanese Musculoskeletal Oncology Group study.

PubMed

Nakamura, Tomoki; Matsumine, Akihiko; Uchida, Atsumasa; Kawai, Akira; Nishida, Yoshihiro; Kunisada, Toshiyuki; Araki, Nobuhito; Sugiura, Hideshi; Tomita, Masato; Yokouchi, Masahiro; Ueda, Takafumi; Sudo, Akihiro

2014-04-01

The Japanese Musculoskeletal Oncology Group have developed an original prosthesis called the Kyocera Modular Limb Salvage system (KMLS system). This prosthesis has a semi-rotating hinge joint and is particularly designed for people with an Asian body type. The metallic parts of the prosthesis are made entirely of titanium alloy. The purpose of this study is to evaluate the clinical outcomes of treatment using this system following tumour resection of primary bone sarcoma of the distal femur. Between 2002 and 2010, 82 patients with primary bone sarcomas of the distal femur were treated. Seventeen patients underwent stem cementation, while 65 patients were treated with cementless prostheses. The mean follow-up period after surgery was 61 months. Complications were observed in 28 of the 82 patients. Forty-one complications occurred in these 28 patients. Thirteen prostheses (16%) required revision surgery due to complications, including five cases of stem breakage, three deep infections, three cases of aseptic loosening, one case of displacement of the shaft cap and one case of breakage of the tibial tray. The five-year overall prosthetic survival rate was 80.0%. Four of the 82 patients underwent subsequent amputation due to local recurrence. The five-year limb salvage rate was 94.5%. The mean function score according to the scoring system of the Musculoskeletal Tumour Society was 21.8 points (72.5%). Although further follow-up is required to determine the performance, this prosthesis is considered to be satisfactory for reconstruction of the distal femur after resection of bone sarcoma.

Characterization of materials eliciting foreign body reaction in stapled human gastrointestinal anastomoses.

PubMed

Lim, C B B; Goldin, R D; Darzi, A; Hanna, G B

2008-08-01

Staples are made of titanium, which elicits minimal tissue reaction. The authors have encountered foreign body reaction associated with stapled human gastrointestinal anastomoses, although the literature has no reports of this. The aim of this study was to identify the refractile foreign materials causing this reaction. Histological sections were taken from 14 gastrointestinal specimens from patients with a history of a stapled anastomosis within the specimen excised. These were reviewed by light and polarization microscopy. Scanning electron microscopy and energy dispersive X-ray analysis were carried out on these sections, staples and stapler cartridges used for gastrointestinal surgery. Foreign bodies rich in fluorine were found in three patients, and those rich in carbon in 12. Other elements identified included oxygen, calcium, sodium, potassium, magnesium, aluminium and silicon. One specimen was found to contain titanium with no surrounding foreign body reaction. Stapler cartridges contained carbon, oxygen, fluorine, calcium, sodium, potassium, magnesium, aluminium, silicon and traces of titanium. Staples were composed of pure titanium with some fibrous material on the surface containing elements found in stapler cartridges. The presence of foreign body reaction was confirmed in stapled human gastrointestinal anastomoses. The source of refractile materials eliciting this reaction was the stapler cartridges. (c) 2008 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

Effect of hot water and heat treatment on the apatite-forming ability of titania films formed on titanium metal via anodic oxidation in acetic acid solutions.

PubMed

Cui, Xinyu; Kim, Hyun-Min; Kawashita, Masakazu; Wang, Longbao; Xiong, Tianying; Kokubo, Tadashi; Nakamura, Takashi

2008-04-01

Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile. The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.

JPRS Report, Science & Technology, Japan

DTIC Science & Technology

1991-01-31

final test. Keywords: Spherical Pressure Hull, Titanium Alloy , Three-Dimensional Machining, Electron Beam Welding . 1. Introduction In bodies like... processed (the heat treatment involving high-temperature heating and rapid quenching in order to obtain finer grains of the titanium alloy ) and...given m Table 3. The test results were all satisfactory. Forged material of titanium alloy , manufactured by forging, beta processing , and billet

[The bonding characteristic of titanium and RG experiment porcelain].

PubMed

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 < 0.01). The fracture force for the Ni-Cr alloy/VMK99 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.

The effect of SF6 addition in a Cl2/Ar inductively coupled plasma for deep titanium etching

NASA Astrophysics Data System (ADS)

Laudrel, E.; Tillocher, T.; Meric, Y.; Lefaucheux, P.; Boutaud, B.; Dussart, R.

2018-05-01

Titanium is a material of interest for the biomedical field and more particularly for body implantable devices. Titanium deep etching by plasma was carried out in an inductively coupled plasma with a chlorine-based chemistry for the fabrication of titanium-based microdevices. Bulk titanium etch rate was first studied in Cl2/Ar plasma mixture versus the source power and the self-bias voltage. The plasma was characterized by Langmuir probe and by optical emission spectroscopy. The addition of SF6 in the plasma mixture was investigated. Titanium etch rate was optimized and reached a value of 2.4 µm · min-1. The nickel hard mask selectivity was also enhanced. The etched titanium surface roughness was reduced significantly.

Stabilizing the body centered cubic crystal in titanium alloys by a nano-scale concentration modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, H. L.; Shah, S. A. A.; Hao, Y. L.

It is well-known that the body centered cubic (bcc) crystal in titanium alloys reaches its stability limit as the electron-to-atom (e/a) ratio of the alloy drops down to ~4.24. This critical value, however, is much higher than that of a multifunctional bcc type alloy (e/a = 4.15). Here we demonstrate that a nano-scale concentration modulation created by spinodal decomposition is what stabilizes the bcc crystal of the alloy. Aided by such a nano-scale concentration heterogeneity, unexpected properties from its chemically homogeneous counterpart are obtained. This provides a new strategy to design functional titanium alloys by tuning the spinodal decomposition.

Space-by-Time Modular Decomposition Effectively Describes Whole-Body Muscle Activity During Upright Reaching in Various Directions

PubMed Central

Hilt, Pauline M.; Delis, Ioannis; Pozzo, Thierry; Berret, Bastien

2018-01-01

The modular control hypothesis suggests that motor commands are built from precoded modules whose specific combined recruitment can allow the performance of virtually any motor task. Despite considerable experimental support, this hypothesis remains tentative as classical findings of reduced dimensionality in muscle activity may also result from other constraints (biomechanical couplings, data averaging or low dimensionality of motor tasks). Here we assessed the effectiveness of modularity in describing muscle activity in a comprehensive experiment comprising 72 distinct point-to-point whole-body movements during which the activity of 30 muscles was recorded. To identify invariant modules of a temporal and spatial nature, we used a space-by-time decomposition of muscle activity that has been shown to encompass classical modularity models. To examine the decompositions, we focused not only on the amount of variance they explained but also on whether the task performed on each trial could be decoded from the single-trial activations of modules. For the sake of comparison, we confronted these scores to the scores obtained from alternative non-modular descriptions of the muscle data. We found that the space-by-time decomposition was effective in terms of data approximation and task discrimination at comparable reduction of dimensionality. These findings show that few spatial and temporal modules give a compact yet approximate representation of muscle patterns carrying nearly all task-relevant information for a variety of whole-body reaching movements. PMID:29666576

Brain connectome modularity in weight-restored anorexia nervosa and body dysmorphic disorder

PubMed Central

Zhang, A; Leow, A; Zhan, L; GadElkarim, J; Moody, T; Khalsa, S; Strober, M; Feusner, JD

2017-01-01

Background Anorexia nervosa (AN) and body dysmorphic disorder (BDD) frequently co-occur, and have several overlapping phenomenological features. Little is known about their shared neurobiology. Aims To compare modular organization of brain structural connectivity. Methods We acquired diffusion-weighted magnetic resonance imaging data on unmedicated individuals with BDD (n=29), weight-restored AN (n=24), and healthy controls (HC) (n=31). We constructed connectivity matrices using whole-brain white matter tractography, and compared modular structures across groups. Results AN showed abnormal modularity involving frontal, basal ganglia, and posterior cingulate nodes. There was a trend in BDD for similar abnormalities, but no significant differences compared with AN. In AN, poor insight correlated with longer path length in right caudal anterior cingulate and right posterior cingulate. Conclusions Abnormal network organization patterns in AN, partially shared with BDD, may have implications for understanding integration between reward and habit/ritual formation, as well as conflict monitoring/error detection. PMID:27429183

Modular neuron-based body estimation: maintaining consistency over different limbs, modalities, and frames of reference

PubMed Central

Ehrenfeld, Stephan; Herbort, Oliver; Butz, Martin V.

2013-01-01

This paper addresses the question of how the brain maintains a probabilistic body state estimate over time from a modeling perspective. The neural Modular Modality Frame (nMMF) model simulates such a body state estimation process by continuously integrating redundant, multimodal body state information sources. The body state estimate itself is distributed over separate, but bidirectionally interacting modules. nMMF compares the incoming sensory and present body state information across the interacting modules and fuses the information sources accordingly. At the same time, nMMF enforces body state estimation consistency across the modules. nMMF is able to detect conflicting sensory information and to consequently decrease the influence of implausible sensor sources on the fly. In contrast to the previously published Modular Modality Frame (MMF) model, nMMF offers a biologically plausible neural implementation based on distributed, probabilistic population codes. Besides its neural plausibility, the neural encoding has the advantage of enabling (a) additional probabilistic information flow across the separate body state estimation modules and (b) the representation of arbitrary probability distributions of a body state. The results show that the neural estimates can detect and decrease the impact of false sensory information, can propagate conflicting information across modules, and can improve overall estimation accuracy due to additional module interactions. Even bodily illusions, such as the rubber hand illusion, can be simulated with nMMF. We conclude with an outlook on the potential of modeling human data and of invoking goal-directed behavioral control. PMID:24191151

Does impaction of titanium-coated interbody fusion cages into the disc space cause wear debris or delamination?

PubMed

Kienle, Annette; Graf, Nicolas; Wilke, Hans-Joachim

2016-02-01

A large number of interbody fusion cages are made of polyetheretherketone (PEEK). To improve bone on-growth, some are coated with a thin layer of titanium. This coating may fail when subjected to shear loading. The purpose of this testing was to investigate whether impaction of titanium-coated PEEK cages into the disc space can result in wear or delamination of the coating, and whether titanium cages with subtractive surface etching (no coating) are less susceptible to such failure. A biomechanical study was carried out to simulate the impaction process in clinical practice and to evaluate if wear or delamination may result from impaction. Two groups of posterior lumbar interbody fusion cages with a similar geometry were tested: n=6 titanium-coated PEEK and n=6 surface-etched titanium cages. The cages were impacted into the space in between two vertebral body substitutes (polyurethane foam blocks). The two vertebral body substitutes were fixed in a device, through which a standardized axial preload of 390 N was applied. The anterior tip of the cage was positioned at the posterior border of the space between the two vertebral body substitutes. The cages were then inserted using a drop weight with a mass representative of a surgical hammer. The drop weight impacted the insertion instrument at a maximum speed of about 2.6 m/s, which is in the range of the impaction speed in vivo. This was repeated until the cages were fully inserted. The wear particles were captured and analyzed according to the pertinent standards. The surface-etched titanium cages did not show any signs of wear debris or surface damage. In contrast, the titanium-coated PEEK cages resulted in detached wear particles of different sizes (1-191 µm). Over 50% of these particles had a size <10 µm. In median, on 26% of the implants' teeth, the coating was abraded. Full delamination was not observed. In contrast to the surface-etched implants, the titanium-coated PEEK implants lost some coating material. This was visible to the naked eye. More than half of all particles were of a size range that allows phagocytosis. This study shows that titanium-coated implants are susceptible to impaction-related wear debris. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Modular optical topometric sensor for 3D acquisition of human body surfaces and long-term monitoring of variations.

PubMed

Bischoff, Guido; Böröcz, Zoltan; Proll, Christian; Kleinheinz, Johannes; von Bally, Gert; Dirksen, Dieter

2007-08-01

Optical topometric 3D sensors such as laser scanners and fringe projection systems allow detailed digital acquisition of human body surfaces. For many medical applications, however, not only the current shape is important, but also its changes, e.g., in the course of surgical treatment. In such cases, time delays of several months between subsequent measurements frequently occur. A modular 3D coordinate measuring system based on the fringe projection technique is presented that allows 3D coordinate acquisition including calibrated color information, as well as the detection and visualization of deviations between subsequent measurements. In addition, parameters describing the symmetry of body structures are determined. The quantitative results of the analysis may be used as a basis for objective documentation of surgical therapy. The system is designed in a modular way, and thus, depending on the object of investigation, two or three cameras with different capabilities in terms of resolution and color reproduction can be utilized to optimize the set-up.

Malagasy cichlids differentially limit impacts of body shape evolution on oral jaw functional morphology.

PubMed

Martinez, Christopher M; Sparks, John S

2017-09-01

Patterns of trait covariation, such as integration and modularity, are vital factors that influence the evolution of vertebrate body plans. In functional systems, decoupling of morphological modules buffers functional change in one trait by reducing correlated variation with another. However, for complex morphologies with many-to-one mapping of form to function (MTOM), resistance to functional change may also be achieved by constraining morphological variation within a functionally stable region of morphospace. For this research, we used geometric morphometrics to evaluate the evolution of body shape and its relationship with jaw functional morphology in two independent radiations of endemic Malagasy cichlid (Teleostei: Cichlidae). Our results suggested that the two subfamilies used different strategies to mitigate impacts of body shape variation on a metric of jaw function, maxillary kinematic transmission (MKT): (1) modularity between cranial and postcranial morphologies, and (2) integration of body and jaw evolution, with jaw morphologies varying in a manner that limits change in MKT. This research shows that, unlike modularity, MTOM allows traits to retain strong evolutionary covariation while still reducing impacts on functionality. These results suggest that MTOM, and its influence on the evolution of correlated traits, is likely much more widespread than is currently understood. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Titanium sealing glasses and seals formed therefrom

DOEpatents

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

1997-01-01

Alkaline-earth lanthanoborate sealing-glass compositions containing CaO, La.sub.2 O.sub.3, B.sub.2 O.sub.3, TiO.sub.2 and Al.sub.2 O.sub.3 in various combinations of mole-% are provided. These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys that have a high aqueous durability for component or device applications requiring exposure to moisture, water or body fluids. Particular applications of the titanium sealing-glass compositions include forming glass-to-metal seals for lithium batteries and implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Modular femoral component for conversion of previous hip surgery in total hip arthroplasty.

PubMed

Goldstein, Wayne M; Branson, Jill J

2005-09-01

The conversion of previous hip surgery to total hip arthroplasty creates a durable construct that is anatomically accurate. Most femoral components with either cemented or cementless design have a fixed tapered proximal shape. The proximal femoral anatomy is changed due to previous hip surgery for fixation of an intertrochanteric hip fracture, proximal femoral osteotomy, or a fibular allograft for avascular necrosis. The modular S-ROM (DePuy Orthopaedics Inc., Warsaw, Ind) hip stem accommodates these issues and independently prepares the proximal and distal portion of the femur. In preparation and implantation, the S-ROM hip stem creates less hoop stresses on potentially fragile stress risers from screws and thin bone. The S-ROM hip stem also prepares a previously distorted anatomy by milling through cortical bone that can occlude the femoral medullar canals and recreate proper femoral anteversion and reduces the risk of intraoperative or postoperative periprosthetic fracture due to the flexible titanium-slotted stem. The S-ROM femoral stem is recommended for challenging total hip reconstructions.

Titanium sealing glasses and seals formed therefrom

DOEpatents

Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

1997-12-02

Alkaline-earth lanthanoborate sealing-glass compositions containing CaO, La{sub 2}O{sub 3}, B{sub 2}O{sub 3}, TiO{sub 2} and Al{sub 2}O{sub 3} in various combinations of mole-% are provided. These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys that have a high aqueous durability for component or device applications requiring exposure to moisture, water or body fluids. Particular applications of the titanium sealing-glass compositions include forming glass-to-metal seals for lithium batteries and implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 2 figs.

Automatic Assembly of Combined Checkingfixture for Auto-Body Components Based Onfixture Elements Libraries

NASA Astrophysics Data System (ADS)

Jiang, Jingtao; Sui, Rendong; Shi, Yan; Li, Furong; Hu, Caiqi

In this paper 3-D models of combined fixture elements are designed, classified by their functions, and saved in computer as supporting elements library, jointing elements library, basic elements library, localization elements library, clamping elements library, and adjusting elements library etc. Then automatic assembly of 3-D combined checking fixture for auto-body part is presented based on modularization theory. And in virtual auto-body assembly space, Locating constraint mapping technique and assembly rule-based reasoning technique are used to calculate the position of modular elements according to localization points and clamp points of auto-body part. Auto-body part model is transformed from itself coordinate system space to virtual assembly space by homogeneous transformation matrix. Automatic assembly of different functional fixture elements and auto-body part is implemented with API function based on the second development of UG. It is proven in practice that the method in this paper is feasible and high efficiency.

Will New Metal Heads Restore Mechanical Integrity of Corroded Trunnions?

PubMed

Derasari, Aditya; Gold, Jonathan E; Ismaily, Sabir; Noble, Philip C; Incavo, Stephen J

2017-04-01

Metal wear and corrosion from modular junctions in total hip arthroplasty can lead to further unwanted surgery. Trunnion tribocorrosion is recognized as an important contributor to failure. This study was performed to determine if new metal heads restore mechanical integrity of the original modular junction after impaction on corroded trunnions, and assess which variables affect stability of the new interface created at revision total hip arthroplasty. Twenty-two trunnions, cobalt-chromium (CoCr) and titanium alloy (TiAIV), (CoCr, n = 12; TiAIV, n = 10) and new metal heads were used, 10 trunnions in pristine condition and 12 with corrosion damage. Test states were performed using an MTS Machine and included the following: 1, Assembly; 2, Disassembly; 3, Assembly; 4, Toggling; and 5, Disassembly. During loading, three-dimensional motion of the head-trunnion junction was measured using a custom jig. There were no statistical differences in the tested mechanical properties between corroded and pristine trunnions implanted with a new metal femoral head. Average micromotion of the head versus trunnion interface was greatest at the start of loading, stabilizing after approximately 50 loading cycles at an average of 30.6 ± 3.2 μm. Corrosion at the trunnion does not disrupt mechanical integrity of the junction when a CoCr head is replaced with a CoCr trunnion. However, increased interface motion of a new metal head on a corroded titanium trunnion requires additional study. The evaluation of ball head size on mechanical integrity of trunnions would also be a potential subject of future investigation, as increasing the ball head size at the time of revision is not uncommon in revisions today. Copyright © 2016 Elsevier Inc. All rights reserved.

Arthrodesis of the knee with a modular titanium intramedullary nail.

PubMed

Arroyo, J S; Garvin, K L; Neff, J R

1997-01-01

We retrospectively studied the results of arthrodesis of the knee with a modular titanium intramedullary nail that couples at the knee. The study group consisted of thirteen patients who had a malignant tumor around the knee, five who had failure of a total knee arthroplasty, and three who had a locally destructive benign tumor about the knee. All of the patients were followed for a minimum of two years. Through a single incision at the knee, one nail was inserted retrograde into the femur and the other, antegrade into the tibia; the two nails were joined at the level of the knee by a conical couple and were secured with locking screws. The diameters of the nails were different, to accommodate the dissimilar sizes of the tibial and femoral intramedullary canals. A solid osseous fusion was achieved in nineteen (90 per cent) of the twenty-one patients (sixteen who had had resection of a tumor and three who had had a failed arthroplasty), at an average of 8.4 months (range, three to nineteen months) after the operation. One patient had a delayed union, but fusion was achieved after additional bone-grafting. Of the sixteen patients who were available for clinical and radiographic evaluation at the time of the study, fifteen were satisfied with the over-all outcome and thirteen had either less pain or the same amount of pain as they had had preoperatively. There were no mechanical failures of the implant and no recurrences of tumor. Complications occurred in eight (38 per cent) of the twenty-one patients: three patients had a stress fracture, three had a peroneal nerve palsy (one of which was transient), one had a superficial wound infection, and one had reflex sympathetic dystrophy.

Arthrodesis in septic knees using a long intramedullary nail: 17 consecutive cases.

PubMed

Leroux, B; Aparicio, G; Fontanin, N; Ohl, X; Madi, K; Dehoux, E; Diallo, S

2013-06-01

Intramedullary nailing using long or modular nails is the most reliable mean of achieving femorotibial fusion. Here, we report the operative, clinical, functional, and radiological outcomes of 17 long intramedullary nail arthodeses in patients with infection. Clinical and functional outcomes after long intramedullary nailing are at least as good as those obtained using other implants. We retrospectively reevaluated 17 patients after unilateral two-stage knee arthrodesis with a long titanium intramedullary nail and autologous bone grafting. We evaluated satisfaction, leg length discrepancy, and function (Lequesne and WOMAC indices). Radiographs were obtained to assess fusion, time to fusion, and femorotibial angles. No cases of material failure were recorded. One or more complications occurred in seven patients. Mean limb shortening was 27.6mm. Of the 17 patients, 15 were satisfied with the procedure. The mean Lequesne index was 10.5/24 and the mean overall WOMAC score was 26/88. Fusion was achieved in 16 patients, with a mean time to fusion of 5 months. Mean femorotibial angles were 178.6° of varus and 1.9° of flexion. This simple and rapid surgical technique provides functional outcomes similar to those obtained using modular nails. The fusion rate is high. Nail extraction is simple and causes minimal damage, in contrast to modular nails. Increased attention to misalignment is needed. Level IV, retrospective study. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Spark plasma sintering synthesis of porous nanocrystalline titanium alloys for biomedical applications.

PubMed

Nicula, R; Lüthen, F; Stir, M; Nebe, B; Burkel, E

2007-11-01

The reason for the extended use of titanium and its alloys as implant biomaterials stems from their lower elastic modulus, their superior biocompatibility and improved corrosion resistance compared to the more conventional stainless steel and cobalt-based alloys [Niinomi, M., Hattori, T., Niwa, S., 2004. Material characteristics and biocompatibility of low rigidity titanium alloys for biomedical applications. In: Jaszemski, M.J., Trantolo, D.J., Lewandrowski, K.U., Hasirci, V., Altobelli, D.E., Wise, D.L. (Eds.), Biomaterials in Orthopedics. Marcel Dekker Inc., New York, pp. 41-62]. Nanostructured titanium-based biomaterials with tailored porosity are important for cell-adhesion, viability, differentiation and growth. Newer technologies like foaming or low-density core processing were recently used for the surface modification of titanium alloy implant bodies to stimulate bone in-growth and improve osseointegration and cell-adhesion, which in turn play a key role in the acceptance of the implants. We here report preliminary results concerning the synthesis of mesoporous titanium alloy bodies by spark plasma sintering. Nanocrystalline cp Ti, Ti-6Al-4V, Ti-Al-V-Cr and Ti-Mn-V-Cr-Al alloy powders were prepared by high-energy wet-milling and sintered to either full-density (cp Ti, Ti-Al-V) or uniform porous (Ti-Al-V-Cr, Ti-Mn-V-Cr-Al) bulk specimens by field-assisted spark plasma sintering (FAST/SPS). Cellular interactions with the porous titanium alloy surfaces were tested with osteoblast-like human MG-63 cells. Cell morphology was investigated by scanning electron microscopy (SEM). The SEM analysis results were correlated with the alloy chemistry and the topographic features of the surface, namely porosity and roughness.

UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

PubMed Central

Saita, Makiko; Ikeda, Takayuki; Yamada, Masahiro; Kimoto, Katsuhiko; Lee, Masaichi Chang-Il; Ogawa, Takahiro

2016-01-01

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 in the valleys and at the inclines of micro-roughened structures without affecting the existing micro-configuration. Micro-roughened titanium and apatite-deposited titanium surfaces had similar roughness values. The attachment, spreading, settling, proliferation, and alkaline phosphate activity of bone marrow-derived osteoblasts were promoted on apatite-coated titanium with photofunctionalization. Conclusion UV-photofunctionalization of titanium enabled faster deposition of nanoscale biomimetic apatite, resulting in the improved biological capability compared to the similarly prepared apatite-deposited titanium without photofunctionalization. Photofunctionalization-assisted biomimetic apatite deposition may be a novel method to effectively enhance micro-roughened titanium surfaces without altering their microscale morphology. PMID:26834469

Assessment of a press-fit proximal femoral modular reconstruction implant (PFMR®) at 14.5 years. A 48-case series with a disturbing rate of implant fracture.

PubMed

Dumoulin, Q; Sabau, S; Goetzmann, T; Jacquot, A; Sirveaux, F; Mole, D; Roche, O

2018-05-01

The PFMR ® proximal femoral modular reconstruction implant (Protek, Sulzer Orthopedics, Switzerland) is a straight modular stem in sanded titanium with press-fit anchorage, intended to achieve spontaneous bone reconstruction following Wagner's principle. The aim of the present study was to analyze long-term clinical and radiological outcome. A single-center retrospective study included 48 PFMR stems implanted in 47 patients between 1998 and 2002. Results in this series were previously reported at 7 years' follow-up. Clinical assessment used PMA and Harris scores. Radiologic assessment focused on stem stability and osseointegration, and bone stock following Le Béguec. Twenty-three patients were seen at a mean 14.5 years' follow-up (13 deceased, 11 lost to follow-up), including 1 with bilateral implants, i.e., 24 stems. PMA and Harris scores, stem stability and osseointegration and bone stock were stable with respect to the 7-year findings. Radiology found 7 stem fractures in the Morse taper, i.e., in 29% of implants. Two of these cases required femoral implant replacement; 5 were asymptomatic. Long-term outcome for PFMR stems was clinically and radiologically satisfactory for the 16 patients free of mechanical complications. The Morse taper fracture rate was high, and higher than reported elsewhere. The usual risk factors for implant fracture were not found in the present series. The modular design of the press-fit revision implant is its weak point; monoblock implants should be used in patients with good life-expectancy. IV (retrospective study). Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Knee arthodesis using a modular customized intramedullary nail.

PubMed

Letartre, R; Combes, A; Autissier, G; Bonnevialle, N; Gougeon, F

2009-11-01

Arthrodesis of the knee, particularly in infectious situations, can be achieved using either an external fixator or an intramedullary device. The objective of this study is to report the clinical, functional, and radiographic outcomes of a continuous series of 19 cases of knee arthrodesis using a customized modular intramedullary nailing system. The modular intramedullary nail offers a satisfactory functional result while maintaining limb length, in spite of a nonunion risk, since acting like a true endoprosthesis. In our retrospective series of 19 patients, the main source of patients were infected total knee replacements. The nail was customized from assembling a dual surface-sanded titanium component (femoral and tibial). The Lequesne Algofunctional score and the WOMAC score were recorded, as well as the length discrepancy between the lower extremities. Arthrodesis consolidation and the nail's fit in the shaft were verified on anterior-posterior (AP) and lateral radiographs. Five complications were observed: one anterior cortical break, one excessive tibial rotation, two cases of delayed union, and one nail revision due to residual nail instability. The postoperative Lequesne Algofunctional score was 13/24 and the WOMAC score 57/100. The nonunion rate was 32%. From a functional point of view, the patients who did not achieve complete union and those who did had similar scores. The subjective results were not as good in patients who did not achieve final consolidation. Modular intramedullary nailing simplifies the technique, shortens the procedure, and reduces the amount of blood loss at surgery. Our nonunion rate was high, although the functional result did not seem compromised by such nonunion. The risk of long-term implant failure was not studied and requires longer follow-up studies. Level IV therapeutic study. 2009 Published by Elsevier Masson SAS.

[Follow-up examinations after removal of titanium plates coated with anodic titanium oxide ceramic].

PubMed

Velich, Norbert; Németh, Zsolt; Barabás, József; Szabó, György

2002-04-01

Transformation of the titanium metal surface with titanium oxides produced in various ways belongs among the most up-to-date procedures. The authors as pioneers in this field (e.g. Nobel Biocare TiUnite surface), have been utilizing for more than 15 years dental root implants and fixing elements (for mandibular osteosynthesis) coated with titanium oxide ceramics, produced by anodic oxidation and thermal treatment. The aim of this work was to assess the extent to which a titanium oxide ceramic coating influences the fate of plates applied for osteosynthesis within the human body. During a 5-year period (1995-1999), 108 of 1396 titanium oxide ceramic plates had to be removed for various reasons: loosening of the plate [47], osteomyelitis [25], a palpable swelling and tenderness [21] at the request of the patient for psychological reasons (13) or breaking of the plate [2]. When these 108 plates were removed, it was not possible to detect metallosis in even a single case; nor was there any tissue damage that could be attributed to the surface of the plates, whereas the literature data indicate that such damage is relatively frequent in the environment of traditional titanium fixing elements. The present investigation confirms the favourable properties of the titanium oxide ceramic surface.

Preparation of bioactive titania films on titanium metal via anodic oxidation.

PubMed

Cui, X; Kim, H-M; Kawashita, M; Wang, L; Xiong, T; Kokubo, T; Nakamura, T

2009-01-01

To research the crystal structure and surface morphology of anodic films on titanium metal in different electrolytes under various electrochemical conditions and investigate the effect of the crystal structure of the oxide films on apatite-forming ability in simulated body fluid (SBF). Titanium oxide films were prepared using an anodic oxidation method on the surface of titanium metal in four different electrolytes: sulfuric acid, acetic acid, phosphoric acid and sodium sulfate solutions with different voltages for 1 min at room temperature. Anodic films that consisted of rutile and/or anatase phases with porous structures were formed on titanium metal after anodizing in H(2)SO(4) and Na(2)SO(4) electrolytes, while amorphous titania films were produced after anodizing in CH(3)COOH and H(3)PO(4) electrolytes. Titanium metal with the anatase and/or rutile crystal structure films showed excellent apatite-forming ability and produced a compact apatite layer covering all the surface of titanium after soaking in SBF for 7d, but titanium metal with amorphous titania layers was not able to induce apatite formation. The resultant apatite layer formed on titanium metal in SBF could enhance the bonding strength between living tissue and the implant. Anodic oxidation is believed to be an effective method for preparing bioactive titanium metal as an artificial bone substitute even under load-bearing conditions.

Electrical characteristic of the titanium mesh electrode for transcutaneous intrabody communication to monitor implantable artificial organs.

PubMed

Okamoto, Eiji; Kikuchi, Sakiko; Mitamura, Yoshinori

2016-09-01

We have developed a tissue-inducing electrode using titanium mesh to obtain mechanically and electrically stable contact with the tissue for a new transcutaneous communication system using the human body as a conductive medium. In this study, we investigated the electrical properties of the titanium mesh electrode by measuring electrode-tissue interface resistance in vivo. The titanium mesh electrode (Hi-Lex Co., Zellez, Hyogo, Japan) consisted of titanium fibers (diameter of 50 μm), and it has an average pore size of 200 μm and 87 % porosity. The titanium mesh electrode has a diameter of 5 mm and thickness of 1.5 mm. Three titanium mesh electrodes were implanted separately into the dorsal region of the rat. We measured the electrode-electrode impedance using an LCR meter for 12 weeks, and we calculated the tissue resistivity and electrode-tissue interface resistance. The electrode-tissue interface resistance of the titanium mesh electrode decreased slightly until the third POD and then continuously increased to 75 Ω. The electrode-tissue interface resistance of the titanium mesh electrode is stable and it has lower electrode-tissue interface resistance than that of a titanium disk electrode. The extracted titanium mesh electrode after 12 weeks implantation was fixed in 10 % buffered formalin solution and stained with hematoxylin-eosin. Light microscopic observation showed that the titanium mesh electrode was filled with connective tissue, inflammatory cells and fibroblasts with some capillaries in the pores of the titanium mesh. The results indicate that the titanium mesh electrode is a promising electrode for the new transcutaneous communication system.

FTIR absorption reflection study of biomimetic growth of phosphates on titanium implants

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzębski, W.; Brożek, A.; Stoch, J.; Szaraniec, J.; Trybalska, B.; Kmita, G.

2000-11-01

Titanium has been used for many medical applications; however, its joining to a living bone still is not satisfactorily good, challenging appropriate investigations. The aim of this work was to generate chemical modifications at its surface such that in vivo conditions, heterogeneous nucleation, and then growth of apatite from the body fluid could be easily induced and successfully performed. For this purpose, on the titanium samples, the oxide sublayers containing titanium, calcium and silicon (TCS) were deposited from a suitable solution using the sol-gel deep-coating procedure. Dried samples were heated at 400°C then cooled and thermostatically held in synthetic body fluids (SBF, SBFIII) under physiological conditions to mimic the natural process of apatite formation. Changes in surface composition of TCS sublayers caused by the heating were studied with XPS. Infrared spectroscopy and scanning electron microscopy monitored successive steps of apatite growth. It was found that in SBF, at the precoated titanium surface, nucleation and growth of the apatite containing carbonate took place. In SBFIII, for a higher concentration of calcium ions in comparison with SBF, a much-enhanced growth of the apatite free of carbonate was observed. TCS precoatings applied on stainless steel and Cr-Co-Mo alloy (Micromed) act also as bioactive interfaces with high ability to nucleation of biologically equivalent apatite. Biomimetic formation of this apatite on biologically inactive materials can be an important step in implant surgery.

Does titanium in ionic form display a tissue-specific distribution?

PubMed

Golasik, Magdalena; Wrobel, Pawel; Olbert, Magdalena; Nowak, Barbara; Czyzycki, Mateusz; Librowski, Tadeusz; Lankosz, Marek; Piekoszewski, Wojciech

2016-06-01

Most studies have focused on the biodistribution of titanium(IV) oxide as nanoparticles or crystals in organism. But several reports suggested that titanium is released from implant in ionic form. Therefore, gaining insight into toxicokinetics of Ti ions will give valuable information, which may be useful when assessing the health risks of long-term exposure to titanium alloy implants in patients. A micro synchrotron radiation-induced X-ray fluorescence (µ-SRXRF) was utilized to investigate the titanium distribution in the liver, spleen and kidneys of rats following single intravenous or 30-days oral administration of metal (6 mg Ti/b.w.) in ionic form. Titanium was mainly retained in kidneys after both intravenous and oral dosing, and also its compartmentalization in this organ was observed. Titanium in the liver was non-uniformly distributed-metal accumulated in single aggregates, and some of them were also enriched in calcium. Correlation analysis showed that metal did not displace essential elements, and in liver titanium strongly correlated with calcium. Two-dimensional maps of Ti distribution show that the location of the element is characteristic for the route of administration and time of exposure. We demonstrated that µ-SRXRF can provide information on the distribution of titanium in internal structures of whole organs, which helps in enhancing our understanding of the mechanism of ionic titanium accumulation in the body. This is significant due to the popularity of titanium implants and the potential release of metal ions from them to the organism.

Fretting and Corrosion in Modular Shoulder Arthroplasty: A Retrieval Analysis

PubMed Central

Panzram, Benjamin

2016-01-01

Tribocorrosion in taper junctions of retrieved anatomic shoulder arthroplasty implants was evaluated. A comparison of the tribocorrosion between cobalt-chromium and titanium alloy stems was conducted and the observations were correlated with the individual's clinical data. Adverse effects caused by metal debris and subsequent elevated serum metal ion levels are frequently reported in total hip arthroplasty. In total shoulder arthroplasty, to date only a small number of retrieval analyses are available and even fewer address the issue of tribocorrosion at the taper junctions. A total of 36 retrieved hemiarthroplasties and total shoulder arthroplasties were assessed using the modified Goldberg score. The prevalence of fretting and corrosion was confirmed in this cohort. Titanium stems seem to be more susceptible to damage caused by tribocorrosion than cobalt-chromium stems. Furthermore, stemless designs offered less tribocorrosion at the taper junction than stemmed designs. A weak correlation between time to revision and increased levels of tribocorrosion was seen. Whether or not tribocorrosion can lead to adverse clinical reactions and causes failure of shoulder arthroplasties remains to be examined. PMID:27433471

How to Choose between the Implant Materials Steel and Titanium in Orthopedic Trauma Surgery: Part 2 - Biological Aspects.

PubMed

Perren, S M; Regazzoni, P; Fernandez, A A

2017-01-01

BIOLOGICAL ASPECTS OF STEEL AND TITANIUM AS IMPLANT MATERIAL IN ORTHOPEDIC TRAUMA SURGERY The following case from the ICUC database, where a titanium plate was implanted into a flourishing infection, represents the clinical experience leading to preferring titanium over steel. (Fig. 1) (6). Current opinions regarding biological aspects of implant function. The "street" opinions regarding the biological aspects of the use of steel versus titanium as a surgical trauma implant material differ widely. Statements of opinion leaders range from "I do not see any difference in the biological behavior between steel and titanium in clinical application" to "I successfully use titanium implants in infected areas in a situation where steel would act as foreign body "sustaining" infection." Furthermore, some comments imply that clinical proof for the superiority of titanium in human application is lacking. The following tries to clarify the issues addressing the different aspects more through a practical clinical approach than a purely scientific one, this includes simplifications. Today's overall biocompatibility of implant materials is acceptable but: As the vast majority of secondary surgeries are elective procedures this allows the selection of implant materials with optimal infection resistance. The different biological reactions of stainless steel and titanium are important for this segment of clinical pathologies. Biological tole - rance (18) depends on the toxicity and on the amount of soluble implant material released. Release, diffusion and washout through blood circulation determine the local concentration of the corrosion products. Alloying components of steel, especially nickel and chromium, are less than optimal in respect to tissue tolerance and allergenicity. Titanium as a pure metal provides excellent biological tolerance (3, 4, 16). Better strength was obtained by titanium alloys like TiAl6V4. The latter found limited application as surgical implants. It contains Vanadium (9). Today's high strength titanium alloys contain well tolerated alloying components1 like Zr, Nb, Mo and Ta (ISO 5832-14) (7, 15). The corrosion rate of surgical implants is kept low by the passive layer formed when immerged in body fluids (13, 14). The passive layer may be locally destroyed, for instance, by mechanical fretting or by local corrosion conditions like in pitting; it is renewed by an electrochemical corrosion process which releases alloying components like Ni and Cr (Fig. 2) (10). The amount of soluble component may vary markedly depending on the local electrochemical conditions (see below).

Influence of Electropolishing and Magnetoelectropolishing on Corrosion and Biocompatibility of Titanium Implants

NASA Astrophysics Data System (ADS)

Rahman, Zia ur; Pompa, Luis; Haider, Waseem

2014-11-01

Titanium alloys are playing a vital role in the field of biomaterials due to their excellent corrosion resistance and biocompatibility. These alloys enhance the quality and longevity of human life by replacing or treating various parts of the body. However, as these materials are in constant contact with the aggressive body fluids, corrosion of these alloys leads to metal ions release. These ions leach to the adjacent tissues and result in adverse biological reactions and mechanical failure of implant. Surface modifications are used to improve corrosion resistance and biological activity without changing their bulk properties. In this investigation, electropolishing and magnetoelectropolishing were carried out on commercially pure titanium, Ti6Al4V, and Ti6Al4V-ELI. These surface modifications are known to effect surface charge, chemistry, morphology; wettability, corrosion resistance, and biocompatibility of these materials. In vitro cyclic potentiodynamic polarization tests were conducted in phosphate buffer saline in compliance with ASTM standard F-2129-12. The surface morphology, roughness, and wettability of these alloys were studied using scanning electron microscope, atomic force microscope, and contact angle meter, respectively. Moreover, biocompatibility of titanium alloys was assessed by growing MC3T3 pre-osteoblast cells on them.

Corrosion resistance and biological activity of TiO2 implant coatings produced in oxygen-rich environments.

PubMed

Zhang, Rui; Wan, Yi; Ai, Xing; Liu, Zhanqiang; Zhang, Dong

2017-01-01

The physical and chemical properties of bio-titanium alloy implant surfaces play an important role in their corrosion resistance and biological activity. New turning and turning-rolling processes are presented, employing an oxygen-rich environment in order to obtain titanium dioxide layers that can both protect implants from corrosion and also promote cell adhesion. The surface topographies, surface roughnesses and chemical compositions of the sample surfaces were obtained using scanning electron microscopy, a white light interferometer, and the Auger electron spectroscopy, respectively. The corrosion resistance of the samples in a simulated body fluid was determined using electrochemical testing. Biological activity on the samples was also analyzed, using a vitro cell culture system. The results show that compared with titanium oxide layers formed using a turning process in air, the thickness of the titanium oxide layers formed using turning and turning-rolling processes in an oxygen-rich environment increased by 4.6 and 7.3 times, respectively. Using an oxygen-rich atmosphere in the rolling process greatly improves the corrosion resistance of the resulting samples in a simulated body fluid. On samples produced using the turning-rolling process, cells spread quickly and exhibited the best adhesion characteristics.

Biomimetic Deposition of Hydroxyapatite by Mixed Acid Treatment of Titanium Surfaces.

PubMed

Zhao, J M; Park, W U; Hwang, K H; Lee, J K; Yoon, S Y

2015-03-01

A simple chemical method was established for inducing bioactivity of Ti metal. In the present study, two kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coatings successfully formed on the Ti surfaces in the simulated body fluid. Strong mixed acid etching was used to increase the roughness of the metal surface, because the porous and rough surfaces allow better adhesion between Ca-P coatings and substrate. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Some specimens were treated with a 5 M NaOH aqueous solution, and then heat treated at 600 °C in order to form an amorphous sodium titanate layer on their surface. This treated titanium metal is believed to form a dense and uniform bone-like apatite layer on its surface in a simulated body fluid (SBF). This study proved that mixed acid treatment is not only important for surface passivation but is also another bioactive treatment for titanium surfaces, an alternative to alkali treatment. In addition, mixed acid treatment uses a lower temperature and shorter time period than alkali treatment.

Ballistic Testing for Interceptor Body Armor Inserts Needs Improvement

DTIC Science & Technology

2011-08-01

030, “Ballistic Testing and Product Quality Surveillance for the Interceptor Body Armor - Vest Components Need Improvement,” January 3, 2011. This...Body Armor Ballistic Inserts Interceptor Body Armor (IBA) is a modular body armor system that consists of an outer tactical vest , ballistic inserts...altitude tests was because the ceramic ballistic inserts are solid structures that are not sensitive to reduced pressure and moisture. PM SEQ offered no

21 CFR 892.5730 - Radionuclide brachytherapy source.

Code of Federal Regulations, 2014 CFR

2014-04-01

... radionuclide which may be enclosed in a sealed container made of gold, titanium, stainless steel, or platinum and intended for medical purposes to be placed onto a body surface or into a body cavity or tissue as...

21 CFR 892.5730 - Radionuclide brachytherapy source.

Code of Federal Regulations, 2013 CFR

2013-04-01

... radionuclide which may be enclosed in a sealed container made of gold, titanium, stainless steel, or platinum and intended for medical purposes to be placed onto a body surface or into a body cavity or tissue as...

21 CFR 892.5730 - Radionuclide brachytherapy source.

Code of Federal Regulations, 2012 CFR

2012-04-01

... radionuclide which may be enclosed in a sealed container made of gold, titanium, stainless steel, or platinum and intended for medical purposes to be placed onto a body surface or into a body cavity or tissue as...

21 CFR 892.5730 - Radionuclide brachytherapy source.

Code of Federal Regulations, 2011 CFR

2011-04-01

... radionuclide which may be enclosed in a sealed container made of gold, titanium, stainless steel, or platinum and intended for medical purposes to be placed onto a body surface or into a body cavity or tissue as...

Cranial and mandibular shape variation in the genus Carollia (Mammalia: Chiroptera) from Colombia: biogeographic patterns and morphological modularity.

PubMed

López-Aguirre, Camilo; Pérez-Torres, Jairo; Wilson, Laura A B

2015-01-01

Neotropical bats of the genus Carollia are widely studied due to their abundance, distribution and relevance for ecosystems. However, the ecomorphological boundaries of these species are poorly differentiated, and consequently correspondence between their geographic distribution, ecological plasticity and morphological variation remains unclear. In this study, patterns of cranial and mandibular morphological variation were assessed for Carollia brevicauda, C. castanea and C. perspicillata from Colombia. Using geometric morphometrics, morphological variation was examined with respect to: differences in intraspecific variation, morphological modularity and integration, and biogeographic patterns. Patterns of intraspecific variation were different for each species in both cranial and mandibular morphology, with functional differences apparent according to diet. Cranial modularity varied between species whereas mandibular modularity did not. High cranial and mandibular correlation reflects Cranium-Mandible integration as a functional unit. Similarity between the biogeographic patterns in C. brevicauda and C. perspicillata indicates that the Andes do not act as a barrier but rather as an independent region, isolating the morphology of Andean populations of larger-bodied species. The biogeographic pattern for C. castanea was not associated with the physiography of the Andes, suggesting that large body size does not benefit C. brevicauda and C. perspicillata in maintaining homogeneous morphologies among populations.

Cranial and mandibular shape variation in the genus Carollia (Mammalia: Chiroptera) from Colombia: biogeographic patterns and morphological modularity

PubMed Central

Pérez-Torres, Jairo; Wilson, Laura A. B.

2015-01-01

Neotropical bats of the genus Carollia are widely studied due to their abundance, distribution and relevance for ecosystems. However, the ecomorphological boundaries of these species are poorly differentiated, and consequently correspondence between their geographic distribution, ecological plasticity and morphological variation remains unclear. In this study, patterns of cranial and mandibular morphological variation were assessed for Carollia brevicauda, C. castanea and C. perspicillata from Colombia. Using geometric morphometrics, morphological variation was examined with respect to: differences in intraspecific variation, morphological modularity and integration, and biogeographic patterns. Patterns of intraspecific variation were different for each species in both cranial and mandibular morphology, with functional differences apparent according to diet. Cranial modularity varied between species whereas mandibular modularity did not. High cranial and mandibular correlation reflects Cranium-Mandible integration as a functional unit. Similarity between the biogeographic patterns in C. brevicauda and C. perspicillata indicates that the Andes do not act as a barrier but rather as an independent region, isolating the morphology of Andean populations of larger-bodied species. The biogeographic pattern for C. castanea was not associated with the physiography of the Andes, suggesting that large body size does not benefit C. brevicauda and C. perspicillata in maintaining homogeneous morphologies among populations. PMID:26413433

Subcommunities and Their Mutual Relationships in a Transaction Network

NASA Astrophysics Data System (ADS)

Iino, T.; Iyetomi, H.

We investigate a Japanese transaction network consisting ofabout 800 thousand firms (nodes) and four million business relations (links) with focus on its modular structure. Communities detected by maximizing modularity often are dominated by firms with common features or behaviors in the network, such as characterized by regions or industry sectors. However, it is well known that the modularity optimization approach has a resolution limit problem, that is, it fails in identifying fine communities buried in large communities. To unfold such hidden structures, we apply the community detection to each of subnetworks formed by isolating those communities from the whole body. Subcommunities thus identified are composed of firms with finer regions, more specified sectors or business affiliations. Also we introduce a new idea of reduced modularity matrix to measure the strength of relations between (sub)communities.

Hybrid Calcium Phosphate Coatings for Titanium Implants

NASA Astrophysics Data System (ADS)

Kharapudchenko, E.; Ignatov, V.; Ivanov, V.; Tverdokhlebov, S.

2017-01-01

Hybrid multilayer coatings were obtained on titanium substrates by the combination of two methods: the micro-arc oxidation in phosphoric acid solution with the addition of calcium compounds to high supersaturated state and RF magnetron sputtering of the target made of synthetic hydroxyapatite. 16 different groups of coatings were formed on titanium substrates and in vitro studies were conducted in accordance with ISO 23317 in the solution simulating body fluid. The studies using SEM, XRD of the coatings of the samples before and after exposure to SBF were performed. The features of morphology, chemical and phase composition of the studied coatings are shown.

Titanium reinforced boron-polyimide composite

NASA Technical Reports Server (NTRS)

Clark, G. A.; Clayton, K. I.

1969-01-01

Processing techniques for boron polyimide prepreg were developed whereby composites could be molded under vacuum bag pressure only. A post-cure cycle was developed which resulted in no loss in room temperature mechanical properties of the composite at any time during up to 16 hours at 650 F. A design utilizing laminated titanium foil was developed to achieve a smooth transition of load from the titanium attachment points into the boron-reinforced body of the structure. The box beam test article was subjected to combined bending and torsional loads while exposed to 650 F. Loads were applied incrementally until failure occurred at 83% design limit load.

[Long-term follow-up study of titanium implant impact on pediatric mandibular growth and development].

PubMed

Hu, Yun; Li, Wei; Chen, Qi; Song, Fumin; Tang, Wei; Wang, Hang

2015-08-01

To explore the impact of titanium implant on the growth and development of pediatric mandible after suffering from mandibular fracture and undergoing open reduction and internal fixation (ORIF) compared with those that underwent titanium plate removal postoperatively. Fifteen pediatric patients with mandibular fracture who underwent ORIF were included in this study. Eight patients did not undergo titanium implant removal postoperatively, whereas the other seven patients underwent the routine. The postoperative data of the pediatrics were collected for comparative analysis by taking the patients' frontal and lateral photos, recording the inter-incisor distance, and measuring the height of mandibular ramus, length of the mandibular body, and combined length of the mandible in three-dimensional reconstruction image. All patients had acceptable facial contour, mouth opening, and occlusion, without obvious abnormalities. The radiography showed no significant difference between the bilateral mandibular lengths in the two groups of patients (P>0.05). The titanium plants have no significant impact on the growth and development of pediatric mandible postoperatively; hence, the question on whether the titanium plates should be removed or not may be neglected. The removal operation may lead to secondary trauma; thus, performing titanium plate removal routinely is not recommended.

Medical equipment bio-capability processes using the atmospheric plasma-sprayed titanium coating

NASA Astrophysics Data System (ADS)

Rezaei, F.; Saviz, S.; Ghoranneviss, M.

2017-12-01

Antibacterial surfaces such as titanium coatings are able to have capability in the human body environment. In this study, titanium coatings are deposited on the 316 stainless steel substrates by a handmade plasma spray system. Some mechanical, chemical properties and microstructure of the created titanium layer are determined to evaluate the quality of coating. The XRD, SEM, adhesion tests from cross cut and corrosion test by potentiodynamic are used. During the different stages, some of the parameters are changed in different samples to achieve the best quality in the coating. It is shown that by increasing the spray time, the production of nanoparticles begins. On the other hand, the best layers are created when the spray main gas flow rate has a certain amount.

The development of whole blood titanium levels after instrumented spinal fusion – Is there a correlation between the number of fused segments and titanium levels?

PubMed Central

2012-01-01

Background Most modern spinal implants contain titanium and remain in the patient’s body permanently. Local and systemic effects such as tissue necrosis, osteolysis and malignant cell transformation caused by implants have been described. Increasing tissue concentration and whole blood levels of ions are necessary before a disease caused by a contaminant develops. The aim of the present study was the measurement of whole blood titanium levels and the evaluation of a possible correlation between these changes and the number of fused segments. Methods A prospective study was designed to determine changes in whole blood titanium levels after spinal fusion and to analyze the correlation to the number of pedicle screws, cross connectors and interbody devices implanted. Blood samples were taken preoperatively in group I (n = 15), on the first, second and 10th day postoperatively, as well as 3 and 12 months after surgery. Group II (n = 16) served as a control group of volunteers who did not have any metal implants in the body. Blood samples were taken once in this group. The number of screw-rod-connections and the length of the spinal fusion were determined using radiographic pictures. This study was checked and approved by the ethical committee of the University of Tuebingen. Results The mean age in group I was 47 ± 22 years (range 16 - 85 years). There were three male (20%) and twelve female (80%) patients. The median number of fused segments was 5 (range 1 to 11 segments). No statistically significant increase in the titanium level was seen 12 months after surgery (mean difference: -7.2 μg/l, 95% CI: -26.9 to 12.5 μg/l, p = 0.446). By observing the individual titanium levels, 4 out of 15 patients demonstrated an increase in titanium levels 12 months after surgery. No statistically significant correlation between fused segments (r = -0.188, p = 0.503) length of instrumentation (r = -0.329, p = 0.231), number of interbody devices (r = -0.202, p = 0.291) and increase of titanium levels over the observation period was seen. Conclusions Instrumented spinal fusion does not lead to a statistically significant increase in whole blood titanium levels. There seems to be no correlation between the number of pedicle screws, cross connectors and interbody devices implanted and the increase of serum titanium levels. PMID:22925526

Corrosion Analysis of an Experimental Noble Alloy on Commercially Pure Titanium Dental Implants

PubMed Central

Bortagaray, Manuel Alberto; Ibañez, Claudio Arturo Antonio; Ibañez, Maria Constanza; Ibañez, Juan Carlos

2016-01-01

Objective: To determine whether the Noble Bond® Argen® alloy was electrochemically suitable for the manufacturing of prosthetic superstructures over commercially pure titanium (c.p. Ti) implants. Also, the electrolytic corrosion effects over three types of materials used on prosthetic suprastructures that were coupled with titanium implants were analysed: Noble Bond® (Argen®), Argelite 76sf +® (Argen®), and commercially pure titanium. Materials and Methods: 15 samples were studied, consisting in 1 abutment and one c.p. titanium implant each. They were divided into three groups, namely: Control group: five c.p Titanium abutments (B&W®), Test group 1: five Noble Bond® (Argen®) cast abutments and, Test group 2: five Argelite 76sf +® (Argen®) abutments. In order to observe the corrosion effects, the surface topography was imaged using a confocal microscope. Thus, three metric parameters (Sa: Arithmetical mean height of the surface. Sp: Maximum height of peaks. Sv: Maximum height of valleys.), were measured at three different areas: abutment neck, implant neck and implant body. The samples were immersed in artificial saliva for 3 months, after which the procedure was repeated. The metric parameters were compared by statistical analysis. Results: The analysis of the Sa at the level of the implant neck, abutment neck and implant body, showed no statistically significant differences on combining c.p. Ti implants with the three studied alloys. The Sp showed no statistically significant differences between the three alloys. The Sv showed no statistically significant differences between the three alloys. Conclusion: The effects of electrogalvanic corrosion on each of the materials used when they were in contact with c.p. Ti showed no statistically significant differences. PMID:27733875

Thin calcium phosphate coatings on titanium by electrochemical deposition in modified simulated body fluid.

PubMed

Peng, Ping; Kumar, Sunil; Voelcker, Nicolas H; Szili, Endre; Smart, Roger St C; Griesser, Hans J

2006-02-01

Adherent and optically semitransparent thin calcium phosphate (CaP) films were electrochemically deposited on titanium substrates in a modified simulated body fluid at 37 degrees C. Coatings deposited by using periodic pulsed potentials showed better adhesion and better mechanical properties than coatings deposited with use of a constant potential. Scanning electron microscopy was used to study the morphology of the coatings. The coatings displayed a polydispersed porous structure with pores in the range of a few nanometers to 1 mum. Furthermore, X-ray diffractometry and the O(1s) satellite peaks in X-ray photoelectron spectroscopy indicated that the coatings possessed a similar surface chemistry to that of natural bone minerals. These results were confirmed by inductively coupled plasma optical emission spectrometry, which yielded a Ca:P ratio of 1.65, close to that of hydroxyapatite. Contact mode atomic force microscopy (AFM) showed the average thickness of the coatings was in the order of 200 nm. Root-mean-square (RMS) roughness values, also derived by AFM, were shown to be much higher on the titanium-CaP surfaces in comparison with untreated titanium substrates, with RMS values of about 300 and 110 nm, respectively. Cell culture experiments showed that the CaP surfaces are nontoxic to MG63 osteoblastic cells in vitro and were able to support cell growth for up to 4 days, outperforming the untreated titanium surface in a direct comparison. These easily prepared coatings show promise for hard-tissue biomaterials. (c) 2005 Wiley Periodicals, Inc.

Difference in metallic wear distribution released from commercially pure titanium compared with stainless steel plates.

PubMed

Krischak, G D; Gebhard, F; Mohr, W; Krivan, V; Ignatius, A; Beck, A; Wachter, N J; Reuter, P; Arand, M; Kinzl, L; Claes, L E

2004-03-01

Stainless steel and commercially pure titanium are widely used materials in orthopedic implants. However, it is still being controversially discussed whether there are significant differences in tissue reaction and metallic release, which should result in a recommendation for preferred use in clinical practice. A comparative study was performed using 14 stainless steel and 8 commercially pure titanium plates retrieved after a 12-month implantation period. To avoid contamination of the tissue with the elements under investigation, surgical instruments made of zirconium dioxide were used. The tissue samples were analyzed histologically and by inductively coupled plasma atomic emission spectrometry (ICP-AES) for accumulation of the metals Fe, Cr, Mo, Ni, and Ti in the local tissues. Implant corrosion was determined by the use of scanning electron microscopy (SEM). With grades 2 or higher in 9 implants, steel plates revealed a higher extent of corrosion in the SEM compared with titanium, where only one implant showed corrosion grade 2. Metal uptake of all measured ions (Fe, Cr, Mo, Ni) was significantly increased after stainless steel implantation, whereas titanium revealed only high concentrations for Ti. For the two implant materials, a different distribution of the accumulated metals was found by histological examination. Whereas specimens after steel implantation revealed a diffuse siderosis of connective tissue cells, those after titanium exhibited occasionally a focal siderosis due to implantation-associated bleeding. Neither titanium- nor stainless steel-loaded tissues revealed any signs of foreign-body reaction. We conclude from the increased release of toxic, allergic, and potentially carcinogenic ions adjacent to stainless steel that commercially pure Ti should be treated as the preferred material for osteosyntheses if a removal of the implant is not intended. However, neither material provoked a foreign-body reaction in the local tissues, thus cpTi cannot be recommend as the 'golden standard' for osteosynthesis material in general.

iBodies: Modular Synthetic Antibody Mimetics Based on Hydrophilic Polymers Decorated with Functional Moieties.

PubMed

Šácha, Pavel; Knedlík, Tomáš; Schimer, Jiří; Tykvart, Jan; Parolek, Jan; Navrátil, Václav; Dvořáková, Petra; Sedlák, František; Ulbrich, Karel; Strohalm, Jiří; Majer, Pavel; Šubr, Vladimír; Konvalinka, Jan

2016-02-12

Antibodies are indispensable tools for biomedicine and anticancer therapy. Nevertheless, their use is compromised by high production costs, limited stability, and difficulty of chemical modification. The design and preparation of synthetic polymer conjugates capable of replacing antibodies in biomedical applications such as ELISA, flow cytometry, immunocytochemistry, and immunoprecipitation is reported. The conjugates, named "iBodies", consist of an HPMA copolymer decorated with low-molecular-weight compounds that function as targeting ligands, affinity anchors, and imaging probes. We prepared specific conjugates targeting several proteins with known ligands and used these iBodies for enzyme inhibition, protein isolation, immobilization, quantification, and live-cell imaging. Our data indicate that this highly modular and versatile polymer system can be used to produce inexpensive and stable antibody substitutes directed toward virtually any protein of interest with a known ligand. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

A wireless modular multi-modal multi-node patch platform for robust biosignal monitoring.

PubMed

Pantelopoulos, Alexandros; Saldivar, Enrique; Roham, Masoud

2011-01-01

In this paper a wireless modular, multi-modal, multi-node patch platform is described. The platform comprises low-cost semi-disposable patch design aiming at unobtrusive ambulatory monitoring of multiple physiological parameters. Owing to its modular design it can be interfaced with various low-power RF communication and data storage technologies, while the data fusion of multi-modal and multi-node features facilitates measurement of several biosignals from multiple on-body locations for robust feature extraction. Preliminary results of the patch platform are presented which illustrate the capability to extract respiration rate from three different independent metrics, which combined together can give a more robust estimate of the actual respiratory rate.

Comparative Evaluation of Fracture Resistance and Mode of Failure of Zirconia and Titanium Abutments with Different Diameters.

PubMed

Shabanpour, Reza; Mousavi, Niloufar; Ghodsi, Safoura; Alikhasi, Marzieh

2015-08-01

The purpose of the current study was to compare the fracture resistance and mode of failure of zirconia and titanium abutments with different diameters. Fourteen groups of abutments including prefabricated zirconia, copy-milled zirconia and titanium abutments of an implant system (XiVE, Dentsply) were prepared in different diameters. An increasing vertical load was applied to each specimen until failure occurred. Fracture resistance was measured in each group using the universal testing machine. Moreover, the failure modes were studied and categorized as abutment screw fracture, connection area fracture, abutment body fracture, abutment body distortion, screw distortion and connection area distortion. Groups were statistically compared using univariate and post-hoc tests. The level of statistical significance was set at 5%. Fabrication method (p = 0.03) and diameter (p < 0.001) had significant effect on the fracture resistance of abutments. Fracture resistance of abutments with 5.5 mm diameter was higher than other diameters (p < 0.001). The observed modes of failure were dependent on the abutment material as well. All of the prefabricated titanium abutments fractured within the abutment screw. Abutment screw distortion, connection area fracture, and abutment body fracture were the common failure type in other groups. Diameter had a significant effect on fracture resistance of implant abutments, as abutments with greater diameters were more resistant to static loads. Copy-milled abutments showed lower fracture resistance as compared to other experimental groups. Although zirconia abutments have received great popularity among clinicians and even patients selecting them for narrow implants should be with caution.

Thermal and aerothermal performance of a titanium multiwall thermal protection system

NASA Technical Reports Server (NTRS)

Avery, D. E.; Shideler, J. L.; Stuckey, R. N.

1981-01-01

A metallic thermal protection system (TPS) concept the multiwall designed for temperature and pressure at Shuttle body point 3140 where the maximum surface temperature is approximately 811 K was tested to evaluate thermal performance and structural integrity. A two tile model of titanium multiwall and a model consisting of a low temperature reusable surface insulation (LRSI) tiles were exposed to 25 simulated thermal and pressure Shuttle entry missions. The two systems performed the same, and neither system deteriorated during the tests. It is indicated that redesign of the multiwall tiles reduces tile thickness and/or weight. A nine tile model of titanium multiwal was tested for radiant heating and aerothermodynamics. Minor design changes that improve structural integrity without having a significant impact on the thermal protection ability of the titanium multiwall TPS are identified. The capability of a titanium multiwall thermal protection system to protect an aluminum surface during a Shuttle type entry trajectory at locations on the vehicle where the maximum surface temperature is below 811 K is demonstrated.

Bioactive borate glass coatings for titanium alloys.

PubMed

Peddi, Laxmikanth; Brow, Richard K; Brown, Roger F

2008-09-01

Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na(2)O-CaO-B(2)O(3) system, modified by additions of SiO(2), Al(2)O(3), and P(2)O(5), were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37 degrees C; similar layers form on 45S5 Bioglass((R)) exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass((R)). An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 +/- 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.

Ternary boride product and process

NASA Technical Reports Server (NTRS)

Clougherty, Edward V. (Inventor)

1976-01-01

A hard, tough, strong ceramic body is formed by hot pressing a mixture of a powdered metal and a powdered metal diboride. The metal employed is zirconium, titanium or hafnium and the diboride is the diboride of a different member of the same group of zirconium, titanium or hafnium to form a ternary composition. During hot pressing at temperatures above about 2,000.degree.F., a substantial proportion of acicular ternary monoboride is formed.

Battery with modular air cathode and anode cage

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.

1987-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Battery with modular air cathode and anode cage

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.; Turk, Thomas R.

1988-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Modularization and Validation of FUN3D as a CREATE-AV Helios Near-Body Solver

NASA Technical Reports Server (NTRS)

Jain, Rohit; Biedron, Robert T.; Jones, William T.; Lee-Rausch, Elizabeth M.

2016-01-01

Under a recent collaborative effort between the US Army Aeroflightdynamics Directorate (AFDD) and NASA Langley, NASA's general unstructured CFD solver, FUN3D, was modularized as a CREATE-AV Helios near-body unstructured grid solver. The strategies adopted in Helios/FUN3D integration effort are described. A validation study of the new capability is performed for rotorcraft cases spanning hover prediction, airloads prediction, coupling with computational structural dynamics, counter-rotating dual-rotor configurations, and free-flight trim. The integration of FUN3D, along with the previously integrated NASA OVERFLOW solver, lays the ground for future interaction opportunities where capabilities of one component could be leveraged with those of others in a relatively seamless fashion within CREATE-AV Helios.

Titanium Nitride: An Oxidizable Coating for the High-Temperature Protection of Graphite

NASA Technical Reports Server (NTRS)

Wakelyn, N. T.

1961-01-01

A titanium nitride coating for graphite, prepared by deposition process, protected test specimens for 60 seconds the vapors in a supersonic ceramic-heated air jet with a stagnation temperature of approximately 2,250 K. For the same test conditions, coated specimens showed no damage to the graphite body for the 60-second test, whereas uncoated specimens were very severely damaged after 20 seconds and were destroyed toward the end of the test. A discussion of the coating of these graphite specimens and of some of the conditions necessary for the utilization of oxidizable substances as oxidation-protective coatings for bodies facing high convective heat transfer in the atmosphere is presented.

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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.

The Effects of Different Wavelength UV Photofunctionalization on Micro-Arc Oxidized Titanium

PubMed Central

Zhou, Lei; Guo, Zehong; Rong, Mingdeng; Liu, Xiangning; Lai, Chunhua; Ding, Xianglong

2013-01-01

Many challenges exist in improving early osseointegration, one of the most critical factors in the long-term clinical success of dental implants. Recently, ultraviolet (UV) light-mediated photofunctionalization of titanium as a new potential surface treatment has aroused great interest. This study examines the bioactivity of titanium surfaces treated with UV light of different wavelengths and the underlying associated mechanism. Micro-arc oxidation (MAO) titanium samples were pretreated with UVA light (peak wavelength of 360 nm) or UVC light (peak wavelength of 250 nm) for up to 24 h. UVC treatment promoted the attachment, spread, proliferation and differentiation of MG-63 osteoblast-like cells on the titanium surface, as well as the capacity for apatite formation in simulated body fluid (SBF). These biological influences were not observed after UVA treatment, apart from a weaker effect on apatite formation. The enhanced bioactivity was substantially correlated with the amount of Ti-OH groups, which play an important role in improving the hydrophilicity, along with the removal of hydrocarbons on the titanium surface. Our results showed that both UVA and UVC irradiation altered the chemical properties of the titanium surface without sacrificing its excellent physical characteristics, suggesting that this technology has extensive potential applications and merits further investigation. PMID:23861853

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

PubMed

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.

Ballistic Testing and Product Quality Surveillance for the Interceptor Body Armor - Vest Components Need Improvement

DTIC Science & Technology

2011-01-03

six contracts. Interceptor Body Armor – Vest Components IBA is a modular body armor system that consists of an OTV, ceramic plates , and components...Armor - Vest Components Need Improvement Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the...Ballistic Testing and Product Quality Surveillance for the Interceptor Body Armor - Vest Components Need Improvement 5a. CONTRACT NUMBER 5b. GRANT

Modularized and water-cooled photo-catalyst cleaning devices for aquaponics based on ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Yang, Henglong; Lung, Louis; Wei, Yu-Chien; Huang, Yi-Bo; Chen, Zi-Yu; Chou, Yu-Yang; Lin, Anne-Chin

2017-08-01

The feasibility of applying ultraviolet light-emitting diodes (UV-LED's) as triggering sources of photo-catalyst based on titanium dioxide (TiO2) nano-coating specifically for water-cleaning process in an aquaponics system was designed and proposed. The aquaponics system is a modern farming system to integrate aquaculture and hydroponics into a single system to establish an environmental-friendly and lower-cost method for farming fish and vegetable all together in urban area. Water treatment in an aquaponics system is crucial to avoid mutual contamination. we proposed a modularized watercleaning device composed of all commercially available components and parts to eliminate organic contaminants by using UV-LED's for TiO2 photo-catalyst reaction. This water-cleaning module consisted of two coaxial hollowed cylindrical pipes can be submerged completely in water for water treatment and cooling UV-LED's. The temperature of the UV-LED after proper thermal management can be reduced about 16% to maintain the optimal operation condition. Our preliminary experimental result by using Methylene Blue solution to simulate organic contaminants indicated that TiO2 photo-catalyst triggered by UV-LED's can effectively decompose organic compound and decolor Methylene Blue solution.

Effect of Wheelchair Frame Material on Users' Mechanical Work and Transmitted Vibration

PubMed Central

Aissaoui, Rachid

2014-01-01

Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO 2631-1:1997. Reducing the mechanical work required to travel a given distance (WN-WPM, weight-normalized work-per-meter) can help reduce the risk of shoulder injury, while reducing the vibration transmissibility (VT) of the wheelchair frame can reduce whole-body vibration. New materials such as titanium and carbon are used in today's wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs (1 titanium, 1 carbon, and 4 aluminium). Ten able-bodied users propelled the six wheelchairs on three ground surfaces. Although no significant difference of WN-WPM was found between wheelchairs (P < 0.1), significant differences of VT were found (P < 0.05). The carbon wheelchair had the lowest VT. Contrarily to current belief, the titanium wheelchair VT was similar to aluminium wheelchairs. A negative correlation between VT and WN-WPM was found, which means that reducing VT may be at the expense of increasing WN-WPM. Based on our results, use of carbon in wheelchair construction seems promising to reduce VT without increasing WN-WPM. PMID:25276802

Method of preparation of novel fiber reinforced titanium diboride composite bodies and uses therefor

DOEpatents

Newkirk, L.C.; Riley, R.E.; Valencia, F.A.; Wallace, T.C. Sr.

Cloth is coated with titanium diboride in a chemical vapor deposition reaction under particular coating conditions which result in a uniform coating on the individual filaments making up the cloth fiber bundles. The coated cloth can be used as deposited as electrodes, for example, or can be hot pressed to form highly spall-resistant structures having special utility in fusion reactors, for example, as wall armor.

Biodegradable magnesium-based screw clinically equivalent to titanium screw in hallux valgus surgery: short term results of the first prospective, randomized, controlled clinical pilot study

PubMed Central

2013-01-01

Purpose Nondegradable steel-and titanium-based implants are commonly used in orthopedic surgery. Although they provide maximal stability, they are also associated with interference on imaging modalities, may induce stress shielding, and additional explantation procedures may be necessary. Alternatively, degradable polymer implants are mechanically weaker and induce foreign body reactions. Degradable magnesium-based stents are currently being investigated in clinical trials for use in cardiovascular medicine. The magnesium alloy MgYREZr demonstrates good biocompatibility and osteoconductive properties. The aim of this prospective, randomized, clinical pilot trial was to determine if magnesium-based MgYREZr screws are equivalent to standard titanium screws for fixation during chevron osteotomy in patients with a mild hallux valgus. Methods Patients (n=26) were randomly assigned to undergo osteosynthesis using either titanium or degradable magnesium-based implants of the same design. The 6 month follow-up period included clinical, laboratory, and radiographic assessments. Results No significant differences were found in terms of the American Orthopaedic Foot and Ankle Society (AOFAS) score for hallux, visual analog scale for pain assessment, or range of motion (ROM) of the first metatarsophalangeal joint (MTPJ). No foreign body reactions, osteolysis, or systemic inflammatory reactions were detected. The groups were not significantly different in terms of radiographic or laboratory results. Conclusion The radiographic and clinical results of this prospective controlled study demonstrate that degradable magnesium-based screws are equivalent to titanium screws for the treatment of mild hallux valgus deformities. PMID:23819489

Biological Behavior of Osteoblast Cell and Apatite Forming Ability of the Surface Modified Ti Alloys.

PubMed

Zhao, Jingming; Hwang, K H; Choi, W S; Shin, S J; Lee, J K

2016-02-01

Titanium as one kind of biomaterials comes in direct contact with the body, making evaluation of biocompatibility an important aspect to biomaterials development. Surface chemistry of titanium plays an important role in osseointegration. Different surface modification alters the surface chemistry and result in different biological response. In this study, three kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coating successfully formed on the Ti surfaces in simulated body fluid. Strong mixed acid increased the roughness of the metal surface, because the porous and rough surface allows better adhesion between Ca-P coatings and substrates. After modification of titanium surface by mixed acidic solution and subsequently H2O2/HCL treatment evaluation of biocompatibility was conducted from hydroxyapatite formation by biomimetic process and cell viability on modified titanium surface. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Results from this study indicated that surface treatment methods affect the surface morphology, type of TiO2 layer formed and subsequent apatite deposition and biological responses. The thermo scientific alamarblue cell viability assay reagent is used to quantitatively measure the viability of mammalian cell lines, bacteria and fungi by incorporating a rapid, sensitive and reliable fluorometric/colorimetric growth indicator, without any toxic and side effect to cell line. In addition, mixed acid treatment uses a lower temperature and shorter time period than widely used alkali treatment.

Towards modular bone tissue engineering using Ti-Co-doped phosphate glass microspheres: cytocompatibility and dynamic culture studies.

PubMed

Peticone, Carlotta; De Silva Thompson, David; Owens, Gareth J; Kim, Hae-Won; Micheletti, Martina; Knowles, Jonathan C; Wall, Ivan

2017-09-01

The production of large quantities of functional vascularized bone tissue ex vivo still represent an unmet clinical challenge. Microcarriers offer a potential solution to scalable manufacture of bone tissue due to their high surface area-to-volume ratio and the capacity to be assembled using a modular approach. Microcarriers made of phosphate bioactive glass doped with titanium dioxide have been previously shown to enhance proliferation of osteoblast progenitors and maturation towards functional osteoblasts. Furthemore, doping with cobalt appears to mimic hypoxic conditions that have a key role in promoting angiogenesis. This characteristic could be exploited to meet the clinical requirement of producing vascularized units of bone tissue. In the current study, the human osteosarcoma cell line MG-63 was cultured on phosphate glass microspheres doped with 5% mol titanium dioxide and different concentrations of cobalt oxide (0%, 2% and 5% mol), under static and dynamic conditions (150 and 300 rpm on an orbital shaker). Cell proliferation and the formation of aggregates of cells and microspheres were observed over a period of two weeks in all glass compositions, thus confirming the biocompatibility of the substrate and the suitability of this system for the formation of compact micro-units of tissue. At the concentrations tested, cobalt was not found to be cytotoxic and did not alter cell metabolism. On the other hand, the dynamic environment played a key role, with moderate agitation having a positive effect on cell proliferation while higher agitation resulting in impaired cell growth. Finally, in static culture assays, the capacity of cobalt doping to induce vascular endothelial growth factor (VEGF) upregulation by osteoblastic cells was observed, but was not found to increase linearly with cobalt oxide content. In conclusion, Ti-Co phosphate glasses were found to support osteoblastic cell growth and aggregate formation that is a necessary precursor to tissue formation and the upregaulation of VEGF production can potentially support vascularization.

Motor modules in robot-aided walking

PubMed Central

2012-01-01

Background It is hypothesized that locomotion is achieved by means of rhythm generating networks (central pattern generators) and muscle activation generating networks. This modular organization can be partly identified from the analysis of the muscular activity by means of factorization algorithms. The activity of rhythm generating networks is described by activation signals whilst the muscle intervention generating network is represented by motor modules (muscle synergies). In this study, we extend the analysis of modular organization of walking to the case of robot-aided locomotion, at varying speed and body weight support level. Methods Non Negative Matrix Factorization was applied on surface electromyographic signals of 8 lower limb muscles of healthy subjects walking in gait robotic trainer at different walking velocities (1 to 3km/h) and levels of body weight support (0 to 30%). Results The muscular activity of volunteers could be described by low dimensionality (4 modules), as for overground walking. Moreover, the activation signals during robot-aided walking were bursts of activation timed at specific phases of the gait cycle, underlying an impulsive controller, as also observed in overground walking. This modular organization was consistent across the investigated speeds, body weight support level, and subjects. Conclusions These results indicate that walking in a Lokomat robotic trainer is achieved by similar motor modules and activation signals as overground walking and thus supports the use of robotic training for re-establishing natural walking patterns. PMID:23043818

A process for the production of a scale-proof and corrosion-resistant coating on graphite and carbon bodies

NASA Technical Reports Server (NTRS)

Fitzer, E.

1981-01-01

A process for the production of a corrosion resistant coating on graphite and carbon bodies is described. The carbon or graphite body is coated or impregnated with titanium silicide under the addition of a metal containing wetting agent in a nitrogen free atmosphere, so that a tight coating is formed.

[Utility of nickel-titanium shape memory alloys of vertebral body reduction fixator with assisted distraction bar].

PubMed

Man, Yi; Zheng, Yue-huan; Cao, Peng; Chen, Bo; Zheng, Tao; Sun, Chang-hui; Lu, Jiong

2011-06-07

To test the nickel-titanium (Ni-Ti) shape memory alloys of vertebral body reduction fixator with assisted distraction bar for the treatment of traumatic and osteoporotic vertebral body fracture. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar was implanted into the compressed fracture specimens through vertebral pedicle with the radiographic monitoring to reduce the collapsed endplate as well as distract the compressed vertebral fracture. Radiographic film and computed tomographic reconstruction technique were employed to evaluate the effects of reduction and distraction. A biomechanic test machine was used to measure the fatigue and the stability of deformation of fixation segments. Relying on the effect of temperature shape memory, such an assembly could basically reduce the collapsed endplate as well as distract the compressed vertebral fracture. And when unsatisfied results of reduction and distraction occurred, its super flexibility could provide additional distraction strength. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar may provide effective endplate reduction, restore the vertebral height and the immediate biomechanic spinal stability. So the above assembly is indicated for the treatment of traumatic and osteoporotic vertebral body fracture.

Non-Destructive Analysis of Basic Surface Characteristics of Titanium Dental Implants Made by Miniature Machining

NASA Astrophysics Data System (ADS)

Babík, Ondrej; Czán, Andrej; Holubják, Jozef; Kameník, Roman; Pilc, Jozef

2016-12-01

One of the most best-known characteristic and important requirement of dental implant is made of biomaterials ability to create correct interaction between implant and human body. The most implemented material in manufacturing of dental implants is titanium of different grades of pureness. Since most of the implant surface is in direct contact with bone tissue, shape and integrity of said surface has great influence on the successful osseointegration. Among other characteristics of titanium that predetermine ideal biomaterial, it shows a high mechanical strength making precise machining miniature Increasingly difficult. The article is focused on evaluation of the resulting quality, integrity and characteristics of dental implants surface after machining.

Mergeable nervous systems for robots.

PubMed

Mathews, Nithin; Christensen, Anders Lyhne; O'Grady, Rehan; Mondada, Francesco; Dorigo, Marco

2017-09-12

Robots have the potential to display a higher degree of lifetime morphological adaptation than natural organisms. By adopting a modular approach, robots with different capabilities, shapes, and sizes could, in theory, construct and reconfigure themselves as required. However, current modular robots have only been able to display a limited range of hardwired behaviors because they rely solely on distributed control. Here, we present robots whose bodies and control systems can merge to form entirely new robots that retain full sensorimotor control. Our control paradigm enables robots to exhibit properties that go beyond those of any existing machine or of any biological organism: the robots we present can merge to form larger bodies with a single centralized controller, split into separate bodies with independent controllers, and self-heal by removing or replacing malfunctioning body parts. This work takes us closer to robots that can autonomously change their size, form and function.Robots that can self-assemble into different morphologies are desired to perform tasks that require different physical capabilities. Mathews et al. design robots whose bodies and control systems can merge and split to form new robots that retain full sensorimotor control and act as a single entity.

Large Diameter Femoral Heads Impose Significant Alterations on the Strains Developed on Femoral Component and Bone: A Finite Element Analysis

PubMed Central

Theodorou, E.G; Provatidis, C.G; Babis, G.C; Georgiou, C.S; Megas, P.D

2011-01-01

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost’s law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used. PMID:21792381

Large diameter femoral heads impose significant alterations on the strains developed on femoral component and bone: a finite element analysis.

PubMed

Theodorou, E G; Provatidis, C G; Babis, G C; Georgiou, C S; Megas, P D

2011-01-01

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost's law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used.

Apatite layer growth on glassy Zr48Cu36Al8Ag8 sputtered titanium for potential biomedical applications

NASA Astrophysics Data System (ADS)

Thanka Rajan, S.; Karthika, M.; Bendavid, Avi; Subramanian, B.

2016-04-01

The bioactivity of magnetron sputtered thin film metallic glasses (TFMGs) of Zr48Cu36Al8Ag8 (at.%) on titanium substrates was tested for bio implant applications. The structural and elemental compositions of TFMGs were analyzed by XRD, XPS and EDAX. X-ray diffraction analysis displayed a broad hump around the incident angle of 30-50°, suggesting that the coatings possess a glassy structure. An in situ crystal growth of hydroxyapatite was observed by soaking the sputtered specimen in simulated body fluid (SBF). The nucleation and growth of a calcium phosphate (Ca-P) bone-like hydroxyapatite on Zr48Cu36Al8Ag8 (at.%) TFMG from SBF was investigated by using XRD, AFM and SEM. The presence of calcium and phosphorus elements was confirmed by EDAX and XPS. In vitro electrochemical corrosion studies indicated that the Zr-based TFMG coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate and electrochemical stability than the bare crystalline titanium substrate.

The response of macrophages to titanium particles is determined by macrophage polarization.

PubMed

Pajarinen, Jukka; Kouri, Vesa-Petteri; Jämsen, Eemeli; Li, Tian-Fang; Mandelin, Jami; Konttinen, Yrjö T

2013-11-01

Aseptic loosening of total joint replacements is driven by the reaction of macrophages to foreign body particles released from the implant. It was hypothesized that the macrophages' response to these particles is dependent, in addition to particle characteristics and contaminating biomolecules, on the state of macrophage polarization as determined by the local cytokine microenvironment. To test this hypothesis we differentiated M1 and M2 macrophages from human peripheral blood monocytes and compared their responses to titanium particles using genome-wide microarray analysis and a multiplex cytokine assay. In comparison to non-activated M0 macrophages, the overall chemotactic and inflammatory responses to titanium particles were greatly enhanced in M1 macrophages and effectively suppressed in M2 macrophages. In addition, the genome-wide approach revealed several novel, potentially osteolytic, particle-induced mediators, and signaling pathway analysis suggested the involvement of toll-like and nod-like receptor signaling in particle recognition. It is concluded that the magnitude of foreign body reaction caused by titanium particles is dependent on the state of macrophage polarization. Thus, by limiting the action of M1 polarizing factors, e.g. bacterial biofilm formation, in peri-implant tissues and promoting M2 macrophage polarization by biomaterial solutions or pharmacologically, it might be possible to restrict wear-particle-induced inflammation and osteolysis. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Porous titanium obtained by a new powder metallurgy technique: Preliminary results of human osteoblast adhesion on surface polished substrates.

PubMed

Biasotto, M; Ricceri, R; Scuor, N; Schmid, C; Sandrucci, M A; Di Lenarda, R; Matteazzi, P

2003-01-01

This study concerns a novel powder metallurgy method for producing porous titanium (pTi) exhibiting high mechanical properties. The preparation procedure consisted of the following stages: first, the preparation of Ti and titanium hydride (TiH2) powder mixtures and their consolidation with a cold isostatic press, followed by a sintering of the green bodies performed with hot isostatic press (HIP) equipment. Thermal decomposition in controlled environment of the TiH2 phase results in the foam structure. The resulting porosity percolates with a volume fraction of approximately 20%. The final material exhibits interesting mechanical properties, comparable to those of full density titanium (between grade 2 and grade 3), with the advantage of a minor density. The samples produced were tested to verify their biological response by studying the effectiveness of osteoblast adhesion and growth. In this preliminary study, osteoblastic cell morphology was investigated and compared to that observed on fully dense commercially pure titanium (Ti-cp) (ASTM, grade 3). The preliminary results were promising regarding cellular adhesion and spreading. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 172-7).

Bioengineered titanium surfaces affect the gene-expression and phenotypic response of osteoprogenitor cells derived from mouse calvarial bones.

PubMed

Isaac, J; Galtayries, A; Kizuki, T; Kokubo, T; Berda, A; Sautier, J-M

2010-09-28

This study investigated the in vitro effects of bioactive titanium surfaces on osteoblast differentiation. Three titanium substrates were tested: a commercially pure titanium (Cp Ti), an alkali- and heat-treated titanium (AH Ti), and an apatite-formed titanium (Ap Ti) generated by soaking AH Ti in a simulated body fluid. Chemical evaluation of the surface reactivity was analysed at nanometre scale by X-ray photoelectron spectroscopy (XPS), and at micrometre scale by energy dispersive X-ray microanalysis (EDX). It showed that the estimated proportion of the surface covered by adsorbed serum proteins differed between the three substrates and confirmed the bioactivity of AH Ti, illustrated by surface calcium and phosphate deposition when immersed in biological fluids. Mouse calvaria osteoblasts were cultured on the substrates for 15 days with no sign of cytotoxicity. Enzyme immunoassay and Real-Time RT-PCR were used to follow osteoblast differentiation through the production of osteocalcin (OC) and expression of several bone markers. At day 15, a significant up-regulation of Runx2, Osx, Dlx5, ALP, BSP, OC and DMP1 mRNA levels associated with an increase of OC production were observed on AH Ti and Ap Ti when compared to Cp Ti. These results suggest that bioengineered titanium has a great potential for dental applications in enhancing osseointegration.

Reducing bacteria and macrophage density on nanophase hydroxyapatite coated onto titanium surfaces without releasing pharmaceutical agents

NASA Astrophysics Data System (ADS)

Bhardwaj, Garima; Yazici, Hilal; Webster, Thomas J.

2015-04-01

Reducing bacterial density on titanium implant surfaces has been a major concern because of the increasing number of nosocomial infections. Controlling the inflammatory response post implantation has also been an important issue for medical devices due to the detrimental effects of chronic inflammation on device performance. It has recently been demonstrated that manipulating medical device surface properties including chemistry, roughness and wettability can control both infection and inflammation. Here, we synthesized nanophase (that is, materials with one dimension in the nanoscale) hydroxyapatite coatings on titanium to reduce bacterial adhesion and inflammatory responses (as measured by macrophage functions) and compared such results to bare titanium and plasma sprayed hydroxyapatite titanium coated surfaces used clinically today. This approach is a pharmaceutical-free approach to inhibit infection and inflammation due to the detrimental side effects of any drug released in the body. Here, nanophase hydroxyapatite was synthesized in sizes ranging from 110-170 nm and was subsequently coated onto titanium samples using electrophoretic deposition. Results indicated that smaller nanoscale hydroxyapatite features on titanium surfaces alone decreased bacterial attachment in the presence of gram negative (P. aeruginosa), gram positive (S. aureus) and ampicillin resistant gram-negative (E. coli) bacteria as well as were able to control inflammatory responses; properties which should lead to their further investigation for improved medical applications.

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis

PubMed Central

Georgiou, CS; Evangelou, KG; Theodorou, EG; Provatidis, CG; Megas, PD

2012-01-01

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed. PMID:23284597

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis.

PubMed

Georgiou, Cs; Evangelou, Kg; Theodorou, Eg; Provatidis, Cg; Megas, Pd

2012-01-01

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed.

Detonation nanodiamonds biofunctionalization and immobilization to titanium alloy surfaces as first steps towards medical application.

PubMed

Gonçalves, Juliana P L; Shaikh, Afnan Q; Reitzig, Manuela; Kovalenko, Daria A; Michael, Jan; Beutner, René; Cuniberti, Gianaurelio; Scharnweber, Dieter; Opitz, Jörg

2014-01-01

Due to their outstanding properties nanodiamonds are a promising nanoscale material in various applications such as microelectronics, polishing, optical monitoring, medicine and biotechnology. Beyond the typical diamond characteristics like extreme hardness or high thermal conductivity, they have additional benefits as intrinsic fluorescence due to lattice defects without photobleaching, obtained during the high pressure high temperature process. Further the carbon surface and its various functional groups in consequence of the synthesis, facilitate additional chemical and biological modification. In this work we present our recent results on chemical modification of the nanodiamond surface with phosphate groups and their electrochemically assisted immobilization on titanium-based materials to increase adhesion at biomaterial surfaces. The starting material is detonation nanodiamond, which exhibits a heterogeneous surface due to the functional groups resulting from the nitrogen-rich explosives and the subsequent purification steps after detonation synthesis. Nanodiamond surfaces are chemically homogenized before proceeding with further functionalization. Suspensions of resulting surface-modified nanodiamonds are applied to the titanium alloy surfaces and the nanodiamonds subsequently fixed by electrochemical immobilization. Titanium and its alloys have been widely used in bone and dental implants for being a metal that is biocompatible with body tissues and able to bind with adjacent bone during healing. In order to improve titanium material properties towards biomedical applications the authors aim to increase adhesion to bone material by incorporating nanodiamonds into the implant surface, namely the anodically grown titanium dioxide layer. Differently functionalized nanodiamonds are characterized by infrared spectroscopy and the modified titanium alloys surfaces by scanning and transmission electron microscopy. The process described shows an adsorption and immobilization of modified nanodiamonds on titanium; where aminosilanized nanodiamonds coupled with O-phosphorylethanolamine show a homogeneous interaction with the titanium substrate.

Electronic and Optical Properties of Titanium Nitride Bulk and Surfaces from First Principles Calculations (Postprint)

DTIC Science & Technology

2015-11-18

thickness of the film, or substrate. In this work, we report calculations for titanium nitride ( TiN ), a promising material for plasmonic applications...stoichiometric bulk TiN , as well as of the TiN (100), TiN (110), and TiN (111) outermost surfaces. Density functional theory (DFT) and many-body GW methods...and the band structure for bulk TiN were shown to be consistent with previous work. Calculated dielectric functions, plasma frequencies, reflectivity

Heat Source - Materials Interactions during Fusion Welding.

DTIC Science & Technology

1982-04-30

calcium, chromium and tungsten lines have been identified. In the titanium spectra (Figure 6), argon, titanium, aluminum, calcium and tungsten lines have...Stainless Steel," Weld J.,5(12), 1974, p. 5 4 9 -r. 3. C. B. Shaw, Jr. "Diagnostic Studies of the GTAW Arc," Weld J. 54(2), p.33-s. 4. J. F. Key, M. E...black body radiation curve. The diagram is valid only in the manganese m.p.-b.p. range. Fig.-8 Chromium isopleths plotted against log of pressure, log

Modification of electrochemically deposited apatite using supercritical water.

PubMed

Ban, S; Hasegawa, J

2001-12-01

Supercritical water was used as a modification method of electrochemically deposited apatite on pure titanium. The apatites were coated on a commercially pure titanium plate using a hydrothermal-electrochemical method. A constant direct current at 12.5 mA/cm2 was loaded for 1 hr at 25, 60, 100, 150 and 200 degrees C in an electrolyte containing calcium and phosphate ions. The deposited apatite on the titanium substrate was stored in supercritical water at 450 degrees C under 45 MPa for 8 hr. With this treatment, the crystallinity of the apatites increased, sharp edges of the deposited apatites were rounded off, and the bonding strength of the titanium substrate to the deposited apatites significantly increased. On the other hand, weight loss in 0.01 N HCl decreased and the weight gain rate in a simulated body fluid also decreased with this treatment. It is suggested that the modification using supercritical water improved the mechanical strength of the deposited apatite, but worsened its bioactivity.

Intraoperative pulmonary embolism of Harrington rod during spinal surgery: the potential dangers of rod cutting.

PubMed

Aylott, Caspar E W; Hassan, Kamran; McNally, Donal; Webb, John K

2006-12-01

This is a case report and laboratory-based biomechanics study. The objective is to report the first case of Titanium rod embolisation during scoliosis surgery into the Pulmonary artery. To investigate the potential of an unconstrained cut Titanium rod fragment to cause wounding with reference to recognised weapons. Embolisation of a foreign body to the heart is rare. Bullet embolisation to the heart and lungs is infrequently reported in the last 80 years. Iatrogenic cases of foreign body embolisation are very rare. Fifty 1-2 cm segments of Titanium rod were cut in an unconstrained manner and a novel method was used to calculate velocity. A high-speed camera (6,000 frames/s) was used to further measure velocity and study projectile motion. The wounding potential was investigated using lambs liver, high-speed photography and local dissection. Rod velocities were measured in excess of 23 m s(-1). Rods were seen to tumble end-over-end with a maximum speed of 560 revolutions/s. The maximum kinetic energy was 0.61 J which is approximately 2% that of a crossbow. This is sufficient to cause significant liver damage. The degree of surface damage and internal disruption was influenced by the orientation of the rod fragment at impact. An unconstrained cut segment of a Titanium rod has a significant potential to wound. Precautions should be taken to avoid this potentially disastrous but preventable complication.

Toward the Modularization of Decision Support Systems

NASA Astrophysics Data System (ADS)

Raskin, R. G.

2009-12-01

Decision support systems are typically developed entirely from scratch without the use of modular components. This “stovepiped” approach is inefficient and costly because it prevents a developer from leveraging the data, models, tools, and services of other developers. Even when a decision support component is made available, it is difficult to know what problem it solves, how it relates to other components, or even that the component exists, The Spatial Decision Support (SDS) Consortium was formed in 2008 to organize the body of knowledge in SDS within a common portal. The portal identifies the canonical steps in the decision process and enables decision support components to be registered, categorized, and searched. This presentation describes how a decision support system can be assembled from modular models, data, tools and services, based on the needs of the Earth science application.

Characterization of poly(Sodium Styrene Sulfonate) Thin Films Grafted from Functionalized Titanium Surfaces

PubMed Central

Zorn, Gilad; Baio, Joe E.; Weidner, Tobias; Migonney, Veronique; Castner, David G.

2011-01-01

Biointegration of titanium implants in the body is controlled by their surface properties. Improving surface properties by coating with a bioactive polymer is a promising approach to improve the biological performance of titanium implants. To optimize the grafting processes, it is important to fully understand the composition and structure of the modified surfaces. The main focus of this study is to provide a detailed, multi-technique characterization of a bioactive poly(sodium styrene sulfonate) (pNaSS) thin film grafted from titanium surfaces via a two-step procedure. Thin titanium films (~50 nm thick with an average surface roughness of 0.9±0.2nm) prepared by evaporation onto silicon wafers were used as smooth model substrates. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed that the titanium film was covered with a TiO2 layer that was at least 10nm thick and contained hydroxyl groups present at the outermost surface. These hydroxyl groups were first modified with a 3-methacryloxypropyltrimethoxysilane (MPS) cross linker. XPS and ToF-SIMS showed that a monolayer of the MPS molecules were successfully attached onto the titanium surfaces. The pNaSS film was grafted from the MPS modified titanium through atom transfer radical polymerization. Again, XPS and ToF-SIMS were used to verify that the pNaSS molecules were successfully grafted onto the modified surfaces. Atomic force microscopy analysis showed that the film was smooth and uniformly covered the surface. Fourier transform infrared spectroscopy indicated an ordered array of grafted NaSS molecules were present on the titanium surfaces. Sum frequency generation vibration spectroscopy and near edge X-ray absorption fine structure spectroscopy illustrated that the NaSS molecules were grafted onto the titanium surface with a substantial degree of orientational order in the styrene rings. PMID:21892821

Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus

NASA Astrophysics Data System (ADS)

Cao, Huiliang; Qin, Hui; Zhao, Yaochao; Jin, Guodong; Lu, Tao; Meng, Fanhao; Zhang, Xianlong; Liu, Xuanyong

2016-02-01

Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices.

Titanium wound chambers for wound healing research.

PubMed

Nuutila, Kristo; Singh, Mansher; Kruse, Carla; Philip, Justin; Caterson, Edward J; Eriksson, Elof

2016-11-01

Standardized and reproducible animal models are crucial in medical research. Rodents are commonly used in wound healing studies since, they are easily available, affordable and simple to handle and house. However, the most significant limitation of rodent models is that the wounds heal by contraction while in humans the primary mechanisms of healing are reepithelialization and granulation tissue formation. The robust contraction results in faster wound closure that complicates the reproducibility of rodent studies in clinical trials. We have developed a titanium wound chamber for rodent wound healing research. The chamber is engineered from two pieces of titanium and is placed transcutaneously on the dorsum of a rodent. The chamber inhibits wound contraction and provides a means for controlled monitoring and sampling of the wound environment in vivo with minimal foreign body reaction. This technical report introduces two modalities utilizing the titanium chambers in rats: (1) Wound in a skin island model and, (2) Wound without skin model. Here, we demonstrate in rats how the "wound in a skin island model" slows down wound contraction and how the "wound without skin" model completely prevents the closure. The titanium wound chamber provides a reproducible standardized models for wound healing research in rodents. © 2016 by the Wound Healing Society.

Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus

PubMed Central

Cao, Huiliang; Qin, Hui; Zhao, Yaochao; Jin, Guodong; Lu, Tao; Meng, Fanhao; Zhang, Xianlong; Liu, Xuanyong

2016-01-01

Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices. PMID:26899567

Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus.

PubMed

Cao, Huiliang; Qin, Hui; Zhao, Yaochao; Jin, Guodong; Lu, Tao; Meng, Fanhao; Zhang, Xianlong; Liu, Xuanyong

2016-02-22

Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices.

Exhibit D modular design attitude control system study

NASA Technical Reports Server (NTRS)

Chichester, F.

1984-01-01

A dynamically equivalent four body approximation of the NASTRAN finite element model supplied for hybrid deployable truss to support the digital computer simulation of the ten body model of the flexible space platform that incorporates the four body truss model were investigated. Coefficients for sensitivity of state variables of the linearized model of the three axes rotational dynamics of the prototype flexible spacecraft were generated with respect to the model's parameters. Software changes required to accommodate addition of another rigid body to the five body model of the rotational dynamics of the prototype flexible spacecraft were evaluated.

Fabrication, characterization, and in vitro study of zinc substituted hydroxyapatite/silk fibroin composite coatings on titanium for biomedical applications.

PubMed

Zhong, Zhenyu; Ma, Jun

2017-09-01

Zinc substituted hydroxyapatite/silk fibroin composite coatings were deposited on titanium substrates at room temperature by electrophoretic deposition. Microscopic characterization of the synthesized composite nanoparticles revealed that the particle size ranged 50-200 nm, which increased a little after zinc substitution. The obtained coatings maintained the phase of hydroxyapatite and they could induce fast apatite formation in simulated body fluid, indicating high bone activity. The cell culturing results showed that the biomimetic hydroxyapatite coatings could regulate adhesion, spreading, and proliferation of osteoblastic cells. Furthermore, the biological behavior of the zinc substituted hydroxyapatite coatings was found to be better than the bare titanium without coatings and hydroxyapatite coatings without zinc, increasing MC3T1-E1 cell differentiation in alkaline phosphatase expression.

Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

NASA Astrophysics Data System (ADS)

Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

2017-03-01

Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

iBodies: Modular Synthetic Antibody Mimetics Based on Hydrophilic Polymers Decorated with Functional Moieties

PubMed Central

Šácha, Pavel; Knedlík, Tomáš; Schimer, Jiří; Tykvart, Jan; Parolek, Jan; Navrátil, Václav; Dvořáková, Petra; Sedlák, František; Ulbrich, Karel; Strohalm, Jiří; Majer, Pavel

2016-01-01

Abstract Antibodies are indispensable tools for biomedicine and anticancer therapy. Nevertheless, their use is compromised by high production costs, limited stability, and difficulty of chemical modification. The design and preparation of synthetic polymer conjugates capable of replacing antibodies in biomedical applications such as ELISA, flow cytometry, immunocytochemistry, and immunoprecipitation is reported. The conjugates, named “iBodies”, consist of an HPMA copolymer decorated with low‐molecular‐weight compounds that function as targeting ligands, affinity anchors, and imaging probes. We prepared specific conjugates targeting several proteins with known ligands and used these iBodies for enzyme inhibition, protein isolation, immobilization, quantification, and live‐cell imaging. Our data indicate that this highly modular and versatile polymer system can be used to produce inexpensive and stable antibody substitutes directed toward virtually any protein of interest with a known ligand. PMID:26749427

Reconstruction of Midface and Orbital Wall Defects After Maxillectomy and Orbital Content Preservation With Titanium Mesh and Fascia Lata: 3-Year Follow-Up.

PubMed

Motiee-Langroudi, Maziar; Harirchi, Iraj; Amali, Amin; Jafari, Mehrdad

2015-12-01

To describe the authors' experience in the reconstruction of patients after total maxillectomy with preservation of orbital contents for maxillary tumors using titanium mesh and autogenous fascia lata, where no setting for free flap reconstruction is available. Twelve consecutive patients with paranasal sinus tumors underwent total maxillectomy without orbital exenterations and primary reconstruction. The defects were reconstructed by titanium mesh in combination with autogenous fascia lata in the orbital floor performed by 1 surgical team. Titanium mesh (0.2 mm thick) was contoured and fixed to reconstruct the orbital floor and obtain midface projection. Fascia lata was used to cover the titanium mesh along the orbital floor to prevent fat entrapment in the mesh holes. The most common pathology was squamous cell carcinoma (50%). Patients' mean age was 45.66 years (33 to 74 yr). The mean follow-up period was 35.2 months (30 to 49 months). During follow-up, no infection or foreign body reaction was encountered. Extrusion of titanium mesh occurred in 4 patients who underwent postoperative radiotherapy. Two cases of mild diplopia at extreme gaze occurred early during the postoperative period that resolved after a few months. Placing fascia lata between the titanium mesh surface of the orbital implant and the orbital contents was successful in preventing long-term diplopia or dystopia. Nevertheless, exposure of the titanium implant through the skin surface represented a complication of this technique in 25% of patients. Further studies are required with head-to-head comparisons of artificial materials and free flaps for reconstruction of maxillectomy defects. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

On the passive and semiconducting behavior of severely deformed pure titanium in Ringer's physiological solution at 37°C: A trial of the point defect model.

PubMed

Ansari, Ghazaleh; Fattah-Alhosseini, Arash

2017-06-01

The effects of sever plastic deformation through multi-pass accumulative roll bonding on the passive and semiconducting behavior of pure titanium is evaluated in Ringer's physiological solution at 37°C in the present paper. Produced results by polarization plots and electrochemical impedance spectroscopy measurements revealed a significant advance in the passive response of the nano-grained sample compared to that of the annealed pure titanium. Also, Mott-Schottky test results of the nano-grained pure titanium represented a lower donor density and reduced flat-band potential in the formed passive film in comparison with the annealed sample. Moreover, based on the Mott-Schottky analysis in conjunction with the point defect model, it was suggested that with increase in formation potential, the calculated donor density of both annealed and nano-grained samples decreases exponentially and the thickness of the passive film linearly increases. These observations were consistent with the point defect model predictions, considering that the point defects within the passive film are metal interstitials, oxygen vacancies, or both. From the viewpoint of passive and semiconducting behavior, nano-grained pure titanium appeared to be more suitable for implant applications in simulate human body environment compared to annealed pure titanium. Copyright © 2017 Elsevier B.V. All rights reserved.

Composite Agency: Semiotics of Modularity and Guiding Interactions.

PubMed

Sharov, Alexei A

2017-07-01

Principles of constructivism are used here to explore how organisms develop tools, subagents, scaffolds, signs, and adaptations. Here I discuss reasons why organisms have composite nature and include diverse subagents that interact in partially cooperating and partially conflicting ways. Such modularity is necessary for efficient and robust functionality, including mutual construction and adaptability at various time scales. Subagents interact via material and semiotic relations, some of which force or prescribe actions of partners. Other interactions, which I call "guiding", do not have immediate effects and do not disrupt the evolution and learning capacity of partner agents. However, they modify the extent of learning and evolutionary possibilities of partners via establishment of scaffolds and constraints. As a result, subagents construct reciprocal scaffolding for each other to rebalance their communal evolution and learning. As an example, I discuss guiding interactions between the body and mind of animals, where the pain system adjusts mind-based learning to the physical and physiological constraints of the body. Reciprocal effects of mind and behaviors on the development and evolution of the body includes the effects of Lamarck and Baldwin.

Design of Modular, Shape-transitioning Inlets for a Conical Hypersonic Vehicle

NASA Technical Reports Server (NTRS)

Gollan, Rowan J.; Smart, Michael K.

2010-01-01

For a hypersonic vehicle, propelled by scramjet engines, integration of the engines and airframe is highly desirable. Thus, the forward capture shape of the engine inlet should conform to the vehicle body shape. Furthermore, the use of modular engines places a constraint on the shape of the inlet sidewalls. Finally, one may desire a combustor cross- section shape that is different from that of the inlet. These shape constraints for the inlet can be accommodated by employing a streamline-tracing and lofting technique. This design technique was developed by Smart for inlets with a rectangular-to-elliptical shape transition. In this paper, we generalise that technique to produce inlets that conform to arbitrary shape requirements. As an example, we show the design of a body-integrated hypersonic inlet on a winged-cone vehicle, typical of what might be used in a three-stage orbital launch system. The special challenge of inlet design for this conical vehicle at an angle-of-attack is also discussed. That challenge is that the bow shock sits relatively close to the vehicle body.

Pushability and frictional characteristics of medical instruments.

PubMed

Wünsche, P; Werner, C; Bloss, P

2002-01-01

A tensile testing equipment is combined with a torque module and a 3D force tranducer to characterize the pushability of catheter systems inside modular vessel phantoms. The modular construction of the phantom allows using two dimensional vessel shapes with different contours. Inside the phantom we put a tube or a guide catheter in which the instruments are pushed or redrawn in the presence of a liquid (water, blood, etc.) at body temperature. During pushing or redrawing we measure axial and rotational values. Additionally, friction forces and coefficients are separately determined by using a special designed friction module. First results are presented and discussed.

JPRS Report, Science and Technology, Europe.

DTIC Science & Technology

1991-02-15

VIDP furnace is a further development of the conventional vacuum induction melter (VIM). It has an independent smelting and processing unit, to...which various casting systems can be linked according to the modular principle. Unlike the conventional vacuum induction melter, the VIDP furnace does... induction coil and the crucible. The furnace body can be extracted for relining or replacement with another, ready-lined, fur- nace body. This

Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium.

PubMed

Amin Yavari, S; Chai, Y C; Böttger, A J; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

2015-06-01

Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20V anodizing time: 30min to 3h) are used for anodizing porous titanium structures that were later heat treated at 500°C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500°C improve the cell culture response of porous titanium. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydroxyapatite crystals biologically inspired on titanium by using an organic template based on the copolymer of acrylic acid and itaconic acid.

PubMed

Zhang, Chao; Li, Zhi-An; Cheng, Xiang-Rong; Xiao, Qun; Li, Hong-Bo

2010-01-01

Hydroxyapatite coating on metal implants is an effective method to enhance bioactive properties of the metal surface. We report here a method to coat the Ti-6Al-4V alloy with hydroxyapatite crystals. After alkaline/heat treatment, the spontaneous growth of organoapatite on titanium alloy surface involves sequential preadsorption of titanium isopropoxide (TIPO) and the copolymer of acrylic acid and itaconic acid on the metal, followed by exposure to simulated body fluid (SBF). The organoapatite characterization of the coating was carried out by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. The copolymer of acrylic acid and itaconic acid overlayer which is rich of carboxylate groups can lead to the deposition of needle-like and homogeneous HA on the surface after immersion in SBF.

Development of a new biodegradable operative clip made of a magnesium alloy: Evaluation of its safety and tolerability for canine cholecystectomy.

PubMed

Yoshida, Toshihiko; Fukumoto, Takumi; Urade, Takeshi; Kido, Masahiro; Toyama, Hirochika; Asari, Sadaki; Ajiki, Tetsuo; Ikeo, Naoko; Mukai, Toshiji; Ku, Yonson

2017-06-01

Operative clips used to ligate vessels in abdominal operation usually are made of titanium. They remain in the body permanently and form metallic artifacts in computed tomography images, which impair accurate diagnosis. Although biodegradable magnesium instruments have been developed in other fields, the physical properties necessary for operative clips differ from those of other instruments. We developed a biodegradable magnesium-zinc-calcium alloy clip with good biologic compatibility and enough clamping capability as an operative clip. In this study, we verified the safety and tolerability of this clip for use in canine cholecystectomy. Nine female beagles were used. We performed cholecystectomy and ligated the cystic duct by magnesium alloy or titanium clips. The chronologic change of clips and artifact formation were compared at 1, 4, 12, 18, and 24 weeks postoperative by computed tomography. The animals were killed at the end of the observation period, and the clips were removed to evaluate their biodegradability. We also evaluated their effect on the living body by blood biochemistry data. The magnesium alloy clip formed much fewer artifacts than the titanium clip, and it was almost absorbed at 6 months postoperative. There were no postoperative complications and no elevation of constituent elements such as magnesium, calcium, and zinc during the observation period in both groups. The novel magnesium alloy clip demonstrated sufficient sealing capability for the cystic duct and proper biodegradability in canine models. The magnesium alloy clip revealed much fewer metallic artifacts in CT than the conventional titanium clip. Copyright © 2016 Elsevier Inc. All rights reserved.

Cadaveric verification of the Eclipse AAA algorithm for spine SBRT treatments with titanium hardware.

PubMed

Grams, Michael P; Fong de Los Santos, Luis E; Antolak, John A; Brinkmann, Debra H; Clarke, Michelle J; Park, Sean S; Olivier, Kenneth R; Whitaker, Thomas J

2016-01-01

To assess the accuracy of the Eclipse Analytical Anisotropic Algorithm when calculating dose for spine stereotactic body radiation therapy treatments involving surgically implanted titanium hardware. A human spine was removed from a cadaver, cut sagittally along the midline, and then separated into thoracic and lumbar sections. The thoracic section was implanted with titanium stabilization hardware; the lumbar section was not implanted. Spine sections were secured in a water phantom and simulated for treatment planning using both standard and extended computed tomography (CT) scales. Target volumes were created on both spine sections. Dose calculations were performed using (1) the standard CT scale with relative electron density (RED) override of image artifacts and hardware, (2) the extended CT scale with RED override of image artifacts only, and (3) the standard CT scale with no RED overrides for hardware or artifacts. Plans were delivered with volumetric modulated arc therapy using a 6-MV beam with and without a flattening filter. A total of 3 measurements for each plan were made with Gafchromic film placed between the spine sections and compared with Eclipse dose calculations using gamma analysis with a 2%/2 mm passing criteria. A single measurement in a homogeneous phantom was made for each plan before actual delivery. Gamma passing rates for measurements in the homogeneous phantom were 99.6% or greater. Passing rates for measurements made in the lumbar spine section without hardware were 99.3% or greater; measurements made in the thoracic spine containing titanium were 98.6 to 99.5%. Eclipse Analytical Anisotropic Algorithm can adequately model the effects of titanium implants for spine stereotactic body radiation therapy treatments using volumetric modulated arc therapy. Calculations with standard or extended CT scales give similarly accurate results. Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Titanium as a biomaterial for ossicular replacement: results after implantation in the middle ear of the rabbit.

PubMed

Schwager, K

1998-01-01

The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube and, hence, its greater exposure to infectious agents. In this study, the biocompatability of titanium was examined in the middle ear of rabbits by using light and scanning electron microscopy. Implants were placed as middle ear prostheses or as free implants. These were inspected at 28 days, 84 days, 168 days, 336 days and 504 days following implantation for mucosal coverage, percent epithelization and any sign of foreign-body reaction. After 28 days, the prostheses were covered by regular mucosa. Although a majority of the free implants took up to 336 days for complete epithelialization, some of the free implants were not epithelialized even at day 504. There were no inflammatory cells observed on the surface of the material, nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. The results of this animal experiment indicate that titanium is a favorable material for ossicular replacement prostheses.

Modified titanium implant as a gateway to the human body: the implant mediated drug delivery system.

PubMed

Park, Young-Seok; Cho, Joo-Youn; Lee, Shin-Jae; Hwang, Chee Il

2014-01-01

The aim of this study was to investigate the efficacy of a proposed new implant mediated drug delivery system (IMDDS) in rabbits. The drug delivery system is applied through a modified titanium implant that is configured to be implanted into bone. The implant is hollow and has multiple microholes that can continuously deliver therapeutic agents into the systematic body. To examine the efficacy and feasibility of the IMDDS, we investigated the pharmacokinetic behavior of dexamethasone in plasma after a single dose was delivered via the modified implant placed in the rabbit tibia. After measuring the plasma concentration, the areas under the curve showed that the IMDDS provided a sustained release for a relatively long period. The result suggests that the IMDDS can deliver a sustained release of certain drug components with a high bioavailability. Accordingly, the IMDDS may provide the basis for a novel approach to treating patients with chronic diseases.

Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

PubMed

Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

2017-10-14

Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanical and histological analysis of bone-pedicle screw interface in vivo: titanium versus stainless steel.

PubMed

Sun, C; Huang, G; Christensen, F B; Dalstra, M; Overgaard, S; Bünger, C

1999-05-01

To investigate the differences in bone interface between titanium and stainless steel pedicle screws in the lumbar spine. Eighteen adult mini-pigs that underwent total laminectomy, posterolateral spinal fusion (L4-L5) were randomly selected to receive stainless steel (9) or titanium pedicle screw devices (9). In both groups, the devices were CCD (Sofamore Danek) type with the same size and shape. The postoperative observation time was 3 months. Screws from L4 were harvested along their long axis of pedicle for histomorphometric study. Bone-screw interface and bone volume from thread were examined using linear intercept techniques. Mechanical testing (torsional test and pull-out test) was performed on the screws from L5. The titanium screw group had a significantly higher maximum torque (P < 0.05) and angle related stiffness (P < 0.05) measured by torsional test. In the pull-out tests, no differences were found between the two groups in relation to the maximum load, stiffness and energy to failure. Direct bone contact with the screw in percentage was 29.4% for stainless steel and 43.8% for titanium (P < 0.05). No differences in the bone purchase between the vertebral body part and pedicle part were found. Pedicle screws made of titanium have a better bone-screw interface binding than screws made of stainless steel. Torsional tests are more informative for bone-screw interface study. Pull-out tests seem less valuable when comparing bone purchase of screws made from different materials.

Influence of microstructure and chemical composition of sputter deposited TiO2 thin films on in vitro bioactivity.

PubMed

Lilja, Mirjam; Genvad, Axel; Astrand, Maria; Strømme, Maria; Enqvist, Håkan

2011-12-01

Functionalisation of biomedical implants via surface modifications for tailored tissue response is a growing field of research. Crystalline TiO(2) has been proven to be a bone bioactive, non-resorbable material. In contact with body fluids a hydroxyapaptite (HA) layer forms on its surface facilitating the bone contact. Thus, the path of improving biomedical implants via deposition of crystalline TiO(2) on the surface is interesting to follow. In this study we have evaluated the influence of microstructure and chemical composition of sputter deposited titanium oxide thin films on the in vitro bioactivity. We find that both substrate bias, topography and the flow ratio of the gases used during sputtering affect the HA layer formed on the films after immersion in simulated body fluid at 37°C. A random distribution of anatase and rutile crystals, formed at negative substrate bias and low Ar to O(2) gas flow ratios, are shown to favor the growth of flat HA crystal structures whereas higher flow ratios and positive substrate bias induced growth of more spherical HA structures. These findings should provide valuable information when optimizing the bioactivity of titanium oxide coatings as well as for tailoring process parameters for sputtered-based production of bioactive titanium oxide implant surfaces.

Screw fixation of the syndesmosis: a cadaver model comparing stainless steel and titanium screws and three and four cortical fixation.

PubMed

Beumer, Annechien; Campo, Martin M; Niesing, Ruud; Day, Judd; Kleinrensink, Gert-Jan; Swierstra, Bart A

2005-01-01

We assessed syndesmotic set screw strength and fixation capacity during cyclical testing in a cadaver model simulating protected weight bearing. Sixteen fresh frozen legs with artificial syndesmotic injuries and a syndesmotic set screw made of stainless steel or titanium, inserted through three or four cortices, were axially loaded with 800 N for 225,000 cycles in a materials testing machine. The 225,000 cycles equals the number of paces taken by a person walking in a below knee plaster during 9 weeks. Syndesmotic fixation failure was defined as: bone fracture, screw fatigue failure, screw pullout, and/or excessive syndesmotic widening. None of the 14 out of 16 successfully tested legs or screws failed. No difference was found in fixation of the syndesmosis when stainless steel screws were compared to titanium screws through three or four cortices. Mean lateral displacement found after testing was 1.05 mm (S.D. = 0.42). This increase in tibiofibular width exceeds values described in literature for the intact syndesmosis loaded with body weight. Based on this laboratory study it is concluded that the syndesmotic set screw cannot prevent excessive syndesmotic widening when loaded with a load comparable with body weight. Therefore, we advise that patients with a syndesmotic set screw in situ should not bear weight.

Titanium α-ω phase transformation pathway and a predicted metastable structure

DOE PAGES

Zarkevich, Nickolai A.; Johnson, Duane D.

2016-01-15

A titanium is a highly utilized metal for structural lightweighting and its phases, transformation pathways (transition states), and structures have scientific and industrial importance. Using a proper solid-state nudged elastic band method employing two climbing images combined with density functional theory DFT + U methods for accurate energetics, we detail the pressure-induced α (ductile) to ω (brittle) transformation at the coexistence pressure. We also find two transition states along the minimal-enthalpy path and discover a metastable body-centered orthorhombic structure, with stable phonons, a lower density than the end-point phases, and decreasing stability with increasing pressure.

Anterior facetal realignment and distraction for atlanto-axial subluxation with basilar invagination …. a technical note.

PubMed

Patkar, Sushil

2016-08-01

Unilateral anterior retropharyngeal approach was used in a case of basilar invagination with atlanto-axial instability. This approach provided easy access to both atlanto-axial joints. Wedge-shaped titanium cages were used to distract the joints and reduce the basilar invagination. Titanium plates with screws were used to fix the lateral mass of atlas with the body of axis, bilaterally. The anterior atlanto-axial joint distraction procedure has not been described in literature before seems to be an easy option in selected cases of craniovertebral anomalies and needs to be investigated by more surgeons.

Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

DOEpatents

Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

2016-04-12

A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

[Effect of surface modification using laser on wear resistance of titanium].

PubMed

Sato, Yohei

2005-02-01

Severe wear of cast commercial pure (CP) titanium teeth was observed in a clinical survey. This study evaluated the wear resistance of cast CP titanium and titanium alloy teeth after the surface was modified using laser technology. Teeth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan). All teeth specimens were cast with CP Ti grade 3 (T-Alloy H, GC) and Ti-6Al-7Nb (T-Alloy Tough, GC). After the occlusal surface was blasted with Al(2)O(3), the occlusal contact points were modified using a laser (Neo laser L, Girrbach, Germany) at the following irradiation conditions (voltage: 260 V; pulse: 7 ms; focus: 1.5 mm). These parameters were determined by preliminary study. As a control, Type IV gold alloy (PGA-3, Ishifuku, Japan) was also cast conventionally. Both maxillary and mandibular teeth were worn using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Scheffé's test (alpha=0.05). The gold alloy showed the best wear resistance of all the metals tested. Of all the titanium specimens tested, the modified surface indicated significantly greater wear resistance than did conventional titanium teeth without surface modification (p<0.05). Wear resistance was increased by modification of the surface using a laser. If severe wear of titanium teeth was observed clinically, little wear occurred when the occlusal facets were irradiated using a laser.

Histologic study of periprosthetic osteolytic lesions after AES total ankle replacement. A 22 case series.

PubMed

Dalat, F; Barnoud, R; Fessy, M-H; Besse, J-L

2013-10-01

Medium-term results for total ankle replacement (TAR) are in general satisfactory, but there is a high redo rate for periprosthetic osteolysis associated with the AES implant. Comparing radioclinical findings and histologic analysis of implant revision procedure specimens can account for the elevated rate of osteolysis associated with the AES TAR implant. In a prospective series of 84 AES TAR implants (2003-2008), 25 underwent revision for osteolysis (including three undergoing revision twice) at a mean 59.8 months. Eight patients had hydroxyapatite (HA) coated models and the others had titanium-hydroxyapatite (Ti-HA) coatings. Radiographs were systematically analyzed on Besse's protocol and evolution was monitored on AOFAS scores. The 94 specimens taken for histologic analysis during revision were re-examined, focusing specifically on foreign bodies. Macroscopically, no metallosis or polyethylene wear was found at revision. AOFAS global and pain scores fell respectively from 89.7/100 at 1 year postoperatively to 72.9 before revision and from 32.5/40 to 20.6/40, although global scores were unchanged in 25% of patients. Radiologically, all patients showed tibial and talar osteolytic lesions, 45% showed cortical lysis and in 25% the implant had collapsed into the cysts. All specimens showed macrophagic granulomatous inflammatory reactions in contact with a foreign body; the cysts showed necrotic remodeling. Some of the foreign bodies could be identified on optical histologic examination with polyethylene in 95% of the specimens and metal in 60% (100% of HA-coated models and 33.3% of Ti-HA-coated models). Unidentifiable material was associated: a brownish pigment in Ti-HA-coated models (33.3%) and flakey bodies in 44.4% of the HA-coated models and 18.2% of the Ti-HA-coated models. The phenomenon of periprosthetic osteolysis is still poorly understood, although implant wear debris seems to be implicated. All the patients with HA-coated implants with modular tibial stem had metal particles in the tissue around the implant, although their exact nature could not be determined. The double-layer Ti-HA coating may induce delamination by fretting while the biological bone anchorage is forming. Prospective cohort study - Level IV. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Controlled release of chlorhexidine antiseptic from microporous amorphous silica applied in open porosity of an implant surface.

PubMed

Verraedt, Els; Braem, Annabel; Chaudhari, Amol; Thevissen, Karin; Adams, Erwin; Van Mellaert, Lieve; Cammue, Bruno P A; Duyck, Joke; Anné, Jozef; Vleugels, Jef; Martens, Johan A

2011-10-31

Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive agent was applied in the open porosity of a titanium coating on a Ti-6Al-4V metal substrate. The pores of the AMS emptied by calcination were loaded with chlorhexidine diacetate (CHX) via incipient wetness impregnation with CHX solution, followed by solvent evaporation. Using this CHX loaded AMS system on titanium substrate sustained release of CHX into physiological medium was obtained over a 10 day-period. CHX released from the AMS coating was demonstrated to be effective in killing planktonic cultures of the human pathogens Candida albicans and Staphylococcus epidermidis. This surface modification of titanium bodies with AMS controlled release functionality for a bioactive compound potentially can be applied on dental and orthopaedic implants to abate implant-associated microbial infection. Copyright © 2011 Elsevier B.V. All rights reserved.

Biomimetic whisker-shaped apatite coating of titanium powder.

PubMed

Sim, Young Uk; Kim, Jong Hee; Yang, Tae Young; Yoon, Seog Young; Park, Hong Chae

2010-05-01

Biomimetic apatite coatings on chemically modified titanium powder have been processed and the resulting coating layers evaluated in terms of morphology, composition and structure, using TF-XRD, XPS, SEM, TEM and FTIR analysis. After 7 days immersion in a simulated body fluid (SBF), nanometer-sized fine precipitates with an amorphous whisker-like phase and a Ca/P atomic ratio of 1.94 were obtained on the external surface of the titanium particles. When the immersion time in SBF was extended to 16 days, the coating layer consisted of the whisker-like nanostructured crystals of carbonated hydroxyapatite with a atomic ratio of 3; in such a case, a double coating layer was developed. The double layer could be divided into two regions and could be clearly distinguished: an inner dense region (approximately 200 nm in thickness) which may include hard agglomerated crystals and an outer less dense region (> 500 nm in thickness) in which crystals are loosely distributed.

Titanium modified with layer-by-layer sol-gel tantalum oxide and an organodiphosphonic acid: a coating for hydroxyapatite growth.

PubMed

Arnould, C; Volcke, C; Lamarque, C; Thiry, P A; Delhalle, J; Mekhalif, Z

2009-08-15

Titanium and its alloys are widely used in surgical implants due to their appropriate properties like corrosion resistance, biocompatibility, and load bearing. Unfortunately when metals are used for orthopedic and dental implants there is the possibility of loosening over a long period of time. Surface modification is a good way to counter this problem. A thin tantalum oxide layer obtained by layer-by-layer (LBL) sol-gel deposition on top of a titanium surface is expected to improve biocorrosion resistance in the body fluid, biocompatibility, and radio-opacity. This elaboration step is followed by a modification of the tantalum oxide surface with an organodiphosphonic acid self-assembled monolayer, capable of chemically binding to the oxide surface, and also improving hydroxyapatite growth. The different steps of this proposed process are characterized by surfaces techniques like contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).

Insight into point defects and impurities in titanium from first principles

NASA Astrophysics Data System (ADS)

Nayak, Sanjeev K.; Hung, Cain J.; Sharma, Vinit; Alpay, S. Pamir; Dongare, Avinash M.; Brindley, William J.; Hebert, Rainer J.

2018-03-01

Titanium alloys find extensive use in the aerospace and biomedical industries due to a unique combination of strength, density, and corrosion resistance. Decades of mostly experimental research has led to a large body of knowledge of the processing-microstructure-properties linkages. But much of the existing understanding of point defects that play a significant role in the mechanical properties of titanium is based on semi-empirical rules. In this work, we present the results of a detailed self-consistent first-principles study that was developed to determine formation energies of intrinsic point defects including vacancies, self-interstitials, and extrinsic point defects, such as, interstitial and substitutional impurities/dopants. We find that most elements, regardless of size, prefer substitutional positions, but highly electronegative elements, such as C, N, O, F, S, and Cl, some of which are common impurities in Ti, occupy interstitial positions.

Optical properties of ion beam textured metals. [using copper, silicon, aluminum, titanium and stainless steels

NASA Technical Reports Server (NTRS)

Hudson, W. R.; Weigand, A. J.; Mirtich, M. J.

1977-01-01

Copper, silicon, aluminum, titanium and 316 stainless steel were textured by 1000 eV xenon ions from an 8 cm diameter electron bombardment ion source. Simultaneously sputter-deposited tantalum was used to facilitate the development of the surface microstructure. Scanning electron microscopy of the ion textured surfaces revealed two types of microstructure. Copper, silicon, and aluminum developed a cone structure with an average peak-to-peak distance ranging from 1 micron for silicon to 6 microns for aluminum. Titanium and 316 stainless steel developed a serpentine ridge structure. The average peak-to-peak distance for both of these materials was 0.5 micron. Spectral reflectance was measured using an integrating sphere and a holraum reflectometer. Total reflectance for air mass 0 and 2, solar absorptance and total emittance normalized for a 425 K black body were calculated from the reflectance measurements.

Preliminary Design of a Modular Unmanned Research Vehicle. Volume 1. System Design Document

DTIC Science & Technology

1988-12-01

providing con- munications and restraint. 1-5 Tethered unpowered vehicle - an airplane-like body tether-mounted to an automobile , the auto providing...the velocity by towing. Auto-mounted vehicle - an airplane-like body rigidly mounted external to an automobile , the auto providing the velocity. Rail...accordingly. Based on this experiment, the MURV flight control system must be flexible in two ways: it should be reprogrammable for varying experimental

Modular robot

DOEpatents

Ferrante, Todd A.

1997-01-01

A modular robot may comprise a main body having a structure defined by a plurality of stackable modules. The stackable modules may comprise a manifold, a valve module, and a control module. The manifold may comprise a top surface and a bottom surface having a plurality of fluid passages contained therein, at least one of the plurality of fluid passages terminating in a valve port located on the bottom surface of the manifold. The valve module is removably connected to the manifold and selectively fluidically connects the plurality of fluid passages contained in the manifold to a supply of pressurized fluid and to a vent. The control module is removably connected to the valve module and actuates the valve module to selectively control a flow of pressurized fluid through different ones of the plurality of fluid passages in the manifold. The manifold, valve module, and control module are mounted together in a sandwich-like manner and comprise a main body. A plurality of leg assemblies are removably connected to the main body and are removably fluidically connected to the fluid passages in the manifold so that each of the leg assemblies can be selectively actuated by the flow of pressurized fluid in different ones of the plurality of fluid passages in the manifold.

Experimental Measurement of the Static Coefficient of Friction at the Ti-Ti Taper Connection in Total Hip Arthroplasty.

PubMed

Bitter, T; Khan, I; Marriott, T; Schreurs, B W; Verdonschot, N; Janssen, D

2016-03-01

The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 - 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively.

Reconstruction of a mandibular segmental defect with a customized 3-dimensional-printed titanium prosthesis in a cat with a mandibular osteosarcoma.

PubMed

Liptak, Julius M; Thatcher, Graham P; Bray, Jonathan P

2017-04-15

CASE DESCRIPTION A 12-year-old neutered male domestic shorthair cat had been treated for a mass arising from the lingual aspect of the caudal right mandibular body. Cytoreductive surgery of the mass had been performed twice over a 2-year period, but the mass recurred following both surgeries. The mass was diagnosed as an osteosarcoma, and the cat was referred for further evaluation and treatment. CLINICAL FINDINGS Clinical findings were unremarkable, except for a 2-cm-diameter mass arising from the lingual aspect of the right mandible and mild anemia and lymphopenia. Pre- and postcontrast CT scans of the head, neck, and thorax were performed, revealing that the osteosarcoma was confined to the caudal right mandibular body, with no evidence of lymph node or pulmonary metastasis. TREATMENT AND OUTCOME The stereolithographic files of the CT scan of the head were sent for computer-aided design and manufacture of a customized 3-D-printed titanium prosthesis. Segmental mandibulectomy was performed, and the mandibular defect was reconstructed in a single stage with the 3-D-printed titanium prosthesis. The cat had 1 minor postoperative complication but had no signs of eating difficulties at any point after surgery. The cat was alive and disease free 14 months postoperatively. CLINICAL RELEVANCE Reconstruction of the mandible of a cat following mandibulectomy was possible with computer-aided design and manufacture of a customized 3-D-printed titanium prosthesis. Cats have a high rate of complications following mandibulectomy, and these initial findings suggested that mandibular reconstruction may reduce the risk of these complications and result in a better functional outcome.

Correlations between the in vitro and in vivo bioactivity of the Ti/HA composites fabricated by a powder metallurgy method.

PubMed

Ning, Congqin; Zhou, Yu

2008-11-01

Ti/HA composites were successfully prepared by a powder metallurgy method and the effect of phase composition on the in vitro and in vivo bioactivity of the Ti/HA composites was investigated in the present study. The correlations between the in vitro and in vivo biological behaviors were highlighted. The results showed that the in vitro and in vivo bioactivity of the Ti/HA composites was dependent on their phase composition. The in vitro bioactivity of the Ti/HA composites was evaluated in simulated body fluid with ion concentrations similar to those of human plasma. After immersion in the simulated body fluid for a certain time, apatite precipitations formed on the surface of the composites with an initial titanium content of 50 and 70 wt.%, and no apatite was found on the surface of the composite with 30% titanium. Ti(2)O was responsible for the apatite formation on the surfaces of the composites. For in vivo analysis, Ti/HA cylinders were implanted in the metaphases of the rabbit femur. At the early stage of implantation, the new bone formed on the surface of the composite with 30% titanium was much less than that on the surfaces of the composites with 50% and 70% titanium. All the Ti/HA composites formed a chemical bone-bonding interface with the host bone by 6 months after implantation. The Ti/HA composites formed the bone-bonding interface with the surrounding bone through an apatite layer. The results in the present study suggested that the in vivo results agreed well with the in vitro results.

Resorbable versus titanium plates for orthognathic surgery.

PubMed

Fedorowicz, Z; Nasser, M; Newton, J T; Oliver, R J

2007-04-18

Recognition of some of the limitations of titanium plates and screws used for the fixation of bones has led to the development of plates manufactured from bioresorbable materials. Whilst resorbable plates appear to offer clinical advantages over metal plates in orthognathic surgery, concerns remain about the stability of fixation and the length of time required for their degradation and the possibility of foreign body reactions. To compare the effectiveness of bioresorbable fixation systems with titanium systems used during orthognathic surgery. We searched the following databases: Cochrane Oral Health Group Trials Register (to 26th January 2006); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 4); MEDLINE (without filter) (from 1966 to 26th January 2006); and EMBASE (without filter) (from 1980 to 26th January 2006). Randomised controlled trials comparing resorbable versus titanium fixation systems used for orthognathic surgery. Clinical heterogeneity between the included trials precluded pooling of data, and only a descriptive summary is presented. This review included two trials, involving 103 participants, one compared titanium with resorbable plates and screws and the other titanium with resorbable screws, both provided very limited data for the primary outcomes of this review. All patients in one trial suffered mild to moderate postoperative discomfort with no statistically significant difference between the two plating groups at different follow-up times. Mean scores of patient satisfaction were 7.43 to 8.63 (range 0 to 10) with no statistically significant difference between the two groups throughout follow up. Adverse effects reported in one study were two plate exposures in each group occurring between the third and ninth months. Plate exposures occurred mainly in the posterior maxillary region, except for one titanium plate exposure in the mandibular premolar region. Known causes of infection were associated with loosened screws and wound dehiscence with no statistically significant difference in the infection rate between titanium (3/196), and resorbable (3/165) plates P = 0.83 (published as P = 0.67). This review provides some evidence to show that there is no statistically significant difference in postoperative discomfort, level of patient satisfaction, plate exposure or infection for plate and screw fixation using either titanium or resorbable materials in orthognathic surgery.

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages

PubMed Central

Markhoff, Jana; Krogull, Martin; Schulze, Christian; Rotsch, Christian; Hunger, Sandra; Bader, Rainer

2017-01-01

The biomaterials used to maintain or replace functions in the human body consist mainly of metals, ceramics or polymers. In orthopedic surgery, metallic materials, especially titanium and its alloys, are the most common, due to their excellent mechanical properties, corrosion resistance, and biocompatibility. Aside from the established Ti6Al4V alloy, shape memory materials such as nickel-titanium (NiTi) have risen in importance, but are also discussed because of the adverse effects of nickel ions. These might be reduced by specific surface modifications. In the present in vitro study, the osteoblastic cell line MG-63 as well as primary human osteoblasts, fibroblasts, and macrophages were cultured on titanium alloys (forged Ti6Al4V, additive manufactured Ti6Al4V, NiTi, and Diamond-Like-Carbon (DLC)-coated NiTi) to verify their specific biocompatibility and inflammatory potential. Additive manufactured Ti6Al4V and NiTi revealed the highest levels of metabolic cell activity. DLC-coated NiTi appeared as a suitable surface for cell growth, showing the highest collagen production. None of the implant materials caused a strong inflammatory response. In general, no distinct cell-specific response could be observed for the materials and surface coating used. In summary, all tested titanium alloys seem to be biologically appropriate for application in orthopedic surgery. PMID:28772412

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages.

PubMed

Markhoff, Jana; Krogull, Martin; Schulze, Christian; Rotsch, Christian; Hunger, Sandra; Bader, Rainer

2017-01-10

The biomaterials used to maintain or replace functions in the human body consist mainly of metals, ceramics or polymers. In orthopedic surgery, metallic materials, especially titanium and its alloys, are the most common, due to their excellent mechanical properties, corrosion resistance, and biocompatibility. Aside from the established Ti6Al4V alloy, shape memory materials such as nickel-titanium (NiTi) have risen in importance, but are also discussed because of the adverse effects of nickel ions. These might be reduced by specific surface modifications. In the present in vitro study, the osteoblastic cell line MG-63 as well as primary human osteoblasts, fibroblasts, and macrophages were cultured on titanium alloys (forged Ti6Al4V, additive manufactured Ti6Al4V, NiTi, and Diamond-Like-Carbon (DLC)-coated NiTi) to verify their specific biocompatibility and inflammatory potential. Additive manufactured Ti6Al4V and NiTi revealed the highest levels of metabolic cell activity. DLC-coated NiTi appeared as a suitable surface for cell growth, showing the highest collagen production. None of the implant materials caused a strong inflammatory response. In general, no distinct cell-specific response could be observed for the materials and surface coating used. In summary, all tested titanium alloys seem to be biologically appropriate for application in orthopedic surgery.

Binding of plasma proteins to titanium dioxide nanotubes with different diameters

PubMed Central

Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

2015-01-01

Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

Electrochemical surface modification of titanium in dentistry.

PubMed

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.

Biomineralized diamond-like carbon films with incorporated titanium dioxide nanoparticles improved bioactivity properties and reduced biofilm formation.

PubMed

Lopes, F S; Oliveira, J R; Milani, J; Oliveira, L D; Machado, J P B; Trava-Airoldi, V J; Lobo, A O; Marciano, F R

2017-12-01

Recently, the development of coatings to protect biomedical alloys from oxidation, passivation and to reduce the ability for a bacterial biofilm to form after implantation has emerged. Diamond-like carbon films are commonly used for implanted medical due to their physical and chemical characteristics, showing good interactions with the biological environment. However, these properties can be significantly improved when titanium dioxide nanoparticles are included, especially to enhance the bactericidal properties of the films. So far, the deposition of hydroxyapatite on the film surface has been studied in order to improve biocompatibility and bioactive behavior. Herein, we developed a new route to obtain a homogeneous and crystalline apatite coating on diamond-like carbon films grown on 304 biomedical stainless steel and evaluated its antibacterial effect. For this purpose, films containing two different concentrations of titanium dioxide (0.1 and 0.3g/L) were obtained by chemical vapor deposition. To obtain the apatite layer, the samples were soaked in simulated body fluid solution for up to 21days. The antibacterial activity of the films was evaluated by bacterial eradication tests using Staphylococcus aureus biofilm. Scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy, and goniometry showed that homogeneous, crystalline, and hydrophilic apatite films were formed independently of the titanium dioxide concentration. Interestingly, the diamond-like films containing titanium dioxide and hydroxyapatite reduced the biofilm formation compared to controls. A synergism between hydroxyapatite and titanium dioxide that provided an antimicrobial effect against opportunistic pathogens was clearly observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Osteoconductive phosphoserine-modified poly(ε-lysine) dendrons: synthesis, titanium oxide surface functionalization and response of osteoblast-like cell lines

PubMed Central

Meikle, S. T.; Bianchi, G.; Olivier, G.; Santin, M.

2013-01-01

The lack of direct bonding between the surface of an implant and the mineralized bony tissue is among the main causes of aseptic loosening in titanium-based implants. Surface etching and ceramic coatings have led to improved osteointegration, but their clinical performance is still limited either by partial bonding or by coating delamination. In this work, a solid-phase synthesis method has been optimized to produce poly(ε-lysine) dendrons, the outermost branching generation of which is functionalized by phosphoserine (PS), a known catalyst of the biomineralization process. The dendrons were deposited onto etched titanium oxide surfaces as a near-to-monolayer film able to induce the formation of a homogeneous calcium phosphate phase in a simulated body fluid over 3 days. The dendron films also stimulated MG63 and SAOS-2 osteoblast-like cells to proliferate at a rate significantly higher than etched titanium, with SAOS-2 also showing a higher degree of differentiation over 14 days. PS-tethered dendron films were not affected by various sterilization methods and UV treatment appeared to improve the cell substrate potential of these films, thus suggesting their potential as a surface functionalization method for bone implants. PMID:23193106

Electrochemical Behavior of Biomedical Titanium Alloys Coated with Diamond Carbon in Hanks' Solution

NASA Astrophysics Data System (ADS)

Gnanavel, S.; Ponnusamy, S.; Mohan, L.; Radhika, R.; Muthamizhchelvan, C.; Ramasubramanian, K.

2018-03-01

Biomedical implants in the knee and hip are frequent failures because of corrosion and stress on the joints. To solve this important problem, metal implants can be coated with diamond carbon, and this coating plays a critical role in providing an increased resistance to implants toward corrosion. In this study, we have employed diamond carbon coating over Ti-6Al-4V and Ti-13Nb-13Zr alloys using hot filament chemical vapor deposition method which is well-established coating process that significantly improves the resistance toward corrosion, wears and hardness. The diamond carbon-coated Ti-13Nb-13Zr alloy showed an increased microhardness in the range of 850 HV. Electrochemical impedance spectroscopy and polarization studies in SBF solution (simulated body fluid solution) were carried out to understand the in vitro behavior of uncoated as well as coated titanium alloys. The experimental results showed that the corrosion resistance of Ti-13Nb-13Zr alloy is relatively higher when compared with diamond carbon-coated Ti-6Al-4V alloys due to the presence of β phase in the Ti-13Nb-13Zr alloy. Electrochemical impedance results showed that the diamond carbon-coated alloys behave as an ideal capacitor in the body fluid solution. Moreover, the stability in mechanical properties during the corrosion process was maintained for diamond carbon-coated titanium alloys.

Power Efficient Hydraulic Systems. Volume 1. Study Phase

DTIC Science & Technology

1988-07-01

AIRCRAFT SUBSYSTEMS TABLE 14. Baseline aircraft systems o HYDRAULIC SYSTEM o ELECTRICAL SYSTEM o 8000 PSI, 3 INDEPENDENT SYSTEMS o HVDC POWER o APU...neither aluminum nor titanium provide good wear surfaces. Hydraulic fittings and valve bodies appear to be excellent candidates for PM technology...Actuator Bodies Savings Over Steel ys. Time of Heat and 25% Over Treatment To Be Resolved T1-3AL-2.5V - Heat Treatment May Cause - Excellent

Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces.

PubMed

Wijesinghe, W P S L; Mantilaka, M M M G P G; Chathuranga Senarathna, K G; Herath, H M T U; Premachandra, T N; Ranasinghe, C S K; Rajapakse, R P V J; Rajapakse, R M G; Edirisinghe, Mohan; Mahalingam, S; Bandara, I M C C D; Singh, Sanjleena

2016-06-01

Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. Copyright © 2016 Elsevier B.V. All rights reserved.

Lunar based massdriver applications

NASA Astrophysics Data System (ADS)

Ehresmann, Manfred; Gabrielli, Roland Atonius; Herdrich, Georg; Laufer, René

2017-05-01

The results of a lunar massdriver mission and system analysis are discussed and show a strong case for a permanent lunar settlement with a site near the lunar equator. A modular massdriver concept is introduced, which uses multiple acceleration modules to be able to launch large masses into a trajectory that is able to reach Earth. An orbital mechanics analysis concludes that the launch site will be in the Oceanus Procellarum a flat, Titanium rich lunar mare area. It is further shown that the bulk of massdriver components can be manufactured by collecting lunar minerals, which are broken down into its constituting elements. The mass to orbit transfer rates of massdriver case study are significant and can vary between 1.8 kt and 3.3 megatons per year depending on the available power. Thus a lunar massdriver would act as a catalyst for any space based activities and a game changer for the scale of feasible space projects.

Modular decomposition of metabolic reaction networks based on flux analysis and pathway projection.

PubMed

Yoon, Jeongah; Si, Yaguang; Nolan, Ryan; Lee, Kyongbum

2007-09-15

The rational decomposition of biochemical networks into sub-structures has emerged as a useful approach to study the design of these complex systems. A biochemical network is characterized by an inhomogeneous connectivity distribution, which gives rise to several organizational features, including modularity. To what extent the connectivity-based modules reflect the functional organization of the network remains to be further explored. In this work, we examine the influence of physiological perturbations on the modular organization of cellular metabolism. Modules were characterized for two model systems, liver and adipocyte primary metabolism, by applying an algorithm for top-down partition of directed graphs with non-uniform edge weights. The weights were set by the engagement of the corresponding reactions as expressed by the flux distribution. For the base case of the fasted rat liver, three modules were found, carrying out the following biochemical transformations: ketone body production, glucose synthesis and transamination. This basic organization was further modified when different flux distributions were applied that describe the liver's metabolic response to whole body inflammation. For the fully mature adipocyte, only a single module was observed, integrating all of the major pathways needed for lipid storage. Weaker levels of integration between the pathways were found for the early stages of adipocyte differentiation. Our results underscore the inhomogeneous distribution of both connectivity and connection strengths, and suggest that global activity data such as the flux distribution can be used to study the organizational flexibility of cellular metabolism. Supplementary data are available at Bioinformatics online.

Rigid spine reinforced polymer microelectrode array probe and method of fabrication

DOEpatents

Tabada, Phillipe; Pannu, Satinderpall S

2014-05-27

A rigid spine-reinforced microelectrode array probe and fabrication method. The probe includes a flexible elongated probe body with conductive lines enclosed within a polymeric material. The conductive lines connect microelectrodes found near an insertion end of the probe to respective leads at a connector end of the probe. The probe also includes a rigid spine, such as made from titanium, fixedly attached to the probe body to structurally reinforce the probe body and enable the typically flexible probe body to penetrate and be inserted into tissue, such as neural tissue. By attaching or otherwise fabricating the rigid spine to connect to only an insertion section of the probe body, an integrally connected cable section of the probe body may remain flexible.

Evaluation of a Cooling Headpiece during Work in a Hot Environment

DTIC Science & Technology

1987-10-01

Press, 1960. 3. Brown, GA, and Willims, GM: The effects of head cooling on deep body temperature and thermal comfort in man. Aviat. Space & Environ...1971. 18. Williams, BA, and Shitzer, A,. A modular liquid-cooled helmet for thermal comfort . Aerospace Med. 45(g):1030-1036, 1974. 11J i. E Appendix A...to physiological benefits, soldier comfort and performance mey I also be enhanced by the CHP. Scalp temperature may be a factor in whole body thermal

Modular design attitude control system

NASA Technical Reports Server (NTRS)

Chichester, F. D.

1982-01-01

A hybrid multilevel linear quadratic regulator (ML-LQR) approach was developed and applied to the attitude control of models of the rotational dynamics of a prototype flexible spacecraft and of a typical space platform. Three axis rigid body flexible suspension models were developed for both the spacecraft and the space platform utilizing augmented body methods. Models of the spacecraft with hybrid ML-LQR attitude control and with LQR attitude control were simulated and their response with the two different types of control were compared.

Titanium Dioxide Nanoparticles in Food and Personal Care Products

PubMed Central

Weir, Alex; Westerhoff, Paul; Fabricius, Lars

2012-01-01

Titanium dioxide is a common additive in many food, personal care, and other consumer products used by people, which after use can enter the sewage system, and subsequently enter the environment as treated effluent discharged to surface waters or biosolids applied to agricultural land, incinerated wastes, or landfill solids. This study quantifies the amount of titanium in common food products, derives estimates of human exposure to dietary (nano-) TiO2, and discusses the impact of the nanoscale fraction of TiO2 entering the environment. The foods with the highest content of TiO2 included candies, sweets and chewing gums. Among personal care products, toothpastes and select sunscreens contained 1% to >10% titanium by weight. While some other crèmes contained titanium, despite being colored white, most shampoos, deodorants, and shaving creams contained the lowest levels of titanium (<0.01 μg/mg). For several high-consumption pharmaceuticals, the titanium content ranged from below the instrument detection limit (0.0001 μg Ti/mg) to a high of 0.014 μg Ti/mg. Electron microscopy and stability testing of food-grade TiO2 (E171) suggests that approximately 36% of the particles are less than 100 nm in at least one dimension and that it readily disperses in water as fairly stable colloids. However, filtration of water solubilized consumer products and personal care products indicated that less than 5% of the titanium was able to pass through 0.45 or 0.7 μm pores. Two white paints contained 110 μg Ti/mg while three sealants (i.e., prime coat paint) contained less titanium (25 to 40 μg Ti/mg). This research showed that while many white-colored products contained titanium, it was not a prerequisite. Although several of these product classes contained low amounts of titanium, their widespread use and disposal down the drain and eventually to WWTPs deserves attention. A Monte Carlo human exposure analysis to TiO2 through foods identified children as having the highest exposures because TiO2 content of sweets is higher than other food products, and that a typical exposure for a US adult may be on the order of 1 mg Ti per kilogram body weight per day. Thus, because of the millions of tons of titanium based white pigment used annually, testing should focus on food-grade TiO2 (E171) rather than that adopted in many environmental health and safety tests (i.e., P25), which is used in much lower amounts in products less likely to enter the environment (e.g., catalyst supports, photocatalytic coatings). PMID:22260395

Action-based sensory encoding in spinal sensorimotor circuits.

PubMed

Schouenborg, Jens

2008-01-01

The concept of a modular organisation of the spinal withdrawal reflex circuits has proven to be fundamental for the understanding of how the spinal cord is organised and how the sensorimotor circuits translate sensory information into adequate movement corrections. Recent studies indicate that a task-related body representation is engraved at the network level through learning-dependent mechanisms involving an active probing procedure termed 'somatosensory imprinting' during development. It was found that somatosensory imprinting depends on the tactile input that is associated with spontaneous movements that occur during sleep and results in elimination of erroneous connections and establishment of correct connections. In parallel studies it was found that the strength of the first order tactile synapses in rostrocaudally elongated zones in the adult dorsal horn in the lower lumbar cord is related to the modular organisation of the withdrawal reflexes. Hence, the topographical organisation of the tactile input to this spinal area seems to be action-based rather than a simple body map as previously thought. Far from being innate and adult like at birth, the adult organisation seems to emerge from an initial 'floating' and diffuse body representation with many inappropriate connections through profound activity-dependent rearrangements of afferent synaptic connections. It is suggested that somatosensory imprinting plays a key role in the self-organisation of the spinal cord during development.

Modular robot

DOEpatents

Ferrante, T.A.

1997-11-11

A modular robot may comprise a main body having a structure defined by a plurality of stackable modules. The stackable modules may comprise a manifold, a valve module, and a control module. The manifold may comprise a top surface and a bottom surface having a plurality of fluid passages contained therein, at least one of the plurality of fluid passages terminating in a valve port located on the bottom surface of the manifold. The valve module is removably connected to the manifold and selectively fluidically connects the plurality of fluid passages contained in the manifold to a supply of pressurized fluid and to a vent. The control module is removably connected to the valve module and actuates the valve module to selectively control a flow of pressurized fluid through different ones of the plurality of fluid passages in the manifold. The manifold, valve module, and control module are mounted together in a sandwich-like manner and comprise a main body. A plurality of leg assemblies are removably connected to the main body and are removably fluidically connected to the fluid passages in the manifold so that each of the leg assemblies can be selectively actuated by the flow of pressurized fluid in different ones of the plurality of fluid passages in the manifold. 12 figs.

PET fiber fabrics modified with bioactive titanium oxide for bone substitutes.

PubMed

Kokubo, Tadashi; Ueda, Takahiro; Kawashita, Masakazu; Ikuhara, Yuichi; Takaoka, Gikan H; Nakamura, Takashi

2008-02-01

A rectangular specimen of polyethylene terephthalate (PET) was soaked in a titania solution composed of titanium isopropoxide, water, ethanol and nitric acid at 25 degrees C for 1 h. An amorphous titanium oxide was formed uniformly on the surface of PET specimen, but did not form an apatite on its surface in a simulated body fluid (SBF) within 3 d. The PET plate formed with the amorphous titanium oxide was subsequently soaked in water or HCl solutions with different concentrations at 80 degrees C for different periods of time. The titanium oxide on PET was transformed into nano-sized anatase by the water treatment and into nano-sized brookite by 0.10 M HCl treatment at 80 degrees C for 8 d. The former did not form the apatite on its surface in SBF within 3 d, whereas the latter formed the apatite uniformly on its surface. Adhesive strength of the titanium oxide and apatite layers to PET plate was increased by pre-treatment of PET with 2 wt% NaOH solution at 40 degrees C for 2 h. A two-dimensional fabric of PET fibers 24 microm in diameter was subjected to the NaOH pre-treatment at 40 degrees C, titania solution treatment at 25 degrees C and subsequent 0.10 M HCl treatment at 80 degrees C. Thus treated PET fabric formed the apatite uniformly on surfaces of individual fibers constituting the fabric in SBF within 3 d. Two or three dimensional PET fabrics modified with the nano-sized brookite on surfaces of the individual fibers constituting the fabric by the present method are believed to be useful as flexible bone substitutes, since they could be integrated with living bone through the apatite formed on their constituent fibers.

Mechanical design optimization of bioabsorbable fixation devices for bone fractures.

PubMed

Lovald, Scott T; Khraishi, Tariq; Wagner, Jon; Baack, Bret

2009-03-01

Bioabsorbable bone plates can eliminate the necessity for a permanent implant when used to fixate fractures of the human mandible. They are currently not in widespread use because of the low strength of the materials and the requisite large volume of the resulting bone plate. The aim of the current study was to discover a minimally invasive bioabsorbable bone plate design that can provide the same mechanical stability as a standard titanium bone plate. A finite element model of a mandible with a fracture in the body region is subjected to bite loads that are common to patients postsurgery. The model is used first to determine benchmark stress and strain values for a titanium plate. These values are then set as the limits within which the bioabsorbable bone plate must comply. The model is then modified to consider a bone plate made of the polymer poly-L/DL-lactide 70/30. An optimization routine is run to determine the smallest volume of bioabsorbable bone plate that can perform and a titanium bone plate when fixating fractures of this considered type. Two design parameters are varied for the bone plate design during the optimization analysis. The analysis determined that a strut style poly-L-lactide-co-DL-lactide plate of 690 mm2 can provide as much mechanical stability as a similar titanium design structure of 172 mm2. The model has determined a bioabsorbable bone plate design that is as strong as a titanium plate when fixating fractures of the load-bearing mandible. This is an intriguing outcome, considering that the polymer material has only 6% of the stiffness of titanium.

METHOD OF MAKING METAL BONDED CARBON BODIES

DOEpatents

Goeddel, W.V.; Simnad, M.T.

1961-09-26

A method of producing carbon bodies having high structural strength and low permeability is described. The method comprises mixing less than 10 wt.% of a diffusional bonding material selected from the group consisting of zirconium, niobium, molybdenum, titanium, nickel, chromium, silicon, and decomposable compounds thereof with finely divided particles of carbon or graphite. While being maintained at a mechanical pressure over 3,000 psi, the mixture is then heated uniformly to a temperature of 1500 deg C or higher, usually for less than one hour. The resulting carbon bodies have a low diffusion constant, high dimensional stability, and high mechanical strength.

A Comparison of the Scorpion Load Carriage System (SLCS) to the Modular Lightweight Load Carrying Equipment (MOLLE)

DTIC Science & Technology

2003-07-01

volunteer was asked to report wearing Battle Dress Uniform or Under Armor Undergarment) because the reflective markers used for motion capture needed to be...data collection sessions wearing Under Armor Undergarment, combat boots, integrated body armor and Scorpion helmet. Subjects were given time to

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

PubMed

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

2013-09-01

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

Titanium dioxide nanoparticle ingestion alters nutrient absorption in an in vitro model of the small intestine

USDA-ARS?s Scientific Manuscript database

Ingestion of nanoparticles from products such as agricultural chemicals, processed food, and nutritional supplements is nearly unavoidable. The gastrointestinal tract serves as a critical interface and a barrier between the body and the external environment, and is the site of essential nutrient abs...

Design and verification for front mirror-body structure of on-axis three mirror anastigmatic space camera

NASA Astrophysics Data System (ADS)

Wang, Xiaoyong; Guo, Chongling; Hu, Yongli; He, Hongyan

2017-11-01

The primary and secondary mirrors of onaxis three mirror anastigmatic (TMA) space camera are connected and supported by its front mirror-body structure, which affects both imaging performance and stability of the camera. In this paper, the carbon fiber reinforced plastics (CFRP) thin-walled cylinder and titanium alloy connecting rod have been used for the front mirror-body opto-mechanical structure of the long-focus on-axis and TMA space camera optical system. The front mirror-body component structure has then been optimized by finite element analysis (FEA) computing. Each performance of the front mirror-body structure has been tested by mechanics and vacuum experiments in order to verify the validity of such structure engineering design.

Prototyped grafting plate for reconstruction of mandibular defects.

PubMed

Zhou, Libin; Wang, Peilin; Han, Haolun; Li, Baowei; Wang, Hongnan; Wang, Gang; Zhao, Jinlong; Liu, Yanpu; Wu, Wei

2014-12-01

To esthetically and functionally restore a 40-mm canine mandibular discontinuity defect using a custom-made titanium bone-grafting plate in combination with autologous iliac bone grafts. Individualized titanium bone-grafting plates were manufactured using a series of techniques, including reverse engineering, computer aided design, rapid prototyping and titanium casting. A 40-mm discontinuous defect in the right mandibular body was created in 9 hybrid dogs. The defect was restored immediately using the customized plate in combination with autologous cancellous iliac blocks. Sequential radionuclide bone imaging was performed to evaluate the bone metabolism and reconstitution of the grafts. The specimens were evaluated by biomechanical testing, 3-dimensional microcomputed tomographic scanning, and histological examination. The results revealed that the symmetry of the mandibles was reconstructed using the customized grafting plate, and the bony continuity of the mandibles was restored. By 12 weeks after the operation, the cancellous iliac grafts became a hard bone block, which was of comparable strength to native mandibles. A fibrous tissue intermediate was found between the remodelled bone graft and the titanium plate. The results indicate that the prototyped grafting plate can be used to restore mandibular discontinuous defects, and satisfactory aesthetical and functional reconstruction can be achieved. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Early interactions between leukocytes and three different potentially bioactive titanium surface modifications.

PubMed

Arvidsson, Anna; Malmberg, Per; Kjellin, Per; Currie, Fredrik; Arvidsson, Martin; Franke Stenport, Victoria

2011-05-01

The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p < 0.0005). The SBF immersion resulted in an increased respiratory burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response. Copyright © 2011 Wiley Periodicals, Inc.

SemantEco: a semantically powered modular architecture for integrating distributed environmental and ecological data

USGS Publications Warehouse

Patton, Evan W.; Seyed, Patrice; Wang, Ping; Fu, Linyun; Dein, F. Joshua; Bristol, R. Sky; McGuinness, Deborah L.

2014-01-01

We aim to inform the development of decision support tools for resource managers who need to examine large complex ecosystems and make recommendations in the face of many tradeoffs and conflicting drivers. We take a semantic technology approach, leveraging background ontologies and the growing body of linked open data. In previous work, we designed and implemented a semantically enabled environmental monitoring framework called SemantEco and used it to build a water quality portal named SemantAqua. Our previous system included foundational ontologies to support environmental regulation violations and relevant human health effects. In this work, we discuss SemantEco’s new architecture that supports modular extensions and makes it easier to support additional domains. Our enhanced framework includes foundational ontologies to support modeling of wildlife observation and wildlife health impacts, thereby enabling deeper and broader support for more holistically examining the effects of environmental pollution on ecosystems. We conclude with a discussion of how, through the application of semantic technologies, modular designs will make it easier for resource managers to bring in new sources of data to support more complex use cases.

Apparatus for inspecting piping

DOEpatents

Zollingger, W. Thor; Appel, D. Keith; Park, Larry R.

1995-01-01

An inspection rabbit for inspecting piping systems having severe bends therein. The rabbit consists of a flexible, modular body containing a miniaturized eddy current inspection probe, a self-contained power supply for proper operation of the rabbit, an outer surface that allows ease of movement through piping systems and means for transmitting data generated by the inspection device. The body is preferably made of flexible polyvinyl chloride (PVC) tubing or, alternatively, silicone rubber with a shrink wrapping of polytetrafluoroethylene (TEFLON.RTM.). The body is formed to contain the power supply, preferably a plurality of batteries, and a spool of communication wire that connects to a data processing computer external to the piping system.

Impaction durability of porous polyether-ether-ketone (PEEK) and titanium-coated PEEK interbody fusion devices.

PubMed

Torstrick, F Brennan; Klosterhoff, Brett S; Westerlund, L Erik; Foley, Kevin T; Gochuico, Joanna; Lee, Christopher S D; Gall, Ken; Safranski, David L

2018-05-01

Various surface modifications, often incorporating roughened or porous surfaces, have recently been introduced to enhance osseointegration of interbody fusion devices. However, these topographical features can be vulnerable to damage during clinical impaction. Despite the potential negative impact of surface damage on clinical outcomes, current testing standards do not replicate clinically relevant impaction loading conditions. The purpose of this study was to compare the impaction durability of conventional smooth polyether-ether-ketone (PEEK) cervical interbody fusion devices with two surface-modified PEEK devices that feature either a porous structure or plasma-sprayed titanium coating. A recently developed biomechanical test method was adapted to simulate clinically relevant impaction loading conditions during cervical interbody fusion procedures. Three cervical interbody fusion devices were used in this study: smooth PEEK, plasma-sprayed titanium-coated PEEK, and porous PEEK (n=6). Following Kienle et al., devices were impacted between two polyurethane blocks mimicking vertebral bodies under a constant 200 N preload. The posterior tip of the device was placed at the entrance between the polyurethane blocks, and a guided 1-lb weight was impacted upon the anterior face with a maximum speed of 2.6 m/s to represent the strike force of a surgical mallet. Impacts were repeated until the device was fully impacted. Porous PEEK durability was assessed using micro-computed tomography (µCT) pre- and postimpaction. Titanium-coating coverage pre- and postimpaction was assessed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. Changes to the surface roughness of smooth and titanium-coated devices were also evaluated. Porous PEEK and smooth PEEK devices showed minimal macroscopic signs of surface damage, whereas the titanium-coated devices exhibited substantial visible coating loss. Quantification of the porous PEEK deformation demonstrated that the porous structure maintained a high porosity (>65%) following impaction that would be available for bone ingrowth, and exhibited minimal changes to pore size and depth. SEM and energy dispersive X-ray spectroscopy analysis of titanium-coated devices demonstrated substantial titanium coating loss after impaction that was corroborated with a decrease in surface roughness. Smooth PEEK showed minimal signs of damage using SEM, but demonstrated a decrease in surface roughness. Although recent surface modifications to interbody fusion devices are beneficial for osseointegration, they may be susceptible to damage and wear during impaction. The current study found porous PEEK devices to show minimal damage during simulated cervical impaction, whereas titanium-coated PEEK devices lost substantial titanium coverage. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Characterization of the fretting corrosion behavior, surface and debris from head-taper interface of two different modular hip prostheses.

PubMed

Dos Santos, Claudio T; Barbosa, Cassio; Monteiro, Maurício J; Abud, Ibrahim C; Caminha, Ieda M V; Roesler, Carlos R M

2016-09-01

Modular hip prostheses are flexible to match anatomical variations and to optimize mechanical and tribological properties of each part by using different materials. However, micromotions associated with the modular components can lead to fretting corrosion and, consequently, to release of debris which can cause adverse local tissue reactions in human body. In the present study, the surface damage and residues released during in vitro fretting corrosion tests were characterized by stereomicroscope, SEM and EDS. Two models of modular hip prosthesis were studied: Model SS/Ti Cementless whose stem was made of ASTM F136 Ti-6Al-4V alloy and whose metallic head was made of ASTM F138 austenitic stainless steel, and Model SS/SS Cemented with both components made of ASTM F138 stainless steel. The fretting corrosion tests were evaluated according to the criteria of ASTM F1875 standard. Micromotions during the test caused mechanical wear and material loss in the head-taper interface, resulting in fretting-corrosion. Model SS/SS showed higher grade of corrosion. Different morphologies of debris predominated in each model studied. Small and agglomerated particles were observed in the Model SS/Ti and irregular particles in the Model SS/SS. After 10 million cycles, the Model SS/Ti was more resistant to fretting corrosion than the Model SS/SS. Copyright © 2016 Elsevier Ltd. All rights reserved.

Corrosion and surface modification on biocompatible metals: A review.

PubMed

Asri, R I M; Harun, W S W; Samykano, M; Lah, N A C; Ghani, S A C; Tarlochan, F; Raza, M R

2017-08-01

Corrosion prevention in biomaterials has become crucial particularly to overcome inflammation and allergic reactions caused by the biomaterials' implants towards the human body. When these metal implants contacted with fluidic environments such as bloodstream and tissue of the body, most of them became mutually highly antagonistic and subsequently promotes corrosion. Biocompatible implants are typically made up of metallic, ceramic, composite and polymers. The present paper specifically focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys. This article also takes a close look at the effect of corrosion towards the implant and human body and the mechanism to improve it. Due to this corrosion delinquent, several surface modification techniques have been used to improve the corrosion behavior of biocompatible metals such as deposition of the coating, development of passivation oxide layer and ion beam surface modification. Apart from that, surface texturing methods such as plasma spraying, chemical etching, blasting, electropolishing, and laser treatment which used to improve corrosion behavior are also discussed in detail. Introduction of surface modifications to biocompatible metals is considered as a "best solution" so far to enhanced corrosion resistance performance; besides achieving superior biocompatibility and promoting osseointegration of biocompatible metals and alloys. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon/PEEK composite materials as an alternative for stainless steel/titanium hip prosthesis: a finite element study.

PubMed

Rezaei, Farshid; Hassani, Kamran; Solhjoei, Nosratollah; Karimi, Alireza

2015-12-01

Total hip replacement (THR) has been ranked within the most typical surgical processes in the world. The durability of the prosthesis and loosening of prosthesis are the main concerns that mostly reported after THR surgeries. In THR, the femoral prosthesis can be fixed by either cement or cementless methods in the patient's bones. In both procedures, the stability of the prosthesis in the hosted bone has a key asset in its long-term durability and performance. This study aimed to execute a comparative finite element simulation to assess the load transfer between the prosthesis, which is made of carbon/PEEK composite and stainless steel/titanium, and the femur bone. The mechanical behavior of the cortical bone was assumed as a linear transverse isotropic while the spongy bone was modeled like a linear isotropic material. The implants were made of stainless steel (316L) and titanium alloy as they are common materials for implants. The results showed that the carbon/PEEK composites provide a flatter load transfer from the upper body to the leg compared to the stainless steel/titanium prosthesis. Furthermore, the results showed that the von Mises stress, principal stress, and the strain in the carbon/PEEK composites prosthesis were significantly lower than that made of the stainless steel/titanium. The results also imply that the carbon/PEEK composites can be applied to introduce a new optimum design for femoral prosthesis with adjustable stiffness, which can decrease the stress shielding and interface stress. These findings will help clinicians and biomedical experts to increase their knowledge about the hip replacement.

Surface Modification of Porous Titanium Granules for Improving Bioactivity.

PubMed

Karaji, Zahra Gorgin; Houshmand, Behzad; Faghihi, Shahab

The highly porous titanium granules are currently being used as bone substitute material and for bone tissue augmentation. However, they suffer from weak bone bonding ability. The aim of this study was to create a nanostructured surface oxide layer on irregularly shaped titanium granules to improve their bioactivity. This could be achieved using optimized electrochemical anodic oxidation (anodizing) and heat treatment processes. The anodizing process was done in an ethylene glycol-based electrolyte at an optimized condition of 60 V for 3 hours. The anodized granules were subsequently annealed at 450°C for 1 hour. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) were used to characterize the surface structure and morphology of the granules. The in vitro bioactivity of the samples was evaluated by immersion of specimens in simulated body fluid (SBF) for 1, 2, and 3 weeks. The human osteoblastic sarcoma cell line, MG63, was used to evaluate cell viability on the samples using dimethylthiazol-diphenyl tetrazolium bromide (MTT) assay. The results demonstrated the formation of amorphous nanostructured titanium oxide after anodizing, which transformed to crystalline anatase and rutile phases upon heat treatment. After immersion in SBF, spherical aggregates of amorphous calcium phosphate were formed on the surface of the anodized sample, which turned into crystalline hydroxyapatite on the surface of the anodized annealed sample. No cytotoxicity was detected among the samples. It is suggested that anodic oxidation followed by heat treatment could be used as an effective surface treatment procedure to improve bioactivity of titanium granules implemented for bone tissue repair and augmentation.

Process for fabrication of cermets

DOEpatents

Landingham, Richard L [Livermore, CA

2011-02-01

Cermet comprising ceramic and metal components and a molten metal infiltration method and process for fabrication thereof. The light weight cermets having improved porosity, strength, durability, toughness, elasticity fabricated from presintered ceramic powder infiltrated with a molten metal or metal alloy. Alumina titanium cermets biocompatible with the human body suitable for bone and joint replacements.

A carbon fiber reinforced polymer cage for vertebral body replacement: technical note.

PubMed

Ciappetta, P; Boriani, S; Fava, G P

1997-11-01

We analyzed the surgical technique used for the replacement of damaged vertebral bodies of the thoracolumbar spine and the carbon fiber reinforced polymer (CFRP) cages that are used to replace the pathological vertebral bodies. We also evaluated the biomechanical properties of carbon composite materials used in spinal surgery. The surgical technique of CFRP implants may be divided into two distinct steps, i.e., assembling the components that will replace the pathological vertebral bodies and connecting the cage to an osteosynthetic system to immobilize the cage. The CFRP cages, made of Ultrapek polymer and AS-4 pyrolytic carbon fiber (AcroMed, Rotterdam, The Netherlands), are of different sizes and may be placed one on top of the other and fixed together with a titanium rod. These components are hollow to allow fragments of bone to be pressed manually into them and present threaded holes at 15, 30, and 90 degrees on the external surface, permitting the insertion of screws to connect the cage to an anterior or posterior osteosynthetic system. To date, we have used CFRP cages in 13 patients undergoing corporectomies and 10 patients undergoing spondylectomies. None of our patients have reported complications. CFRP implants offer several advantages compared with titanium or surgical grade stainless steel implants, demonstrating high versatility and outstanding biological and mechanical properties. Furthermore, CFRP implants are radiolucent and do not hinder radiographic evaluation of bone fusion, allowing for better follow-up studies.

OpenWorm: an open-science approach to modeling Caenorhabditis elegans.

PubMed

Szigeti, Balázs; Gleeson, Padraig; Vella, Michael; Khayrulin, Sergey; Palyanov, Andrey; Hokanson, Jim; Currie, Michael; Cantarelli, Matteo; Idili, Giovanni; Larson, Stephen

2014-01-01

OpenWorm is an international collaboration with the aim of understanding how the behavior of Caenorhabditis elegans (C. elegans) emerges from its underlying physiological processes. The project has developed a modular simulation engine to create computational models of the worm. The modularity of the engine makes it possible to easily modify the model, incorporate new experimental data and test hypotheses. The modeling framework incorporates both biophysical neuronal simulations and a novel fluid-dynamics-based soft-tissue simulation for physical environment-body interactions. The project's open-science approach is aimed at overcoming the difficulties of integrative modeling within a traditional academic environment. In this article the rationale is presented for creating the OpenWorm collaboration, the tools and resources developed thus far are outlined and the unique challenges associated with the project are discussed.

Modular liquid-cooled helmet liner for thermal comfort

NASA Technical Reports Server (NTRS)

Williams, B. A.; Shitzer, A.

1974-01-01

A modular liquid-cooled helmet liner made of eight form-fitting neoprene patches was constructed. The liner was integrated into the sweatband of an Army SPH-4 helicopter aircrew helmet. This assembly was tested on four subjects seated in a hot (47 C), humid (40%) environment. Results indicate a marked reduction in the rate of increase of physiological body functions. Rectal temperature, weight loss, heart rate, and strain indices are all reduced to approximately 50% of uncooled levels. The cooling liner removed from 10% to 30% of total metabolic heat produced. This study also demonstrated the technical feasilibity of using a cooling liner in conjunction with a standard hard helmet. Potential applications of the cooling liner in thermally stressful environments are numerous, notably for helicopter and other aircrews.

Surface and corrosion characteristics of carbon plasma implanted and deposited nickel-titanium alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poon, R.W.Y.; Liu, X.Y.; Chung, C.Y.

2005-05-01

Nickel-titanium shape memory alloys (NiTi) are potentially useful in orthopedic implants on account of their super-elastic and shape memory properties. However, the materials are prone to surface corrosion and the most common problem is out-diffusion of harmful Ni ions from the substrate into body tissues and fluids. In order to improve the corrosion resistance and related surface properties, we used the technique of plasma immersion ion implantation and deposition to deposit an amorphous hydrogenated carbon coating onto NiTi and implant carbon into NiTi. Both the deposited amorphous carbon film and carbon plasma implanted samples exhibit much improved corrosion resistances andmore » surface mechanical properties and possible mechanisms are suggested.« less

MICROSCOPE Mission: First Results of a Space Test of the Equivalence Principle.

PubMed

Touboul, Pierre; Métris, Gilles; Rodrigues, Manuel; André, Yves; Baghi, Quentin; Bergé, Joël; Boulanger, Damien; Bremer, Stefanie; Carle, Patrice; Chhun, Ratana; Christophe, Bruno; Cipolla, Valerio; Damour, Thibault; Danto, Pascale; Dittus, Hansjoerg; Fayet, Pierre; Foulon, Bernard; Gageant, Claude; Guidotti, Pierre-Yves; Hagedorn, Daniel; Hardy, Emilie; Huynh, Phuong-Anh; Inchauspe, Henri; Kayser, Patrick; Lala, Stéphanie; Lämmerzahl, Claus; Lebat, Vincent; Leseur, Pierre; Liorzou, Françoise; List, Meike; Löffler, Frank; Panet, Isabelle; Pouilloux, Benjamin; Prieur, Pascal; Rebray, Alexandre; Reynaud, Serge; Rievers, Benny; Robert, Alain; Selig, Hanns; Serron, Laura; Sumner, Timothy; Tanguy, Nicolas; Visser, Pieter

2017-12-08

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[-1±9(stat)±9(syst)]×10^{-15} (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

MICROSCOPE Mission: First Results of a Space Test of the Equivalence Principle

NASA Astrophysics Data System (ADS)

Touboul, Pierre; Métris, Gilles; Rodrigues, Manuel; André, Yves; Baghi, Quentin; Bergé, Joël; Boulanger, Damien; Bremer, Stefanie; Carle, Patrice; Chhun, Ratana; Christophe, Bruno; Cipolla, Valerio; Damour, Thibault; Danto, Pascale; Dittus, Hansjoerg; Fayet, Pierre; Foulon, Bernard; Gageant, Claude; Guidotti, Pierre-Yves; Hagedorn, Daniel; Hardy, Emilie; Huynh, Phuong-Anh; Inchauspe, Henri; Kayser, Patrick; Lala, Stéphanie; Lämmerzahl, Claus; Lebat, Vincent; Leseur, Pierre; Liorzou, Françoise; List, Meike; Löffler, Frank; Panet, Isabelle; Pouilloux, Benjamin; Prieur, Pascal; Rebray, Alexandre; Reynaud, Serge; Rievers, Benny; Robert, Alain; Selig, Hanns; Serron, Laura; Sumner, Timothy; Tanguy, Nicolas; Visser, Pieter

2017-12-01

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10-15 precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ (Ti ,Pt )=[-1 ±9 (stat)±9 (syst)]×10-15 (1 σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

Radical antegrade modular pancreatosplenectomy for adenocarcinomaof the body of the pancreas in a patient with portal annular pancreas, aberrant hepatic artery, and absence of the celiac trunk: A case report.

PubMed

Yuan, Hao; Wu, Pengfei; Chen, Jianmin; Lu, Zipeng; Chen, Lei; Wei, Jishu; Guo, Feng; Cai, Baobao; Yin, Jie; Xu, Dong; Jiang, Kuirong; Miao, Yi

2017-12-01

Portal annular pancreas is a rare anatomic variation, where the uncinated process of the pancreas connects with the dorsal pancreas and the pancreas tissue encases the portal vein (PV), superior mesenteric vein (SMV) or splenic vein (SV). Malignancies are quite uncommon in the patients, who have an annular pancreas especially portal annular pancreas. Ectopic common hepatic artery and absence of the celiac trunk (CT) are the other infrequent abnormalities. A 74-year-old man suffered from upper abdominal and back pain. Contrast enhanced computed tomography indicated a low-density mass in the body of the pancreas. Pathological report showed adenocarcinoma of the body of pancreas after radical antegrade modular pancreatosplenectomy (RAMPS). In the operation, we found the superior vein and portal vein was surrounded by the pancreatic tissue. The left gastric artery and splenic artery originated respectively from abdominal aorta, and celiac trunk was not viewed. In addition, the common hepatic artery was a branch from the superior mesenteric artery. In general, this is a novel clinical case of pancreatic carcinoma happening in the portal annular pancreas which was accompanied with aberrant hepatic artery and absence of the celiac trunk at the same time. Confronted with the pancreatic neoplasms, the possibility of coexistent annular pancreas and arterial variations should be considered.

Apparatus for inspecting piping

DOEpatents

Zollingger, W.T.; Appel, D.K.; Park, L.R.

1995-03-21

An inspection rabbit is described for inspecting piping systems having severe bends therein. The rabbit consists of a flexible, modular body containing a miniaturized eddy current inspection probe, a self-contained power supply for proper operation of the rabbit, an outer surface that allows ease of movement through piping systems and means for transmitting data generated by the inspection device. The body is preferably made of flexible polyvinyl chloride (PVC) tubing or, alternatively, silicone rubber with a shrink wrapping of polytetrafluoroethylene (TEFLON{trademark}). The body is formed to contain the power supply, preferably a plurality of batteries, and a spool of communication wire that connects to a data processing computer external to the piping system. 6 figures.

Topography and nanostructural evaluation of chemically and thermally modified titanium substrates.

PubMed

Salemi, Hoda; Behnamghader, Aliasghar; Afshar, Abdollah

2016-10-01

In this research, the effects of chemical and thermal treatment on the morphological and compositional aspects of titanium substrates and so, potentially, on development of biomimetic bone like layers formation during simulated body fluid (SBF) soaking was investigated. The HF, HF/HNO3 and NaOH solutions were used for chemical treatment and some of alkali-treated samples followed a heat treatment at 600°C. The treated samples before and after soaking were subjected to material characterization tests using scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). White light interferometry (WLI) was used to determine the roughness parameters such as Ra, Rq, RKu and Rsk. The significance of the obtained data was assessed using ANOVA variance analysis between all samples. It was observed that the reaction at grain boundaries and sodium titanate intermediate layers play a great role in the nucleation of calcium phosphate layers. Based on the obtained results in this work, the calcium phosphate microstructure deposited on titanium substrates was more affected by chemical modification than surface topography.

ATOMIC LAYER DEPOSITION OF TITANIUM OXIDE THIN FILMS ONNANOPOROUS ALUMINA TEMPLATES FOR MEDICAL APPLICATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brigmon, R.

2009-05-05

Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of the nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Both the 20 nm and 100 nm titanium oxide-coated nanoporous alumina membranes did not exhibit statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. Inmore » addition, 20 nm pore size titanium oxide-coated nanoporous alumina membranes exposed to ultraviolet light demonstrated activity against Escherichia coli and Staphylococcus aureus bacteria. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for 'smart' drug delivery devices, orthopedic implants, or self-sterilizing medical devices.« less

Fabrication of hydroxyapatite and TiO 2 nanorods on microarc-oxidized titanium surface using hydrothermal treatment

NASA Astrophysics Data System (ADS)

Song, Ho-Jun; Kim, Ji-Woo; Kook, Min-Suk; Moon, Won-Jin; Park, Yeong-Joon

2010-09-01

AC-type microarc oxidation (MAO) and hydrothermal treatment techniques were used to enhance the bioactivity of commercially pure titanium (CP-Ti). The porous TiO 2 layer fabricated by the MAO treatment had a dominant anatase structure and contained Ca and P ions. The MAO-treated specimens were treated hydrothermally to form HAp crystallites on the titanium oxide layer in an alkaline aqueous solution (OH-solution) or phosphorous-containing alkaline solution (POH-solution). A small number of micro-sized hydroxyapatite (HAp) crystallites and a thin layer composed of nano-sized HAps were formed on the Ti-MAO-OH group treated hydrothermally in an OH-solution, whereas a large number of micro-sized HAp crystallites and dense anatase TiO 2 nanorods were formed on the Ti-MAO-POH group treated hydrothermally in a POH-solution. The layer of bone-like apatite that formed on the surface of the POH-treated sample after soaking in a modified simulated body fluid was thicker than that on the OH-treated samples.

Realistic Evaluation of Titanium Dioxide Nanoparticle Exposure in Chewing Gum.

PubMed

Fiordaliso, Fabio; Foray, Claudia; Salio, Monica; Salmona, Mario; Diomede, Luisa

2018-06-20

There is growing concern about the presence of nanoparticles (NPs) in titanium dioxide (TiO 2 ) as food additive (E171). To realistically estimate the number and the amount of TiO 2 NPs ingested with food, we applied a transmission electron microscopy method combined with inductively coupled plasma optical emission spectrometry. Different percentages of TiO 2 NPs (6-18%) were detected in E171 from various suppliers. In the eight chewing gums analyzed as food prototypes, TiO 2 NPs were absent in one sample and ranged 0.01-0.66 mg/gum, corresponding to 7-568 billion NPs/gum, in the other seven. We estimated that the mass-based TiO 2 NPs ingested with chewing gums by the European population ranged from 0.28 to 112.40 μg/kg b.w./day, and children ingested more nanosized titanium than adolescents and adults. Although this level may appear negligible it corresponds to 0.1-84 billion TiO 2 NPs/kg b.w/day, raising important questions regarding their potential accumulation in the body, possibly causing long-term effects on consumers' health.

Mechanical properties of titanium-hydroxyapatite (Ti-HA) composite coating on stainless steel prepared by thermal spraying

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Azhar, N. H.; Talari, M. K.; Yahaya, Sabrina M.; Sulaiman, S.; Ismail, M. I. S.

2017-09-01

Addition of hydroxyapatite (HA) can enhance the bioactivity of the common metallic implant due to its similarity with natural bones and teeth. In this investigation, high velocity oxy-fuel (HVOFT) technique was used to deposit titanium-hydroxyapatite (Ti-HA) composite on stainless steel substrate plate with different percentage of HA for biomedical applications. The aim of this research is to investigate the mechanical properties of Ti-HA coating such as hardness, adhesion strength and wear behaviour. The hardness and strength was determined by using SHIMADZU-microhardness Vickers tester and PosiTest AT portable adhesion tester respectively. The wear test was performed by using pin-on-disk equipment and field emission scanning electron microscope (FESEM) used to determine the extent of surface damage. From the results obtained, mechanical properties such as hardness and adhesion strength of titanium (Ti) coating decreased with the increased of HA contents. Meanwhile, the coefficient of friction of Ti-10% HA coating shows the highest value compare to others as three-body abrasion had occurred during the test.

Structural and surface property characterization of titanium dioxide nanotubes for orthopedic implants

NASA Astrophysics Data System (ADS)

Shokuhfar, Tolou

This research focused on the to modification of the surface structure of titanium implants with nanostructured morphology of TiO2 nanotubes and studied the interaction of nanotubes with osteoblast cells to understand the parameters that affect the cell growth. The electrical, mechanical, and structural properties of TiO2 nanotubes were characterized to establish a better understanding on the properties of such nanoscale morphological structures. To achieve the objectives of this research work I transformed the titanium and its alloys, either in bulk sheet form, bulk machined form, or thin film deposited on another substrate into a surface of titania nanotubes using a low cost and environmentally friendly process. The process requires only a simple electrolyte, low cost electrode, and a DC power supply. With this simple approach of scalable nanofabrication, a typical result is nanotubes that are each approximately 100nm in diameter and have a wall thickness of about 20nm. By changing the fabrication parameters, independent nanotubes can be fabricated with open volume between them. Titanium in this form is termed onedimensional since electron transport is narrowly confined along the length of the nanotube. My Ph.D. accomplishments have successfully shown that osteoblast cells, the cells that are the precursors to bone, have a strong tendency to attach to the inside and outside of the titanium nanotubes onto which they are grown using their filopodia -- cell's foot used for locomotion -- anchored to titanium nanotubes. In fact it was shown that the cell prefers to find many anchoring sites. These sites are critical for cell locomotion during the first several weeks of maturity and upon calcification as a strongly anchored bone cell. In addition I have shown that such a surface has a greater cell density than a smooth titanium surface. My work also developed a process that uses a focused and controllably rastered ion beam as a nano-scalpel to cut away sections of the osteoblast cells to probe the attachment beneath the main cell body. Ultimately the more rapid growth of osteoblasts, coupled with a stronger cell-surface interface, could provide cost reduction, shorter rehabilitation, and fewer follow-on surgeries due to implant loosening.

A model of adsorption of albumin on the implant surface titanium and titanium modified carbon coatings (MWCNT-EPD). 2D correlation analysis

NASA Astrophysics Data System (ADS)

Wesełucha-Birczyńska, Aleksandra; Stodolak-Zych, Ewa; Piś, Wojciech; Długoń, Elżbieta; Benko, Aleksandra; Błażewicz, Marta

2016-11-01

Common materials used as orthopedic implants are titanium and its alloys. To improve its compatibility with the environment of a living organism titanium implant surfaces are covered with bioactive layers of MWCNT. During the insertion into a living organism such material is exposed to direct contact with the patient's blood, which includes proteins - eg. albumin. The adsorption of albumin may constitute one of the early stages of implant surface modification serving cell adhesion. An analysis of this phenomenon in terms of the kinetics of deposition of protein on the surface of the implant confirms its biocompatibility in vivo. The proposed working model of the adsorption of albumin allows for choosing the best of time for the protein to form a stable connection with the surface of the titanium implant. Traditional methods of materials engineering and chemistry allow for the obtaining of information about the presence of a protein on the surface (UV-Vis, the wettability). The application of 2D correlation analysis, in turn, gains insight into the dynamics of the changes associated with the deposition of protein (the formation of a uniform layer, the change in conformation). This analysis has allowed for the selection of an optimal time of protein adsorption to the surface of the implant. Better compatibility with the body of the implant provides its modification by introducing layers that accelerate the material-tissue interactions. Such a composition is a layer of carbon nanotubes (MWCNTs) deposited on titanium by the electrophoretic (EPD) method. Using Raman spectroscopy and analyzing the spectra with the 2D correlation method it is possible to gain insight into the molecular structure of this layer. Our studies indicate that albumin in contact with the surface of titanium has obtained stable conformation after 30 min (confirmed by: UV-Vis, Raman). Shifts of the CH2, CH3 stretching bands position as well as an analysis of the amide I band confirms this conformation. The dynamics of these changes are noticed as correlation peaks observed on 2D maps.

Investigation of boundary conditions for biomimetic HA deposition on titanium oxide surfaces.

PubMed

Lindgren, M; Astrand, M; Wiklund, U; Engqvist, H

2009-07-01

To improve the clinical outcome of metal implants, i.e. earlier loading and reduction of the incidence of revision surgery, better bone bonding ability is wanted. One method to achieve this is to change the surface chemistry to give a surface that facilitates bone bonding in vivo, i.e. a bioactive surface. Crystalline titanium oxide has recently been proven to be bioactive in vitro and is an interesting option to the more common hydroxylapatite (HA) coatings on implants. A materials possible in vitro bioactivity is tested through soaking in simulated body fluid and studies of possible HA formation on the surface. For bioactive materials, the formed HA layer can also be used as a coating. The aim of the current paper is to investigate some boundary conditions for HA formation on crystalline titanium oxide surfaces regarding influence from coating thickness, soaking time and soaking temperature. The influence from soaking time and temperature on the HA growth were investigated on oxidised Ti samples, (24 h at 800 degrees C) resulting in a rutile surface structure. The oxidised samples were tested at three temperatures (4, 37 and 65 degrees C) and four times (1 h, 1 day, 1 week and 4 weeks). The influence from titanium coating thickness on the HA growth was investigated via depositing thin films of crystalline titanium dioxide on Ti plates using a reactive magnetron sputtering process. Four different PVD runs with coating thicknesses between 19 and 74 nm were tested. The soaking temperature had an effect on the HA formation and growth on both rutile surfaces and native oxide on Ti substrates. Higher temperatures lead to easier formation of HA. It was even possible, at 65 degrees C, to grow HA on native titanium oxide from soaking in PBS. The coating quality was better for HA formed at 65 degrees C compared to 37 degrees C. All PVD-coatings showed HA growth after 1 week in PBS at 37 degrees C, thus even very thin coatings of crystalline titanium oxide coatings are bioactive.

Coatings of titanium substrates with xCaO · (1 - x)SiO2 sol-gel materials: characterization, bioactivity and biocompatibility evaluation.

PubMed

Catauro, M; Papale, F; Bollino, F

2016-01-01

The objective of this study has been to develop low temperature sol-gel coatings to modify the surface of commercially pure titanium grade 4 (a material generally used in dental application) and to evaluate their bioactivity and biocompatibility on the substrate. Glasses of composition expressed by the following general formula xCaO · (1 - x)SiO2 (0.0

In vivo performance of two different hydroxyapatite coatings on titanium prepared by discharging in electrolytes.

PubMed

Yamamoto, Hiroki; Shibata, Yo; Tachikawa, Tetsuhiko; Miyazaki, Takashi

2006-07-01

This study reports a discharging method for bone-like carbonated HA (cHA)-coating (Ca/P 1.71) and stoichiometric HA (sHA)-coating (Ca/P 1.67) with micrometer order thicknesses on titanium plates, using modified body fluid and acidic calcium phosphate solutions, respectively. In vivo histological performance of the HA coatings prepared by discharging in electrolytes was evaluated. Bone-contact indexes of HA coatings were measured microscopically. Additionally, bone-coating interface was analyzed by scanning electron microscopy and the use of an electron probe microanalyzer. Results demonstrated that there was no significant difference in contact index between HA coatings. However, the cHA coating was practically replaced by immature bone, and the titanium metal substrate was directly connected to the bone structure whereas the sHA coating layer remained and was partially detached from the titanium metal substrate. Since detached coating particles are pathogens, and can cause peri-implantitis, the cHA coating was more favorable than the sHA coating even if contact index was equivalent to that of the sHA coating. It is thought that coating thickness and chemical composition of coatings are important for biological stability of implants. In conclusion, since bone-like thin cHA coating showed high osteoconductivity and bone replacement, bone-like HA is superior to sHA coating for use in dental implants.

Surface texture and composition of titanium brushed with toothpaste slurries of different pHs.

PubMed

Hossain, Awlad; Okawa, Seigo; Miyakawa, Osamu

2007-02-01

This in vitro study characterized the surface texture and composition of titanium brushed with toothpaste slurries of different pHs, and thereby elucidated mechanochemical interactions between the metal and abrasive material in dentifrice. Two fluoride-free toothpastes, which contained crystalline CaHPO(4).2H(2)O and amorphous SiO(2) particles as abrasive, were mixed with acidic buffers to provide slurries of pH 6.8 and 4.8. Specimens were cast from CP Ti, mirror-polished, and then toothbrushed at 120strokes/min for 350,400 strokes under a load of 2.45N. Specimen surfaces were characterized by means of SPM and EPMA. The obtained data were compared with the already reported results of water-diluted alkaline slurries. SPM data of each paste were analyzed using one-way ANOVA, followed by post hoc Tukey test. Irrespective of toothpaste, neutral slurries, as with alkaline slurries, yielded a chemically altered surface with rough texture, whereas acidic slurries formed a chemically clean surface with relatively smooth texture. Mechanochemical polishing effect might be mainly responsible for the cleanness and smoothness. Acidic slurry-induced smooth surface may minimize plaque formation. However, the augmentation of released titanium ions may be adverse to the human body. For evaluation of toothpaste abrasion effects on titanium, paste slurry pH should be taken into account.

The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty.

PubMed

Krull, Annika; Morlock, Michael M; Bishop, Nicholas E

2017-10-01

Intraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. Metal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. Pull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. Intraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength. Copyright © 2017 Elsevier Inc. All rights reserved.

Reduced bacterial growth and increased osteoblast proliferation on titanium with a nanophase TiO2 surface treatment.

PubMed

Bhardwaj, Garima; Webster, Thomas J

2017-01-01

The attachment and initial growth of bacteria on an implant surface dictates the progression of infection. Treatment often requires aggressive antibiotic use, which does not always work. To overcome the difficulties faced in systemic and local antibiotic delivery, scientists have forayed into using alternative techniques, which includes implant surface modifications that prevent initial bacterial adhesion, foreign body formation, and may offer a controlled inflammatory response. The current study focused on using electrophoretic deposition to treat titanium with a nanophase titanium dioxide surface texture to reduce bacterial adhesion and growth. Two distinct nanotopographies were analyzed, Ti-160, an antimicrobial surface designed to greatly reduce bacterial colonization, and Ti-120, an antimicrobial surface with a topography that upregulates osteoblast activity while reducing bacterial colonization; the number following Ti in the nomenclature represents the atomic force microscopy root-mean-square roughness value in nanometers. There was a 95.6% reduction in Staphylococcus aureus (gram-positive bacteria) for the Ti-160-treated surfaces compared to the untreated titanium alloy controls. There was a 90.2% reduction in Pseudomonas aeruginosa (gram-negative bacteria) on Ti-160-treated surfaces compared to controls. For ampicillin-resistant Escherichia coli , there was an 81.1% reduction on the Ti-160-treated surfaces compared to controls. Similarly for surfaces treated with Ti-120, there was an 86.8% reduction in S. aureus , an 82.1% reduction in P. aeruginosa , and a 48.6% reduction in ampicillin-resistant E. coli . The Ti-120 also displayed a 120.7% increase at day 3 and a 168.7% increase at day 5 of osteoblast proliferation over standard titanium alloy control surfaces. Compared to untreated surfaces, Ti-160-treated titanium surfaces demonstrated a statistically significant 1 log reduction in S. aureus and P. aeruginosa , whereas Ti-120 provided an additional increase in osteoblast proliferation for up to 5 days, criteria, which should be further studied for a wide range of orthopedic applications.

Hyoid expansion with titanium plate and screw: a human cadaveric study using computer-assisted airway measurement.

PubMed

Toh, Song-Tar; Hsu, Pon-Poh; Tan, Kah Leong Alvin; Lu, Kuo-Sun Peter; Han, Hong-Juan

2013-08-01

Hyoid expansion with suspension can potentially increase the upper airway at the hypopharyngeal level, benefitting patients with sleep-related breathing disorder. To document the effect of hyoid expansion using titanium plate and screw on retrolingual hypopharyngeal airway dimension and to compare the airway dimension after isolated hyoid expansion with hyoid expansion + hyomandibular suspension. Anatomical cadaveric dissection study. This study was performed in a laboratory setting using human cadavers. This is an anatomical feasibility study of hyoid expansion using titanium plate and screw on 10 cadaveric human heads and necks. The hyoid bone is trifractured with bony cuts made just medial to the lesser cornu. The freed hyoid body and lateral segments are expanded and stabilized to a titanium adaptation plate. Computer-assisted airway measurement (CAM) was used to measure the airway dimension at the hypopharynx at the level of the tongue base before and after the hyoid expansion. The expanded hyoid bone was then suspended to the mandible, and the airway dimension was measured again with CAM. Airway dimension after isolated hyoid expansion with hyoid expansion with hyomandibular suspension. RESULTS Hyoid expansion with titanium plate and screw resulted in statistical significant increase in the retrolingual hypopharyngeal airway space in all of the 10 human cadavers. The mean (SD) increase in retroglossal area was 33.4 (13.2) mm² (P < .005) (range, 6.0-58.7 mm²). Hyoid expansion with hyomandibular suspension resulted in a greater degree of airway enlargement. The mean (SD) increase in retroglossal area was 99.4 (15.0) mm² (P < .005) (range, 81.9-127.5 mm²). The retrolingual hypopharyngeal airway space increased with hyoid expansion using titanium plate and screw in our human cadaveric study, measured using CAM. The degree of increase is further augmented with hyomandibular suspension.

Effect of imaging powder and CAD/CAM stone types on the marginal gap of zirconia crowns.

PubMed

Alghazzawi, Tariq F; Al-Samadani, Khalid H; Lemons, Jack; Liu, Perng-Ru; Essig, Milton E; Bartolucci, Alfred A; Janowski, Gregg M

2015-02-01

To compare the marginal gap using different types of die stones and titanium dies with and without powders for imaging. A melamine tooth was prepared and scanned using a laboratory 3-shape scanner to mill a polyurethane die, which was duplicated into different stones (Jade, Lean, CEREC) and titanium. Each die was sprayed with imaging powders (NP, IPS, Optispray, Vita) to form 15 groups. Ten of each combination of stone/titanium and imaging powders were used to mill crowns. A light-bodied impression material was injected into the intaglio surface of each crown and placed on the corresponding die. Each crown was removed, and the monophase material was injected to form a monophase die, which was cut into 8 sections. Digital images were captured using a stereomicroscope to measure marginal gap. Scanning electron microscopy was used to determine the particle size and shape of imaging powders and stones. Marginal gaps ranged from mean (standard deviation) 49.32 to 1.20 micrometers (3.97-42.41 μm). There was no statistical difference (P > .05) in the marginal gap by any combination of stone/titanium and imaging powders. All of the imaging powders had a similar size and rounded shape, whereas the surface of the stones showed different structures. When a laboratory 3-shape scanner is used, all imaging powders performed the same for scanning titanium abutments. However, there was no added value related to the use of imaging powder on die stone. It is recommended that the selection of stone for a master cast be based on the hysical properties. When a laboratory 3-shape scanner is used, the imaging powder is not required for scanning die stone. Whenever scanning titanium implant abutments, select the least expensive imaging powder. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.

Hybrid titanium/biodegradable polymer implants with an hierarchical pore structure as a means to control selective cell movement.

PubMed

Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

2011-01-01

In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical requirements with the polymeric structure.

Hybrid Titanium/Biodegradable Polymer Implants with an Hierarchical Pore Structure as a Means to Control Selective Cell Movement

PubMed Central

Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

2011-01-01

In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. Methodology/Principal Findings A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. Conclusions In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical requirements with the polymeric structure. PMID:21637824

Using Voice Coils to Actuate Modular Soft Robots: Wormbot, an Example.

PubMed

Nemitz, Markus P; Mihaylov, Pavel; Barraclough, Thomas W; Ross, Dylan; Stokes, Adam A

2016-12-01

In this study, we present a modular worm-like robot, which utilizes voice coils as a new paradigm in soft robot actuation. Drive electronics are incorporated into the actuators, providing a significant improvement in self-sufficiency when compared with existing soft robot actuation modes such as pneumatics or hydraulics. The body plan of this robot is inspired by the phylum Annelida and consists of three-dimensional printed voice coil actuators, which are connected by flexible silicone membranes. Each electromagnetic actuator engages with its neighbor to compress or extend the membrane of each segment, and the sequence in which they are actuated results in an earthworm-inspired peristaltic motion. We find that a minimum of three segments is required for locomotion, but due to our modular design, robots of any length can be quickly and easily assembled. In addition to actuation, voice coils provide audio input and output capabilities. We demonstrate transmission of data between segments by high-frequency carrier waves and, using a similar mechanism, we note that the passing of power between coupled coils in neighboring modules-or from an external power source-is also possible. Voice coils are a convenient multifunctional alternative to existing soft robot actuators. Their self-contained nature and ability to communicate with each other are ideal for modular robotics, and the additional functionality of sound input/output and power transfer will become increasingly useful as soft robots begin the transition from early proof-of-concept systems toward fully functional and highly integrated robotic systems.

Resorbable versus titanium plates for orthognathic surgery.

PubMed

Agnihotry, Anirudha; Fedorowicz, Zbys; Nasser, Mona; Gill, Karanjot S

2017-10-04

Recognition of some of the limitations of titanium plates and screws used for the fixation of bones has led to the development of plates manufactured from bioresorbable materials. Whilst resorbable plates appear to offer clinical advantages over metal plates in orthognathic surgery, concerns remain about the stability of fixation and the length of time required for their degradation and the possibility of foreign body reactions. This review compares the use of titanium versus bioresorbable plates in orthognathic surgery and is an update of the Cochrane Review first published in 2007. To compare the effects of bioresorbable fixation systems with titanium systems used during orthognathic surgery. Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 20 January 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 11) in the Cochrane Library (searched 20 January 2017); MEDLINE Ovid (1946 to 20 January 2017); and Embase Ovid (1980 to 20 January 2017). We searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (clinicaltrials.gov; searched 20 January 2017), and the World Health Organization International Clinical Trials Registry Platform (searched 20 January 2017) for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Randomised controlled trials comparing bioresorbable versus titanium fixation systems used for orthognathic surgery in adults. Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias of the included studies. We resolved disagreement by discussion. Clinical heterogeneity between the included trials precluded pooling of data, and only a descriptive summary is presented. This review included two trials, involving 103 participants, one comparing titanium with resorbable plates and screws and the other titanium with resorbable screws. Both studies were at high risk of bias and provided very limited data for the primary outcomes of this review. All participants in one trial suffered mild to moderate postoperative discomfort with no statistically significant difference between the two plating groups at different follow-up times. Mean scores of patient satisfaction were 7.43 to 8.63 (range 0 to 10) with no statistically significant difference between the two groups throughout follow-up. Adverse effects reported in one study were two plate exposures in each group occurring between the third and ninth months. Plate exposures occurred mainly in the posterior maxillary region, except for one titanium plate exposure in the mandibular premolar region. Known causes of infection were associated with loosened screws and wound dehiscence with no statistically significant difference in the infection rate between titanium (3/196), and resorbable (3/165) plates. We do not have sufficient evidence to determine if titanium plates or resorbable plates are superior for fixation of bones after orthognathic surgery. This review provides insufficient evidence to show any difference in postoperative pain and discomfort, level of patient satisfaction, plate exposure or infection for plate and screw fixation using either titanium or resorbable materials.

The Musculoskeletal System. Instructional Materials in Anatomy and Physiology for Pennsylvania Health Occupations Programs.

ERIC Educational Resources Information Center

National Evaluation Systems, Inc., Amherst, MA.

This instructional modular unit with instructor's guide provides materials on aspects of one of the major systems of the human body--the musculoskeletal system. Its purpose is to introduce the student to the structures and functions of the human musculoskeletal system--and the interrelationships of the two--and to familiarize the student with some…

The Circulatory System. Instructional Materials in Anatomy and Physiology for Pennsylvania Health Occupations Programs.

ERIC Educational Resources Information Center

National Evaluation Systems, Inc., Amherst, MA.

This instructional modular unit with instructor's guide provides materials on aspects of one of the major systems of the human body--the circulatory system. Its purpose is to introduce the student to the structures and functions of the human circulatory system--and the interrelationships of the two--and to familiarize the student with some of the…

The Respiratory System. Instructional Materials in Anatomy and Physiology for Pennsylvania Health Occupations Programs.

ERIC Educational Resources Information Center

National Evaluation Systems, Inc., Amherst, MA.

This instructional modular unit with instructor's guide provides materials on aspects of one of the major systems of the human body--the respiratory system. Its purpose is to introduce the student to the structures and functions of the human respiratory system--and the interrelationships of the two--and to famlliarize the student with some of the…

Multipurpose high-pressure high-temperature diamond-anvil cell with a novel high-precision guiding system and a dual-mode pressurization device

NASA Astrophysics Data System (ADS)

Pippinger, Thomas; Miletich, Ronald; Burchard, Michael

2011-09-01

A novel diamond-anvil cell (DAC) design has been constructed and tested for in situ applications at high-pressure (HP) operations and has proved to be suitable even for HP sample environments at non-ambient temperature conditions. The innovative high-precision guiding mechanism, comparable to a dog clutch, consists of perpendicular planar sliding-plane elements and is integrated directly into the base body of the cylindrically shaped DAC. The combination of two force-generating devices, i.e., mechanical screws and an inflatable gas membrane, allows the user to choose independently between, and to apply individually, two different forcing mechanisms for pressure generation. Both mechanisms are basically independent of each other, but can also be operated simultaneously. The modularity of the DAC design allows for an easy exchange of functional core-element groups optimized not only for various analytical in situ methods but also for HP operation with or without high-temperature (HT) application. For HP-HT experiments a liquid cooling circuit inside the specific inner modular groups has been implemented to obtain a controlled and limited heat distribution within the outer DAC body.

Titanium is not "the most biocompatible metal" under cathodic potential: The relationship between voltage and MC3T3 preosteoblast behavior on electrically polarized cpTi surfaces.

PubMed

Ehrensberger, Mark T; Sivan, Shiril; Gilbert, Jeremy L

2010-06-15

An electrochemically controlled system has been developed which allows for cell culture directly on electrically polarized metal surfaces with simultaneous control and assessment of the electrochemical current, potential, and impedance of the interface. This system was utilized in this study to assess the interactions between electrochemically polarized commercially pure titanium (cpTi) and MC3T3 preosteoblast cells. Cells were cultured on CpTi for 24 h at static potentials between -1000 mV and +1000 mV vs. Ag/AgCl and cell morphology (SEM and cell area) and viability (MTT and Live-Dead assay) were assessed along with the electrochemical current densities and surface oxide impedance properties. The results indicate that cathodic polarization in the range of -600 mV to -1000 mV markedly reduces the spreading and viability of cells cultured directly on cpTi within 24 h, while anodic polarization (-300 mV to +1000 mV) out to 72 h shows no difference in cell behavior as compared to the OCP condition. Analysis of the relationship between the cell outcomes and the electrochemical current densities and impedance indicated the presence of voltage-dependent electrochemical thresholds (cathodic current density, i(c) > 1.0 microA/cm(2), R(p) < 10(5) Omega cm(2)) which may control the biocompatibility of cpTi. In addition, these outcomes have direct clinical significance for modular orthopedic implants whose potential can shift, via fretting corrosion, down into the range of potentials exhibiting poor cell behavior. (c) 2009 Wiley Periodicals, Inc.

Automated Modular Magnetic Resonance Imaging Clinical Decision Support System (MIROR): An Application in Pediatric Cancer Diagnosis

PubMed Central

Zarinabad, Niloufar; Meeus, Emma M; Manias, Karen; Foster, Katharine

2018-01-01

Background Advances in magnetic resonance imaging and the introduction of clinical decision support systems has underlined the need for an analysis tool to extract and analyze relevant information from magnetic resonance imaging data to aid decision making, prevent errors, and enhance health care. Objective The aim of this study was to design and develop a modular medical image region of interest analysis tool and repository (MIROR) for automatic processing, classification, evaluation, and representation of advanced magnetic resonance imaging data. Methods The clinical decision support system was developed and evaluated for diffusion-weighted imaging of body tumors in children (cohort of 48 children, with 37 malignant and 11 benign tumors). Mevislab software and Python have been used for the development of MIROR. Regions of interests were drawn around benign and malignant body tumors on different diffusion parametric maps, and extracted information was used to discriminate the malignant tumors from benign tumors. Results Using MIROR, the various histogram parameters derived for each tumor case when compared with the information in the repository provided additional information for tumor characterization and facilitated the discrimination between benign and malignant tumors. Clinical decision support system cross-validation showed high sensitivity and specificity in discriminating between these tumor groups using histogram parameters. Conclusions MIROR, as a diagnostic tool and repository, allowed the interpretation and analysis of magnetic resonance imaging images to be more accessible and comprehensive for clinicians. It aims to increase clinicians’ skillset by introducing newer techniques and up-to-date findings to their repertoire and make information from previous cases available to aid decision making. The modular-based format of the tool allows integration of analyses that are not readily available clinically and streamlines the future developments. PMID:29720361

Evaluation of Long Composite Struts

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Wu, K. Chauncey; Phelps, James E.; McKenney, Martin J.; Oremont, Leonard; Barnard, Ansley

2011-01-01

Carbon-epoxy tapered struts are structurally efficient and offer opportunities for weight savings on aircraft and spacecraft structures. Seven composite struts were designed, fabricated and experimentally evaluated through uniaxial loading. The design requirements, analytical predictions and experimental results are presented. Struts with a tapered composite body and corrugated titanium end fittings successfully supported their design ultimate loads with no evidence of failure.

Aggregation and Charge Behavior of Metallic and Nonmetallic Nanoparticles in the Presence of Competing Similarly-Charged Inorganic Ions

EPA Science Inventory

The influence of competing, similarly charged, inorganic ions on the size and charge behavior of suspended titanium-dioxide (nTiO2), silver (nAg) and fullerene (nC60) nanoparticles (NPs) was investigated. Under pH and ionic conditions similar to natural water bodies, Ca2+ induced...

Adverse Reactions to Metal on Metal Are Not Exclusive to Large Heads in Total Hip Arthroplasty.

PubMed

Lombardi, Adolph V; Berend, Keith R; Adams, Joanne B; Satterwhite, Keri L

2016-02-01

There is some suggestion that smaller diameter heads in metal-on-metal total hip arthroplasty (MoM THA) may be less prone to the adverse reactions to metal debris (ARMD) seen with large-diameter heads. We reviewed our population of patients with small head (≤ 32 mm) MoM THA to determine (1) the frequency of ARMD; (2) potential risk factors for ARMD in this population; and (3) the etiology of revision and Kaplan-Meier survivorship with revision for all causes. Small-diameter head MoM devices were used in 9% (347 of 3753) of primary THAs during the study period (January 1996 to March 2005). We generally used these implants in younger, more active, higher-demand patients. Three hundred hips (258 patients) had MoM THA using a titanium modular acetabular component with a cobalt-chromium tapered insert and were available for review with minimum 2-year followup (mean, 10 years; range, 2-19 years). Complete followup was available in 86% of hips (300 of 347). Clinical records and radiographs were reviewed to determine the frequency and etiology of revision. Kaplan-Meier survivorship analysis was performed. ARMD frequency was 5% (14 of 300 hips) and represented 70% (14 of 20) of revisions performed. Using multivariate analysis, no variable tested, including height, weight, body mass index, age, cup diameter, cup angle, use of screws, stem diameter, stem type, head diameter, preoperative clinical score, diagnosis, activity level, or sex, was significant as a risk factor for revision. Twenty hips have been revised: two for infection, four for aseptic loosening, and 14 for ARMD. Kaplan-Meier analysis revealed survival free of component revision for all causes was 95% at 10 years (95% confidence interval [CI], 91%-97%), 92% at 15 years (95% CI, 87%-95%), and 72% at 19 years (95% CI, 43%-90%), and survival free of component revision for aseptic causes was 96% at 10 years (95% CI, 92%-98%), 92% at 15 years (95% CI, 88%-95%), and 73% at 19 years (95% CI, 43%-90%). The late onset and devastating nature of metal-related failures is concerning with this small-diameter MoM device. Although the liner is modular, it cannot be exchanged and full acetabular revision is required. Patients with all MoM THA devices should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Symptomatic patients should undergo thorough investigation and vigilant observation for ARMD. Level IV, therapeutic study.

In vitro assessment of the biological response of Ti6Al4V implants coated with hydroxyapatite microdomains.

PubMed

Clavell, R Salvador; de Llano, J J Martín; Carda, C; Ribelles, J L Gómez; Vallés-Lluch, A

2016-11-01

Dental implantology is still an expanding field of scientific study because of the number of people that receive dental therapies throughout their lives worldwide. Recovery times associated to dental surgery are still long and demand strategies to improve integration of metallic devices with hard tissues. In this work, an in vitro ceramic coating is proposed to improve and accelerate osseointegration of titanium surfaces conceived to be used as dental implants or hip or knee prosthesis, shaped either as dishes or screws. Such coating consists of hydroxyapatite microdomains on the implant surfaces obtained in vitro by immersion of titanium alloy samples (Ti6Al4V) in a simulated body fluid. This titanium alloy is highly used in implant dentistry and trauma surgery, among other fields. Once the immersion times under physiological conditions yielding to different ceramic topographies on this alloy were set, the acellular coating time of major interest so as to optimize its biological development was determined. For this purpose, dental pulp mesenchymal cells were cultured on titanium coated surfaces with different hydroxyapatite outline, and cell adhesion, proliferation and morphology were followed through histological techniques and scanning electron microscopy. It was found that 4 days of acellular hydroxyapatite coating led to a significant cell adhesion on the titanium alloys at an early stage (6 h). Cells tended although to detach from the surface of the coating over time, but those adhered on domains of intricated topography or hydroxyapatite cauliflowers proliferated on them, leading to isolated large cell clusters. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2723-2729, 2016. © 2016 Wiley Periodicals, Inc.

Thermal effects of λ = 808 nm GaAlAs diode laser irradiation on different titanium surfaces.

PubMed

Giannelli, Marco; Lasagni, Massimo; Bani, Daniele

2015-12-01

Diode lasers are widely used in dental laser treatment, but little is known about their thermal effects on different titanium implant surfaces. This is a key issue because already a 10 °C increase over the normal body temperature can induce bone injury and compromise osseo-integration. The present study aimed at evaluating the temperature changes and surface alterations experienced by different titanium surfaces upon irradiation with a λ = 808 nm diode laser with different settings and modalities. Titanium discs with surfaces mimicking different dental implant surfaces including TiUnite and anodized, machined surfaces were laser-irradiated in contact and non-contact mode, and with and without airflow cooling. Settings were 0.5-2.0 W for the continuous wave mode and 10-45 μJ, 20 kHz, 5-20 μs for the pulsed wave mode. The results show that the surface characteristics have a marked influence on temperature changes in response to irradiation. The TiUnite surface, corresponding to the osseous interface of dental implants, was the most susceptible to thermal rise, while the machined surfaces, corresponding to the implant collar, were less affected. In non-contact mode and upon continuous wave emission, the temperature rose above the 50 °C tissue damage threshold. Scanning electron microscopy investigation of surface alterations revealed that laser treatment in contact mode resulted in surface scratches even when no irradiation was performed. These findings indicate that the effects of diode laser irradiation on implant surfaces depend on physical features of the titanium coating and that in order to avoid thermal or physical damage to implant surface the irradiation treatment has to be carefully selected.

Surface characterization and corrosion behavior of calcium phosphate-base composite layer on titanium and its alloys via plasma electrolytic oxidation: A review paper.

PubMed

Rafieerad, A R; Ashra, M R; Mahmoodian, R; Bushroa, A R

2015-12-01

In recent years, calcium phosphate-base composites, such as hydroxyapatite (HA) and carbonate apatite (CA) have been considered desirable and biocompatible coating layers in clinical and biomedical applications such as implants because of the high resistance of the composites. This review focuses on the effects of voltage, time and electrolytes on a calcium phosphate-base composite layer in case of pure titanium and other biomedical grade titanium alloys via the plasma electrolytic oxidation (PEO) method. Remarkably, these parameters changed the structure, morphology, pH, thickness and crystallinity of the obtained coating for various engineering and biomedical applications. Hence, the structured layer caused improvement of the biocompatibility, corrosion resistance and assignment of extra benefits for Osseo integration. The fabricated layer with a thickness range of 10 to 20 μm was evaluated for physical, chemical, mechanical and tribological characteristics via XRD, FESEM, EDS, EIS and corrosion analysis respectively, to determine the effects of the applied parameters and various electrolytes on morphology and phase transition. Moreover, it was observed that during PEO, the concentration of calcium, phosphor and titanium shifts upward, which leads to an enhanced bioactivity by altering the thickness. The results confirm that the crystallinity, thickness and contents of composite layer can be changed by applying thermal treatments. The corrosion behavior was investigated via the potentiodynamic polarization test in a body-simulated environment. Here, the optimum corrosion resistance was obtained for the coating process condition at 500 V for 15 min in Ringer solution. This review has been summarized, aiming at the further development of PEO by producing more adequate titanium-base implants along with desired mechanical and biomedical features. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterisation of DLC films deposited using titanium isopropoxide (TIPOT) at different flow rates.

PubMed

Said, R; Ali, N; Ghumman, C A A; Teodoro, O M N D; Ahmed, W

2009-07-01

In recent years, there has been growing interest in the search for advanced biomaterials for biomedical applications, such as human implants and surgical cutting tools. It is known that both carbon and titanium exhibit good biocompatibility and have been used as implants in the human body. It is highly desirable to deposit biocompatible thin films onto a range of components in order to impart biocompatibility and to minimise wear in implants. Diamond like carbon (DLC) is a good candidate material for achieving biocompatibility and low wear rates. In this study, thin films of diamond-like-carbon DLC were deposited onto stainless steel (316) substrates using C2H2, argon and titanium isopropoxide (TIPOT) precursors. Argon was used to generate the plasma in the plasma enhanced vapour deposition (PECVD) system. A critical coating feature governing the performance of the component during service is film thickness. The as-grown films were in the thickness range 90-100 nm and were found to be dependent on TIPOT flow rate. Atomic force microscopy (AFM) was used to characterise the surface roughness of the samples. As the flow rate of TIPOT increased the average roughness was found to increase in conjunction with the film thickness. Raman spectroscopy was used to investigate the chemical structure of amorphous carbon matrix. Surface tension values were calculated using contact angle measurements. In general, the trend of the surface tension results exhibited an opposite trend to that of the contact angle. The elemental composition of the samples was characterised using a VG ToF SIMS (IX23LS) instrument and X-ray photoelectron spectroscopy (XPS). Surprisingly, SIMS and XPS results showed that the DLC samples did not show evidence of titanium since no peaks representing to titanium appeared on the SIMS/XPS spectra.

[Influence of coping material selection and porcelain firing on marginal and internal fit of computer-aided design/computer- aided manufacturing of zirconia and titanium ceramic implant-supported crowns].

PubMed

Cuiling, Liu; Liyuan, Yang; Xu, Gao; Hong, Shang

2016-06-01

This study aimed to investigate the influence of coping material and porcelain firing on the marginal and internal fit of computer-aided design/computer-aided manufacturing (CAD/CAM) of zirconia ceramic implant- and titanium ceramic implant-supported crowns. Zirconia ceramic implant (group A, n = 8) and titanium metal ceramic implant-supported crowns (group B, n = 8) were produced from copings using the CAD/CAM system. The marginal and internal gaps of the copings and crowns were measured by using a light-body silicone replica technique combined with micro-computed tomography scanning to obtain a three-dimensional image. Marginal gap (MG), horizontal marginal discrepancy (HMD), and axial wall (AW) were measured. Statistical analyses were performed using SPSS 17.0. Prior to porcelain firing, the measurements for MG, HMD, and AW of copings in group A were significantly larger than those in group B (P < 0.05). After porcelain firing, the measurements for MG of crowns in group A were smaller than those in group B (P < 0.05), whereas HMD and AW showed no significant difference between the two groups (P > 0.05). Porcelain firing significantly reduced MG (P < 0.05) in group A but significantly increased MG, HMD, and AW in group B (P < 0.05) HMD and AW were not influenced by porcelain firing in group A (P > 0.05). The marginal fits of CAD/CAM zirconia ceramic implant-supported crowns were superior to those of CAD/CAM titanium ceramic-supported crowns. The fits of both the CAD/CAM zirconia ceramic implant- and titanium ceramic implant-supported crowns were obviously influenced by porcelain firing.

In vitro study of electrodeposited fluoridated hydroxyapatite coating on G-II titanium with a nanostructured TiO2 interlayer.

PubMed

Lin, Jin-Shyong; Tsai, Tzung-Bau; Say, Wen-Ching; Chiu, Chun; Chen, Shih-Hsun

2017-04-04

Titanium and its alloys have been widely used as orthopedic and dental implants for several decades due to their superior mechanical properties, corrosion resistance and biocompatibility. Recently, many researches revealed that the hydroxyapatite coatings on biomedical materials can further improve their biocompatibility and bioactivity. However, hydroxyapatite coatings are easily decomposed, weakening the bonding between implants and bone tissues and resulting in a high dissolution rate in the biological environment. Prolonging the lifetime of hydroxyapatite in implants is valuable for improving postoperative quality. Hydroxyapatite is the primary inorganic component of bones and teeth. A suitable amount of fluoride ions would be beneficial for the formation of fluoridated hydroxyapatite, which can enhance bone-cell response and the acid resistance of enamel. In this study, G-II titanium substrate was anodized to form a TiO 2 interlayer with a nanotube structure. An electrolyte composed of fluoride, calcium and phosphorus ions was prepared for electroplating fluoridated hydroxyapatite (FHA) coatings onto anodized G-II titanium substrates at a constant voltage. The obtained coatings were examined for their microstructure, mechanical properties; moreover, the changes of apatite structure, surface morphology and corrosion resistance were further investigated after immersion in simulated body fluid (SBF) for a number of weeks. The results show that FHA coatings have a higher surface roughness and hardness than plain hydroxyapatite. After immersion in SBF, the FHA coatings induced the nucleation and growth of apatite on the surface and increased their crystallinity. In a potentiodynamic polarization test, FHA coatings exhibited a better anti-corrosion ability than bare G-II titanium substrate in SBF. Additionally, the anodized TiO 2 nanotube improved the adhesion and corrosion resistance of FHA as well.

Surface bioactivity modification of titanium by CO 2 plasma treatment and induction of hydroxyapatite: In vitro and in vivo studies

NASA Astrophysics Data System (ADS)

Hu, Xixue; Shen, Hong; Shuai, Kegang; Zhang, Enwei; Bai, Yanjie; Cheng, Yan; Xiong, Xiaoling; Wang, Shenguo; Fang, Jing; Wei, Shicheng

2011-01-01

Since metallic biomaterials used for orthopedic and dental implants possess a paucity of reactive functional groups, bioactivity modification of these materials is challenging. In the present work, the titanium discs and rods were treated with carbon dioxide plasma and then incubated in a modified simulated body fluid 1.5SBF to obtain a hydroxyapatite layer. Surface hydrophilicity of samples, changes of surface chemistry, surface morphologies of samples, and structural analysis of formed hydroxyapatite were investigated by contact angle to water, X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The results demonstrated that hydrophilicity of titanium surface was improved and hydroxyl groups increased after modification with carbon dioxide plasma treatment. The hydroxyl groups on the surface of titanium were the richest after carbon dioxide plasma treatment under the condition of 20 W for less than 30 s. The hydroxyapatite formability of titanium surface was enhanced by carbon dioxide plasma pretreatment, which was attributed to the surface chemistry. MC3T3-E1 cell as a model cell was cultured on the Ti, CPT-Ti and CPT/SBF-Ti discs in vitro, and the results of the morphology and differentiation of the cell showed that CPT/SBF-Ti was the highest bioactive. The relative parameters of the new bone around the Ti and CPT/SBF-Ti rods including bone mineral density (BMD), a ratio of bone volume to total volume (BV/TV), trabecular thickness (Tb.Th.) and trabecular number (Tb.N.) were analyzed by a micro-computed tomography (micro-CT) after 4-, 8- and 12-week implantation periods in vivo. The results indicated that the CPT/SBF-Ti was more advantageous for new bone formation.

In vitro chemotaxis and tissue remodeling assays quantitatively characterize foreign body reaction.

PubMed

Jannasch, Maren; Weigel, Tobias; Engelhardt, Lisa; Wiezoreck, Judith; Gaetzner, Sabine; Walles, Heike; Schmitz, Tobias; Hansmann, Jan

2017-01-01

Surgical implantation of a biomaterial triggers foreign-body-induced fibrous encapsulation. Two major mechanisms of this complex physiological process are (I) chemotaxis of fibroblasts from surrounding tissue to the implant region, followed by (II) tissue remodeling. As an alternative to animal studies, we here propose a process-aligned in vitro test platform to investigate the material dependency of fibroblast chemotaxis and tissue remodeling mediated by material-resident macrophages. Embedded in a biomimetic three-dimensional collagen hydrogel, chemotaxis of fibroblasts in the direction of macrophage-material-conditioned cell culture supernatant was analyzed by live cell imaging. A combination of statistical analysis with a complementary parameterized random walk model allowed quantitative and qualitative characterization of the cellular walk process. We thereby identified an increasing macrophage-mediated chemotactic potential ranking of biomaterials from glass over polytetrafluorethylene to titanium. To address long-term effects of bio-material-resident macrophages on fibroblasts in a three-dimensional microenvironment, we further studied tissue remodeling by applying macrophage-material-conditioned medium on fibrous in vitro tissue models. A high correlation of the in vitro tissue model to state of the art in vivo study data was found. Titanium exhibited a significantly lower tissue remodeling capacity compared to polytetrafluorethylene. With this approach, we identified a material dependency of both chemotaxis and tissue remodeling processes, strengthening knowledge on their specific contribution to the foreign body reaction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheaffer, P.; Lemar, P.; Honton, E. J.

The Universal Interconnection Technology (UIT) Workshop - sponsored by the U.S. Department of Energy, Distributed Energy and Electric Reliability (DEER) Program, and Distribution and Interconnection R&D - was held July 25-26, 2002, in Chicago, Ill., to: (1) Examine the need for a modular universal interconnection technology; (2) Identify UIT functional and technical requirements; (3) Assess the feasibility of and potential roadblocks to UIT; (4) Create an action plan for UIT development. These proceedings begin with an overview of the workshop. The body of the proceedings provides a series of industry representative-prepared papers on UIT functions and features, present interconnection technology,more » approaches to modularization and expandability, and technical issues in UIT development as well as detailed summaries of group discussions. Presentations, a list of participants, a copy of the agenda, and contact information are provided in the appendices of this document.« less

Carbonaceous cathode with enhanced wettability for aluminum production

DOEpatents

Keller, Rudolf; Gatty, David G.; Barca, Brian J.

2003-09-09

A method of preparing carbonaceous blocks or bodies for use in a cathode in an electrolytic cell for producing aluminum wherein the cell contains an electrolyte and has molten aluminum contacting the cathode, the cathode having improved wettability with molten aluminum. The method comprises the steps of providing a carbonaceous block and a boron oxide containing melt. The carbonaceous block is immersed in the melt and pressure is applied to the melt to impregnate the melt into pores in the block. Thereafter, the carbonaceous block is withdrawn from the melt, the block having boron oxide containing melt intruded into pores therein, the boron oxide capable of reacting with a source of titanium or zirconium or like metal to form titanium or zirconium diboride during heatup or operation of said cell.

Nuclear fuel alloys or mixtures and method of making thereof

DOEpatents

Mariani, Robert Dominick; Porter, Douglas Lloyd

2016-04-05

Nuclear fuel alloys or mixtures and methods of making nuclear fuel mixtures are provided. Pseudo-binary actinide-M fuel mixtures form alloys and exhibit: body-centered cubic solid phases at low temperatures; high solidus temperatures; and/or minimal or no reaction or inter-diffusion with steel and other cladding materials. Methods described herein through metallurgical and thermodynamics advancements guide the selection of amounts of fuel mixture components by use of phase diagrams. Weight percentages for components of a metallic additive to an actinide fuel are selected in a solid phase region of an isothermal phase diagram taken at a temperature below an upper temperature limit for the resulting fuel mixture in reactor use. Fuel mixtures include uranium-molybdenum-tungsten, uranium-molybdenum-tantalum, molybdenum-titanium-zirconium, and uranium-molybdenum-titanium systems.

The Digestive System [and] Instructor's Guide. Instructional Materials in Anatomy and Physiology for Pennsylvania Health Occupations Programs.

ERIC Educational Resources Information Center

National Evaluation Systems, Inc., Amherst, MA.

This instructional modular unit wlth instructor's guide provides materials on important aspects of one of the major systems of the human body--the digestive system. Its purpose is to introduce the student to the structures and functions of the human digestive system--and the interrelationships of the two--and to familiarize the student with some…

Radical antegrade modular pancreatosplenectomy for adenocarcinomaof the body of the pancreas in a patient with portal annular pancreas, aberrant hepatic artery, and absence of the celiac trunk

PubMed Central

Yuan, Hao; Wu, Pengfei; Chen, Jianmin; Lu, Zipeng; Chen, Lei; Wei, Jishu; Guo, Feng; Cai, Baobao; Yin, Jie; Xu, Dong; Jiang, Kuirong; Miao, Yi

2017-01-01

Abstract Rationale: Portal annular pancreas is a rare anatomic variation, where the uncinated process of the pancreas connects with the dorsal pancreas and the pancreas tissue encases the portal vein (PV), superior mesenteric vein (SMV) or splenic vein (SV). Malignancies are quite uncommon in the patients, who have an annular pancreas especially portal annular pancreas. Ectopic common hepatic artery and absence of the celiac trunk (CT) are the other infrequent abnormalities. Patient concerns: A 74-year-old man suffered from upper abdominal and back pain. Diagnoses and Interventions: Contrast enhanced computed tomography indicated a low-density mass in the body of the pancreas. Pathological report showed adenocarcinoma of the body of pancreas after radical antegrade modular pancreatosplenectomy (RAMPS). Outcomes: In the operation, we found the superior vein and portal vein was surrounded by the pancreatic tissue. The left gastric artery and splenic artery originated respectively from abdominal aorta, and celiac trunk was not viewed. In addition, the common hepatic artery was a branch from the superior mesenteric artery. Lessons: In general, this is a novel clinical case of pancreatic carcinoma happening in the portal annular pancreas which was accompanied with aberrant hepatic artery and absence of the celiac trunk at the same time. Confronted with the pancreatic neoplasms, the possibility of coexistent annular pancreas and arterial variations should be considered. PMID:29310347

Process for fabrication of large titanium diboride ceramic bodies

DOEpatents

Moorhead, Arthur J.; Bomar, E. S.; Becher, Paul F.

1989-01-01

A process for manufacturing large, fully dense, high purity TiB.sub.2 articles by pressing powders with a sintering aid at relatively low temperatures to reduce grain growth. The process requires stringent temperature and pressure applications in the hot-pressing step to ensure maximum removal of sintering aid and to avoid damage to the fabricated article or the die.

In vitro bioactivity of a biocomposite fabricated from HA and Ti powders by powder metallurgy method.

PubMed

Ning, C Q; Zhou, Y

2002-07-01

Traditionally, hydroxyapatite was used as a coating material on titanium substrate by various techniques. In the present work, a biocomposite was successfully fabricated from hydroxyapatite and titanium powders by powder metallurgy method. Bioactivity of the composite in a simulated body fluid (SBF) was investigated. Main crystal phases of the as-fabricated composite are found to be Ti2O, CaTiO3, CaO, alpha-Ti and a TiP-like phase. When the composite is immersed in the simulated body fluid for a certain time, a poor-crystallized, calcium-deficient, carbonate-containing apatite film will form on the surface of the composite. The time required to induce apatite nucleation is within 2 h. In addition, the apatite is also incorporated with a little magnesium and chlorine element. It is found that Ti2O has the ability to induce the formation of bone-like apatite in the SBF. And a dissolve of the CaO phase could also provide favorable conditions for the apatite formation, by forming open pores on the surface of the composite and increasing the degree of supersaturation of the SBF with respect to the apatite.

Anodized titanium and stainless steel in contact with CFRP: an electrochemical approach considering galvanic corrosion.

PubMed

Mueller, Yves; Tognini, Roger; Mayer, Joerg; Virtanen, Sannakaisa

2007-09-15

The combination of different materials in an implant gives the opportunity to better fulfill the requirements that are needed to improve the healing process. However, using different materials increases the risk of galvanic coupling corrosion. In this study, coupling effects of gold-anodized titanium, stainless steel for biomedical applications, carbon fiber reinforced polyetheretherketone (CFRP), and CFRP containing tantalum fibers are investigated electrochemically and by long-term immersion experiments in simulated body fluid (SBF). Potentiodynamic polarization experiments (i/E curves) and electrochemical impedance spectroscopy (EIS) of the separated materials showed a passive behavior of the metallic samples. Anodized titanium showed no corrosion attacks, whereas stainless steel is highly susceptibility for localized corrosion. On the other side, an active dissolution behavior of both of the CFRPs in the given environment could be determined, leading to delaminating of the carbon fibers from the matrix. Long-term immersion experiments were carried out using a set-up especially developed to simulate coupling conditions of a point contact fixator system (PC-Fix) in a biological environment. Electrochemical data were acquired in situ during the whole immersion time. The results of the immersion experiments correlate with the findings of the electrochemical investigation. Localized corrosion attacks were found on stainless steel, whereas anodized titanium showed no corrosion attacks. No significant differences between the two CFRP types could be found. Galvanic coupling corrosion in combination with crevice conditions and possible corrosion mechanisms are discussed. Copyright 2007 Wiley Periodicals, Inc.

A new titanium based alloy Ti-27Nb-13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial.

PubMed

Mendes, Marcio W D; Ágreda, Carola G; Bressiani, Ana H A; Bressiani, José C

2016-06-01

Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti-27Nb-13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for >3 days in the SBF solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Contact damage failure analyses of fretting wear behavior of the metal stem titanium alloy-bone cement interface.

PubMed

Zhang, Lanfeng; Ge, Shirong; Liu, Hongtao; Wang, Qingliang; Wang, Liping; Xian, Cory J

2015-11-01

Although cemented titanium alloy is not favored currently in the Western world for its poor clinical and radiography outcomes, its lower modulus of elasticity and good biocompatibility are instrumental for its ability supporting and transforming physical load, and it is more suitable for usage in Chinese and Japanese populations due to their lower body weights and unique femoral characteristics. Through various friction tests of different cycles, loads and conditions and by examining fretting hysteresis loops, fatigue process curves and wear surfaces, the current study investigated fretting wear characteristics and wear mechanism of titanium alloy stem-bone cement interface. It was found that the combination of loads and displacement affected the wear quantity. Friction coefficient, which was in an inverse relationship to load under the same amplitude, was proportional to amplitudes under the same load. Additionally, calf serum was found to both lubricate and erode the wear interface. Moreover, cement fatigue contact areas appeared black/oxidative in dry and gruel in 25% calf serum. Fatigue scratches were detected within contact areas, and wear scars were found on cement and titanium surfaces, which were concave-shaped and ring concave/ convex-shaped, respectively. The coupling of thermoplastic effect and minimal torque damage has been proposed to be the major reason of contact damage. These data will be important for further studies analyzing metal-cement interface failure performance and solving interface friction and wear debris production issues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using Voice Coils to Actuate Modular Soft Robots: Wormbot, an Example

PubMed Central

Nemitz, Markus P.; Mihaylov, Pavel; Barraclough, Thomas W.; Ross, Dylan

2016-01-01

Abstract In this study, we present a modular worm-like robot, which utilizes voice coils as a new paradigm in soft robot actuation. Drive electronics are incorporated into the actuators, providing a significant improvement in self-sufficiency when compared with existing soft robot actuation modes such as pneumatics or hydraulics. The body plan of this robot is inspired by the phylum Annelida and consists of three-dimensional printed voice coil actuators, which are connected by flexible silicone membranes. Each electromagnetic actuator engages with its neighbor to compress or extend the membrane of each segment, and the sequence in which they are actuated results in an earthworm-inspired peristaltic motion. We find that a minimum of three segments is required for locomotion, but due to our modular design, robots of any length can be quickly and easily assembled. In addition to actuation, voice coils provide audio input and output capabilities. We demonstrate transmission of data between segments by high-frequency carrier waves and, using a similar mechanism, we note that the passing of power between coupled coils in neighboring modules—or from an external power source—is also possible. Voice coils are a convenient multifunctional alternative to existing soft robot actuators. Their self-contained nature and ability to communicate with each other are ideal for modular robotics, and the additional functionality of sound input/output and power transfer will become increasingly useful as soft robots begin the transition from early proof-of-concept systems toward fully functional and highly integrated robotic systems. PMID:28078195

Initial investigation of the corrosion stability of craniofacial implants.

PubMed

Beline, Thamara; Vechiato Filho, Aljomar José; Wee, Alvin G; Sukotjo, Cortino; Dos Santos, Daniela Micheline; Brandão, Thaís Bianca; Barão, Valentim Adelino Ricardo

2018-01-01

Although craniofacial implants have been used for retention of facial prostheses, failures are common. Titanium undergoes corrosion in the oral cavity, but the corrosion of craniofacial implants requires evaluation. The purpose of this in vitro study was to investigate the corrosion stability of commercially pure titanium (CP Ti) exposed to simulated human perspiration at 2 different pH levels (5.5 and 8). Fifteen titanium disks were divided into 3 groups (n=5 per group). The control group was subjected to simulated body fluid (SBF) (control). Disks from the 2 experimental groups were immersed in simulated alkaline perspiration (SA K P) and simulated acidic perspiration (SA C P). Electrochemical tests, including open circuit potential (3600 seconds), electrochemical impedance spectroscopy, and potentiodynamic tests were performed according to the standardized method of 3-cell electrodes. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α=.05). Simulated human perspiration reduced the corrosion stability of CP Ti (P<.05). The SBF group presented the lowest capacitance values (P<.05). SA K P and SA C P groups showed increased values of capacitance and showed no statistically significant differences (P>.05) from each other. The increase in capacitance suggests that the acceleration of the ionic exchanges between the CP Ti and the electrolyte leads to a lower corrosion resistance. SA K P reduced the oxide layer resistance of CP Ti (P<.05), and an increased corrosion rate was noted in both simulated human perspiration groups. Craniofacial implants can corrode when in contact with simulated human perspiration, whereas alkaline perspiration shows a more deleterious effect. Perspiration induces a more corrosive effect than simulated body fluid. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda.

PubMed

Smith, Frank W; Goldstein, Bob

2017-05-01

The origin and diversification of segmented metazoan body plans has fascinated biologists for over a century. The superphylum Panarthropoda includes three phyla of segmented animals-Euarthropoda, Onychophora, and Tardigrada. This superphylum includes representatives with relatively simple and representatives with relatively complex segmented body plans. At one extreme of this continuum, euarthropods exhibit an incredible diversity of serially homologous segments. Furthermore, distinct tagmosis patterns are exhibited by different classes of euarthropods. At the other extreme, all tardigrades share a simple segmented body plan that consists of a head and four leg-bearing segments. The modular body plans of panarthropods make them a tractable model for understanding diversification of animal body plans more generally. Here we review results of recent morphological and developmental studies of tardigrade segmentation. These results complement investigations of segmentation processes in other panarthropods and paleontological studies to illuminate the earliest steps in the evolution of panarthropod body plans. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hidroxyapatite Coating on CoCrMo Alloy Titanium Nitride Coated Using Biomimetic Method

NASA Astrophysics Data System (ADS)

Charlena; Sukaryo, S. G.; Fajar, M.

2016-11-01

Bone implants is a way to cure broken bones which is being developed. The implants can be made of metals, ceramics and polymers. Metallic materials commonly used are titanium (Ti), stainless steel, and metal alloys. This study used Co-based alloys, i.e. CoCrMo coated with titanium nitride (TiN) which was then coated on hidroxyapatite (HAp). The HAp coating on the surface of CoCrMo alloy was done by biomimetic methods, first by soaking the metal alloys in simulated body fluid (SBF) solution for 18, 24, and 36 hours. The immersion in the SBF solution produced white coat on the surface of the metal alloy. The layers formed were analyzed by scanning electron microscope (SEM) and characterized by x-ray diffractometer (XRD). Based on the SEM results of 36 hours treatment, the morphology of apatite crystal formed fine grains. According to XRD result, there were HAp peaks at angles 2θ 31.86, 32.25, dan 39.48. However, there were also CaCO3 peaks at angles 2θ 29.46, 36.04, and 46.79. It indicated the pure HAp is not yet formed.

Electrophoretic deposition of silicon substituted hydroxyapatite coatings from n-butanol-chloroform mixture.

PubMed

Xiao, Xiu Feng; Liu, Rong Fang; Tang, Xiao Lian

2008-01-01

Silicon Substituted Hydroxyapatite (Si-HA) coatings were prepared on titanium substrates by electrophoretic deposition (EPD). The stability of Si-HA suspension in n-butanol and chloroform mixture has been studied by electricity conductivity and sedimentation test. The microstructure, shear strength and bioactivity in vitro has been tested. The stability of Si-HA suspension containing n-butanol and chloroform mixture as medium is better than that of pure n-butanol as medium. The good adhesion of the particles with the substrate and good cohesion between the particles were obtained in n-butanol and chloroform mixture. Adding triethanolamine (TEA) as additive into the suspension is in favor of the formation of uniform and compact Si-HA coatings on the titanium substrates by EPD. The shear strength of the coatings can reach 20.43 MPa after sintering at 700 degrees C for 2 h, when the volume ratio of n-butanol: chloroform is 2:1 and the concentration of TEA is 15 ml/L. Titanium substrates etched in H(2)O(2)/NH(3) solution help to improve the shear strength of the coatings. After immersion in simulated body fluid for 7 days, Si-HA coatings have the ability to induce the bone-like apatite formation.

Titaniferous magnetite in the layered intrusive complex at Lakathah, Kingdom of Saudi Arabia

USGS Publications Warehouse

Martin, Conrad; Roberts, Ralph Jackson; Stoeser, D.B.

1979-01-01

The Lakathah layered intrusive complex about 90 km east of Qunfudhah contains significant resources of low-grade titanium-bearing rock. The complex is about 10 km in diameter and consists of three principal units: an outer syenite ring, an intermediate diorite-gabbro zone, and a central pyroxenite-hornblendite core. The principal mineralization zone is in the ultramafic core of the complex. The titanium is mainly in titaniferous magnetite, but some is in ilmenite intergrown with magnetite and in the titanium-bearing hornblende, kaersutite. The titaniferous magnetite is in concordant lenses and veinlets and is disseminated throughout the host rock. The lenses and veins range from a few centimeters to 3 m in width and are as much as 50 m long. The layered disseminated bodies contain as much as 25 percent magnetite. Exploratory drilling showed that an area 500 by 1000 m contains titaniferous rock averaging about 6.2 percent TiO2. This mineralized zone contains about 175,000,000 tons per 100 m depth. Material of this grade is not commercial at this time, but may be a future resource. Alluvial deposits along the Red Sea near Al Qunfudhah should be tested for possible deposits of titaniferous sand.

Concept design of robotic modules for needlescopic surgery.

PubMed

Sen, Shin; Harada, Kanako; Hewitt, Zackary; Susilo, Ekawahyu; Kobayashi, Etsuko; Sakuma, Ichiro

2017-08-01

Many minimally invasive surgical procedures and assisting robotic systems have been developed to further minimize the number and size of incisions in the body surface. This paper presents a new idea combining the advantages of modular robotic surgery, single incision laparoscopic surgery and needlescopic surgery. In the proposed concept, modules carrying therapeutic or diagnostic tools are inserted in the abdominal cavity from the navel as in single incision laparoscopic surgery and assembled to 3-mm needle shafts penetrating the abdominal wall. A three degree-of-freedom robotic module measuring 16 mm in diameter and 51 mm in length was designed and prototyped. The performance of the three connected robotic modules was evaluated. A new idea of modular robotic surgery was proposed, and demonstrated by prototyping a 3-DOF robotic module. The performance of the connected robotic modules was evaluated, and the challenges and future work were summarized.

Fabrication of porous titanium scaffold materials by a fugitive filler method.

PubMed

Hong, T F; Guo, Z X; Yang, R

2008-12-01

A clean powder metallurgy route was developed here to produce Ti foams, using a fugitive polymeric filler, polypropylene carbonate (PPC), to create porosities in a metal-polymer compact at the pre-processing stage. The as-produced foams were studied by scanning electron microscopy (SEM), LECO combustion analyses and X-ray diffraction (XRD). Compression tests were performed to assess their mechanical properties. The results show that titanium foams with open pores can be successfully produced by the method. The compressive strength and modulus of the foams decrease with an increasing level of porosity and can be tailored to those of the human bones. After alkali treatment and soaking in a simulated body fluid (SBF) for 3 days, a thin apatite layer was formed along the Ti foam surfaces, which provides favourable bioactive conditions for bone bonding and growth.

Theory for the Emergence of Modularity in Complex Systems

NASA Astrophysics Data System (ADS)

Deem, Michael; Park, Jeong-Man

2013-03-01

Biological systems are modular, and this modularity evolves over time and in different environments. A number of observations have been made of increased modularity in biological systems under increased environmental pressure. We here develop a theory for the dynamics of modularity in these systems. We find a principle of least action for the evolved modularity at long times. In addition, we find a fluctuation dissipation relation for the rate of change of modularity at short times. We discuss a number of biological and social systems that can be understood with this framework. The modularity of the protein-protein interaction network increases when yeast are exposed to heat shock, and the modularity of the protein-protein networks in both yeast and E. coli appears to have increased over evolutionary time. Food webs in low-energy, stressful environments are more modular than those in plentiful environments, arid ecologies are more modular during droughts, and foraging of sea otters is more modular when food is limiting. The modularity of social networks changes over time: stock brokers instant messaging networks are more modular under stressful market conditions, criminal networks are more modular under increased police pressure, and world trade network modularity has decreased

Human-Derived Disturbance Estimation and Compensation (DEC) Method Lends Itself to a Modular Sensorimotor Control in a Humanoid Robot.

PubMed

Lippi, Vittorio; Mergner, Thomas

2017-01-01

The high complexity of the human posture and movement control system represents challenges for diagnosis, therapy, and rehabilitation of neurological patients. We envisage that engineering-inspired, model-based approaches will help to deal with the high complexity of the human posture control system. Since the methods of system identification and parameter estimation are limited to systems with only a few DoF, our laboratory proposes a heuristic approach that step-by-step increases complexity when creating a hypothetical human-derived control systems in humanoid robots. This system is then compared with the human control in the same test bed, a posture control laboratory. The human-derived control builds upon the identified disturbance estimation and compensation (DEC) mechanism, whose main principle is to support execution of commanded poses or movements by compensating for external or self-produced disturbances such as gravity effects. In previous robotic implementation, up to 3 interconnected DEC control modules were used in modular control architectures separately for the sagittal plane or the frontal body plane and successfully passed balancing and movement tests. In this study we hypothesized that conflict-free movement coordination between the robot's sagittal and frontal body planes emerges simply from the physical embodiment, not necessarily requiring a full body control. Experiments were performed in the 14 DoF robot Lucy Posturob (i) demonstrating that the mechanical coupling from the robot's body suffices to coordinate the controls in the two planes when the robot produces movements and balancing responses in the intermediate plane, (ii) providing quantitative characterization of the interaction dynamics between body planes including frequency response functions (FRFs), as they are used in human postural control analysis, and (iii) witnessing postural and control stability when all DoFs are challenged together with the emergence of inter-segmental coordination in squatting movements. These findings represent an important step toward controlling in the robot in future more complex sensorimotor functions such as walking.

Human-Derived Disturbance Estimation and Compensation (DEC) Method Lends Itself to a Modular Sensorimotor Control in a Humanoid Robot

PubMed Central

Lippi, Vittorio; Mergner, Thomas

2017-01-01

The high complexity of the human posture and movement control system represents challenges for diagnosis, therapy, and rehabilitation of neurological patients. We envisage that engineering-inspired, model-based approaches will help to deal with the high complexity of the human posture control system. Since the methods of system identification and parameter estimation are limited to systems with only a few DoF, our laboratory proposes a heuristic approach that step-by-step increases complexity when creating a hypothetical human-derived control systems in humanoid robots. This system is then compared with the human control in the same test bed, a posture control laboratory. The human-derived control builds upon the identified disturbance estimation and compensation (DEC) mechanism, whose main principle is to support execution of commanded poses or movements by compensating for external or self-produced disturbances such as gravity effects. In previous robotic implementation, up to 3 interconnected DEC control modules were used in modular control architectures separately for the sagittal plane or the frontal body plane and successfully passed balancing and movement tests. In this study we hypothesized that conflict-free movement coordination between the robot's sagittal and frontal body planes emerges simply from the physical embodiment, not necessarily requiring a full body control. Experiments were performed in the 14 DoF robot Lucy Posturob (i) demonstrating that the mechanical coupling from the robot's body suffices to coordinate the controls in the two planes when the robot produces movements and balancing responses in the intermediate plane, (ii) providing quantitative characterization of the interaction dynamics between body planes including frequency response functions (FRFs), as they are used in human postural control analysis, and (iii) witnessing postural and control stability when all DoFs are challenged together with the emergence of inter-segmental coordination in squatting movements. These findings represent an important step toward controlling in the robot in future more complex sensorimotor functions such as walking. PMID:28951719

Delivery of Modular Lethality via a Parent-Child Concept

DTIC Science & Technology

2015-02-01

time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the...downrange distance to the target, is the time of flight, is the distance of the thruster force from the body center of gravity, and is...velocity and time of flight can be estimated or measured in flight. These values can be collected in a term, , and the 2 components of lateral

Influent of Borax Decahydrate Composition as Additional Flux into Stoneware Bodies

NASA Astrophysics Data System (ADS)

Bakil, Siti Natrah Abd; Hussin, Rosniza; Bakar Aramjat, Abu

2017-08-01

Stoneware is vitrified, has less porosity and requires high sintering temperature. The influent of borax decahydrate composition at sintering temperature 1050°C and 1150°C on the thermal analysis, fracture surface, linear shrinkage, water absorption and modular of rapture (MOR) were investigated. Rectangular sample were produced by uniaxially pressing at 40MPa. The thermal behavior was determined by thermogravimetric and different thermal analysis (TGA-DTA). The Scanning electron microscopy (SEM) was used for fracture surface analysis. The water absorption (%) of the sample were determined using Archimedes’ method. The experimental result showed that content of borax decahydrate have influent the properties of stoneware bodies.

Titanium recycling in the United States in 2004, chap. Y of Sibley, S.F., ed., Flow studies for recycling metal commodities in the United States

USGS Publications Warehouse

Goonan, Thomas G.

2010-01-01

As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the titanium metal fraction of the titanium economy, which generates and uses titanium metal scrap in its operations. Data for 2004 were selected to demonstrate the titanium flows associated with these operations. This report includes a description of titanium metal supply and demand in the United States to illustrate the extent of titanium recycling and to identify recycling trends. In 2004, U.S. apparent consumption of titanium metal (contained in various titanium-bearing products) was 45,000 metric tons (t) of titanium, which was distributed as follows: 25,000 t of titanium recovered as new scrap, 9,000 t of titanium as titanium metal and titanium alloy products delivered to the U.S. titanium products reservoir, 7,000 t of titanium consumed by steelmaking and other industries, and 4,000 t of titanium contained in unwrought and wrought products exported. Titanium recycling is concentrated within the titanium metals sector of the total titanium market. The titanium market is otherwise dominated by pigment (titanium oxide) products, which generate dissipative losses instead of recyclable scrap. In 2004, scrap (predominantly new scrap) was the source of roughly 54 percent of the titanium metal content of U.S.-produced titanium metal products.

Investigation of static properties of medical alloys Ti-(20-30)Nb-(10-13)Ta-5Zr

NASA Astrophysics Data System (ADS)

Sergienko, K. V.; Sevost’yanov, M. A.; Konushkin, S. V.; Nasakina, E. O.; Baikin, A. S.; Shatova, L. A.; Kolmakov, A. G.

2018-04-01

In the work, static properties of TiNbTaZr titanium alloy were carried out. The search for a NiTi alloy replacement is necessary for medical products to eliminate the negative effects of nickel on the body. Conclusions are drawn about the adequacy of the mechanical properties of the test alloy for use in stent implants.

Focal osteolysis at the junctions of a modular stainless-steel femoral intramedullary nail.

PubMed

Jones, D M; Marsh, J L; Nepola, J V; Jacobs, J J; Skipor, A K; Urban, R M; Gilbert, J L; Buckwalter, J A

2001-04-01

During routine follow-up of patients treated with a three-piece stainless-steel modular femoral nail, osteolysis and periosteal reaction around the modular junctions of some of the nails were noted on radiographs. The purpose of this study was to evaluate the prevalence, etiology, and clinical relevance of these radiographic findings. Forty-four femoral fractures or nonunions in forty-two patients were treated with a modular stainless-steel femoral intramedullary nail. Seventeen nails were excluded, leaving twenty-seven intramedullary nails in twenty-seven patients for this study. All patients had had a femoral diaphyseal fracture; nineteen had had an acute fracture and eight, a nonunion. These twenty-seven patients returned for radiographs, a physical examination, assessment of functional outcomes, assessment of thigh pain with a visual analog scale, determination of serum chromium levels, and nail removal if desired. A control group of sixteen patients treated with a one-piece stainless-steel femoral intramedullary nail was evaluated with use of the same outcome measures and was compared with the group treated with the modular femoral nail with regard to prevalence of thigh pain and serum chromium levels. Twelve modular femoral nails were removed according to the study protocol. The modular nail junctions were analyzed for corrosion products, and histopathologic analysis of tissue specimens from the femoral canal was performed. The twenty-seven patients were seen at a mean of twenty-one months after fracture fixation; twenty-six of the twenty-seven fractures healed. Twenty-three femora had at least one of three types of abnormalities-osteolysis, periosteal reaction, or cortical thickening--localized to one or both modular junctions. Eighteen patients had severe reactions, defined as osteolysis of > or =2 mm, cortical thickening of > or =5 mm, and/or a periosteal reaction (group 1). Nine patients had mild or no reactions (group 2). Serum chromium levels in group 1 (mean, 1.27 ng/ mL; range, 0.34 to 3.12 ng/mL) were twice as high as those in group 2 (mean, 0.53 ng/mL; range, 0.12 to 1.26 ng/mL). However, this difference did not reach significance with the numbers available. The differences in serum chromium levels between group 1 and the control group with a one-piece nail (mean, 0.26 ng/mL; range, 0.015 to 1.25 ng/mL) (p<0.01) and a control group without an implant (mean, 0.05 ng/mL; range, 0.015 to 0.25 ng/ mL) (p<0.01) were significant. The level of thigh pain recorded on the visual analog scale was also significantly different between group 1 and the control group with a one-piece implant (p = 0.03). Retrieved modular nails had signs of fretting corrosion as well as stainless-steel corrosion products adherent to the junction where the osteolysis occurred. Histologic and spectrographic analysis revealed two types of corrosion products that were consistent with stainless-steel within the peri-implant tissue and were associated with a foreign-body granulomatous response. The presence of corrosion products at the taper junctions suggests that particulate debris was a major factor in the etiology of the radiographic findings of osteolysis, periosteal reaction, and cortical thickening. Serum chromium levels were substantially elevated in the patients with a modular femoral nail, and such levels may serve as a marker of fretting corrosion of these devices.

M3BA: A Mobile, Modular, Multimodal Biosignal Acquisition Architecture for Miniaturized EEG-NIRS-Based Hybrid BCI and Monitoring.

PubMed

von Luhmann, Alexander; Wabnitz, Heidrun; Sander, Tilmann; Muller, Klaus-Robert

2017-06-01

For the further development of the fields of telemedicine, neurotechnology, and brain-computer interfaces, advances in hybrid multimodal signal acquisition and processing technology are invaluable. Currently, there are no commonly available hybrid devices combining bioelectrical and biooptical neurophysiological measurements [here electroencephalography (EEG) and functional near-infrared spectroscopy (NIRS)]. Our objective was to design such an instrument in a miniaturized, customizable, and wireless form. We present here the design and evaluation of a mobile, modular, multimodal biosignal acquisition architecture (M3BA) based on a high-performance analog front-end optimized for biopotential acquisition, a microcontroller, and our openNIRS technology. The designed M3BA modules are very small configurable high-precision and low-noise modules (EEG input referred noise @ 500 SPS 1.39 μV pp , NIRS noise equivalent power NEP 750 nm = 5.92 pW pp , and NEP 850 nm = 4.77 pW pp ) with full input linearity, Bluetooth, 3-D accelerometer, and low power consumption. They support flexible user-specified biopotential reference setups and wireless body area/sensor network scenarios. Performance characterization and in-vivo experiments confirmed functionality and quality of the designed architecture. Telemedicine and assistive neurotechnology scenarios will increasingly include wearable multimodal sensors in the future. The M3BA architecture can significantly facilitate future designs for research in these and other fields that rely on customized mobile hybrid biosignal modal biosignal acquisition architecture (M3BA), multimodal, near-infrared spectroscopy (NIRS), wireless body area network (WBAN), wireless body sensor network (WBSN).

The functional architecture of the human body: assessing body representation by sorting body parts and activities.

PubMed

Bläsing, Bettina; Schack, Thomas; Brugger, Peter

2010-05-01

We investigated mental representations of body parts and body-related activities in two subjects with congenitally absent limbs (one with, the other without phantom sensations), a wheelchair sports group of paraplegic participants, and two groups of participants with intact limbs. To analyse mental representation structures, we applied Structure Dimensional Analysis. Verbal labels indicating body parts and related activities were presented in randomized lists that had to be sorted according to a hierarchical splitting paradigm. Participants were required to group the items according to whether or not they were considered related, based on their own body perception. Results of the groups of physically intact and paraplegic participants revealed separate clusters for the lower body, upper body, fingers and head. The participant with congenital phantom limbs also showed a clear separation between upper and lower body (but not between fingers and hands). In the participant without phantom sensations of the absent arms, no such modularity emerged, but the specific practice of his right foot in communication and daily routines was reflected. Sorting verbal labels of body parts and activities appears a useful method to assess body representation in individuals with special body anatomy or function and leads to conclusions largely compatible with other assessment procedures.

Survey of Modular Military Vehicles: Benefits and Burdens

DTIC Science & Technology

2016-01-01

Survey of Modular Military Vehicles: BENEFITS and BURDENS Jean M. Dasch and David J. Gorsich Modularity in military vehicle design is generally...considered a positive attribute that promotes adaptability, resilience, and cost savings. The benefits and burdens of modularity are considered by...Engineering Center, vehicles were considered based on horizontal modularity , vertical modularity , and distributed modularity . Examples were given for each

Can modular psychological concepts like affect and emotion be assigned to a distinct subset of regional neural circuits?. Comment on "The quartet theory of human emotions: An integrative and neurofunctional model" by S. Koelsch et al.

NASA Astrophysics Data System (ADS)

Fehr, Thorsten; Herrmann, Manfred

2015-06-01

The proposed Quartet Theory of Human Emotions by Koelsch and co-workers [11] adumbrates evidence from various scientific sources to integrate and assign the psychological concepts of 'affect' and 'emotion' to four brain circuits or to four neuronal core systems for affect-processing in the brain. The authors differentiate between affect and emotion and assign several facultative, or to say modular, psychological domains and principles of information processing, such as learning and memory, antecedents of affective activity, emotion satiation, cognitive complexity, subjective quality feelings, degree of conscious appraisal, to different affect systems. Furthermore, they relate orbito-frontal brain structures to moral affects as uniquely human, and the hippocampus to attachment-related affects. An additional feature of the theory describes 'emotional effector-systems' for motor-related processes (e.g., emotion-related actions), physiological arousal, attention and memory that are assumed to be cross-linked with the four proposed affect systems. Thus, higher principles of emotional information processing, but also modular affect-related issues, such as moral and attachment related affects, are thought to be handled by these four different physiological sub-systems that are on the other side assumed to be highly interwoven at both physiological and functional levels. The authors also state that the proposed sub-systems have many features in common, such as the selection and modulation of biological processes related to behaviour, perception, attention and memory. The latter aspect challenges an ongoing discussion about the mind-body problem: To which degree do the proposed sub-systems 'sufficiently' cover the processing of complex modular or facultative emotional/affective and/or cognitive phenomena? There are current models and scientific positions that almost completely reject the idea that modular psychological phenomena are handled by a distinct selection of regional brain systems or neural modules, but rather suggest highly complex and cross-linked neural networks individually shaped by livelong learning and experience [e.g., 6,7,10,13]. This holds in particular true for complex emotional phenomena such as aggression or empathy in social interaction [8,13]. It thus remains questionable, whether - beyond primary sensory and motor-processing - a small number of modular sub-systems sufficiently cover the organisation of specific phenomenological and social features of perception and behaviour [7,10].

STRATIFIED COMPOSITION EFFECTS ON PLANETARY NEUTRON FLUX

DOE Office of Scientific and Technical Information (OSTI.GOV)

O. GASNAULT; ET AL

2001-01-01

All the bodies of the solar system that are directly irradiated by the galactic cosmic rays, emit enough neutrons to allow a measurement from space. These leakage neutron fluxes are indexes of the surface composition, depending on the energy of the neutrons [1]. Recent work propose geochemical interpretations of these fluxes: the thermal energy range is sensitive to iron, titanium, rare earth elements and thorium [2, 3], the epithermal energy range is sensitive to hydrogen, samarium and gadolinium [2] and the fast energy range is representative of the average soil atomic mass [4]. Nevertheless these studies make the hypothesis ofmore » a composition uniform within the footprint of the spectrometer and independent of depth. We show in this abstract that a stratified composition could change significantly the flux intensity and complicate the interpretation of the measurements. The neutron leakage flux is a competition between production effects (sensitive at high energy) and diffusion-capture effects (mostly sensitive at low energy). On one hand, it happens to be that the elements which produce the higher number of neutrons in typical lunar compositions are iron and titanium, which have also large cross section of absorption with the neutrons. On the other hand, the maximum of neutron intensity does not occur at the surface but at about 180 g cm{sup {minus}2} in depth. Therefore, if we have an iron- and/or titanium-rich soil (important production of neutrons) with a top layer having less iron and/or titanium (i.e. more transparent to the neutrons), we can expect an enhancement of the flux compared to a uniform composition.« less

The effect of plasma surface treatment on the bioactivity of titanium implant materials (in vitro)

PubMed Central

Abdelrahim, Ramy A.; Badr, Nadia A.; Baroudi, Kusai

2016-01-01

Background: The surface of an implantable biomaterial plays a very important role in determining the biocompatibility, osteoinduction, and osteointegration of implants because it is in intimate contact with the host bone and soft tissues. Objective: This study was aimed to assess the effect of plasma surface treatment on the bioactivity of titanium alloy (Ti–6Al–4V). Materials and Methods: Fifteen titanium alloy samples were used in this study. The samples were divided into three groups (with five samples in each group). Five samples were kept untreated and served as control (group A). Another five plasma samples were sprayed for nitrogen ion implantation on their surfaces (group B) and the last five samples were pre-etched with acid before plasma treatment (group C). All the investigated samples were immersed for 7 days in Hank's balanced salt solution (HBSS) which was used as a simulating body fluid (SBF) at pH 7.4 and 37°C. HBSS was renewed every 3 days. The different surfaces were characterized by X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDXA), and Fourier Transformation Infrared Spectroscopy (FTIR). Results: Nitriding of Ti-alloy samples via plasma nitrogen ion implantation increased the bioactivity of titanium. Moreover, the surface topography affected the chemical structure of the formed apatite. Increasing the surface roughness enhanced the bioactivity of the implant material. Conclusions: Nitridation can be exploited as an effective way to promote the formation of bone-like material on the implant surface. PMID:27011927

NASA Ames potential flow analysis (POTFAN) geometry program (POTGEM), version 1

NASA Technical Reports Server (NTRS)

Medan, R. T.; Bullock, R. B.

1976-01-01

A computer program known as POTGEM is reported which has been developed as an independent segment of a three-dimensional linearized, potential flow analysis system and which is used to generate a panel point description of arbitrary, three-dimensional bodies from convenient engineering descriptions consisting of equations and/or tables. Due to the independent, modular nature of the program, it may be used to generate corner points for other computer programs.

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

DOEpatents

Koc, Rasit; Glatzmaier, Gregory C.

1995-01-01

A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

DOEpatents

Koc, R.; Glatzmaier, G.C.

1995-05-23

A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

Phase Stability and Stress-Induced Transformations in Beta Titanium Alloys

NASA Astrophysics Data System (ADS)

Kolli, R. Prakash; Joost, William J.; Ankem, Sreeramamurthy

2015-06-01

In this article, we provide a brief review of the recent developments related to the relationship between phase stability and stress-induced transformations in metastable body-centered-cubic β-phase titanium alloys. Stress-induced transformations occur during tensile, compressive, and creep loading and influence the mechanical response. These transformations are not fully understood and increased understanding of these mechanisms will permit future development of improved alloys for aerospace, biomedical, and energy applications. In the first part of this article, we review phase stability and discuss a few recent developments. In the second section, we discuss the current status of understanding stress-induced transformations and several areas that require further study. We also provide our perspective on the direction of future research efforts. Additionally, we address the occurrence of the hcp ω-phase and the orthorhombic α″-martensite phase stress-induced transformations.

Whole-body concentrations of elements in three fish species from offshore oil platforms and natural areas in the Southern California Bight, USA

USGS Publications Warehouse

Love, Milton S.; Saiki, Michael K.; May, Thomas W.; Yee, Julie L.

2013-01-01

elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.

Enhancement of bioactivity of titanium carbonitride nanocomposite thin films on steels with biosynthesized hydroxyapatite

PubMed Central

Thampi, VV Anusha; Dhandapani, P; Manivasagam, Geetha; Subramanian, B

2015-01-01

Thin films of titanium carbonitride (TiCN) were fabricated by DC magnetron sputtering on medical grade steel. The biocompatibility of the coating was further enhanced by growing hydroxyapatite crystals over the TiCN-coated substrates using biologically activated ammonia from synthetic urine. The coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM)-energy dispersive spectroscopy, and Raman spectroscopy. The electrochemical behavior of the coatings was determined in simulated body fluid. In addition, hemocompatibility was assessed by monitoring the attachment of platelets on the coating using SEM. The wettability of the coatings was measured in order to correlate with biocompatibility results. Formation of a coating with granular morphology and the preferred orientation was confirmed by SEM and X-ray diffraction results. The hydroxyapatite coating led to a decrease in thrombogenicity, resulting in controlled blood clot formation, hence demonstrating the hemocompatibility of the coating. PMID:26491312

A new Ti-5Ag alloy for customized prostheses by three-dimensional printing (3DP).

PubMed

Hong, S B; Eliaz, N; Leisk, G G; Sach, E M; Latanision, R M; Allen, S M

2001-03-01

Three important considerations in the fabrication of customized cranio-maxillofacial prostheses are geometric precision, material strength, and biocompatibility. Three-dimensional printing (3DP) is a rapid part-fabrication process that can produce complex parts with high precision. The aim of this study was to design, synthesize by 3DP, and characterize a new Ti-5Ag (wt%) alloy. Silver nitrate was found to be an appropriate inorganic binder for the Ti powder-based skeleton, and the optimum sintering parameters for full densification were determined. The hardness of the Ti-5Ag alloy was shown to be much higher than that of a pure titanium sample. Potentiodynamic measurements, carried out in saline solution at body temperature, showed that the Ti-5Ag alloy had good passivation behavior, similar to that of pure titanium. It is concluded that the Ti-Ag system may be suitable for fabrication of customized prostheses by 3DP.

Bio-camouflage of anatase nanoparticles explored by in situ high-resolution electron microscopy.

PubMed

Ribeiro, Ana R; Mukherjee, Arijita; Hu, Xuan; Shafien, Shayan; Ghodsi, Reza; He, Kun; Gemini-Piperni, Sara; Wang, Canhui; Klie, Robert F; Shokuhfar, Tolou; Shahbazian-Yassar, Reza; Borojevic, Radovan; Rocha, Luis A; Granjeiro, José M

2017-08-03

While titanium is the metal of choice for most prosthetics and inner body devices due to its superior biocompatibility, the discovery of Ti-containing species in the adjacent tissue as a result of wear and corrosion has been associated with autoimmune diseases and premature implant failures. Here, we utilize the in situ liquid cell transmission electron microscopy (TEM) in a liquid flow holder and graphene liquid cells (GLCs) to investigate, for the first time, the in situ nano-bio interactions between titanium dioxide nanoparticles and biological medium. This imaging and spectroscopy methodology showed the process of formation of an ionic and proteic bio-camouflage surrounding Ti dioxide (anatase) nanoparticles that facilitates their internalization by bone cells. The in situ understanding of the mechanisms of the formation of the bio-camouflage of anatase nanoparticles may contribute to the definition of strategies aimed at the manipulation of these NPs for bone regenerative purposes.

Enhancement of bioactivity of titanium carbonitride nanocomposite thin films on steels with biosynthesized hydroxyapatite.

PubMed

Thampi, V V Anusha; Dhandapani, P; Manivasagam, Geetha; Subramanian, B

2015-01-01

Thin films of titanium carbonitride (TiCN) were fabricated by DC magnetron sputtering on medical grade steel. The biocompatibility of the coating was further enhanced by growing hydroxyapatite crystals over the TiCN-coated substrates using biologically activated ammonia from synthetic urine. The coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM)-energy dispersive spectroscopy, and Raman spectroscopy. The electrochemical behavior of the coatings was determined in simulated body fluid. In addition, hemocompatibility was assessed by monitoring the attachment of platelets on the coating using SEM. The wettability of the coatings was measured in order to correlate with biocompatibility results. Formation of a coating with granular morphology and the preferred orientation was confirmed by SEM and X-ray diffraction results. The hydroxyapatite coating led to a decrease in thrombogenicity, resulting in controlled blood clot formation, hence demonstrating the hemocompatibility of the coating.

The effects of a SiO2 coating on the corrosion parameters cpTi and Ti-6Al-7Nb alloy

PubMed Central

Basiaga, Marcin; Walke, Witold; Paszenda, Zbigniew; Karasiński, Paweł; Szewczenko, Janusz

2014-01-01

The aim of this paper was to evaluate the usefulness of the sol-gel method application, to modificate the surface of the Ti6Al7Nb alloy and the cpTi titanium (Grade 4) with SiO2 oxide, applied on the vascular implants to improve their hemocompatibility. Mechanical treatment was followed by film deposition on surface of the titanium samples. An appropriate selection of the process parameters was verified in the studies of corrosion, using potentiodynamic and impedance method. A test was conducted in the solution simulating blood vessels environment, in simulated body fluid at t = 37.0 ± 1 °C and pH = 7.0 ± 0.2. Results showed varied electrochemical properties of the SiO2 film, depending on its deposition parameters. Correlations between corrosion resistance and layer adhesion to the substrate were observed, depending on annealing temperature. PMID:25482412

Fullerene-like Polyoxotitanium Cage with High Solution Stability.

PubMed

Gao, Mei-Yan; Wang, Fei; Gu, Zhi-Gang; Zhang, De-Xiang; Zhang, Lei; Zhang, Jian

2016-03-02

We present the formation of the largest titanium-oxo cluster, [Ti42(μ3-O)60(OiPr)42(OH)12)](6-), with the first fullerene-like Ti-O shell structure. The {Ti42O60} core of this compound exemplifies the same icosahedral (Ih) symmetry as C60, the highest possible symmetry for molecules. According to the coordination environments, the Ti centers in this cluster can be arranged into a Platonic {Ti12} icosahedron and an Archimedean {Ti30} icosidodecahedron. The solution stability of this cluster was confirmed by electrospray ionization mass spectrometry. The spherical body of the {Ti42O60} core has an inside diameter of 1.05 nm and an outside diameter of 1.53 nm, which could be directly visualized by high-resolution transmission electron microscopy. Our results demonstrate that titanium oxide can also form fullerene-like shell structures.

Laser cladding of bioactive glass coatings.

PubMed

Comesaña, R; Quintero, F; Lusquiños, F; Pascual, M J; Boutinguiza, M; Durán, A; Pou, J

2010-03-01

Laser cladding by powder injection has been used to produce bioactive glass coatings on titanium alloy (Ti6Al4V) substrates. Bioactive glass compositions alternative to 45S5 Bioglass were demonstrated to exhibit a gradual wetting angle-temperature evolution and therefore a more homogeneous deposition of the coating over the substrate was achieved. Among the different compositions studied, the S520 bioactive glass showed smoother wetting angle-temperature behavior and was successfully used as precursor material to produce bioactive coatings. Coatings processed using a Nd:YAG laser presented calcium silicate crystallization at the surface, with a uniform composition along the coating cross-section, and no significant dilution of the titanium alloy was observed. These coatings maintain similar bioactivity to that of the precursor material as demonstrated by immersion in simulated body fluid. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fretting and Corrosion Between a Metal Shell and Metal Liner May Explain the High Rate of Failure of R3 Modular Metal-on-Metal Hips.

PubMed

Ilo, Kevin C; Derby, Emma J; Whittaker, Robert K; Blunn, Gordon W; Skinner, John A; Hart, Alister J

2017-05-01

The R3 acetabular system used with its metal liner has higher revision rates when compared to its ceramic and polyethylene liner. In June 2012, the medical and healthcare products regulatory agency issued an alert regarding the metal liner of the R3 acetabular system. Six retrieved R3 acetabular systems with metal liners underwent detailed visual analysis using macroscopic and microscopic techniques. Visual analysis discovered corrosion on the backside of the metal liners. There was a distinct border to the areas of corrosion that conformed to antirotation tab insertions on the inner surface of the acetabular shell, which are for the polyethylene liner. Scanning electron microscopy indicated evidence of crevice corrosion, and energy-dispersive X-ray analysis confirmed corrosion debris rich in titanium. The high failure rate of the metal liner option of the R3 acetabular system may be attributed to corrosion on the backside of the liner which appear to result from geometry and design characteristics of the acetabular shell. Copyright © 2016 Elsevier Inc. All rights reserved.

Automated Modular Magnetic Resonance Imaging Clinical Decision Support System (MIROR): An Application in Pediatric Cancer Diagnosis.

PubMed

Zarinabad, Niloufar; Meeus, Emma M; Manias, Karen; Foster, Katharine; Peet, Andrew

2018-05-02

Advances in magnetic resonance imaging and the introduction of clinical decision support systems has underlined the need for an analysis tool to extract and analyze relevant information from magnetic resonance imaging data to aid decision making, prevent errors, and enhance health care. The aim of this study was to design and develop a modular medical image region of interest analysis tool and repository (MIROR) for automatic processing, classification, evaluation, and representation of advanced magnetic resonance imaging data. The clinical decision support system was developed and evaluated for diffusion-weighted imaging of body tumors in children (cohort of 48 children, with 37 malignant and 11 benign tumors). Mevislab software and Python have been used for the development of MIROR. Regions of interests were drawn around benign and malignant body tumors on different diffusion parametric maps, and extracted information was used to discriminate the malignant tumors from benign tumors. Using MIROR, the various histogram parameters derived for each tumor case when compared with the information in the repository provided additional information for tumor characterization and facilitated the discrimination between benign and malignant tumors. Clinical decision support system cross-validation showed high sensitivity and specificity in discriminating between these tumor groups using histogram parameters. MIROR, as a diagnostic tool and repository, allowed the interpretation and analysis of magnetic resonance imaging images to be more accessible and comprehensive for clinicians. It aims to increase clinicians' skillset by introducing newer techniques and up-to-date findings to their repertoire and make information from previous cases available to aid decision making. The modular-based format of the tool allows integration of analyses that are not readily available clinically and streamlines the future developments. ©Niloufar Zarinabad, Emma M Meeus, Karen Manias, Katharine Foster, Andrew Peet. Originally published in JMIR Medical Informatics (http://medinform.jmir.org), 02.05.2018.

Implantable devices having ceramic coating applied via an atomic layer deposition method

DOEpatents

Liang, Xinhua; Weimer, Alan W.; Bryant, Stephanie J.

2016-03-08

Substrates coated with films of a ceramic material such as aluminum oxides and titanium oxides are biocompatible, and can be used in a variety of applications in which they are implanted in a living body. The substrate is preferably a porous polymer, and may be biodegradable. An important application for the ceramic-coated substrates is as a tissue engineering scaffold for forming artificial tissue.

The relative efficiency of modular and non-modular networks of different size

PubMed Central

Tosh, Colin R.; McNally, Luke

2015-01-01

Most biological networks are modular but previous work with small model networks has indicated that modularity does not necessarily lead to increased functional efficiency. Most biological networks are large, however, and here we examine the relative functional efficiency of modular and non-modular neural networks at a range of sizes. We conduct a detailed analysis of efficiency in networks of two size classes: ‘small’ and ‘large’, and a less detailed analysis across a range of network sizes. The former analysis reveals that while the modular network is less efficient than one of the two non-modular networks considered when networks are small, it is usually equally or more efficient than both non-modular networks when networks are large. The latter analysis shows that in networks of small to intermediate size, modular networks are much more efficient that non-modular networks of the same (low) connective density. If connective density must be kept low to reduce energy needs for example, this could promote modularity. We have shown how relative functionality/performance scales with network size, but the precise nature of evolutionary relationship between network size and prevalence of modularity will depend on the costs of connectivity. PMID:25631996

Production of Titanium Metal by an Electrochemical Molten Salt Process

NASA Astrophysics Data System (ADS)

Fatollahi-Fard, Farzin

Titanium production is a long and complicated process. What we often consider to be the standard method of primary titanium production (the Kroll process), involves many complex steps both before and after to make a useful product from titanium ore. Thus new methods of titanium production, especially electrochemical processes, which can utilize less-processed feedstocks have the potential to be both cheaper and less energy intensive than current titanium production processes. This project is investigating the use of lower-grade titanium ores with the electrochemical MER process for making titanium via a molten salt process. The experimental work carried out has investigated making the MER process feedstock (titanium oxycarbide) with natural titanium ores--such as rutile and ilmenite--and new ways of using the MER electrochemical reactor to "upgrade" titanium ores or the titanium oxycarbide feedstock. It is feasible to use the existing MER electrochemical reactor to both purify the titanium oxycarbide feedstock and produce titanium metal.

Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

NASA Astrophysics Data System (ADS)

Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

2016-02-01

The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications.

PubMed

Gordin, D M; Busardo, D; Cimpean, A; Vasilescu, C; Höche, D; Drob, S I; Mitran, V; Cornen, M; Gloriant, T

2013-10-01

In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

PubMed

Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

2007-01-01

Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications. 2006 Wiley Periodicals, Inc.

Effects of oral administration of titanium dioxide fine-sized particles on plasma glucose in mice.

PubMed

Gu, Ning; Hu, Hailong; Guo, Qian; Jin, Sanli; Wang, Changlin; Oh, Yuri; Feng, Yujie; Wu, Qiong

2015-12-01

Titanium dioxide (TiO2) is an authorized additive used as a food colorant, is composed of nano-sized particles (NP) and fine-sized particles (FP). Previous study reported that oral administration of TiO2 NPs triggers an increase in plasma glucose of mice. However, no previous studies have focused on toxic effects of TiO2 FPs on plasma glucose homeostasis following oral administration. In the current study, mice were orally administered TiO2 FPs greater than 100 nm in size (64 mg/kg body weight per day), and effects on plasma glucose levels examined. Our results showed that titanium levels was not changed in mouse blood, livers and pancreases after mice were orally administered TiO2 FPs. Biochemical analyzes showed that plasma glucose and ROS levels were not affected by TiO2 FPs. Histopathological results showed that TiO2 FPs did not induce pathology changes in organs, especially plasma glucose homeostasis regulation organs, such as pancreas and liver. Western blotting showed that oral administration of TiO2 FPs did not induce insulin resistance (IR) in mouse liver. These results showed that, TiO2 FPs cannot be absorbed via oral administration and affect plasma glucose levels in mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

NASA Astrophysics Data System (ADS)

Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

2016-05-01

Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

Structure, apatite inducing ability, and corrosion behavior of chitosan/halloysite nanotube coatings prepared by electrophoretic deposition on titanium substrate.

PubMed

Molaei, A; Amadeh, A; Yari, M; Reza Afshar, M

2016-02-01

In this study chitosan/halloysite nanotube composite (CS/HNT) coatings were deposited by electrophoretic deposition (EPD) on titanium substrate. Using HNT particles were investigated as new substituents for carbon nanotubes (CNTs) in chitosan matrix coatings. The ability of chitosan as a stabilizing, charging, and blending agent for HNT particles was exploited. Furthermore, the effects of pH, electrophoretic bath, and sonicating duration were studied on the deposition of suspensions containing HNT particles. Microstructure properties of coatings showed uniform distribution of HNT particles in chitosan matrix to form smooth nanocomposite coatings. The zeta potential results revealed that at pH around 3 there is an isoelectric point for HNT and it would have cathodic and anionic states at pH values less and more than 3, respectively. Therefore, CS/HNT composite deposits were produced in the pH range of 2.5 to 3. The apatite inducing ability of chitosan-HNT composite coating assigned that HNT particles were biocompatible because they formed carbonated hydroxyapatite particles on CS/HNT coating in corrected simulated body fluid (C-SBF). Finally, electrochemical corrosion characterizations determined that corrosion resistance in CS/HNT coating has been improved compared to bare titanium substrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of nanostructured porous silica coatings on titanium and their cell adhesive and osteogenic differentiation properties.

PubMed

Inzunza, Débora; Covarrubias, Cristian; Von Marttens, Alfredo; Leighton, Yerko; Carvajal, Juan Carlos; Valenzuela, Francisco; Díaz-Dosque, Mario; Méndez, Nicolás; Martínez, Constanza; Pino, Ana María; Rodríguez, Juan Pablo; Cáceres, Mónica; Smith, Patricio

2014-01-01

Nanostructured porous silica coatings were synthesized on titanium by the combined sol-gel and evaporation-induced self-assembly process. The silica-coating structures were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen sorptometry. The effect of the nanoporous surface on apatite formation in simulated body fluid, protein adsorption, osteoblast cell adhesion behavior, and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) is reported. Silica coatings with highly ordered sub-10 nm porosity accelerate early osteoblast adhesive response, a favorable cell response that is attributed to an indirect effect due to the high protein adsorption observed on the large-specific surface area of the nanoporous coating but is also probably due to direct mechanical stimulus from the nanostructured topography. The nanoporous silica coatings, particularly those doped with calcium and phosphate, also promote the osteogenic differentiation of hBMSCs with spontaneous mineral nodule formation in basal conditions. The bioactive surface properties exhibited by the nanostructured porous silica coatings make these materials a promising alternative to improve the osseointegration properties of titanium dental implants and could have future impact on the nanoscale design of implant surfaces. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

The EXPERT project: part of the Super-FRS Experiment Collaboration

NASA Astrophysics Data System (ADS)

Chudoba, V.; "EXPERT project, Flexture plate motion-transfer mechanism, beam-splitter assembly, and interferometer incorporating the same

DOEpatents

Carangelo, R.M.; Dettori, M.D.; Grigely, L.J.; Murray, T.C.; Solomon, P.R.; Dine, C.P. Van; Wright, D.D.

1996-01-23

A multiplicity of one-piece flexure plates are assembled in pairs to provide a support system on which a retroreflector may be mounted for reciprocal motion. Combined with balance bodies, the flexure plates provide a support system having portions that are dynamically and statically balanced with one another, irrespective of orientation, so as to thereby immunize the unit against extraneous forces. The motion transfer assembly is especially adapted for use to support a moving retroreflector in a two-arm interferometer that may further include a beamsplitter assembly constructed from a one-piece, integrally formed body, the body having convergent, optically flat planar surfaces of specular reflectance, and means for adjustably mounting a beamsplitter therein. The spectrometer is of modular construction, and employs an integrated clocking sub-assembly as well as a light-weight voice-coil motor. 15 figs.

Flexture plate motion-transfer mechanism, beam-splitter assembly, and interferometer incorporating the same

DOEpatents

Carangelo, Robert M.; Dettori, Mark D.; Grigely, Lawrence J.; Murray, Terence C.; Solomon, Peter R.; Van Dine, C. Peter; Wright, David D.

1996-01-01

A multiplicity of one-piece flexure plates are assembled in pairs to provide a support system on which a retroreflector may be mounted for reciprocal motion. Combined with balance bodies, the flexure plates provide a support system having portions that are dynamically and statically balanced with one another, irrespective of orientation, so as to thereby immunize the unit against extraneous forces. The motion transfer assembly is especially adapted for use to support a moving retroreflector in a two-arm interferometer that may further include a beamsplitter assembly constructed from a one-piece, integrally formed body, the body having convergent, optically flat planar surfaces of specular reflectance, and means for adjustably mounting a beamsplitter therein. The spectrometer is of modular construction, and employs an integrated clocking sub-assembly as well as a light-weight voice-coil motor.

Tensile properties of titanium electrolytically charged with hydrogen

NASA Technical Reports Server (NTRS)

Smith, R. J.; Otterson, D. A.

1971-01-01

Yield strength, ultimate tensile strength, and elongation were studied for annealed titanium electrolytically charged with hydrogen. The hydrogen was present as a surface hydride layer. These tensile properties were generally lower for uncharged titanium than for titanium with a continuous surface hydride; they were greater for uncharged titanium than for titanium with an assumed discontinuous surface hydride. We suggest that the interface between titanium and titanium hydride is weak. And the hydride does not necessarily impair strength and ductility of annealed titanium. The possibility that oxygen and/or nitrogen can embrittle titanium hydride is discussed.

Adaptive multi-resolution Modularity for detecting communities in networks

NASA Astrophysics Data System (ADS)

Chen, Shi; Wang, Zhi-Zhong; Bao, Mei-Hua; Tang, Liang; Zhou, Ji; Xiang, Ju; Li, Jian-Ming; Yi, Chen-He

2018-02-01

Community structure is a common topological property of complex networks, which attracted much attention from various fields. Optimizing quality functions for community structures is a kind of popular strategy for community detection, such as Modularity optimization. Here, we introduce a general definition of Modularity, by which several classical (multi-resolution) Modularity can be derived, and then propose a kind of adaptive (multi-resolution) Modularity that can combine the advantages of different Modularity. By applying the Modularity to various synthetic and real-world networks, we study the behaviors of the methods, showing the validity and advantages of the multi-resolution Modularity in community detection. The adaptive Modularity, as a kind of multi-resolution method, can naturally solve the first-type limit of Modularity and detect communities at different scales; it can quicken the disconnecting of communities and delay the breakup of communities in heterogeneous networks; and thus it is expected to generate the stable community structures in networks more effectively and have stronger tolerance against the second-type limit of Modularity.

Product modular design incorporating preventive maintenance issues

NASA Astrophysics Data System (ADS)

Gao, Yicong; Feng, Yixiong; Tan, Jianrong

2016-03-01

Traditional modular design methods lead to product maintenance problems, because the module form of a system is created according to either the function requirements or the manufacturing considerations. For solving these problems, a new modular design method is proposed with the considerations of not only the traditional function related attributes, but also the maintenance related ones. First, modularity parameters and modularity scenarios for product modularity are defined. Then the reliability and economic assessment models of product modularity strategies are formulated with the introduction of the effective working age of modules. A mathematical model used to evaluate the difference among the modules of the product so that the optimal module of the product can be established. After that, a multi-objective optimization problem based on metrics for preventive maintenance interval different degrees and preventive maintenance economics is formulated for modular optimization. Multi-objective GA is utilized to rapidly approximate the Pareto set of optimal modularity strategy trade-offs between preventive maintenance cost and preventive maintenance interval difference degree. Finally, a coordinate CNC boring machine is adopted to depict the process of product modularity. In addition, two factorial design experiments based on the modularity parameters are constructed and analyzed. These experiments investigate the impacts of these parameters on the optimal modularity strategies and the structure of module. The research proposes a new modular design method, which may help to improve the maintainability of product in modular design.

Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys

NASA Technical Reports Server (NTRS)

Gray, H. R.

1975-01-01

Tensile and creep properties of experimental beta-titanium alloys were determined. Titanium-vanadium alloys had substantially greater tensile and creep strength than the titanium-niobium and titanium-molybdenum alloys tested. Specific tensile strengths of several titanium-vanadium-aluminum-silicon alloys were equivalent or superior to those of commercial titanium alloys to temperatures of 650 C. The Ti-50V-3Al-1Si alloy had the best balance of tensile strength, creep strength, and metallurgical stability. Its 500 C creep strength was far superior to that of a widely used commercial titanium alloy, Ti-6Al-4V, and almost equivalent to that of newly developed commercial titanium alloys.

Using a network modularity analysis to inform management of a rare endemic plant in the northern Great Plains, USA

USGS Publications Warehouse

Larson, Diane L.; Droege, Sam; Rabie, Paul A.; Larson, Jennifer L.; Devalez, Jelle; Haar, Milton; McDermott-Kubeczko, Margaret

2014-01-01

1. Analyses of flower-visitor interaction networks allow application of community-level information to conservation problems, but management recommendations that ensue from such analyses are not well characterized. Results of modularity analyses, which detect groups of species (modules) that interact more with each other than with species outside their module, may be particularly applicable to management concerns. 2. We conducted modularity analyses of networks surrounding a rare endemic annual plant, Eriogonum visheri, at Badlands National Park, USA, in 2010 and 2011. Plant species visited were determined by pollen on insect bodies and by flower species upon which insects were captured. Roles within modules (network hub, module hub, connector and peripheral, in decreasing order of network structural importance) were determined for each species. 3. Relationships demonstrated by the modularity analysis, in concert with knowledge of pollen species carried by insects, allowed us to infer effects of two invasive species on E. visheri. Sharing a module increased risk of interspecific pollen transfer to E. visheri. Control of invasive Salsola tragus, which shared a module with E. visheri, is therefore a prudent management objective, but lack of control of invasive Melilotus officinalis, which occupied a different module, is unlikely to negatively affect pollination of E. visheri. Eriogonum pauciflorum may occupy a key position in this network, supporting insects from the E. visheri module when E. visheri is less abundant. 4. Year-to-year variation in species' roles suggests management decisions must be based on observations over several years. Information on pollen deposition on stigmas would greatly strengthen inferences made from the modularity analysis. 5. Synthesis and applications: Assessing the consequences of pollination, whether at the community or individual level, is inherently time-consuming. A trade-off exists: rather than an estimate of fitness effects, the network approach provides a broad understanding of the relationships among insect visitors and other plant species that may affect the focal rare plant. Knowledge of such relationships allows managers to detect, target and prioritize control of only the important subset of invasive species present and identify other species that may augment a rare species' population stability, such as E. pauciflorum in our study.

Modularity of a leaf moth-wing pattern and a versatile characteristic of the wing-pattern ground plan

PubMed Central

2013-01-01

Background One of the most intriguing questions in evolutionary developmental biology is how an insect acquires a mimicry pattern within its body parts. A striking example of pattern mimicry is found in the pattern diversity of moth and butterfly wings, which is thought to evolve from preexisting elements illustrated by the nymphalid ground plan (NGP). Previous studies demonstrated that individuality of the NGP facilitates the decoupling of associated common elements, leading to divergence. In contrast, recent studies on the concept of modularity have argued the importance of a combination of coupling and decoupling of the constituent elements. Here, we examine the modularity of a mimicry wing pattern in a moth and explore an evolvable characteristic of the NGP. Results This study examined the wings of the noctuid moth Oraesia excavata, which closely resemble leaves with a leaf venation pattern. Based on a comparative morphological procedure, we found that this leaf pattern was formed by the NGP common elements. Using geometric morphometrics combined with network analysis, we found that each of the modules in the leaf pattern integrates the constituent components of the leaf venation pattern (i.e., the main and lateral veins). Moreover, the detected modules were established by coupling different common elements and decoupling even a single element into different modules. The modules of the O. excavata wing pattern were associated with leaf mimicry, not with the individuality of the NGP common elements. For comparison, we also investigated the modularity of a nonmimetic pattern in the noctuid moth Thyas juno. Quantitative analysis demonstrated that the modules of the T. juno wing pattern regularly corresponded to the individuality of the NGP common elements, unlike those in the O. excavata wing pattern. Conclusions This study provides the first evidence for modularity in a leaf mimicry pattern. The results suggest that the evolution of this pattern involves coupling and decoupling processes to originate these modules, free from the individuality of the NGP system. We propose that this evolution has been facilitated by a versatile characteristic of the NGP, allowing the association of freely modifiable subordinate common elements to make modules. PMID:23890367

Development of modularity in the neural activity of childrenʼs brains

NASA Astrophysics Data System (ADS)

Chen, Man; Deem, Michael W.

2015-02-01

We study how modularity of the human brain changes as children develop into adults. Theory suggests that modularity can enhance the response function of a networked system subject to changing external stimuli. Thus, greater cognitive performance might be achieved for more modular neural activity, and modularity might likely increase as children develop. The value of modularity calculated from functional magnetic resonance imaging (fMRI) data is observed to increase during childhood development and peak in young adulthood. Head motion is deconvolved from the fMRI data, and it is shown that the dependence of modularity on age is independent of the magnitude of head motion. A model is presented to illustrate how modularity can provide greater cognitive performance at short times, i.e. task switching. A fitness function is extracted from the model. Quasispecies theory is used to predict how the average modularity evolves with age, illustrating the increase of modularity during development from children to adults that arises from selection for rapid cognitive function in young adults. Experiments exploring the effect of modularity on cognitive performance are suggested. Modularity may be a potential biomarker for injury, rehabilitation, or disease.

Dynamics of modularity of neural activity in the brain during development

NASA Astrophysics Data System (ADS)

Deem, Michael; Chen, Man

2014-03-01

Theory suggests that more modular systems can have better response functions at short times. This theory suggests that greater cognitive performance may be achieved for more modular neural activity, and that modularity of neural activity may, therefore, likely increase with development in children. We study the relationship between age and modularity of brain neural activity in developing children. The value of modularity calculated from fMRI data is observed to increase during childhood development and peak in young adulthood. We interpret these results as evidence of selection for plasticity in the cognitive function of the human brain. We present a model to illustrate how modularity can provide greater cognitive performance at short times and enhance fast, low-level, automatic cognitive processes. Conversely, high-level, effortful, conscious cognitive processes may not benefit from modularity. We use quasispecies theory to predict how the average modularity evolves with age, given a fitness function extracted from the model. We suggest further experiments exploring the effect of modularity on cognitive performance and suggest that modularity may be a potential biomarker for injury, rehabilitation, or disease.

Self-assembly and modular functionalization of three-dimensional crystals from oppositely charged proteins

NASA Astrophysics Data System (ADS)

Liljeström, Ville; Mikkilä, Joona; Kostiainen, Mauri A.

2014-07-01

Multicomponent crystals and nanoparticle superlattices are a powerful approach to integrate different materials into ordered nanostructures. Well-developed, especially DNA-based, methods for their preparation exist, yet most techniques concentrate on molecular and synthetic nanoparticle systems in non-biocompatible environment. Here we describe the self-assembly and characterization of binary solids that consist of crystalline arrays of native biomacromolecules. We electrostatically assembled cowpea chlorotic mottle virus particles and avidin proteins into heterogeneous crystals, where the virus particles adopt a non-close-packed body-centred cubic arrangement held together by avidin. Importantly, the whole preparation process takes place at room temperature in a mild aqueous medium allowing the processing of delicate biological building blocks into ordered structures with lattice constants in the nanometre range. Furthermore, the use of avidin-biotin interaction allows highly selective pre- or post-functionalization of the protein crystals in a modular way with different types of functional units, such as fluorescent dyes, enzymes and plasmonic nanoparticles.

Development of a Superconducting Six-Axis Accelerometer

DTIC Science & Technology

1989-07-01

COW tH + R"( rkw rRk . (2.35) Recognizing that the components of the Levi - Civita tensor must remain the same in all Cartesian coordinate systems, this...Dynamics of a Rigid Body in a RuLating Accelerated Reference Frame ........ .................................. 10 2.2.3 Accelerometer Equations of Motion...in the Type-I region where currents are more stable. All the parts fit inside a 10.16 cm titanium cube. Two problems were encountered with this

Comparative Inhalation Screen of Titanium Dioxide and Graphite Dusts

DTIC Science & Technology

1988-11-01

refton.TTNX32pimn is recmmndfrtemnacueorfltiegmbds *OCALLAS:iumNO 302 pigmen id plcto notclo cat lse cotrledb usNAIE oNFLA LS:Aopnnftegasbth TITANOX 3020 pigment...58) described a similar glInds of affected wild rats contained infectious virus by disease of young rats, but inflammation was restricted to the...caused the disease. and Hunt detected acidophilic intra- studied, but virus and/or antibody have been detected in wild nuclear inclusion bodies in

Preparation of titanium diboride powder

DOEpatents

Brynestad, Jorulf; Bamberger, Carlos E.

1985-01-01

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, J.L.

1998-10-13

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics. 6 figs.

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, Jack L.

1998-01-01

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics.

WITHDRAWN: Resorbable versus titanium plates for facial fractures.

PubMed

Dorri, Mojtaba; Oliver, Richard

2018-05-23

Rigid internal fixation of the jaw bones is a routine procedure for the management of facial fractures. Titanium plates and screws are routinely used for this purpose. The limitations of this system has led to the development of plates manufactured from bioresorbable materials which, in some cases, omits the necessity for the second surgery. However, concerns remain about the stability of fixation and the length of time required for their degradation and the possibility of foreign body reactions. To compare the effectiveness of bioresorbable fixation systems with titanium systems for the management of facial fractures. We searched the following databases: The Cochrane Oral Health Group's Trials Register (to 20th August 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 3), MEDLINE (1950 to 20th August 2008), EMBASE (from 1980 to 20th August 2008), http://www.clinicaltrials.gov/ and http://www.controlled-trials.com (to 20th August 2008). Randomised controlled trials comparing resorbable versus titanium fixation systems used for facial fractures. Retrieved studies were independently screened by two review authors. Results were to be expressed as random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals. Heterogeneity was to be investigated including both clinical and methodological factors. The search strategy retrieved 53 potentially eligible studies. None of the retrieved studies met our inclusion criteria and all were excluded from this review. One study is awaiting classification as we failed to obtain the full text copy. Three ongoing trials were retrieved, two of which were stopped before recruiting the planned number of participants. In one study, the excess complications in the resorbable arm was declared as the reason for stopping the trial. This review illustrates that there are no published randomised controlled clinical trials relevant to this review question. There is currently insufficient evidence for the effectiveness of resorbable fixation systems compared with conventional titanium systems for facial fractures. The findings of this review, based on the results of the aborted trials, do not suggest that resorbable plates are as effective as titanium plates. In future, the results of ongoing clinical trials may provide high level reliable evidence for assisting clinicians and patients for decision making. Trialists should design their studies accurately and comprehensively to meet the aims and objectives defined for the study.

Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

PubMed Central

Mellado-Valero, Ana; Igual Muñoz, Anna; Guiñón Pina, Virginia

2018-01-01

The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys. PMID:29361767

The comparison of phosphate-titanate-silicate layers on the titanium and Ti6Al4V alloy base.

PubMed

Rokita, M

2011-08-15

The studied layers were composed of two parts: titanate-silicate underlayer for better adhesion and titanate-phosphate-silicate layers for potential bioparameters. The layers with different amounts of hydroxyapatite were deposited on titanium and Ti6Al4V alloy substrates using dipping sol-gel method and electrophoresis. The selection of sol/suspension composition, deposition time and heat treatment conditions have the decisive influence on the layers parameters. The obtained layers should be very thin and almost amorphous. The specific nature of ceramic layers on the metal substrates excludes the use of some measurements methods or makes it difficult to interpret the measurement results. All the obtained samples were compared using XRD analysis data (GID technique), SEM with EDX measurements and FTIR spectroscopy (transmission and reflection techniques) before and after soaking in simulated body fluid. FTIR spectroscopy with mathematical treatment of the spectra (BIO-RAD Win-IR program, Arithmetic-subtract function) was used to detect the increase or decrease of any phosphate phases during SBF soaking. Based on the FTIR results the processes of hydroxyapatite (HAp) growth or layer dissolution were estimated. The layers deposited on titanium substrate are more crystalline then the ones deposited on Ti6Al4V. During SBF soaking process the growth of small amount of microcrystalline carbonate hydroxyapatite was observed on titanium substrate. The layer on Ti6Al4V base contained amorphous carbonate apatite. During heating treatment above about 870-920 K this apatite transforms into carbonate hydroxyapatite. The Ti6Al4V substrate seems to be more advantageous in context of potentially bioactive materials obtaining. Copyright © 2010 Elsevier B.V. All rights reserved.

Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Chenglong; Xin Yunchang; Tian Xiubo

2007-03-15

Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has threemore » layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO{sub 2} with some Mg(OH){sub 2}. The middle layer that is 50 nm thick comprises predominantly TiO{sub 2} and MgO with minor contributions from MgAl{sub 2}O{sub 4} and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti{sub 3}Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37{+-}1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased {beta}-Mg{sub 12}Al{sub 17} phase.« less

Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva.

PubMed

Mellado-Valero, Ana; Muñoz, Anna Igual; Pina, Virginia Guiñón; Sola-Ruiz, Ma Fernanda

2018-01-22

The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys.

In vitro apatite formation on nano-crystalline titania layer aligned parallel to Ti6Al4V alloy substrates with sub-millimeter gap.

PubMed

Hayakawa, Satoshi; Matsumoto, Yuko; Uetsuki, Keita; Shirosaki, Yuki; Osaka, Akiyoshi

2015-06-01

Pure titanium substrates were chemically oxidized with H2O2 and subsequent thermally oxidized at 400 °C in air to form anatase-type titania layer on their surface. The chemically and thermally oxidized titanium substrate (CHT) was aligned parallel to the counter specimen such as commercially pure titanium (cpTi), titanium alloy (Ti6Al4V) popularly used as implant materials or Al substrate with 0.3-mm gap. Then, they were soaked in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 7 days. XRD and SEM analysis showed that the in vitro apatite-forming ability of the contact surface of the CHT specimen decreased in the order: cpTi > Ti6Al4V > Al. EDX and XPS surface analysis showed that aluminum species were present on the contact surface of the CHT specimen aligned parallel to the counter specimen such as Ti6Al4V and Al. This result indicated that Ti6Al4V or Al specimens released the aluminum species into the SBF under the spatial gap. The released aluminum species might be positively or negatively charged in the SBF and thus can interact with calcium or phosphate species as well as titania layer, causing the suppression of the primary heterogeneous nucleation and growth of apatite on the contact surface of the CHT specimen under the spatial gap. The diffusion and adsorption of aluminum species derived from the half-sized counter specimen under the spatial gap resulted in two dimensionally area-selective deposition of apatite particles on the contact surfaces of the CHT specimen.

Heating of metallic implants and instruments induced by gradient switching in a 1.5-Tesla whole-body unit.

PubMed

Graf, Hansjörg; Steidle, Günter; Schick, Fritz

2007-11-01

To examine gradient switching-induced heating of metallic parts. Copper and titanium frames and sheets ( approximately 50 x 50 mm(2), 1.5 mm thick, frame width = 3 mm) surrounded by air were positioned in the scanner perpendicular to the static field horizontally 20 cm off-center. During the execution of a sequence (three-dimensional [3D] true fast imaging with steady precession [True-FISP], TR = 6.4 msec) exploiting the gradient capabilities (maximum gradient = 40 mT/m, maximum slew rate = 200 T/m/second), heating was measured with an infrared camera. Radio frequency (RF) amplitude was set to zero volts. Heating of a copper frame with a narrowing to 1 mm over 20 mm at one side was examined in air and in addition surrounded by several liters of gelled saline using fiber-optic thermography. Further heating studies were performed using an artificial hip made of titanium, and an aluminum replica of the hip prosthesis with the same geometry. For the copper specimens, considerable heating (>10 degrees C) in air and in gelled saline (>1.2 degrees C) could be observed. Heating of the titanium specimens was markedly less ( approximately 1 degrees C in air). For the titanium artificial hip no heating could be detected, while the rise in temperature for the aluminum replica was approximately 2.2 degrees C. Heating of more than 10 degrees C solely due to gradient switching without any RF irradiation was demonstrated in isolated copper wire frames. Under specific conditions (high gradient duty cycle, metallic loop of sufficient inductance and low resistance, power matching) gradient switching-induced heating of conductive specimens must be considered.

Control of dental-derived induced pluripotent stem cells through modified surfaces for dental application.

PubMed

Choi, Hyunmin; Park, Kyu-Hyung; Lee, Ah-Reum; Mun, Chin Hee; Shin, Yong Dae; Park, Yong-Beom; Park, Young-Bum

2017-07-01

The aim of this study is to investigate the behaviour of iPSc derived from dental stem cells in terms of initial adhesion, differentiation potential on differently surface-treated titanium disc. iPSc derived from human gingival fibroblasts (hGFs) were established using 4-reprogramming factors transduction with Sendai virus. The hGF-iPSc established in this study exhibited the morphology and growth properties similar to human embryonic stem (ES) cells and expressed pluripotency makers. Alkaline Phosphatase (AP) staining, Embryoid Body (EB) formation and in vitro differentiation and karyotyping further confirmed pluripotency of hGF-iPSc. Then, hGF-iPSc were cultured on machined- and Sandblasted and acid etched (SLA)-treated titanium discs with osteogenic induction medium and their morphological as well as quantitative changes according to different surface types were investigated using Alizrin Red S staining, Scanning electron microscopy (SEM), Flow cytometry and RT-PCR. Time-dependent and surface-dependent morphological changes as well as quantitative change in osteogenic differentiation of hGF-iPSc were identified and osteogenic gene expression of hGF-iPSc cultured on SLA-treated titanium disc found to be greater than machined titanium disc, suggesting the fate of hGF-iPSc may be determined by the characteristics of surface to which hGF-iPSc first adhere. iPSc derived from dental stem cell can be one of the most promising and practical cell sources for personalized regenerative dentistry and their morphological change as well as quantitative change in osteogenic differentiation according to different surface types may be further utilized for future clinical application incorporated with dental implant.

Correlation between rate of bony ingrowth to stainless steel, pure titanium, and titanium alloy implants in vivo and formation of hydroxyapatite on their surfaces in vitro.

PubMed

Oron, A; Agar, G; Oron, U; Stein, A

2009-12-15

The rate of bony ingrowth to identical metal implants made of either pure titanium (cpTi), titanium alloy (Ti-6Al-4V), or stainless steel 316L (SS) inserted to the medullar canal of the femur in rats was investigated. The kinetics of spontaneous deposition of hydroxyapatite (HA) globules on the aforementioned metals in vitro during incubation in simulated body fluid (SBF) was also studied. It was found that the rate of increased bonding strength between the cpTi implants and the host bone was the highest, whereas around the SS implants it was the slowest. At 10 days postimplant insertion, the shear strength of the cpTi implants was 2.2- and 4-fold significantly higher than for the Ti-6Al-4V and the SS implants, respectively. Spontaneous formation of the HA globules on the cpTi and Ti-6Al-4V implants that were incubated in the SBF was observed as early as 6 and 10 days after incubation in SBF, respectively, whereas on SS implants, deposition of HA was evident only after 2 weeks of in vitro incubation in SBF. It is concluded that the chemical surface characteristics and the biocompatibility of the implants probably play a key role in the process of bone growth next to them, during the formation of bone in vivo. The rate of bony ingrowth to various metal implants alloys inserted into the medullar canal of rats correlates well with the induction of apatite formation on them during incubation in vitro with SBF.

The comparison of phosphate-titanate-silicate layers on the titanium and Ti6Al4V alloy base

NASA Astrophysics Data System (ADS)

Rokita, M.

2011-08-01

The studied layers were composed of two parts: titanate-silicate underlayer for better adhesion and titanate-phosphate-silicate layers for potential bioparameters. The layers with different amounts of hydroxyapatite were deposited on titanium and Ti6Al4V alloy substrates using dipping sol-gel method and electrophoresis. The selection of sol/suspension composition, deposition time and heat treatment conditions have the decisive influence on the layers parameters. The obtained layers should be very thin and almost amorphous. The specific nature of ceramic layers on the metal substrates excludes the use of some measurements methods or makes it difficult to interpret the measurement results. All the obtained samples were compared using XRD analysis data (GID technique), SEM with EDX measurements and FTIR spectroscopy (transmission and reflection techniques) before and after soaking in simulated body fluid. FTIR spectroscopy with mathematical treatment of the spectra (BIO-RAD Win-IR program, Arithmetic-subtract function) was used to detect the increase or decrease of any phosphate phases during SBF soaking. Based on the FTIR results the processes of hydroxyapatite (HAp) growth or layer dissolution were estimated. The layers deposited on titanium substrate are more crystalline then the ones deposited on Ti6Al4V. During SBF soaking process the growth of small amount of microcrystalline carbonate hydroxyapatite was observed on titanium substrate. The layer on Ti6Al4V base contained amorphous carbonate apatite. During heating treatment above about 870-920 K this apatite transforms into carbonate hydroxyapatite. The Ti6Al4V substrate seems to be more advantageous in context of potentially bioactive materials obtaining.

Influence of Temperature on the Biomechanical Stability of Titanium, PEEK, Poly-L-Lactic Acid, and β-Tricalcium Phosphate Poly-L-Lactic Acid Suture Anchors Tested on Human Humeri In Vitro in a Wet Environment.

PubMed

Güleçyüz, Mehmet F; Mazur, Alexandra; Schröder, Christian; Braun, Christian; Ficklscherer, Andreas; Roßbach, Björn P; Müller, Peter E; Pietschmann, Matthias F

2015-06-01

The purpose of this study was to analyze the biomechanical integrity of suture anchors of different materials (titanium, PEEK [polyether ether ketone], poly-L-lactic acid [PLLA], and β-tricalcium phosphate PLLA) and almost identical design for rotator cuff repair in human humeri positioned in a water bath at room and body temperature undergoing cyclic loading rather than single-pull or static tests. Four different anchor models (n = 6) were tested using healthy human cadaveric humeri in a water bath thermostatically regulated at 20°C and 37°C. A cyclic testing protocol was used. The maximum failure load, the system displacement, and the respective mode of failure were recorded. There were no significant differences regarding the maximum failure load values between the 20°C groups and 37°C groups for the 4 different anchor materials. The displacement values for the 20°C groups and 37°C groups also were not statistically significant. Anchor and suture dislocations were the predominant modes of failure; suture ruptures were observed in few cases. This study shows that there are no significantly relevant differences regarding the maximum failure loads and the displacement values of the tested suture anchor systems in a wet environment at 20°C or 37°C. The temperature differences do not seem to affect the modes of failure either. Titanium, PEEK, PLLA, and β-tricalcium phosphate PLLA suture anchors for rotator cuff repair can be expected-on the basis of this investigation comparing laboratory temperature with body temperature and a wet environment-to perform in vivo similar to in vitro testing. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

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

PubMed

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.

Modular Courses in British Higher Education: A Critical Assessment

ERIC Educational Resources Information Center

Church, Clive

1975-01-01

The trends towards modular course structures is examined. British conceptions of modularization are compared with American interpretations of modular instruction, the former shown to be concerned almost exclusively with content, the latter attempting more radical changes in students' learning behavior. Rationales for British modular schemes are…

Rough titanium alloys regulate osteoblast production of angiogenic factors.

PubMed

Olivares-Navarrete, Rene; Hyzy, Sharon L; Gittens, Rolando A; Schneider, Jennifer M; Haithcock, David A; Ullrich, Peter F; Slosar, Paul J; Schwartz, Zvi; Boyan, Barbara D

2013-11-01

Polyether-ether-ketone (PEEK) and titanium-aluminum-vanadium (titanium alloy) are used frequently in lumbar spine interbody fusion. Osteoblasts cultured on microstructured titanium generate an environment characterized by increased angiogenic factors and factors that inhibit osteoclast activity mediated by integrin α2β1 signaling. It is not known if this is also true of osteoblasts on titanium alloy or PEEK. The purpose of this study was to determine if osteoblasts generate an environment that supports angiogenesis and reduces osteoclastic activity when grown on smooth titanium alloy, rough titanium alloy, or PEEK. This in vitro study compared angiogenic factor production and integrin gene expression of human osteoblast-like MG63 cells cultured on PEEK or titanium-aluminum-vanadium (titanium alloy). MG63 cells were grown on PEEK, smooth titanium alloy, or rough titanium alloy. Osteogenic microenvironment was characterized by secretion of osteoprotegerin and transforming growth factor beta-1 (TGF-β1), which inhibit osteoclast activity and angiogenic factors including vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2), and angiopoietin-1 (ANG-1). Expression of integrins, transmembrane extracellular matrix recognition proteins, was measured by real-time polymerase chain reaction. Culture on titanium alloy stimulated osteoprotegerin, TGF-β1, VEGF-A, FGF-2, and angiopoietin-1 production, and levels were greater on rough titanium alloy than on smooth titanium alloy. All factors measured were significantly lower on PEEK than on smooth or rough titanium alloy. Culture on titanium alloy stimulated expression of messenger RNA for integrins that recognize Type I collagen in comparison with PEEK. Rough titanium alloy stimulated cells to create an osteogenic-angiogenic microenvironment. The osteogenic-angiogenic responses to titanium alloy were greater than PEEK and greater on rough titanium alloy than on smooth titanium alloy. Surface features regulated expression of integrins important in collagen recognition. These factors may increase bone formation, enhance integration, and improve implant stability in interbody spinal fusions. Copyright © 2013 Elsevier Inc. All rights reserved.

Dissociation of modular total hip arthroplasty at the neck-stem interface without dislocation.

PubMed

Kouzelis, A; Georgiou, C S; Megas, P

2012-12-01

Modular femoral and acetabular components are now widely used, but only a few complications related to the modularity itself have been reported. We describe a case of dissociation of the modular total hip arthroplasty (THA) at the femoral neck-stem interface during walking. The possible causes of this dissociation are discussed. Successful treatment was provided with surgical revision and replacement of the modular neck components. Surgeons who use modular components in hip arthroplasties should be aware of possible early complications in which the modularity of the prostheses is the major factor of failure.

Quasispecies theory for evolution of modularity.

PubMed

Park, Jeong-Man; Niestemski, Liang Ren; Deem, Michael W

2015-01-01

Biological systems are modular, and this modularity evolves over time and in different environments. A number of observations have been made of increased modularity in biological systems under increased environmental pressure. We here develop a quasispecies theory for the dynamics of modularity in populations of these systems. We show how the steady-state fitness in a randomly changing environment can be computed. We derive a fluctuation dissipation relation for the rate of change of modularity and use it to derive a relationship between rate of environmental changes and rate of growth of modularity. We also find a principle of least action for the evolved modularity at steady state. Finally, we compare our predictions to simulations of protein evolution and find them to be consistent.

Cell Attachment Following Instrumentation with Titanium and Plastic Instruments, Diode Laser, and Titanium Brush on Titanium, Titanium-Zirconium, and Zirconia Surfaces.

PubMed

Lang, Melissa S; Cerutis, D Roselyn; Miyamoto, Takanari; Nunn, Martha E

2016-01-01

The aim of this study was to evaluate the surface characteristics and gingival fibroblast adhesion of disks composed of implant and abutment materials following brief and repeated instrumentation with instruments commonly used in procedures for implant maintenance, stage-two implant surgery, and periimplantitis treatment. One hundred twenty disks (40 titanium, 40 titaniumzirconium, 40 zirconia) were grouped into treatment categories of instrumentation by plastic curette, titanium curette, diode microlaser, rotary titanium brush, and no treatment. Twenty strokes were applied to half of the disks in the plastic and titanium curette treatment categories, while half of the disks received 100 strokes each to simulate implant maintenance occurring on a repetitive basis. Following analysis of the disks by optical laser profilometry, disks were cultured with human gingival fibroblasts. Cell counts were conducted from scanning electron microscopy (SEM) images. Differences in surface roughness across all instruments tested for zirconia disks were negligible, while both titanium disks and titaniumzirconium disks showed large differences in surface roughness across the spectrum of instruments tested. The rotary titanium brush and the titanium curette yielded the greatest overall mean surface roughness, while the plastic curette yielded the lowest mean surface roughness. The greatest mean cell counts for each disk type were as follows: titanium disks with plastic curettes, titanium-zirconium disks with titanium curettes, and zirconia disks with the diode microlaser. Repeated instrumentation did not result in cumulative changes in surface roughness of implant materials made of titanium, titanium-zirconium, or zirconia. Instrumentation with plastic implant curettes on titanium and zirconia surfaces appeared to be more favorable than titanium implant curettes in terms of gingival fibroblast attachment on these surfaces.

Are clinical findings of systemic titanium dispersion following implantation explained by available in vitro evidence? An evidence-based analysis.

PubMed

Curtin, Justin Paul; Wang, Minji

2017-08-01

Although the presence of titanium wear particles released into tissues is known to induce local inflammation following the therapeutic implantation of titanium devices into humans, the role that titanium ions play in adverse tissue responses has received little attention. Support that ongoing titanium ion release occurs is evidenced by the presence of ionic titanium bound to transferrin in blood, and ongoing excretion in the urine of patients with titanium devices. However, as reports documenting the presence of titanium within tissues do not distinguish between particulate and ionic forms due to technical challenges, the degree to which ionic titanium is released into tissues is unknown. To determine the potential for titanium ion release into tissues, this study evaluates available in vitro evidence relating to the release of ionic titanium under physiological conditions. This is a systematic literature review of studies reporting titanium ion release into solutions from titanium devices under conditions replicating the interstitial pH and constituents. Inclusion and exclusion criteria were defined. Of 452 articles identified, titanium ions were reported in nine media relevant to human biology in seventeen studies. Only one study, using human serum replicated both physiological pH and the concentration of constituents while reporting the presence of titanium ions. While there is insufficient information to explain the factors that contribute to the presence of titanium ions in serum of humans implanted with titanium devices, currently available information suggests that areas of future inquiry include the role of transferrin and organic acids.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siranosian, Antranik Antonio; Schembri, Philip Edward; Miller, Nathan Andrew

The Benchmark Extensible Tractable Testbed Engineering Resource (BETTER) is proposed as a family of modular test bodies that are intended to support engineering capability development by helping to identify weaknesses and needs. Weapon systems, subassemblies, and components are often complex and difficult to test and analyze, resulting in low confidence and high uncertainties in experimental and simulated results. The complexities make it difficult to distinguish between inherent uncertainties and errors due to insufficient capabilities. BETTER test bodies will first use simplified geometries and materials such that testing, data collection, modeling and simulation can be accomplished with high confidence and lowmore » uncertainty. Modifications and combinations of simple and well-characterized BETTER test bodies can then be used to increase complexity in order to reproduce relevant mechanics and identify weaknesses. BETTER can provide both immediate and long-term improvements in testing and simulation capabilities. This document presents the motivation, concept, benefits and examples for BETTER.« less

Self-organized modularization in evolutionary algorithms.

PubMed

Dauscher, Peter; Uthmann, Thomas

2005-01-01

The principle of modularization has proven to be extremely successful in the field of technical applications and particularly for Software Engineering purposes. The question to be answered within the present article is whether mechanisms can also be identified within the framework of Evolutionary Computation that cause a modularization of solutions. We will concentrate on processes, where modularization results only from the typical evolutionary operators, i.e. selection and variation by recombination and mutation (and not, e.g., from special modularization operators). This is what we call Self-Organized Modularization. Based on a combination of two formalizations by Radcliffe and Altenberg, some quantitative measures of modularity are introduced. Particularly, we distinguish Built-in Modularity as an inherent property of a genotype and Effective Modularity, which depends on the rest of the population. These measures can easily be applied to a wide range of present Evolutionary Computation models. It will be shown, both theoretically and by simulation, that under certain conditions, Effective Modularity (as defined within this paper) can be a selection factor. This causes Self-Organized Modularization to take place. The experimental observations emphasize the importance of Effective Modularity in comparison with Built-in Modularity. Although the experimental results have been obtained using a minimalist toy model, they can lead to a number of consequences for existing models as well as for future approaches. Furthermore, the results suggest a complex self-amplification of highly modular equivalence classes in the case of respected relations. Since the well-known Holland schemata are just the equivalence classes of respected relations in most Simple Genetic Algorithms, this observation emphasizes the role of schemata as Building Blocks (in comparison with arbitrary subsets of the search space).

[Modular enteral nutrition in pediatrics].

PubMed

Murillo Sanchís, S; Prenafeta Ferré, M T; Sempere Luque, M D

1991-01-01

Modular Enteral Nutrition may be a substitute for Parenteral Nutrition in children with different pathologies. Study of 4 children with different pathologies selected from a group of 40 admitted to the Maternal-Childrens Hospital "Valle de Hebrón" in Barcelona, who received modular enteral nutrition. They were monitored on a daily basis by the Dietician Service. Modular enteral nutrition consists of modules of proteins, peptides, lipids, glucids and mineral salts-vitamins. 1.--Craneo-encephalic traumatisms with loss of consciousness, Feeding with a combination of parenteral nutrition and modular enteral nutrition for 7 days. In view of the tolerance and good results of the modular enteral nutrition, the parenteral nutrition was suspended and modular enteral nutrition alone used up to a total of 43 days. 2.--55% burns with 36 days of hyperproteic modular enteral nutrition together with normal feeding. A more rapid recovery was achieved with an increase in total proteins and albumin. 3.--Persistent diarrhoea with 31 days of modular enteral nutrition, 5 days on parenteral nutrition alone and 8 days on combined parenteral nutrition and modular enteral nutrition. In view of the tolerance and good results of the modular enteral nutrition, the parenteral nutrition was suspended. 4.--Mucoviscidosis with a total of 19 days on modular enteral nutrition, 12 of which were exclusively on modular enteral nutrition and 7 as a night supplement to normal feeding. We administered proteic intakes of up to 20% of the total calorific intake and in concentrations of up to 1.2 calories/ml of the final preparation, always with a good tolerance. Modular enteral nutrition can and should be used as a substitute for parenteral nutrition in children with different pathologies, thus preventing the complications inherent in parenteral nutrition.

Convergent evolution of modularity in metabolic networks through different community structures.

PubMed

Zhou, Wanding; Nakhleh, Luay

2012-09-14

It has been reported that the modularity of metabolic networks of bacteria is closely related to the variability of their living habitats. However, given the dependency of the modularity score on the community structure, it remains unknown whether organisms achieve certain modularity via similar or different community structures. In this work, we studied the relationship between similarities in modularity scores and similarities in community structures of the metabolic networks of 1021 species. Both similarities are then compared against the genetic distances. We revisited the association between modularity and variability of the microbial living environments and extended the analysis to other aspects of their life style such as temperature and oxygen requirements. We also tested both topological and biological intuition of the community structures identified and investigated the extent of their conservation with respect to the taxonomy. We find that similar modularities are realized by different community structures. We find that such convergent evolution of modularity is closely associated with the number of (distinct) enzymes in the organism's metabolome, a consequence of different life styles of the species. We find that the order of modularity is the same as the order of the number of the enzymes under the classification based on the temperature preference but not on the oxygen requirement. Besides, inspection of modularity-based communities reveals that these communities are graph-theoretically meaningful yet not reflective of specific biological functions. From an evolutionary perspective, we find that the community structures are conserved only at the level of kingdoms. Our results call for more investigation into the interplay between evolution and modularity: how evolution shapes modularity, and how modularity affects evolution (mainly in terms of fitness and evolvability). Further, our results call for exploring new measures of modularity and network communities that better correspond to functional categorizations.

Multispectral optical tweezers for molecular diagnostics of single biological cells

NASA Astrophysics Data System (ADS)

Butler, Corey; Fardad, Shima; Sincore, Alex; Vangheluwe, Marie; Baudelet, Matthieu; Richardson, Martin

2012-03-01

Optical trapping of single biological cells has become an established technique for controlling and studying fundamental behavior of single cells with their environment without having "many-body" interference. The development of such an instrument for optical diagnostics (including Raman and fluorescence for molecular diagnostics) via laser spectroscopy with either the "trapping" beam or secondary beams is still in progress. This paper shows the development of modular multi-spectral imaging optical tweezers combining Raman and Fluorescence diagnostics of biological cells.

Method of making a unitized electrode assembly

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Solomon, Frank; Niksa, Andrew J.; Schue, Thomas J.; Genodman, Yury; Turk, Thomas R.; Hagel, Daniel P.

1988-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Method of making a unitized electrode assembly

DOEpatents

Niksa, M.J.; Pohto, G.R.; Lakatos, L.K.; Wheeler, D.J.; Solomon, F.; Niksa, A.J.; Schue, T.J.; Genodman, Y.; Turk, T.R.; Hagel, D.P.

1988-12-06

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom. 6 figs.

Titanium

USGS Publications Warehouse

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 mining are minimal; however, the processes required to extract titanium from titanium feedstock can produce industrial waste.

Implicit Contractive Mappings in Modular Metric and Fuzzy Metric Spaces

PubMed Central

Hussain, N.; Salimi, P.

2014-01-01

The notion of modular metric spaces being a natural generalization of classical modulars over linear spaces like Lebesgue, Orlicz, Musielak-Orlicz, Lorentz, Orlicz-Lorentz, and Calderon-Lozanovskii spaces was recently introduced. In this paper we investigate the existence of fixed points of generalized α-admissible modular contractive mappings in modular metric spaces. As applications, we derive some new fixed point theorems in partially ordered modular metric spaces, Suzuki type fixed point theorems in modular metric spaces and new fixed point theorems for integral contractions. In last section, we develop an important relation between fuzzy metric and modular metric and deduce certain new fixed point results in triangular fuzzy metric spaces. Moreover, some examples are provided here to illustrate the usability of the obtained results. PMID:25003157

Grafting strategy to develop single site titanium on an amorphous silica surface.

PubMed

Capel-Sanchez, M C; Blanco-Brieva, G; Campos-Martin, J M; de Frutos, M P; Wen, W; Rodriguez, J A; Fierro, J L G

2009-06-16

Titanium/silica systems were prepared by grafting a titanium alkoxide (titanium isopropoxide and titanium (triethanolaminate) isopropoxide) precursor onto amorphous silica. The grafting process, which consisted of the hydrolysis of the Ti precursor by the hydroxyl groups on the silica surface, yielded samples containing Ti-loadings of 1-1.6 wt %. The as synthesized and calcined TiO(2)-SiO(2) samples were characterized by UV-vis, FTIR, XPS, and XANES spectroscopic techniques. These systems were tested in the liquid-phase epoxidation of oct-1-ene with hydrogen peroxide reaction. Spectroscopic data indicated that titanium anchoring takes place by reaction between the alkoxide precursor and surface OH groups of the silica substrate. The nature of surface titanium species generated by chemical grafting depends largely on the titanium precursor employed. Thus, the titanium isopropoxide precursor yields tetrahedrally coordinated polymeric titanium species, which give rise to a low-efficiency catalyst. However, if an atrane precursor (titanium (triethanolaminate) isopropoxide) is employed, isolated titanium species are obtained. The fact that these species remain isolated even after calcination is due to the protective effect of the triethanolaminate ligand that avoids titanium polymerization. These differences in the titanium environment have a pivotal role in the performance of these systems in the epoxidation of alkenes with hydrogen peroxide.

Grafting Strategy to Develop Single Site Titanium on an Amorphous Silica Surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capel-Sanchez, M.; Blanco-Brieva, G; Campos-Martin, J

2009-01-01

Titanium/silica systems were prepared by grafting a titanium alkoxide (titanium isopropoxide and titanium (triethanolaminate) isopropoxide) precursor onto amorphous silica. The grafting process, which consisted of the hydrolysis of the Ti precursor by the hydroxyl groups on the silica surface, yielded samples containing Ti-loadings of 1-1.6 wt %. The as synthesized and calcined TiO2-SiO2 samples were characterized by UV-vis, FTIR, XPS, and XANES spectroscopic techniques. These systems were tested in the liquid-phase epoxidation of oct-1-ene with hydrogen peroxide reaction. Spectroscopic data indicated that titanium anchoring takes place by reaction between the alkoxide precursor and surface OH groups of the silica substrate.more » The nature of surface titanium species generated by chemical grafting depends largely on the titanium precursor employed. Thus, the titanium isopropoxide precursor yields tetrahedrally coordinated polymeric titanium species, which give rise to a low-efficiency catalyst. However, if an atrane precursor (titanium (triethanolaminate) isopropoxide) is employed, isolated titanium species are obtained. The fact that these species remain isolated even after calcination is due to the protective effect of the triethanolaminate ligand that avoids titanium polymerization. These differences in the titanium environment have a pivotal role in the performance of these systems in the epoxidation of alkenes with hydrogen peroxide.« less

Modular Power Standard for Space Explorations Missions

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.; Gardner, Brent G.

2016-01-01

Future human space exploration will most likely be composed of assemblies of multiple modular spacecraft elements with interconnected electrical power systems. An electrical system composed of a standardized set modular building blocks provides significant development, integration, and operational cost advantages. The modular approach can also provide the flexibility to configure power systems to meet the mission needs. A primary goal of the Advanced Exploration Systems (AES) Modular Power System (AMPS) project is to establish a Modular Power Standard that is needed to realize these benefits. This paper is intended to give the space exploration community a "first look" at the evolving Modular Power Standard and invite their comments and technical contributions.

Detection of orthopaedic implants by airport metal detectors.

PubMed

Obremskey, William T; Austin, Tom; Crosby, Colin; Driver, Robin; Kurtz, Will; Shuler, Franklin; Kregor, Philip

2007-02-01

To report the effect of patient's body mass index (BMI), implant type, size, location, number, and material on detection by certified Transportation Security Administration (TSA) and Federal Aviation Administration (FAA) airport metal detectors set to today's standard sensitivity. Retrospective clinical study. Level 1 university trauma center. Ninety-six regularly scheduled trauma clinic patients with a wide variety of orthopaedic implants were enrolled in the study from August 2004 through December 2004. Patients walked through an airport arch metal detector and were also wanded with a handheld metal detector. Detection of implants by arch detector or wand was recorded. We also gathered information regarding BMI, location of implants, type, metal composition, and size. All unilateral prostheses (8/8) and bilateral prostheses (1/1) were detected. Subjects with 4 or fewer screws and no other implants were never detected by the arch metal detector (0/7). For the remaining 78 subjects, the 2 best predictors of detection by the arch were having plates of length >10 holes and having titanium nails (P < 0.001 for each predictor, Wald's test for effects in a logistic model). Prostheses, plates of length >10 holes, and titanium nails were the best predictors of detection by the arch. These 3 factors accounted for 42 of the 43 detections by the arch. Body mass index was not shown to affect detectability of orthopaedic implants.

Synthesis of polycaprolactone-titanium oxide multilayer films by nanosecond laser pulses and electrospinning technique for better implant fabrication

NASA Astrophysics Data System (ADS)

Naghshine, Babak B.; Cosman, James A.; Kiani, Amirkianoosh

2016-08-01

In this study, a combination of electrospinning and laser texturing is introduced as a novel method for increasing the biocompatibility of metal implants. Besides having a rough laser treated surface, the implant benefits from the high porosity and better wettability of an electrospun fibrous structure, which is a more favorable environment for cell proliferation. Titanium samples were patterned using a nanosecond laser beam and were placed as collectors in an electrospinning machine. They were then soaked in simulated body fluid for four weeks. Energy Dispersive X-ray and X-Ray Diffraction results indicate significantly more hydroxyapatite formation on laser treated samples with nanoscale fibers deposited on their surface. This shows that having a laser treated surface underneath the fibrous layer can improve short-term biocompatibility even before degradation of fibers. The thermal conductivity of the electrospun layer, measured using a Hot Disk Transient Plane Source instrument and computer code, was shown to be considerably lower than that of titanium and very close to bone. The presence of this layer can therefore be beneficial in making the implant more compatible to a biological medium. In case of dental implants, it was shown that this layer can act as a thermal barrier while a hot beverage is consumed and it can decrease the temperature rise by about 60%, which avoids any possible damage to newly formed cells during the healing period.

A study of the uptake and biodistribution of nano-titanium dioxide using in vitro and in vivo models of oral intake

NASA Astrophysics Data System (ADS)

MacNicoll, Alan; Kelly, Mick; Aksoy, Hatice; Kramer, Evelien; Bouwmeester, Hans; Chaudhry, Qasim

2015-02-01

Certain food additives may contain a sizeable fraction of particles in the nanoscale. However, little is known about the fate, behaviour and toxicological effects of orally-ingested nanoparticles. This study investigated the uptake and biodistribution of nano- and larger-sized titanium dioxide (TiO2) using an in vitro model of gut epithelium and in vivo in rat. The results of the in vivo study showed that oral administration of 5 mg/kg body weight of TiO2 nano- or larger particles did not lead to any significant translocation of TiO2 (measured as titanium) either to blood, urine or to various organs in rat at any of the time intervals studied over a 96 h post-administration period. Different methods used for dispersing particles did not affect the uptake, and orally administered TiO2 was found excreted in the faeces over a period of time. The in vitro study provided further evidence for the lack of translocation of TiO2 across the gut epithelium model. The overall evidence from both in vivo and in vitro studies did not support that oral ingestion of nano- or larger particles of TiO2 via food would result in any significant internal exposure of the consumer to the nanoparticles. The dietary TiO2 nanoparticles are likely to be excreted in the faeces.

Micro- to Macroroughness of Additively Manufactured Titanium Implants in Terms of Coagulation and Contact Activation.

PubMed

Klingvall Ek, Rebecca; Hong, Jaan; Thor, Andreas; Bäckström, Mikael; Rännar, Lars-Erik

This study aimed to evaluate how as-built electron beam melting (EBM) surface properties affect the onset of blood coagulation. The properties of EBM-manufactured implant surfaces for placement have, until now, remained largely unexplored in literature. Implants with conventional designs and custom-made implants have been manufactured using EBM technology and later placed into the human body. Many of the conventional implants used today, such as dental implants, display modified surfaces to optimize bone ingrowth, whereas custom-made implants, by and large, have machined surfaces. However, titanium in itself demonstrates good material properties for the purpose of bone ingrowth. Specimens manufactured using EBM were selected according to their surface roughness and process parameters. EBM-produced specimens, conventional machined titanium surfaces, as well as PVC surfaces for control were evaluated using the slide chamber model. A significant increase in activation was found, in all factors evaluated, between the machined samples and EBM-manufactured samples. The results show that EBM-manufactured implants with as-built surfaces augment the thrombogenic properties. EBM that uses Ti6Al4V powder appears to be a good manufacturing solution for load-bearing implants with bone anchorage. The as-built surfaces can be used "as is" for direct bone contact, although any surface treatment available for conventional implants can be performed on EBM-manufactured implants with a conventional design.

Sol gel derived hydroxyapatite coatings on titanium and its alloy Ti6Al4V

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzebski, W.; Długoń, E.; Lejda, W.; Trybalska, B.; Stoch, G. J.; Adamczyk, A.

2005-06-01

Titanium has been used for many medical and dental applications; however, its joining to a living bone is not satisfactorily good or the implant integration with bone tissue takes several months.The aim of this work is to produce hydroxyapatite (HAP) coatings on titanium and its alloy for facilitating and shortening the processes towards osseointegration. HAP coatings were obtained by sol-gel method with sol solutions prepared from calcium nitrate tetrahydrate and triammonium phosphate trihydrate as the calcium and phosphorous sources. Two types of gelatine were added to the sol: agar-agar or animals gelatine. Both were found to enhance the formation and stability of amorphous HAP using soluble salts as the sources of calcium and phosphate. HAP coatings were deposited from HAP-GEL sol using dip-withdrawal technique, then the plates were dried and annealed at temperatures 460-750 °C. FTIR spectroscopy and XRD analysis were used to study the phase composition of phosphate coatings. Morphology and chemical analysis of HAP layers was performed using a scanning electron microscope equipped with an energy dispersive X-ray analyser (SEM+EDX). The biological activity of sol-gel phosphate coatings was observed during thermostatic held in simulated body fluid (SBF). It was found that chemical composition and structure of HAP coatings depends on pH and final thermal treatment of the layer.

Novel Bioactive Antimicrobial Lignin Containing Coatings on Titanium Obtained by Electrophoretic Deposition

PubMed Central

Erakovic, Sanja; Jankovic, Ana; Tsui, Gary C. P.; Tang, Chak-Yin; Miskovic-Stankovic, Vesna; Stevanovic, Tatjana

2014-01-01

Hydroxyapatite (HAP) is the most suitable biocompatible material for bone implant coatings; its brittleness, however, is a major obstacle, and the reason why research focuses on creating composites with biopolymers. Organosolv lignin (Lig) is used for the production of composite coatings, and these composites were examined in this study. Titanium substrate is a key biomedical material due to its well-known properties, but infections of the implantation site still impose a serious threat. One approach to prevent infection is to improve antimicrobial properties of the coating material. Silver doped hydroxyapatite (Ag/HAP) and HAP coatings on titanium were obtained by an electrophoretic deposition method in order to control deposited coating mass and morphology by varying applied voltage and deposition time. The effect of lignin on microstructure, morphology and thermal behavior of biocomposite coatings was investigated. The results showed that higher lignin concentrations protect the HAP lattice during sintering, improving coating stability. The corrosion stability was evaluated in simulated body fluid (SBF) at 37 °C. Newly formed plate-shaped carbonate-HAP was detected, indicating enhanced bioactive performance. The antimicrobial efficiency of Ag/HAP/Lig was confirmed by its higher reduction of bacteria Staphylococcus aureus TL (S. aureus TL) than of HAP/Lig coating. Cytotoxicity assay revealed that both coatings can be classified as non-toxic against healthy immunocompetent peripheral blood mononuclear cells (PBMC). PMID:25019343

Novel bioactive antimicrobial lignin containing coatings on titanium obtained by electrophoretic deposition.

PubMed

Erakovic, Sanja; Jankovic, Ana; Tsui, Gary C P; Tang, Chak-Yin; Miskovic-Stankovic, Vesna; Stevanovic, Tatjana

2014-07-11

Hydroxyapatite (HAP) is the most suitable biocompatible material for bone implant coatings; its brittleness, however, is a major obstacle, and the reason why research focuses on creating composites with biopolymers. Organosolv lignin (Lig) is used for the production of composite coatings, and these composites were examined in this study. Titanium substrate is a key biomedical material due to its well-known properties, but infections of the implantation site still impose a serious threat. One approach to prevent infection is to improve antimicrobial properties of the coating material. Silver doped hydroxyapatite (Ag/HAP) and HAP coatings on titanium were obtained by an electrophoretic deposition method in order to control deposited coating mass and morphology by varying applied voltage and deposition time. The effect of lignin on microstructure, morphology and thermal behavior of biocomposite coatings was investigated. The results showed that higher lignin concentrations protect the HAP lattice during sintering, improving coating stability. The corrosion stability was evaluated in simulated body fluid (SBF) at 37 °C. Newly formed plate-shaped carbonate-HAP was detected, indicating enhanced bioactive performance. The antimicrobial efficiency of Ag/HAP/Lig was confirmed by its higher reduction of bacteria Staphylococcus aureus TL (S. aureus TL) than of HAP/Lig coating. Cytotoxicity assay revealed that both coatings can be classified as non-toxic against healthy immunocompetent peripheral blood mononuclear cells (PBMC).

Research on tool wearing on milling of TC21 titanium alloy

NASA Astrophysics Data System (ADS)

Guilin, Liu

2017-06-01

Titanium alloys are used in aircraft widely, but the efficiency is a problem for machining titanium alloy. In this paper, the cutting experiment of TC21 titanium alloy was studied. Cutting parameters and test methods for TC21 titanium alloy were designed. The wear behavior of TC21 titanium alloy was studied based on analysis of orthogonal test results. It provides a group of cutting parameters for TC21 titanium alloy processing.

[Cr-Ti-Al-N complex coating on titanium to strengthen Ti/porcelain bonding].

PubMed

Zhang, Hui; Guo, Tian-wen; Li, Jun-ming; Pan, Jing-guang; Dang, Yong-gang; Tong, Yu

2006-02-01

To study the feasibility of magnetron sputtering Cr-Ti-Al-N complex coating as an interlayer on titanium to enhance the titanium-ceramic binding strength. With a three-point bending test according to ISO 9693, the binding strength of Duceratin (Degussa) to titanium substrate prepared with 4 different surface treatments (polishing, polishing and megnetron sputtering Cr, Ti, Al, and N complex coating, sandblasting, sandblasting and coating) was evaluated. Ti/porcelain interface and fractured Ti surface were examined using scanning electron microscopy with energy-dispersive spectrometry (EDS). The binding strength of polished and coated titanium/Duceratin was significantly higher than polished titanium group (P<0.05). The binding strength of sandblasted and coated titanium/Duceratin did not differ significantly from that of sandblasted titanium group (P>0.05), and the strength in the two sandblasted titanium groups was significantly higher than that in polished and coated titanium group (P<0.05). Megnetron sputtering Cr-Ti-Al-N complex on polished titanium can increase the titanium/porcelain binding strength. Megnetron sputtering coating is a promising Ti/porcelain interlayer.

Distortion of CAD-CAM-fabricated implant-fixed titanium and zirconia complete dental prosthesis frameworks.

PubMed

Al-Meraikhi, Hadi; Yilmaz, Burak; McGlumphy, Edwin; Brantley, William A; Johnston, William M

2018-01-01

Computer-aided design and computer-aided manufacturing (CAD-CAM)-fabricated titanium and zirconia implant-supported fixed dental prostheses have become increasingly popular for restoring patients with complete edentulism. However, the distortion level of these frameworks is not well known. The purpose of this in vitro study was to compare the 3-dimensional (3D) distortion of CAD-CAM zirconia and titanium implant-fixed screw-retained complete dental prostheses. A master edentulous model with 4 implants at the positions of the maxillary first molars and canines was used. Multiunit abutments (Nobel Biocare) secured to the model were digitally scanned using scan bodies and a laboratory scanner (S600 ARTI; Zirkonzahn). Titanium (n=5) and zirconia (n=5) frameworks were milled using a CAD-CAM system (Zirkonzahn M1; Zirkonzahn). All frameworks were scanned using an industrial computed tomography (CT) scanner (Nikon/X-Tek XT H 225kV MCT Micro-Focus). The direct CT scans were reconstructed to generate standard tessellation language (STL) files. To calculate the 3D distortion of the frameworks, STL files of the CT scans were aligned to the CAD model using a sum of the least squares best-fit algorithm. Surface comparison points were placed on the CAD model on the midfacial aspect of all teeth. The 3D distortion of each direct scan to the CAD model was calculated. In addition, color maps of the scan-to-CAD comparison were constructed using a ±0.500 mm color scale range. Both materials exhibited distortion; however, no significant difference was found in the amount of distortion from the CAD model between the materials (P=.747). Absolute values of deviations from the CAD model were evident in the x and y plane and less so in the z direction. Zirconia and titanium frameworks showed similar 3D distortion compared with the CAD model for the tested CAD-CAM and implant systems. The distortion was more pronounced in the horizontal and sagittal plane than in the vertical plane. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Configurable double-sided modular jet impingement assemblies for electronics cooling

DOEpatents

Zhou, Feng; Dede, Ercan Mehmet

2018-05-22

A modular jet impingement assembly includes an inlet tube fluidly coupled to a fluid inlet, an outlet tube fluidly coupled to a fluid outlet, and a modular manifold having a first distribution recess extending into a first side of the modular manifold, a second distribution recess extending into a second side of the modular manifold, a plurality of inlet connection tubes positioned at an inlet end of the modular manifold, and a plurality of outlet connection tubes positioned at an outlet end of the modular manifold. A first manifold insert is removably positioned within the first distribution recess, a second manifold insert is removably positioned within the second distribution recess, and a first and second heat transfer plate each removably coupled to the modular manifold. The first and second heat transfer plates each comprise an impingement surface.

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

NASA Astrophysics Data System (ADS)

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.

Effects of N2/O2 flow rate on the surface properties and biocompatibility of nano-structured TiOxNy thin films prepared by high vacuum magnetron sputtering

NASA Astrophysics Data System (ADS)

Saleem, Sehrish; Ahmad, R.; Ikhlaq, Uzma; Ayub, R.; Wei, Hong Jin; Rui Zhen, Xu; Peng, Hui Li; Abbas, Khizra; Chu, Paul K.

2015-07-01

NiTi shape memory alloys (SMA) have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some applications. In this work, titanium oxynitride films were deposited on NiTi samples by high vacuum magnetron sputtering for various nitrogen and oxygen gas flow rates. The x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) results reveal the presence of different phases in the titanium oxynitride thin films. Energy dispersive spectroscopy (EDS) elemental mapping of samples after immersion in simulated body fluids (SBF) shows that Ni is depleted from the surface and cell cultures corroborate the enhanced biocompatibility in vitro. Project supported by the Higher Education Commission, Hong Kong Research Grants Council (RGC) General Research Funds (GRF), China (Grant No. 112212) and the City University of Hong Kong Applied Research Grant (ARG), China (Grant No. 9667066).

[Apatite-forming ability of pure titanium implant after micro-arc oxidation treatment].

PubMed

Tian, Zhihui; Zhang, Yu; Wang, Lichao; Nan, Kaihui

2013-10-01

To investigate the apatite forming ability of pure titanium implant after micro-arc oxidation treatment in simulated body fluid (SBF) and obtain implants with calcium phosphate (Ca-P) layers. The implants were immersed in (SBF) after micro-arc oxidation treatment for different time lengths, and their apatite forming ability and the morphology and constituents of the Ca-P layers formed on the sample surface were analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive electron probe. After immersion in SBF, large quantities of Ca-P layers were induced on the surface of the samples. The Ca-P layers were composed of octacalcium phosphate and carbonated hydroxyapatite, and the crystals showed a plate-like morphology with an oriented growth. The implants with micro-arc oxidation treatment show good apatite forming ability on the surface with rich calcium and phosphorus elements. The formed layers are composed of bone-like apatite including octacalcium phosphate and carbonated hydroxyapatite.

A bioactive coating of a silica xerogel/chitosan hybrid on titanium by a room temperature sol-gel process.

PubMed

Jun, Shin-Hee; Lee, Eun-Jung; Yook, Se-Won; Kim, Hyoun-Ee; Kim, Hae-Won; Koh, Young-Hag

2010-01-01

A bioactive coating consisting of a silica xerogel/chitosan hybrid was applied to Ti at room temperature as a novel surface treatment for metallic implants. A crack-free thin layer (<2 microm) was coated on Ti with a chitosan content of >30 vol.% through a sol-gel process. The coating layer became more hydrophilic with increasing silica xerogel content, as assessed by contact angle measurement. The hybrid coatings afforded excellent bone bioactivity by inducing the rapid precipitation of apatite on their surface when immersed in a simulated body fluid (SBF). Osteoblastic cells cultured on the hybrid coatings were more viable than those on a pure chitosan coating. Furthermore, the alkaline phosphate activity of the cells was significantly higher on the hybrid coatings than on a pure chitosan coating, with the highest level being achieved on the hybrid coating containing 30% chitosan. These results indicate that silica xerogel/chitosan hybrids are potentially useful as room temperature bioactive coating materials on titanium-based medical implants.

Evaluation of Tribocharged Electrostatic Beneficiation of Lunar Simulant in Lunar Gravity

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline W.; Captain, Jim G.; Weis, Kyle; Santiago-Maldonado, Edgardo; Trigwell, Steve

2011-01-01

The lunar regolith has high concentrations of aluminum, silicon, calcium, iron, sodium, and titanium oxides. Liberation of these metals would provide necessary materials for structural and building material fabrication, spare part, machine and tool production, and construction and site preparation in-situ on the moon or other extraterrestrial body (Rao et al 1979). Ilmenite (FeTi03) is a mineral of interest on the moon as a source of iron, titanium, and oxygen (Cameron 1992, Zhao and Shadman 1993) and therefore enrichment of this mineral in the feedstock before processing would be a considerable advantage in reducing energy requirements to process regolith. Not only for construction materials, but shipping oxygen and water from earth is weight prohibitive, and so investigations into the potential production of oxygen from the oxides of lunar regolith are a major research initiative by NASA (Sibille et al. 2009, Moscatello et al. 2009). In this paper, the results of electrostatic beneficiation of two sets of lunar simulants on two different reduced gravity flight series are presented.

Bioactivity evaluation of titanium/hydroxyapatite composite coating on stainless steel prepared by thermal spraying

NASA Astrophysics Data System (ADS)

Azhar, Nurul Humaira; Talari, Mahesh Kumar; Koong, Chue Keen

2015-08-01

In this study, titanium powder mixed with different wt % of HA was coated on stainless steel (SS) substrate using high velocity oxy-fuel (HVOF) technique to produce composite coating for biomedical applications. As the addition of HA is expected to influence the bioactivity of the coatings, these coatings were investigated for bioactivity by immersing the samples in a simulated body fluid (SBF) solution for 14 days. The apatite growth rate was evaluated by measuring Ca and P concentration in the SBF using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The concentrations of Ca and P have decreased over time in the SBF, suggesting a bone like apatite precipitation on the sample surface. It was observed that pH value increased with the increase of immersion time during initial three days and a subsequent drop after 7 days. Microstructure analysis done using FESEM technique showed nucleation and growth of bone-like apatite on the surface of the coating.

Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants

PubMed Central

Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

2014-01-01

Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier–Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. PMID:24664988

Effects of Ti and TiC ceramic powder on laser-cladded Ti-6Al-4V in situ intermetallic composite

NASA Astrophysics Data System (ADS)

Ochonogor, O. F.; Meacock, C.; Abdulwahab, M.; Pityana, S.; Popoola, A. P. I.

2012-12-01

Titanium metal matrix composite (MMCs) was developed on titanium alloy (Ti-6Al-4V) substrate with the aim of improving the hardness and wear properties by laser cladding technique using a Rofin Sinar 4 kW Nd: YAG laser. Wear investigations were carried out with the aid of three body abrasion tester. The resultant microstructure show homogeneous distribution of TiC particles free from cracks and pores. Multiple track deposited systems with 50% overlap revealed micro-hardness increase from 357.3 HV0.1for the substrate reaching a peak as high as 922.2 HV0.1 for 60%Ti + 40%TiC and the least 665.3 HV0.1 for 80%Ti + 20%TiC MMCs. The wear resistance of the materials improved significantly, indicating a fifteen-fold wear rate reduction due to the proper distribution of ceramic particles thereby forming interstitial carbides as revealed by the X-ray diffraction spectrum.

Effect of sandblasting intensity on microstructures and properties of pure titanium micro-arc oxidation coatings in an optimized composite technique

NASA Astrophysics Data System (ADS)

Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; He, Kun; Yuan, Y. F.; Ma, Xiao-Ni; Li, Ying

2014-02-01

Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.

Photo-induced toxicity of titanium dioxide nanoparticles to Daphnia magna under natural sunlight.

PubMed

Mansfield, C M; Alloy, M M; Hamilton, J; Verbeck, G F; Newton, K; Klaine, S J; Roberts, A P

2015-02-01

Titanium dioxide nanoparticles (TiO2 NP) are one of the most abundantly utilized nanoparticles in the world. Studies have demonstrated the ability of the anatase crystal of TiO2 NP to produce reactive oxygen species (ROS) in the presence of ultraviolet radiation (UVR), a co-exposure likely to occur in aquatic ecosystems. The goal of this study was to examine the photo-induced toxicity of anatase TiO2 NP under natural sunlight to Daphnia magna. D. magna were exposed to a range of UVR intensities and anatase TiO2 concentrations in an outdoor exposure system using the sun as the source of UVR. Different UVR intensities were achieved using UVR opaque and transparent plastics. AnataseTiO2-NP demonstrated the reciprocal relationship seen in other phototoxic compounds such as polycyclic aromatic hydrocarbons (PAHs) at higher UVR treatments. The calculated 8h LC50 of anatase TiO2 NP was 139 ppb under full intensity ambient natural sunlight, 778 ppb under 50% natural sunlight, and >500 ppm under 10% natural sunlight. Mortality was also compared between animals allowed to accumulate a body burden of anatase TiO2 for 1h and organisms whose first exposure to anatase TiO2 aqueous suspensions occurred under UVR. A significantly greater toxic effect was observed in aqueous, low body burden suspensions than that of TiO2 1h body burdens, which is dissimilar from the model presented in PAHs. Anatase TiO2 presents a unique photo-induced toxic model that is different than that of established phototoxic compounds. Copyright © 2014 Elsevier Ltd. All rights reserved.

Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

NASA Astrophysics Data System (ADS)

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-sized titanium aluminide powders were rapidly consolidated to form near-net shape titanium aluminide parts in form of small discs and tiles. The rapidly consolidated titanium aluminide parts were found to be fully dense. The microstructure morphology was found to vary with consolidation conditions. The mechanical properties were found to be significantly dependent on microstructure morphology and grain size. Due to rapid consolidation, grain growth during consolidation was limited, which in turn led to enhanced mechanical properties. The high temperature mechanical properties for the consolidated titanium aluminide samples were characterized and were found to retain good mechanical performance up to 700°C. Micron-sized titanium aluminide powders with slightly less Aluminum and small Nb, and Cr additions were rapidly consolidated into near-net shape parts. The consolidated parts were found to exhibit enhanced mechanical performance in terms of ductility and yield strength. The negative effect of Oxygen on the flexural strength at high temperatures was found to be reduced with the addition of Nb. In an effort to further reduce the grain size of the consolidated titanium aluminide samples, the as-received titanium aluminide powders were milled in an attrition mill. The average powder particle size of the powders was reduced by 60% after milling. The milled powders were then rapidly consolidated. The grain size of the consolidated parts was found to be in the sub-micrometer range. The mechanical properties were found to be significantly enhanced due to reduction of grain size in the sub-micrometer range. In order to develop a metal matrix composite based on titanium aluminide matrix reinforced with titanium boride, an experiment to study the effect of rapid consolidation on titanium diboride powders was conducted. Micron-sized titanium diboride powders were consolidated and were found to be 93% dense and exhibited minimal grain growth. The low density of the consolidated part was attributed to low consolidation temperature. Titanium aluminide and titanium diboride powders were blended together in an attrition mill and rapidly consolidated. A metal matrix composite with titanium aluminide matrix reinforced with titanium monoboride plates was formed. The titanium diboride in the powder form was found to be transformed to titanium monoboroide plates during consolidation due to the thermodynamic equilibrium between titanium and titanium monoboride. The metal matrix composite was found to be 90% dense. The low density was due to particle size mismatch between the matrix and reinforcement powders and low consolidation temperature. An increase in the volume of titanium monoboride plates in the metal matrix composite was accompanied by an increase in the elastic modulus of the metal matrix composite.

Preparation of metal diboride powders

DOEpatents

Brynestad, J.; Bamberger, C.E.

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group of consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Cytotoxicity of titanium and titanium alloying elements.

PubMed

Li, Y; Wong, C; Xiong, J; Hodgson, P; Wen, C

2010-05-01

It is commonly accepted that titanium and the titanium alloying elements of tantalum, niobium, zirconium, molybdenum, tin, and silicon are biocompatible. However, our research in the development of new titanium alloys for biomedical applications indicated that some titanium alloys containing molybdenum, niobium, and silicon produced by powder metallurgy show a certain degree of cytotoxicity. We hypothesized that the cytotoxicity is linked to the ion release from the metals. To prove this hypothesis, we assessed the cytotoxicity of titanium and titanium alloying elements in both forms of powder and bulk, using osteoblast-like SaOS(2) cells. Results indicated that the metal powders of titanium, niobium, molybdenum, and silicon are cytotoxic, and the bulk metals of silicon and molybdenum also showed cytotoxicity. Meanwhile, we established that the safe ion concentrations (below which the ion concentration is non-toxic) are 8.5, 15.5, 172.0, and 37,000.0 microg/L for molybdenum, titanium, niobium, and silicon, respectively.

The hydrogen embrittlement of titanium-based alloys

NASA Astrophysics Data System (ADS)

Tal-Gutelmacher, Ervin; Eliezer, Dan

2005-09-01

Titanium-based alloys provide an excellent combination of a high strength/weight ratio and good corrosion behavior, which makes these alloys among the most important advanced materials for a variety of aerospace, marine, industrial, and commercial applications. Although titanium is considered to be reasonably resistant to chemical attack, severe problems can arise when titanium-based alloys come in contact with hydrogen-containing environments, where they can pick up large amounts of hydrogen, especially at elevated temperatures. The severity and the extent of the hydrogen interaction with titanium-based alloys are directly related to the microstructure and composition of the titanium alloys. This paper addresses the hydrogen embrittlement of titanium-based alloys. The hydrogen-titanium interaction is reviewed, including the solubility of hydrogen in α and β phases of titanium and hydride formation. Also, the paper summarizes the detrimental effects of hydrogen in different titanium alloys.

Convergent evolution of modularity in metabolic networks through different community structures

PubMed Central

2012-01-01

Background It has been reported that the modularity of metabolic networks of bacteria is closely related to the variability of their living habitats. However, given the dependency of the modularity score on the community structure, it remains unknown whether organisms achieve certain modularity via similar or different community structures. Results In this work, we studied the relationship between similarities in modularity scores and similarities in community structures of the metabolic networks of 1021 species. Both similarities are then compared against the genetic distances. We revisited the association between modularity and variability of the microbial living environments and extended the analysis to other aspects of their life style such as temperature and oxygen requirements. We also tested both topological and biological intuition of the community structures identified and investigated the extent of their conservation with respect to the taxomony. Conclusions We find that similar modularities are realized by different community structures. We find that such convergent evolution of modularity is closely associated with the number of (distinct) enzymes in the organism’s metabolome, a consequence of different life styles of the species. We find that the order of modularity is the same as the order of the number of the enzymes under the classification based on the temperature preference but not on the oxygen requirement. Besides, inspection of modularity-based communities reveals that these communities are graph-theoretically meaningful yet not reflective of specific biological functions. From an evolutionary perspective, we find that the community structures are conserved only at the level of kingdoms. Our results call for more investigation into the interplay between evolution and modularity: how evolution shapes modularity, and how modularity affects evolution (mainly in terms of fitness and evolvability). Further, our results call for exploring new measures of modularity and network communities that better correspond to functional categorizations. PMID:22974099

Modular jet impingement assemblies with passive and active flow control for electronics cooling

DOEpatents

Zhou, Feng; Dede, Ercan Mehmet; Joshi, Shailesh

2016-09-13

Power electronics modules having modular jet impingement assembly utilized to cool heat generating devices are disclosed. The modular jet impingement assemblies include a modular manifold having a distribution recess, one or more angled inlet connection tubes positioned at an inlet end of the modular manifold that fluidly couple the inlet tube to the distribution recess and one or more outlet connection tubes positioned at an outlet end of the modular manifold that fluidly coupling the outlet tube to the distribution recess. The modular jet impingement assemblies include a manifold insert removably positioned within the distribution recess and include one or more inlet branch channels each including an impinging slot and one or more outlet branch channels each including a collecting slot. Further a heat transfer plate coupled to the modular manifold, the heat transfer plate comprising an impingement surface including an array of fins that extend toward the manifold insert.

Modular cathode assemblies and methods of using the same for electrochemical reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiedmeyer, Stanley G.; Barnes, Laurel A.; Williamson, Mark A.

Modular cathode assemblies are useable in electrolytic reduction systems and include a basket through which fluid electrolyte may pass and exchange charge with a material to be reduced in the basket. The basket can be divided into upper and lower sections to provide entry for the material. Example embodiment cathode assemblies may have any shape to permit modular placement at any position in reduction systems. Modular cathode assemblies include a cathode plate in the basket, to which unique and opposite electrical power may be supplied. Example embodiment modular cathode assemblies may have standardized electrical connectors. Modular cathode assemblies may bemore » supported by a top plate of an electrolytic reduction system. Electrolytic oxide reduction systems are operated by positioning modular cathode and anode assemblies at desired positions, placing a material in the basket, and charging the modular assemblies to reduce the metal oxide.« less

Modular cathode assemblies and methods of using the same for electrochemical reduction

DOEpatents

Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L

2014-12-02

Modular cathode assemblies are useable in electrolytic reduction systems and include a basket through which fluid electrolyte may pass and exchange charge with a material to be reduced in the basket. The basket can be divided into upper and lower sections to provide entry for the material. Example embodiment cathode assemblies may have any shape to permit modular placement at any position in reduction systems. Modular cathode assemblies include a cathode plate in the basket, to which unique and opposite electrical power may be supplied. Example embodiment modular cathode assemblies may have standardized electrical connectors. Modular cathode assemblies may be supported by a top plate of an electrolytic reduction system. Electrolytic oxide reduction systems are operated by positioning modular cathode and anode assemblies at desired positions, placing a material in the basket, and charging the modular assemblies to reduce the metal oxide.

The Current Status of Modular Coordination. A Research Correlation Conference of Building Research Institute, Division of Engineering and Industrial Research (Fall 1959).

ERIC Educational Resources Information Center

National Academy of Sciences - National Research Council, Washington, DC.

Publication of conference presentations include--(1) a brief review of current modular standard development, (2) the statistical status of modular practice, (3) availability of modular products, and (4) educational programs on modular coordination. Included are--(1) explanatory diagrams, (2) text of an open panel discussion, and (3) a list of…

Modular Design in Treaty Verification Equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macarthur, Duncan Whittemore; Benz, Jacob; Tolk, Keith

2015-01-27

It is widely believed that modular design is a good thing. However, there are often few explicit arguments, or even an agreed range of definitions, to back up this belief. In this paper, we examine the potential range of design modularity, the implications of various amounts of modularity, and the advantages and disadvantages of each level of modular construction. We conclude with a comparison of the advantages and disadvantages of each type, as well as discuss many caveats that should be observed to take advantage of the positive features of modularity and minimize the effects of the negative. The tradeoffsmore » described in this paper will be evaluated during the conceptual design to determine what amount of modularity should be included.« less

Monte Carlo simulation and film dosimetry for electron therapy in vicinity of a titanium mesh

PubMed Central

Rostampour, Masoumeh; Roayaei, Mahnaz

2014-01-01

Titanium (Ti) mesh plates are used as a bone replacement in brain tumor surgeries. In the case of radiotherapy, these plates might interfere with the beam path. The purpose of this study is to evaluate the effect of titanium mesh on the dose distribution of electron fields. Simulations were performed using Monte Carlo BEAMnrc and DOSXYZnrc codes for 6 and 10 MeV electron beams. In Monte Carlo simulation, the shape of the titanium mesh was simulated. The simulated titanium mesh was considered as the one which is used in head and neck surgery with a thickness of 0.055 cm. First, by simulation, the percentage depth dose was obtained while the titanium mesh was present, and these values were then compared with the depth dose of homogeneous phantom with no titanium mesh. In the experimental measurements, the values of depth dose with titanium mesh and without titanium mesh in various depths were measured. The experiments were performed using a RW3 phantom with GAFCHROMIC EBT2 film. The results of experimental measurements were compared with values of depth dose obtained by simulation. In Monte Carlo simulation, as well as experimental measurements, for the voxels immediately beyond the titanium mesh, the change of the dose were evaluated. For this purpose the ratio of the dose for the case with titanium to the case without titanium was calculated as a function of titanium depth. For the voxels before the titanium mesh there was always an increase of the dose up to 13% with respect to the same voxel with no titanium mesh. This is because of the increased back scattering effect of the titanium mesh. The results also showed that for the voxel right beyond the titanium mesh, there is an increased or decreased dose to soft tissues, depending on the depth of the titanium mesh. For the regions before the depth of maximum dose, there is an increase of the dose up to 10% compared to the dose of the same depth in homogeneous phantom. Beyond the depth of maximum dose, there was a 16% decrease in dose. For both 6 and 10 MeV, before the titanium mesh, there was always an increase in dose. If titanium mesh is placed in buildup region, it causes an increase of the dose and could lead to overdose of the adjacent tissue, whereas if titanium mesh is placed beyond the buildup region, it would lead to a decrease in dose compared to the homogenous tissue. PACS number: 87.53.Bn PMID:25207397

Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses.

PubMed

Witt, Florian; Gührs, Julian; Morlock, Michael M; Bishop, Nicholas E

2015-01-01

Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface.

The histological and elemental characterisation of corrosion particles from taper junctions.

PubMed

Munir, S; Oliver, R A; Zicat, B; Walter, W L; Walter, W K; Walsh, W R

2016-09-01

This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris. The CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p < 0.001). The brown/red particles were significantly higher for ASR/SROM (p < 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride. This study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage.Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016;5:370-378. DOI: 10.1302/2046-3758.59.2000507. © 2016 Munir et al.

Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses

PubMed Central

Witt, Florian; Gührs, Julian; Morlock, Michael M.; Bishop, Nicholas E.

2015-01-01

Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface. PMID:26280914

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

NASA Astrophysics Data System (ADS)

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.

Analysis of Advanced Modular Power Systems (AMPS) for Deep Space Exploration

NASA Technical Reports Server (NTRS)

Oeftering, Richard; Soeder, James F.; Beach, Ray

2014-01-01

The Advanced Modular Power Systems (AMPS) project is developing a modular approach to spacecraft power systems for exploration beyond Earth orbit. AMPS is intended to meet the need of reducing the cost of design development, test and integration and also reducing the operational logistics cost of supporting exploration missions. AMPS seeks to establish modular power building blocks with standardized electrical, mechanical, thermal and data interfaces that can be applied across multiple exploration vehicles. The presentation discusses the results of a cost analysis that compares the cost of the modular approach against a traditional non-modular approach.

In Silico Investigation of a Surgical Interface for Remote Control of Modular Miniature Robots in Minimally Invasive Surgery

PubMed Central

Zygomalas, Apollon; Giokas, Konstantinos; Koutsouris, Dimitrios

2014-01-01

Aim. Modular mini-robots can be used in novel minimally invasive surgery techniques like natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single site (LESS) surgery. The control of these miniature assistants is complicated. The aim of this study is the in silico investigation of a remote controlling interface for modular miniature robots which can be used in minimally invasive surgery. Methods. The conceptual controlling system was developed, programmed, and simulated using professional robotics simulation software. Three different modes of control were programmed. The remote controlling surgical interface was virtually designed as a high scale representation of the respective modular mini-robot, therefore a modular controlling system itself. Results. With the proposed modular controlling system the user could easily identify the conformation of the modular mini-robot and adequately modify it as needed. The arrangement of each module was always known. The in silico investigation gave useful information regarding the controlling mode, the adequate speed of rearrangements, and the number of modules needed for efficient working tasks. Conclusions. The proposed conceptual model may promote the research and development of more sophisticated modular controlling systems. Modular surgical interfaces may improve the handling and the dexterity of modular miniature robots during minimally invasive procedures. PMID:25295187

In silico investigation of a surgical interface for remote control of modular miniature robots in minimally invasive surgery.

PubMed

Zygomalas, Apollon; Giokas, Konstantinos; Koutsouris, Dimitrios

2014-01-01

Aim. Modular mini-robots can be used in novel minimally invasive surgery techniques like natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single site (LESS) surgery. The control of these miniature assistants is complicated. The aim of this study is the in silico investigation of a remote controlling interface for modular miniature robots which can be used in minimally invasive surgery. Methods. The conceptual controlling system was developed, programmed, and simulated using professional robotics simulation software. Three different modes of control were programmed. The remote controlling surgical interface was virtually designed as a high scale representation of the respective modular mini-robot, therefore a modular controlling system itself. Results. With the proposed modular controlling system the user could easily identify the conformation of the modular mini-robot and adequately modify it as needed. The arrangement of each module was always known. The in silico investigation gave useful information regarding the controlling mode, the adequate speed of rearrangements, and the number of modules needed for efficient working tasks. Conclusions. The proposed conceptual model may promote the research and development of more sophisticated modular controlling systems. Modular surgical interfaces may improve the handling and the dexterity of modular miniature robots during minimally invasive procedures.

Design strategies to address the effect of hydrophobic epitope on stability and in vitro assembly of modular virus‐like particle

PubMed Central

Tekewe, Alemu; Connors, Natalie K.; Middelberg, Anton P. J.

2016-01-01

Abstract Virus‐like particles (VLPs) and capsomere subunits have shown promising potential as safe and effective vaccine candidates. They can serve as platforms for the display of foreign epitopes on their surfaces in a modular architecture. Depending on the physicochemical properties of the antigenic modules, modularization may affect the expression, solubility and stability of capsomeres, and VLP assembly. In this study, three module designs of a rotavirus hydrophobic peptide (RV10) were synthesized using synthetic biology. Among the three synthetic modules, modularization of the murine polyomavirus VP1 with a single copy of RV10 flanked by long linkers and charged residues resulted in the expression of stable modular capsomeres. Further employing the approach of module titration of RV10 modules on each capsomere via Escherichia coli co‐expression of unmodified VP1 and modular VP1‐RV10 successfully translated purified modular capomeres into modular VLPs when assembled in vitro. Our results demonstrate that tailoring the physicochemical properties of modules to enhance modular capsomeres stability is achievable through synthetic biology designs. Combined with module titration strategy to avoid steric hindrance to intercapsomere interactions, this allows bioprocessing of bacterially produced in vitro assembled modular VLPs. PMID:27222486

Design strategies to address the effect of hydrophobic epitope on stability and in vitro assembly of modular virus-like particle.

PubMed

Tekewe, Alemu; Connors, Natalie K; Middelberg, Anton P J; Lua, Linda H L

2016-08-01

Virus-like particles (VLPs) and capsomere subunits have shown promising potential as safe and effective vaccine candidates. They can serve as platforms for the display of foreign epitopes on their surfaces in a modular architecture. Depending on the physicochemical properties of the antigenic modules, modularization may affect the expression, solubility and stability of capsomeres, and VLP assembly. In this study, three module designs of a rotavirus hydrophobic peptide (RV10) were synthesized using synthetic biology. Among the three synthetic modules, modularization of the murine polyomavirus VP1 with a single copy of RV10 flanked by long linkers and charged residues resulted in the expression of stable modular capsomeres. Further employing the approach of module titration of RV10 modules on each capsomere via Escherichia coli co-expression of unmodified VP1 and modular VP1-RV10 successfully translated purified modular capomeres into modular VLPs when assembled in vitro. Our results demonstrate that tailoring the physicochemical properties of modules to enhance modular capsomeres stability is achievable through synthetic biology designs. Combined with module titration strategy to avoid steric hindrance to intercapsomere interactions, this allows bioprocessing of bacterially produced in vitro assembled modular VLPs. © 2016 The Protein Society.

Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, And Caustic Wash Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 4 Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, T. B.; Fink, S. D.

Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), and Caustic Wash Tank (CWT) samples from several of the ?microbatches? of Integrated Salt Disposition Project (ISDP) Salt Batch (?Macrobatch?) 4 have been analyzed for {sup 238}Pu, {sup 90}Sr, {sup 137}Cs, and by inductively-coupled plasma emission spectroscopy (ICPES). Furthermore, samples from the CWT have been analyzed by a variety of methods to investigate a decline in the decontamination factor (DF) of the cesium observed at MCU. The results indicate good decontamination performance within process design expectations. While the data set is sparse, the results of this set and themore » previous set of results for Macrobatch 3 samples indicate generally consistent operations. There is no indication of a disruption in plutonium and strontium removal. The average cesium DF and concentration factor (CF) for samples obtained from Macrobatch 4 are slightly lower than for Macrobatch 3, but still well within operating parameters. The DSSHT samples show continued presence of titanium, likely from leaching of the monosodium titanate in Actinide Removal Process (ARP).« less

Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, Caustic Wash Tank And Caustic Storage Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 6 Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, T. B.

Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), Caustic Wash Tank (CWT) and Caustic Storage Tank (CST) samples from the Interim Salt Disposition Project (ISDP) Salt Batch (“Macrobatch”) 6 have been analyzed for 238Pu, 90Sr, 137Cs, and by Inductively Coupled Plasma Emission Spectroscopy (ICPES). The Pu, Sr, and Cs results from the current Macrobatch 6 samples are similar to those from comparable samples in previous Macrobatch 5. In addition the SEHT and DSSHT heel samples (i.e. ‘preliminary’) have been analyzed and reported to meet NGS Demonstration Plan requirements. From a bulk chemical point of view, the ICPESmore » results do not vary considerably between this and the previous samples. The titanium results in the DSSHT samples continue to indicate the presence of Ti, when the feed material does not have detectable levels. This most likely indicates that leaching of Ti from MST has increased in ARP at the higher free hydroxide concentrations in the current feed.« less

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

PubMed

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 < 0.05]. The surfaces of titanium cast using these two investment materials are both smooth enough to fulfill the demand of the titanium precision-casting for prosthodontic clinical use.

[Effects of laser welding on bond of porcelain fused cast pure titanium].

PubMed

Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

2006-04-01

To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

The crevice corrosion of cathodically modified titanium in chloride solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lingen, E. van der

1995-12-01

The susceptibility of titanium to crevice corrosion in low-pH chloride solutions at elevated temperatures can result in major practical problems. Although Grade 7 titanium is considered the most crevice-corrosion resistant material available for these environments, the price increase of palladium has limited the utilization of this alloy. A cost-effective titanium alloy, containing 0.2% ruthenium by mass, has been developed for use in environments of increased chloride concentration and temperature. The crevice corrosion resistance of the Ti-0.2% Ru alloy has been evaluated and compared with that of ASTM commercially pure Grade 2 titanium, Grade 7 titanium (Ti-0.12 to 0.25% palladium bymore » mass) and Grade 12 titanium (Ti-0.8% Ni-0.3% Mo). The results indicated that the cathodically modified titanium alloys, Ti-0.2% Ru and Grade 7 titanium, showed similar resistance to crevice corrosion attack in all the solutions tested, and that their behavior was significantly better than that of Grade 2 and Grade 12 titanium.« less

Modular workcells: modern methods for laboratory automation.

PubMed

Felder, R A

1998-12-01

Laboratory automation is beginning to become an indispensable survival tool for laboratories facing difficult market competition. However, estimates suggest that only 8% of laboratories will be able to afford total laboratory automation systems. Therefore, automation vendors have developed alternative hardware configurations called 'modular automation', to fit the smaller laboratory. Modular automation consists of consolidated analyzers, integrated analyzers, modular workcells, and pre- and post-analytical automation. These terms will be defined in this paper. Using a modular automation model, the automated core laboratory will become a site where laboratory data is evaluated by trained professionals to provide diagnostic information to practising physicians. Modem software information management and process control tools will complement modular hardware. Proper standardization that will allow vendor-independent modular configurations will assure success of this revolutionary new technology.

Novel antioxidant capability of titanium induced by UV light treatment.

PubMed

Ueno, Takeshi; Ikeda, Takayuki; Tsukimura, Naoki; Ishijima, Manabu; Minamikawa, Hajime; Sugita, Yoshihiko; Yamada, Masahiro; Wakabayashi, Noriyuki; Ogawa, Takahiro

2016-11-01

The intracellular production of reactive oxygen species (ROS) is a representative form of cellular oxidative stress and plays an important role in triggering adverse cellular events, such as the inflammatory reaction and delayed or compromised differentiation. Osteoblastic reaction to titanium with particular focus on ROS production remains unknown. Ultraviolet (UV) light treatment improves the physicochemical properties of titanium, specifically the induction of super hydrophilicity and removal of hydrocarbon, and eventually enhances its osteoconductivity. We hypothesized that there is a favorable regulatory change of ROS production within osteoblasts in contact with UV-treated titanium. Osteoblasts were cultured on titanium disks with or without UV-pretreatment. The intracellular production of ROS was higher on acid-etch-created rough titanium surfaces than on machine-prepared smooth ones. The ROS production was reduced by 40-50% by UV pretreatment of titanium regardless of the surface roughness. Oxidative DNA damage, as detected by 8-OHdG expression, was alleviated by 50% on UV-treated titanium surfaces. The expression of inflammatory cytokines was consistently lower in osteoblasts cultured on UV-treated titanium. ROS scavenger, glutathione, remained more without being depleted in osteoblasts on UV-treated titanium. Bio-burden test further showed that culturing osteoblasts on UV-treated titanium can significantly reduce the ROS production even with the presence of hydrogen peroxide, an oxidative stress inducer. These data suggest that the intracellular production of ROS and relevant inflammatory reaction, which unavoidably occurs in osteoblasts in contact with titanium, can be significantly reduced by UV pretreatment of titanium, implying a novel antioxidant capability of the particular titanium. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

PubMed

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.

The Modular need for the Division Signal Battalion

DTIC Science & Technology

2017-06-09

findings and analyzes them to expand on them. It is with these findings and subsequent analysis that the case studies shape the answer to the three...These case studies focus on the signal leadership development and how it occurred in the pre-modular force structure, during modularity, and the...the comparative case study research. The case studies focus on signal leader development in a pre-modular signal force, a modular signal force, and

Modular Fixturing System

NASA Technical Reports Server (NTRS)

Littell, Justin Anderson (Inventor); Street, Jon P. (Inventor)

2017-01-01

The modular fixturing system of the present invention is modular, reusable and capable of significant customization, both in terms of system radius and system height, allowing it to be arranged and rearranged in numerous unique configurations. The system includes multiple modular stanchions having stanchion shafts and stanchion feet that removably attach to apertures in a table. Angle brackets attached to the modular stanchions support shelves. These shelves in turn provide support to work pieces during fabrication processes such as welding.

A Modularized Counselor-Education Program.

ERIC Educational Resources Information Center

Miller, Thomas V.; Dimattia, Dominic J.

1978-01-01

Counselor-education programs may be enriched through the use of modularized learning experiences. This article notes several recent articles on competency-based counselor education, the concepts of simulation and modularization, and describes the process of developing a modularized master's program at the University of Bridgeport in Connecticut.…

On the classification of weakly integral modular categories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruillard, Paul; Galindo, César; Ng, Siu-Hung

In this paper we classify all modular categories of dimension 4m, where m is an odd square-free integer, and all rank 6 and rank 7 weakly integral modular categories. This completes the classification of weakly integral modular categories through rank 7. In particular, our results imply that all integral modular categories of rank at most 7 are pointed (that is, every simple object has dimension 1). All the non-integral (but weakly integral) modular categories of ranks 6 and 7 have dimension 4m, with m an odd square free integer, so their classification is an application of our main result. Themore » classification of rank 7 integral modular categories is facilitated by an analysis of the two group actions on modular categories: the Galois group of the field generated by the entries of the S-matrix and the group of invertible isomorphism classes of objects. We derive some valuable arithmetic consequences from these actions.« less

Astronaut Anna Fisher Suiting Up For NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suiting up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher Suited Up For NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suited up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher Suited Up For NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall SPace Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suited up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher Suits Up for NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suiting up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher Suiting Up For NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. MSFC's Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suiting up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher in NBS Training For Hubble Space Telescope

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher training on a mock-up of a modular section of the HST for an axial scientific instrument change out.

Astronaut Anna Fisher Suits Up For NBS Training

NASA Technical Reports Server (NTRS)

1980-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Marshall Space Flight Center's (MSFC's) Neutral Buoyancy Simulator (NBS) served as the test center for shuttle astronauts training for Hubble related missions. Shown is astronaut Anna Fisher suiting up for training on a mockup of a modular section of the HST for an axial scientific instrument change out.

Neutral Buoyancy Test - Hubble Space Telescope Scientific Instruments (SI)

NASA Technical Reports Server (NTRS)

1979-01-01

The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) to operate a long-lived space-based observatory. It was the first and flagship mission of NASA's Great Observatories program. The HST program began as an astronomical dream in the 1940s. During the 1970s and 1980s, the HST was finally designed and built becoming operational in the 1990s. The HST was deployed into a low-Earth orbit on April 25, 1990 from the cargo bay of the Space Shuttle Discovery (STS-31). The design of the HST took into consideration its length of service and the necessity of repairs and equipment replacement by making the body modular. In doing so, subsequent shuttle missions could recover the HST, replace faulty or obsolete parts and be re-released. Pictured is MSFC's Neutral Buoyancy Simulator that served as the test center for shuttle astronauts training for Hubble related missions. Shown is an astronaut training on a mock-up of a modular section of the HST in the removal and replacement of scientific instruments.

Vision and Task Assistance using Modular Wireless In Vivo Surgical Robots

PubMed Central

Platt, Stephen R.; Hawks, Jeff A.; Rentschler, Mark E.

2009-01-01

Minimally invasive abdominal surgery (laparoscopy) results in superior patient outcomes compared to conventional open surgery. However, the difficulty of manipulating traditional laparoscopic tools from outside the body of the patient generally limits these benefits to patients undergoing relatively low complexity procedures. The use of tools that fit entirely inside the peritoneal cavity represents a novel approach to laparoscopic surgery. Our previous work demonstrated that miniature mobile and fixed-based in vivo robots using tethers for power and data transmission can successfully operate within the abdominal cavity. This paper describes the development of a modular wireless mobile platform for in vivo sensing and manipulation applications. Design details and results of ex vivo and in vivo tests of robots with biopsy grasper, staple/clamp, video, and physiological sensor payloads are presented. These types of self-contained surgical devices are significantly more transportable and lower in cost than current robotic surgical assistants. They could ultimately be carried and deployed by non-medical personnel at the site of an injury to allow a remotely located surgeon to provide critical first response medical intervention irrespective of the location of the patient. PMID:19237337

Evaporation mitigation by floating modular devices

NASA Astrophysics Data System (ADS)

Hassan, M. M.; Peirson, W. L.

2016-05-01

Prolonged periods of drought and consequent evaporation from open water bodies in arid parts of Australia continue to be a threat to water availability for agricultural production. Over many parts of Australia, the annual average evaporation exceeds the annual precipitation by more than 5 times. Given its significance, it is surprising that no evaporation mitigation technique has gained widespread adoption to date. High capital and maintenance costs of manufactured products are a significant barrier to implementation. The use of directly recycled clean plastic containers as floating modular devices to mitigate evaporation has been investigated for the first time. A six-month trial at an arid zone site in Australia of this potential cost effective solution has been undertaken. The experiment was performed using clean conventional drinking water bottles as floating modules on the open water surface of 240-L tanks with three varying degrees of covering (nil, 34% and 68%). A systematic reduction in evaporation is demonstrated during the whole study period that is approximately linearly proportional to the covered surface. These results provide a potential foundation for robust evaporation mitigation with the prospect of implementing a cost-optimal design.

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

PubMed

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.

SURFACE HARDENING OF TITANIUM BY TREATMENT IN MOLTEN BORAX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minkevich, A.N.; Shul'ga, Yu.N.

1957-01-01

The surface hardening of titanium and titanium alloys by treatment in molten borax was investigated. Commercial titanium, a titanium-tungsten alloy, and an aluminum-chromium-titanium alloy were used for the experiments. To prevent oxidation of the titanium and to protect the surface, electro-chemical protection was applied, the current density being 0.1 amp/cm/sup 2/ and the the specimens were coated with a thin layer of borax. The results showed that treatment in molten borax is an effective method of increasing surface hardness. However, the strength, mmalleabiltiy, and toughness of the hardness increase is discussed. (J.S.R.)

Surface modification of titanium and titanium alloys by ion implantation.

PubMed

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.

Method for Surface Texturing Titanium Products

NASA Technical Reports Server (NTRS)

Banks, Bruce A. (Inventor)

1998-01-01

The present invention teaches a method of producing a textured surface upon an arbitrarily configured titanium or titanium alloy object for the purpose of improving bonding between the object and other materials such as polymer matrix composites and/or human bone for the direct in-growth of orthopaedic implants. The titanium or titanium alloy object is placed in an electrolytic cell having an ultrasonically agitated solution of sodium chloride therein whereby a pattern of uniform "pock mark" like pores or cavities are produced upon the object's surface. The process is very cost effective compared to other methods of producing rough surfaces on titanium and titanium alloy components. The surface textures produced by the present invention are etched directly into the parent metal at discrete sites separated by areas unaffected by the etching process. Bonding materials to such surface textures on titanium or titanium alloy can thus support a shear load even if adhesion of the bonding material is poor.

Formation of low resistivity titanium silicide gates in semiconductor integrated circuits

DOEpatents

Ishida, Emi [Sunnyvale, CA

1999-08-10

A method of forming a titanium silicide (69) includes the steps of forming a transistor having a source region (58), a drain region (60) and a gate structure (56) and forming a titanium layer (66) over the transistor. A first anneal is performed with a laser anneal at an energy level that causes the titanium layer (66) to react with the gate structure (56) to form a high resistivity titanium silicide phase (68) having substantially small grain sizes. The unreacted portions of the titanium layer (66) are removed and a second anneal is performed, thereby causing the high resistivity titanium silicide phase (68) to convert to a low resistivity titanium silicide phase (69). The small grain sizes obtained by the first anneal allow low resistivity titanium silicide phase (69) to be achieved at device geometries less than about 0.25 micron.

Electrochemical anodizing treatment to enhance localized corrosion resistance of pure titanium.

PubMed

Prando, Davide; Brenna, Andrea; Bolzoni, Fabio M; Diamanti, Maria V; Pedeferri, Mariapia; Ormellese, Marco

2017-01-26

Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

Modular interdependency in complex dynamical systems.

PubMed

Watson, Richard A; Pollack, Jordan B

2005-01-01

Herbert A. Simon's characterization of modularity in dynamical systems describes subsystems as having dynamics that are approximately independent of those of other subsystems (in the short term). This fits with the general intuition that modules must, by definition, be approximately independent. In the evolution of complex systems, such modularity may enable subsystems to be modified and adapted independently of other subsystems, whereas in a nonmodular system, modifications to one part of the system may result in deleterious side effects elsewhere in the system. But this notion of modularity and its effect on evolvability is not well quantified and is rather simplistic. In particular, modularity need not imply that intermodule dependences are weak or unimportant. In dynamical systems this is acknowledged by Simon's suggestion that, in the long term, the dynamical behaviors of subsystems do interact with one another, albeit in an "aggregate" manner--but this kind of intermodule interaction is omitted in models of modularity for evolvability. In this brief discussion we seek to unify notions of modularity in dynamical systems with notions of how modularity affects evolvability. This leads to a quantifiable measure of modularity and a different understanding of its effect on evolvability.

Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

PubMed Central

Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; Wendt, David

2014-01-01

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 titanium. PMID:25383165

Large space erectable structures - building block structures study

NASA Technical Reports Server (NTRS)

Armstrong, W. H.; Skoumal, D. E.; Straayer, J. W.

1977-01-01

A modular planar truss structure and a long slender boom concept identified as building block approaches to construction of large spacecraft configurations are described. The concepts are compatible in weight and volume goals with the Space Transportation System, use standard structural units, and represent high on-orbit productivity in terms of structural area or beam length. Results of structural trade studies involving static and dynamic analyses of a single module and rigid body deployment analyses to assess kinetics and kinematics of automatic deployment of the building block modules are presented.

Individual differences and time-varying features of modular brain architecture.

PubMed

Liao, Xuhong; Cao, Miao; Xia, Mingrui; He, Yong

2017-05-15

Recent studies have suggested that human brain functional networks are topologically organized into functionally specialized but inter-connected modules to facilitate efficient information processing and highly flexible cognitive function. However, these studies have mainly focused on group-level network modularity analyses using "static" functional connectivity approaches. How these extraordinary modular brain structures vary across individuals and spontaneously reconfigure over time remain largely unknown. Here, we employed multiband resting-state functional MRI data (N=105) from the Human Connectome Project and a graph-based modularity analysis to systematically investigate individual variability and dynamic properties in modular brain networks. We showed that the modular structures of brain networks dramatically vary across individuals, with higher modular variability primarily in the association cortex (e.g., fronto-parietal and attention systems) and lower variability in the primary systems. Moreover, brain regions spontaneously changed their module affiliations on a temporal scale of seconds, which cannot be simply attributable to head motion and sampling error. Interestingly, the spatial pattern of intra-subject dynamic modular variability largely overlapped with that of inter-subject modular variability, both of which were highly reproducible across repeated scanning sessions. Finally, the regions with remarkable individual/temporal modular variability were closely associated with network connectors and the number of cognitive components, suggesting a potential contribution to information integration and flexible cognitive function. Collectively, our findings highlight individual modular variability and the notable dynamic characteristics in large-scale brain networks, which enhance our understanding of the neural substrates underlying individual differences in a variety of cognition and behaviors. Copyright © 2017 Elsevier Inc. All rights reserved.

Titanium Brazing for Structures and Survivability

DTIC Science & Technology

2007-05-01

materials, such as ceramics. This work focuses on vacuum brazing of titanium (both Ti- 6Al - 4V and commercially pure titanium ) and the effect of...such as ceramics. This work focuses on vacuum brazing of titanium (both Ti- 6Al - 4V and commercially pure titanium ) and the effect of processing...Suzumura, and Onzawa, reported the joining of Ti- 6Al - 4V and CP titanium alloys with zirconium-rich braze alloys.5 They found that these alloys could

Laminate armor and related methods

DOEpatents

Chu, Henry S; Lillo, Thomas M; Zagula, Thomas M

2013-02-26

Laminate armor and methods of manufacturing laminate armor. Specifically, laminate armor plates comprising a commercially pure titanium layer and a titanium alloy layer bonded to the commercially pure titanium outer layer are disclosed, wherein an average thickness of the titanium alloy inner layer is about four times an average thickness of the commercially pure titanium outer layer. In use, the titanium alloy layer is positioned facing an area to be protected. Additionally, roll-bonding methods for manufacturing laminate armor plates are disclosed.

Titanium: Industrial Base, Price Trends, and Technology Initiatives

DTIC Science & Technology

2009-01-01

respectively.3 All titanium metal production begins with rutile (titanium oxide, or TiO2). High-titania slag , produced by ilmen- ite smelting, is the first...Ilmenite ores are used in iron production. They leave a TiO2-rich slag , which is usually upgraded to be used in titanium production. 4 According to the...and least expensive process for producing titanium sponge, has four major steps. First, rutile con- centrate or synthetic rutile (titanium slag ) is

The promotion of osseointegration of titanium surfaces by coating with silk protein sericin.

PubMed

Nayak, Sunita; Dey, Tuli; Naskar, Deboki; Kundu, Subhas C

2013-04-01

A promising strategy to influence the osseointegration process around orthopaedic titanium implants is the immobilization of bioactive molecules. This recruits appropriate interaction between the surface and the tissue by directing cells adhesion, proliferation, differentiation and active matrix remodelling. In this study, we aimed to investigate the functionalization of metallic implant titanium with silk protein sericin. Titanium surface was immobilized with non-mulberry Antheraea mylitta sericin using glutaraldehyde as crosslinker. To analyse combinatorial effects the sericin immobilized titanium was further conjugated with integrin binding peptide sequence Arg-Gly-Asp (RGD) using ethyl (dimethylaminopropyl) carbodiimide and N-hydroxysulfosuccinimide as coupling agents. The surface of sericin immobilized titanium was characterized biophysically. Osteoblast-like cells were cultured on sericin and sericin/RGD functionalized titanium and found to be more viable than those on pristine titanium. The enhanced adhesion, proliferation, and differentiation of osteoblast cells were observed. RT-PCR analysis showed that mRNA expressions of bone sialoprotein, osteocalcin and alkaline phosphatase were upregulated in osteoblast cells cultured on sericin and sericin/RGD immobilized titanium substrates. Additionally, no significant amount of pro-inflammatory cytokines TNF-α, IL-1β and nitric oxide production were recorded when macrophages cells and osteoblast-macrophages co culture cells were grown on sericin immobilized titanium. The findings demonstrate that the sericin immobilized titanium surfaces are potentially useful bioactive coated materials for titanium-based medical implants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterisation of titanium-titanium boride composites processed by powder metallurgy techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selva Kumar, M., E-mail: sel_mcet@yahoo.co.in; Chandrasekar, P.; Chandramohan, P.

2012-11-15

In this work, a detailed characterisation of titanium-titanium boride composites processed by three powder metallurgy techniques, namely, hot isostatic pressing, spark plasma sintering and vacuum sintering, was conducted. Two composites with different volume percents of titanium boride reinforcement were used for the investigation. One was titanium with 20% titanium boride, and the other was titanium with 40% titanium boride (by volume). Characterisation was performed using X-ray diffraction, electron probe micro analysis - energy dispersive spectroscopy and wavelength dispersive spectroscopy, image analysis and scanning electron microscopy. The characterisation results confirm the completion of the titanium boride reaction. The results reveal themore » presence of titanium boride reinforcement in different morphologies such as needle-shaped whiskers, short agglomerated whiskers and fine plates. The paper also discusses how mechanical properties such as microhardness, elastic modulus and Poisson's ratio are influenced by the processing techniques as well as the volume fraction of the titanium boride reinforcement. - Highlights: Black-Right-Pointing-Pointer Ti-TiB composites were processed by HIP, SPS and vacuum sintering. Black-Right-Pointing-Pointer The completion of Ti-TiB{sub 2} reaction was confirmed by XRD, SEM and EPMA studies. Black-Right-Pointing-Pointer Hardness and elastic properties of Ti-TiB composites were discussed. Black-Right-Pointing-Pointer Processing techniques were compared with respect to their microstructure.« less

Recovery of titanium values from titanium grinding swarf by electric furnace smelting

DOEpatents

Gerdemann, Stephen J.; White, Jack C.

1999-01-01

A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

Recovery of titanium values from titanium grinding swarf by electric furnace smelting

DOEpatents

Gerdemann, Stephen J.; White, Jack C.

1998-01-01

A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

Recovery of titanium values from titanium grinding swarf by electric furnace smelting

DOEpatents

Gerdemann, S.J.; White, J.C.

1998-08-04

A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag. 1 fig.

Ball bearings comprising nickel-titanium and methods of manufacture thereof

NASA Technical Reports Server (NTRS)

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.

Production of Diesel Engine Turbocharger Turbine from Low Cost Titanium Powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muth, T. R.; Mayer, R.

2012-05-04

Turbochargers in commercial turbo-diesel engines are multi-material systems where usually the compressor rotor is made of aluminum or titanium based material and the turbine rotor is made of either a nickel based superalloy or titanium, designed to operate under the harsh exhaust gas conditions. The use of cast titanium in the turbine section has been used by Cummins Turbo Technologies since 1997. Having the benefit of a lower mass than the superalloy based turbines; higher turbine speeds in a more compact design can be achieved with titanium. In an effort to improve the cost model, and develop an industrial supplymore » of titanium componentry that is more stable than the traditional aerospace based supply chain, the Contractor has developed component manufacturing schemes that use economical Armstrong titanium and titanium alloy powders and MgR-HDH powders. Those manufacturing schemes can be applied to compressor and turbine rotor components for diesel engine applications with the potential of providing a reliable supply of titanium componentry with a cost and performance advantage over cast titanium.« less

Microstructure analysis and wear behavior of titanium cermet femoral head with hard TiC layer.

PubMed

Luo, Yong; Ge, Shirong; Liu, Hongtao; Jin, Zhongmin

2009-12-11

Titanium cermet was successfully synthesized and formed a thin gradient titanium carbide coating on the surface of Ti6Al4V alloy by using a novel sequential carburization under high temperature, while the titanium cermet femoral head was produced. The titanium cermet phase and surface topography were characterized with X-ray diffraction (XRD) and backscattered electron imaging (BSE). And then the wear behavior of titanium cermet femoral head was investigated by using CUMT II artificial joint hip simulator. The surface characterization indicates that carbon effectively diffused into the titanium alloys and formed a hard TiC layer on the Ti6Al4V alloys surface with a micro-porous structure. The artificial hip joint experimental results show that titanium cermet femoral head could not only improve the wear resistance of artificial femoral head, but also decrease the wear of UHMWPE joint cup. In addition, the carburized titanium alloy femoral head could effectively control the UHMWPE debris distribution, and increase the size of UHMWPE debris. All of the results suggest that titanium cermet is a prospective femoral head material in artificial joint.

Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

PubMed

Doi, H; Harrori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

2001-02-01

The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases.

Modular Apparatus and Method for Attaching Multiple Devices

NASA Technical Reports Server (NTRS)

Okojie, Robert S (Inventor)

2015-01-01

A modular apparatus for attaching sensors and electronics is disclosed. The modular apparatus includes a square recess including a plurality of cavities and a reference cavity such that a pressure sensor can be connected to the modular apparatus. The modular apparatus also includes at least one voltage input hole and at least one voltage output hole operably connected to each of the plurality of cavities such that voltage can be applied to the pressure sensor and received from the pressure sensor.

Robotic hand with modular extensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salisbury, Curt Michael; Quigley, Morgan

A robotic device is described herein. The robotic device includes a frame that comprises a plurality of receiving regions that are configured to receive a respective plurality of modular robotic extensions. The modular robotic extensions are removably attachable to the frame at the respective receiving regions by way of respective mechanical fuses. Each mechanical fuse is configured to trip when a respective modular robotic extension experiences a predefined load condition, such that the respective modular robotic extension detaches from the frame when the load condition is met.

Ultrasonic longitudinal waves to monitor the integration of titanium rods with host bone

NASA Astrophysics Data System (ADS)

Wang, Wentao; Lynch, Jerome P.

2017-04-01

Osseointegrated prostheses which integrate the prosthesis directly to the limb bone are being developed for patients that are unable to wear traditional socket prostheses. While osseointegration of the prosthesis offers amputees improvement in their quality of life, there remains a need to better understand the integration process that occurs between the bone and the prosthesis. Quantification of the degree of integration is important to track the recuperation process of the amputee, guide physical therapy regimes, and to identify when the state of integration may change (due to damage to the bone). This study explores the development of an assessment strategy for quantitatively assessing the degree of integration between an osseointegrated prosthesis and host bone. Specifically, the strategy utilizes a titanium rod prosthesis as a waveguide with guided waves used to assess the degree of integration. By controlling waveforms launched by piezoelectric wafers bonded on the percutaneous tip of the prosthesis, body waves are introduced into the waveguide with wave reflections at the boneprosthesis interface recorded by the same array. Changes in wave energy are correlated to changes at the contact interface between the titanium rod and the bone material. Both simulation and experimental tests are presented in this paper. Experimental testing is performed using a high-density polyethylene (HDPE) host because the elastic modulus and density of HDPE are close to that of human and animal bone. Results indicate high sensitivity of the longitudinal wave energy to rod penetration depth and confinement stress issued by the host bone.

Synthesis of polycaprolactone-titanium oxide multilayer films by nanosecond laser pulses and electrospinning technique for better implant fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naghshine, Babak B.; Cosman, James A.; Kiani, Amirkianoosh, E-mail: a.kiani@unb.ca

In this study, a combination of electrospinning and laser texturing is introduced as a novel method for increasing the biocompatibility of metal implants. Besides having a rough laser treated surface, the implant benefits from the high porosity and better wettability of an electrospun fibrous structure, which is a more favorable environment for cell proliferation. Titanium samples were patterned using a nanosecond laser beam and were placed as collectors in an electrospinning machine. They were then soaked in simulated body fluid for four weeks. Energy Dispersive X-ray and X-Ray Diffraction results indicate significantly more hydroxyapatite formation on laser treated samples withmore » nanoscale fibers deposited on their surface. This shows that having a laser treated surface underneath the fibrous layer can improve short-term biocompatibility even before degradation of fibers. The thermal conductivity of the electrospun layer, measured using a Hot Disk Transient Plane Source instrument and computer code, was shown to be considerably lower than that of titanium and very close to bone. The presence of this layer can therefore be beneficial in making the implant more compatible to a biological medium. In case of dental implants, it was shown that this layer can act as a thermal barrier while a hot beverage is consumed and it can decrease the temperature rise by about 60%, which avoids any possible damage to newly formed cells during the healing period.« less

Effect of CeO2 and Y2O3 on microstructure, bioactivity and degradability of laser cladding CaO-SiO2 coating on titanium alloy.

PubMed

Li, H C; Wang, D G; Chen, C Z; Weng, F

2015-03-01

To solve the lack of strength of bulk biomaterials for load-bearing applications and improve the bioactivity of titanium alloy (Ti-6Al-4V), CaO-SiO2 coatings on titanium alloy were fabricated by laser cladding technique. The effect of CeO2 and Y2O3 on microstructure and properties of laser cladding coating was analyzed. The cross-section microstructure of ceramic layer from top to bottom gradually changes from cellular-dendrite structure to compact cellular crystal. The addition of CeO2 or Y2O3 refines the microstructure of the ceramic layer in the upper and middle regions. The refining effect on the grain is related to the kinds of additives and their content. The coating is mainly composed of CaTiO3, CaO, α-Ca2(SiO4), SiO2 and TiO2. Y2O3 inhibits the formation of CaO. After soaking in simulated body fluid (SBF), the calcium phosphate layer is formed on the coating surface, indicating the coating has bioactivity. After soaking in Tris-HCl solution, the samples doped with CeO2 or Y2O3 present a lower weight loss, indicating the addition of CeO2 or Y2O3 improves the degradability of laser cladding sample. Copyright © 2015 Elsevier B.V. All rights reserved.

P2 porous titanium implants improve tendon healing in an acute rat supraspinatus repair model.

PubMed

Tucker, Jennica J; Gordon, Joshua A; Zanes, Robert C; Zuskov, Andrey; Vinciguerra, John D; Bloebaum, Roy D; Soslowsky, Louis J

2017-03-01

Current techniques in rotator cuff repair often lack structural integrity. P 2 porous titanium-coated constructs (DJO Surgical, Austin, TX, USA) promote osseointegration and soft tissue ingrowth. This study examined the ability of this material to improve the structural integrity of supraspinatus tendon repair in a rat model. We hypothesized that P 2 implants placed at the tendon-to-bone interface would improve mechanical and histologic measures of supraspinatus healing. Forty rats underwent supraspinatus repairs with P 2 implants in 1 shoulder and standard repair in the other. Rats were humanely killed at time 0 (n = 3), 2 weeks (n = 8), 4 weeks (n = 15), and 12 weeks (n = 14). Tendon-to-bone composite specimens were harvested and evaluated mechanically and histologically. Tendon cross-sectional area was decreased in the P 2 implant group at 4 weeks, percentage of relaxation was increased at 2 weeks, elastic modulus was increased at 4 weeks, and maximum load and maximum stress were both increased at 2 and 4 weeks. Histologic analysis revealed no foreign body reactions within or around the P 2 implant, and healthy viable bone was visible within the P 2 implant. The results support our hypothesis, specifically in early healing, in this randomized controlled animal study. These data support the use of P 2 porous titanium implants to improve tendon-to-bone healing. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Retrieval analysis of titanium nitride (TiN) coated prosthetic femoral heads articulating with polyethylene.

PubMed

Łapaj, Łukasz; Wendland, Justyna; Markuszewski, Jacek; Mróz, Adrian; Wiśniewski, Tomasz

2015-03-01

Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1-56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Experimental and Computational Study of Interphase Properties and Mechanics in Titanium Metal Matrix Composites at Elevated Temperatures

DTIC Science & Technology

2005-03-01

size of the interphase [22-24]. Yang and Jeng [45], in a study of the titanium aluminides Ti-24-11 and Ti-25-10, and a metastable beta titanium Ti-15-3... Titanium Aluminide Matrix Composites," Workshop proceedings on Titanium Matrix Components, P.R. Smith and W.C. Revelos, eds., Wright-Patterson AFB...Experimental and Computational Study of Interphase Properties and Mechanics in Titanium Metal Matrix Composites at Elevated Temperatures Final Report

Titanium disilicide formation by sputtering of titanium on heated silicon substrate

NASA Astrophysics Data System (ADS)

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

Utilization of gas-atomized titanium and titanium-aluminide powder

NASA Astrophysics Data System (ADS)

Moll, John H.

2000-05-01

A gas-atomization process has been developed producing clean, high-quality, prealloyed spherical titanium and titanium-aluminide powder. The powder is being used to manufacture hot-isostatically pressed consolidated shapes for aerospace and nonaerospace allocations. These include gamma titanium-aluminide sheet and orthorhombic titanium-aluminide wire as well as niche markets, such as x-ray drift standards and sputtering targets. The powder is also being used in specialized processes, including metal-matrix composites, laser forming, and metal-injection molding.

Titanium Alloy Strong Back for IXO Mirror Segments

NASA Technical Reports Server (NTRS)

Byron, Glenn P.; Kai-Wang, Chan

2011-01-01

A titanium-alloy mirror-holding fixture called a strong back allows the temporary and permanent bonding of a 50 degree D263 glass x-ray mirror (IXO here stands for International X-ray Observatory). The strong back is used to hold and position a mirror segment so that mounting tabs may be bonded to the mirror with ultra-low distortion of the optical surface. Ti-15%Mo alloy was the material of choice for the strong back and tabs because the coefficient of thermal expansion closely matches that of the D263 glass and the material is relatively easy to machine. This invention has the ability to transfer bonded mounting points from a temporary location on the strong back to a permanent location on the strong back with minimal distortion. Secondly, it converts a single mirror segment into a rigid body with an acceptable amount of distortion of the mirror, and then maneuvers that rigid body into optical alignment such that the mirror segment can be bonded into a housing simulator or mirror module. Key problems are that the mirrors are 0.4-mm thick and have a very low coefficient of thermal expansion (CTE). Because the mirrors are so thin, they are very flexible and are easily distorted. When permanently bonding the mirror, the goal is to achieve a less than 1-micron distortion. Temperature deviations in the lab, which have been measured to be around 1 C, have caused significant distortions in the mirror segment.

An animal model to evaluate skin-implant-bone integration and gait with a prosthesis directly attached to the residual limb

PubMed Central

Farrell, Brad J; Prilutsky, Boris I; Kistenberg, Robert S; Dalton, John F; Pitkin, Mark

2014-01-01

Background Despite the number of advantages of bone-anchored prostheses, their use in patients is limited due to the lack of complete skin-implant integration. The objective of the present study was to develop an animal model that would permit both detailed investigations of gait with a bone-anchored limb prosthesis and histological analysis of the skin-implant-bone interface after physiological loading of the implant during standing and walking. Methods Full-body mechanics of walking in two cats was recorded and analyzed before and after implantation of a percutaneous porous titanium pylon into the right tibia and attachment of a prosthesis. The rehabilitation procedures included initial limb casting, progressively increasing loading of implant, and standing and locomotor training. Detailed histological analysis of bone and skin ingrowth into implant was performed at the end of the study. Findings The two animals adopted the bone-anchored prosthesis for standing and locomotion, although loads on the prosthetic limb during walking decreased by 22% and 62%, respectively, 4 months after implantation. The animals shifted body weight to the contralateral side and increased propulsion forces by the contralateral hindlimb. Histological analysis of the limb implants demonstrated bone and skin ingrowth. Interpretation The developed animal model to study prosthetic gait and tissue integration with the implant demonstrated that porous titanium implants may permit bone and skin integration and prosthetic gait with a prosthesis. Future studies with this model will help optimize the implant and prosthesis properties. PMID:24405567

Modular femoral neck fracture after primary total hip arthroplasty.

PubMed

Sotereanos, Nicholas G; Sauber, Timothy J; Tupis, Todd T

2013-01-01

The use of modular femoral stems in primary total hip arthroplasty has increased considerably in recent years. These modular components offer the surgeon the ability to independently alter version, offset, and length of the femoral component of a hip arthroplasty. This increases the surgeon's ability to accurately recreate the relevant anatomy but increases the possibilities of corrosion and fracture. Multiple case reports have highlighted fractures of these modular components. We present a case of a fracture of a modular design that has had no previously reported modular neck fractures. The patient was informed that data concerning the case would be submitted, and he consented. Copyright © 2013 Elsevier Inc. All rights reserved.

Modular properties of 6d (DELL) systems

NASA Astrophysics Data System (ADS)

Aminov, G.; Mironov, A.; Morozov, A.

2017-11-01

If super-Yang-Mills theory possesses the exact conformal invariance, there is an additional modular invariance under the change of the complex bare charge [InlineMediaObject not available: see fulltext.]. The low-energy Seiberg-Witten prepotential ℱ( a), however, is not explicitly invariant, because the flat moduli also change a - → a D = ∂ℱ/∂ a. In result, the prepotential is not a modular form and depends also on the anomalous Eisenstein series E 2. This dependence is usually described by the universal MNW modular anomaly equation. We demonstrate that, in the 6 d SU( N) theory with two independent modular parameters τ and \\widehat{τ} , the modular anomaly equation changes, because the modular transform of τ is accompanied by an ( N -dependent!) shift of \\widehat{τ} and vice versa. This is a new peculiarity of double-elliptic systems, which deserves further investigation.

Towards a Formal Basis for Modular Safety Cases

NASA Technical Reports Server (NTRS)

Denney, Ewen; Pai, Ganesh

2015-01-01

Safety assurance using argument-based safety cases is an accepted best-practice in many safety-critical sectors. Goal Structuring Notation (GSN), which is widely used for presenting safety arguments graphically, provides a notion of modular arguments to support the goal of incremental certification. Despite the efforts at standardization, GSN remains an informal notation whereas the GSN standard contains appreciable ambiguity especially concerning modular extensions. This, in turn, presents challenges when developing tools and methods to intelligently manipulate modular GSN arguments. This paper develops the elements of a theory of modular safety cases, leveraging our previous work on formalizing GSN arguments. Using example argument structures we highlight some ambiguities arising through the existing guidance, present the intuition underlying the theory, clarify syntax, and address modular arguments, contracts, well-formedness and well-scopedness of modules. Based on this theory, we have a preliminary implementation of modular arguments in our toolset, AdvoCATE.

Brain modularity controls the critical behavior of spontaneous activity.

PubMed

Russo, R; Herrmann, H J; de Arcangelis, L

2014-03-13

The human brain exhibits a complex structure made of scale-free highly connected modules loosely interconnected by weaker links to form a small-world network. These features appear in healthy patients whereas neurological diseases often modify this structure. An important open question concerns the role of brain modularity in sustaining the critical behaviour of spontaneous activity. Here we analyse the neuronal activity of a model, successful in reproducing on non-modular networks the scaling behaviour observed in experimental data, on a modular network implementing the main statistical features measured in human brain. We show that on a modular network, regardless the strength of the synaptic connections or the modular size and number, activity is never fully scale-free. Neuronal avalanches can invade different modules which results in an activity depression, hindering further avalanche propagation. Critical behaviour is solely recovered if inter-module connections are added, modifying the modular into a more random structure.

Why Go Modular? A Review of Modular A-Level Mathematics.

ERIC Educational Resources Information Center

Taverner, Sally; Wright, Martin

1997-01-01

Attitudes, academic intentions, and attainment of students gaining a grade in A-level (Advanced level) mathematics were compared for those who followed a modular course and those assessed at the end of two years of study. Overall, the final grades of those assessed modularly were half a grade higher. (JOW)

On Classification of Modular Categories by Rank: Table A.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruillard, Paul; Ng, Siu-Hung; Rowell, Eric C.

2016-04-10

The feasibility of a classification-by-rank program for modular categories follows from the Rank-Finiteness Theorem. We develop arithmetic, representation theoretic and algebraic methods for classifying modular categories by rank. As an application, we determine all possible fusion rules for all rank=5 modular categories and describe the corresponding monoidal equivalence classes.

46 CFR 181.450 - Independent modular smoke detecting units.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Independent modular smoke detecting units. 181.450... Independent modular smoke detecting units. (a) An independent modular smoke detecting unit must: (1) Meet UL 217 (incorporated by reference, see 46 CFR 175.600) and be listed as a “Single Station Smoke detector...

46 CFR 181.450 - Independent modular smoke detecting units.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Independent modular smoke detecting units. 181.450... Independent modular smoke detecting units. (a) An independent modular smoke detecting unit must: (1) Meet UL 217 (incorporated by reference, see 46 CFR 175.600) and be listed as a “Single Station Smoke detector...

46 CFR 181.450 - Independent modular smoke detecting units.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Independent modular smoke detecting units. 181.450... Independent modular smoke detecting units. (a) An independent modular smoke detecting unit must: (1) Meet UL 217 (incorporated by reference, see 46 CFR 175.600) and be listed as a “Single Station Smoke detector...

46 CFR 181.450 - Independent modular smoke detecting units.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Independent modular smoke detecting units. 181.450... Independent modular smoke detecting units. (a) An independent modular smoke detecting unit must: (1) Meet UL 217 (incorporated by reference, see 46 CFR 175.600) and be listed as a “Single Station Smoke detector...

46 CFR 181.450 - Independent modular smoke detecting units.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Independent modular smoke detecting units. 181.450... Independent modular smoke detecting units. (a) An independent modular smoke detecting unit must: (1) Meet UL 217 (incorporated by reference, see 46 CFR 175.600) and be listed as a “Single Station Smoke detector...

Investigation on the Oxidation and Reduction of Titanium in Molten Salt with the Soluble TiC Anode

NASA Astrophysics Data System (ADS)

Wang, Shulan; Wan, Chaopin; Liu, Xuan; Li, Li

2015-12-01

To reveal the oxidation process of titanium from TiC anode and the reduction mechanism of titanium ions in molten NaCl-KCl, the polarization curve of TiC anode in molten NaCl-KCl and cyclic voltammograms of the molten salt after polarization were studied. Investigation on the polarization curve shows that titanium can be oxidized and dissociated from the TiC anode at very low potential. The cyclic voltammograms demonstrated that the reduction reaction of titanium ions in the molten salt is a one-step process. By potentiostatic electrolysis, dendritic titanium is obtained on the steel plate. The work promotes the understanding on the process of electrochemical oxidization/dissociation of titanium from TiC anode and the reduction mechanism of titanium ions in molten salt.

Ultra-rapid photocatalytic activity of Azadirachta indica engineered colloidal titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Sankar, Renu; Rizwana, Kadarmohideen; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2015-08-01

Titanium dioxide nanoparticles were effectively synthesized from aqueous leaf extract of Azadirachta indica under pH and temperature-dependent condition. 5 mM titanium isopropoxide solution worked as a primary source for the synthesis of titanium dioxide nanoparticles. The green synthesized titanium dioxide nanoparticles were confirmed by UV-Vis spectroscopy. Fourier transform infrared spectrum of synthesized titanium dioxide nanoparticles authorized the presence of bioactive compounds in the leaf extract, which may play a role as capping and reducing agent. The high-resolution scanning electron microscopy and dynamic light scattering analyses results showed the interconnected spherical in shape titanium dioxide nanoparticles having a mean particle size of 124 nm and a zeta potential of -24 mV. Besides, the colloidal titanium dioxide nanoparticles energetically degrade the industrially harmful methyl red dye under bright sunlight.

Unraveling the disease consequences and mechanisms of modular structure in animal social networks

PubMed Central

Leu, Stephan T.; Cross, Paul C.; Hudson, Peter J.; Bansal, Shweta

2017-01-01

Disease risk is a potential cost of group living. Although modular organization is thought to reduce this cost in animal societies, empirical evidence toward this hypothesis has been conflicting. We analyzed empirical social networks from 43 animal species to motivate our study of the epidemiological consequences of modular structure in animal societies. From these empirical studies, we identified the features of interaction patterns associated with network modularity and developed a theoretical network model to investigate when and how subdivisions in social networks influence disease dynamics. Contrary to prior work, we found that disease risk is largely unaffected by modular structure, although social networks beyond a modular threshold experience smaller disease burden and longer disease duration. Our results illustrate that the lowering of disease burden in highly modular social networks is driven by two mechanisms of modular organization: network fragmentation and subgroup cohesion. Highly fragmented social networks with cohesive subgroups are able to structurally trap infections within a few subgroups and also cause a structural delay to the spread of disease outbreaks. Finally, we show that network models incorporating modular structure are necessary only when prior knowledge suggests that interactions within the population are highly subdivided. Otherwise, null networks based on basic knowledge about group size and local contact heterogeneity may be sufficient when data-limited estimates of epidemic consequences are necessary. Overall, our work does not support the hypothesis that modular structure universally mitigates the disease impact of group living. PMID:28373567

Unraveling the disease consequences and mechanisms of modular structure in animal social networks

USGS Publications Warehouse

Sah, Pratha; Leu, Stephan T.; Cross, Paul C.; Hudson, Peter J.; Bansal, Shweta

2017-01-01

Disease risk is a potential cost of group living. Although modular organization is thought to reduce this cost in animal societies, empirical evidence toward this hypothesis has been conflicting. We analyzed empirical social networks from 43 animal species to motivate our study of the epidemiological consequences of modular structure in animal societies. From these empirical studies, we identified the features of interaction patterns associated with network modularity and developed a theoretical network model to investigate when and how subdivisions in social networks influence disease dynamics. Contrary to prior work, we found that disease risk is largely unaffected by modular structure, although social networks beyond a modular threshold experience smaller disease burden and longer disease duration. Our results illustrate that the lowering of disease burden in highly modular social networks is driven by two mechanisms of modular organization: network fragmentation and subgroup cohesion. Highly fragmented social networks with cohesive subgroups are able to structurally trap infections within a few subgroups and also cause a structural delay to the spread of disease outbreaks. Finally, we show that network models incorporating modular structure are necessary only when prior knowledge suggests that interactions within the population are highly subdivided. Otherwise, null networks based on basic knowledge about group size and local contact heterogeneity may be sufficient when data-limited estimates of epidemic consequences are necessary. Overall, our work does not support the hypothesis that modular structure universally mitigates the disease impact of group living.

Unraveling the disease consequences and mechanisms of modular structure in animal social networks.

PubMed

Sah, Pratha; Leu, Stephan T; Cross, Paul C; Hudson, Peter J; Bansal, Shweta

2017-04-18

Disease risk is a potential cost of group living. Although modular organization is thought to reduce this cost in animal societies, empirical evidence toward this hypothesis has been conflicting. We analyzed empirical social networks from 43 animal species to motivate our study of the epidemiological consequences of modular structure in animal societies. From these empirical studies, we identified the features of interaction patterns associated with network modularity and developed a theoretical network model to investigate when and how subdivisions in social networks influence disease dynamics. Contrary to prior work, we found that disease risk is largely unaffected by modular structure, although social networks beyond a modular threshold experience smaller disease burden and longer disease duration. Our results illustrate that the lowering of disease burden in highly modular social networks is driven by two mechanisms of modular organization: network fragmentation and subgroup cohesion. Highly fragmented social networks with cohesive subgroups are able to structurally trap infections within a few subgroups and also cause a structural delay to the spread of disease outbreaks. Finally, we show that network models incorporating modular structure are necessary only when prior knowledge suggests that interactions within the population are highly subdivided. Otherwise, null networks based on basic knowledge about group size and local contact heterogeneity may be sufficient when data-limited estimates of epidemic consequences are necessary. Overall, our work does not support the hypothesis that modular structure universally mitigates the disease impact of group living.

Molecular genetic and biochemical responses in human airway epithelial cell cultures exposed to titanium nanoparticles in vitro.

PubMed

Aydın, Elanur; Türkez, Hasan; Hacımüftüoğlu, Fazıl; Tatar, Abdulgani; Geyikoğlu, Fatime

2017-07-01

Titanium nanoparticles (NPs) have very wide application areas such as paint, cosmetics, pharmaceuticals, and biomedical applications. And, to translate these nanomaterials to the clinic and industrial domains, their safety needs to be verified, particularly in terms of genotoxicity and cytotoxicity. Therefore, in this study, we aimed to investigate of cytotoxicity and changes in gene expression profiles influenced by commonly titanium (as titanium carbide, titanium carbo-nitride, titanium (II) oxide, titanium (III) oxide, titanium (IV) oxide, titanium nitride, titanium silicon oxide) NPs in human alveolar epithelial (HPAEpiC) and pharynx (HPPC) cell lines in vitro since inhalation is an important pathway for exposure to these NPs. HPAEpiC and HPPC cells were treated with titanium (0-100 µg/mL), NPs for 24 and 48 h, and then cytotoxicity was detected by, [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT), uptake of neutral red (NR) and lactate dehydrogenase (LDH) release assays, while genotoxicity was also analyzed by cDNA array - RT-PCR assay. According to the results of MTT, NR and LDH assays, all tested NPs induced cytotoxicity on both HPAEpiC and HPPC cells in a time- and dose-dependent manner. Determining and analyzing the gene expression profiles of HPAEpiC and HPPC cells, titanium NPs showed more changes in genes related to DNA damage or repair, oxidative stress, and apoptosis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2056-2064, 2017. © 2017 Wiley Periodicals, Inc.

In-vitro assessment of oxidative stress generated by orthodontic archwires.

PubMed

Spalj, Stjepan; Mlacovic Zrinski, Magda; Tudor Spalj, Vedrana; Ivankovic Buljan, Zorana

2012-05-01

Several metals undergo redox cycling, producing free radicals and generating oxidative stress. The purpose of this study was to investigate in-vitro oxidative stress of orthodontic archwires made of various alloys. Mouse fibroblast cells L929 were exposed to 6 types of archwires, and the concentration of the oxidative stress marker 8-hydroxy-2'-deoxyguanosine in DNA was evaluated. Trypan blue dye was used in the determination of cell viability and numbers. Standard nickel-titanium archwires generated the highest oxidative stress, significantly higher than all other wires and the controls (P <0.05), and coated nickel-titanium, copper-nickel-titanium, and cobalt-chromium were lower than nickel-titanium (P <0.05), but higher than titanium-molybdenum and the negative and absolute controls (P <0.05). Titanium-molybdenum and stainless steel generated the lowest stress. Nickel-titanium induced the lowest viability, lower than the negative and absolute controls and all other wires (P <0.05) except titanium-molybdenum. Stainless steel showed the highest viability. Nickel-titanium produced the highest inhibition of cell growth, higher than all samples (P <0.05) except the positive control and cobalt-chromium. The lowest inhibition was observed in stainless steel and titanium-molybdenum, lower than nickel-titanium, cobalt-chromium, and the positive control (P <0.05). All orthodontic archwires generate oxidative stress in vitro. Stainless steel archwires have the highest and nickel-titanium the lowest biocompatibility. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Modular architecture of protein structures and allosteric communications: potential implications for signaling proteins and regulatory linkages

PubMed Central

del Sol, Antonio; Araúzo-Bravo, Marcos J; Amoros, Dolors; Nussinov, Ruth

2007-01-01

Background Allosteric communications are vital for cellular signaling. Here we explore a relationship between protein architectural organization and shortcuts in signaling pathways. Results We show that protein domains consist of modules interconnected by residues that mediate signaling through the shortest pathways. These mediating residues tend to be located at the inter-modular boundaries, which are more rigid and display a larger number of long-range interactions than intra-modular regions. The inter-modular boundaries contain most of the residues centrally conserved in the protein fold, which may be crucial for information transfer between amino acids. Our approach to modular decomposition relies on a representation of protein structures as residue-interacting networks, and removal of the most central residue contacts, which are assumed to be crucial for allosteric communications. The modular decomposition of 100 multi-domain protein structures indicates that modules constitute the building blocks of domains. The analysis of 13 allosteric proteins revealed that modules characterize experimentally identified functional regions. Based on the study of an additional functionally annotated dataset of 115 proteins, we propose that high-modularity modules include functional sites and are the basic functional units. We provide examples (the Gαs subunit and P450 cytochromes) to illustrate that the modular architecture of active sites is linked to their functional specialization. Conclusion Our method decomposes protein structures into modules, allowing the study of signal transmission between functional sites. A modular configuration might be advantageous: it allows signaling proteins to expand their regulatory linkages and may elicit a broader range of control mechanisms either via modular combinations or through modulation of inter-modular linkages. PMID:17531094

Modular assembly for supporting, straining, and directing flow to a core in a nuclear reactor

DOEpatents

Pennell, William E.

1977-01-01

A reactor core support arrangement for supporting, straining, and providing fluid flow to the core and periphery of a nuclear reactor during normal operation. A plurality of removable inlet modular units are contained within permanent liners in the lower supporting plate of the reactor vessel lower internals. During normal operation (1) each inlet modular unit directs main coolant flow to a plurality of core assemblies, the latter being removably supported in receptacles in the upper portion of the modular unit and (2) each inlet modular unit may direct bypass flow to a low pressure annular region of the reactor vessel. Each inlet modular unit may include special fluid seals interposed between mating surfaces of the inlet modular units and the core assemblies and between the inlet modular units and the liners, to minimize leakage and achieve an hydraulic balance. Utilizing the hydraulic balance, the modular units are held in the liners and the assemblies are held in the modular unit receptacles by their own respective weight. Included as part of the permanent liners below the horizontal support plate are generally hexagonal axial debris barriers. The axial debris barriers collectively form a bottom boundary of a secondary high pressure plenum, the upper boundary of which is the bottom surface of the horizontal support plate. Peripheral liners include radial debris barriers which collectively form a barrier against debris entry radially. During normal operation primary coolant inlet openings in the liner, below the axial debris barriers, pass a large amount of coolant into the inlet modular units, and secondary coolant inlet openings in the portion of the liners within the secondary plenum pass a small amount of coolant into the inlet modular units. The secondary coolant inlet openings also provide alternative coolant inlet flow paths in the unlikely event of blockage of the primary inlet openings. The primary inlet openings have characteristics which limit the entry of debris and minimize the potential for debris entering the primary inlets blocking the secondary inlets from inside the modular unit.

Titanium hermetic seals

DOEpatents

Brow, Richard K.; Watkins, Randall D.

1995-07-04

Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

Titanium hermetic seals

DOEpatents

Brow, Richard K.; Watkins, Randall D.

1995-01-01

Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

Adhesive-Bonded Tab Attaches Thermocouples to Titanium

NASA Technical Reports Server (NTRS)

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.

Allergic contact dermatitis caused by titanium screws and dental implants.

PubMed

Hosoki, Maki; Nishigawa, Keisuke; Miyamoto, Youji; Ohe, Go; Matsuka, Yoshizo

2016-07-01

Titanium has been considered to be a non-allergenic material. However, several studies have reported cases of metal allergy caused by titanium-containing materials. We describe a 69-year-old male for whom significant pathologic findings around dental implants had never been observed. He exhibited allergic symptoms (eczema) after orthopedic surgery. The titanium screws used in the orthopedic surgery that he underwent were removed 1 year later, but the eczema remained. After removal of dental implants, the eczema disappeared completely. Titanium is used not only for medical applications such as plastic surgery and/or dental implants, but also for paints, white pigments, photocatalysts, and various types of everyday goods. Most of the usage of titanium is in the form of titanium dioxide. This rapid expansion of titanium-containing products has increased percutaneous and permucosal exposure of titanium to the population. In general, allergic risk of titanium material is smaller than that of other metal materials. However, we suggest that pre-implant patients should be asked about a history of hypersensitivity reactions to metals, and patch testing should be recommended to patients who have experienced such reactions. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Cold Spraying of Armstrong Process Titanium Powder for Additive Manufacturing

NASA Astrophysics Data System (ADS)

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.

Real-time assessment of surface interactions with titanium passivation layer by surface plasmon resonance

PubMed Central

Hirata, Isao; Yoshida, Yasuhiro; Nagaoka, Noriyuki; Hiasa, Kyou; Abe, Yasuhiko; Maekawa, Kenji; Kuboki, Takuo; Akagawa, Yasumasa; Suzuki, Kazuomi; Van Meerbeek, Bart; Messersmith, Phillip B.; Okazaki, Masayuki

2011-01-01

The high corrosion resistance and strength-to-density ratio makes titanium widely used in major industry, but also in a gamut of medical applications. Here we report for the first time on our development of a titanium passivation layer sensor that makes use of surface plasmon resonance (SPR). The deposited titanium metal layer on the sensor was passivated in air, like titanium medical devices. Our ‘Ti-SPR sensor’ enables analysis of biomolecules interactions with the passivated surface of titanium in real time. As a proof of concept, corrosion of titanium passivation layer exposed to acid was monitored in real time. Also, the Ti-SPR sensor can accurately measure the time-dependence of protein adsorption onto titanium passivation layer with a sub-nanogram per square millimeter accuracy. Besides such SPR analyses, an SPR-imaging (SPRI) enables real-time assessment of chemical surface processes that occur simultaneously at ‘multiple independent spots’ on the Ti-SPR sensor, such as acid-corrosion or adhesion of cells. Our Ti-SPR sensor will therefore be very useful to study titanium-corrosion phenomena and biomolecular titanium-surface interactions with application in a broad range of industrial and biomedical fields. PMID:22154862

[The influences of crystallized compositions in the porcelain on bonding strength of titanium to porcelain].

PubMed

Mo, A; Wang, J; Liao, Y; Cen, Y; Shi, X

2001-12-01

Sufficient porcelain-titanium bond is a vital factor determining the clinical performance of titanium-porcelain restorations. The purpose of this study was to investigate the effects of self-preparation La-porcelain composition on the porcelain-titanium bonding strength and to compare with the Vita Titankeramik. The present study examines 5 different recipes of porcelain by weight%: SiO2, 12%-17%; LaO2, 7%-10%; Al2O3, 9%-14%; B2O3, 23%-31%; CaO, 6%-8%; K2O, 2%-3%; SrO, 2%-4%; Na2O, 1%-3%; SnO2, 8%-10%; ZrO2, 3%-5%; TiO2, 6%-8%. Specimens were tested in push type shear with a universal testing machine. Scanning electron microscopy (SEM) and electron probe microanalyzer (EPMA) were employed to reveal the microstructures and diffusion of elements in the interfacial regions between the porcelain coating and titanium to the bond strength when fired at 800 degrees C. The ratios of crystallized compositions had significant influences on the porcelain-titanium bond strength (P < 0.05). La-porcelain had the highest shear bond strength (37.76 MPa). The shear bond strength of the Vita Titankeramik to titanium was 20.18 MPa. The results of SEM revealed integrity of porcelain-titanium joints in La-porcelain and a greater amount of porosity in the interface of Vita Titankeramik to titanium. EPMA analysis demonstrated the aggregation of Si and Sn in the interfacial regions and their diffusion into the titanium. Chemical compositions of porcelain and ratios of crystallized compositions play the important role in the titanium porcelain bond. La-porcelain had the highest shear bond strength and good porcelain-titanium joints. La-porcelain is a new-style low fusing porcelain/titanium system.

Deep drawability of Ti/resin/Ti laminated sheet

NASA Astrophysics Data System (ADS)

Hardada, Yasunroi; Hattori, Shuji

2017-10-01

Aiming to enhance functionality of titanium cup, the formability of titanium/resin/titanium laminated sheet by deep drawing was investigated. Although pure titanium has excellent corrosion resistance, the density of titanium is higher than that of light metals, such as aluminum and magnesium. Part of the titanium cup made of resin allows for weight reduction of the cup. Furthermore, the clad cup is more likely to have heat retention and protection against vibration characteristics. In the experiment, the materials were pure titanium and polycarbonate. The initial thickness of the sheet was 0.2 to 0.5 mm in thickness. A total plate thickness of the blank was 1.0 to 1.5 mm in thickness. The blank diameter is 70 mm. The laminated sheet was constituted by interposing resin between two titanium sheets. Each sheet in stacked condition was not joined each other. In the deep drawing process, the laminated sheet was employed and a flat sheet blank was formed into a circle by a punch. For the prevention of seizure in contact area between a drawing tool and titanium, titanium blank was treated by oxide coating. By this method, the fresh and clean titanium is not in direct contact with the die during the forming due to the existence of the oxide layer. The deep drawing was carried out to investigate the formability. The laminated sheet was successfully drawn without the cracks. The section of the drawn cup was observed to examine a formability of the resin sheet. The reduction rate of the thickness was less than 10%. It was found that the titanium/resin/titanium clad cup was successfully drawn.

Portable modular detection system

DOEpatents

Brennan, James S [Rodeo, CA; Singh, Anup [Danville, CA; Throckmorton, Daniel J [Tracy, CA; Stamps, James F [Livermore, CA

2009-10-13

Disclosed herein are portable and modular detection devices and systems for detecting electromagnetic radiation, such as fluorescence, from an analyte which comprises at least one optical element removably attached to at least one alignment rail. Also disclosed are modular detection devices and systems having an integrated lock-in amplifier and spatial filter and assay methods using the portable and modular detection devices.

Jack Rabbit Pretest Shadowplate Drawings For TATB IHE Model Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hart, M M; McDaniel, D W

The Jack Rabbit Pretest (PT) series consisted of 5 focused hydrodynamic experiments 2021E PT3, PT4, PT5, PT6, and PT7. They were fired in March and April of 2008 at the Contained Firing Facility, Site 300, Lawrence Livermore National Laboratory, Livermore, California. These experiments measured deadzone formation and impulse gradients created during the detonation of TATB based insensitive high explosive. When setting up computer simulations of the Jack Rabbit Pretest series, the modeler or code developer can execute simulations with increasing degrees of refinement using detail found in the shadowplate design. The easiest way to get started is by treating themore » shadowplate in each experiment as a monolithic homogeneous piece of stainless steel. The simulation of detonation would begin as a point initiation below the center, bottom surface of the shadowplate. The detonation running through the ultrafine TATB booster can be simulated using program burn and then switched over to a reactive flow detonation model as the detonation front crosses the boundary into the main charge LX-17 IHE. A modeler wanting to further refine the simulation and progression of shock through the shadowplate can use the more detailed shadowplate design information presented in this document. The source drawings are included in Appendix A of this document. Their titles and drawing numbers are listed. Each experiment's shadowplate consists of two major components. A 303 stainless steel shape that defines the outer dimensions of shadowplate and a cylindrical 303 stainless steel detonator housing that is located in a closely machined pocket in the shape. The SIMPLE ASSY drawing accurately represents the dimensions of the outer shape, it's machined cylindrical pocket, and detonator body which is treated as a monolithic, homogeneous piece of stainless steel. The detonator body cross section shows an accurately dimensioned void where the slapper flyer barrel, LX-16 (pressed PETN) pellet, and pellet can flyer barrel are located. The FULL ASSY drawing accurately represents the dimensions of the outer shadowplate shape and it's machined pocket. The detonator dimensions and materials are detailed in cross section and exploded view. All diameters, thicknesses, and materials are called out in the drawing. You will notice that the detonator includes a multilayer slapper assembly with two layers of electrically insulating Kapton sandwiching the copper foil bridge circuit. The Kapton insulated circuit is sandwiched between two thin stainless steel sheets. This slapper assembly is secured to the detonator body with two screws. There is a 0.25 mm gap between the slapper assembly and the outer shadowplate shape. The stainless steel detonator body contains an off-center titanium wheel. This titanium wheel is secured to the detonator body with one screw and two pins to maintain position and orientation of the pellet can assembly in the center of the detonator body. The titanium wheel contains a tantalum/tungsten washer and pellet can assembly. The pellet can assembly consists of a pressed LX-16 initiator pellet contained in an extruded aluminum foil can. It may be useful for the modeler to include some of the details of the shadowplate and detonator design to further refine simulations of the Jack Rabbit Pretest experiments. These details may be relevant to the progression of shock originating from the PETN initiation pellet and ultrafine TATB booster that propagates through the shadowplate.« less

Modularity-like objective function in annotated networks

NASA Astrophysics Data System (ADS)

Xie, Jia-Rong; Wang, Bing-Hong

2017-12-01

We ascertain the modularity-like objective function whose optimization is equivalent to the maximum likelihood in annotated networks. We demonstrate that the modularity-like objective function is a linear combination of modularity and conditional entropy. In contrast with statistical inference methods, in our method, the influence of the metadata is adjustable; when its influence is strong enough, the metadata can be recovered. Conversely, when it is weak, the detection may correspond to another partition. Between the two, there is a transition. This paper provides a concept for expanding the scope of modularity methods.

Modular organization and hospital performance.

PubMed

Kuntz, Ludwig; Vera, Antonio

2007-02-01

The concept of modularization represents a modern form of organization, which contains the vertical disaggregation of the firm and the use of market mechanisms within hierarchies. The objective of this paper is to examine whether the use of modular structures has a positive effect on hospital performance. The empirical section makes use of multiple regression analyses and leads to the main result that modularization does not have a positive effect on hospital performance. However, the analysis also finds out positive efficiency effects of two central ideas of modularization, namely process orientation and internal market mechanisms.

Modular analysis of biological networks.

PubMed

Kaltenbach, Hans-Michael; Stelling, Jörg

2012-01-01

The analysis of complex biological networks has traditionally relied on decomposition into smaller, semi-autonomous units such as individual signaling pathways. With the increased scope of systems biology (models), rational approaches to modularization have become an important topic. With increasing acceptance of de facto modularity in biology, widely different definitions of what constitutes a module have sparked controversies. Here, we therefore review prominent classes of modular approaches based on formal network representations. Despite some promising research directions, several important theoretical challenges remain open on the way to formal, function-centered modular decompositions for dynamic biological networks.

Full characterization of modular values for finite-dimensional systems

NASA Astrophysics Data System (ADS)

Ho, Le Bin; Imoto, Nobuyuki

2016-06-01

Kedem and Vaidman obtained a relationship between the spin-operator modular value and its weak value for specific coupling strengths [14]. Here we give a general expression for the modular value in the n-dimensional Hilbert space using the weak values up to (n - 1)th order of an arbitrary observable for any coupling strength, assuming non-degenerated eigenvalues. For two-dimensional case, it shows a linear relationship between the weak value and the modular value. We also relate the modular value of the sum of observables to the weak value of their product.

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.

PubMed

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 brackets, more precise manufacturing technique should be improved to get a more smoother surface finish.

Performance Evaluation of Titanium Ion Optics for the NASA 30 cm Ion Thruster

NASA Technical Reports Server (NTRS)

Soulas, George C.

2001-01-01

The results of performance tests with titanium ion optics were presented and compared to those of molybdenum ion optics. Both titanium and molybdenum ion optics were initially operated until ion optics performance parameters achieved steady state values. Afterwards, performance characterizations were conducted. This permitted proper performance comparisons of titanium and molybdenum ion optics. Ion optics' performance A,as characterized over a broad thruster input power range of 0.5 to 3.0 kW. All performance parameters for titanium ion optics of achieved steady state values after processing 1200 gm of propellant. Molybdenum ion optics exhibited no burn-in. Impingement-limited total voltages for titanium ion optics where up to 55 V greater than those for molybdenum ion optics. Comparisons of electron backstreaming limits as a function of peak beam current density for molybdenum and titanium ion optics demonstrated that titanium ion optics operated with a higher electron backstreaming limit than molybdenum ion optics for a given peak beam current density. Screen grid ion transparencies for titanium ion optics were as much as 3.8 percent lower than those for molybdenum ion optics. Beam divergence half-angles that enclosed 95 percent of the total beam current for titanium ion optics were within 1 to 3 deg. of those for molybdenum ion optics. All beam divergence thrust correction factors for titanium ion optics were within 1 percent of those with molybdenum ion optics.

High porous titanium scaffolds showed higher compatibility than lower porous beta-tricalcium phosphate scaffolds for regulating human osteoblast and osteoclast differentiation.

PubMed

Hirota, Makoto; Hayakawa, Tohru; Shima, Takaki; Ametani, Akihiro; Tohnai, Iwai

2015-04-01

We compared osteoblast and osteoclast differentiation when using beta-tricalcium phosphate (βTCP) and titanium scaffolds by investigating human mesenchymal stem cells (hMSCs) and osteoclast progenitor cell activities. hMSCs were cultured for 7, 14, and 21days on titanium scaffolds with 60%, 73%, and 87% porosity and on βTCP scaffolds with 60% and 75% porosity. Human osteoclast progenitor cells were cultured with osteoblast for 14 and 21days on 87% titanium and 75% βTCP scaffolds. Viable cell numbers with 60% and 73% titanium were higher than with 87% titanium and βTCP scaffolds (P<0.05). An 87% titanium scaffold resulted in the highest osteocalcin production with calcification on day 14 (P<0.01) in titanium scaffolds. All titanium scaffolds resulted in higher osteocalcin production on days 7 and 14 compared to βTCP scaffolds (P<0.01). Osteoblasts cultured on 87% titanium scaffolds suppressed osteoclast differentiation on day 7 but enhanced osteoclast differentiation on day 14 compared to 75% βTCP scaffolds (P<0.01). These findings concluded that high porosity titanium scaffolds could enhance progression of hMSC/osteoblast differentiation and regulated osteoclast differentiation cooperating with osteoblast differentiation for calcification as compared with lower porous βTCP. Copyright © 2015 Elsevier B.V. All rights reserved.

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

PubMed

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.

Cellular uptake of titanium and vanadium from addition of salts or fretting corrosion in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurer, A.M.; Merritt, K.; Brown, S.A.

1994-02-01

The use of titanium and titanium-6% aluminum-4% vanadium alloy for dental and orthopedic implants has increased in the last decade. The implants are presumed to be compatible because oseointegration, bony apposition, and cell attachment are known. However, the cellular association of titanium and vanadium have remained unknown. This study examined the uptake of salts or fretting corrosion products. Titanium was not observed to be toxic to the cells. Vanadium was toxic at levels greater than 10[mu]g/mL. The percentage of cellular association of titanium was shown to be about 10 times that of vanadium. The percentage of cellular association of eithermore » element was greater from fretting corrosion than from the addition of salts. The presence of vanadium did not affect the cellular uptake of titanium. The presence of titanium decreased the cell association of vanadium.« less

Causal Factors of Weld Porosity in Gas Tungsten Arc Welding of Powder-Metallurgy-Produced Titanium Alloys

NASA Astrophysics Data System (ADS)

Muth, T. R.; Yamamoto, Y.; Frederick, D. A.; Contescu, C. I.; Chen, W.; Lim, Y. C.; Peter, W. H.; Feng, Z.

2013-05-01

An investigation was undertaken using gas tungsten arc (GTA) welding on consolidated powder metallurgy (PM) titanium (Ti) plate to identify the causal factors behind observed porosity in fusion welding. Tramp element compounds of sodium and magnesium, residual from the metallothermic reduction of titanium chloride used to produce the titanium, were remnant in the starting powder and were identified as gas-forming species. PM-titanium made from revert scrap, where sodium and magnesium were absent, showed fusion weld porosity, although to a lesser degree. We show that porosity was attributable to hydrogen from adsorbed water on the surface of the powders prior to consolidation. The removal and minimization of both adsorbed water on the surface of titanium powder and the residues from the reduction process prior to consolidation of titanium powders are critical for achieving equivalent fusion welding success similar to that seen in wrought titanium produced via the Kroll process.

THE SMALL BODY GEOPHYSICAL ANALYSIS TOOL

NASA Astrophysics Data System (ADS)

Bercovici, Benjamin; McMahon, Jay

2017-10-01

The Small Body Geophysical Analysis Tool (SBGAT) that we are developing aims at providing scientists and mission designers with a comprehensive, easy to use, open-source analysis tool. SBGAT is meant for seamless generation of valuable simulated data originating from small bodies shape models, combined with advanced shape-modification properties.The current status of SBGAT is as follows:The modular software architecture that was specified in the original SBGAT proposal was implemented in the form of two distinct packages: a dynamic library SBGAT Core containing the data structure and algorithm backbone of SBGAT, and SBGAT Gui which wraps the former inside a VTK, Qt user interface to facilitate user/data interaction. This modular development facilitates maintenance and addi- tion of new features. Note that SBGAT Core can be utilized independently from SBGAT Gui.SBGAT is presently being hosted on a GitHub repository owned by SBGAT’s main developer. This repository is public and can be accessed at https://github.com/bbercovici/SBGAT. Along with the commented code, one can find the code documentation at https://bbercovici.github.io/sbgat-doc/index.html. This code documentation is constently updated in order to reflect new functionalities.SBGAT’s user’s manual is available at https://github.com/bbercovici/SBGAT/wiki. This document contains a comprehensive tutorial indicating how to retrieve, compile and run SBGAT from scratch.Some of the upcoming development goals are listed hereafter. First, SBGAT's dynamics module will be extented: the PGM algorithm is the only type of analysis method currently implemented. Future work will therefore consists in broadening SBGAT’s capabilities with the Spherical Harmonics Expansion of the gravity field and the calculation of YORP coefficients. Second, synthetic measurements will soon be available within SBGAT. The software should be able to generate synthetic observations of different type (radar, lightcurve, point clouds,...) from the shape model currently manipulated. Finally, shape interaction capabilities will be added to SBGAT GUI, as it will be augmented with these functionalities using built-in VTK interaction methods.

Microstructural Evolution in Friction Stir Welding of Ti-5111

DTIC Science & Technology

2010-08-01

titanium and titanium aluminide alloys—an overview.” Materials Science and Engineering A243 (1998) 1-24 [Semiatin 1999] S.L. Semiatin, V...ABSTRACT Titanium and titanium alloys have shown excellent mechanical, physical, and corrosion properties. To address the needs of future naval...Texture; Phase Transformation Ti-5111 Titanium 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 174 19a

Process for reproducibly preparing titanium subhydride

DOEpatents

Carlson, Richard S.

1982-01-01

Titanium subhydride is produced in a reactor by heating a selected amount of finely divided titanium compound at a selected temperature for a selected period of time under dynamic vacuum conditions. Hydrogen is removed substantially uniformly from each powder grain and there is produced a subhydride of substantially uniform titanium-hydrogen composition. Selection of the amount, temperature and time produces a subhydride of selected titanium-hydrogen composition.

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

NASA Astrophysics Data System (ADS)

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.

GRAVIDY, a GPU modular, parallel direct-summation N-body integrator: dynamics with softening

NASA Astrophysics Data System (ADS)

Maureira-Fredes, Cristián; Amaro-Seoane, Pau

2018-01-01

A wide variety of outstanding problems in astrophysics involve the motion of a large number of particles under the force of gravity. These include the global evolution of globular clusters, tidal disruptions of stars by a massive black hole, the formation of protoplanets and sources of gravitational radiation. The direct-summation of N gravitational forces is a complex problem with no analytical solution and can only be tackled with approximations and numerical methods. To this end, the Hermite scheme is a widely used integration method. With different numerical techniques and special-purpose hardware, it can be used to speed up the calculations. But these methods tend to be computationally slow and cumbersome to work with. We present a new graphics processing unit (GPU), direct-summation N-body integrator written from scratch and based on this scheme, which includes relativistic corrections for sources of gravitational radiation. GRAVIDY has high modularity, allowing users to readily introduce new physics, it exploits available computational resources and will be maintained by regular updates. GRAVIDY can be used in parallel on multiple CPUs and GPUs, with a considerable speed-up benefit. The single-GPU version is between one and two orders of magnitude faster than the single-CPU version. A test run using four GPUs in parallel shows a speed-up factor of about 3 as compared to the single-GPU version. The conception and design of this first release is aimed at users with access to traditional parallel CPU clusters or computational nodes with one or a few GPU cards.

Thin films and uses

DOEpatents

Baskaran, Suresh; Graff, Gordon L.; Song, Lin

1998-01-01

The invention provides a method for synthesizing a titanium oxide-containing film comprising the following steps: (a) preparing an aqueous solution of a titanium chelate with a titanium molarity in the range of 0.01M to 0.6M. (b) immersing a substrate in the prepared solution, (c) decomposing the titanium chelate to deposit a film on the substrate. The titanium chelate maybe decomposed acid, base, temperature or other means. A preferred method provides for the deposit of adherent titanium oxide films from C2 to C5 hydroxy carboxylic acids. In another aspect the invention is a novel article of manufacture having a titanium coating which protects the substrate against ultraviolet damage. In another aspect the invention provides novel semipermeable gas separation membranes, and a method for producing them.

Characterization and morphology of prepared titanium dioxide nanofibers by electrospinning.

PubMed

Park, Ju-Young; Lee, In-Hwa

2010-05-01

Dispersed titanium dioxide in polymer nanofibers were prepared by sol-gel processing and electrospinning techniques using titanium isopropoxide (TiP)/polyvinylpyrrolidone (PVP) solution. The prepared titanium dioxide nanofibers were characterized by FE-SEM, TEM, XRD, and FT-IR. Pure titanium dioxide nanofibers were obtained from calcination of inorganic-organic composite fiber. The diameter of titanium oxide nanofibers were in the range of 70 nm to 150 nm. Prepared titanium dioxide nanofibers show rough surface and rather small diameter compare with TiP/PVP composite nanofibers. After calcined at 500 degrees C, TiO2 nanofibers convert into anatase and rutile mixed phased from amorphous structure. Calcination of these composite fibers above 600 degrees C resulted in pure rutile TiO2 nanofibers.

Removal of titanium plates coated with anodic titanium oxide ceramic: retrospective study.

PubMed

Velich, Norbert; Németh, Zsolt; Suba, Csongor; Szabó, György

2002-09-01

Transformation of the surface of metallic titanium with titanium oxides prepared in various ways is a modern procedure. For more than 15 years, the authors have been utilizing fixing elements coated with titanium oxide ceramics, prepared by anodic oxidation and thermal treatment, for purposes of jawbone osteosynthesis. The aim of the authors' work was to assess the extent to which the titanium oxide ceramic coating influences the fate of the plates used for osteosynthesis within the human organism, in regard to the possible need for their removal. During a 5-year period, 108 of 1,396 plates coated with anodic titanium oxide had to be removed for various reasons: plate exposure (47), osteomyelitis (25), palpable swelling and tenderness (21), patient request for psychological reasons (13), or fracture of the plate (2). In none of these 108 cases was metallosis observed, which otherwise is reported relatively frequently in the vicinity of traditional titanium fixing elements, nor was any tissue damage connected with the surface of the plates. The results indicate the favorable properties of the titanium oxide ceramic surface.

On the role of sparseness in the evolution of modularity in gene regulatory networks

PubMed Central

2018-01-01

Modularity is a widespread property in biological systems. It implies that interactions occur mainly within groups of system elements. A modular arrangement facilitates adjustment of one module without perturbing the rest of the system. Therefore, modularity of developmental mechanisms is a major factor for evolvability, the potential to produce beneficial variation from random genetic change. Understanding how modularity evolves in gene regulatory networks, that create the distinct gene activity patterns that characterize different parts of an organism, is key to developmental and evolutionary biology. One hypothesis for the evolution of modules suggests that interactions between some sets of genes become maladaptive when selection favours additional gene activity patterns. The removal of such interactions by selection would result in the formation of modules. A second hypothesis suggests that modularity evolves in response to sparseness, the scarcity of interactions within a system. Here I simulate the evolution of gene regulatory networks and analyse diverse experimentally sustained networks to study the relationship between sparseness and modularity. My results suggest that sparseness alone is neither sufficient nor necessary to explain modularity in gene regulatory networks. However, sparseness amplifies the effects of forms of selection that, like selection for additional gene activity patterns, already produce an increase in modularity. That evolution of new gene activity patterns is frequent across evolution also supports that it is a major factor in the evolution of modularity. That sparseness is widespread across gene regulatory networks indicates that it may have facilitated the evolution of modules in a wide variety of cases. PMID:29775459