Streptococcus mutans attachment on a cast titanium surface

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Sicknan Soares da Rocha

2009-03-01

Full Text Available This study examined by means of scanning electron microscopy (SEM, the attachment of Streptococcus mutans and the corrosion of cast commercially pure titanium, used in dental dentures. The sample discs were cast in commercially pure titanium using the vacuum-pressure machine (Rematitan System. The surfaces of each metal were ground and polished with sandpaper (#300-4000 and alumina paste (0.3 µm. The roughness of the surface (Ra was measured using the Surfcorder rugosimeter SE 1700. Four coupons were inserted separately into Falcon tubes contained Mueller Hinton broth inoculated with S. mutans ATCC 25175 (10(9 cuf and incubated at 37 °C. The culture medium was changed every three days during a 365-day period, after which the falcons were prepared for observations by SEM. The mean Ra value of CP Ti was 0.1527 µm. After S. mutans biofilm removal, pits of corrosion were observed. Despite the low roughness, S. mutans attachment and biofilm formation was observed, which induced a surface corrosion of the cast pure titanium.

Influence of Surface Roughness on the Fatigue Life of Nickel-Titanium Rotary Endodontic Instruments.

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Lopes, Hélio P; Elias, Carlos N; Vieira, Márcia V B; Vieira, Victor T L; de Souza, Letícia Chaves; Dos Santos, Alexander Lopes

2016-06-01

The goal of the present study was to evaluate the influence of surface grooves (peaks and valleys) resulting from machining during the manufacturing process of polished and unpolished nickel-titanium BR4C endodontic files on the fatigue life of the instruments. Ten electropolished and 10 unpolished endodontic files were provided by the manufacturer. Specimens were from the same batch, but the unpolished instruments were removed from the production line before surface treatment. The instruments were evaluated with a profilometer to quantify the surface roughness on the working part of the instruments. Then the files were subjected to rotating bending fatigue tests. Analysis with the profilometer showed that surface grooves were deeper on the unpolished instruments compared with their electropolished counterparts. In the rotating bending fatigue test, the mean and standard deviation for the number of cycles until fracture (NCF) were greater for instruments with less pronounced grooves. Student t test revealed significant differences in all tests (P instruments tested; the smaller the groove depth, the greater the NCF. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effect of irrigation on surface roughness and fatigue resistance of controlled memory wire nickel-titanium instruments.

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Cai, J-J; Tang, X-N; Ge, J-Y

2017-07-01

To investigate the effect of irrigation on the surface roughness and fatigue resistance of HyFlex and M3 controlled memory (CM) wire nickel-titanium instruments. Two new files of each brand were analysed by atomic force microscopy (AFM). Then, the instruments were dynamically immersed in either 5.25% sodium hypochlorite (NaOCl) or 17% ethylene diamine tetraacetic acid (EDTA) solution for 10 min, followed by AFM analysis. The roughness average (Ra) and root mean square (RMS) values were analysed statistically using an independent sample t-test. Then, 36 files of each brand were randomly assigned to three groups (n = 12). Group 1 (the control group) was composed of new instruments. Groups 2 and 3 were dynamically immersed in 5.25% NaOCl and 17% EDTA solutions for 10 min, respectively. The number of rotations to failure for various groups was analysed using the one-way analysis of variance software. For M3 files, the Ra and RMS values significantly increased (P  0.05) NaOCl. The resistance to cyclic fatigue of both HyFlex and M3 files did not significantly decrease (P > 0.05) by immersing in 5.25% NaOCl and 17% EDTA solutions. Except the HyFlex files immersed in NaOCl, the surface roughness of other files exposed to irrigants increased. However, a change in the surface tomography of CM wire instruments caused by contact with irrigants for 10 min did not trigger a decrease in cyclic fatigue resistance. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Influence of surface modification on friction coefficient of the titanium-elastomer couple.

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Chladek, Wiesław; Hadasik, Eugeniusz; Chladek, Grzegorz

2007-01-01

This paper presents the results of a study of the friction coefficient of titanium-elastomer couple. The study was carried out with a view to potential future utilization of its results for constructing retentive elements of implanted prostheses. Changes in the friction force were recorded while removing titanium specimens placed between two silicone counter specimens made of Ufi Gel. The influence of the titanium specimen movement speed in relation that of to the counter specimens and the influence of clamping force on the friction force were assessed. Additionally, the surface roughness of titanium specimens differed; in one case, titanium was coated with polyethylene. The effect of introducing artificial saliva between the cooperating surfaces on the friction force and friction coefficient was analyzed as well. Based on the characteristics recorded, the possibilities of shaping the friction coefficient have been assessed, since it is the friction coefficient that determines effective operation of a friction couple through increasing the titanium specimen roughness. The artificial saliva being introduced between the specimens reduces considerably the friction coefficient through a change of the phenomenon model. An increase in the pressure force for the specimens of high roughness entails a reduction of the friction coefficient. The study carried out allows us to identify the roughness parameters, which in turn will enable obtaining the prescribed retention force for friction/membrane couplings.

Influence of titanium-substrate roughness on Ca–P–O thin films grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Ananda Sagari, A.R., E-mail: arsagari@gmail.com [Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyväskylä (Finland); Malm, Jari [Department of Chemistry, P.O. Box 16100, FI-00076 Aalto University, Espoo (Finland); Laitinen, Mikko [Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyväskylä (Finland); Rahkila, Paavo [Department of Biology of Physical Activity, P.O. Box 35, FIN-40014 University of Jyväskylä (Finland); Hongqiang, Ma [Department of Health Sciences, P.O. Box 35 (L), FIN-40014 University of Jyväskylä (Finland); Putkonen, Matti [Department of Chemistry, P.O. Box 16100, FI-00076 Aalto University, Espoo (Finland); Beneq Oy, P.O. Box 262, FI-01511 Vantaa (Finland); Karppinen, Maarit [Department of Chemistry, P.O. Box 16100, FI-00076 Aalto University, Espoo (Finland); Whitlow, Harry J.; Sajavaara, Timo [Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyväskylä (Finland)

2013-03-01

Amorphous Ca–P–O films were deposited on titanium substrates using atomic layer deposition, while maintaining a uniform Ca/P pulsing ratio of 6/1 with varying number of atomic layer deposition cycles starting from 10 up to 208. Prior to film deposition the titanium substrates were mechanically abraded using SiC abrasive paper of 600, 1200, 2000 grit size and polished with 3 μm diamond paste to obtain surface roughness R{sub rms} values of 0.31 μm, 0.26 μm, 0.16 μm, and 0.10 μm, respectively. The composition and film thickness of as-deposited amorphous films were studied using Time-Of-Flight Elastic Recoil Detection Analysis. The results showed that uniform films could be deposited on rough metal surfaces with a clear dependence of substrate roughness on the Ca/P atomic ratio of thin films. The in vitro cell-culture studies using MC3T3 mouse osteoblast showed a greater coverage of cells on the surface polished with diamond paste in comparison to rougher surfaces after 24 h culture. No statistically significant difference was observed between Ca–P–O coated and un-coated Ti surfaces for the measured roughness value. The deposited 50 nm thick films did not dissolve during the cell culture experiment. - Highlights: ► Atomic layer deposition of Ca–P–O films on abraded Ti substrate ► Surface analysis using Time-Of-Flight Elastic Recoil Detection Analysis ► Dependence of substrate roughness on the Ca/P atomic ratio of thin films ► An increase in Ca/P atomic ratio with decreasing roughness ► Mouse osteoblast showed greater coverage of cells in polished surface.

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

Science.gov (United States)

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.

Antimicrobial effect, frictional resistance, and surface roughness of stainless steel orthodontic brackets coated with nanofilms of silver and titanium oxide: a preliminary study.

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Ghasemi, Tania; Arash, Valiollah; Rabiee, Sayed Mahmood; Rajabnia, Ramazan; Pourzare, Amirhosein; Rakhshan, Vahid

2017-06-01

Nano-silver and nano-titanium oxide films can be coated over brackets in order to reduce bacterial aggregation and friction. However, their antimicrobial efficacy, surface roughness, and frictional resistance are not assessed before. Fifty-five stainless-steel brackets were divided into 5 groups of 11 brackets each: uncoated brackets, brackets coated with 60 µm silver, 100 µm silver, 60 µm titanium, and 100 µm titanium. Coating was performed using physical vapor deposition method. For friction test, three brackets from each group were randomly selected and tested. For scanning electron microscopy and atomic-force microscopy assessments, one and one brackets were selected from each group. For antibacterial assessment, six brackets were selected from each group. Of them, three were immediately subjected to direct contact with S. mutans. Colonies were counted 3, 6, 24, and 48 h of contact. The other three were stored in water for 3 months. Then were subjected to a similar direct contact test. Results pertaining to both subgroups were combined. Groups were compared statistically. Mean (SD) friction values of the groups 'control, silver-60, silver-100, titanium-60, and titanium-100' were 0.55 ± 0.14, 0.77 ± 0.08, 0.82 ± 0.11, 1.52 ± 0.24, and 1.57 ± 0.41 N, respectively (p = .0004, Kruskal-Wallis). Titanium frictions were significantly greater than control (p  .05, Dunn). In the uncoated group, colony count increased exponentially within 48 h. The coated groups showed significant reductions in colony count (p < .05, two-way-repeated-measures ANOVA). In conclusions, all four explained coatings reduce surface roughness and bacterial growth. Nano-titanium films are not suitable for friction reduction. Nano-silver results were not conclusive and need future larger studies. © 2016 Wiley Periodicals, Inc.

Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires

Science.gov (United States)

Asiry, Moshabab A.; AlShahrani, Ibrahim; Almoammar, Salem; Durgesh, Bangalore H.; Kheraif, Abdulaziz A. Al; Hashem, Mohamed I.

2018-02-01

Aim. To investigate the effect of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires Methods. Three different coated (Epoxy, polytetrafluoroethylene (PTFE) and rhodium) and one uncoated Ni-Ti archwires were evaluated in the present study. Surface roughness (Ra) was assessed using a non-contact surface profilometer. The mechanical properties (nano-hardness and elastic modulus) were measured using a nanoindenter. Bacterial adhesion assays were performed using Streptococcus mutans (MS) and streptococcus sobrinus (SS) in an in-vitro set up. The data obtained were analyzed using analyses of variance, Tukey’s post hoc test and Pearson’s correlation coefficient test. Result. The highest Ra values (1.29 ± 0.49) were obtained for epoxy coated wires and lowest Ra values (0.29 ± 0.16) were obtained for the uncoated wires. No significant differences in the Ra values were observed between the rhodium coated and uncoated archwires (P > 0.05). The highest nano-hardness (3.72 ± 0.24) and elastic modulus values (61.15 ± 2.59) were obtained for uncoated archwires and the lowest nano-hardness (0.18 ± 0.10) and elastic modulus values (4.84 ± 0.65) were observed for epoxy coated archwires. No significant differences in nano-hardness and elastic modulus values were observed between the coated archwires (P > 0.05). The adhesion of Streptococcus mutans (MS) to the wires was significantly greater than that of streptococcus sobrinus (SS). The epoxy coated wires demonstrated an increased adhesion of MS and SS and the uncoated wires demonstrated decreased biofilm adhesion. The Spearman correlation test showed that MS and SS adhesion was positively correlated with the surface roughness of the wires. Conclusion. The different surface coatings significantly influence the roughness, nano-mechanical properties and biofilm adhesion parameters of the archwires. The

Effect of ion-implantation on surface characteristics of nickel titanium and titanium molybdenum alloy arch wires

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Manu Krishnan

2013-01-01

Full Text Available Aim: To evaluate the changes in surface roughness and frictional features of ′ion-implanted nickel titanium (NiTi and titanium molybdenum alloy (TMA arch wires′ from its conventional types in an in-vitro laboratory set up. Materials and Methods: ′Ion-implanted NiTi and low friction TMA arch wires′ were assessed for surface roughness with scanning electron microscopy (SEM and 3 dimensional (3D optical profilometry. Frictional forces were studied in a universal testing machine. Surface roughness of arch wires were determined as Root Mean Square (RMS values in nanometers and Frictional Forces (FF in grams. Statistical Analysis Used: Mean values of RMS and FF were compared by Student′s ′t′ test and one way analysis of variance (ANOVA. Results: SEM images showed a smooth topography for ion-implanted versions. 3D optical profilometry demonstrated reduction of RMS values by 58.43% for ion-implanted NiTi (795.95 to 330.87 nm and 48.90% for TMA groups (463.28 to 236.35 nm from controls. Nonetheless, the corresponding decrease in FF was only 29.18% for NiTi and 22.04% for TMA, suggesting partial correction of surface roughness and disproportionate reduction in frictional forces with ion-implantation. Though the reductions were highly significant at P < 0.001, relations between surface roughness and frictional forces remained non conclusive even after ion-implantation. Conclusion: The study proved that ion-implantation can significantly reduce the surface roughness of NiTi and TMA wires but could not make a similar reduction in frictional forces. This can be attributed to the inherent differences in stiffness and surface reactivity of NiTi and TMA wires when used in combination with stainless steel brackets, which needs further investigations.

Creating nanoshell on the surface of titanium hydride bead

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PAVLENKO Vyacheslav Ivanovich

2016-12-01

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

Monitoring tablet surface roughness during the film coating process

DEFF Research Database (Denmark)

Seitavuopio, Paulus; Heinämäki, Jyrki; Rantanen, Jukka

2006-01-01

The purpose of this study was to evaluate the change of surface roughness and the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging, and energy dispersive X-ray (EDX) analysis. Surface roughness and texture changes developing during...... the process of film coating tablets were studied by noncontact laser profilometry and scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate and titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose, and the film...... coating was performed using an instrumented pilot-scale side-vented drum coater. The SEM images of the film-coated tablets showed that within the first 30 minutes, the surface of the tablet cores was completely covered with a thin film. The magnesium signal that was monitored by SEM-EDX disappeared after...

Evaluation of the safety and efficiency of novel metallic ultrasonic scaler tip on titanium surfaces.

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Baek, Seung-Ho; Shon, Won-Jun; Bae, Kwang-Shik; Kum, Kee-Yeon; Lee, Woo-Cheol; Park, Young-Seok

2012-11-01

To evaluate the safety and efficiency of novel ultrasonic scaler tips, conventional stainless-steel tips, and plastic tips on titanium surfaces. Mechanical instrumentation was carried out using conventional ultrasonic scalers (EMS, Nyon, Switzerland) with novel metallic implant tip (BS), a plastic-headed tip (ES), a plastic tip (PS) and a conventional stainless-steel tip (CS) on 10 polished commercially pure titanium disks (Grade II) per group. Arithmetic mean roughness (R(a) ) and maximum height roughness (R(y) ) of titanium samples were measured and dissipated power of the scaler tip in the tip-surface junction was estimated to investigate the scaling efficiency. The instrumented surface morphology of samples was viewed with a scanning electron microscope (SEM) and surface profile of the each sample was investigated using contact mode with a commercial atomic force microscope (AFM). There were no significant differences in surface roughness (R(a) and R(y) ) among BS, ES, and PS group. However, CS group showed significant higher surface roughness (R(a) and R(y) ). The efficiency of CS tip is twice as much higher than that of BS tip, the efficiency of BS tip is 20 times higher than that of PS tip, and the efficiency of BS tip is 90 times higher than that of ES tip. Novel metallic copper alloy ultrasonic scaler tips may minimally influence the titanium surface, similar to plastic tip. Therefore, they can be a suitable instrument for implant maintenance therapy. © 2011 John Wiley & Sons A/S.

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

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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.

Antibacterial effect of hydrogen peroxide-titanium dioxide suspensions in the decontamination of rough titanium surfaces.

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Wiedmer, David; Petersen, Fernanda Cristina; Lönn-Stensrud, Jessica; Tiainen, Hanna

2017-07-01

The chemical decontamination of infected dental implants is essential for the successful treatment of peri-implantitis. The aim of this study was to assess the antibacterial effect of a hydrogen peroxide-titanium dioxide (H 2 O 2 -TiO 2 ) suspension against Staphylococcus epidermidis biofilms. Titanium (Ti) coins were inoculated with a bioluminescent S. epidermidis strain for 8 h and subsequently exposed to H 2 O 2 with and without TiO 2 nanoparticles or chlorhexidine (CHX). Bacterial regrowth, bacterial load and viability after decontamination were analyzed by continuous luminescence monitoring, live/dead staining and scanning electron microscopy. Bacterial regrowth was delayed on surfaces treated with H 2 O 2 -TiO 2 compared to H 2 O 2 . H 2 O 2 -based treatments resulted in a lower bacterial load compared to CHX. Few viable bacteria were found on surfaces treated with H 2 O 2 and H 2 O 2 -TiO 2 , which contrasted with a uniform layer of dead bacteria for surfaces treated with CHX. H 2 O 2 -TiO 2 suspensions could therefore be considered an alternative approach in the decontamination of dental implants.

Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

International Nuclear Information System (INIS)

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

2012-01-01

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

Effects of titanium surface topography on morphology and in vitro activity of human gingival fibroblasts.

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Ramaglia, L; Capece, G; Di Spigna, G; Bruno, M P; Buonocore, N; Postiglione, L

2013-01-01

The aim of the present study was to evaluate in vitro the biological behavior of human gingival fibroblasts cultured on two different titanium surfaces. Titanium test disks were prepared with a machined, relatively smooth (S) surface or a rough surface (O) obtained by a double acid etching procedure. Primary cultures of human gingival fibroblasts were plated on the experimental titanium disks and cultured up to 14 days. Titanium disk surfaces were analysed by scanning electron microscopy (SEM). Cell proliferation and a quantitative analysis by ELISA in situ of ECM components as CoI, FN and TN were performed. Results have shown different effects of titanium surface microtopography on cell expression and differentiation. At 96 hours of culture on experimental surfaces human gingival fibroblasts displayed a favourable cell attachment and proliferation on both surfaces although showing some differences. Both the relatively smooth and the etched surfaces interacted actively with in vitro cultures of human gingival fibroblasts, promoting cell proliferation and differentiation. Results suggested that the microtopography of a double acid-etched rough surface may induce a greater Co I and FN production, thus conditioning in vivo the biological behaviour of human gingival fibroblasts during the process of peri-implant soft tissue healing.

Evidence of antibacterial activity on titanium surfaces through nanotextures

Energy Technology Data Exchange (ETDEWEB)

Seddiki, O.; Harnagea, C. [INRS – Centre Énergie, Matériaux et Télécommunications, Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Levesque, L.; Mantovani, D. [Laboratory for Biomaterials and Bioengineering (CRC-I), Dept Min-Met-Materials Engineering and Research Center CHU-Quebec, Laval University, Quebec City (Canada); Rosei, F., E-mail: rosei@emt.inrs.ca [INRS – Centre Énergie, Matériaux et Télécommunications, Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Center for Self-Assembled Chemical Structures, McGill University, H3A 2K6 Montreal, Quebec (Canada)

2014-07-01

Nosocomial infections (Nis) are a major concern for public health. As more and more of the pathogens responsible for these infections are antibiotic resistant, finding new ways to overcome them is a major challenge for biomedical research. We present a method to reduce Nis spreading by hindering bacterial adhesion in its very early stage. This is achieved by reducing the contact interface area between the bacterium and the surface by nanoengineering the surface topography. In particular, we studied the Escheria Coli adhesion on titanium surfaces exhibiting different morphologies, that were obtained by a combination of mechanical polishing and chemical etching. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) characterization revealed that the titanium surface is modified at both micro- and nano-scale. X-ray Photoelectron Spectroscopy (XPS) revealed that the surfaces have the same composition before and after piranha treatment, consisting mainly of TiO{sub 2}. Adhesion tests showed a significant reduction in bacterial accumulation on nanostructured surfaces that had the lowest roughness over large areas. SEM images acquired after bacterial culture on different titanium substrates confirmed that the polished titanium surface treated one hour in a piranha solution at a temperature of 25 °C has the lowest bacterial accumulation among all the surfaces tested. This suggests that the difference observed in bacterial adhesion between the different surfaces is due primarily to surface topography.

Evidence of antibacterial activity on titanium surfaces through nanotextures

International Nuclear Information System (INIS)

Seddiki, O.; Harnagea, C.; Levesque, L.; Mantovani, D.; Rosei, F.

2014-01-01

Nosocomial infections (Nis) are a major concern for public health. As more and more of the pathogens responsible for these infections are antibiotic resistant, finding new ways to overcome them is a major challenge for biomedical research. We present a method to reduce Nis spreading by hindering bacterial adhesion in its very early stage. This is achieved by reducing the contact interface area between the bacterium and the surface by nanoengineering the surface topography. In particular, we studied the Escheria Coli adhesion on titanium surfaces exhibiting different morphologies, that were obtained by a combination of mechanical polishing and chemical etching. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) characterization revealed that the titanium surface is modified at both micro- and nano-scale. X-ray Photoelectron Spectroscopy (XPS) revealed that the surfaces have the same composition before and after piranha treatment, consisting mainly of TiO 2 . Adhesion tests showed a significant reduction in bacterial accumulation on nanostructured surfaces that had the lowest roughness over large areas. SEM images acquired after bacterial culture on different titanium substrates confirmed that the polished titanium surface treated one hour in a piranha solution at a temperature of 25 °C has the lowest bacterial accumulation among all the surfaces tested. This suggests that the difference observed in bacterial adhesion between the different surfaces is due primarily to surface topography.

Evaluation of Antibacterial Activity of Titanium Surface Modified by PVD/PACVD Process.

Science.gov (United States)

Ji, Min-Kyung; Lee, Min-Joo; Park, Sang-Won; Lee, Kwangmin; Yun, Kwi-Dug; Kim, Hyun-Seung; Oh, Gye-Jeong; Kim, Ji-Hyun; Lim, Hyun-Pil

2016-02-01

The aim of this study was to evaluate the response of Streptococcus mutans (S. mutans) via crystal violet staining assay on titanium surface modified by physical vapor deposition/plasma assisted chemical vapor deposition process. Specimens were divided into the following three groups: polished titanium (control group), titanium modified by DC magnetron sputtering (group TiN-Ti), and titanium modified by plasma nitriding (group N-Ti). Surface characteristics of specimens were observed by using nanosurface 3D optical profiler and field emission scanning electron microscope. Group TiN-Ti showed TiN layer of 1.2 microm in thickness. Group N-Ti was identified as plasma nitriding with X-ray photoelectron spectroscopy. Roughness average (Ra) of all specimens had values 0.05). Within the process condition of this study, modified titanium surfaces by DC magnetron sputtering and plasma nitriding did not influence the adhesion of S. mutans.

An In Vitro Evaluation of Alumina, Zirconia, and Lithium Disilicate Surface Roughness Caused by Two Scaling Instruments.

Science.gov (United States)

Vigolo, Paolo; Buzzo, Ottavia; Buzzo, Maurizio; Mutinelli, Sabrina

2017-02-01

Plaque control is crucial for the prevention of inflammatory periodontal disease. Hand scaling instruments have been shown to be efficient for the removal of plaque; however, routine periodontal prophylactic procedures may modify the surface profile of restorative materials. The purpose of this study was to assess in vitro the changes in roughness of alumina, zirconia, and lithium disilicate surfaces treated by two hand scaling instruments. Forty-eight alumina specimens, 48 zirconia specimens, and 48 lithium disilicate specimens, were selected. All specimens were divided into three groups of 16 each; one group for each material was considered the control group and no scaling procedures were performed; the second group of each material was exposed to scaling with steel curettes simulating standard clinical conditions; the third group of each material was exposed to scaling with titanium curettes. After scaling, the surface roughness of the specimens was evaluated with a profilometer. First, a statistical test was carried out to evaluate the difference in surface roughness before the scaling procedure of the three materials was effected (Kruskal-Wallis test). Subsequently, the effect of curette material (steel and titanium) on roughness difference and roughness ratio was analyzed throughout the entire sample and within each material group, and a nonparametric test for dependent values was conducted (Wilcoxon signed-rank test). Finally, the roughness ratios of the three material groups were compared by means of a Kruskal-Wallis test and a Wilcoxon signed-rank test. Upon completion of profilometric evaluation, representative specimens from each group were prepared for SEM evaluation to evaluate the effects of the two scaling systems on the different surfaces qualitatively. After scaling procedure, the roughness profile value increased in all disks. Classifying the full sample according to curette used, the roughness of the disks treated with a steel curette reached a

Electrochemical surface modification of titanium in dentistry.

Science.gov (United States)

Kim, Kyo-Han; Ramaswamy, Narayanan

2009-01-01

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

Plasma Electrolytic Oxidation of Titanium Implant Surfaces: Microgroove-Structures Improve Cellular Adhesion and Viability.

Science.gov (United States)

Hartjen, Philip; Hoffmann, Alexia; Henningsen, Anders; Barbeck, Mike; Kopp, Alexander; Kluwe, Lan; Precht, Clarissa; Quatela, Olivia; Gaudin, Robert; Heiland, Max; Friedrich, Reinhard E; Knipfer, Christian; Grubeanu, Daniel; Smeets, Ralf; Jung, Ole

2018-01-01

Plasma electrolytic oxidation (PEO) is an established electrochemical treatment technique that can be used for surface modifications of metal implants. In this study we to treated titanium implants with PEO, to examine the resulting microstructure and to characterize adhesion and viability of cells on the treated surfaces. Our aim was to identify an optimal surface-modification for titanium implants in order to improve soft-tissue integration. Three surface-variants were generated on titanium alloy Ti6Al4V by PEO-treatment. The elemental composition and the microstructures of the surfaces were characterized using energy dispersive X-ray spectroscopy, scanning electron microscopy and profilometry. In vitro cytocompatibility of the surfaces was assessed by seeding L929 fibroblasts onto them and measuring the adhesion, viability and cytotoxicity of cells by means of live/dead staining, XTT assay and LDH assay. Electron microscopy and profilometry revealed that the PEO-surface variants differed largely in microstructure/topography, porosity and roughness from the untreated control material as well as from one another. Roughness was generally increased after PEO-treatment. In vitro, PEO-treatment led to improved cellular adhesion and viability of cells accompanied by decreased cytotoxicity. PEO-treatment provides a promising strategy to improve the integration of titanium implants with surrounding tissues. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Surface excitation parameter for rough surfaces

International Nuclear Information System (INIS)

Da, Bo; Salma, Khanam; Ji, Hui; Mao, Shifeng; Zhang, Guanghui; Wang, Xiaoping; Ding, Zejun

2015-01-01

Graphical abstract: - Highlights: • Instead of providing a general mathematical model of roughness, we directly use a finite element triangle mesh method to build a fully 3D rough surface from the practical sample. • The surface plasmon excitation can be introduced to the realistic sample surface by dielectric response theory and finite element method. • We found that SEP calculated based on ideal plane surface model are still reliable for real sample surface with common roughness. - Abstract: In order to assess quantitatively the importance of surface excitation effect in surface electron spectroscopy measurement, surface excitation parameter (SEP) has been introduced to describe the surface excitation probability as an average number of surface excitations that electrons can undergo when they move through solid surface either in incoming or outgoing directions. Meanwhile, surface roughness is an inevitable issue in experiments particularly when the sample surface is cleaned with ion beam bombardment. Surface roughness alters not only the electron elastic peak intensity but also the surface excitation intensity. However, almost all of the popular theoretical models for determining SEP are based on ideal plane surface approximation. In order to figure out whether this approximation is efficient or not for SEP calculation and the scope of this assumption, we proposed a new way to determine the SEP for a rough surface by a Monte Carlo simulation of electron scattering process near to a realistic rough surface, which is modeled by a finite element analysis method according to AFM image. The elastic peak intensity is calculated for different electron incident and emission angles. Assuming surface excitations obey the Poisson distribution the SEPs corrected for surface roughness are then obtained by analyzing the elastic peak intensity for several materials and for different incident and emission angles. It is found that the surface roughness only plays an

Nanocoating of titanium implant surfaces with organic molecules. Polysaccharides including glycosaminoglycans

DEFF Research Database (Denmark)

Gurzawska, Katarzyna Aleksandra; Svava, Rikke; Jørgensen, Niklas Rye

2012-01-01

Long-term stability of titanium implants are dependent on a variety of factors. Nanocoating with organic molecules is one of the method used to improve osseointegration. Nanoscale modification of titanium implants affects surface properties, such as hydrophilicity, biochemical bonding capacity...... and roughness. This influences cell behaviour on the surface such as adhesion, proliferation and differentiation of cells as well as the mineralization of the extracellular matrix at the implant surfaces. The aim of the present systematic review was to describe organic molecules used for surface nanocoating...... nanocoatings. The included in vivo studies, showed improvement of bone interface reactions measured as increased Bone-to-Implant Contact length and Bone Mineral Density adjacent to the polysaccharide coated surfaces. Based on existing literature, surface modification with polysaccharide and glycosaminoglycans...

Effects of intraoral aging on surface properties of coated nickel-titanium archwires.

Science.gov (United States)

Rongo, Roberto; Ametrano, Gianluca; Gloria, Antonio; Spagnuolo, Gianrico; Galeotti, Angela; Paduano, Sergio; Valletta, Rosa; D'Antò, Vincenzo

2014-07-01

To evaluate the effects of intraoral aging on surface properties of esthetic and conventional nickel-titanium (NiTi) archwires. Five NiTi wires were considered for this study (Sentalloy, Sentalloy High Aesthetic, Superelastic Titanium Memory Wire, Esthetic Superelastic Titanium Memory Wire, and EverWhite). For each type of wire, four samples were analyzed as received and after 1 month of clinical use by an atomic force microscope (AFM) and a scanning electronic microscope (SEM). To evaluate sliding resistance, two stainless steel plates with three metallic or three monocrystalline brackets, bonded in passive configuration, were manufactured; four as-received and retrieved samples for every wire were pulled five times at 5 mm/min for 1 minute by means of an Instron 5566, recording the greatest friction value (N). Data were analyzed by one-way analysis of variance and by Student's t-test. After clinical use, surface roughness increased considerably. The SEM images showed homogeneity for the as-received control wires; however, after clinical use esthetic wires exhibited a heterogeneous surface with craters and bumps. The lowest levels of friction were observed with the as-received Superelastic Titanium Memory Wire on metallic brackets. When tested on ceramic brackets, all the wires exhibited an increase in friction (t-test; P Sentalloy, showed a statistically significant increase in friction between the as-received and retrieved groups (t-test; P < .05). Clinical use of the orthodontic wires increases their surface roughness and the level of friction.

The maintenance of inserted titanium implants: in-vitro evaluation of exposed surfaces cleaned with three different instruments.

Science.gov (United States)

Bertoldi, Carlo; Lusuardi, Donatella; Battarra, Francesca; Sassatelli, Paolo; Spinato, Sergio; Zaffe, Davide

2017-01-01

Changes to titanium implants smooth-surfaces after instrumentation were comparatively analyzed using low-vacuum scanning electron microscopy (LV-SEM) and white-light confocal (WLC) profilometry, to accurately evaluate curved surfaces. Sixty titanium implants screwed to their abutments were randomly split into three groups for cleaning treatment with (S) stainless-steel Gracey-curettes, (T) titanium Langer-curettes, and (P) an ultrasonic-device with the probe covered with a plastic-tip. One sector of each implant was left unprocessed (U). The other sectors were cleaned for either 60 s, to simulate a single cleaning session, or 180 s to simulate a series of sessions. Surface morphology was analyzed by LV-SEM, without metal sputtering. Quantitative evaluations of the roughness of surfaces were performed using a WLC-profilometer. The Wilcoxon and the Mann-Whitney tests were used in statistical comparisons. U-surfaces showed that thin transverse ridges and grooves, i.e. a polarized surface roughness was substantially compromised after S-instrumentation. Small surface alterations, increasing with time, were also recorded after T-·and·P-instrumentation, although to a lesser degree. The gap of the fixture-abutment connection appeared almost completely clean after T-, clotted with titanium debris after S-, and clotted with plastic debris after P-treatment. The mean roughness (Ra) was unchanged after P-, significantly increased after S- and decreased after T-treatment, when compared with U. The Rz roughness-parameter, calculated along the fixture Y-axis, of S, T, and P resulted similar and significantly lower than that of U. Rz (X-axis) resulted unchanged after P-, slightly increased (+40%) after T-, and greatly increased (+260%) after S-treatment, this latter being statistically significant when compared with U. The careful use of titanium-curettes could produce only minimal smooth surface alteration particularly over prolonged treatments, and avoid debris production

Electrochemical and morphological analyses on the titanium surface modified by shot blasting and anodic oxidation processes

Energy Technology Data Exchange (ETDEWEB)

Szesz, Eduardo M., E-mail: eszesz@neoortho.com.br [Neoortho Research Institute, Rua Ângelo Domingos Durigan, 607-Cascatinha, CEP 82025-100 Curitiba, PR (Brazil); Pereira, Bruno L., E-mail: brnl7@hotmail.com [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Kuromoto, Neide K., E-mail: kuromoto@fisica.ufpr.br [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Marino, Claudia E.B., E-mail: claudiamarino@yahoo.com [Mechanical Engineering Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Souza, Gelson B. de, E-mail: gelsonbs@uepg.br [Physics Department, Universidade Estadual de Ponta Grossa, 84051-510 Ponta Grossa, PR (Brazil); Soares, Paulo, E-mail: pa.soares@pucpr.br [Mechanical Engineering Department, Pontifícia Universidade Católica do Paraná, 80215-901 Curitiba, PR (Brazil)

2013-01-01

In recent years, many surface modification processes have been developed in order to induce the osseointegration on titanium surface and thus to improve the implants' biocompatibility. In this work, Ti surface has been modified by shot blasting followed by anodic oxidation process in order to associate the good surface characteristics of both processes to obtain a rough and porous surface able to promote the titanium surface bioactivity. Commercially pure titanium (grade 2) plates were used on the surface treatments that were as follows: Shot blasting (SB) performed using alumina (Al{sub 2}O{sub 3}) particles, and anodic oxidation (AO) using NaOH electrolyte. The morphology, structural changes and the open-circuit potentials (OCP) of the surfaces were analyzed. It can be observed that an increase on the roughness of the blasted surface and a rough and porous surface happens after the AO process. The anodic film produced is thin and followed the blasted surface topography. It can be observed that there are small pores with regular shape covering the entire surface. X-ray diffraction results showed the presence of the anatase and rutile phases on the blasted and anodized surface after heat treatment at 600 °C/1 h. Concerning electrochemical measurements, when the different samples were submitted to open-circuit conditions in a physiological electrolyte, the protective effect increases with the oxidation process due to the oxide layer. When the surface was blasted, the OCP was more negative when compared with the Ti surface without surface treatments. - Highlights: ► A combination of shot blasting and anodic oxidation surface treatments is proposed. ► Both processes produced an increase in roughness compared to the polished surface. ► The combination of processes produced a rough and porous surface. ► Open circuit results show that the protective effect increases with oxidation process. ► The combination of processes presents the better results in this

Surface analysis of titanium dental implants with different topographies

Directory of Open Access Journals (Sweden)

Silva M.H. Prado da

2000-01-01

Full Text Available Cylindrical dental implants made of commercially pure titanium were analysed in four different surface finishes: as-machined, Al2O3 blasted with Al2O3 particles, plasma-sprayed with titanium beads and electrolytically coated with hydroxyapatite. Scanning electron microscopy (SEM with Energy Dispersive X-ray Analysis (EDX revealed the topography of the surfaces and provided qualitative results of the chemical composition of the different implants. X-ray Photoelectron Spectroscopy (XPS was used to perform chemical analysis on the surface of the implants while Laser Scanning Confocal Microscopy (LSM produced topographic maps of the analysed surfaces. Optical Profilometry was used to quantitatively characterise the level of roughness of the surfaces. The implant that was plasma-sprayed and the hydroxyapatite coated implant showed the roughest surface, followed by the implant blasted with alumina and the as-machined implant. Some remnant contamination from the processes of blasting, coating and cleaning was detected by XPS.

The Influence of Surface Roughness on Biocompatibility and Fatigue Life of Titanium Based Alloys

Science.gov (United States)

Major, S.; Cyrus, P.; Hubálovská, M.

2017-02-01

This article deals with the effect of treatment on the mechanical properties ofbiocompatible alloys. In the case of implants, it is desirable to ensure good biocompatibility. Generally, the environment in the body is very aggressive and implants can quickly degrade due the corrosion. The process of corrosion leads to the release of harmful particles into the body. Other reasons for rejection of the implants, is their coverage bacterial plaque. Another reason for the rejection of the implant may be a smooth surface. In some cases, the tissue does not adhere to the smooth surface of the implant, in this regionsoccurs an accumulation of body fluids. This problem can be solved with a rough surface. From the viewpoint of fatigue resistance, the rough surface containing grooves and holes has a negative influence on the fatigue resistance against mechanical loading. The rough surface can be produced by machining or asymmetric deposition of particles of oxides, nitrides or other particles on surface. In this work the formation and propagation of fatigue cracks in the material with granular surface is analysed. The formation and growth of fatigue crack originated from granular surface is simulated. Also, experimental studies were carried out.

Surface treatment of a titanium implant using low temperature atmospheric pressure plasmas

Science.gov (United States)

Lee, Hyun-Young; Tang, Tianyu; Ok, Jung-Woo; Kim, Dong-Hyun; Lee, Ho-Jun; Lee, Hae June

2015-09-01

During the last two decades, atmospheric pressure plasmas(APP) are widely used in diverse fields of biomedical applications, reduction of pollutants, and surface treatment of materials. Applications of APP to titanium surface of dental implants is steadily increasing as it renders surfaces wettability and modifies the oxide layer of titanium that hinders the interaction with cells and proteins. In this study, we have treated the titanium surfaces of screw-shaped implant samples using a plasma jet which is composed of a ceramic coaxial tube of dielectrics, a stainless steel inner electrode, and a coper tube outer electrode. The plasma ignition occurred with Ar gas flow between two coaxial metal electrodes and a sinusoidal bias voltage of 3 kV with a frequency of 20 kHz. Titanium materials used in this study are screw-shaped implants of which diameter and length are 5 mm and 13 mm, respectively. Samples were mounted at a distance of 5 mm below the plasma source, and the plasma treatment time was set to 3 min. The wettability of titanium surface was measured by the moving speed of water on its surface, which is enhanced by plasma treatment. The surface roughness was also measured by atomic force microscopy. The optimal condition for wettability change is discussed.

In vitro cytotoxicity and surface topography evaluation of additive manufacturing titanium implant materials.

Science.gov (United States)

Tuomi, Jukka T; Björkstrand, Roy V; Pernu, Mikael L; Salmi, Mika V J; Huotilainen, Eero I; Wolff, Jan E H; Vallittu, Pekka K; Mäkitie, Antti A

2017-03-01

Custom-designed patient-specific implants and reconstruction plates are to date commonly manufactured using two different additive manufacturing (AM) technologies: direct metal laser sintering (DMLS) and electron beam melting (EBM). The purpose of this investigation was to characterize the surface structure and to assess the cytotoxicity of titanium alloys processed using DMLS and EBM technologies as the existing information on these issues is scarce. "Processed" and "polished" DMLS and EBM disks were assessed. Microscopic examination revealed titanium alloy particles and surface flaws on the processed materials. These surface flaws were subsequently removed by polishing. Surface roughness of EBM processed titanium was higher than that of DMLS processed. The cytotoxicity results of the DMLS and EBM discs were compared with a "gold standard" commercially available titanium mandible reconstruction plate. The mean cell viability for all discs was 82.6% (range, 77.4 to 89.7) and 83.3% for the control reconstruction plate. The DMLS and EBM manufactured titanium plates were non-cytotoxic both in "processed" and in "polished" forms.

Effect of applied voltage on surface properties of anodised titanium in mixture of β-glycerophosphate (β-GP) and calcium acetate (CA)

Energy Technology Data Exchange (ETDEWEB)

Chuan, Lee Te, E-mail: gd130079@siswa.uthm.edu.my; Rathi, Muhammad Fareez Mohamad, E-mail: cd110238@siswa.uthm.edu.my; Abidin, Muhamad Yusuf Zainal, E-mail: cd110221@siswa.uthm.edu.my; Abdullah, Hasan Zuhudi, E-mail: hasan@uthm.edu.my; Idris, Maizlinda Izwana, E-mail: izwana@uthm.edu.my [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor (Malaysia)

2015-07-22

Anodic oxidation is a surface modification method which combines electric field driven metal and oxygen ion diffusion for formation of oxide layer on the anode surface. This method has been widely used to modify the surface morphology of biomaterial especially titanium. This study aimed to investigate the effect of applied voltage on titanium. Specifically, the titanium foil was anodised in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) with different applied voltage (50-350 V), electrolyte concentration (0.04 M β-GP + 0.4 M CA), anodising time (10minutes) and current density (50 and 70 mA.cm{sup −2}) at room temperature. Surface oxide properties of anodised titanium were characterised by digital single-lens reflex camera (DSLR camera), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM). At lower applied voltage (≤150 V), surface of titanium foils were relatively smooth. With increasing applied voltage (≥250 V), the oxide layer became more porous and donut-shaped pores were formed on the surface of titanium foils. The AFM results indicated that the surface roughness of anodised titanium increases with increasing of applied voltage. The porous and rough surface is able to promote the osseointegration and reduce the suffering time of patient.

Application of Box-Behnken Design and Response Surface Methodology for Surface Roughness Prediction Model of CP-Ti Powder Metallurgy Components Through WEDM

Science.gov (United States)

Das, Arunangsu; Sarkar, Susenjit; Karanjai, Malobika; Sutradhar, Goutam

2018-04-01

The present work was undertaken to investigate and characterize the machining parameters (such as surface roughness, etc.) of uni-axially pressed commercially pure titanium sintered powder metallurgy components. Powder was uni-axially pressed at designated pressure of 840 MPa to form cylindrical samples and the green compacts were sintered at 0.001 mbar for about 4 h with sintering temperature varying from 1350 to 1450 °C. The influence of the sintering temperature, pulse-on and pulse-off time at wire-EDM on the surface roughness of the preforms has been investigated thoroughly. Experiments were conducted under different machining parameters in a CNC operated wire-cut EDM. The surface roughness of the machined surface was measured and critically analysed. The optimum surface roughness was achieved under the conditions of 6 μs pulse-on time, 9 μs pulse-off time and at sintering temperature of 1450 °C.

Application of Box-Behnken Design and Response Surface Methodology for Surface Roughness Prediction Model of CP-Ti Powder Metallurgy Components Through WEDM

Science.gov (United States)

Das, Arunangsu; Sarkar, Susenjit; Karanjai, Malobika; Sutradhar, Goutam

2017-06-01

The present work was undertaken to investigate and characterize the machining parameters (such as surface roughness, etc.) of uni-axially pressed commercially pure titanium sintered powder metallurgy components. Powder was uni-axially pressed at designated pressure of 840 MPa to form cylindrical samples and the green compacts were sintered at 0.001 mbar for about 4 h with sintering temperature varying from 1350 to 1450 °C. The influence of the sintering temperature, pulse-on and pulse-off time at wire-EDM on the surface roughness of the preforms has been investigated thoroughly. Experiments were conducted under different machining parameters in a CNC operated wire-cut EDM. The surface roughness of the machined surface was measured and critically analysed. The optimum surface roughness was achieved under the conditions of 6 μs pulse-on time, 9 μs pulse-off time and at sintering temperature of 1450 °C.

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

Science.gov (United States)

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

Pectin nanocoating of titanium implant surfaces - an experimental study in rabbits

DEFF Research Database (Denmark)

Gurzawska, Katarzyna Aleksandra; Dirscherl, Kai; Jørgensen, Bodil

2017-01-01

that may increase adhesion of bone proteins, and bone cells at the implant surface. Nanocoating with pectins, plant cell wall-derived polysaccharides, is frequently done using rhamnogalacturonan-I (RG-I). AIM: The aim of the study was to evaluate the effect of nanocoating titanium implants with plant cell...... wall-derived rhamnogalacturonan-I, on bone healing and osseointegration. MATERIAL AND METHODS: Machined titanium implants were coated with three modifications of rhamnogalacturonan-I (RG-I). Chemical and physical surface properties were examined before insertion of nanocoated implants (n = 96....... The bone response to the nanocoated implants was analyzed qualitatively and quantitatively after 2, 4, 6, and 8 weeks of healing using light microscopy and histomorphometric methods. RESULTS: The RG-I coating influenced the surface chemical composition; wettability and roughness, making the surface more...

Modified titanium surface with gelatin nano gold composite increases osteoblast cell biocompatibility

International Nuclear Information System (INIS)

Lee, Young-Hee; Bhattarai, Govinda; Aryal, Santosh; Lee, Nan-Hee; Lee, Min-Ho; Kim, Tae-Gun; Jhee, Eun-Chung; Kim, Hak-Yong; Yi, Ho-Keun

2010-01-01

This study examined the gelatin nano gold (GnG) composite for surface modification of titanium in addition to insure biocompatibility on dental implants or biomaterials. The GnG composite was constructed by gelatin and hydrogen tetrachloroaurate in presence of reducing agent, sodium borohydrate (NabH 4 ). The GnG composite was confirmed by UV-VIS spectroscopy and transmission electron microscopy (TEM). A dipping method was used to modify the titanium surface by GnG composite. Surface was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The MC-3T3 E1 cell viability was assessed by trypan blue and the expression of proteins to biocompatibility were analyzed by Western blotting. The GnG composite showed well dispersed character, the strong absorption at 530 nm, roughness, regular crystal and clear C, Na, Cl, P, and Au signals onto titanium. Further, this composite allowed MC-3T3 E1 growth and viability compared to gelatin and pure titanium. It induced ERK activation and the expression of cell adherent molecules, FAK and SPARC, and growth factor, VEGF. However, GnG decreased the level of SAPK/JNK. This shows that GnG composite coated titanium surfaces have a good biocompatibility for osteoblast growth and attachment than in intact by simple and versatile dipping method. Furthermore, it offers good communication between cell and implant surfaces by regulating cell signaling and adherent molecules, which are useful to enhance the biocompatibility of titanium surfaces.

Improvement of Surface Properties of CP-Titanium by Thermo-Chemical Treatment (TCT) Process

International Nuclear Information System (INIS)

Jeong, Hyeon-Gyeong; Hur, Bo-Young; Lee, Dong-Geun; Lee, Yong-Tai; Yaskiv, O.

2011-01-01

The thermo-chemical treatment (TCT) process was applied to achieve surface hardening of CP titanium. The following three different surface modification conditions were tested so that the best surface hardening process could be selected:(a) PVD, (b) TCT+PVD, and (c) TCT+Aging+PVD. These specimens were tested and analyzed in terms of surface roughness, wear, friction coefficient, and the gradient of hardening from the surface of the matrix. The three test conditions were all beneficial to improve the surface hardness of CP titanium. Moreover, the TCT treated specimens, that is, (b) and (c), showed significantly improved surface hardness and low friction coefficients through the thickness up to 100um. This is due to the functionally gradient hardened surface improvement by the diffused interstitial elements. The hardened surface also showed improvement in bonding between the PVD and TCT surface, and this leads to improvement in wear resistance. However, TCT after aging treatment did not show much improvement in surface properties compared to TCT only. For the best surface hardening on CP titanium, TCT+PVD has advantages in surface durability and economics.

Does surface anodisation of titanium implants change osseointegration and make their extraction from bone any easier?

Science.gov (United States)

Langhoff, J D; Mayer, J; Faber, L; Kaestner, S B; Guibert, G; Zlinszky, K; Auer, J A; von Rechenberg, B

2008-01-01

Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. The new surfaces were referenced to a stainless steel implant and a standard titanium implant surface (TiMAX). In a sheep limb model, healing period was 3 months. Bone-implant bonding was evaluated either biomechanically or histologically. The new surface anodized screws demonstrated similar or slightly higher bone-implant-contact (BIC) and torque release forces than the titanium reference. The BIC of the stainless steel implants was significant lower than two of the anodized surfaces (p = 0.04), but differences between stainless steel and all titanium implants in torque release forces were not significant (p = 0.06). The new anodized titanium surfaces showed good bone-implant bonding despite a smooth surface and increased nanohardness. However, they failed to facilitate implant removal at 3 months.

Does surface anodisation of titanium implants change osseointegration and make their extraction from bone any easier?

OpenAIRE

Langhoff, J; Mayer, J; Faber, L; Kästner, S B; Guibert, G; Zlinszky, K; Auer, J A; von Rechenberg, B

2008-01-01

Objectives: Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. Material and methods...

Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy.

Science.gov (United States)

Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra

2017-01-01

Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1min) caused decrease in the surface hydrophilic character, while longer time (10min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of storage methods on time-related changes of titanium surface properties and cellular response

International Nuclear Information System (INIS)

Lu Haibin; Zhou Lei; Wan Lei; Li Shaobing; Rong Mingdeng; Guo Zehong

2012-01-01

Titanium implants are sold in the market as storable medical devices. All the implants have a certain shelf life during which they maintain their sterility, but variations of the surface properties through this duration have not been subject to a comprehensive assessment. The aim of this study was to investigate the effects of storage methods on time-related changes of titanium surface properties. Acid-etched titanium discs (Sa = 0.82 µm) were placed in a sealed container (tradition method) or submerged in the ddH 2 O/NaCl solution (0.15 mol L −1 )/CaCl 2 solution (0.15 mol L −1 ), and new titanium discs were used as a control group. SEM and optical profiler showed that surface morphology and roughness did not change within different groups, but the XPS analysis confirmed that the surface chemistry altered by different storage protocols as the storage duration increased, and the contact angle also varied with storage methods. The storage method also affected the protein adsorption capacity and cellular response on the titanium surface. All titanium discs stored in the solution maintained their excellent bioactivity even after four weeks storage time, but titanium discs stored in a traditional manner decreased substantially in an age-dependent manner. Much effort is needed to improve the storage methods in order to maintain the bioactivity of a titanium dental implant. (paper)

Surface Corrosion Resistance in Turning of Titanium Alloy

Directory of Open Access Journals (Sweden)

Rui Zhang

2015-01-01

Full Text Available This work addresses the issues associated with implant surface modification. We propose a method to form the oxide film on implant surfaces by dry turning to generate heat and injecting oxygen-rich gas at the turning-tool flank. The morphology, roughness, composition, and thickness of the oxide films in an oxygen-rich atmosphere were characterized using scanning electron microscopy, optical profiling, and Auger electron spectroscopy. Electrochemical methods were used to study the corrosion resistance of the modified surfaces. The corrosion resistance trends, analyzed relative to the oxide film thickness, indicate that the oxide film thickness is the major factor affecting the corrosion resistance of titanium alloys in a simulated body fluid (SBF. Turning in an oxygen-rich atmosphere can form a thick oxide film on the implant surface. The thickness of surface oxide films processed at an oxygen concentration of 80% was improved to 4.6 times that of films processed at an oxygen concentration of 21%; the free corrosion potential shifted positively by 0.357 V, which significantly improved the corrosion resistance of titanium alloys in the SBF. Therefore, the proposed method may (partially replace the subsequent surface oxidation. This method is significant for biomedical development because it shortens the process flow, improves the efficiency, and lowers the cost.

Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy

Energy Technology Data Exchange (ETDEWEB)

Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl

2017-01-01

Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1 min) caused decrease in the surface hydrophilic character, while longer time (10 min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. - Highlights: • Surface of five Ti-6Al-4V alloy samples were smoothed and polished successively. • The

A quantitative AFM analysis of nano-scale surface roughness in various orthodontic brackets.

Science.gov (United States)

Lee, Gi-Ja; Park, Ki-Ho; Park, Young-Guk; Park, Hun-Kuk

2010-10-01

In orthodontics, the surface roughnesses of orthodontic archwire and brackets affect the effectiveness of arch-guided tooth movement, corrosion behavior, and the aesthetics of orthodontic components. Atomic force microscopy (AFM) measurements were used to provide quantitative information on the surface roughness of the orthodontic material. In this study, the changes in surface roughness of various orthodontic bracket slots before and after sliding movement of archwire in vitro and in vivo were observed through the utilization of AFM. Firstly, we characterized the surface of four types of brackets slots as follows: conventional stainless steel (Succes), conventional ceramic (Perfect), self-ligating stainless steel (Damon) and self-ligating ceramic (Clippy-C) brackets. Succes) and Damon brackets showed relatively smooth surfaces, while Perfect had the roughest surface among the four types of brackets used. Secondly, after in vitro sliding test with beta titanium wire in two conventional brackets (Succes and Perfect), there were significant increases in only stainless steel bracket, Succes. Thirdly, after clinical orthodontic treatment for a maximum of 2 years, the self-ligating stainless steel bracket, Damon, showed a significant increase in surface roughness. But self-ligating ceramic brackets, Clippy-C, represented less significant changes in roughness parameters than self-ligating stainless steel ones. Based on the results of the AFM measurements, it is suggested that the self-ligating ceramic bracket has great possibility to exhibit less friction and better biocompatibility than the other tested brackets. This implies that these bracket slots will aid in the effectiveness of arch-guided tooth movement.

Peen treatment on a titanium implant: effect of roughness, osteoblast cell functions, and bonding with bone cement

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Khandaker M

2016-02-01

Full Text Available Morshed Khandaker,1,4 Shahram Riahinezhad,1 Fariha Sultana,1 Melville B Vaughan,2,4 Joshua Knight,2 Tracy L Morris3,4 1Department of Engineering & Physics, 2Department of Biology, 3Department of Mathematics and Statistics, 4Center for Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK, USA Abstract: Implant failure due to poor integration of the implant with the surrounding biomaterial is a common problem in various orthopedic and orthodontic surgeries. Implant fixation mostly depends upon the implant surface topography. Micron to nanosize circular-shaped groove architecture with adequate surface roughness can enhance the mechanical interlock and osseointegration of an implant with the host tissue and solve its poor fixation problem. Such groove architecture can be created on a titanium (Ti alloy implant by laser peening treatment. Laser peening produces deep, residual compressive stresses in the surfaces of metal parts, delivering increased fatigue life and damage tolerance. The scientific novelty of this study is the controlled deposition of circular-shaped rough spot groove using laser peening technique and understanding the effect of the treatment techniques for improving the implant surface properties. The hypothesis of this study was that implant surface grooves created by controlled laser peen treatment can improve the mechanical and biological responses of the implant with the adjoining biomaterial. The objective of this study was to measure how the controlled laser-peened groove architecture on Ti influences its osteoblast cell functions and bonding strength with bone cement. This study determined the surface roughness and morphology of the peen-treated Ti. In addition, this study compared the osteoblast cell functions (adhesion, proliferation, and differentiation between control and peen-treated Ti samples. Finally, this study measured the fracture strength between each kind of Ti samples

Effect of calcium phosphate coating crystallinity and implant surface roughness on differentiation of rat bone marrow cells.

NARCIS (Netherlands)

Brugge, P.J. ter; Wolke, J.G.C.; Jansen, J.A.

2002-01-01

In this study, we examined the effect of calcium phosphate (Ca-P) coating crystallinity and of surface roughness on growth and differentiation of osteogenic cells. Grit-blasted titanium substrates were provided with Ca-P coatings of different crystallinities. Rat bone marrow (RBM) cells were

Nanoscale Electrical Potential and Roughness of a Calcium Phosphate Surface Promotes the Osteogenic Phenotype of Stromal Cells

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Igor A. Khlusov

2018-06-01

Full Text Available Mesenchymal stem cells (MSCs and osteoblasts respond to the surface electrical charge and topography of biomaterials. This work focuses on the connection between the roughness of calcium phosphate (CP surfaces and their electrical potential (EP at the micro- and nanoscales and the possible role of these parameters in jointly affecting human MSC osteogenic differentiation and maturation in vitro. A microarc CP coating was deposited on titanium substrates and characterized at the micro- and nanoscale. Human adult adipose-derived MSCs (hAMSCs or prenatal stromal cells from the human lung (HLPSCs were cultured on the CP surface to estimate MSC behavior. The roughness, nonuniform charge polarity, and EP of CP microarc coatings on a titanium substrate were shown to affect the osteogenic differentiation and maturation of hAMSCs and HLPSCs in vitro. The surface EP induced by the negative charge increased with increasing surface roughness at the microscale. The surface relief at the nanoscale had an impact on the sign of the EP. Negative electrical charges were mainly located within the micro- and nanosockets of the coating surface, whereas positive charges were detected predominantly at the nanorelief peaks. HLPSCs located in the sockets of the CP surface expressed the osteoblastic markers osteocalcin and alkaline phosphatase. The CP multilevel topography induced charge polarity and an EP and overall promoted the osteoblast phenotype of HLPSCs. The negative sign of the EP and its magnitude at the micro- and nanosockets might be sensitive factors that can trigger osteoblastic differentiation and maturation of human stromal cells.

Titanium surface topography after brushing with fluoride and fluoride-free toothpaste simulating 10 years of use.

Science.gov (United States)

Fais, Laiza M G; Fernandes-Filho, Romeu B; Pereira-da-Silva, Marcelo A; Vaz, Luis G; Adabo, Gelson L

2012-04-01

To conduct a controlled study contrasting titanium surface topography after procedures that simulated 10 years of brushing using toothpastes with or without fluoride. Commercially pure titanium (cp Ti) and Ti-6Al-4V disks (6 mm Ø×4 mm) were mirror-polished and treated according to 6 groups (n=6) as a function of immersion (I) or brushing (B) using deionised water (W), fluoride-free toothpaste (T) and fluoride toothpaste (FT). Surface topography was evaluated at baseline (pretreatment) and post-treatment, using atomic force microscope in order to obtain three-dimensional images and mean roughness. Specimens submitted to immersion were submerged in the vehicles without brushing. For brushed specimens, procedures were conducted using a linear brushing machine with a soft-bristled toothbrush. Immersion and brushing were performed for 244 h. IFT and BFT samples were analysed under scanning electron microscope with Energy-Dispersive X-ray Spectroscopy (EDS). Pre and post-treatment values were compared using the paired Student T-test (α=.05). Intergroup comparisons were conducted using one-way ANOVA with Tukey post-test (α=.05). cp Ti mean roughness (in nanometers) comparing pre and post-treatment were: IW, 2.29±0.55/2.33±0.17; IT, 2.24±0.46/2.02±0.38; IFT, 2.22±0.53/1.95±0.36; BW, 2.22±0.42/3.76±0.45; BT, 2.27±0.55/16.05±3.25; BFT, 2.27±0.51/22.39±5.07. Mean roughness (in nanometers) measured in Ti-6Al-4V disks (pre/post-treatment) were: IW, 1.79±0.25/2.01±0.25; IT, 1.61±0.13/1.74±0.19; IFT, 1.92±0.39/2.29±0.51; BW, 2.00±0.71/2.05±0.43; BT, 2.37±0.86/11.17±2.29; BFT, 1.83±0.50/15.73±1.78. No significant differences were seen after immersions (p>.05). Brushing increased the roughness of cp Ti and of Ti-6Al-4V (p<.01); cp Ti had topographic changes after BW, BT and BFT treatments whilst Ti-6Al-4V was significantly different only after BT and BTF. EDS has not detected fluoride or sodium ions on metal surfaces. Exposure to toothpastes (immersion

Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces.

Science.gov (United States)

Ziebart, Thomas; Schnell, Anne; Walter, Christian; Kämmerer, Peer W; Pabst, Andreas; Lehmann, Karl M; Ziebart, Johanna; Klein, Marc O; Al-Nawas, Bilal

2013-01-01

Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces. EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction. Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces. The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities. In

Surface modification of titanium and titanium alloys by ion implantation.

Science.gov (United States)

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

2010-05-01

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

Surface roughness of Ti6Al4V after heat treatment evaluated by artificial neural networks

Energy Technology Data Exchange (ETDEWEB)

Altug, Mehmet [Inonu Univ., Malataya (Turkey). Dept. of Machine and Metal Technologies; Erdem, Mehmet; Bozkir, Oguz [Inonu Univ., Malataya (Turkey); Ozay, Cetin [Univ. of Firat Elazig (Turkey). Faculty of Tech. Education

2016-05-01

The study examines how, using wire electrical discharge machining (WEDM), the microstructural, mechanical and conductivity characteristics of the titanium alloy Ti6Al4V are changed as a result of heat treatment and the effect they have on machinability. Scanning electron microscope (SEM), optical microscope and X-ray diffraction (XRD) examinations were performed to determine various characteristics and additionally related microhardness and conductivity measurements were conducted. L{sub 18} Taquchi test design was performed with three levels and six different parameters to determine the effect of such alterations on its machinability using WEDM and post-processing surface roughness (Ra) values were determined. Micro-changes were ensured successfully by using heat treatments. Results obtained with the optimization technique of artificial neural network (ANN) presented minimum surface roughness. Values obtained by using response surface method along with this equation were completely comparable with those achieved in the experiments. The best surface roughness value was obtained from sample D which had a tempered martensite structure.

Analysis of surface roughness and cutting force during turning of Ti6Al4V ELI in dry environment

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V. G. Sargade

2016-04-01

Full Text Available This paper investigates the effect of cutting parameters on the surface roughness and cutting force of titanium alloy Ti-6Al-4V ELI when turning using PVD TiAlN coated tool in dry environment. Taguchi L9 orthogonal array design of experiment was used for the turning experiment 2 factors and 3 levels. Turning parameters studied were cutting speed (50, 65, 80 m/min, feed rate (0.08, 0.15, 0.2 mm/rev and depth of cut 0.5 mm constant. Linear and second order model of the surface roughness and cutting force has been developed in terms of cutting speed and feed. The results show that the feed rate was the most impact factor controlling the cutting force and surface roughness produced. MINITAB 17software was used to develop a linear and second order model of surface roughness and cutting force. Optimum condition was at 66.97 m/min of cutting speed, 0.08 mm/rev of feed rate. Surface roughness 0.57μm and cutting force 54.02 N were obtained at the optimum condition. A good agreement between the experimental and predicted surface roughness and cutting force were observed.

Physicochemical properties and in vitro cytocompatibility of modified titanium surfaces prepared via micro-arc oxidation with different calcium concentrations

International Nuclear Information System (INIS)

Wu, Sui-Dan; Zhang, Hui; Dong, Xu-Dong; Ning, Cheng-Yun; Fok, Alex S.L.; Wang, Yan

2015-01-01

Highlights: • MAO coating improves the surface characteristics and cytocompatibility of titanium. • Composition of MAO coating varies with the electrolyte concentration. • MAO coating properties can be optimized by adjusting the electrolyte concentration. • Higher CA concentration contributes to more favorable MAO coating cytocompatibility. - Abstract: Objective: To explore the effect of calcium concentration in the electrolyte solution on the physicochemical properties and biocompatibility of coatings formed by micro-arc oxidation (MAO) on titanium surfaces. Methods: The surfaces of pure titanium plates were modified by MAO in an electrolytic solution containing calcium acetate (CA; C 4 H 6 CaO 4 ) at concentrations of 0.05, 0.1, 0.2, or 0.3 M and β-glycerophosphate disodium salt pentahydrate (β-GP; C 3 H 7 Na 2 O 6 P·5H 2 O) at a fixed concentration of 0.02 M. Surface topography, elemental characteristics, phase composition, and roughness were investigated by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, and a surface roughness tester, respectively. To assess the cytocompatibility and osteoinductivity of the surfaces, MC3T3-E1 preosteoblasts were cultured on the surfaces in vitro, and cell morphology, adhesion, proliferation, and differentiation were observed. Results: The porous MAO coating was composed primarily of TiO 2 rutile and anatase. The amount of TiO 2 rutile, the Ca/P ratio, and the surface roughness of the MAO coating increased with increasing CA concentration in the electrolyte solution. Ca 3 (PO 4 ) 2 , CaCO 3 , and CaTiO 3 were formed on MAO-treated surfaces prepared with CA concentrations of 0.2 and 0.3 M. Cell proliferation and differentiation increased with increasing CA concentration, with MC3T3-E1 cells exhibiting favorable morphologies for bone–implant integration. Conclusions: MAO coating improves the surface characteristics and cytocompatibility of titanium for osseointegration. Higher CA

Surface correlations of hydrodynamic drag for transitionally rough engineering surfaces

Science.gov (United States)

Thakkar, Manan; Busse, Angela; Sandham, Neil

2017-02-01

Rough surfaces are usually characterised by a single equivalent sand-grain roughness height scale that typically needs to be determined from laboratory experiments. Recently, this method has been complemented by a direct numerical simulation approach, whereby representative surfaces can be scanned and the roughness effects computed over a range of Reynolds number. This development raises the prospect over the coming years of having enough data for different types of rough surfaces to be able to relate surface characteristics to roughness effects, such as the roughness function that quantifies the downward displacement of the logarithmic law of the wall. In the present contribution, we use simulation data for 17 irregular surfaces at the same friction Reynolds number, for which they are in the transitionally rough regime. All surfaces are scaled to the same physical roughness height. Mean streamwise velocity profiles show a wide range of roughness function values, while the velocity defect profiles show a good collapse. Profile peaks of the turbulent kinetic energy also vary depending on the surface. We then consider which surface properties are important and how new properties can be incorporated into an empirical model, the accuracy of which can then be tested. Optimised models with several roughness parameters are systematically developed for the roughness function and profile peak turbulent kinetic energy. In determining the roughness function, besides the known parameters of solidity (or frontal area ratio) and skewness, it is shown that the streamwise correlation length and the root-mean-square roughness height are also significant. The peak turbulent kinetic energy is determined by the skewness and root-mean-square roughness height, along with the mean forward-facing surface angle and spanwise effective slope. The results suggest feasibility of relating rough-wall flow properties (throughout the range from hydrodynamically smooth to fully rough) to surface

Laser and chemical surface modifications of titanium grade 2 for medical application

Energy Technology Data Exchange (ETDEWEB)

Kwaśniak, P. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Pura, J., E-mail: jaroslawpura@gmail.com [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Zwolińska, M.; Wieciński, P. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Skarżyński, H.; Olszewski, L. [Institute of Physiology and Pathology of Hearing, Warsaw (Poland); World Hearing Center, Kajetany (Poland); Marczak, J. [Military University of Technology, Institute of Optoelectronics, Warsaw (Poland); Garbacz, H.; Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland)

2015-05-01

Highlights: • DLIL technique and etching were used for functionalization of Ti grade 2 surface. • Modification was performed on semi-finished flat and curved Ti surfaces. • Modification results in periodic multimodal (micro and nano-size) Ti topography. - Abstract: The article presents combined, chemical and physical approach to titanium surface functionalization designed for biomedical applications. The topography modification has been obtained by employing the double laser beam interference technique and chemical etching. In the outcome, clean and smooth Ti surface as well as periodic striated topography with the roughness range from nano- to micrometers were created. The obtained structures were characterized in terms of shape, roughness, chemical composition, mechanical properties and microstructures. In order to achieve all information, numerous of research methods have been used: scanning electron microscopy, atomic force microscopy, optical profilometry and microhardness measurements. Demonstrated methodology can be used as an effective tool for manufacturing controlled surface structures improving the bone–implants interactions.

Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

Science.gov (United States)

Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

2018-01-01

To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published

Hydrogen content in titanium and a titanium–zirconium alloy after acid etching

Energy Technology Data Exchange (ETDEWEB)

Frank, Matthias J.; Walter, Martin S. [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Lyngstadaas, S. Petter [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Wintermantel, Erich [Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway)

2013-04-01

Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium–zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p < 0.01) on the titanium–zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium. - Highlights: ► TiZr alloy showed increased hydrogen levels over Ti. ► The alloying element Zr appeared to catalyze hydrogen absorption in Ti. ► Surface roughness was significantly increased for the TiZr alloy over Ti. ► TiZr alloy revealed nanostructures not observed for Ti.

IMPACT OF VIBRATORY AND ROTATIONAL SHOT PEENING ONTO SELECTED PROPERTIES OF TITANIUM ALLOY SURFACE LAYER

Directory of Open Access Journals (Sweden)

Kazimierz Zaleski

2014-06-01

Full Text Available This study presents the results of tests on impact of vibratory and rotational shot peening of the Ti6A12Mo2Cr titanium alloy onto the processed object surface roughness and surface layer microhardness. The external surfaces of ring-shaped samples were shot peened. The preceding process consisted of turning with a cubic boron nitride blade knife. Steel beads, having a diameter of 6 mm, were used as a processing medium. The variable parameters of shot peening were vibrator amplitude and shot peening time. The range of recommended technological parameters for vibratory and rotational shot peening was determined. As a result of shot peening, the surface roughness could be reduced by approximately 4 times and the surface layer could be hardened to the depth of approximately 0.4 mm.

Development of titanium alloys and surface treatments to increase the implants lifetime

Directory of Open Access Journals (Sweden)

Joan Lario-Femenía

2016-12-01

Full Text Available The population aging together with increase of life expectancy forces the development of new prosthesis which may present a higher useful life. The clinical success of implants is based on the osseointegration achievement. Therefore, metal implants must have a mechanical compatibility with the substituted bone, which is achieved through a combination of low elastic modulus, high flexural and fatigue strength. The improvement, in the short and long term, of the osseointegration depends on several factors, where the macroscopic design and dimensional, material and implant surface topography are of great importance. This article is focused on summarizing the advantages that present the titanium and its alloys to be used as biomaterials, and the development that they have suffered in recent decades to improve their biocompatibility. Consequently, the implants evolution has been recapitulated and summarized through three generations. In the recent years the interest on the surface treatments for metallic prostheses has been increased, the main objective is achieve a lasting integration between implant and bone tissue, in the shortest time possible. On this article various surface treatments currently used to modify the surface roughness or to obtain coatings are described it; it is worthy to mention the electrochemical oxidation with post-heat treated to modify the titanium oxide crystalline structure. After the literature review conducted for prepare this article, the ? titanium alloys, with a nanotubes surface of obtained by electrochemical oxidation and a subsequent step of heat treatment to obtain a crystalline structure are the future option to improve long term biocompatibility of titanium prostheses.

Physicochemical properties and in vitro cytocompatibility of modified titanium surfaces prepared via micro-arc oxidation with different calcium concentrations

Energy Technology Data Exchange (ETDEWEB)

Wu, Sui-Dan; Zhang, Hui [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Dong, Xu-Dong [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3 (Canada); Ning, Cheng-Yun [College of Material Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Fok, Alex S.L. [Minnesota Dental Research Center of Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN 55414 (United States); Wang, Yan, E-mail: wyan65@163.com [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China)

2015-02-28

Highlights: • MAO coating improves the surface characteristics and cytocompatibility of titanium. • Composition of MAO coating varies with the electrolyte concentration. • MAO coating properties can be optimized by adjusting the electrolyte concentration. • Higher CA concentration contributes to more favorable MAO coating cytocompatibility. - Abstract: Objective: To explore the effect of calcium concentration in the electrolyte solution on the physicochemical properties and biocompatibility of coatings formed by micro-arc oxidation (MAO) on titanium surfaces. Methods: The surfaces of pure titanium plates were modified by MAO in an electrolytic solution containing calcium acetate (CA; C{sub 4}H{sub 6}CaO{sub 4}) at concentrations of 0.05, 0.1, 0.2, or 0.3 M and β-glycerophosphate disodium salt pentahydrate (β-GP; C{sub 3}H{sub 7}Na{sub 2}O{sub 6}P·5H{sub 2}O) at a fixed concentration of 0.02 M. Surface topography, elemental characteristics, phase composition, and roughness were investigated by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, and a surface roughness tester, respectively. To assess the cytocompatibility and osteoinductivity of the surfaces, MC3T3-E1 preosteoblasts were cultured on the surfaces in vitro, and cell morphology, adhesion, proliferation, and differentiation were observed. Results: The porous MAO coating was composed primarily of TiO{sub 2} rutile and anatase. The amount of TiO{sub 2} rutile, the Ca/P ratio, and the surface roughness of the MAO coating increased with increasing CA concentration in the electrolyte solution. Ca{sub 3}(PO{sub 4}){sub 2}, CaCO{sub 3}, and CaTiO{sub 3} were formed on MAO-treated surfaces prepared with CA concentrations of 0.2 and 0.3 M. Cell proliferation and differentiation increased with increasing CA concentration, with MC3T3-E1 cells exhibiting favorable morphologies for bone–implant integration. Conclusions: MAO coating improves the surface characteristics and

Rock discontinuity surface roughness variation with scale

Science.gov (United States)

Bitenc, Maja; Kieffer, D. Scott; Khoshelham, Kourosh

2017-04-01

ABSTRACT: Rock discontinuity surface roughness refers to local departures of the discontinuity surface from planarity and is an important factor influencing the shear resistance. In practice, the Joint Roughness Coefficient (JRC) roughness parameter is commonly relied upon and input to a shear strength criterion such as developed by Barton and Choubey [1977]. The estimation of roughness by JRC is hindered firstly by the subjective nature of visually comparing the joint profile to the ten standard profiles. Secondly, when correlating the standard JRC values and other objective measures of roughness, the roughness idealization is limited to a 2D profile of 10 cm length. With the advance of measuring technologies that provide accurate and high resolution 3D data of surface topography on different scales, new 3D roughness parameters have been developed. A desirable parameter is one that describes rock surface geometry as well as the direction and scale dependency of roughness. In this research a 3D roughness parameter developed by Grasselli [2001] and adapted by Tatone and Grasselli [2009] is adopted. It characterizes surface topography as the cumulative distribution of local apparent inclination of asperities with respect to the shear strength (analysis) direction. Thus, the 3D roughness parameter describes the roughness amplitude and anisotropy (direction dependency), but does not capture the scale properties. In different studies the roughness scale-dependency has been attributed to data resolution or size of the surface joint (see a summary of researches in [Tatone and Grasselli, 2012]). Clearly, the lower resolution results in lower roughness. On the other hand, have the investigations of surface size effect produced conflicting results. While some studies have shown a decrease in roughness with increasing discontinuity size (negative scale effect), others have shown the existence of positive scale effects, or both positive and negative scale effects. We

Three-tier rough superhydrophobic surfaces

International Nuclear Information System (INIS)

Cao, Yuanzhi; Yuan, Longyan; Hu, Bin; Zhou, Jun

2015-01-01

A three-tier rough superhydrophobic surface was fabricated by growing hydrophobic modified (fluorinated silane) zinc oxide (ZnO)/copper oxide (CuO) hetero-hierarchical structures on silicon (Si) micro-pillar arrays. Compared with the other three control samples with a less rough tier, the three-tier surface exhibits the best water repellency with the largest contact angle 161° and the lowest sliding angle 0.5°. It also shows a robust Cassie state which enables the water to flow with a speed over 2 m s"−"1. In addition, it could prevent itself from being wetted by the droplet with low surface tension (mixed water and ethanol 1:1 in volume) which reveals a flow speed of 0.6 m s"−"1 (dropped from the height of 2 cm). All these features prove that adding another rough tier on a two-tier rough surface could futher improve its water-repellent properties. (paper)

Surface modification of the titanium implant using TEA CO2 laser pulses in controllable gas atmospheres - Comparative study

International Nuclear Information System (INIS)

Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D.; Bokorov, M.; Trtica, M.

2012-01-01

Interaction of a TEA CO 2 laser, operating at 10.6 μm wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm 2 in the surrounding of air, N 2 , O 2 or He. The energy absorbed from the TEA CO 2 laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N 2 and O 2 , and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

Dissolution of minerals with rough surfaces

Science.gov (United States)

de Assis, Thiago A.; Aarão Reis, Fábio D. A.

2018-05-01

We study dissolution of minerals with initial rough surfaces using kinetic Monte Carlo simulations and a scaling approach. We consider a simple cubic lattice structure, a thermally activated rate of detachment of a molecule (site), and rough surface configurations produced by fractional Brownian motion algorithm. First we revisit the problem of dissolution of initial flat surfaces, in which the dissolution rate rF reaches an approximately constant value at short times and is controlled by detachment of step edge sites. For initial rough surfaces, the dissolution rate r at short times is much larger than rF ; after dissolution of some hundreds of molecular layers, r decreases by some orders of magnitude across several time decades. Meanwhile, the surface evolves through configurations of decreasing energy, beginning with dissolution of isolated sites, then formation of terraces with disordered boundaries, their growth, and final smoothing. A crossover time to a smooth configuration is defined when r = 1.5rF ; the surface retreat at the crossover is approximately 3 times the initial roughness and is temperature-independent, while the crossover time is proportional to the initial roughness and is controlled by step-edge site detachment. The initial dissolution process is described by the so-called rough rates, which are measured for fixed ratios between the surface retreat and the initial roughness. The temperature dependence of the rough rates indicates control by kink site detachment; in general, it suggests that rough rates are controlled by the weakest microscopic bonds during the nucleation and formation of the lowest energy configurations of the crystalline surface. Our results are related to recent laboratory studies which show enhanced dissolution in polished calcite surfaces. In the application to calcite dissolution in alkaline environment, the minimal values of recently measured dissolution rate spectra give rF ∼10-9 mol/(m2 s), and the calculated rate

A Study on Kaolin and Titanium dioxide affecting Physical Properties of Electrocoating

International Nuclear Information System (INIS)

Yang, Wonseog; Hwang, Woonsuk

2013-01-01

The electrocoating for automotive bodies is pigmented with a mixture of titanium dioxide and kaolin. In this study, the effects of titanium dioxide and kaolin contents in coating on electrodeposition process, drying, and surface properties such as surface roughness, gloss, impact resistance and corrosion resistance were investigated. Titanium dioxide and kaolin in coating do not have a decisive effect on curing reaction during drying and corrosion resistance but on gloss, surface roughness, impact resistance and electrodeposition process of coating. According to its size and shape on coating surface, pigment contents increased during drying process. However, the contents of kaolin and TiO 2 in coating didn't affect the corrosion resistance on zinc phosphated substrate, and the curing properties

Towards predictive models for transitionally rough surfaces

Science.gov (United States)

Abderrahaman-Elena, Nabil; Garcia-Mayoral, Ricardo

2017-11-01

We analyze and model the previously presented decomposition for flow variables in DNS of turbulence over transitionally rough surfaces. The flow is decomposed into two contributions: one produced by the overlying turbulence, which has no footprint of the surface texture, and one induced by the roughness, which is essentially the time-averaged flow around the surface obstacles, but modulated in amplitude by the first component. The roughness-induced component closely resembles the laminar steady flow around the roughness elements at the same non-dimensional roughness size. For small - yet transitionally rough - textures, the roughness-free component is essentially the same as over a smooth wall. Based on these findings, we propose predictive models for the onset of the transitionally rough regime. Project supported by the Engineering and Physical Sciences Research Council (EPSRC).

Influence of Nitrogen Flow Rate on Friction Coefficient and Surface Roughness of TiN Coatings Deposited on Tool Steel Using Arc Method

Science.gov (United States)

Hamzah, Esah; Ourdjini, Ali; Ali, Mubarak; Akhter, Parvez; Hj. Mohd Toff, Mohd Radzi; Abdul Hamid, Mansor

In the present study, the effect of various N2 gas flow rates on friction coefficient and surface roughness of TiN-coated D2 tool steel was examined by a commercially available cathodic arc physical vapor deposition (CAPVD) technique. A Pin-on-Disc test was carried out to study the Coefficient of friction (COF) versus sliding distance. A surface roughness tester measured the surface roughness parameters. The minimum values for the COF and surface roughness were recorded at a N2 gas flow rate of 200 sccm. The increase in the COF and surface roughness at a N2 gas flow rate of 100 sccm was mainly attributed to an increase in both size and number of titanium particles, whereas the increase at 300 sccm was attributed to a larger number of growth defects generated during the coating process. These ideas make it possible to optimize the coating properties as a function of N2 gas flow rate for specific applications, e.g. cutting tools for automobiles, aircraft, and various mechanical parts.

Osteogenic potential of laser modified and conditioned titanium zirconium surfaces

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P David Charles

2016-01-01

Full Text Available Statement of Problem: The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established. Purpose: The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG laser surface treatment of TiZr implant alloy on their osteogenic potential. Materials and Methods: Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy. Results: Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential. Conclusion: Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.

Effects of titanium surface topography on bone integration: a systematic review.

Science.gov (United States)

Wennerberg, Ann; Albrektsson, Tomas

2009-09-01

To analyse possible effects of titanium surface topography on bone integration. Our analyses were centred on a PubMed search that identified 1184 publications of assumed relevance; of those, 1064 had to be disregarded because they did not accurately present in vivo data on bone response to surface topography. The remaining 120 papers were read and analysed, after removal of an additional 20 papers that mainly dealt with CaP-coated and Zr implants; 100 papers remained and formed the basis for this paper. The bone response to differently configurated surfaces was mainly evaluated by histomorphometry (bone-to-implant contact), removal torque and pushout/pullout tests. A huge number of the experimental investigations have demonstrated that the bone response was influenced by the implant surface topography; smooth (S(a)1-2 microm) surfaces showed stronger bone responses than rough (S(a)>2 microm) in some studies. One limitation was that it was difficult to compare many studies because of the varying quality of surface evaluations; a surface termed 'rough' in one study was not uncommonly referred to as 'smooth' in another; many investigators falsely assumed that surface preparation per se identified the roughness of the implant; and many other studies used only qualitative techniques such as SEM. Furthermore, filtering techniques differed or only height parameters (S(a), R(a)) were reported. * Surface topography influences bone response at the micrometre level. * Some indications exist that surface topography influences bone response at the nanometre level. * The majority of published papers present an inadequate surface characterization. * Measurement and evaluation techniques need to be standardized. * Not only height descriptive parameters but also spatial and hybrid ones should be used.

Characterisation of surface roughness for ultra-precision freeform surfaces

International Nuclear Information System (INIS)

Li Huifen; Cheung, C F; Lee, W B; To, S; Jiang, X Q

2005-01-01

Ultra-precision freeform surfaces are widely used in many advanced optics applications which demand for having surface roughness down to nanometer range. Although a lot of research work has been reported on the study of surface generation, reconstruction and surface characterization such as MOTIF and fractal analysis, most of them are focused on axial symmetric surfaces such as aspheric surfaces. Relative little research work has been found in the characterization of surface roughness in ultra-precision freeform surfaces. In this paper, a novel Robust Gaussian Filtering (RGF) method is proposed for the characterisation of surface roughness for ultra-precision freeform surfaces with known mathematic model or a cloud of discrete points. A series of computer simulation and measurement experiments were conducted to verify the capability of the proposed method. The experimental results were found to agree well with the theoretical results

Electropolished Titanium Implants with a Mirror-Like Surface Support Osseointegration and Bone Remodelling

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Cecilia Larsson Wexell

2016-01-01

Full Text Available This work characterises the ultrastructural composition of the interfacial tissue adjacent to electropolished, commercially pure titanium implants with and without subsequent anodisation, and it investigates whether a smooth electropolished surface can support bone formation in a manner similar to surfaces with a considerably thicker surface oxide layer. Screw-shaped implants were electropolished to remove all topographical remnants of the machining process, resulting in a thin spontaneously formed surface oxide layer and a smooth surface. Half of the implants were subsequently anodically oxidised to develop a thickened surface oxide layer and increased surface roughness. Despite substantial differences in the surface physicochemical properties, the microarchitecture and the composition of the newly formed bone were similar for both implant surfaces after 12 weeks of healing in rabbit tibia. A close spatial relationship was observed between osteocyte canaliculi and both implant surfaces. On the ultrastructural level, the merely electropolished surface showed the various stages of bone formation, for example, matrix deposition and mineralisation, entrapment of osteoblasts within the mineralised matrix, and their morphological transformation into osteocytes. The results demonstrate that titanium implants with a mirror-like surface and a thin, spontaneously formed oxide layer are able to support bone formation and remodelling.

Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

Science.gov (United States)

Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

2016-08-01

Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

Nano- and Micro-Scale Oxidative Patterning of Titanium Implant Surfaces for Improved Surface Wettability.

Science.gov (United States)

Kim, In-hye; Son, Jun Sik; Choi, Seok Hwa; Kim, Kyo-han; Kwon, Tae-yub

2016-02-01

A simple and scalable surface modification treatment is demonstrated, in which nano- and microscale features are introduced into the surface of titanium (Ti) substrates by means of a novel and eco-friendly oxidative aqueous solution composed of hydrogen peroxide (H202) and sodium bicarbonate (NaHCO3). By immersing mirror-polished Ti discs in an aqueous mixture of 30 wt% H2O2/5 wt% NaHCO3 at 23 +/- 3 degrees C for 4 h, it was confirmed that this mixture is capable of generating microscale topographies on Ti surfaces. It also simultaneously formed nanochannels that were regularly arranged in a comb-like pattern on the Ti surface, thus forming a hierarchical surface structure. Further, these nano/micro-textured Ti surfaces showed great surface roughness and excellent wettability when compared with control Ti surfaces. This study demonstrates that a H2O2/NaHCO3 mixture can be effectively utilized to create reproducible nano/microscale topographies on Ti implant surfaces, thus providing an economical new oxidative solution that may be used effectively and safely as a Ti surface modification treatment.

Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

International Nuclear Information System (INIS)

Bathomarco, R.V.; Solorzano, G.; Elias, C.N.; Prioli, R.

2004-01-01

The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle

Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

Science.gov (United States)

Bathomarco, Ti R. V.; Solorzano, G.; Elias, C. N.; Prioli, R.

2004-06-01

The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle.

Electro-chemical deposition of nano hydroxyapatite-zinc coating on titanium metal substrate.

Science.gov (United States)

El-Wassefy, N A; Reicha, F M; Aref, N S

2017-08-13

Titanium is an inert metal that does not induce osteogenesis and has no antibacterial properties; it is proposed that hydroxyapatite coating can enhance its bioactivity, while zinc can contribute to antibacterial properties and improve osseointegration. A nano-sized hydroxyapatite-zinc coating was deposited on commercially pure titanium using an electro-chemical process, in order to increase its surface roughness and enhance adhesion properties. The hydroxyapatite-zinc coating was attained using an electro-chemical deposition in a solution composed of a naturally derived calcium carbonate, di-ammonium hydrogen phosphate, with a pure zinc metal as the anode and titanium as the cathode. The applied voltage was -2.5 for 2 h at a temperature of 85 °C. The resultant coating was characterized for its surface morphology and chemical composition using a scanning electron microscope (SEM), energy dispersive x-ray spectroscope (EDS), and Fourier transform infrared (FT-IR) spectrometer. The coated specimens were also evaluated for their surface roughness and adhesion quality. Hydroxyapatite-zinc coating had shown rosette-shaped, homogenous structure with nano-size distribution, as confirmed by SEM analysis. FT-IR and EDS proved that coatings are composed of hydroxyapatite (HA) and zinc. The surface roughness assessment revealed that the coating procedure had significantly increased average roughness (Ra) than the control, while the adhesive tape test demonstrated a high-quality adhesive coat with no laceration on tape removal. The developed in vitro electro-chemical method can be employed for the deposition of an even thickness of nano HA-Zn adhered coatings on titanium substrate and increases its surface roughness significantly.

Superficial characterization of titanium league when submitted to abrasive blasting

International Nuclear Information System (INIS)

Suzuki, L.Y.; Leite, I.V.; Szesz, E.M.; Siqueira, C.J.M.

2010-01-01

Commercially pure titanium and some of its alloys exhibit a good biocompatibility. These characteristics are frequently used in the manufacture of orthopedic and dental implants. It is possible to modify its surface making it the bioactive using various methods, such as deposition of hydroxyapatite by plasma spray and increasing the roughness of the surface by abrasive blasting. This work is to modify the surface of titanium alloy Ti6Al4V ELI (ASTM F136: 02a) for abrasive blasting and study the morphology, crystallographic phases and the mechanical characteristics of the surface obtained. For such purpose, SEM images, diffraction of X-rays and tests of risk produced by nanoindenter. The sandblasting was done using alumina powder and blasting time of 6s. The morphology of the surfaces of Ti6Al4V ELI changed after sandblasting with increased roughness. It is possible to conclude that after sandblasting the titanium surface do not have a ductile behavior. (author)

Bacterial attachment on titanium surfaces is dependent on topography and chemical changes induced by nonthermal atmospheric pressure plasma.

Science.gov (United States)

Jeong, Won-Seok; Kwon, Jae-Sung; Lee, Jung-Hwan; Uhm, Soo-Hyuk; Ha Choi, Eun; Kim, Kwang-Mahn

2017-07-26

Here, we investigated the antibacterial effects of chemical changes induced by nonthermal atmospheric pressure plasma (NTAPP) on smooth and rough Ti. The morphologies of smooth and rough surfaces of Ti were examined using scanning electron microscopy (SEM). Both Ti specimens were then treated for 10 min by NTAPP with nitrogen gas. The surface roughness, chemistry, and wettability were examined by optical profilometry, x-ray photoelectron spectroscopy, and water contact angle analysis, respectively. Bacterial attachment was measured by determining the number of colony forming units and by SEM analysis. The rough Ti showed irregular micropits, whereas smooth Ti had a relatively regular pattern on the surface. There were no differences in morphology between samples before and after NTAPP treatment. NTAPP treatment resulted in changes from hydrophobic to hydrophilic properties on rough and smooth Ti; rough Ti showed relatively higher hydrophilicity. Before NTAPP treatment, Streptococcus sanguinis (S. sanguinis) showed greater attachment on rough Ti, and after NTAPP treatment, there was a significant reduction in bacterial attachment. Moreover, the bacterial attachment rate was significantly lower on rough Ti, and the structure of S. sanguinis colonies were significantly changed on NTAPP-treated Ti. NTAPP treatment inhibited bacterial attachment surrounding titanium implants, regardless of surface topography. Therefore, NTAPP treatment on Ti is a next-generation tool for antibacterial applications in the orthopaedic and dental fields.

Surface modification of TA2 pure titanium by low energy high current pulsed electron beam treatments

International Nuclear Information System (INIS)

Gao Yukui

2011-01-01

Surface integrity changes of TA2 pure titanium including surface topography, microstructure and nanohardness distribution along surface layer were investigated by different techniques of low energy high current pulsed electron beam treatments (LEHCPEBTs). The surface topography was characterized by SEM. Moreover, the TEM observation and X-ray diffraction analysis were performed to reveal the surface modification mechanism of TA2 pure titanium by LEHCPEBTs. The surface roughness was modified by electron beam treatment and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM and TEM. The results show that the surface finish obtains good polishing quality and there is no phase transformation but the dislocations by LEHCPEBT. Furthermore, the nanohardness in the surface modified layer is improved. The remelt and fine-grain microstructure of surface layer caused by LEHCPEBTs are the main polishing mechanism and the reason of modification of surface topography and the increment in nanohardness is mainly due to the dislocations and fine grains in the modified layer induced by LEHCPEBT.

Establishing Antibacterial Multilayer Films on the Surface of Direct Metal Laser Sintered Titanium Primed with Phase-Transited Lysozyme

Science.gov (United States)

Guan, Binbin; Wang, Haorong; Xu, Ruiqing; Zheng, Guoying; Yang, Jie; Liu, Zihao; Cao, Man; Wu, Mingyao; Song, Jinhua; Li, Neng; Li, Ting; Cai, Qing; Yang, Xiaoping; Li, Yanqiu; Zhang, Xu

2016-11-01

Direct metal laser sintering is a technology that allows the fabrication of titanium (Ti) implants with a functional gradation of porosity and surface roughness according to three-dimensional (3D) computer data. The surface roughness of direct metal laser sintered titanium (DMLS-Ti) implants may provide abundant binding sites for bacteria. Bacterial colonization and subsequent biofilm formation can cause unsatisfactory cell adhesion and implant-related infections. To prevent such infections, a novel phase-transited lysozyme (PTL) was utilized as an initial functional layer to simply and effectively prime DMLS-Ti surfaces for subsequent coating with antibacterial multilayers. The purpose of the present study was to establish a surface with dual biological functionality. The minocycline-loaded polyelectrolyte multilayers of hyaluronic acid (HA) and chitosan (CS) formed via a layer-by-layer (LbL) self-assembly technique on PTL-functionalized DMLS-Ti were designed to inhibit pathogenic microbial infections while allowing the DMLS-Ti itself and the modified coatings to retain acceptable biocompatibility. The experimental results indicate that the DMLS-Ti and the hydrogel treated surfaces can inhibit early bacterial adhesion while completely preserving osteoblast functions. This design is expected to gain considerable interest in the medical field and to have good potential for applications in multifunctional DMLS-Ti implants.

Establishing Antibacterial Multilayer Films on the Surface of Direct Metal Laser Sintered Titanium Primed with Phase-Transited Lysozyme.

Science.gov (United States)

Guan, Binbin; Wang, Haorong; Xu, Ruiqing; Zheng, Guoying; Yang, Jie; Liu, Zihao; Cao, Man; Wu, Mingyao; Song, Jinhua; Li, Neng; Li, Ting; Cai, Qing; Yang, Xiaoping; Li, Yanqiu; Zhang, Xu

2016-11-08

Direct metal laser sintering is a technology that allows the fabrication of titanium (Ti) implants with a functional gradation of porosity and surface roughness according to three-dimensional (3D) computer data. The surface roughness of direct metal laser sintered titanium (DMLS-Ti) implants may provide abundant binding sites for bacteria. Bacterial colonization and subsequent biofilm formation can cause unsatisfactory cell adhesion and implant-related infections. To prevent such infections, a novel phase-transited lysozyme (PTL) was utilized as an initial functional layer to simply and effectively prime DMLS-Ti surfaces for subsequent coating with antibacterial multilayers. The purpose of the present study was to establish a surface with dual biological functionality. The minocycline-loaded polyelectrolyte multilayers of hyaluronic acid (HA) and chitosan (CS) formed via a layer-by-layer (LbL) self-assembly technique on PTL-functionalized DMLS-Ti were designed to inhibit pathogenic microbial infections while allowing the DMLS-Ti itself and the modified coatings to retain acceptable biocompatibility. The experimental results indicate that the DMLS-Ti and the hydrogel treated surfaces can inhibit early bacterial adhesion while completely preserving osteoblast functions. This design is expected to gain considerable interest in the medical field and to have good potential for applications in multifunctional DMLS-Ti implants.

Investigation on Surface Roughness in Cylindrical Grinding

Science.gov (United States)

Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

2011-01-01

Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

The Importance Of Surface Topography For The Biological Properties Of Nitrided Diffusion Layers Produced On Ti6Al4V Titanium Alloy

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Wierzchoń T.

2015-09-01

Full Text Available Diffusion nitrided layers produced on titanium and its alloys are widely studied in terms of their application for cardiac and bone implants. The influence of the structure, the phase composition, topography and surface morphology on their biological properties is being investigated. The article presents the results of a study of the topography (nanotopography of the surface of TiN+Ti2N+αTi(N nitrided layers produced in low-temperature plasma on Ti6Al4V titanium alloy and their influence on the adhesion of blood platelets and their aggregates. The TEM microstructure of the produced layers have been examined and it was demonstrated that the interaction between platelets and the surface of the titanium implants subjected to glow-discharge nitriding can be shaped via modification of the roughness parameters of the external layer of the TiN titanium nitride nanocrystalline zone.

Effect of different surface nanoroughness of titanium dioxide films on the growth of human osteoblast-like MG63 cells

Czech Academy of Sciences Publication Activity Database

Vandrovcová, Marta; Hanuš, J.; Drábik, M.; Kylián, O.; Biederman, H.; Lisá, Věra; Bačáková, Lucie

100A, č. 4 (2012), s. 1016-1032 ISSN 1549-3296 R&D Projects: GA AV ČR(CZ) KAN101120701 Institutional research plan: CEZ:AV0Z50110509 Keywords : titanium dioxide * nanoscale surface roughness * MG63 cells Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.834, year: 2012

Surface modification of the titanium implant using TEA CO{sub 2} laser pulses in controllable gas atmospheres - Comparative study

Energy Technology Data Exchange (ETDEWEB)

Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D. [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia); Bokorov, M. [Faculty of Sciences, Department of Biology and Ecology, University of Novi Sad, Trg Dositeja Obradovica 3, 21000 Novi Sad (Serbia); Trtica, M., E-mail: etrtica@vinca.rs [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia)

2012-01-15

Interaction of a TEA CO{sub 2} laser, operating at 10.6 {mu}m wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm{sup 2} in the surrounding of air, N{sub 2}, O{sub 2} or He. The energy absorbed from the TEA CO{sub 2} laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N{sub 2} and O{sub 2}, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

Application of Taguchi method to optimization of surface roughness during precise turning of NiTi shape memory alloy

Science.gov (United States)

Kowalczyk, M.

2017-08-01

This paper describes the research results of surface quality research after the NiTi shape memory alloy (Nitinol) precise turning by the tools with edges made of polycrystalline diamonds (PCD). Nitinol, a nearly equiatomic nickel-titanium shape memory alloy, has wide applications in the arms industry, military, medicine and aerospace industry, and industrial robots. Due to their specific properties NiTi alloys are known to be difficult-to-machine materials particularly by using conventional techniques. The research trials were conducted for three independent parameters (vc, f, ap) affecting the surface roughness were analyzed. The choice of parameter configurations were performed by factorial design methods using orthogonal plan type L9, with three control factors, changing on three levels, developed by G. Taguchi. S/N ratio and ANOVA analyses were performed to identify the best of cutting parameters influencing surface roughness.

Influence of surface roughness on the friction property of textured surface

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Yuankai Zhou

2015-02-01

Full Text Available In contrast with dimple textures, surface roughness is a texture at the micro-scale, essentially which will influence the load-bearing capacity of lubricant film. The numerical simulation was carried out to investigate the influence of surface roughness on friction property of textured surface. The lubricant film pressure was obtained using the method of computational fluid dynamics according to geometric model of round dimple, and the renormalization-group k–ε turbulent model was adopted in the computation. The numerical simulation results suggest that there is an optimum dimensionless surface roughness, and near this value, the maximum load-bearing capacity can be achieved. The load-bearing capacity is determined by the surface texture, the surface roughness, and the interaction between them. To get information of friction coefficient, the experiments were conducted. This experiment was used to evaluate the simulation. The experimental results show that for the frequency of 4 and 6 Hz, friction coefficient decreases at first and then increases with decreasing surface roughness, which indicates that there exists the optimum region of surface roughness leading to the best friction reduction effect, and it becomes larger when area fractions increase from 2% to 10%. The experimental results agree well with the simulation results.

Effect of nonthermal plasma treatment on surface chemistry of commercially-pure titanium and shear bond strength to autopolymerizing acrylic resin

Energy Technology Data Exchange (ETDEWEB)

Vechiato-Filho, Aljomar José, E-mail: aljomarvechiatoflo@gmail.com [Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Univ. Estadual Paulista — UNESP, Aracatuba, Sao Paulo (Brazil); Silva Vieira Marques, Isabella da [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Sao Paulo (Brazil); Santos, Daniela Micheline dos [Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Univ. Estadual Paulista — UNESP, Aracatuba, Sao Paulo (Brazil); Oliveira Matos, Adaias [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Sao Paulo (Brazil); Rangel, Elidiane Cipriano; Cruz, Nilson Cristino da [Laboratory of Technological Plasmas (LaPTec), Engineering College, Univ. Estadual Paulista — UNESP, Sorocaba, Sao Paulo (Brazil); Barão, Valentim Adelino Ricardo [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Sao Paulo (Brazil)

2016-03-01

The effect of nonthermal plasma on the surface characteristics of commercially pure titanium (cp-Ti), and on the shear bond strength between an autopolymerizing acrylic resin and cp-Ti was investigated. A total of 96 discs of cp-Ti were distributed into four groups (n = 24): Po (no surface treatment), SB (sandblasting), Po + NTP and SB + NTP (methane plasma). Surface characterization was performed through surface energy, surface roughness, scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction tests. Shear bond strength test was conducted immediately and after thermocycling. Surface treatment affected the surface energy and roughness of cp-Ti discs (P < .001). SEM–EDS showed the presence of the carbide thin film. XRD spectra revealed no crystalline phase changes. The SB + NTP group showed the highest bond strength values (6.76 ± 0.70 MPa). Thermocycling reduced the bond strength of the acrylic resin/cp-Ti interface (P < .05), except for Po group. NTP is an effective treatment option for improving the shear bond strength between both materials. - Highlights: • We tested the bond strength between two widely used materials in dentistry (acrylic and titanium). • We performed an innovative surface treatment with nonthermal plasma. • Increasing adhesion will avoid complications of full-arch implant-retained prostheses.

Role of surface roughness in superlubricity

International Nuclear Information System (INIS)

Tartaglino, U; Samoilov, V N; Persson, B N J

2006-01-01

We study the sliding of elastic solids in adhesive contact with flat and rough interfaces. We consider the dependence of the sliding friction on the elastic modulus of the solids. For elastically hard solids with planar surfaces with incommensurate surface structures we observe extremely low friction (superlubricity), which very abruptly increases as the elastic modulus decreases. We show that even a relatively small surface roughness may completely kill the superlubricity state

Modeling surface roughness scattering in metallic nanowires

Energy Technology Data Exchange (ETDEWEB)

Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [KU Leuven, Institute for Theoretical Physics, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); KU Leuven, Electrical Engineering (ESAT) Department, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Magnus, Wim [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

2015-09-28

Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

Numerical Investigation of Effect of Surface Roughness in a Microchannel

Energy Technology Data Exchange (ETDEWEB)

Shin, Myung Seob; Byun, Sung Jun; Yoon, Joon Yong [Hanyang University, Seoul (Korea, Republic of)

2010-05-15

In this paper, lattice Boltzmann method(LBM) results for a laminar flow in a microchannel with rough surface are presented. The surface roughness is modeled as an array of rectangular modules placed on the top and bottom surface of a parallel-plate channel. The effects of relative surface roughness, roughness distribution, and roughness size are presented in terms of the Poiseuille number. The roughness distribution characterized by the ratio of the roughness height to the spacing between the modules has a negligible effect on the flow and friction factors. Finally, a significant increase in the Poiseuille number is observed when the surface roughness is considered, and the effects of roughness on the microflow field mainly depend on the surface roughness.

Surface roughness effects on heat transfer in Couette flow

International Nuclear Information System (INIS)

Elia, G.G.

1981-01-01

A cell theory for viscous flow with rough surfaces is applied to two basic illustrative heat transfer problems which occur in Couette flow. Couette flow between one adiabatic surface and one isothermal surface exhibits roughness effects on the adiabatic wall temperature. Two types of rough cell adiabatic surfaces are studied: (1) perfectly insulating (the temperature gradient vanishes at the boundary of each cell); (2) average insulating (each cell may gain or lose heat but the total heat flow at the wall is zero). The results for the roughness on a surface in motion are postulated to occur because of fluid entrainment in the asperities on the moving surface. The symmetry of the roughness effects on thermal-viscous dissipation is discussed in detail. Explicit effects of the roughness on each surface, including combinations of roughness values, are presented to enable the case where the two surfaces may be from different materials to be studied. The fluid bulk temperature rise is also calculated for Couette flow with two ideal adiabatic surfaces. The effect of roughness on thermal-viscous dissipation concurs with the viscous hydrodynamic effect. The results are illustrated by an application to lubrication. (Auth.)

Bacterial adhesion studies on titanium, titanium nitride and modified hydroxyapatite thin films

Energy Technology Data Exchange (ETDEWEB)

Jeyachandran, Y L [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Venkatachalam, S [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Karunagaran, B [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Narayandass, Sa K [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Mangalaraj, D [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Bao, C Y [West China College of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, C L [West China College of Stomatology, Sichuan University, Chengdu 610041 (China)

2007-01-15

A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film.

Bacterial adhesion studies on titanium, titanium nitride and modified hydroxyapatite thin films

International Nuclear Information System (INIS)

Jeyachandran, Y.L.; Venkatachalam, S.; Karunagaran, B.; Narayandass, Sa.K.; Mangalaraj, D.; Bao, C.Y.; Zhang, C.L.

2007-01-01

A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film

Surface modification of TC4 titanium alloy by high current pulsed electron beam (HCPEB) with different pulsed energy densities

International Nuclear Information System (INIS)

Gao, Yu-kui

2013-01-01

Highlights: •The hardness changes were determined by nanoindention method. •The surface integrity changes were investigated by different techniques. •The mechanism was analyzed based on AFM and TEM investigations. -- Abstract: Surface changes including surface topography and nanohardness distribution along surface layer were investigated for TC4 titanium alloy by different energy densities of high current pulsed electron beam (HCPEB). The surface topography was characterized by SEM and AFM, and cross-sectional TEM observation was performed to reveal the surface modification mechanism of TC4 titanium alloy by HCPEB. The surface roughness was modified by HCPEB and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM. The fine grain structure inherited from the rapid solidification of the melted layer as well as the strain hardening of the sub-surface are two of the factors responsible the increase in nanohardness

Evaluation of the attachment, proliferation, and differentiation of osteoblast on a calcium carbonate coating on titanium surface

Energy Technology Data Exchange (ETDEWEB)

Liu Yi; Jiang Tao; Zhou Yi; Zhang Zhen; Wang Zhejun [Key Laboratory for Oral Biomedical Engineering, Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China); Tong Hua; Shen Xinyu [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Wang Yining, E-mail: wang.yn@whu.edu.cn [Key Laboratory for Oral Biomedical Engineering, Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China)

2011-07-20

Titanium has been reported to have some limitations in dental and orthopaedic clinical application. This study described a coating process using a simple chemical method to prepare calcium carbonate coatings on smooth titanium (STi) and sandblasted and acid-etched titanium (SATi), and evaluated the biological response of the materials in vitro. The surfaces of STi, SATi, calcium carbonate coated STi (CC-STi) and calcium carbonate coated SATi (CC-SATi) were characterized for surface roughness, contact angles, surface morphology and surface chemistry. The morphology of MG63 cells cultured on the surfaces was observed by SEM and Immuno-fluorescence staining. Cell attachment/proliferation was assessed by MTT assay, and cell differentiation was evaluated by alkaline phosphatase (ALP) activity. MG63 was found to attach favorably to calcium carbonate crystals with longer cytoplasmic extensions on CC-STi and CC-SATi, resulting in lower cell proliferation but higher ALP activity when compared to STi and SATi respectively. Moreover, CC-SATi is more favorable than CC-STi in terms of biological response. In conclusion, the calcium carbonate coatings on titanium were supposed to improve the osteointegration process and stimulate osteoblast differentiation, especially in early stage. And this method could possibly be a feasible alternative option for future clinical application. Highlights: {yields} Calcium carbonate coatings were prepared on titanium substrates. {yields} The coating process is simple and cost-effective. {yields} Calcium carbonate coating could induce differentiation toward an osteoblastic phenotype. {yields} Calcium carbonate coating could enhance the osteointegration process especially in early stage.

Decreased bacterial growth on titanium nanoscale topographies created by ion beam assisted evaporation

Directory of Open Access Journals (Sweden)

Stolzoff M

2017-02-01

Full Text Available Michelle Stolzoff,1 Jason E Burns,2 Arash Aslani,2 Eric J Tobin,2 Congtin Nguyen,1 Nicholas De La Torre,3 Negar H Golshan,3 Katherine S Ziemer,3 Thomas J Webster1,3,4 1Department of Bioengineering, Northeastern University, Boston, 2N2 Biomedical, Bedford, MA, 3Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 4Center of Excellence for Advanced Materials Research, University of King Abdulaziz, Jeddah, Saudi Arabia Abstract: Titanium is one of the most widely used materials for orthopedic implants, yet it has exhibited significant complications in the short and long term, largely resulting from poor cell–material interactions. Among these many modes of failure, bacterial infection at the site of implantation has become a greater concern with the rise of antibiotic-resistant bacteria. Nanostructured surfaces have been found to prevent bacterial colonization on many surfaces, including nanotextured titanium. In many cases, specific nanoscale roughness values and resulting surface energies have been considered to be “bactericidal”; here, we explore the use of ion beam evaporation as a novel technique to create nanoscale topographical features that can reduce bacterial density. Specifically, we investigated the relationship between the roughness and titanium nanofeature shapes and sizes, in which smaller, more regularly spaced nanofeatures (specifically 40–50 nm tall peaks spaced ~0.25 µm apart were found to have more effect than surfaces with high roughness values alone. Keywords: titanium, nanostructures, bacteria, bone ingrowth, surface roughness, IBAD 

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

Science.gov (United States)

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

2014-07-01

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

Osseointegration of titanium, titanium alloy and zirconia dental implants: current knowledge and open questions.

Science.gov (United States)

Bosshardt, Dieter D; Chappuis, Vivianne; Buser, Daniel

2017-02-01

Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel-fibered and lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone-implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro-rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid-etching may currently be regarded as the gold standard technique to create micro-rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium-zirconium implants in both animals and humans. Surface modifications of zirconia and alumina-toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone-to-implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well-documented implant systems with micro-rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long-term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri-implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm-induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone

Titanium implants with modified surfaces: Meta-analysis of in vivo osteointegration

Energy Technology Data Exchange (ETDEWEB)

Gasik, Michael, E-mail: michael.gasik@aalto.fi [Aalto University Foundation, School of Chemical Technology, P.O. Box 16200, FIN-00076 AALTO (Finland); Braem, Annabel [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium); Chaudhari, Amol; Duyck, Joke [Department of Prosthetic Dentistry, BIOMAT Research Cluster, KU Leuven, Kapucijnenvoer 7a, B-3000 Leuven (Belgium); Vleugels, Jozef [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium)

2015-04-01

Titanium-based implants are widely used in modern clinical practice, but their “optimal” properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4 weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests. - Highlights: • Various titanium specimens were studied in vivo on osteointegration vs their properties. • Non-porous implants had a better performance when coated with bioactive glass. • Porous implants have shown the best results for hydrothermally treated specimens. • Good correlation was found with the previous in vitro tests. • New analysis of the in vivo data has shown benefits to assess biomaterials performance.

Titanium implants with modified surfaces: Meta-analysis of in vivo osteointegration

International Nuclear Information System (INIS)

Gasik, Michael; Braem, Annabel; Chaudhari, Amol; Duyck, Joke; Vleugels, Jozef

2015-01-01

Titanium-based implants are widely used in modern clinical practice, but their “optimal” properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4 weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests. - Highlights: • Various titanium specimens were studied in vivo on osteointegration vs their properties. • Non-porous implants had a better performance when coated with bioactive glass. • Porous implants have shown the best results for hydrothermally treated specimens. • Good correlation was found with the previous in vitro tests. • New analysis of the in vivo data has shown benefits to assess biomaterials performance

Modelling of surface evolution of rough surface on divertor target in fusion devices

International Nuclear Information System (INIS)

Dai, Shuyu; Liu, Shengguang; Sun, Jizhong; Kirschner, A.; Kawamura, G.; Tskhakaya, D.; Ding, Rui; Luo, Guangnan; Wang, Dezhen

2015-01-01

Highlights: • We study the surface evolution of rough surface on divertor target in fusion devices. • The effects of gyration motion and E × B drift affect 3D angular distribution. • A larger magnetic field angle leads to a reduced net eroded areal density. • The rough surface evolution affects the physical sputtering yield. - Abstract: The 3D Monte-Carlo code SURO has been used to study the surface evolution of rough surface on the divertor target in fusion devices. The edge plasma at divertor region is modelled by the SDPIC code and used as input data for SURO. Coupled with SDPIC, SURO can perform more sophisticated simulations to calculate the local angle and surface evolution of rough surface. The simulation results show that the incident direction of magnetic field, gyration and E × B force has a significant impact on 3D angular distribution of background plasma and accordingly on the erosion of rough surface. The net eroded areal density of rough surface is studied by varying the magnetic field angle with surface normal. The evolution of the microscopic morphology of rough surface can lead to a significant change in the physical sputtering yield

Tribological investigations of perfluoroalkylsilanes monolayers deposited on titanium surface

International Nuclear Information System (INIS)

Cichomski, Michał

2012-01-01

Therefore the present work reports a systematic study of titanium modification by fluoroalkylsilanes and surface characterization from the tribological point of view. The vapor phase deposition method was used to modify titanium surfaces by fluoroalkylsilanes and the influence of the used modifier on the tribological properties is presented. The modification procedure efficiency, surface structure and morphology were characterized by secondary ion mass spectrometry, infrared spectroscopy and atomic force microscopy. The effectiveness of modification of the titanium surface was monitored by the measurement of the wetting contact angle and the surface free energy. The increase of surface hydrophobicity was observed upon the modification by increasing the wetting contact angle and reducing the surface free energy. The tribological performance of various perfluoroalkylsilanes films on the titanium surface was investigated in mili- and nano-newton load ranges. Dependence of the adhesive force and coefficient of friction values obtained in nano- and micro-scale on fluoroalkyl chain length was observed. Nano- and micro-tribological measurements show that titanium modified by fluoroalkylsilanes has lower adhesion and coefficient of friction than unmodified one. The investigation also indicates a decrease of the friction coefficient with increasing fluoric alkyl chain length. It was found that the titanium modified by fluoroalkylsilanes with longer alkyl chains is a prime candidate for practical use as a lubricant in biomedical and electronic applications. -- Highlights: ► Titanium surface modification by perfluoroalkylsilanes was investigated. ► The effectiveness of modification was monitored by the surface free energy. ► The modification procedure correctness was characterized by ToF-SIMS, AFM, FT-IR measurements. ► The tribological performance of modified titanium in differed scale was studied.

Effect of bleaching agents and soft drink on titanium surface topography.

Science.gov (United States)

Faverani, Leonardo P; Barão, Valentim A R; Ramalho-Ferreira, Gabriel; Ferreira, Mayara B; Garcia-Júnior, Idelmo R; Assunção, Wirley G

2014-01-01

The effects of carbamide peroxide, hydrogen peroxide and cola soft drink on the topographic modifications of commercially-pure titanium (CP-Ti) and Ti-6Al-4V were investigated. Ti discs were divided into 18 groups (n = 4) based on the solution treatment and Ti type. Specimens were immersed in 3 mL of each solution for 4 h per day (for the remaining 20 h, discs were left dry or immersed in artificial saliva) for 15 days. For control, specimens were immersed in only artificial saliva. Ti surfaces were examined using scanning electron (SEM) and atomic force (AFM) microscopes and their surface roughness (in µm) and surface chemical modifications were investigated. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Groups immersed in 35% hydrogen peroxide showed the highest roughness (Ra) (171.65 ± 4.04 for CP-Ti and 145.91 ± 14.71 for Ti-6Al-4V) (p  0.05). SEM and AFM revealed dramatic changes in the specimens surfaces immersed in the 35% hydrogen peroxide, mainly for CP-Ti. No detectable chemical modifications on the Ti surface were observed. Bleaching agents promoted significant changes in Ti topography, which could affect the longevity of implants treatments. Copyright © 2013 Wiley Periodicals, Inc.

Incorporating Skew into RMS Surface Roughness Probability Distribution

Science.gov (United States)

Stahl, Mark T.; Stahl, H. Philip.

2013-01-01

The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.

Surface-treated commercially pure titanium for biomedical applications: Electrochemical, structural, mechanical and chemical characterizations

International Nuclear Information System (INIS)

Ogawa, Erika S.; Matos, Adaias O.; Beline, Thamara; Marques, Isabella S.V.; Sukotjo, Cortino; Mathew, Mathew T.; Rangel, Elidiane C.; Cruz, Nilson C.; Mesquita, Marcelo F.; Consani, Rafael X.

2016-01-01

Modified surfaces have improved the biological performance and biomechanical fixation of dental implants compared to machined (polished) surfaces. However, there is a lack of knowledge about the surface properties of titanium (Ti) as a function of different surface treatment. This study investigated the role of surface treatments on the electrochemical, structural, mechanical and chemical properties of commercial pure titanium (cp-Ti) under different electrolytes. Cp-Ti discs were divided into 6 groups (n = 5): machined (M—control); etched with HCl + H_2O_2 (Cl), H_2SO_4 + H_2O_2 (S); sandblasted with Al_2O_3 (Sb), Al_2O_3 followed by HCl + H_2O_2 (SbCl), and Al_2O_3 followed by H_2SO_4 + H_2O_2 (SbS). Electrochemical tests were conducted in artificial saliva (pHs 3; 6.5 and 9) and simulated body fluid (SBF—pH 7.4). All surfaces were characterized before and after corrosion tests using atomic force microscopy, scanning electron microscopy, energy dispersive microscopy, X-ray diffraction, surface roughness, Vickers microhardness and surface free energy. The results indicated that Cl group exhibited the highest polarization resistance (R_p) and the lowest capacitance (Q) and corrosion current density (I_c_o_r_r) values. Reduced corrosion stability was noted for the sandblasted groups. Acidic artificial saliva decreased the R_p values of cp-Ti surfaces and produced the highest I_c_o_r_r values. Also, the surface treatment and corrosion process influenced the surface roughness, Vickers microhardness and surface free energy. Based on these results, it can be concluded that acid-etching treatment improved the electrochemical stability of cp-Ti and all treated surfaces behaved negatively in acidic artificial saliva. - Highlights: • Characterization of surface treatment for biomedical implants was investigated. • Sandblasting reduced the corrosion stability of cp-Ti. • Acid etching is a promising dental implants surface treatment.

Surface-treated commercially pure titanium for biomedical applications: Electrochemical, structural, mechanical and chemical characterizations

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Erika S.; Matos, Adaias O.; Beline, Thamara [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br—Institute of Biomaterials, Tribocorrosion and Nanomedicine—Brazilian Branch (Brazil); Marques, Isabella S.V. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); Sukotjo, Cortino [Department of Restorative Dentistry, University of Illinois at Chicago, College of Dentistry, 801 S Paulina, Chicago, IL, USA, 60612 (United States); IBTN—Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Mathew, Mathew T. [IBTN—Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Department of Biomedical Sciences, University of Illinois, College of Medicine at Rockford, 1601 Parkview Avenue, Rockford, IL, USA, 61107 (United States); Rangel, Elidiane C.; Cruz, Nilson C. [IBTN/Br—Institute of Biomaterials, Tribocorrosion and Nanomedicine—Brazilian Branch (Brazil); Laboratory of Technological Plasmas, Engineering College, Univ Estadual Paulista (UNESP), Av Três de Março, 511, Sorocaba, São Paulo 18087-180 (Brazil); Mesquita, Marcelo F.; Consani, Rafael X. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); and others

2016-08-01

Modified surfaces have improved the biological performance and biomechanical fixation of dental implants compared to machined (polished) surfaces. However, there is a lack of knowledge about the surface properties of titanium (Ti) as a function of different surface treatment. This study investigated the role of surface treatments on the electrochemical, structural, mechanical and chemical properties of commercial pure titanium (cp-Ti) under different electrolytes. Cp-Ti discs were divided into 6 groups (n = 5): machined (M—control); etched with HCl + H{sub 2}O{sub 2} (Cl), H{sub 2}SO{sub 4} + H{sub 2}O{sub 2} (S); sandblasted with Al{sub 2}O{sub 3} (Sb), Al{sub 2}O{sub 3} followed by HCl + H{sub 2}O{sub 2} (SbCl), and Al{sub 2}O{sub 3} followed by H{sub 2}SO{sub 4} + H{sub 2}O{sub 2} (SbS). Electrochemical tests were conducted in artificial saliva (pHs 3; 6.5 and 9) and simulated body fluid (SBF—pH 7.4). All surfaces were characterized before and after corrosion tests using atomic force microscopy, scanning electron microscopy, energy dispersive microscopy, X-ray diffraction, surface roughness, Vickers microhardness and surface free energy. The results indicated that Cl group exhibited the highest polarization resistance (R{sub p}) and the lowest capacitance (Q) and corrosion current density (I{sub corr}) values. Reduced corrosion stability was noted for the sandblasted groups. Acidic artificial saliva decreased the R{sub p} values of cp-Ti surfaces and produced the highest I{sub corr} values. Also, the surface treatment and corrosion process influenced the surface roughness, Vickers microhardness and surface free energy. Based on these results, it can be concluded that acid-etching treatment improved the electrochemical stability of cp-Ti and all treated surfaces behaved negatively in acidic artificial saliva. - Highlights: • Characterization of surface treatment for biomedical implants was investigated. • Sandblasting reduced the corrosion stability of cp

Research progress on laser surface modification of titanium alloys

International Nuclear Information System (INIS)

Tian, Y.S.; Chen, C.Z.; Li, S.T.; Huo, Q.H.

2005-01-01

Recent developments on laser surface modification of titanium and its alloys are reviewed. Due to the intrinsic properties of high coherence and directionality, laser beam can be focus onto metallic surface to perform a broad range of treatments such as remelting, alloying and cladding, which are used to improve the wear and corrosion resistance of titanium alloys. In addition, the fabrication of bioactive films on the surface of titanium alloys to improve their biocompatibility can be performed by the method of laser ablation deposition. The effect of some laser processing parameters on the resulting surface properties of titanium alloys is discussed. The problems to be solved and the prospects in the field of laser modification of titanium and its alloys are elucidated

Adhesion of osteoblasts to a nanorough titanium implant surface

Directory of Open Access Journals (Sweden)

Gongadze E

2011-08-01

Full Text Available Ekaterina Gongadze1, Doron Kabaso2, Sebastian Bauer3, Tomaž Slivnik2, Patrik Schmuki3, Ursula van Rienen1, Aleš Iglič21Institute of General Electrical Engineering, University of Rostock, Rostock, Germany; 2Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; 3Department of Materials Science, Friedrich-Alexander University of Erlangen-Nurenberg, Erlangen, GermanyAbstract: This work considers the adhesion of cells to a nanorough titanium implant surface with sharp edges. The basic assumption was that the attraction between the negatively charged titanium surface and a negatively charged osteoblast is mediated by charged proteins with a distinctive quadrupolar internal charge distribution. Similarly, cation-mediated attraction between fibronectin molecules and the titanium surface is expected to be more efficient for a high surface charge density, resulting in facilitated integrin mediated osteoblast adhesion. We suggest that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest. It is therefore plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblasts.Keywords: osteoblasts, nanostructures, adhesion, titanium implants, osteointegration

High-pressure coolant effect on the surface integrity of machining titanium alloy Ti-6Al-4V: a review

Science.gov (United States)

Liu, Wentao; Liu, Zhanqiang

2018-03-01

Machinability improvement of titanium alloy Ti-6Al-4V is a challenging work in academic and industrial applications owing to its low thermal conductivity, low elasticity modulus and high chemical affinity at high temperatures. Surface integrity of titanium alloys Ti-6Al-4V is prominent in estimating the quality of machined components. The surface topography (surface defects and surface roughness) and the residual stress induced by machining Ti-6Al-4V occupy pivotal roles for the sustainability of Ti-6Al-4V components. High-pressure coolant (HPC) is a potential choice in meeting the requirements for the manufacture and application of Ti-6Al-4V. This paper reviews the progress towards the improvements of Ti-6Al4V surface integrity under HPC. Various researches of surface integrity characteristics have been reported. In particularly, surface roughness, surface defects, residual stress as well as work hardening are investigated in order to evaluate the machined surface qualities. Several coolant parameters (including coolant type, coolant pressure and the injection position) deserve investigating to provide the guidance for a satisfied machined surface. The review also provides a clear roadmap for applications of HPC in machining Ti-6Al4V. Experimental studies and analysis are reviewed to better understand the surface integrity under HPC machining process. A distinct discussion has been presented regarding the limitations and highlights of the prospective for machining Ti-6Al4V under HPC.

Factors influencing surface roughness of polyimide film

International Nuclear Information System (INIS)

Yao Hong; Zhang Zhanwen; Huang Yong; Li Bo; Li Sai

2011-01-01

The polyimide (PI) films of pyromellitic dianhydride-oxydiamiline (PMDA-ODA) were fabricated using vapor deposition polymerization (VDP) method under high vacuum pressure of 10-4 Pa level. The influence of equipment, substrate temperature, the process of heating and deposition ratio of monomers on the surface roughness of the PI films was investigated. The surface topography of films was measured by interferometer microscopy and scanning electron microscopy(SEM), and the surface roughness was probed with atomic force microscopy(AFM). The results show that consecutive films can be formed when the distance from steering flow pipe to substrate is 74 cm. The surface roughnesses are 291.2 nm and 61.9 nm respectively for one-step heating process and multi-step heating process, and using fine mesh can effectively avoid the splash of materials. The surface roughness can be 3.3 nm when the deposition rate ratio of PMDA to ODA is 0.9:1, and keeping the temperature of substrate around 30 degree C is advantageous to form a film with planar micro-surface topography. (authors)

Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis.

Science.gov (United States)

Kang, He-Kyong; Chu, Tien-Min; Dechow, Paul; Stewart, Kelton; Kyung, Hee-Moon; Liu, Sean Shih-Yao

2016-04-01

This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P titanium alloy MSIs. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Bioactive treatment promotes osteoblast differentiation on titanium materials fabricated by selective laser melting technology.

Science.gov (United States)

Tsukanaka, Masako; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Sasaki, Kiyoyuki; Matsuda, Shuichi

2016-01-01

Selective laser melting (SLM) technology is useful for the fabrication of porous titanium implants with complex shapes and structures. The materials fabricated by SLM characteristically have a very rough surface (average surface roughness, Ra=24.58 µm). In this study, we evaluated morphologically and biochemically the specific effects of this very rough surface and the additional effects of a bioactive treatment on osteoblast proliferation and differentiation. Flat-rolled titanium materials (Ra=1.02 µm) were used as the controls. On the treated materials fabricated by SLM, we observed enhanced osteoblast differentiation compared with the flat-rolled materials and the untreated materials fabricated by SLM. No significant differences were observed between the flat-rolled materials and the untreated materials fabricated by SLM in their effects on osteoblast differentiation. We concluded that the very rough surface fabricated by SLM had to undergo a bioactive treatment to obtain a positive effect on osteoblast differentiation.

Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

Energy Technology Data Exchange (ETDEWEB)

Cruz, Marcos Antônio E.; Ruiz, Gilia C.M. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Faria, Amanda N. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Departamento de Bioquímica e Imunologia-Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Ramos, Ana P., E-mail: anapr@ffclrp.usp.br [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil)

2016-05-01

Graphical abstract: - Highlights: • CaCO{sub 3} continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO{sub 3} particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO{sub 3} deposited as thin films for this propose is unknown. Here, we report the growth of CaCO{sub 3} continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca{sup 2+}, exposed to CO{sub 2} (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO{sub 3} film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ{sub s}) were accessed. The presence of HAp increased the wettability and γ{sub s} of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO{sub 3} thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

International Nuclear Information System (INIS)

Cruz, Marcos Antônio E.; Ruiz, Gilia C.M.; Faria, Amanda N.; Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro; Ramos, Ana P.

2016-01-01

Graphical abstract: - Highlights: • CaCO 3 continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO 3 particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO 3 deposited as thin films for this propose is unknown. Here, we report the growth of CaCO 3 continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca 2+ , exposed to CO 2 (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO 3 film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ s ) were accessed. The presence of HAp increased the wettability and γ s of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO 3 thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

Antiseptics and microcosm biofilm formation on titanium surfaces

Directory of Open Access Journals (Sweden)

Georgia VERARDI

2016-01-01

Full Text Available Abstract Oral rehabilitation with osseointegrated implants is a way to restore esthetics and masticatory function in edentulous patients, but bacterial colonization around the implants may lead to mucositis or peri-implantitis and consequent implant loss. Peri-implantitis is the main complication of oral rehabilitation with dental implants and, therefore, it is necessary to take into account the potential effects of antiseptics such as chlorhexidine (CHX, chloramine T (CHT, triclosan (TRI, and essential oils (EO on bacterial adhesion and on biofilm formation. To assess the action of these substances, we used the microcosm technique, in which the oral environment and periodontal conditions are simulated in vitro on titanium discs with different surface treatments (smooth surface - SS, acid-etched smooth surface - AESS, sand-blasted surface - SBS, and sand-blasted and acid-etched surface - SBAES. Roughness measurements yielded the following results: SS: 0.47 µm, AESS: 0.43 µm, SB: 0.79 µm, and SBAES: 0.72 µm. There was statistical difference only between SBS and AESS. There was no statistical difference among antiseptic treatments. However, EO and CHT showed lower bacterial counts compared with the saline solution treatment (control group. Thus, the current gold standard (CHX did not outperform CHT and EO, which were efficient in reducing the biofilm biomass compared with saline solution.

Rough Surface Contact

Directory of Open Access Journals (Sweden)

T Nguyen

2017-06-01

Full Text Available This paper studies the contact of general rough curved surfaces having nearly identical geometries, assuming the contact at each differential area obeys the model proposed by Greenwood and Williamson. In order to account for the most general gross geometry, principles of differential geometry of surface are applied. This method while requires more rigorous mathematical manipulations, the fact that it preserves the original surface geometries thus makes the modeling procedure much more intuitive. For subsequent use, differential geometry of axis-symmetric surface is considered instead of general surface (although this “general case” can be done as well in Chapter 3.1. The final formulas for contact area, load, and frictional torque are derived in Chapter 3.2.

Osteoblastic response to pectin nanocoating on titanium surfaces

Energy Technology Data Exchange (ETDEWEB)

Gurzawska, Katarzyna, E-mail: kagu@sund.ku.dk [Research Center for Ageing and Osteoporosis, Departments of Medicine and Diagnostics, Copenhagen University Hospital Glostrup, Ndr. Ringvej 57, 2600 Glostrup (Denmark); Institute of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Allé 20, 2200 Copenhagen N (Denmark); Svava, Rikke [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Copenhagen Center for Glycomics, Institute for Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N (Denmark); Yihua, Yu; Haugshøj, Kenneth Brian [Microtechnology and Surface Analysis, Danish Technological Institute, Gregersensvej 8, 2630 Taastrup (Denmark); Dirscherl, Kai [Dansk Fundamental Metrologi A/S, Matematiktorvet 307, 2800 Lyngby (Denmark); Levery, Steven B. [Copenhagen Center for Glycomics, Institute for Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N (Denmark); Byg, Inge [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Damager, Iben [Novozymes A/S, Krogshoejvej 36, 2880 Bagsvaerd (Denmark); Nielsen, Martin W. [Department of Systems Biology, Technical University of Denmark, Matematiktorvet, Building 301, Kgs. Lyngby DK-2800 (Denmark); Jørgensen, Bodil [Department of Plant Environment Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Jørgensen, Niklas Rye [Research Center for Ageing and Osteoporosis, Departments of Medicine and Diagnostics, Copenhagen University Hospital Glostrup, Ndr. Ringvej 57, 2600 Glostrup (Denmark); and others

2014-10-01

Osseointegration of titanium implants can be improved by organic and inorganic nanocoating of the surface. The aim of our study was to evaluate the effect of organic nanocoating of titanium surface with unmodified and modified pectin Rhamnogalacturonan-Is (RG-Is) isolated from potato and apple with respect to surface properties and osteogenic response in osteoblastic cells. Nanocoatings on titanium surfaces were evaluated by scanning electron microscopy, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of coated RG-Is on cell adhesion, cell viability, bone matrix formation and mineralization was tested using SaOS-2 cells. Nanocoating with pectin RG-Is affected surface properties and in consequence changed the environment for cellular response. The cells cultured on surfaces coated with RG-Is from potato with high content of linear 1.4-linked galactose produced higher level of mineralized matrix compared with control surfaces and surfaces coated with RG-I with low content of linear 1.4-linked galactose. The study showed that the pectin RG-Is nanocoating not only changed chemical and physical titanium surface properties, but also specific coating with RG-Is containing high amount of galactan increased mineralized matrix formation of osteoblastic cells in vitro. - Highlights: • Surface nanocoating with plant-derived Rhamnogalacturonan-I (RG-I) is proposed. • Titanium surface became more hydrophilic after RG-Is nanocoating. • RG-Is with high galactose content resulted in high level of mineralized matrix. • RG-I is a new candidate for improvement of bone healing and osseointegration.

Surface roughness effects on turbulent Couette flow

Science.gov (United States)

Lee, Young Mo; Lee, Jae Hwa

2017-11-01

Direct numerical simulation of a turbulent Couette flow with two-dimensional (2-D) rod roughness is performed to examine the effects of the surface roughness. The Reynolds number based on the channel centerline laminar velocity (Uco) and channel half height (h) is Re =7200. The 2-D rods are periodically arranged with a streamwise pitch of λ = 8 k on the bottom wall, and the roughness height is k = 0.12 h. It is shown that the wall-normal extent for the logarithmic layer is significantly shortened in the rough-wall turbulent Couette flow, compared to a turbulent Couette flow with smooth wall. Although the Reynolds stresses are increased in a turbulent channel flow with surface roughness in the outer layer due to large-scale ejection motions produced by the 2-D rods, those of the rough-wall Couette flow are decreased. Isosurfaces of the u-structures averaged in time suggest that the decrease of the turbulent activity near the centerline is associated with weakened large-scale counter-rotating roll modes by the surface roughness. This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1A09000537) and the Ministry of Science, ICT & Future Planning (NRF-2017R1A5A1015311).

Surface Modification of Titanium Using Anodization to Enhance Antimicrobial Properties and Osseointegration

Science.gov (United States)

Jain, Sakshi

Titanium and its alloys are frequently used in dental and orthopedic implants because they have good mechanical strength, chemical stability and biocompatibility. These properties can be further improved by surface treatments such as anodization that are able to grow thicker and produce crystalline oxide layers with controlled morphological and physico-chemical properties. Both anatase (A) and rutile (R) crystalline phases of titanium oxide have been shown to promote bioactivity and antimicrobial effects. In a previous study in our laboratories, four electrolyte mixtures were optimized to produce anodized layers on commercially pure titanium consisting of specific anatase and rutile oxide ratios at an endpoint forming voltage of 180 V. In the present study, changes that occurred in the anodized layers with increasing forming voltage including crystallinity, thickness, surface morphology, surface roughness, surface chemistry, fractal dimension, shear strength, and corrosion resistance were determined for each of these electrolytes. The results showed the crystallinity, thickness, surface pore sizes, and surface roughness increased with increasing forming voltage. Incorporation of phosphorus into the anodized layers was shown in phosphoric acid containing electrolytes at higher forming voltages. Decreases in corrosion resistance were also shown at higher forming voltages in each electrolyte due to increased pore interconnectivity within the anodized layers. In addition, the apatite inducing ability of anodized layers in SBF was examined for selected forming voltages in each electrolyte. Anodization in phosphoric acid containing electrolytes was shown to be more favorable for apatite formation. The streptococcal and MRSA bacterial attachment before and after UV treatments was determined for selected forming voltages in each electrolyte. Additionally, the killing efficacy after 10-minute pre-irradiation with UVA or UVC treatments was determined. UVA treatments showed

Modeling Surface Roughness to Estimate Surface Moisture Using Radarsat-2 Quad Polarimetric SAR Data

Science.gov (United States)

Nurtyawan, R.; Saepuloh, A.; Budiharto, A.; Wikantika, K.

2016-08-01

Microwave backscattering from the earth's surface depends on several parameters such as surface roughness and dielectric constant of surface materials. The two parameters related to water content and porosity are crucial for estimating soil moisture. The soil moisture is an important parameter for ecological study and also a factor to maintain energy balance of land surface and atmosphere. Direct roughness measurements to a large area require extra time and cost. Heterogeneity roughness scale for some applications such as hydrology, climate, and ecology is a problem which could lead to inaccuracies of modeling. In this study, we modeled surface roughness using Radasat-2 quad Polarimetric Synthetic Aperture Radar (PolSAR) data. The statistical approaches to field roughness measurements were used to generate an appropriate roughness model. This modeling uses a physical SAR approach to predicts radar backscattering coefficient in the parameter of radar configuration (wavelength, polarization, and incidence angle) and soil parameters (surface roughness and dielectric constant). Surface roughness value is calculated using a modified Campbell and Shepard model in 1996. The modification was applied by incorporating the backscattering coefficient (σ°) of quad polarization HH, HV and VV. To obtain empirical surface roughness model from SAR backscattering intensity, we used forty-five sample points from field roughness measurements. We selected paddy field in Indramayu district, West Java, Indonesia as the study area. This area was selected due to intensive decreasing of rice productivity in the Northern Coast region of West Java. Third degree polynomial is the most suitable data fitting with coefficient of determination R2 and RMSE are about 0.82 and 1.18 cm, respectively. Therefore, this model is used as basis to generate the map of surface roughness.

Effect of cathodic polarization on coating doxycycline on titanium surfaces

Energy Technology Data Exchange (ETDEWEB)

Geißler, Sebastian; Tiainen, Hanna; Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no

2016-06-01

Cathodic polarization has been reported to enhance the ability of titanium based implant materials to interact with biomolecules by forming titanium hydride at the outermost surface layer. Although this hydride layer has recently been suggested to allow the immobilization of the broad spectrum antibiotic doxycycline on titanium surfaces, the involvement of hydride in binding the biomolecule onto titanium remains poorly understood. To gain better understanding of the influence this immobilization process has on titanium surfaces, mirror-polished commercially pure titanium surfaces were cathodically polarized in the presence of doxycycline and the modified surfaces were thoroughly characterized using atomic force microscopy, electron microscopy, secondary ion mass spectrometry, and angle-resolved X-ray spectroscopy. We demonstrated that no hydride was created during the polarization process. Doxycycline was found to be attached to an oxide layer that was modified during the electrochemical process. A bacterial assay using bioluminescent Staphylococcus epidermidis Xen43 showed the ability of the coating to reduce bacterial colonization and planktonic bacterial growth. - Highlights: • Titanium hydride was found not to be involved in immobilization of doxycycline. • Doxycycline coating was strongly bound to a modified surface oxide layer. • Effect of coatings tested using a dynamic bacteria assay based on bioluminescence. • Topmost layer of adsorbed doxycycline was shown to have strong antibacterial effect.

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Spin Hall effect by surface roughness

KAUST Repository

Zhou, Lingjun

2015-01-08

The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.

Roughness analysis of graphite surfaces of casting elements

Directory of Open Access Journals (Sweden)

M. Wieczorowski

2010-01-01

Full Text Available In the paper profilometric measurements of graphite casting elements were described. Basic topics necessary to assess roughness of their surfaces and influence of asperities on various properties related to manufacturing and use were discussed. Stylus profilometer technique of surface irregularities measurements including its limits resulting from pickup geometry and its contact with measured object were ana-lyzed. Working principle of tactile profilometer and phenomena taking place during movement of a probe on a measured surface were shown. One of the important aspects is a flight phenomenon, which means movement of a pickup without contact with a surface during inspection resulting from too high scanning speed. results of comparison research for graphite elements of new and used mould and pin composing a set were presented. Using some surface roughness, waviness and primary profile parameters (arithmetical mean of roughness profile heights Ra, biggest roughness profile height Rz, maximum primary profile height Pt as well as maximum waviness profile height Wt a possibility of using surface asperities parameters as a measure of wear of chill graphite elements was proved. The most often applied parameter is Ra, but with a help of parameters from W and P family it was shown, that big changes occur not only for roughness but also for other components of surface irregularities.

Surface Forces Apparatus measurements of interactions between rough and reactive calcite surfaces.

Science.gov (United States)

Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon Einar; Nilsen, Ola; Røyne, Anja

2018-05-28

Nm-range forces acting between calcite surfaces in water affect macroscopic properties of carbonate rocks and calcite-based granular materials, and are significantly influenced by calcite surface recrystallization. We suggest that the repulsive mechanical effects related to nm-scale surface recrystallization of calcite in water could be partially responsible for the observed decrease of cohesion in calcitic rocks saturated with water. Using the Surface Forces Apparatus (SFA), we simultaneously followed the calcite reactivity and measured the forces in water in two surface configurations: between two rough calcite surfaces (CC), or between rough calcite and a smooth mica surface (CM). We used nm-scale rough, polycrystalline calcite films prepared by Atomic Layer Deposition (ALD). We measured only repulsive forces in CC in CaCO 3 -saturated water, which was related to roughness and possibly to repulsive hydration effects. Adhesive or repulsive forces were measured in CM in CaCO 3 -saturated water depending on calcite roughness, and the adhesion was likely enhanced by electrostatic effects. The pull-off adhesive force in CM became stronger with time and this increase was correlated with a decrease of roughness at contacts, which parameter could be estimated from the measured force-distance curves. That suggested a progressive increase of real contact areas between the surfaces, caused by gradual pressure-driven deformation of calcite surface asperities during repeated loading-unloading cycles. Reactivity of calcite was affected by mass transport across nm to µm-thick gaps between the surfaces. Major roughening was observed only for the smoothest calcite films, where gaps between two opposing surfaces were nm-thick over µm-sized areas, and led to force of crystallization that could overcome confining pressures of the order of MPa. Any substantial roughening of calcite caused a significant increase of the repulsive mechanical force contribution.

Osseointegration improvement by plasma electrolytic oxidation of modified titanium alloys surfaces.

Science.gov (United States)

Echeverry-Rendón, Mónica; Galvis, Oscar; Quintero Giraldo, David; Pavón, Juan; López-Lacomba, José Luis; Jiménez-Piqué, Emilio; Anglada, Marc; Robledo, Sara M; Castaño, Juan G; Echeverría, Félix

2015-02-01

Titanium (Ti) is a material frequently used in orthopedic applications, due to its good mechanical properties and high corrosion resistance. However, formation of a non-adherent fibrous tissue between material and bone drastically could affect the osseointegration process and, therefore, the mechanical stability of the implant. Modifications of topography and configuration of the tissue/material interface is one of the mechanisms to improve that process by manipulating parameters such as morphology and roughness. There are different techniques that can be used to modify the titanium surface; plasma electrolytic oxidation (PEO) is one of those alternatives, which consists of obtaining porous anodic coatings by controlling parameters such as voltage, current, anodizing solution and time of the reaction. From all of the above factors, and based on previous studies that demonstrated that bone cells sense substrates features to grow new tissue, in this work commercially pure Ti (c.p Ti) and Ti6Al4V alloy samples were modified at their surface by PEO in different anodizing solutions composed of H2SO4 and H3PO4 mixtures. Treated surfaces were characterized and used as platforms to grow osteoblasts; subsequently, cell behavior parameters like adhesion, proliferation and differentiation were also studied. Although the results showed no significant differences in proliferation, differentiation and cell biological activity, overall results showed an important influence of topography of the modified surfaces compared with polished untreated surfaces. Finally, this study offers an alternative protocol to modify surfaces of Ti and their alloys in a controlled and reproducible way in which biocompatibility of the material is not compromised and osseointegration would be improved.

Why do rough surfaces appear glossy?

Science.gov (United States)

Qi, Lin; Chantler, Mike J; Siebert, J Paul; Dong, Junyu

2014-05-01

The majority of work on the perception of gloss has been performed using smooth surfaces (e.g., spheres). Previous studies that have employed more complex surfaces reported that increasing mesoscale roughness increases perceived gloss [Psychol. Sci.19, 196 (2008), J. Vis.10(9), 13 (2010), Curr. Biol.22, 1909 (2012)]. We show that the use of realistic rendering conditions is important and that, in contrast to [Psychol. Sci.19, 196 (2008), J. Vis.10(9), 13 (2010)], after a certain point increasing roughness further actually reduces glossiness. We investigate five image statistics of estimated highlights and show that for our stimuli, one in particular, which we term "percentage of highlight area," is highly correlated with perceived gloss. We investigate a simple model that explains the unimodal, nonmonotonic relationship between mesoscale roughness and percentage highlight area.

Surface Roughness of the Moon Derived from Multi-frequency Radar Data

Science.gov (United States)

Fa, W.

2011-12-01

Surface roughness of the Moon provides important information concerning both significant questions about lunar surface processes and engineering constrains for human outposts and rover trafficabillity. Impact-related phenomena change the morphology and roughness of lunar surface, and therefore surface roughness provides clues to the formation and modification mechanisms of impact craters. Since the Apollo era, lunar surface roughness has been studied using different approaches, such as direct estimation from lunar surface digital topographic relief, and indirect analysis of Earth-based radar echo strengths. Submillimeter scale roughness at Apollo landing sites has been studied by computer stereophotogrammetry analysis of Apollo Lunar Surface Closeup Camera (ALSCC) pictures, whereas roughness at meter to kilometer scale has been studied using laser altimeter data from recent missions. Though these studies shown lunar surface roughness is scale dependent that can be described by fractal statistics, roughness at centimeter scale has not been studied yet. In this study, lunar surface roughnesses at centimeter scale are investigated using Earth-based 70 cm Arecibo radar data and miniature synthetic aperture radar (Mini-SAR) data at S- and X-band (with wavelengths 12.6 cm and 4.12 cm). Both observations and theoretical modeling show that radar echo strengths are mostly dominated by scattering from the surface and shallow buried rocks. Given the different penetration depths of radar waves at these frequencies (< 30 m for 70 cm wavelength, < 3 m at S-band, and < 1 m at X-band), radar echo strengths at S- and X-band will yield surface roughness directly, whereas radar echo at 70-cm will give an upper limit of lunar surface roughness. The integral equation method is used to model radar scattering from the rough lunar surface, and dielectric constant of regolith and surface roughness are two dominate factors. The complex dielectric constant of regolith is first estimated

Characterization polyethylene terephthalate nanocomposites mixing with nano-silica and titanium oxide

Directory of Open Access Journals (Sweden)

Rusu Mircea A.

2017-01-01

Full Text Available Polyethylene terephthalate (PET based nanocomposites containing nano-silica (Aerosil (Degusa and titanium oxide (TiO2 (Merk were prepared by melt compounding. Influence of nano-silica and titanium oxide on properties of the resulting nanocomposites was investigated by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR and atomic force microscopy (AFM. The possible interaction between nano-silica and titanium oxide particles with PET functional groups at bulk and surface was elucidated by transmission of FTIR-ATR spectroscopy. AFM studies of the resulting nanocomposites showed an increased surface roughness compared to pure PET. SEM images illustrated that nano-silica particles have tendency to migrate to the surface of the PET matrix much more than titanium oxide powder.

Electron beam cladding of titanium on stainless steel plate

International Nuclear Information System (INIS)

Tomie, Michio; Abe, Nobuyuki; Yamada, Masanori; Noguchi, Shuichi.

1990-01-01

Fundamental characteristics of electron beam cladding was investigated. Titanium foil of 0.2mm thickness was cladded on stainless steel plate of 3mm thickness by scanning electron beam. Surface roughness and cladded layer were analyzed by surface roughness tester, microscope, scanning electron microscope and electron probe micro analyzer. Electron beam conditions were discussed for these fundamental characteristics. It is found that the energy density of the electron beam is one of the most important factor for cladding. (author)

A new fiber optic sensor for inner surface roughness measurement

Science.gov (United States)

Xu, Xiaomei; Liu, Shoubin; Hu, Hong

2009-11-01

In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.

Influence of surface roughness on the corrosion behaviour of magnesium alloy

International Nuclear Information System (INIS)

Walter, R.; Kannan, M. Bobby

2011-01-01

Research highlights: → Surface roughness of AZ91 magnesium alloy plays a critical role in the passivation behaviour of the alloy. → The passivation behaviour of the alloy influences the pitting tendency. → Increase in surface roughness of AZ91 magnesium alloy increases the pitting tendency of the alloy. -- Abstract: In this study, the influence of surface roughness on the passivation and pitting corrosion behaviour of AZ91 magnesium alloy in chloride-containing environment was examined using electrochemical techniques. Potentiodynamic polarisation and electrochemical impedance spectroscopy tests suggested that the passivation behaviour of the alloy was affected by increasing the surface roughness. Consequently, the corrosion current and the pitting tendency of the alloy also increased with increase in the surface roughness. Scanning electron micrographs of 24 h immersion test samples clearly revealed pitting corrosion in the highest surface roughness (Sa 430) alloy, whereas in the lowest surface roughness (Sa 80) alloy no evidence of pitting corrosion was observed. Interestingly, when the passivity of the alloy was disturbed by galvanostatically holding the sample at anodic current for 1 h, the alloy underwent high pitting corrosion irrespective of their surface roughness. Thus the study suggests that the surface roughness plays a critical role in the passivation behaviour of the alloy and hence the pitting tendency.

Guided self-assembly of nanostructured titanium oxide

International Nuclear Information System (INIS)

Wang Baoxiang; Rozynek, Zbigniew; Fossum, Jon Otto; Knudsen, Kenneth D; Yu Yingda

2012-01-01

A series of nanostructured titanium oxide particles were synthesized by a simple wet chemical method and characterized by means of small-angle x-ray scattering (SAXS)/wide-angle x-ray scattering (WAXS), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis, and rheometry. Tetrabutyl titanate (TBT) and ethylene glycol (EG) can be combined to form either TiO x nanowires or smooth nanorods, and the molar ratio of TBT:EG determines which of these is obtained. Therefore, TiO x nanorods with a highly rough surface can be obtained by hydrolysis of TBT with the addition of cetyl-trimethyl-ammonium bromide (CTAB) as surfactant in an EG solution. Furthermore, TiO x nanorods with two sharp ends can be obtained by hydrolysis of TBT with the addition of salt (LiCl) in an EG solution. The AFM results show that the TiO x nanorods with rough surfaces are formed by the self-assembly of TiO x nanospheres. The electrorheological (ER) effect was investigated using a suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic reorganization when submitted to a strong DC electric field and the particles aggregate to form chain-like structures along the direction of applied electric field. Two-dimensional SAXS images from chains of anisotropically shaped particles exhibit a marked asymmetry in the SAXS patterns, reflecting the preferential self-assembly of the particles in the field. The suspension of rough TiO x nanorods shows stronger ER properties than that of the other nanostructured TiO x particles. We find that the particle surface roughness plays an important role in modification of the dielectric properties and in the enhancement of the ER effect. (paper)

Guided self-assembly of nanostructured titanium oxide

Science.gov (United States)

Wang, Baoxiang; Rozynek, Zbigniew; Fossum, Jon Otto; Knudsen, Kenneth D.; Yu, Yingda

2012-02-01

A series of nanostructured titanium oxide particles were synthesized by a simple wet chemical method and characterized by means of small-angle x-ray scattering (SAXS)/wide-angle x-ray scattering (WAXS), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis, and rheometry. Tetrabutyl titanate (TBT) and ethylene glycol (EG) can be combined to form either TiOx nanowires or smooth nanorods, and the molar ratio of TBT:EG determines which of these is obtained. Therefore, TiOx nanorods with a highly rough surface can be obtained by hydrolysis of TBT with the addition of cetyl-trimethyl-ammonium bromide (CTAB) as surfactant in an EG solution. Furthermore, TiOx nanorods with two sharp ends can be obtained by hydrolysis of TBT with the addition of salt (LiCl) in an EG solution. The AFM results show that the TiOx nanorods with rough surfaces are formed by the self-assembly of TiOx nanospheres. The electrorheological (ER) effect was investigated using a suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic reorganization when submitted to a strong DC electric field and the particles aggregate to form chain-like structures along the direction of applied electric field. Two-dimensional SAXS images from chains of anisotropically shaped particles exhibit a marked asymmetry in the SAXS patterns, reflecting the preferential self-assembly of the particles in the field. The suspension of rough TiOx nanorods shows stronger ER properties than that of the other nanostructured TiOx particles. We find that the particle surface roughness plays an important role in modification of the dielectric properties and in the enhancement of the ER effect.

Use of roughness maps in visualisation of surfaces

DEFF Research Database (Denmark)

Seitavuopio, Paulus; Rantanen, Jukka; Yliruusi, Jouko

2005-01-01

monohydrate, theophylline anhydrate, sodium chloride and potassium chloride. The roughness determinations were made by a laser profilometer. The new matrix method gives detailed roughness maps, which are able to show local variations in surface roughness values and provide an illustrative picture...

Repercussion of noni mouthwash on surface characterization of Nickel-Titanium archwire

Directory of Open Access Journals (Sweden)

Dhivya Dilipkumar

2017-01-01

Full Text Available Objective: Maintaining oral hygiene is very important during orthodontic therapy mouthwashes are prescribed as an adjunct to improve patient's oral hygiene. Commercially available mouthwashes e.g. Chlorhexidine, Listerine, fluoride containing mouthwashes have shown to alter the surface characteristics of orthodontic wires. Hence the purpose of the study was to evaluate the effect of Noni mouthwash on surface quality and compositional changes of Nickel Titanium orthodontic wires. Materials and Methods: In this in vitro study pre-formed 0.014 inch NiTi arch wire was used. The study comprised of two samples, one control and one test sample which were 25mm in length. Control sample was stored at room temperature without any manipulation while test sample was immersed in Noni mouthwash solution for 1.5 hours, after which the test specimen was removed from the mouthwash solution and rinsed with distilled water. Both control and test samples were sent for scanning electron microscopy analysis, to qualitatively characterize the topography of the wire surface. Electron dispersion spectrum analysis was done to evaluate the various components of both the wires. Results: No significant difference in the average surface roughness for both wire samples was observed. There was no significant difference seen in the composition of wire after immersion in Noni mouthwash. Conclusion: Noni mouthwash did not have significant influence on the surface roughness or altered the composition of the Ni-Ti wire. Hence Noni mouthwash may be prescribed as a natural, non-destructive prophylactic agent for orthodontic patients.

ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES

Energy Technology Data Exchange (ETDEWEB)

Ribeill, G.; Reece, C.

2008-01-01

Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.

The Role of Titanium Surface Microtopography on Adhesion, Proliferation, Transformation, and Matrix Deposition of Corneal Cells.

Science.gov (United States)

Zhou, Chengxin; Lei, Fengyang; Chodosh, James; Paschalis, Eleftherios I

2016-04-01

Titanium (Ti) is an excellent implantable biomaterial that can be further enhanced by surface topography optimization. Despite numerous data from orthopedics and dentistry, the effect of Ti surface topography on ocular cells is still poorly understood. In light of the recent adaptation of Ti in the Boston Keratoprosthesis artificial cornea, we attempted to perform an extended evaluation of the effect of Ti surface topography on corneal cell adhesion, proliferation, cytotoxicity, transformation, and matrix deposition. Different surface topographies were generated on medical grade Ti-6Al-4V-ELI (extra-low interstitial), with linearly increased roughness (polished to grit blasted). Biological response was evaluated in vitro using human corneal limbal epithelial (HCLE) cells, stromal fibroblasts (HCF), and endothelial cells (HCEnC). None of the Ti surface topographies caused cytotoxicity to any of the three corneal cell types. However, rough Ti surface inhibited HCLE and HCF cell adhesion and proliferation, while HCEnC proliferation was unaffected. Long-term experiments with HCF revealed that rough Ti surface with R(a) (the arithmetic average of the profile height from the mean line) ≥ 1.15 μm suppressed HCF focal adhesion kinase phosphorylation, changed fibroblast morphology, and caused less aligned and reduced deposition of collagen matrix as compared to smooth Ti (R(a) ≤ 0.08 μm). In the presence of transforming growth factor β1 (TGFβ1) stimulation, rough Ti inhibited alpha-smooth muscle actin (α-SMA) expression and collagen deposition, leading to decreased myofibroblast transformation and disorganization of the collagen fibrils as compared to smooth Ti. This study suggests that Ti surface topography regulates corneal cell behavior in a tissue-dependent manner that varies across the corneal strata. Contrary to the accepted paradigm, smooth surface topography can enhance cell adhesion and proliferation and increase matrix deposition by corneal cells.

Influence of surface roughness on the friction property of textured surface

OpenAIRE

Yuankai Zhou; Hua Zhu; Wenqian Zhang; Xue Zuo; Yan Li; Jianhua Yang

2015-01-01

In contrast with dimple textures, surface roughness is a texture at the micro-scale, essentially which will influence the load-bearing capacity of lubricant film. The numerical simulation was carried out to investigate the influence of surface roughness on friction property of textured surface. The lubricant film pressure was obtained using the method of computational fluid dynamics according to geometric model of round dimple, and the renormalization-group k–ε turbulent model was adopted in ...

Armor Plate Surface Roughness Measurements

National Research Council Canada - National Science Library

Stanton, Brian; Coburn, William; Pizzillo, Thomas J

2005-01-01

...., surface texture and coatings) that could become important at high frequency. We measure waviness and roughness of various plates to know the parameter range for smooth aluminum and rolled homogenous armor (RHA...

Numerical analysis of the bucket surface roughness effects in Pelton turbine

International Nuclear Information System (INIS)

Xiao, Y X; Zeng, C J; Zhang, J; Yan, Z G; Wang, Z W

2013-01-01

The internal flow of a Pelton turbine is quite complex. It is difficult to analyse the unsteady free water sheet flow in the rotating bucket owing to the lack of a sound theory. Affected by manufacturing technique and silt abrasion during the operation, the bucket surface roughness of Pelton turbine may be too great, and thereby influence unit performance. To investigate the effect of bucket roughness on Pelton turbine performance, this paper presents the numerical simulation of the interaction between the jet and the bucket in a Pelton turbine. The unsteady three-dimensional numerical simulations were performed with CFX code by using the SST turbulence model coupling the two-phase flow volume of fluid method. Different magnitude orders of bucket surface roughness were analysed and compared. Unsteady numerical results of the free water sheet flow patterns on bucket surface, torque and unit performance for each bucket surface roughness were generated. The total pressure distribution on bucket surface is used to show the free water sheet flow pattern on bucket surface. By comparing the variation of water sheet flow patterns on bucket surface with different roughness, this paper qualitatively analyses how the bucket surface roughness magnitude influences the impeding effect on free water sheet flow. Comparison of the torque variation of different bucket surface roughness highlighted the effect of the bucket surface roughness on the Pelton turbine output capacity. To further investigate the effect of bucket surface roughness on Pelton turbine performance, the relation between the relative efficiency loss rate and bucket surface roughness magnitude is quantitatively analysed. The result can be used to predict and evaluate the Pelton turbine performance

Numerical analysis of the bucket surface roughness effects in Pelton turbine

Science.gov (United States)

Xiao, Y. X.; Zeng, C. J.; Zhang, J.; Yan, Z. G.; Wang, Z. W.

2013-12-01

The internal flow of a Pelton turbine is quite complex. It is difficult to analyse the unsteady free water sheet flow in the rotating bucket owing to the lack of a sound theory. Affected by manufacturing technique and silt abrasion during the operation, the bucket surface roughness of Pelton turbine may be too great, and thereby influence unit performance. To investigate the effect of bucket roughness on Pelton turbine performance, this paper presents the numerical simulation of the interaction between the jet and the bucket in a Pelton turbine. The unsteady three-dimensional numerical simulations were performed with CFX code by using the SST turbulence model coupling the two-phase flow volume of fluid method. Different magnitude orders of bucket surface roughness were analysed and compared. Unsteady numerical results of the free water sheet flow patterns on bucket surface, torque and unit performance for each bucket surface roughness were generated. The total pressure distribution on bucket surface is used to show the free water sheet flow pattern on bucket surface. By comparing the variation of water sheet flow patterns on bucket surface with different roughness, this paper qualitatively analyses how the bucket surface roughness magnitude influences the impeding effect on free water sheet flow. Comparison of the torque variation of different bucket surface roughness highlighted the effect of the bucket surface roughness on the Pelton turbine output capacity. To further investigate the effect of bucket surface roughness on Pelton turbine performance, the relation between the relative efficiency loss rate and bucket surface roughness magnitude is quantitatively analysed. The result can be used to predict and evaluate the Pelton turbine performance.

UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

Directory of Open Access Journals (Sweden)

Saita M

2016-01-01

Full Text Available Makiko Saita,1 Takayuki Ikeda,1,2 Masahiro Yamada,1,3 Katsuhiko Kimoto,4 Masaichi Chang-Il Lee,5 Takahiro Ogawa1 1Division of Advanced Prosthodontics, Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Yokosuka, Japan; 3Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; 4Department of Prosthodontics and Oral Rehabilitation, 5Yokosuka-Shonan Disaster Health Emergency Research Center and ESR Laboratories, Kanagawa Dental University Graduate School of Dentistry, Yokosuka, Japan Background: Although biomimetic apatite coating is a promising way to provide titanium with osteoconductivity, the efficiency and quality of deposition is often poor. Most titanium implants have microscale surface morphology, and an addition of nanoscale features while preserving the micromorphology may provide further biological benefit. Here, we examined the effect of ultraviolet (UV light treatment of titanium, or photofunctionalization, on the efficacy of biomimetic apatite deposition on titanium and its biological capability.Methods and results: Micro-roughed titanium disks were prepared by acid-etching with sulfuric acid. Micro-roughened disks with or without photofunctionalization (20-minute exposure to UV light were immersed in simulated body fluid (SBF for 1 or 5 days. Photofunctionalized titanium disks were superhydrophilic and did not form surface air bubbles when immersed in SBF, whereas non-photofunctionalized disks were hydrophobic and largely covered with air bubbles during immersion. An apatite-related signal was observed by X-ray diffraction on photofunctionalized titanium after 1 day of SBF immersion, which was equivalent to the one observed after 5 days of immersion of control titanium. Scanning electron microscopy revealed nodular apatite deposition

THE EFFECT OF OPACIFIERS ON SURFACE ROUGHNESS OFCERAMIC GLAZES

Directory of Open Access Journals (Sweden)

R. Sarjahani

2016-03-01

Full Text Available Surface smoothness of ceramic glazes is always an important characteristic of ceramic glazes as a point of surface engineering studies. Surface roughness affects chemical resistivity, glossiness and stainabiliy of glazes. In fact, less surface roughness improves cleanability of the surface by the least usage amount of detergents. In this investigation, surface topography of two common opaque glazes, zirconia and titania-based, has been investigated. Crystallinity of the surface has been studied from SEM images, and comparison of EDS elemental results with phase analysis results of XRD. Surface roughness profile measured by Marsurf M300, shows that titania-based glaze is almost 24% percentage more smooth than zirconia based glaze. Surface smoothness is in relation with crystallinity of glaze surface, crystal type and crystal distribution in amorphous matrix phase

Comparison of optical methods for surface roughness characterization

DEFF Research Database (Denmark)

Feidenhans'l, Nikolaj Agentoft; Hansen, Poul Erik; Pilny, Lukas

2015-01-01

We report a study of the correlation between three optical methods for characterizing surface roughness: a laboratory scatterometer measuring the bi-directional reflection distribution function (BRDF instrument), a simple commercial scatterometer (rBRDF instrument), and a confocal optical profiler....... For each instrument, the effective range of spatial surface wavelengths is determined, and the common bandwidth used when comparing the evaluated roughness parameters. The compared roughness parameters are: the root-mean-square (RMS) profile deviation (Rq), the RMS profile slope (Rdq), and the variance...... of the scattering angle distribution (Aq). The twenty-two investigated samples were manufactured with several methods in order to obtain a suitable diversity of roughness patterns.Our study shows a one-to-one correlation of both the Rq and the Rdq roughness values when obtained with the BRDF and the confocal...

Single-layer model for surface roughness.

Science.gov (United States)

Carniglia, C K; Jensen, D G

2002-06-01

Random roughness of an optical surface reduces its specular reflectance and transmittance by the scattering of light. The reduction in reflectance can be modeled by a homogeneous layer on the surface if the refractive index of the layer is intermediate to the indices of the media on either side of the surface. Such a layer predicts an increase in the transmittance of the surface and therefore does not provide a valid model for the effects of scatter on the transmittance. Adding a small amount of absorption to the layer provides a model that predicts a reduction in both reflectance and transmittance. The absorbing layer model agrees with the predictions of a scalar scattering theory for a layer with a thickness that is twice the rms roughness of the surface. The extinction coefficient k for the layer is proportional to the thickness of the layer.

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

Science.gov (United States)

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.

Surface modification of porous titanium with rice husk as space holder

Science.gov (United States)

Wang, Xinsheng; Hou, Junjian; Liu, Yanpei

2018-06-01

Porous titanium was characterized after its surface modification by acid and alkali solution immersion. The results show that the acid surface treatment caused the emergence of flocculent sodium titanate and induced apatite formation. The surface modification of porous titanium promotes biological activation, and the application of porous titanium is also improved as an implant material because of the existence of C and Si.

A comparison RSM and ANN surface roughness models in thin-wall machining of Ti6Al4V using vegetable oils under MQL-condition

Science.gov (United States)

Mohruni, Amrifan Saladin; Yanis, Muhammad; Sharif, Safian; Yani, Irsyadi; Yuliwati, Erna; Ismail, Ahmad Fauzi; Shayfull, Zamree

2017-09-01

Thin-wall components as usually applied in the structural parts of aeronautical industry require significant challenges in machining. Unacceptable surface roughness can occur during machining of thin-wall. Titanium product such Ti6Al4V is mostly applied to get the appropriate surface texture in thin wall designed requirements. In this study, the comparison of the accuracy between Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) in the prediction of surface roughness was conducted. Furthermore, the machining tests were carried out under Minimum Quantity Lubrication (MQL) using AlCrN-coated carbide tools. The use of Coconut oil as cutting fluids was also chosen in order to evaluate its performance when involved in end milling. This selection of cutting fluids is based on the better performance of oxidative stability than that of other vegetable based cutting fluids. The cutting speed, feed rate, radial and axial depth of cut were used as independent variables, while surface roughness is evaluated as the dependent variable or output. The results showed that the feed rate is the most significant factors in increasing the surface roughness value followed by the radial depth of cut and lastly the axial depth of cut. In contrary, the surface becomes smoother with increasing the cutting speed. From a comparison of both methods, the ANN model delivered a better accuracy than the RSM model.

The contact sport of rough surfaces

Science.gov (United States)

Carpick, Robert W.

2018-01-01

Describing the way two surfaces touch and make contact may seem simple, but it is not. Fully describing the elastic deformation of ideally smooth contacting bodies, under even low applied pressure, involves second-order partial differential equations and fourth-rank elastic constant tensors. For more realistic rough surfaces, the problem becomes a multiscale exercise in surface-height statistics, even before including complex phenomena such as adhesion, plasticity, and fracture. A recent research competition, the “Contact Mechanics Challenge” (1), was designed to test various approximate methods for solving this problem. A hypothetical rough surface was generated, and the community was invited to model contact with this surface with competing theories for the calculation of properties, including contact area and pressure. A supercomputer-generated numerical solution was kept secret until competition entries were received. The comparison of results (2) provides insights into the relative merits of competing models and even experimental approaches to the problem.

The Influence of Surface Roughness on the Displacement of Osteogenic Bone Particles during Placement of Titanium Screw-Type Implants

NARCIS (Netherlands)

Tabassum, A.; Walboomers, F.; Wolke, J.G.C.; Meijer, G.J.; Jansen, J.A.

2011-01-01

Background: Previously, we demonstrated that bone debris, which is translocated during dental implant placement, has osteogenic potential. Therefore, it was hypothesized that implant surface roughness can influence the amount of translocated bone debris/particles and thereby the osteogenic response.

Influence of surface roughness on streptococcal adhesion forces to composite resins

NARCIS (Netherlands)

Mei, Li; Busscher, Henk J; van der Mei, Henny C; Ren, Yijin

OBJECTIVE: To determine streptococcal adhesion forces with composite resins with different surface roughness. METHODS: Polishing and grinding were applied to obtain smooth (roughness 20 nm), moderately rough (150 nm) and rough (350 nm) surfaces of two orthodontic, light-cured composites. Adhesion

Fuzzy Linguistic Optimization on Surface Roughness for CNC Turning

Directory of Open Access Journals (Sweden)

Tian-Syung Lan

2010-01-01

Full Text Available Surface roughness is often considered the main purpose in contemporary computer numerical controlled (CNC machining industry. Most existing optimization researches for CNC finish turning were either accomplished within certain manufacturing circumstances or achieved through numerous equipment operations. Therefore, a general deduction optimization scheme is deemed to be necessary for the industry. In this paper, the cutting depth, feed rate, speed, and tool nose runoff with low, medium, and high level are considered to optimize the surface roughness for finish turning based on L9(34 orthogonal array. Additionally, nine fuzzy control rules using triangle membership function with respective to five linguistic grades for surface roughness are constructed. Considering four input and twenty output intervals, the defuzzification using center of gravity is then completed. Thus, the optimum general fuzzy linguistic parameters can then be received. The confirmation experiment result showed that the surface roughness from the fuzzy linguistic optimization parameters is significantly advanced compared to that from the benchmark. This paper certainly proposes a general optimization scheme using orthogonal array fuzzy linguistic approach to the surface roughness for CNC turning with profound insight.

Narrow titanium oxide nanowires induced by femtosecond laser pulses on a titanium surface

Energy Technology Data Exchange (ETDEWEB)

Li, Hui; Li, Xian-Feng [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Zhang, Cheng-Yun [School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006 (China); Tie, Shao-Long [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Lan, Sheng, E-mail: slan@scnu.edu.cn [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

2017-02-28

Highlights: • Titanium oxide nanowires with a feature width as narrow as ∼20 nm were induced on a titanium surface by using femtosecond laser pulses at 400 nm. • An evolution of the surface structure from a high spatial frequency laser-induced periodic structure parallel to the laser polarization to a low spatial frequency one perpendicular to the laser polarization was observed with increasing irradiation pulse number. • The formation of the titanium oxide nanowires was confirmed by the energy dispersive spectroscopy measurements and the evolution of the surface structure was successfully interpreted by using the efficacy factor theory. - Abstract: The evolution of the nanostructure induced on a titanium (Ti) surface with increasing irradiation pulse number by using a 400-nm femtosecond laser was examined by using scanning electron microscopy. High spatial frequency periodic structures of TiO{sub 2} parallel to the laser polarization were initially observed because of the laser-induced oxidation of the Ti surface and the larger efficacy factor of TiO{sub 2} in this direction. Periodically aligned TiO{sub 2} nanowires with featured width as small as 20 nm were obtained. With increasing pulse number, however, low spatial frequency periodic structures of Ti perpendicular to the laser polarization became dominant because Ti possesses a larger efficacy factor in this direction. The competition between the high- and low-spatial frequency periodic structures is in good agreement with the prediction of the efficacy factor theory and it should also be observed in the femtosecond laser ablation of other metals which are easily oxidized in air.

Modeling superhydrophobic surfaces comprised of random roughness

Science.gov (United States)

Samaha, M. A.; Tafreshi, H. Vahedi; Gad-El-Hak, M.

2011-11-01

We model the performance of superhydrophobic surfaces comprised of randomly distributed roughness that resembles natural surfaces, or those produced via random deposition of hydrophobic particles. Such a fabrication method is far less expensive than ordered-microstructured fabrication. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridge configurations for pipe flows. The present results are compared with other theoretical and experimental studies. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

Effects of capillary condensation in adhesion between rough surfaces.

Science.gov (United States)

Wang, Jizeng; Qian, Jin; Gao, Huajian

2009-10-06

Experiments on the effects of humidity in adhesion between rough surfaces have shown that the adhesion energy remains constant below a critical relative humidity (RHcr) and then abruptly jumps to a higher value at RHcr before approaching its upper limit at 100% relative humidity. A model based on a hierarchical rough surface topography is proposed, which quantitatively explains the experimental observations and predicts two threshold RH values, RHcr and RHdry, which define three adhesion regimes: (1) RHRHcr, water menisci freely form and spread along the interface between the rough surfaces.

Effect of autoclaving on the surfaces of TiN -coated and conventional nickel-titanium rotary instruments.

Science.gov (United States)

Spagnuolo, G; Ametrano, G; D'Antò, V; Rengo, C; Simeone, M; Riccitiello, F; Amato, M

2012-12-01

To evaluate the effects of repeated autoclave sterilization cycles on surface topography of conventional nickel-titanium ( NiTi ) and titanium nitride ( TiN )-coated rotary instruments. A total of 60 NiTi rotary instruments, 30 ProTaper (Dentsply Maillefer) and 30 TiN -coated AlphaKite (Komet/Gebr. Brasseler), were analysed. Instruments were evaluated in the as-received condition and after 1, 5 and 10 sterilization cycles. After sterilization, the samples were observed using scanning electron microscope (SEM), and surface chemical analysis was performed on each instrument with energy dispersive X-ray spectroscopy (EDS). Moreover, the samples were analysed by atomic force microscopy (AFM), and roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova followed by Tukey's test. Scanning electron microscope observations revealed the presence of pitting and deep milling marks in all instruments. EDS analysis confirmed that both types of instruments were composed mainly of nickel and titanium, whilst AlphaKite had additional nitride. After multiple autoclave sterilization cycles, SEM examinations revealed an increase in surface alterations, and EDS values indicated changes in chemical surface composition in all instruments. Ra and RMS values of ProTaper significantly increased after 5 (P = 0.006) and 10 cycles (P = 0.002) with respect to the as-received instruments, whilst AlphaKite showed significant differences compared with the controls after 10 cycles (P = 0.03). Multiple autoclave sterilization cycles modified the surface topography and chemical composition of conventional and TiN -coated NiTi rotary instruments. © 2012 International Endodontic Journal.

Surface Functionalization of Orthopedic Titanium Implants with Bone Sialoprotein.

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Andreas Baranowski

Full Text Available Orthopedic implant failure due to aseptic loosening and mechanical instability remains a major problem in total joint replacement. Improving osseointegration at the bone-implant interface may reduce micromotion and loosening. Bone sialoprotein (BSP has been shown to enhance bone formation when coated onto titanium femoral implants and in rat calvarial defect models. However, the most appropriate method of BSP coating, the necessary level of BSP coating, and the effect of BSP coating on cell behavior remain largely unknown. In this study, BSP was covalently coupled to titanium surfaces via an aminosilane linker (APTES, and its properties were compared to BSP applied to titanium via physisorption and untreated titanium. Cell functions were examined using primary human osteoblasts (hOBs and L929 mouse fibroblasts. Gene expression of specific bone turnover markers at the RNA level was detected at different intervals. Cell adhesion to titanium surfaces treated with BSP via physisorption was not significantly different from that of untreated titanium at any time point, whereas BSP application via covalent coupling caused reduced cell adhesion during the first few hours in culture. Cell migration was increased on titanium disks that were treated with higher concentrations of BSP solution, independent of the coating method. During the early phases of hOB proliferation, a suppressive effect of BSP was observed independent of its concentration, particularly when BSP was applied to the titanium surface via physisorption. Although alkaline phosphatase activity was reduced in the BSP-coated titanium groups after 4 days in culture, increased calcium deposition was observed after 21 days. In particular, the gene expression level of RUNX2 was upregulated by BSP. The increase in calcium deposition and the stimulation of cell differentiation induced by BSP highlight its potential as a surface modifier that could enhance the osseointegration of orthopedic implants

Effect of surface roughness on the aerodynamic characteristics of a symmetrical airfoil

Energy Technology Data Exchange (ETDEWEB)

Chakroun, W.; Al-Mesri, I.; Al-Fahad, S.

2005-07-01

The objective of this study is to investigate the effect of surface roughness by varying the roughness size and location on the aerodynamic characteristics of the airfoil. Test were conducted on the symmetrical airfoil models NACA 0012 in which the nature of the surface was varied from smooth to very rough and at a chord Reynolds number of 1.5*10{sup 5}. Different airfoil models with various roughness sizes and roughness locations were tested for different angles of attack. Lift, drag and pressure coefficients were measured and velocity profiles were determined for the smooth and grit 36 roughened models. It is shown that as the surface roughness increases, the minimum drag also increases due to the increase of the skin friction and the lift decreases. Surface roughness is seen to delay the stall angle and also increase the lift in the stall region. The airfoil model with the roughness located at the trailing edge shows minimum drag and maximum lift up to the stall angle compared to the other cases of different roughness locations. It is confirmed that, for the rough surface, a turbulent boundary layer exists where the laminar boundary layer is encountered for the smooth surface at the same Reynolds number. The measured skin friction for the rough surface is larger than that for the smooth surface. (author)

Influence on proliferation and adhesion of human gingival fibroblasts from different titanium surface decontamination treatments: An in vitro study.

Science.gov (United States)

Cao, Jie; Wang, Tong; Pu, Yinfei; Tang, Zhihui; Meng, Huanxin

2018-03-01

To investigate the effects of different decontamination treatments on microstructure of titanium (Ti) surface as well as proliferation and adhesion of human gingival fibroblasts (HGFs). Ti discs with machined (M) and sand blasted, acid etched (SAE) surfaces were treated with five different decontamination treatments: (1) stainless steel curette (SSC), ultrasonic system with (2) straight carbon fiber tip (UCF) or (3) metal tip (UM), (4) rotating Ti brush (RTB), and (5) Er:YAG laser (30 mJ/pulse at 30 Hz). Surface roughness was analyzed under optical interferometry. HGFs were cultured on each disc. Proliferation and adhesive strength were analyzed. qRT-PCR and ELISA were performed to detect the RNA and protein expression of FAK, ITGB1, COL1A1, and FN1 respectively from different Ti surfaces. Surface roughness increased on M surface. Proliferation, adhesive strength and gene expression were higher on M surface than SAE surface. Decontamination treatments affected surface parameters significantly (P < 0.001), making M surface less smooth while SAE surface became less rough. SSC, UCF, UM and RTB decreased proliferation on M surfaces significantly (P < 0.05). UCF, RTB and laser increased proliferation on SAE surface significantly (P < 0.05). UM decreased adhesive strength on M surface significantly and laser increased adhesive strength on SAE surface significantly (P < 0.05). Gene expression increased with time and was altered by decontamination treatments significantly (P < 0.001). Decontamination treatments influence surface roughness and cell behavior of HGFs. Laser might be an optimal decontamination treatment which has the least negative effect on M surface and the most positive effect on SAE surface. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cassie state robustness of plasma generated randomly nano-rough surfaces

Energy Technology Data Exchange (ETDEWEB)

Di Mundo, Rosa, E-mail: rosa.dimundo@poliba.it; Bottiglione, Francesco; Carbone, Giuseppe

2014-10-15

Graphical abstract: - Highlights: • Superhydrophobic randomly rough surfaces are generated by plasma etching. • Statistical analysis of roughness allows calculation of theWenzel roughness factor, r{sub W.} • A r{sub W} threshold is theoretically determined, above which superhydrophobicity is “robust”. • Dynamic wetting, e.g. with high speed impacting drops, confirms this prediction. - Abstract: Superhydrophobic surfaces are effective in practical applications provided they are “robust superhydrophobic”, i.e. able to retain the Cassie state, i.e. with water suspended onto the surface protrusions, even under severe conditions (high pressure, vibrations, high speed impact, etc.). We show that for randomly rough surfaces, given the Young angle, Cassie states are robust when a threshold value of the Wenzel roughness factor, r{sub W}, is exceeded. In particular, superhydrophobic nano-textured surfaces have been generated by self-masked plasma etching. In view of their random roughness, topography features, acquired by Atomic Force Microscopy, have been statistically analyzed in order to gain information on statistical parameters such as power spectral density, fractal dimension and Wenzel roughness factor (r{sub W}), which has been used to assess Cassie state robustness. Results indicate that randomly rough surfaces produced by plasma at high power or long treatment duration, which are also fractal self-affine, have a r{sub W} higher than the theoretical threshold, thus for them a robust superhydrophobicity is predicted. In agreement with this, under dynamic wetting conditionson these surfaces the most pronounced superhydrophobic character has been appreciated: they show the lowest contact angle hysteresis and result in the sharpest bouncing when hit by drops at high impact velocity.

Osteoblasts generate an osteogenic microenvironment when grown on surfaces with rough microtopographies

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Boyan B. D.

2003-10-01

Full Text Available Osteoblasts respond to microarchitectural features of their substrate. On smooth surfaces (tissue culture plastic, tissue culture glass, and titanium, the cells attach and proliferate but they exhibit relatively low expression of differentiation markers in monolayer cultures, even when confluent. When grown on microrough Ti surfaces with an average roughness (Ra of 4-7 µm, proliferation is reduced but differentiation is enhanced and in some cases, is synergistic with the effects of surface microtopography. In addition, cells on microrough Ti substrates form hydroxyapatite in a manner that is more typical of bone than do cells cultured on smooth surfaces. Osteoblasts also respond to growth factors and cytokines in a surface-dependent manner. On rougher surfaces, the effects of regulatory factors like 1alpha,25(OH2D3 or 17beta-estradiol are enhanced. The response to the surface is mediated by integrins, which signal to the cell through many of the same mechanisms used by growth factors and hormones. Studies using PEG-modified surfaces indicate that increased differentiation may be related to altered attachment to the surface. When osteoblasts are grown on surfaces with chemistries or microarchitectures that reduce cell attachment and proliferation, and enhance differentiation, the cells tend to increase production of factors like TGF-beta1 that promote osteogenesis while decreasing osteoclastic activity. Thus, on microrough Ti surface, osteoblasts create a microenvironment conducive to new bone formation.

Comparison of optical methods for surface roughness characterization

International Nuclear Information System (INIS)

Feidenhans’l, Nikolaj A; Hansen, Poul-Erik; Madsen, Morten H; Petersen, Jan C; Pilný, Lukáš; Bissacco, Giuliano; Taboryski, Rafael

2015-01-01

We report a study of the correlation between three optical methods for characterizing surface roughness: a laboratory scatterometer measuring the bi-directional reflection distribution function (BRDF instrument), a simple commercial scatterometer (rBRDF instrument), and a confocal optical profiler. For each instrument, the effective range of spatial surface wavelengths is determined, and the common bandwidth used when comparing the evaluated roughness parameters. The compared roughness parameters are: the root-mean-square (RMS) profile deviation (Rq), the RMS profile slope (Rdq), and the variance of the scattering angle distribution (Aq). The twenty-two investigated samples were manufactured with several methods in order to obtain a suitable diversity of roughness patterns.Our study shows a one-to-one correlation of both the Rq and the Rdq roughness values when obtained with the BRDF and the confocal instruments, if the common bandwidth is applied. Likewise, a correlation is observed when determining the Aq value with the BRDF and the rBRDF instruments.Furthermore, we show that it is possible to determine the Rq value from the Aq value, by applying a simple transfer function derived from the instrument comparisons. The presented method is validated for surfaces with predominantly 1D roughness, i.e. consisting of parallel grooves of various periods, and a reflectance similar to stainless steel. The Rq values are predicted with an accuracy of 38% at the 95% confidence interval. (paper)

Surface roughness control by extreme ultraviolet (EUV) radiation

Science.gov (United States)

Ahad, Inam Ul; Obeidi, Muhannad Ahmed; Budner, Bogusław; Bartnik, Andrzej; Fiedorowicz, Henryk; Brabazon, Dermot

2017-10-01

Surface roughness control of polymeric materials is often desirable in various biomedical engineering applications related to biocompatibility control, separation science and surface wettability control. In this study, Polyethylene terephthalate (PET) polymer films were irradiated with Extreme ultraviolet (EUV) photons in nitrogen environment and investigations were performed on surface roughness modification via EUV exposure. The samples were irradiated at 3 mm and 4 mm distance from the focal spot to investigate the effect of EUV fluence on topography. The topography of the EUV treated PET samples were studied by AFM. The detailed scanning was also performed on the sample irradiated at 3 mm. It was observed that the average surface roughness of PET samples was increased from 9 nm (pristine sample) to 280 nm and 253 nm for EUV irradiated samples. Detailed AFM studies confirmed the presence of 1.8 mm wide period U-shaped channels in EUV exposed PET samples. The walls of the channels were having FWHM of about 0.4 mm. The channels were created due to translatory movements of the sample in horizontal and transverse directions during the EUV exposure. The increased surface roughness is useful for many applications. The nanoscale channels fabricated by EUV exposure could be interesting for microfluidic applications based on lab-on-a-chip (LOC) devices.

The surface roughness and planetary boundary layer

Science.gov (United States)

Telford, James W.

1980-03-01

Applications of the entrainment process to layers at the boundary, which meet the self similarity requirements of the logarithmic profile, have been studied. By accepting that turbulence has dominating scales related in scale length to the height above the surface, a layer structure is postulated wherein exchange is rapid enough to keep the layers internally uniform. The diffusion rate is then controlled by entrainment between layers. It has been shown that theoretical relationships derived on the basis of using a single layer of this type give quantitatively correct factors relating the turbulence, wind and shear stress for very rough surface conditions. For less rough surfaces, the surface boundary layer can be divided into several layers interacting by entrainment across each interface. This analysis leads to the following quantitatively correct formula compared to published measurements. 1 24_2004_Article_BF00877766_TeX2GIFE1.gif {σ _w }/{u^* } = ( {2/{9Aa}} )^{{1/4}} ( {1 - 3^{{1/2}{ a/k{d_n }/z{σ _w }/{u^* }z/L} )^{{1/4}} = 1.28(1 - 0.945({{σ _w }/{u^* }}}) {{z/L}})^{{1/4 where u^* = ( {{tau/ρ}}^{{1/2}}, σ w is the standard deviation of the vertical velocity, z is the height and L is the Obukhov scale lenght. The constants a, A, k and d n are the entrainment constant, the turbulence decay constant, Von Karman's constant, and the layer depth derived from the theory. Of these, a and A, are universal constants and not empirically determined for the boundary layer. Thus the turbulence needed for the plume model of convection, which resides above these layers and reaches to the inversion, is determined by the shear stress and the heat flux in the surface layers. This model applies to convection in cool air over a warm sea. The whole field is now determined except for the temperature of the air relative to the water, and the wind, which need a further parameter describing sea surface roughness. As a first stop to describing a surface where roughness elements

Friction and adhesion of gecko-inspired PDMS flaps on rough surfaces.

Science.gov (United States)

Yu, Jing; Chary, Sathya; Das, Saurabh; Tamelier, John; Turner, Kimberly L; Israelachvili, Jacob N

2012-08-07

Geckos have developed a unique hierarchical structure to maintain climbing ability on surfaces with different roughness, one of the extremely important parameters that affect the friction and adhesion forces between two surfaces. Although much attention has been paid on fabricating various structures that mimic the hierarchical structure of a gecko foot, yet no systematic effort, in experiment or theory, has been made to quantify the effect of surface roughness on the performance of the fabricated structures that mimic the hierarchical structure of geckos. Using a modified surface forces apparatus (SFA), we measured the adhesion and friction forces between microfabricated tilted PDMS flaps and optically smooth SiO(2) and rough SiO(2) surfaces created by plasma etching. Anisotropic adhesion and friction forces were measured when sliding the top glass surface along (+y) and against (-y) the tilted direction of the flaps. Increasing the surface roughness first increased the adhesion and friction forces measured between the flaps and the rough surface due to topological matching of the two surfaces but then led to a rapid decrease in both of these forces. Our results demonstrate that the surface roughness significantly affects the performance of gecko mimetic adhesives and that different surface textures can either increase or decrease the adhesion and friction forces of the fabricated adhesives.

Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

Energy Technology Data Exchange (ETDEWEB)

Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Haung, Chiung-Fang [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Division of Family and Operative Dentistry, Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Shyu, Shih-Shiun [Department of Dentistry, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 231, Taiwan (China); Chou, Yen-Ru [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Graduate Institute of Biomedical Materials and Tissue Engineering, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Peng, Pei-Wen, E-mail: apon@tmu.edu.tw [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); and others

2015-08-15

In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

Enhanced Hydrophilicity and Protein Adsorption of Titanium Surface by Sodium Bicarbonate Solution

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Shengnan Jia

2015-01-01

Full Text Available The aim of this study was to investigate a novel and convenient method of chemical treatment to modify the hydrophilicity of titanium surfaces. Sand-blasted and acid-etched (SLA titanium surfaces and machined titanium surfaces were treated with sodium bicarbonate (NaHCO3 solution. The wetting behavior of both kinds of surfaces was measured by water contact angle (WCA test. The surface microstructure was assessed with scanning electron microscopy (SEM and three-dimensional (3D optical microscopy. The elemental compositions of the surfaces were analyzed by X-ray photoelectron spectroscopy (XPS. The protein adsorption analysis was performed with fibronectin. Results showed that, after 1 M NaHCO3 treatment, the hydrophilicity of both SLA and machined surfaces was enhanced. No significant microstructural change presented on titanium surfaces after NaHCO3 treatment. The deprotonation and ion exchange activities might cause the enhanced hydrophilicity of titanium surfaces. The increased protein adsorption of NaHCO3-treated SLA surfaces might indicate their improved tissue-integration in clinical use.

Deposition of silver nanoparticles on titanium surface for antibacterial effect

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Liao Juan

2010-04-01

Full Text Available Liao Juan1, Zhu Zhimin3, Mo Anchun1,2, Li Lei1, Zhang Jingchao11State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; 2Department of Dental Implant, West China Stomatology Hospital, Sichuan University, Chengdu 610041, PR China; 3Department of Prosthodontics, West China Stomatology Hospital, Sichuan University, Chengdu 610041, PR ChinaAbstract: Microbial colonization on implanted devices and biofilm formation is a recurrent complication in implant surgery and may result in loss of implants. The aim of this study was to deposit silver nanoparticles on a titanium surface to obtain antibacterial properties. In the present study, we prepared a silver nanoparticle-modified titanium (Ti-nAg surface using silanization method. The morphology and chemical components of the Ti-nAg surface were characterized by scanning electron microscopy (SEM equipped with energy-dispersive spectroscopy (EDS. Two species of bacteria, Staphylococcus aureus and Escherichia coli, were utilized to test the antibacterial effect of the Ti-nAg treated surface. The SEM examination revealed that a small quantity of silver nanoparticles was sparsely deposited on the titanium surface. The diameter of these nanoparticles ranged from ten to several hundred nm. EDS analyses revealed that there was 4.26% of Ag present on the surface. After a 24-hour incubation, 94% of Staphylococcus aureus and over 95% of Escherichia coli had been killed on the Ti-nAg surface, and the SEM examination of anti-adhesive efficacy test showed that there were less bacteria attached to Ti-nAg surface than to a control surface of untreated Titanium. These data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.Keywords: nano-silver, titanium, antibacterial activity, silanization method

Response Ant Colony Optimization of End Milling Surface Roughness

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Ahmed N. Abd Alla

2010-03-01

Full Text Available Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6 with Response Ant Colony Optimization (RACO. The approach is based on Response Surface Method (RSM and Ant Colony Optimization (ACO. The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth. The first order model indicates that the feedrate is the most significant factor affecting surface roughness.

Experimental Study on the Axis Line Deflection of Ti6A14V Titanium Alloy in Gun-Drilling Process

Science.gov (United States)

Li, Liang; Xue, Hu; Wu, Peng

2018-01-01

Titanium alloy is widely used in aerospace industry, but it is also a typical difficult-to-cut material. During Deep hole drilling of the shaft parts of a certain large aircraft, there are problems of bad surface roughness, chip control and axis deviation, so experiments on gun-drilling of Ti6A14V titanium alloy were carried out to measure the axis line deflection, diameter error and surface integrity, and the reasons of these errors were analyzed. Then, the optimized process parameter was obtained during gun-drilling of Ti6A14V titanium alloy with deep hole diameter of 17mm. Finally, we finished the deep hole drilling of 860mm while the comprehensive error is smaller than 0.2mm and the surface roughness is less than 1.6μm.

Simple model of surface roughness for binary collision sputtering simulations

Energy Technology Data Exchange (ETDEWEB)

Lindsey, Sloan J. [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Hobler, Gerhard, E-mail: gerhard.hobler@tuwien.ac.at [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Maciążek, Dawid; Postawa, Zbigniew [Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30348 Kraków (Poland)

2017-02-15

Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.

Simple model of surface roughness for binary collision sputtering simulations

International Nuclear Information System (INIS)

Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

2017-01-01

Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.

Effects of surface roughness on plastic strain localization in polycrystalline aggregates

Directory of Open Access Journals (Sweden)

Guilhem Yoann

2014-06-01

Full Text Available The surface state of mechanical components differs according to applied loadings. Industrial processes may produce specific features at the surface, such as roughness, local hardening, residual stresses or recrystallization. Under fatigue loading, all these parameters will affect the component lifetime, but in different manner. A better understanding of each surface state parameter, separately first and then all combined, will provide a better prediction of fatigue life. The study focuses on the effect of surface roughness. Crystal plasticity finite element computations have been carried out on three-dimensional polycrystalline aggregates with different roughness levels. Local mechanical fields have been analyzed both at the surface and inside the bulk to highlight the competition between crystallography and roughness to impose localization patterns. As soon as surface roughness is strong enough, classical localization bands driven by grains orientation are replaced by localizations patterns driven by the local roughness topology. Nevertheless, this effect tends to decrease gradually under the surface, and it becomes usually negligible after the first layer of grains. The discussion allows us to characterize the influence of the surface state on the local mechanical fields.

Titanium nanostructures for biomedical applications

Science.gov (United States)

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

2015-02-01

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

Titanium nanostructures for biomedical applications

International Nuclear Information System (INIS)

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

2015-01-01

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

Elastic–plastic adhesive contact of non-Gaussian rough surfaces

Indian Academy of Sciences (India)

Grinding, milling, honing and abrasion processes produce grooved surfaces with negative ... This may be defined as λ = π2RH4σ/(18K2γ2) where H is the hardness ... The effect of surface roughness on adhesion at the contact of rough solids ...

Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires

OpenAIRE

Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria Jr, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

2017-01-01

Abstract The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Ni...

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

Science.gov (United States)

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

Assessment of Surface Area Characteristics of Dental Implants with Gradual Bioactive Surface Treatment

Science.gov (United States)

Czan, Andrej; Babík, Ondrej; Miklos, Matej; Záušková, Lucia; Mezencevová, Viktória

2017-10-01

Since most of the implant surface is in direct contact with bone tissue, shape and integrity of said surface has great influence on successful osseointegration. Among other characteristics that predetermine titanium of different grades of pureness as ideal biomaterial, titanium shows high mechanical strength making precise miniature machining increasingly difficult. Current titanium-based implants are often anodized due to colour coding. This anodized layer has important functional properties for right usage and also bio-compatibility of dental implants. Physical method of anodizing and usage of anodizing mediums has a significant influence on the surface quality and itself functionality. However, basic requirement of the dental implant with satisfactory properties is quality of machined surface before anodizing. Roughness, for example, is factor affecting of time length of anodizing operation and so whole productivity. The paper is focused on monitoring of surface and area characteristics, such as roughness or surface integrity after different cutting conditions of miniature machining of dental implants and their impact on suitability for creation of satisfactory anodized layer with the correct biocompatible functional properties.

[The change of bacterial adhesion during deposition nitrogen-diamond like carbon coating on pure titanium].

Science.gov (United States)

Yin, Lu; Xiao, Yun

2011-10-01

The aim of this study was to observe the change of bacterial adhesion on pure titanium coated with nitrogen-diamond like carbon (N-DLC) films and to guide the clinical application. N-DLC was deposited on titanium using ion plating machine, TiN film, anodic oxide film and non-deposition were used as control, then made specimens adhering on the surface of resin denture base for 6 months. The adhesion of Saccharomyces albicans on the titanium surface was observed using scanning electron microscope, and the roughness was tested by roughness detector. The number of Saccharomyces albicans adhering on diamond-like carbon film was significantly less than on the other groups (P DLC film was less than other group (P coated with N-DLC film reduced the adhesion of Saccharomyces albicans after clinical application, thereby reduced the risk of denture stomatitis.

Investigation of surface roughness influence on hyperbolic metamaterial performance

Directory of Open Access Journals (Sweden)

S. Kozik

2014-12-01

Full Text Available The main goal of this work was to introduce simple model of surface roughness which does not involve objects with complicated shapes and could help to reduce computational costs. We described and proved numerically that the influence of surface roughness at the interfaces in metal-dielectric composite materials could be described by proper selection of refractive index of dielectric layers. Our calculations show that this model works for roughness with RMS value about 1 nm and below.

Simple model of surface roughness for binary collision sputtering simulations

Science.gov (United States)

Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

2017-02-01

It has been shown that surface roughness can strongly influence the sputtering yield - especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the "density gradient model") which imitates surface roughness effects. In the model, the target's atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient - leading to increased sputtering yields, similar in effect to surface roughness.

LASER SURFACE MODIFICATION OF TITANIUM ALLOYS — A REVIEW

OpenAIRE

Y. S. TIAN; C. Z. CHEN; D. Y. WANG; T. Q. LEI

2005-01-01

Recent developments of laser surface modification of titanium alloys for increasing their corrosion, wear and oxidation resistance are introduced. The effects of laser processing parameters on the resulting surface properties of titanium alloys are reviewed. The problems to be solved and the prospects in the field of laser modification of Ti alloys are discussed. Due to the intrinsic properties, a laser beam can be focused onto the metallic surface to produce a broad range of treatments depen...

Calibration of surface roughness standards

DEFF Research Database (Denmark)

Thalmann, R.; Nicolet, A.; Meli, F.

2016-01-01

organisations. Five surface texture standards of different type were circulated and on each of the standards several roughness parameters according to the standard ISO 4287 had to be determined. 32 out of 395 individual results were not consistent with the reference value. After some corrective actions...

Soil surface roughness decay in contrasting climates, tillage types and management systems

Science.gov (United States)

Vidal Vázquez, Eva; Bertol, Ildegardis; Tondello Barbosa, Fabricio; Paz-Ferreiro, Jorge

2014-05-01

Soil surface roughness describes the variations in the elevation of the soil surface. Such variations define the soil surface microrelief, which is characterized by a high spatial variability. Soil surface roughness is a property affecting many processes such as depression storage, infiltration, sediment generation, storage and transport and runoff routing. Therefore the soil surface microrelief is a key element in hydrology and soil erosion processes at different spatial scales as for example at the plot, field or catchment scale. In agricultural land soil surface roughness is mainly created by tillage operations, which promote to different extent the formation of microdepressions and microelevations and increase infiltration and temporal retention of water. The decay of soil surface roughness has been demonstrated to be mainly driven by rain height and rain intensity, and to depend also on runoff, aggregate stability, soil reface porosity and soil surface density. Soil roughness formation and decay may be also influenced by antecedent soil moisture (either before tillage or rain), quantity and type of plant residues over the soil surface and soil composition. Characterization of the rate and intensity of soil surface roughness decay provides valuable information about the degradation of the upper most soil surface layer before soil erosion has been initiated or at the very beginning of soil runoff and erosion processes. We analyzed the rate of decay of soil surface roughness from several experiments conducted in two regions under temperate and subtropical climate and with contrasting land use systems. The data sets studied were obtained both under natural and simulated rainfall for various soil tillage and management types. Soil surface roughness decay was characterized bay several parameters, including classic and single parameters such as the random roughness or the tortuosity and parameters based on advanced geostatistical methods or on the fractal theory. Our

Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires.

Science.gov (United States)

Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

2017-01-01

The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Niti (Nitinol-NS). The initial roughness was evaluated with a rugosimeter. After that, the wires were submitted to flexural test in an universal testing machine. Each wire was deflected up to 2 mm at a speed of 1 mm/min. After flexural test, the roughness of the wires was evaluted on the same surface as that used for the initial evaluation. The data of roughness and flexural strength were analyzed by one-way ANOVA and Tukey's test (a=0.05). Student t-test compared roughness before and after deflection (a =0.05). The roughness of S and ANT (epoxy resin and PTFE-coated wires, respectively), before and after deflection, was significantly higher than the other groups (p<0.05). Wire deflection significantly increased the roughness of the wires S and STC (p<0.05). The flexural strength of groups FSE and NS (PTFE and uncoated) was higher compared with that of the other groups (p<0.05). We concluded that the roughness and flexural strength of the orthodontic wires does not depend on the type of the esthetic coating, but it is influenced by the method of application of this coating. The deflection can increase the roughness of the esthetic orthodontic wires.

The precipitation behavior of titanium carbide on the surface of SUS 321 stainless steel

International Nuclear Information System (INIS)

Yoshihara, Kazuhiro; Nii, Kazuyoshi

1982-01-01

The surface composition of SUS 321 stainless steel at high temperatures was observed in vacuum with Auger electron spectroscopy. The precipitation of titanium carbide was found on the surface of SUS 321. The thickness of precipitated titanium carbide layer increased in proportion to the square root of annealing time and became about 0.05 μm after heated at 1100 K for 432 ks. The precipitated titanium carbide was not replaced by the most surface active element sulfur, and remained stable on the surface. The precipitated layer, however, was not even and had many holes about 1 μm in diameter. The bottom of a hole was SUS 321, on which phosphorus, oxygen and sulfur segregated. As the annealing time was prolonged, these segregants were replaced one by one in the order of the surface activity, and finally the most surface active element, sulfur, remained on the bottom of the hole. Moreover, sulfur diffused over the outside of the hole. The precipitation of titanium carbide on the surface occurred according to the following processes: (1) The titanium and carbon which had been dissolved in the bulk diffused onto the surface of the stainless steel. (2) The titanium carbide which had been precipitated in the bulk dissolved because the concentration of titanum and carbon fell under their solubility limits in the bulk. (3) The titanium and carbon diffused onto the surface which was exposed to vacuum. (4) The titanium and carbon recombined into titanium carbide and precipitated on the surface. The growth rate of the thickness of the precipitated layer was controlled by the diffusion of titanium and carbon in the precipitated titanium carbide. (J.P.N.)

Effect of alkali treatment on surface morphology of titanium

Energy Technology Data Exchange (ETDEWEB)

Tan, K. J., E-mail: gd130056@siswa.uthm.edu.my; Wahab, M. A. A., E-mail: cd110006@siswa.uthm.edu.my; Mahmod, S., E-mail: cd110201@siswa.uthm.edu.my; Idris, M. I., E-mail: izwana@uthm.edu.my; Abdullah, H. Z., E-mail: hasan@uthm.edu.my [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor (Malaysia)

2015-07-22

Alkali and heat treatments were first introduced by Kim et al. to prepare a bioactive surface on titanium. This method has been proven very effective and widely used in other studies to promote titanium osteointegration. This study aims to investigate further the effect of alkali treatment on surface morphology of high purity titanium. High purity titanium foils were immersed in NaOH aqueous solutions of 0.5 M, 5 M and 15 M at 60°C and 80 °C for 1, 3 and 7 days. The surface morphology was examined using Field Emission Scanning Electron Microscope (FESEM). The obtained phases were analysed using Fourier Transform Infrared Spectroscopy (FTIR) in the spectra range of 4000-600 cm{sup −1} at 4 cm{sup −1} resolution and 50 scans. At the same soaking temperature and soaking time, a thicker porous network was observed with increasing concentration of NaOH. At the same soaking temperature, a much porous structure was observed with increasing soaking time. At constant alkali concentration, more homogenously distributed porous surface structure was observed with increasing soaking temperature.

Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

Science.gov (United States)

Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

2018-03-01

Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

Laser bioengineering of glass-titanium implants surface

Science.gov (United States)

Lusquiños, F.; Arias-González, F.; Penide, J.; del Val, J.; Comesaña, R.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pascual, M. J.; Durán, A.; Pou, J.

2013-11-01

Osseointegration is the mean challenge when surgical treatments fight against load-bearing bone diseases. Absolute bone replacement by a synthetic implant has to be completed not only from the mechanics point of view, but also from a biological approach. Suitable strength, resilience and stress distribution of titanium alloy implants are spoiled by the lack of optimal biological characteristics. The inert quality of extra low interstitial titanium alloy, which make it the most attractive metallic alloy for biomedical applications, oppose to an ideal surface with bone cell affinity, and capable to stimulate bone attachment bone growth. Diverse laser treatments have been proven as effective tools to modify surface properties, such as wettability in contact to physiological fluids, or osteoblast guided and slightly enhanced attachment. The laser surface cladding can go beyond by providing titanium alloy surfaces with osteoconduction and osteoinduction properties. In this research work, the laser radiation is used to produce bioactive glass coatings on Ti6Al4V alloy substrates. Specific silicate bioactive glass compositions has been investigated to achieve suitable surface tension and viscosity temperature behavior during processing, and to provide with the required release of bone growth gene up regulation agents in the course of resorption mediated by physiological fluids. The produced coatings and interfaces, the surface osteoconduction properties, and the chemical species release in simulated physiological fluid were characterized by scanning electron microscopy (SEM), hot stage microscopy (HSM), X-ray diffraction (XRD), X ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR).

Simplified Approach to Predicting Rough Surface Transition

Science.gov (United States)

Boyle, Robert J.; Stripf, Matthias

2009-01-01

Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consiste nt with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparison s are presented with published experimental data. Some of the data ar e for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach ta ken in this analysis is to treat the roughness in a statistical sense , consistent with what would be obtained from blades measured after e xposure to actual engine environments. An approach is given to determ ine the equivalent sand grain roughness from the statistics of the re gular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test co nditions. Additional comparisons are made with experimental heat tran sfer data, where the roughness geometries are both regular as well a s statistical. Using the developed analysis, heat transfer calculatio ns are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

Enhancing Surface Finish of Additively Manufactured Titanium and Cobalt Chrome Elements Using Laser Based Finishing

Science.gov (United States)

Gora, Wojciech S.; Tian, Yingtao; Cabo, Aldara Pan; Ardron, Marcus; Maier, Robert R. J.; Prangnell, Philip; Weston, Nicholas J.; Hand, Duncan P.

Additive manufacturing (AM) offers the possibility of creating a complex free form object as a single element, which is not possible using traditional mechanical machining. Unfortunately the typically rough surface finish of additively manufactured parts is unsuitable for many applications. As a result AM parts must be post-processed; typically mechanically machined and/or and polished using either chemical or mechanical techniques (both of which have their limitations). Laser based polishing is based on remelting of a very thin surface layer and it offers potential as a highly repeatable, higher speed process capable of selective area polishing, and without any waste problems (no abrasives or liquids). In this paper an in-depth investigation of CW laser polishing of titanium and cobalt chrome AM elements is presented. The impact of different scanning strategies, laser parameters and initial surface condition on the achieved surface finish is evaluated.

Modeling of surface roughness effects on Stokes flow in circular pipes

Science.gov (United States)

Song, Siyuan; Yang, Xiaohu; Xin, Fengxian; Lu, Tian Jian

2018-02-01

Fluid flow and pressure drop across a channel are significantly influenced by surface roughness on a channel wall. The present study investigates the effects of periodically structured surface roughness upon flow field and pressure drop in a circular pipe at low Reynolds numbers. The periodic roughness considered exhibits sinusoidal, triangular, and rectangular morphologies, with the relative roughness (i.e., ratio of the amplitude of surface roughness to hydraulic diameter of the pipe) no more than 0.2. Based upon a revised perturbation theory, a theoretical model is developed to quantify the effect of roughness on fully developed Stokes flow in the pipe. The ratio of static flow resistivity and the ratio of the Darcy friction factor between rough and smooth pipes are expressed in four-order approximate formulations, which are validated against numerical simulation results. The relative roughness and the wave number are identified as the two key parameters affecting the static flow resistivity and the Darcy friction factor.

Ultrasonic Surface Treatment of Titanium Alloys. The Submicrocrystalline State

Science.gov (United States)

Klimenov, V. A.; Vlasov, V. A.; Borozna, V. Y.; Klopotov, A. A.

2015-09-01

The paper presents the results of the research on improvement of physical-and- mechanical properties of titanium alloys VT1-0 and VT6 by modification of surfaces using ultrasonic treatment, and a comprehensive study of the microstructure and mechanical properties of modified surface layers. It has been established that exposure to ultrasonic treatment leads to formation in the surface layer of a structure with an average size of elements 50 - 100 nm, depending on the brand of titanium alloy.

Multifractal scaling analysis of autopoisoning reactions over a rough surface

International Nuclear Information System (INIS)

Chaudhari, Ajay; Yan, Ching-Cher Sanders; Lee, S.-L.

2003-01-01

Decay type diffusion-limited reactions (DLR) over a rough surface generated by a random deposition model were performed. To study the effect of the decay profile on the reaction probability distribution (RPD), multifractal scaling analysis has been carried out. The dynamics of these autopoisoning reactions are controlled by the two parameters in the decay function, namely, the initial sticking probability (P ini ) of every site and the decay rate (m). The smaller the decay rate, the narrower is the range of α values in the α-f(α) multifractal spectrum. The results are compared with the earlier work of DLR over a surface of diffusion-limited aggregation (DLA). We also considered here the autopoisoning reactions over a smooth surface for comparing our results, which show clearly how the roughness affects the chemical reactions. The q-τ(q) multifractal curves for the smooth surface are linear whereas those for the rough surface are nonlinear. The range of α values in the case of a rough surface is wider than that of the smooth surface

Surface characterization and corrosion behavior of micro-arc oxidized Ti surface modified with hydrothermal treatment and chitosan coating

International Nuclear Information System (INIS)

Neupane, Madhav Prasad; Park, Il Song; Lee, Min Ho

2014-01-01

In the present work, we describe the surface modification of commercially pure titanium (CP-Ti) by a composite/multilayer coating approach for biomedical applications. CP-Ti samples were treated by micro-arc oxidation (MAO) and subsequently some of the samples were coated with chitosan (Chi) by dip coating method, while others were subjected to hydrothermal treatment (HT) followed by chitosan coating. The MAO, MAO/Chi, and MAO/HT/Chi coated Ti were characterized and their characteristics were compared with CP-Ti. X-ray diffraction and scanning electron microscopy were used to assess the structural and morphological characteristics. The average surface roughness was determined using a surface profilometer. The corrosion resistance of untreated and surface modified Ti in commercial saline at 298 K was evaluated by potentiodynamic polarization test. The results indicated that the chitosan coating is very well integrated with the MAO and MAO/HT coating by physically interlocking itself with the coated layer and almost sealed all the pores. The surface roughness of hydrothermally treated and chitosan coated MAO film was superior evidently to that with other sample groups. The corrosion studies demonstrated that the MAO, hydrothermally treated and chitosan coated sample enhanced the corrosion resistance of titanium. The result indicates that fabrication of hydrothermally treated MAO surface coatings with chitosan is a significant approach to protect the titanium from corrosion, hence enhancing the potential use of titanium as bio-implants. - Highlights: • Micro-arc oxidized (MAO) and hydrothermally treated (HT) Ti surfaces are coated with chitosan (Chi). • The MAO/HT/Chi surface exhibits pores sealing and enhanced the surface roughness. • The MAO/HT/Chi surface significantly increase the corrosion resistance. • The MAO/HT/Chi can be a potential surface of titanium for bio-implants

Surface roughness of composite resins subjected to hydrochloric acid.

Science.gov (United States)

Roque, Ana Carolina Cabral; Bohner, Lauren Oliveira Lima; de Godoi, Ana Paula Terossi; Colucci, Vivian; Corona, Silmara Aparecida Milori; Catirse, Alma Blásida Concepción Elizaur Benitez

2015-01-01

The purpose of this study was to determine the influence of hydrochloric acid on surface roughness of composite resins subjected to brushing. Sixty samples measuring 2 mm thick x 6 mm diameter were prepared and used as experimental units. The study presented a 3x2 factorial design, in which the factors were composite resin (n=20), at 3 levels: microhybrid composite (Z100), nanofilled composite (FiltekTM Supreme), nanohybrid composite (Ice), and acid challenge (n=10) at 2 levels: absence and presence. Acid challenge was performed by immersion of specimens in hydrochloric acid (pH 1.2) for 1 min, 4 times per day for 7 days. The specimens not subjected to acid challenge were stored in 15 mL of artificial saliva at 37 oC. Afterwards, all specimens were submitted to abrasive challenge by a brushing cycle performed with a 200 g weight at a speed of 356 rpm, totaling 17.8 cycles. Surface roughness measurements (Ra) were performed and analyzed by ANOVA and Tukey test (p≤0.05). Surface roughness values were higher in the presence (1.07±0.24) as compared with the absence of hydrochloric acid (0.72±0.04). Surface roughness values were higher for microhybrid (1.01±0.27) compared with nanofilled (0.68 ±0.09) and nanohybrid (0.48±0.15) composites when the specimens were not subjects to acid challenge. In the presence of hydrochloric acid, microhybrid (1.26±0.28) and nanofilled (1.18±0,30) composites presents higher surface roughness values compared with nanohybrid (0.77±0.15). The hydrochloric acid affected the surface roughness of composite resin subjected to brushing.

Cheap and fast measuring roughness on big surfaces with an imprint method

Science.gov (United States)

Schopf, C.; Liebl, J.; Rascher, R.

2017-10-01

Roughness, shape and structure of a surface offer information on the state, shape and surface characteristics of a component. Particularly the roughness of the surface dictates the subsequent polishing of the optical surface. The roughness is usually measured by a white light interferometer, which is limited by the size of the components. Using a moulding method of surfaces that are difficult to reach, an imprint is taken and analysed regarding to roughness and structure. This moulding compound method is successfully used in dental technology. In optical production, the moulding compound method is advantageous in roughness determination in inaccessible spots or on large components (astrological optics). The "replica method" has been around in metal analysis and processing. Film is used in order to take an impression of a surface. Then, it is analysed for structures. In optical production, compound moulding seems advantageous in roughness determination in inaccessible spots or on large components (astrological optics). In preliminary trials, different glass samples with different roughness levels were manufactured. Imprints were taken from these samples (based on DIN 54150 "Abdruckverfahren für die Oberflächenprüfung"). The objective of these feasibility tests was to determine the limits of this method (smallest roughness determinable / highest roughness). The roughness of the imprint was compared with the roughness of the glass samples. By comparing the results, the uncertainty of the measuring method was determined. The spectrum for the trials ranged from rough grind (0.8 μm rms), over finishing grind (0.6 μm rms) to polishing (0.1 μm rms).

Surface roughness reduction using spray-coated hydrogen silsesquioxane reflow

DEFF Research Database (Denmark)

Cech, Jiri; Pranov, Henrik; Kofod, Guggi

2013-01-01

Surface roughness or texture is the most visible property of any object, including injection molded plastic parts. Roughness of the injection molding (IM) tool cavity directly affects not only appearance and perception of quality, but often also the function of all manufactured plastic parts. So...... called “optically smooth” plastic surfaces is one example, where low roughness of a tool cavity is desirable. Such tool surfaces can be very expensive to fabricate using conventional means, such as abrasive diamond polishing or diamond turning. We present a novel process to coat machined metal parts...... are reduced 10 and 3 times respectively. We completed more than 10,000 injection molding cycles without detectable degradation of the HSQ coating. This result opens new possibilities for molding of affordable plastic parts with perfect surface finish....

Friction of hydrogels with controlled surface roughness on solid flat substrates.

Science.gov (United States)

Yashima, Shintaro; Takase, Natsuko; Kurokawa, Takayuki; Gong, Jian Ping

2014-05-14

This study investigated the effect of hydrogel surface roughness on its sliding friction against a solid substrate having modestly adhesive interaction with hydrogels under small normal pressure in water. The friction test was performed between bulk polyacrylamide hydrogels of varied surface roughness and a smooth glass substrate by using a strain-controlled rheometer with parallel-plates geometry. At small pressure (normal strain 1.4-3.6%), the flat surface gel showed a poor reproducibility in friction. In contrast, the gels with a surface roughness of 1-10 μm order showed well reproducible friction behaviors and their frictional stress was larger than that of the flat surface hydrogel. Furthermore, the flat gel showed an elasto-hydrodynamic transition while the rough gels showed a monotonous decrease of friction with velocity. The difference between the flat surface and the rough surface diminished with the increase of the normal pressure. These phenomena are associated with the different contact behaviors of these soft hydrogels in liquid, as revealed by the observation of the interface using a confocal laser microscope.

Pheochromocytoma (PC12 Cell Response on Mechanobactericidal Titanium Surfaces

Directory of Open Access Journals (Sweden)

Jason V. Wandiyanto

2018-04-01

Full Text Available Titanium is a biocompatible material that is frequently used for making implantable medical devices. Nanoengineering of the surface is the common method for increasing material biocompatibility, and while the nanostructured materials are well-known to represent attractive substrata for eukaryotic cells, very little information has been documented about the interaction between mammalian cells and bactericidal nanostructured surfaces. In this study, we investigated the effect of bactericidal titanium nanostructures on PC12 cell attachment and differentiation—a cell line which has become a widely used in vitro model to study neuronal differentiation. The effects of the nanostructures on the cells were then compared to effects observed when the cells were placed in contact with non-structured titanium. It was found that bactericidal nanostructured surfaces enhanced the attachment of neuron-like cells. In addition, the PC12 cells were able to differentiate on nanostructured surfaces, while the cells on non-structured surfaces were not able to do so. These promising results demonstrate the potential application of bactericidal nanostructured surfaces in biomedical applications such as cochlear and neuronal implants.

Determination of forest road surface roughness by Kinect depth imaging

Directory of Open Access Journals (Sweden)

Francesco Marinello

2017-12-01

Full Text Available Roughness is a dynamic property of the gravel road surface that affects safety, ride comfort as well as vehicle tyre life and maintenance costs. A rapid survey of gravel road condition is fundamental for an effective maintenance planning and definition of the intervention priorities.Different non-contact techniques such as laser scanning, ultrasonic sensors and photogrammetry have recently been proposed to reconstruct three-dimensional topography of road surface and allow extraction of roughness metrics. The application of Microsoft Kinect™ depth camera is proposed and discussed here for collection of 3D data sets from gravel roads, to be implemented in order to allow quantification of surface roughness.The objectives are to: i verify the applicability of the Kinect sensor for characterization of different forest roads, ii identify the appropriateness and potential of different roughness parameters and iii analyse the correlation with vibrations recoded by 3-axis accelerometers installed on different vehicles. The test took advantage of the implementation of the Kinect depth camera for surface roughness determination of 4 different forest gravel roads and one well-maintained asphalt road as reference. Different vehicles (mountain bike, off-road motorcycle, ATV vehicle, 4WD car and compact crossover were included in the experiment in order to verify the vibration intensity when travelling on different road surface conditions. Correlations between the extracted roughness parameters and vibration levels of the tested vehicles were then verified. Coefficients of determination of between 0.76 and 0.97 were detected between average surface roughness and standard deviation of relative accelerations, with higher values in the case of lighter vehicles.

The biocompatibility of SLA-treated titanium implants

International Nuclear Information System (INIS)

Kim, Hyeongil; Choi, Seong-Ho; Ryu, Jae-Jun; Koh, Seung-Yong; Park, Ju-Han; Lee, In-Seop

2008-01-01

The titanium implant surface was sandblasted with large grits and acid etched (SLA) to increase the implant surface for osseointegration. The topography of the titanium surface was investigated with scanning electron microscopy (SEM) and a profilometer. The SLA implant demonstrated uniform small micro pits (1-2 μm in diameter). The values of average roughness (R a ) and maximum height (R t ) were 1.19 μm and 10.53 μm respectively after sandblasting and the acid-etching treatment. In the cell-surface interaction study, the human osteoblast cells grew well in vitro. The in vivo evaluation of the SLA implant placed in rabbit tibia showed good bone-to-implant contact (BIC) with a mean value of 29% in total length of the implant. In the short-term clinical study, SLA implants demonstrated good clinical performance, maintaining good crestal bone height

The surface nanostructures of titanium alloy regulate the proliferation of endothelial cells

Directory of Open Access Journals (Sweden)

Min Lai

2014-02-01

Full Text Available To investigate the effect of surface nanostructures on the behaviors of human umbilical vein endothelial cells (HUVECs, surface nanostructured titanium alloy (Ti-3Zr2Sn-3Mo-25Nb, TLM was fabricated by surface mechanical attrition treatment (SMAT technique. Field emission scanning electron microscopy (FE-SEM, atomic force microscopy (AFM, transmission electron microscopy (TEM and X-ray diffraction (XRD were employed to characterize the surface nanostructures of the TLM, respectively. The results demonstrated that nano-crystalline structures with several tens of nanometers were formed on the surface of TLM substrates. The HUVECs grown onto the surface nanostructured TLM spread well and expressed more vinculin around the edges of cells. More importantly, HUVECs grown onto the surface nanostructured TLM displayed significantly higher (p < 0.01 or p < 0.05 cell adhesion and viabilities than those of native titanium alloy. HUVECs cultured on the surface nanostructured titanium alloy displayed significantly higher (p < 0.01 or p < 0.05 productions of nitric oxide (NO and prostacyclin (PGI2 than those of native titanium alloy, respectively. This study provides an alternative for the development of titanium alloy based vascular stents.

Surface roughness induced electron mobility degradation in InAs nanowires

International Nuclear Information System (INIS)

Wang Fengyun; Yip, Sen Po; Han, Ning; Fok, KitWa; Lin, Hao; Hou, Jared J; Dong, Guofa; Hung, Tak Fu; Chan, K S; Ho, Johnny C

2013-01-01

In this work, we present a study of the surface roughness dependent electron mobility in InAs nanowires grown by the nickel-catalyzed chemical vapor deposition method. These nanowires have good crystallinity, well-controlled surface morphology without any surface coating or tapering and an excellent peak field-effect mobility up to 15 000 cm 2 V −1 s −1 when configured into back-gated field-effect nanowire transistors. Detailed electrical characterizations reveal that the electron mobility degrades monotonically with increasing surface roughness and diameter scaling, while low-temperature measurements further decouple the effects of surface/interface traps and phonon scattering, highlighting the dominant impact of surface roughness scattering on the electron mobility for miniaturized and surface disordered nanowires. All these factors suggest that careful consideration of nanowire geometries and surface condition is required for designing devices with optimal performance. (paper)

In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment

International Nuclear Information System (INIS)

Zhang, E W; Wang, Y B; Zheng, Y F; Shuai, K G; Gao, F; Bai, Y J; Cheng, Y; Xiong, X L; Wei, S C

2011-01-01

The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability.

In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment

Energy Technology Data Exchange (ETDEWEB)

Zhang, E W; Wang, Y B; Zheng, Y F [State Key Laboratory for Turbulence and Complex System, Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Shuai, K G; Gao, F; Bai, Y J; Cheng, Y; Xiong, X L [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wei, S C, E-mail: enwei@pku.edu.cn, E-mail: yanbo.pku@pku.edu.cn, E-mail: shuaikegang@gmail.com, E-mail: soarfgoal@gmail.com, E-mail: norice86@163.com, E-mail: chengyan@pku.edu.cn, E-mail: xxiaoling11@hotmail.com, E-mail: yfzheng@pku.edu.cn, E-mail: weishicheng99@163.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University, Beijing 100081 (China)

2011-04-15

The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability.

The VHCF experimental investigation of FV520B-I with surface roughness Ry

Science.gov (United States)

Wang, J. L.; Zhang, Y. L.; Ding, M. C.; Zhao, Q. C.

2018-05-01

Different surface roughness type (Ra and Ry) has different effect on the VHCF failure and life. Ra is widely employed as the quantitative expression of the surface roughness, but there are few fatigue failure mechanism analysis and experimental study under surface roughness Ry. The VHCF experiment is conducted out using the specimen with different surface roughness values. The surface roughness Ry is employed as the major research object to investigate the relationship and distribution tendency between the Ry, fatigue life and the distance between internal inclusion and surface, and a new VHCF failure character is proposed.

Radiation properties modeling for plasma-sprayed-alumina-coated rough surfaces for spacecrafts

International Nuclear Information System (INIS)

Li, R.M.; Joshi, Sunil C.; Ng, H.W.

2006-01-01

Spacecraft thermal control materials (TCMs) play a vital role in the entire service life of a spacecraft . Most of the conventional TCMs degrade in the harmful space environment . In the previous study, plasma sprayed alumina (PSA) coating was established as a new and better TCM for spacecrafts, in view of its stability and reliability compared to the traditional TCMs . During the investigation, the surface roughness of PSA was found important, because the roughness affects the radiative heat exchange between the surface and its surroundings. Parameters such as root-mean-square roughness cannot properly evaluate surface roughness effects on radiative properties of opaque surfaces . Some models have been developed earlier to predict the effects, such as Davies' model , Tang and Buckius's statistical geometric optics model . However, they are valid only in their own specific situations. In this paper, an energy absorption geometry model was developed and applied to investigate the roughness effects with the help of 2D surface profile of PSA coated substrate scanned at micron level. This model predicts effective normal solar absorptance (α ne ) and effective hemispherical infrared emittance (ε he ) of a rough PSA surface. These values, if used in the heat transfer analysis of an equivalent, smooth and optically flat surface, lead to the prediction of the same rate of heat exchange and temperature as that of for the rough PSA surface. The model was validated through comparison between a smooth and a rough PSA coated surfaces. Even though not tested for other types of materials, the model formulation is generic and can be used to incorporate the rough surface effects for other types of thermal coatings, provided the baseline values of normal solar absorptance (α n ) and hemispherical infrared emittance (ε h ) are available for a generic surface of the same material

Titanium-based spectrally selective surfaces for solar thermal systems

Energy Technology Data Exchange (ETDEWEB)

Wilson, A D; Holmes, J P

1983-10-01

A study of spectrally selective surfaces based on anodic oxide films on titanium is presented. These surfaces have low values of solar absorptance, 0.77, due to the nonideal optical properties of the anodic TiO2 for antireflection of titanium. A simple chemical etching process is described which gives a textured surface with dimensions similar to the wavelengths of solar radiation, leading to spectral selectivity. The performance of this dark-etched surface can be further improved by anodising, and optimum absorbers have been produced with alpha(s) 0.935 and hemispherical emittances (400 K) 0.23. The surface texturing effects a significant improvement in alpha(s) at oblique incidence.

Computer simulation of RBS spectra from samples with surface roughness

Energy Technology Data Exchange (ETDEWEB)

Malinský, P., E-mail: malinsky@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J. E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Hnatowicz, V., E-mail: hnatowicz@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Macková, A., E-mail: mackova@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J. E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic)

2016-03-15

A fast code for the simulation of common RBS spectra including surface roughness effects has been written and tested on virtual samples comprising either a rough layer deposited on a smooth substrate or smooth layer deposited on a rough substrate and simulated at different geometries. The sample surface or interface relief has been described by a polyline and the simulated RBS spectrum has been obtained as the sum of many particular spectra from randomly chosen particle trajectories. The code includes several procedures generating virtual samples with random and regular (periodical) roughness. The shape of the RBS spectra has been found to change strongly with increasing sample roughness and an increasing angle of the incoming ion beam.

Turbulent lubrication theory considering the surface roughness effects, 2

International Nuclear Information System (INIS)

Hashimoto, Hiromu; Wada, Sanae; Kobayashi, Toshinobu.

1990-01-01

This second paper describes an application of the generalized turbulent lubrication theory considering the surface roughness effects, which is developed in the previous paper, to the finite-width journal bearings. In the numerical analysis, the nonlinear equations for the modified turbulence coefficients are simplified to save a computation time within a satisfactory accuracy under the assumption that the shear flow is superior to the pressure flow in the turbulent lubrication films. The numerical results of pressure distribution, Sommerfeld number, attitude angle, friction coefficient and flow rate for the Reynolds number of Re=2000, 5000 and 10000 are indicated in graphic form for various values of relative roughness, and the effects of surface roughness on these static performance characteristics are discussed. Moreover, the eccentricity ratio and attitude angle of the journal bearings with homogeneous rough surface are obtained experimentally for a wide range of Sommerfeld number, and the experimental results are compared with theoretical results. (author)

Machinability evaluation of titanium alloys.

Science.gov (United States)

Kikuchi, Masafumi; Okuno, Osamu

2004-03-01

In the present study, the machinability of titanium, Ti-6Al-4V, Ti-6A1-7Nb, and free-cutting brass was evaluated using a milling machine. The metals were slotted with square end mills under four cutting conditions. The cutting force and the rotational speed of the spindle were measured. The cutting forces for Ti-6Al-4V and Ti-6Al-7Nb were higher and that for brass was lower than that for titanium. The rotational speed of the spindle was barely affected by cutting. The cross sections of the Ti-6Al-4V and Ti-6Al-7Nb chips were more clearly serrated than those of titanium, which is an indication of difficult-to-cut metals. There was no marked difference in the surface roughness of the cut surfaces among the metals. Cutting force and the appearance of the metal chips were found to be useful as indices of machinability and will aid in the development of new alloys for dental CAD/CAM and the selection of suitable machining conditions.

Surface roughness retrieval by inversion of the Hapke model: A multiscale approach

Science.gov (United States)

Labarre, S.; Ferrari, C.; Jacquemoud, S.

2017-07-01

Surface roughness is a key property of soils that controls many surface processes and influences the scattering of incident electromagnetic waves at a wide range of scales. Hapke (2012b) designed a photometric model providing an approximate analytical solution of the Bidirectional Reflectance Distribution Function (BRDF) of a particulate medium: he introduced the effect of surface roughness as a correction factor of the BRDF of a smooth surface. This photometric roughness is defined as the mean slope angle of the facets composing the surface, integrated over all scales from the grain size to the local topography. Yet its physical meaning is still a question at issue, as the scale at which it occurs is not clearly defined. This work aims at better understanding the relative influence of roughness scales on soil BRDF and to test the ability of the Hapke model to retrieve a roughness that depicts effectively the ground truth. We apply a wavelet transform on millimeter digital terrain models (DTM) acquired over volcanic terrains. This method allows splitting the frequency band of a signal in several sub-bands, each corresponding to a spatial scale. We demonstrate that sub-centimeter surface features dominate both the integrated roughness and the BRDF shape. We investigate the suitability of the Hapke model for surface roughness retrieval by inversion on optical data. A global sensitivity analysis of the model shows that soil BRDF is very sensitive to surface roughness, nearly as much as the single scattering albedo according to the phase angle, but also that these two parameters are strongly correlated. Based on these results, a simplified two-parameter model depending on surface albedo and roughness is proposed. Inversion of this model on BRDF data simulated by a ray-tracing code over natural targets shows a good estimation of surface roughness when the assumptions of the model are verified, with a priori knowledge on surface albedo.

Qualitative internal surface roughness classification using acoustic emission

International Nuclear Information System (INIS)

Mohd Hafizi Zohari; Mohd Hanif Saad

2009-04-01

This paper describes a novel new nondestructive method of qualitative internal surface roughness classification for pipes utilizing Acoustic Emission (AE) signal. Two different flowrate are introduced in a pipe obstructed using normally available components (e.g.: valve). The AE signal at suitable location from the obstruction are obtained and the peak amplitudes, RMS amplitude and energy of the AE signal are obtained. A dimensionless number, the Bangi Number, AB, is then calculated as a ratio of the AE parameters (peak amplitude, RMS amplitude or energy) in low flowrate measurement compared to the AE parameters in high flowrate measurement. It was observed that the Bangi Number, AB obtained can then be used to successfully discriminate between rough and smooth internal surface roughness. (author)

Surface roughness characterization of cast components using 3D optical methods

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Tiedje, Niels Skat; Hansen, Hans Nørgaard

scanning probe image processor (SPIP) software and the results of the surface roughness parameters obtained were subjected to statistical analyses. The bearing area ratio was introduced and applied to the surface roughness analysis. From the results, the surface quality of the standard comparators...... is successfully characterised and it was established that the areal parameters are more informative for sand cast components. The roughness values of the standard visual comparators can serve as a control for the cast components and for order specifications in the foundry industry. A series of iron castings were...... made in green sand moulds and the surface roughness parameter (Sa) values were compared with those of the standards. Sa parameter suffices for the evaluation of casting surface texture. The S series comparators showed a better description of the surface of castings after shot blasting than the A series...

Spin Hall effect by surface roughness

KAUST Repository

Zhou, Lingjun; Grigoryan, Vahram L.; Maekawa, Sadamichi; Wang, Xuhui; Xiao, Jiang

2015-01-01

induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.

Elastic–plastic adhesive contact of non-Gaussian rough surfaces

Indian Academy of Sciences (India)

Adhesion; asymmetric roughness; elastic–plastic contact; non-Gaussian rough surfaces. ... model of contact deformation that is based on accurate Finite Element Analysis (FEA) of an elastic–plastic single asperity contact. ... Sadhana | News.

Investigation of surface roughness on etched glass surfaces

International Nuclear Information System (INIS)

Papa, Z.; Budai, J.; Farkas, B.; Toth, Z.

2011-01-01

Roughening the surface of solar cells is a common practice within the photovoltaic industry as it reduces reflectance, and thus enhances the performance of devices. In this work the relationship between reflectance characterized by the haze parameter, surface roughness and optical properties was investigated. To achieve this goal, model samples were prepared by hydrofluoric acid etching of glass for various times and measured by optical microscopy, spectroscopic ellipsometry, scanning electron microscopy, and atomic force microscopy. Our investigation showed that the surface reflectance was decreased not only by the roughening of the surface but also by the modification of the depth profile and lowering of the refractive index of the surface domain of the samples.

Effect of Nanosheet Surface Structure of Titanium Alloys on Cell Differentiation

Directory of Open Access Journals (Sweden)

Satoshi Komasa

2014-01-01

Full Text Available Titanium alloys are the most frequently used dental implants partly because of the protective oxide coating that spontaneously forms on their surface. We fabricated titania nanosheet (TNS structures on titanium surfaces by NaOH treatment to improve bone differentiation on titanium alloy implants. The cellular response to TNSs on Ti6Al4V alloy was investigated, and the ability of the modified surfaces to affect osteogenic differentiation of rat bone marrow cells and increase the success rate of titanium implants was evaluated. The nanoscale network structures formed by alkali etching markedly enhanced the functions of cell adhesion and osteogenesis-related gene expression of rat bone marrow cells. Other cell behaviors, such as proliferation, alkaline phosphatase activity, osteocalcin deposition, and mineralization, were also markedly increased in TNS-modified Ti6Al4V. Our results suggest that titanium implants modified with nanostructures promote osteogenic differentiation, which may improve the biointegration of these implants into the alveolar bone.

Surface roughness of orthodontic band cements with different compositions

Directory of Open Access Journals (Sweden)

Françoise Hélène van de Sande

2011-06-01

Full Text Available OBJECTIVES: The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. MATERIAL AND METHODS: Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP, compomer (C, resin-modified glass ionomer cement (RMGIC and resin cement (RC. Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0 or 0.1 M lactic acid solution (pH 4.0 for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200 before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions or paired t-test (comparison before and after the storage period at 5% significance level. RESULTS: The values for average surface roughness were statistically different (pRMGIC>C>R (p0.05. Compared to the current threshold (0.2 µm related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. CONCLUSIONS: Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.

Histomorphometric and histologic evaluation of titanium-zirconium (aTiZr) implants with anodized surfaces.

Science.gov (United States)

Sharma, Ajay; McQuillan, A James; Shibata, Yo; Sharma, Lavanya A; Waddell, John Neil; Duncan, Warwick John

2016-05-01

The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, atomic force microscopy and goniometry. Forty implant discs with thickness of 1.5 and 10 mm diameter (10 of each-titanium, titanium-zirconium, anodized titanium and anodized titanium-zirconium) were placed in the femoral condyles of 10 sheep. Histomorphometric and histologic analysis were performed 4 weeks after implantation. The anodized implants displayed hydrophilic, porous, nano-to-micrometer scale roughened surfaces. Energy dispersive spectroscopy analysis revealed calcium and phosphorous incorporation into the surface of both titanium and titanium-zirconium after anodization. Histologically there was new bone apposition on all implanted discs, slightly more pronounced on anodised discs. The percentage bone-to-implant contact measurements of anodized implants were higher than machined/unmodified implants but there was no significant difference between the two groups with anodized surfaces (P > 0.05, n = 10). The present histomorphometric and histological findings confirm that surface modification of titanium-zirconium by anodization is similar to anodised titanium enhances early osseointegration compared to machined implant surfaces.

Human Mesenchymal Stem Cell Morphology and Migration on Micro-Textured Titanium

Directory of Open Access Journals (Sweden)

Brittany eBanik

2016-05-01

Full Text Available The implant used in spinal fusion procedures is an essential component to achieving successful arthrodesis. At the cellular level, the implant impacts healing and fusion through a series of steps: first, mesenchymal stem cells (MSCs need to adhere and proliferate to cover the implant; second, the MSCs must differentiate into osteoblasts; third, the osteoid matrix produced by the osteoblasts needs to generate new bone tissue, thoroughly integrating the implant with the vertebrate above and below. Previous research has demonstrated that micro-textured titanium is advantageous over smooth titanium and PEEK implants for both promoting osteogenic differentiation and integrating with host bone tissue; however, no investigation to date has examined the early morphology and migration of MSCs on these surfaces. This study details cell spreading and morphology changes over 24 hours, rate and directionality of migration 6 to 18 hours post seeding, differentiation markers at 10 days, and the long term morphology of MSCs at 7 days, on micro-textured, acid-etched titanium (Endoskeleton, smooth titanium, and smooth PEEK surfaces. The results demonstrate in all metrics, the two titanium surfaces outperformed the PEEK surface. Furthermore, the rough acid-etched titanium surface presented the most favorable overall results, demonstrating the random migration needed to efficiently cover a surface in addition to morphologies consistent with osteoblasts and preosteoblasts.

The promotion of osseointegration of titanium surfaces by coating with silk protein sericin.

Science.gov (United States)

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.

Investigation and modelling of rubber stationary friction on rough surfaces

International Nuclear Information System (INIS)

Le Gal, A; Klueppel, M

2008-01-01

This paper presents novel aspects regarding the physically motivated modelling of rubber stationary sliding friction on rough surfaces. The description of dynamic contact is treated within the framework of a generalized Greenwood-Williamson theory for rigid/soft frictional pairings. Due to the self-affinity of rough surfaces, both hysteresis and adhesion friction components arise from a multi-scale excitation of surface roughness. Beside a complete analytical formulation of contact parameters, the morphology of macrotexture is considered via the introduction of a second scaling range at large length scales which mostly contribute to hysteresis friction. Moreover, adhesion friction is related to the real area of contact combined with the kinetics of interfacial peeling effects. Friction experiments carried out with different rubbers on rough granite and asphalt point out the relevance of hysteresis and adhesion friction concepts on rough surfaces. The two scaling ranges approach significantly improves the description of wet and dry friction behaviour within the range of low sliding velocity. In addition, material and surface effects are predicted and understood on a physical basis. The applicability of such modelling is of high interest for materials developers and road constructors regarding the prediction of wet grip performance of tyres on road tracks

Investigation and modelling of rubber stationary friction on rough surfaces

Energy Technology Data Exchange (ETDEWEB)

Le Gal, A; Klueppel, M [Deutsches Institut fuer Kautschuktechnologie, Eupener Strasse 33, D-30519 Hannover (Germany)

2008-01-09

This paper presents novel aspects regarding the physically motivated modelling of rubber stationary sliding friction on rough surfaces. The description of dynamic contact is treated within the framework of a generalized Greenwood-Williamson theory for rigid/soft frictional pairings. Due to the self-affinity of rough surfaces, both hysteresis and adhesion friction components arise from a multi-scale excitation of surface roughness. Beside a complete analytical formulation of contact parameters, the morphology of macrotexture is considered via the introduction of a second scaling range at large length scales which mostly contribute to hysteresis friction. Moreover, adhesion friction is related to the real area of contact combined with the kinetics of interfacial peeling effects. Friction experiments carried out with different rubbers on rough granite and asphalt point out the relevance of hysteresis and adhesion friction concepts on rough surfaces. The two scaling ranges approach significantly improves the description of wet and dry friction behaviour within the range of low sliding velocity. In addition, material and surface effects are predicted and understood on a physical basis. The applicability of such modelling is of high interest for materials developers and road constructors regarding the prediction of wet grip performance of tyres on road tracks.

Temperature effect on surface oxidation of titanium

International Nuclear Information System (INIS)

Vaquilla, I.; Barco, J.L. del; Ferron, J.

1990-01-01

The effect of temperature on the first stages of the superficial oxidation of polycrystalline titanium was studied using both Auger electron spectroscopy (AES) and emission shreshold (AEAPS). The number of compounds present on the surface was determined by application of the factor analysis technique. Reaction evolution was followed through the relative variation of Auger LMM and LMV transitions which are characteristic of titanium. Also the evolution of the chemical shift was determined by AEAPS. The amount of oxygen on the surface was quantified using transition KLL of oxygen. It was found that superficial oxidation depends on temperature. As much as three different compounds were determined according to substrate temperature and our exposure ranges. (Author). 7 refs., 5 figs

Symmetric and asymmetric capillary bridges between a rough surface and a parallel surface.

Science.gov (United States)

Wang, Yongxin; Michielsen, Stephen; Lee, Hoon Joo

2013-09-03

Although the formation of a capillary bridge between two parallel surfaces has been extensively studied, the majority of research has described only symmetric capillary bridges between two smooth surfaces. In this work, an instrument was built to form a capillary bridge by squeezing a liquid drop on one surface with another surface. An analytical solution that describes the shape of symmetric capillary bridges joining two smooth surfaces has been extended to bridges that are asymmetric about the midplane and to rough surfaces. The solution, given by elliptical integrals of the first and second kind, is consistent with a constant Laplace pressure over the entire surface and has been verified for water, Kaydol, and dodecane drops forming symmetric and asymmetric bridges between parallel smooth surfaces. This solution has been applied to asymmetric capillary bridges between a smooth surface and a rough fabric surface as well as symmetric bridges between two rough surfaces. These solutions have been experimentally verified, and good agreement has been found between predicted and experimental profiles for small drops where the effect of gravity is negligible. Finally, a protocol for determining the profile from the volume and height of the capillary bridge has been developed and experimentally verified.

Titanium Matrix Composite Ti/TiN Produced by Diode Laser Gas Nitriding

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Aleksander Lisiecki

2015-01-01

Full Text Available A high power direct diode laser, emitting in the range of near infrared radiation at wavelength 808–940 nm, was applied to produce a titanium matrix composite on a surface layer of titanium alloy Ti6Al4V by laser surface gas nitriding. The nitrided surface layers were produced as single stringer beads at different heat inputs, different scanning speeds, and different powers of laser beam. The influence of laser nitriding parameters on the quality, shape, and morphology of the surface layers was investigated. It was found that the nitrided surface layers consist of titanium nitride precipitations mainly in the form of dendrites embedded in the titanium alloy matrix. The titanium nitrides are produced as a result of the reaction between molten Ti and gaseous nitrogen. Solidification and subsequent growth of the TiN dendrites takes place to a large extent at the interface of the molten Ti and the nitrogen gas atmosphere. The direction of TiN dendrites growth is perpendicular to the surface of molten Ti. The roughness of the surface layers depends strongly on the heat input of laser nitriding and can be precisely controlled. In spite of high microhardness up to 2400 HV0.2, the surface layers are crack free.

Effects of thickness and surface roughness on mechanical properties of aluminum sheets

International Nuclear Information System (INIS)

Suh, Chang Hee; Jung, Yun Chul; Kim, Young Suk

2010-01-01

The effect of thickness on the mechanical properties of Al 6K21-T4 sheet specimens under uniaxial tension was investigated. In order to reduce the thickness of the specimens without changing the microstructure and grain size, chemical etching was carried out, resulting in Al sheets ranging from 0.40 mm to 1.58 mm in thickness. Additionally, the effect of surface roughness was determined by finite element (FE) calculations performed using FE code MARC 2007. Tensile specimens of varying surface roughness were modeled and simulated. An analysis of the combined effects of the thickness and surface roughness revealed that the yield and tensile strengths decreased when the number of grains over the thickness was decreased. The ductility also decreased when reducing the thickness. An FE simulation showed that both the surface roughness and thickness affected the flow-curve shape. Moreover, the effect of the surface roughness tended to increase when decreasing the sheet thickness of specimens having the same roughness

Effect of Superhydrophobic Surface of Titanium on Staphylococcus aureus Adhesion

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Peifu Tang

2011-01-01

Full Text Available Despite the systemic antibiotics prophylaxis, orthopedic implants still remain highly susceptible to bacterial adhesion and resulting in device-associated infection. Surface modification is an effective way to decrease bacterial adhesion. In this study, we prepared surfaces with different wettability on titanium surface based on TiO2 nanotube to examine the effect of bacterial adhesion. Firstly, titanium plates were calcined to form hydrophilic TiO2 nanotube films of anatase phase. Subsequently, the nanotube films and inoxidized titaniums were treated with 1H, 1H, 2H, 2H-perfluorooctyl-triethoxysilane (PTES, forming superhydrophobic and hydrophobic surfaces. Observed by SEM and contact angle measurements, the different surfaces have different characteristics. Staphylococcus aureus (SA adhesion on different surfaces was evaluated. Our experiment results show that the superhydrophobic surface has contact angles of water greater than 150∘ and also shows high resistance to bacterial contamination. It is indicated that superhydrophobic surface may be a factor to reduce device-associated infection and could be used in clinical practice.

Superficial characterization of titanium league when submitted to abrasive blasting; Caracterizacao superficial de titanio liga ao ser submetido a tratamento de jateamento

Energy Technology Data Exchange (ETDEWEB)

Suzuki, L.Y.; Leite, I.V.; Szesz, E.M.; Siqueira, C.J.M., E-mail: lsuzuki@neoortho.com.b [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

2010-07-01

Commercially pure titanium and some of its alloys exhibit a good biocompatibility. These characteristics are frequently used in the manufacture of orthopedic and dental implants. It is possible to modify its surface making it the bioactive using various methods, such as deposition of hydroxyapatite by plasma spray and increasing the roughness of the surface by abrasive blasting. This work is to modify the surface of titanium alloy Ti6Al4V ELI (ASTM F136: 02a) for abrasive blasting and study the morphology, crystallographic phases and the mechanical characteristics of the surface obtained. For such purpose, SEM images, diffraction of X-rays and tests of risk produced by nanoindenter. The sandblasting was done using alumina powder and blasting time of 6s. The morphology of the surfaces of Ti6Al4V ELI changed after sandblasting with increased roughness. It is possible to conclude that after sandblasting the titanium surface do not have a ductile behavior. (author)

Biocompatibility assessment of spark plasma-sintered alumina-titanium cermets.

Science.gov (United States)

Guzman, Rodrigo; Fernandez-García, Elisa; Gutierrez-Gonzalez, Carlos F; Fernandez, Adolfo; Lopez-Lacomba, Jose Luis; Lopez-Esteban, Sonia

2016-01-01

Alumina-titanium materials (cermets) of enhanced mechanical properties have been lately developed. In this work, physical properties such as electrical conductivity and the crystalline phases in the bulk material are evaluated. As these new cermets manufactured by spark plasma sintering may have potential application for hard tissue replacements, their biocompatibility needs to be evaluated. Thus, this research aims to study the cytocompatibility of a novel alumina-titanium (25 vol. % Ti) cermet compared to its pure counterpart, the spark plasma sintered alumina. The influence of the particular surface properties (chemical composition, roughness and wettability) on the pre-osteoblastic cell response is also analyzed. The material electrical resistance revealed that this cermet may be machined to any shape by electroerosion. The investigated specimens had a slightly undulated topography, with a roughness pattern that had similar morphology in all orientations (isotropic roughness) and a sub-micrometric average roughness. Differences in skewness that implied valley-like structures in the cermet and predominance of peaks in alumina were found. The cermet presented a higher surface hydrophilicity than alumina. Any cytotoxicity risk associated with the new materials or with the innovative manufacturing methodology was rejected. Proliferation and early-differentiation stages of osteoblasts were statistically improved on the composite. Thus, our results suggest that this new multifunctional cermet could improve current alumina-based biomedical devices for applications such as hip joint replacements. © The Author(s) 2015.

Correlation between Surface Roughness Characteristics in CO2 Laser Cutting of Mild Steel

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M. Radovanović

2012-12-01

Full Text Available CO2 laser oxygen cutting of mild steel is widely used industrial application. Cut surface quality is a very important characteristic of laser cutting that ensures an advantage over other contour cutting processes. In this paper mathematical models for estimating characteristics of surface quality such as average surface roughness and ten-point mean roughness in CO2 laser cutting of mild steel based on laser cutting parameters were developed. Empirical models were developed using artificial neural networks and experimental data collected. Taguchi’s orthogonal array was implemented for experimental plan. From the analysis of the developed mathematical models it was observed that functional dependence between laser cutting parameters, their interactions and surface roughness characteristics is complex and non-linear. It was also observed that there exist region of minimal average surface roughness to ten-point mean roughness ratio. The relationship between average surface roughness and ten-point mean roughness was found to be nonlinear and can be expressed with a second degree polynomial.

Tribological Properties of Surface-Textured and Plasma-Nitrided Pure Titanium Under Oil Lubrication Condition

Science.gov (United States)

Zhang, Baosen; Dong, Qiangsheng; Ba, Zhixin; Wang, Zhangzhong; Shi, Hancheng; Xue, Yanting

2018-01-01

Plasma nitriding was conducted as post-treatment for surface texture on pure titanium to obtain a continuous nitriding layer. Supersonic fine particles bombarding (SFPB) was carried out to prepare surface texture. The surface morphologies and chemical composition were analyzed using scanning electron microscope and energy disperse spectroscopy. The microstructures of modified layers were characterized by transmission electron microscope. The tribological properties of surface-textured and duplex-treated pure titanium under oil lubrication condition were systematically investigated in the ball-on-plate reciprocating mode. The effects of applied load and sliding velocity on the tribological behavior were analyzed. The results show that after duplex treatments, the grains size in modified layer becomes slightly larger, and hardness is obviously improved. Wear resistance of duplex-treated pure titanium is significantly improved referenced to untreated and surface-textured pure titanium, which is 3.22 times as much as untreated pure titanium and 2.15 times of that for surface-textured pure titanium, respectively.

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

Science.gov (United States)

Yip, W S; To, S

2018-03-02

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

Modeling and analysis of micro-WEDM process of titanium alloy (Ti–6Al–4V using response surface approach

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P. Sivaprakasam

2014-12-01

Full Text Available Micro-machining technology is effectively used in modern manufacturing industries. This paper investigates the influence of three different input parameters such as voltage, capacitance and feed rate of micro-wire electrical discharge machining (micro-WEDM performances of material removal rate (MRR, Kerf width (KW and surface roughness (SR using response surface methodology with central composite design (CCD. The experiments are carried out on titanium alloy (Ti–6Al–4V. The machining characteristics are significantly influenced by the electrical and non-electrical parameters in micro-WEDM process. Analysis of variance (ANOVA was performed to find out the significant influence of each factor. The model developed can use a genetic algorithm (GA to determine the optimal machining conditions using multi-objective optimization technique. The optimal machining performance of material removal rate, Kerf width and surface roughness are 0.01802 mm3/min, 101.5 μm and 0.789 μm, respectively, using this optimal machining conditions viz. voltage 100 V, capacitance 10 nF and feed rate 15 μm/s.

Electrochemical Characterization of Surface Reactions on Biomedical Titanium alloys

OpenAIRE

Alkhateeb, Emad Hashim

2008-01-01

Titanium and its alloys are successfully used as implant materials for dental, orthopedic and osteosynthesis applications. The processes that take place at the implant tissue interface are important for the acceptance and integration of the implant. This thesis is divided into two parts: the first part deals with surface modification of titanium to improve the osseointegration, and the second part studies metastable pitting of titanium and its alloys. The weakly attached layer of a bone-like ...

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

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Niall Crawford

2016-12-01

Full Text Available Tree frogs need to adhere to surfaces of various roughnesses in their natural habitats; these include bark, leaves and rocks. Rough surfaces can alter the effectiveness of their toe pads, due to factors such as a change of real contact area and abrasion of the pad epithelium. Here, we tested the effect of surface roughness on the attachment abilities of the tree frog Litoria caerulea. This was done by testing shear and adhesive forces on artificial surfaces with controlled roughness, both on single toe pads and whole animal scales. It was shown that frogs can stick 2–3 times better on small scale roughnesses (3–6 µm asperities, producing higher adhesive and frictional forces, but relatively poorly on the larger scale roughnesses tested (58.5–562.5 µm asperities. Our experiments suggested that, on such surfaces, the pads secrete insufficient fluid to fill the space under the pad, leaving air pockets that would significantly reduce the Laplace pressure component of capillarity. Therefore, we measured how well the adhesive toe pad would conform to spherical asperities of known sizes using interference reflection microscopy. Based on experiments where the conformation of the pad to individual asperities was examined microscopically, our calculations indicate that the pad epithelium has a low elastic modulus, making it highly deformable.

Estimation of gloss from rough surface parameters

Science.gov (United States)

Simonsen, Ingve; Larsen, Åge G.; Andreassen, Erik; Ommundsen, Espen; Nord-Varhaug, Katrin

2005-12-01

Gloss is a quantity used in the optical industry to quantify and categorize materials according to how well they scatter light specularly. With the aid of phase perturbation theory, we derive an approximate expression for this quantity for a one-dimensional randomly rough surface. It is demonstrated that gloss depends in an exponential way on two dimensionless quantities that are associated with the surface randomness: the root-mean-square roughness times the perpendicular momentum transfer for the specular direction, and a correlation function dependent factor times a lateral momentum variable associated with the collection angle. Rigorous Monte Carlo simulations are used to access the quality of this approximation, and good agreement is observed over large regions of parameter space.

Tribological Characteristic of Titanium Alloy Surface Layers Produced by Diode Laser Gas Nitriding

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Lisiecki A.

2016-06-01

Full Text Available In order to improve the tribological properties of titanium alloy Ti6Al4V composite surface layers Ti/TiN were produced during laser surface gas nitriding by means of a novel high power direct diode laser with unique characteristics of the laser beam and a rectangular beam spot. Microstructure, surface topography and microhardness distribution across the surface layers were analyzed. Ball-on-disk tests were performed to evaluate and compare the wear and friction characteristics of surface layers nitrided at different process parameters, base metal of titanium alloy Ti6Al4V and also the commercially pure titanium. Results showed that under dry sliding condition the commercially pure titanium samples have the highest coefficient of friction about 0.45, compared to 0.36 of titanium alloy Ti6Al4V and 0.1-0.13 in a case of the laser gas nitrided surface layers. The volume loss of Ti6Al4V samples under such conditions is twice lower than in a case of pure titanium. On the other hand the composite surface layer characterized by the highest wear resistance showed almost 21 times lower volume loss during the ball-on-disk test, compared to Ti6Al4V samples.

Determining the surface roughness coefficient by 3D Scanner

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Karmen Fifer Bizjak

2010-12-01

Full Text Available Currently, several test methods can be used in the laboratory to determine the roughness of rock joint surfaces.However, true roughness can be distorted and underestimated by the differences in the sampling interval of themeasurement methods. Thus, these measurement methods produce a dead zone and distorted roughness profiles.In this paper a new rock joint surface roughness measurement method is presented, with the use of a camera-typethree-dimensional (3D scanner as an alternative to current methods. For this study, the surfaces of ten samples oftuff were digitized by means of a 3D scanner, and the results were compared with the corresponding Rock JointCoefficient (JRC values. Up until now such 3D scanner have been mostly used in the automotive industry, whereastheir use for comparison with obtained JRC coefficient values in rock mechanics is presented here for the first time.The proposed new method is a faster, more precise and more accurate than other existing test methods, and is apromising technique for use in this area of study in the future.

Roughness modification of surfaces treated by a pulsed dielectric barrier discharge

CERN Document Server

Dumitrascu, N; Apetroaei, N; Popa, G

2002-01-01

Local modifications of surface roughness are very important in many applications, as this surface property is able to generate new mechano-physical characteristics of a large category of materials. Roughness is one of the most important parameters used to characterize and control the surface morphology, and techniques that allow modifying and controlling the surface roughness present increasing interest. In this respect we propose the dielectric barrier discharge (DBD) as a simple and low cost method that can be used to induce controlled roughness on various surfaces in the nanoscale range. DBD is produced in helium, at atmospheric pressure, by a pulsed high voltage, 28 kV peak to peak, 13.5 kHz frequency and 40 W power. This type of discharge is a source of energy capable of modifying the physico-chemical properties of the surfaces without affecting their bulk properties. The discharge is characterized by means of electrical probes and, in order to analyse the heat transfer rate from the discharge to the tre...

Scattering from a PEC Slightly Rough Surface in Chiral Media

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Haroon Akhtar Qureshi

2018-01-01

Full Text Available The scattering of left circularly polarized wave from a perfectly electric conducting (PEC rough surface in isotropic chiral media is investigated. Since a slightly rough interface is assumed, the solution is obtained using perturbation method. Zeroth-order term corresponds to solution for a flat interface which helps in making a comparison with the results reported in the literature. First-order term gives the contribution from the surface perturbations, and it is used to define incoherent bistatic scattering coefficients for a Gaussian rough surface. Higher order solution is obtained in a recursive manner. Numerical results are reported for different values of chirality, correlation length, and rms height of the surface. Diffraction efficiency is defined for a sinusoidal grating.

Finite element method analysis of surface roughness transfer in micro flexible rolling

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Qu Feijun

2016-01-01

Full Text Available Micro flexible rolling aims to fabricate submillimeter thick strips with varying thickness profile, where the surface quality of products is mainly determined by initial workpiece surface roughness and subsequent surface asperity flattening process, which is affected by process parameters during rolling. This paper shows a 3D finite element model for flexible rolling of a 250 μm thick workpiece with reduction of 20 to 50%, and rolling phase with thinner thickness indicates a better ability to decrease the surface roughness. Four types of initial workpiece surface roughness are studied in the simulation, and the influences of process parameters, such as friction coefficient, rolling speed and roll gap adjusting speed, on surface asperity flattening of workpieces with different initial surface roughness have been numerically investigated and analysed.

Multipoint contact modeling of nanoparticle manipulation on rough surface

Energy Technology Data Exchange (ETDEWEB)

Zakeri, M., E-mail: m.zakeri@tabrizu.ac.ir; Faraji, J.; Kharazmi, M. [University of Tabriz, School of Engineering Emerging Technologies (Iran, Islamic Republic of)

2016-12-15

In this paper, the atomic force microscopy (AFM)-based 2-D pushing of nano/microparticles investigated on rough substrate by assuming a multipoint contact model. First, a new contact model was extracted and presented based on the geometrical profiles of Rumpf, Rabinovich and George models and the contact mechanics theories of JKR and Schwartz, to model the adhesion forces and the deformations in the multipoint contact of rough surfaces. The geometry of a rough surface was defined by two main parameters of asperity height (size of roughness) and asperity wavelength (compactness of asperities distribution). Then, the dynamic behaviors of nano/microparticles with radiuses in range of 50–500 nm studied during their pushing on rough substrate with a hexagonal or square arrangement of asperities. Dynamic behavior of particles were simulated and compared by assuming multipoint and single-point contact schemes. The simulation results show that the assumption of multipoint contact has a considerable influence on determining the critical manipulation force. Additionally, the assumption of smooth surfaces or single-point contact leads to large error in the obtained results. According to the results of previous research, it anticipated that a particles with the radius less than about 550 nm start to slide on smooth substrate; but by using multipoint contact model, the predicted behavior changed, and particles with radii of smaller than 400 nm begin to slide on rough substrate for different height of asperities, at first.

Geometrical properties of rough metallic surfaces and their implication in electromagnetic problems

International Nuclear Information System (INIS)

Hernandez, A.; Chicon, R.; Ortuno, M.; Abellan, J.

1987-01-01

We analyze the geometrical properties and their implications in the effective surface resistance and wall losses of rough metallic surfaces. The power spectrum and the autocorrelation function are calculated for a simple model that adequately represent the rough surface. The roughness parameters are obtained through average values of the roughness and its derivative. We calculate the density profile, directly related to the depth-dependent effective conductivity. The data from the profilometer are corrected to take into account the finite size of the tip. (author)

Difference in surface reactions between titanium and zirconium in Hanks' solution to elucidate mechanism of calcium phosphate formation on titanium using XPS and cathodic polarization

International Nuclear Information System (INIS)

Tsutsumi, Y.; Nishimura, D.; Doi, H.; Nomura, N.; Hanawa, T.

2009-01-01

Titanium and zirconium were immersed in Hanks' solution with and without calcium and phosphate ions, and the surfaces were characterized with X-ray photoelectron spectroscopy (XPS) to determine the mechanism of calcium phosphate formation on titanium in simulated body fluids and in a living body. In addition, they were cathodically polarized in the above solutions. XPS characterization and cathodic polarization revealed differences in the surface properties in the ability of calcium phosphate formation between titanium and zirconium. The surface oxide film on titanium is not completely oxidized and is relatively reactive; that on zirconium is more passive and protective than that on titanium. Neither calcium nor phosphate stably exists alone on titanium, and calcium phosphate is naturally formed on it; calcium phosphate formed on titanium is stable and protective. On the other hand, calcium is never incorporated on zirconium, while zirconium phosphate, which is easily formed on zirconium, is highly stable and protective. Our study presents new information regarding the surface property of titanium and demonstrates that the characteristics of titanium and zirconium may be applied to various medical devices and new surface modification techniques.

Electromagnetic Scattering from Rough Sea Surface with PM Spectrum Covered by an Organic Film

International Nuclear Information System (INIS)

Wang Rui; Guo Li-Xin; Wang An-Qi; Wu Zhen-Sen

2011-01-01

The rough sea surface covered by an organic film will cause attenuation of capillarity waves, which implies that the organic films play an important role in rough sea surface processes. We focus on a one-dimensional (1D) rough sea surface with the Pierson—Moskowitz (PM) spectrum distributed to the homogeneous insoluble organic slicks. First, the impact of the organic film on the PM surface spectrum is presented, as well as that of the correlation length, the rms height and slope of the rough sea surface. The damping effect of the organic film changes the physical parameters of the rough sea surface. For example, the organic film will reduce the rms height and slopee of the rough sea surface, which results in the attenuation of the high-frequency components of the PM spectrum leading to modification of the surface PM spectrum. Then, the influence of the organic film on the electromagnetic (EM) scattering coefficients from PM rough sea surface covered by the organic film is investigated and discussed in detail, compared with the clean PM rough sea surface through the method of moments. (fundamental areas of phenomenology(including applications))

Dynamic modeling of manipulation of micro/nanoparticles on rough surfaces

International Nuclear Information System (INIS)

Korayem, M.H.; Zakeri, M.

2011-01-01

In this paper, the dynamic behavior of spherical micro/nanoparticles, while being pushed on rough substrates, is studied by means of an Atomic Force Microscope (AFM). For this purpose, first, the contact adhesion force, and the areas and penetration depths of rough surfaces are derived based on the Johnson-Kendall-Roberts (JKR) theory, the Schwarz method, and the Rumpf/Rabinovich models. Then, the dynamic model of particle manipulation on rough substrates is revised using the specified contact theory for rough surfaces. And finally, the pushing of spherical particles with 50, 100, 200, 500, and 10000 nm radii is simulated. The results show that the critical force and the critical time of manipulation decrease when the particles are pushed on the rough surfaces as compared to the smooth ones. It is also observed that the critical force for a rough substrate containing asperities of low height and large radius approaches a comparable critical force magnitude to the smooth substrate, as is expected. Also, when the asperity radius in the substrate is within the range of 0.5 < r < 5 nm, the critical force of pushing decreases; however, as the asperity radius becomes larger than 5 nm, the critical force begins to increase again. Furthermore, the critical values are generally more sensitive to the changes of the asperity radius than the height. It is also found that the difference between the critical values based on the Rumpf and Rabinovich models is negligible. However, the estimation of particles' dynamic behavior using the Rumpf model could be wrong for the rough substrates with small radius asperities, which is considerable in the manipulation and assembly practices. Moreover, the dynamic behavior of particles of small radius (r < 500 nm) change during the pushing process on rough surfaces, and the rolling behavior could be possible on the surfaces that have small radius asperities. The probability of this occurrence is increased in the pushing of larger particles on

Evaluation of surface roughness of the bracket slot floor—a 3D perspective study

Directory of Open Access Journals (Sweden)

Chetankumar O. Agarwal

2016-01-01

Full Text Available Abstract Background An important constituent of an orthodontic appliance is orthodontic brackets. It is either the bracket or the archwire that slides through the bracket slot, during sliding mechanics. Overcoming the friction between the two surfaces demands an important consideration in an appliance design. The present study investigated the surface roughness of four different commercially available stainless steel brackets. Methods All tests were carried out to analyse quantitatively the morphological surface of the bracket slot floor with the help of scanning electron microscope (SEM machine and to qualitatively analyse the average surface roughness (Sa of the bracket slot floor with the help of a three-dimensional (3D non-contact optical surface profilometer machine. Results The SEM microphotographs were evaluated with the help of visual analogue scale, the surface roughness for group A = 0—very rough surface, group C = 1—rough surface, group B = 2—smooth surface, and group D = 3—very smooth surface. Surface roughness evaluation with the 3D non-contact optical surface profilometer machine was highest for group A, followed by group C, group B and group D. Groups B and D provided smooth surface roughness; however, group D had the very smooth surface with values 0.74 and 0.75 for mesial and distal slots, respectively. Conclusions Evaluation of surface roughness of the bracket slot floor with both SEM and profilometer machine led to the conclusion that the average surface roughness was highest for group A, followed by group C, group B and group D.

The effect of surface roughness on the performances of liner-piston ...

African Journals Online (AJOL)

The effect of surface roughness on the performances of liner-piston ring contact in internal combustion engine. ... The surface roughness between the liner and the piston rings, plays an ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

Quantitative roughness characterization of geological surfaces and implications for radar signature analysis

DEFF Research Database (Denmark)

Dierking, Wolfgang

1999-01-01

Stochastic surface models are useful for analyzing in situ roughness profiles and synthetic aperture radar (SAR) images of geological terrain. In this paper, two different surface models are discussed: surfaces with a stationary random roughness (conventional model) and surfaces with a power...

Reproducibility of surface roughness in reaming

DEFF Research Database (Denmark)

Müller, Pavel; De Chiffre, Leonardo

An investigation on the reproducibility of surface roughness in reaming was performed to document the applicability of this approach for testing cutting fluids. Austenitic stainless steel was used as a workpiece material and HSS reamers as cutting tools. Reproducibility of the results was evaluat...

ANFIS Modeling of the Surface Roughness in Grinding Process

OpenAIRE

H. Baseri; G. Alinejad

2011-01-01

The objective of this study is to design an adaptive neuro-fuzzy inference system (ANFIS) for estimation of surface roughness in grinding process. The Used data have been generated from experimental observations when the wheel has been dressed using a rotary diamond disc dresser. The input parameters of model are dressing speed ratio, dressing depth and dresser cross-feed rate and output parameter is surface roughness. In the experimental procedure the grinding conditions...

Role of urban surface roughness in road-deposited sediment build-up and wash-off

Science.gov (United States)

Zhao, Hongtao; Jiang, Qian; Xie, Wenxia; Li, Xuyong; Yin, Chengqing

2018-05-01

Urban road surface roughness is one of the most important factors in estimation of surface runoff loads caused by road-deposited sediment (RDS) wash-off and design of its control measures. However, because of a lack of experimental data to distinguish the role of surface roughness, the effects of surface roughness on RDS accumulation and release are not clear. In this study, paired asphalt and concrete road surfaces and rainfall simulation designs were used to distinguish the role of surface roughness in RDS build-up and wash-off. Our results showed that typical asphalt surfaces often have higher depression depths than typical concrete surfaces, indicating that asphalt surfaces are relatively rougher than concrete surface. Asphalt surfaces can retain a larger RDS amount, relative higher percentage of coarser particles, larger RDS wash-off loads, and lower wash-off percentage, than concrete surfaces. Surface roughness has different effects in RDS motilities with different particle sizes during rainfall runoff, and the settleable particles (44-149 μm) were notably influenced by it. Furthermore, the first flush phenomenon tended to be greater on relatively smooth surfaces than relatively rough surfaces. Overall, surface roughness plays an important role in influencing the complete process of RDS build-up and wash-off on different road characteristics.

Surface Modification of Titanium with Heparin-Chitosan Multilayers via Layer-by-Layer Self-Assembly Technique

International Nuclear Information System (INIS)

Shu, Y.; Zou, J.; Ou, G.; Wang, L.; Li, Q.

2011-01-01

Extracellular matrix (ECM), like biomimetic surface modification of titanium implants, is a promising method for improving its biocompatibility. In this paper chitosan (Chi) and heparin (Hep) multilayer was coated on pure titanium using a layer-by-layer (LbL) self-assembly technique. The Hep-Chi multilayer growth was carried out by first depositing a single layer of positively charged poly-L-lysine (PLL) on the NaOH-treated titanium substrate (negatively charged surface), followed by alternate deposition of negatively charged Hep and positively charged Chi, and terminated by an outermost layer of Chi. The multilayer was characterized by DR-FTIR, SEM, and AFM, and osteoblasts were cocultured with the modified titanium and untreated titanium surfaces, respectively, to evaluate their cytocompatibility in vitro. The results confirmed that Hep-Chi multilayer was fabricated gradually on the titanium surface. The Hep-Chi multilayer-coated titanium improved the adhesion, proliferation and differentiation of osteoblasts. Thus, the approach described here may provide a basis for the preparation of modified titanium surfaces for use in dental or orthopedic implants

Enhancement of Friction against a Rough Surface by a Ridge-Channel Surface Microstructure.

Science.gov (United States)

Bai, Ying; Hui, Chung-Yuen; Levrard, Benjamin; Jagota, Anand

2015-07-14

We report on a study of the sliding friction of elastomeric surfaces patterned with ridges and channels (and unstructured flat controls), against both smooth and roughened spherical indenters. Against the smooth spherical indenter, all of the structured surfaces have highly reduced sliding friction due to the reduction in actual area of contact. Against roughened spherical indenters, however, the sliding force for structured samples can be up to 50% greater than that of an unstructured flat control. The mechanism of enhanced friction against a rough surface is due to a combination of increased actual area of contact, interlocking between roughness and the surface structure, and attendant dynamic instabilities that dissipate energy.

Root surface smoothness or roughness following open debridement. An in vivo study.

Science.gov (United States)

Schlageter, L; Rateitschak-Plüss, E M; Schwarz, J P

1996-05-01

Consensus has not been reached on the desired characteristics of the root surface following cleaning. It is also not clear what degree of roughness or smoothness results from use of different instruments. In the present human clinical study, various instruments for root surface cleaning were evaluated. 18 teeth destined for extraction for periodontal reasons were utilized. After reflection of soft tissue flaps, the 72 root surface aspects of the 18 teeth were uniformally treated with one of the following instruments: Gracey curette (GC), piezo ultrasonic scaler (PUS), Perioplaner curette (PPC), sonic scaler (SS), 75 microns diamond (75 D) and 15 microns diamond (15.D). The degree of roughness of each surface was measured after extraction. A planimetry apparatus was used to establish the average surface roughness (Ra) and the mean depth of the roughness profile (Rz). It was demonstrated that hand- and machine-driven curettes as well as very fine rotating diamonds created the smoothest root surfaces, while "vibrating" instruments such as sonic and ultrasonic scalers, as well as coarse diamonds, tended to roughen the root surface. Whether the root surface should be rough or smooth in order to enhance tissue healing remains an open question.

Surface Roughness of Composite Resins after Simulated Toothbrushing with Different Dentifrices.

Science.gov (United States)

Monteiro, Bruna; Spohr, Ana Maria

2015-07-01

The aim of the study was to evaluate, in vitro, the surface roughness of two composite resins submitted to simulated toothbrushing with three different dentifrices. Totally, 36 samples of Z350XT and 36 samples of Empress Direct were built and randomly divided into three groups (n = 12) according to the dentifrice used (Oral-B Pro-Health Whitening [OBW], Colgate Sensitive Pro-Relief [CS], Colgate Total Clean Mint 12 [CT12]). The samples were submitted to 5,000, 10,000 or 20,000 cycles of simulated toothbrushing. After each simulated period, the surface roughness of the samples was measured using a roughness tester. According to three-way analysis of variance, dentifrice (P = 0.044) and brushing time (P = 0.000) were significant. The composite resin was not significant (P = 0.381) and the interaction among the factors was not significant (P > 0.05). The mean values of the surface roughness (µm) followed by the same letter represent no statistical difference by Tukey's post-hoc test (P composite resins. The dentifrice OBW caused a higher surface roughness in both composite resins.

Surface roughness effects on plasma near a divertor plate and local impact angle

Directory of Open Access Journals (Sweden)

Wanpeng Hu

2017-08-01

Full Text Available The impact of rough surface topography on the electric potential and electric field is generally neglected due to the small scale of surface roughness compared to the width of the plasma sheath. However, the distributions of the electric potential and field on rough surfaces are expected to influence the characteristics of edge plasma and the local impact angle. The distributions of plasma sheath and local impact angle on rough surfaces are investigated by a two dimension-in-space and three dimension-in-velocity (2d3v Particle-In-Cell (PIC code. The influences of the plasma temperature andsurface morphology on the plasma sheath, local impact angle and resulting physical sputtering yield on rough surfaces are investigated.

Influence of polishing on surface roughness following toothbrushing wear of composite resins.

Science.gov (United States)

Dalla-Vecchia, Karine Battestin; Taborda, Talita Damas; Stona, Deborah; Pressi, Heloísa; Burnett Júnior, Luiz Henrique; Rodrigues-Junior, Sinval Adalberto

2017-01-01

This study aimed to evaluate the influence of different polishing systems on the surface roughness of composite resins following procedures to simulate the effects of toothbrushing over time. Four currently available commercial composites were used to make 128 cylindrical specimens. The specimens were randomly allocated to polishing with a 1-step polisher or 1 of 3 multistep polishers (n = 8 per group). The baseline surface roughness was measured, and the specimens were submitted to 5000, 10,000, and 20,000 brushing cycles to represent toothbrushing throughout 6, 12, and 24 months, respectively. Results showed that surface roughness was influenced by the type of composite and polishing system and was not influenced by the simulated toothbrushing time. However, the surface roughness, as challenged by toothbrushing wear, was affected by the interaction among the composite, the polisher, and the toothbrushing time. The 1-step polisher produced the highest surface roughness and influenced toothbrushing wear resistance of some composites.

Adhesion of Porphyromonas gingivalis and Tannerella forsythia to dentin and titanium with sandblasted and acid etched surface coated with serum and serum proteins - An in vitro study.

Science.gov (United States)

Eick, Sigrun; Kindblom, Christian; Mizgalska, Danuta; Magdoń, Anna; Jurczyk, Karolina; Sculean, Anton; Stavropoulos, Andreas

2017-03-01

To evaluate the adhesion of selected bacterial strains incl. expression of important virulence factors at dentin and titanium SLA surfaces coated with layers of serum proteins. Dentin- and moderately rough SLA titanium-discs were coated overnight with human serum, or IgG, or human serum albumin (HSA). Thereafter, Porphyromonas gingivalis, Tannerella forsythia, or a six-species mixture were added for 4h and 24h. The number of adhered bacteria (colony forming units; CFU) was determined. Arg-gingipain activity of P. gingivalis and mRNA expressions of P. gingivalis and T. forsythia proteases and T. forsythia protease inhibitor were measured. Coating specimens never resulted in differences exceeding 1.1 log10 CFU, comparing to controls, irrespective the substrate. Counts of T. forsythia were statistically significantly higher at titanium than dentin, the difference was up to 3.7 log10 CFU after 24h (p=0.002). No statistically significant variation regarding adhesion of the mixed culture was detected between surfaces or among coatings. Arg-gingipain activity of P. gingivalis was associated with log10 CFU but not with the surface or the coating. Titanium negatively influenced mRNA expression of T. forsythia protease inhibitor at 24h (p=0.026 uncoated, p=0.009 with serum). The present findings indicate that: a) single bacterial species (T. forsythia) can adhere more readily to titanium SLA than to dentin, b) low expression of T. forsythia protease inhibitor may influence the virulence of the species on titanium SLA surfaces in comparison with teeth, and c) surface properties (e.g. material and/or protein layers) do not appear to significantly influence multi-species adhesion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of surface roughness and electrokinetic heterogeneity on electroosmotic flow in microchannel

Energy Technology Data Exchange (ETDEWEB)

Masilamani, Kannan; Ganguly, Suvankar; Feichtinger, Christian; Bartuschat, Dominik; Rüde, Ulrich, E-mail: suva_112@yahoo.co.in [Department of Computer Science 10 University of Erlangen-Nuremberg, Cauerstr.11 91058 Erlangen (Germany)

2015-06-15

In this paper, a hybrid lattice-Boltzmann and finite-difference (LB-FD) model is applied to simulate the effects of three-dimensional surface roughness and electrokinetic heterogeneity on electroosmotic flow (EOF) in a microchannel. The lattice-Boltzmann (LB) method has been employed to obtain the flow field and a finite-difference (FD) method is used to solve the Poisson-Boltzmann (PB) equation for the electrostatic potential distribution. Numerical simulation of flow through a square cross-section microchannel with designed roughness is conducted and the results are critically analysed. The effects of surface heterogeneity on the electroosmotic transport are investigated for different roughness height, width, roughness interval spacing, and roughness surface potential. Numerical simulations reveal that the presence of surface roughness changes the nature of electroosmotic transport through the microchannel. It is found that the electroosmotic velocity decreases with the increase in roughness height and the velocity profile becomes asymmetric. For the same height of the roughness elements, the EOF velocity rises with the increase in roughness width. For the heterogeneously charged rough channel, the velocity profile shows a distinct deviation from the conventional plug-like flow pattern. The simulation results also indicate locally induced flow vortices which can be utilized to enhance the flow and mixing within the microchannel. The present study has important implications towards electrokinetic flow control in the microchannel, and can provide an efficient way to design a microfluidic system of practical interest. (paper)

Bidirectional reflectance distribution function modeling of one-dimensional rough surface in the microwave band

International Nuclear Information System (INIS)

Guo Li-Xin; Gou Xue-Yin; Zhang Lian-Bo

2014-01-01

In this study, the bidirectional reflectance distribution function (BRDF) of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Remote measurement of surface roughness, surface reflectance, and body reflectance with LiDAR.

Science.gov (United States)

Li, Xiaolu; Liang, Yu

2015-10-20

Light detection and ranging (LiDAR) intensity data are attracting increasing attention because of the great potential for use of such data in a variety of remote sensing applications. To fully investigate the data potential for target classification and identification, we carried out a series of experiments with typical urban building materials and employed our reconstructed built-in-lab LiDAR system. Received intensity data were analyzed on the basis of the derived bidirectional reflectance distribution function (BRDF) model and the established integration method. With an improved fitting algorithm, parameters involved in the BRDF model can be obtained to depict the surface characteristics. One of these parameters related to surface roughness was converted to a most used roughness parameter, the arithmetical mean deviation of the roughness profile (Ra), which can be used to validate the feasibility of the BRDF model in surface characterizations and performance evaluations.

Effects of different titanium zirconium implant surfaces on initial supragingival plaque formation.

Science.gov (United States)

John, Gordon; Becker, Jürgen; Schwarz, Frank

2017-07-01

The aim of the current study was the evaluation of biofilm development on different implant surfaces. Initial biofilm formation was investigated on five different implant surfaces, machined titanium (MTi), modified machined acid-etched titanium (modMATi), machined titanium zirconium (MTiZr), modified machined and acid-etched titanium zirconium (modMATiZr) and sandblasted large grid and acid-etched titanium zirconium surface (SLATiZr) for 24 and 48 h. Biocompatibility was tested after tooth brushing of the samples via cell viability testing with human gingival fibroblasts. After 24 h of biofilm collection, mean plaque surface was detected in the following descending order: After 24 h: MTiZr > MTi > SLATiZr > modMATiZr > modMATi. Both M surfaces showed significant higher biofilm formation than the other groups. After 48 h: MTiZr > MTi > SLATiZr > modMATiZr > modMATi. After tooth brushing: SLATiZr > modMATi > modMATiZr > MTi > MTiZr. All native samples depicted significant higher cell viability than their corresponding surfaces after biofilm removal procedure. The TiZr groups especially the modMATiZr group showed slower and less biofilm formation. In combination with the good biocompatibility, both modMA surfaces seem to be interesting candidates for surfaces in transgingival implant design. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Improvement of Reactor Fuel Element Heat Transfer by Surface Roughness

Energy Technology Data Exchange (ETDEWEB)

Kjellstroem, B; Larsson, A E

1967-04-15

In heat exchangers with a limited surface temperature such as reactor fuel elements, rough heat transfer surfaces may give lower pumping power than smooth. To obtain data for choice of the most advantageous roughness for the superheater elements in the Marviken reactor, measurements were made of heat transfer and pressure drop in an annular channel with a smooth or rough test rod in a smooth adiabatic shroud. 24 different roughness geometries were tested. The results were transformed to rod cluster geometry by the method of W B Hall, and correlated by the friction and heat transfer similarity laws as suggested by D F Dipprey and R H Sabersky with RMS errors of 12.5 % in the friction factor and 8.1 % in the Stanton number. The relation between the Stanton number and the friction factor could be described by a relation of the type suggested by W Nunner, with a mean error of 3.1 % and an RMS error of 11.6 %. Application of the results to fuel element calculations is discussed, and the great gains in economy which can be obtained with rough surfaces are demonstrated by two examples.

Improvement of Reactor Fuel Element Heat Transfer by Surface Roughness

International Nuclear Information System (INIS)

Kjellstroem, B.; Larsson, A.E.

1967-04-01

In heat exchangers with a limited surface temperature such as reactor fuel elements, rough heat transfer surfaces may give lower pumping power than smooth. To obtain data for choice of the most advantageous roughness for the superheater elements in the Marviken reactor, measurements were made of heat transfer and pressure drop in an annular channel with a smooth or rough test rod in a smooth adiabatic shroud. 24 different roughness geometries were tested. The results were transformed to rod cluster geometry by the method of W B Hall, and correlated by the friction and heat transfer similarity laws as suggested by D F Dipprey and R H Sabersky with RMS errors of 12.5 % in the friction factor and 8.1 % in the Stanton number. The relation between the Stanton number and the friction factor could be described by a relation of the type suggested by W Nunner, with a mean error of 3.1 % and an RMS error of 11.6 %. Application of the results to fuel element calculations is discussed, and the great gains in economy which can be obtained with rough surfaces are demonstrated by two examples

Osteoblastic response to pectin nanocoating on titanium surfaces

DEFF Research Database (Denmark)

Gurzawska, Katarzyna; Svava, Rikke; Yihua, Yu

2014-01-01

with respect to surface properties and osteogenic response in osteoblastic cells. Nanocoatings on titanium surfaces were evaluated by scanning electron microscopy, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of coated RG-Is on cell adhesion, cell...

Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys

Energy Technology Data Exchange (ETDEWEB)

Rahman, Zia ur; Shabib, Ishraq [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States); Haider, Waseem, E-mail: haide1w@cmich.edu [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States)

2016-10-01

In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility. - Highlights: • Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy. • The cyclic polarization tests revealed noticeable improvement towards the positive potentials for both Tip coatings. • CpTi-Hap and Ti6Al4V-Hap both demonstrate similar corrosion rate. • High cytotoxicity was observed for Mp when compared with Tip and Hap after 21 days of immersion. • Both Tip and Hap coatings promoted the osteoblast cell adhesion and exhibited stellar morphology.

Capillary adhesion between elastic solids with randomly rough surfaces

International Nuclear Information System (INIS)

Persson, B N J

2008-01-01

I study how the contact area and the work of adhesion between two elastic solids with randomly rough surfaces depend on the relative humidity. The surfaces are assumed to be hydrophilic, and capillary bridges form at the interface between the solids. For elastically hard solids with relatively smooth surfaces, the area of real contact and therefore also the sliding friction are maximal when there is just enough liquid to fill out the interfacial space between the solids, which typically occurs for d K ∼3h rms , where d K is the height of the capillary bridge and h rms the root-mean-square roughness of the (combined) surface roughness profile. For elastically soft solids, the area of real contact is maximal for very low humidity (i.e. small d K ), where the capillary bridges are able to pull the solids into nearly complete contact. In both cases, the work of adhesion is maximal (and equal to 2γcosθ, where γ is the liquid surface tension and θ the liquid-solid contact angle) when d K >> h rms , corresponding to high relative humidity

In vitro biocompatibility of titanium after plasma surface alloying with boron

Energy Technology Data Exchange (ETDEWEB)

Kaczmarek, Mariusz, E-mail: markacz@ump.edu.pl [Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Jurczyk, Mieczysława U. [Division Mother' s and Child' s Health, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Miklaszewski, Andrzej [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland); Paszel-Jaworska, Anna; Romaniuk, Aleksandra; Lipińska, Natalia [Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, Przybyszewskiego 49, 60-355 Poznan (Poland); Żurawski, Jakub [Department of Immunobiochemistry, Chair of Biology and Environmental Sciences, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznan (Poland); Urbaniak, Paulina [Department of Cell Biology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Jurczyk, Karolina [Department of Conservative Dentistry and Periodontology, Poznan University of Medical Sciences, Bukowska 70, 60-812 Poznan (Poland)

2016-12-01

Recently, the effect of different sizes of precursor powders during surface plasma alloying modification on the properties of titanium surface was studied. In this work we show in vitro test results of the titanium (α-Ti) after plasma surface alloying with boron (B). Ti-B nanopowders with 2 and 10 wt% B were deposited onto microcrystalline Ti substrate. The in vitro cytocompatibility of these biomaterials was evaluated and compared with a conventional microcrystalline Ti. During the studies, established cell line of human gingival fibroblasts and osteoblasts were cultured in the presence of tested materials, and its survival rate and proliferation activity were examined. For this purpose, MTT assay, flow cytometric and fluorescent microscopic evaluation were made. Biocompatibility tests carried out indicate that the Ti after plasma surface alloying with B could be a possible candidate for dental implants and other medicinal applications. Plasma alloying is a promising method for improving the properties of titanium, thus increasing the field of its applications. - Highlights: • this is first article carried out on the titanium after plasma surface alloying with different contents of boron; • microcrystalline titanium modified with boron changes the physicochemical features of conventional material; • Ti modified by boron is proper in terms of effects on survival and proliferative activity of cells of dental alveoli; • precursors with different content of boron in different ways influence the intensity and stability of cell growth;.

Electrochemical construction of a bio-inspired micro/nano-textured structure with cell-sized microhole arrays on biomedical titanium to enhance bioactivity

International Nuclear Information System (INIS)

Liang, Jianhe; Song, Ran; Huang, Qiaoling; Yang, Yun; Lin, Longxiang; Zhang, Yanmei; Jiang, Pinliang; Duan, Hongping; Dong, Xiang; Lin, Changjian

2015-01-01

Highlights: • The bio-inspired structure mimicked mulit-level structures of natural bone. • Ordered cell-sized microhole arrays were employed as microscale structure. • High surface roughness and superhydrophilicity were achieved on the titanium surface. • The bio-inspired titanium surface showed superior ability of biomineralization. • Cell responses were enhanced on the bio-inspired micro/nano-texutred surface. - Abstract: Biomimetic surface design of medical implants is vitally crucial to improve cellular responses and the integration of tissue onto materials. In this study, a novel hierarchical cell-sized microhole array combined with a nano-network structure was fabricated on a medical titanium surface to mimic multi-level bone structure. A three-step procedure was developed as follows: 1) electrochemical self-organization of etching on titanium substrate to create highly ordered cell-sized microhole arrays, 2) suitable dual acid etching to increase the roughness of the microholes, and then 3) electrochemical anodization in a NaOH electrolyte to construct a nano-network porous titania layer on the above micro-roughened surface. The bio-inspired micro/nano-textured structure presented the enhanced wettability and superhydrophilicity. The ability of in vitro biomineralization and corrosion resistance of the bio-inspired micro/nano-textured structure were enhanced after annealing treatment. More importantly, the bio-inspired micro/nano-textured structure on the titanium surface possessed a favourable interfacial environment to enhance attachment and proliferation of human osteoblast-like MG63 cells. All of the results demonstrated that such a bio-inspired surface of micro/nano-textured porous TiO 2 is a most promising candidate for the next generation of titanium implants

Prediction of Ductile Fracture Surface Roughness Scaling

DEFF Research Database (Denmark)

Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth

2012-01-01

. Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting......Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low...

Evaluation of in vitro and in vivo tests for surface-modified titanium by H2SO4 and H2O2 treatment

Science.gov (United States)

Lee, Min-Ho; Park, Il-Song; Min, Kwan-Sik; Ahn, Seung-Geun; Park, Ju-Mi; Song, Kwang-Yeob; Park, Charn-Woon

2007-04-01

Titanium is widely used as an implant material for artificial teeth. Furthermore, various studies have examined surface treatment with respect to the formation of a fine passive film on the surface of commercial titanium and its alloys and to improve the bioactivity with bone. However, there is insufficient data about the biocompatibility of implant materials in the body. The purpose of this study was to examine whether surface modification affects the precipitation of apatite on titanium metal. Specimens were chemically washed for 2 min in a 1∶1∶1.5 (vol.%) mixture of 48 %HF, 60%HNO3 and distilled water. The specimens were then chemically treated with a solution containing 97%H2SO4 and 30%H2O2 at the ratio of 1∶1 (vol.%) at 40°C for 1h, and subsequently heat-treated at 400°C for 1h. All the specimens were immersed in HBSS with pH 7.4 at 36.5°C for 15d, and the surface was examined with TF-XRD, SEM, EDX and XPS. In addition, specimens of commercial pure Ti, with and without surface treatment, were implanted in the abdominal connective tissue of mice for 28 d. Conventional aluminum and stainless steel 316L were also implanted for comparison. An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a solution of H2SO4 and H2O2. The average roughness was 2.175 μm after chemical surface treatment. The amorphous titania was subsequently transformed into anatase by heat treatment at 400°C for 1h. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was 47.1μm in the chemically treated Ti, and 52.2, 168.7 and 101.9μm, respectively, in the untreated commercial pure Ti, aluminum and stainless steel 316L.

Near-field flow structures about subcritical surface roughness

Science.gov (United States)

Doolittle, Charles J.; Drews, Scott D.; Goldstein, David B.

2014-12-01

Laminar flow over a periodic array of cylindrical surface roughness elements is simulated with an immersed boundary spectral method both to validate the method for subsequent studies and to examine how persistent streamwise vortices are introduced by a low Reynolds number roughness element. Direct comparisons are made with prior studies at a roughness-based Reynolds number Rek (=U(k) k/ν) of 205 and a diameter to spanwise spacing ratio d/λ of 1/3. Downstream velocity contours match present and past experiments very well. The shear layer developed over the top of the roughness element produces the downstream velocity deficit. Upstream of the roughness element, the vortex topology is found to be consistent with juncture flow experiments, creating three cores along the recirculation line. Streamtraces stemming from these upstream cores, however, have unexpectedly little effect on the downstream flowfield as lateral divergence of the boundary layer quickly dissipates their vorticity. Long physical relaxation time of the recirculating wake behind the roughness remains a prominent issue for simulating this type of flowfield.

Influence of Wire Electrical Discharge Machining (WEDM) process parameters on surface roughness

Science.gov (United States)

Yeakub Ali, Mohammad; Banu, Asfana; Abu Bakar, Mazilah

2018-01-01

In obtaining the best quality of engineering components, the quality of machined parts surface plays an important role. It improves the fatigue strength, wear resistance, and corrosion of workpiece. This paper investigates the effects of wire electrical discharge machining (WEDM) process parameters on surface roughness of stainless steel using distilled water as dielectric fluid and brass wire as tool electrode. The parameters selected are voltage open, wire speed, wire tension, voltage gap, and off time. Empirical model was developed for the estimation of surface roughness. The analysis revealed that off time has a major influence on surface roughness. The optimum machining parameters for minimum surface roughness were found to be at a 10 V open voltage, 2.84 μs off time, 12 m/min wire speed, 6.3 N wire tension, and 54.91 V voltage gap.

Reduced adhesion of macrophages on anodized titanium with select nanotube surface features

Directory of Open Access Journals (Sweden)

Balasubramanian K

2011-08-01

Full Text Available Amancherla Rajyalakshmi1, Batur Ercan2,3, K Balasubramanian1, Thomas J Webster2,31Non-Ferrous Materials Technology Development Centre, Hyderabad, India; 2School of Engineering, 3Department of Orthopedics, Brown University, Providence, RI, USAAbstract: One of the important prerequisites for a successful orthopedic implant apart from being osteoconductive is the elicitation of a favorable immune response that does not lead to the rejection of the implant by the host tissue. Anodization is one of the simplest surface modification processes used to create nanotextured and nanotubular features on metal oxides which has been shown to improve bone formation. Anodization of titanium (Ti leads to the formation of TiO2 nanotubes on the surface, and the presence of these nanotubes mimics the natural nanoscale features of bone, which in turn contributes to improved bone cell attachment, migration, and proliferation. However, inflammatory cell responses on anodized Ti remains to be tested. It is hypothesized that surface roughness and surface feature size on anodized Ti can be carefully manipulated to control immune cell (specifically, macrophages responses. Here, when Ti samples were anodized at 10 V in the presence of 1% hydrofluoric acid (HF for 1 minute, nanotextured (nonnanotube surfaces were created. When anodization of Ti samples was carried out with 1% HF for 10 minutes at 15 V, nanotubes with 40–50 nm diameters were formed, whereas at 20 V with 1% HF for 10 minutes, nanotubes with 60–70 nm diameters were formed. In this study, a reduced density of macrophages was observed after 24 hours of culture on nanotextured and nanotubular Ti samples which were anodized at 10, 15, and 20 V, compared with conventional unmodified Ti samples. This in vitro study thus demonstrated a reduced density of macrophages on anodized Ti, thereby providing further evidence of the greater efficacy of anodized Ti for orthopedic applications.Keywords: anodization, titanium

Surface Modification of Porous Titanium Granules for Improving Bioactivity.

Science.gov (United States)

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.

Elastic wave generated by granular impact on rough and erodible surfaces

Science.gov (United States)

Bachelet, Vincent; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud; Farin, Maxime

2018-01-01

The elastic waves generated by impactors hitting rough and erodible surfaces are studied. For this purpose, beads of variable materials, diameters, and velocities are dropped on (i) a smooth PMMA plate, (ii) stuck glass beads on the PMMA plate to create roughness, and (iii) the rough plate covered with layers of free particles to investigate erodible beds. The Hertz model validity to describe impacts on a smooth surface is confirmed. For rough and erodible surfaces, an empirical scaling law that relates the elastic energy to the radius Rb and normal velocity Vz of the impactor is deduced from experimental data. In addition, the radiated elastic energy is found to decrease exponentially with respect to the bed thickness. Lastly, we show that the variability of the elastic energy among shocks increases from some percents to 70% between smooth and erodible surfaces. This work is a first step to better quantify seismic emissions of rock impacts in natural environment, in particular on unconsolidated soils.

Non-Contact Surface Roughness Measurement by Implementation of a Spatial Light Modulator

Directory of Open Access Journals (Sweden)

Laura Aulbach

2017-03-01

Full Text Available The surface structure, especially the roughness, has a significant influence on numerous parameters, such as friction and wear, and therefore estimates the quality of technical systems. In the last decades, a broad variety of surface roughness measurement methods were developed. A destructive measurement procedure or the lack of feasibility of online monitoring are the crucial drawbacks of most of these methods. This article proposes a new non-contact method for measuring the surface roughness that is straightforward to implement and easy to extend to online monitoring processes. The key element is a liquid-crystal-based spatial light modulator, integrated in an interferometric setup. By varying the imprinted phase of the modulator, a correlation between the imprinted phase and the fringe visibility of an interferogram is measured, and the surface roughness can be derived. This paper presents the theoretical approach of the method and first simulation and experimental results for a set of surface roughnesses. The experimental results are compared with values obtained by an atomic force microscope and a stylus profiler.

Spatially-varying surface roughness and ground-level air quality in an operational dispersion model

International Nuclear Information System (INIS)

Barnes, M.J.; Brade, T.K.; MacKenzie, A.R.; Whyatt, J.D.; Carruthers, D.J.; Stocker, J.; Cai, X.; Hewitt, C.N.

2014-01-01

Urban form controls the overall aerodynamic roughness of a city, and hence plays a significant role in how air flow interacts with the urban landscape. This paper reports improved model performance resulting from the introduction of variable surface roughness in the operational air-quality model ADMS-Urban (v3.1). We then assess to what extent pollutant concentrations can be reduced solely through local reductions in roughness. The model results suggest that reducing surface roughness in a city centre can increase ground-level pollutant concentrations, both locally in the area of reduced roughness and downwind of that area. The unexpected simulation of increased ground-level pollutant concentrations implies that this type of modelling should be used with caution for urban planning and design studies looking at ventilation of pollution. We expect the results from this study to be relevant for all atmospheric dispersion models with urban-surface parameterisations based on roughness. -- Highlights: • Spatially variable roughness improved performance of an operational model. • Scenario modelling explored effect of reduced roughness on air pollution. • Reducing surface roughness can increase modelled ground-level pollution. • Damped vertical mixing outweighs increased horizontal advection in model study. • Result should hold for any model with a land-surface coupling based on roughness. -- Spatially varying roughness improves model simulations of urban air pollutant dispersion. Reducing roughness does not always decrease ground-level pollution concentrations

The effects of surface roughness on low haze ultrathin nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Kanniah, Vinod [Chemical and Materials Engineering, 177 F. Paul Anderson Tower, University of Kentucky, Lexington, KY 40506 (United States); Tru Vue, Inc. 9400 West, 55th St, McCook, IL 60525 (United States); Grulke, Eric A., E-mail: eric.grulke@uky.edu [Chemical and Materials Engineering, 177 F. Paul Anderson Tower, University of Kentucky, Lexington, KY 40506 (United States); Druffel, Thad [Vision Dynamics LLC, 1950 Production Court, Louisville, KY 40299 (United States); Conn Center for Renewable Energy Research, University of Louisville, Ernst Hall Room 102A, Louisville, KY 40292 (United States)

2013-07-31

Control of surface roughness in optical applications can have a large impact on haze. This work compares surface roughness and haze for self-assembled experimental surface structures as well as simulated surface structures for ultrathin nanocomposite films. Ultrathin nanocomposite films were synthesized from an acrylate monomer as the continuous phase with monodisperse or bidisperse mixtures of silica nanoparticles as the dispersed phase. An in-house spin coating deposition technique was used to make thin nanocomposite films on hydrophilic (glass) and hydrophobic (polycarbonate) substrates. Manipulating the size ratios of the silica nanoparticle mixtures generated multimodal height distributions, varied the average surface roughness (σ) and changed lateral height–height correlations (a). For the simulated surfaces, roughness was estimated from their morphologies, and haze was calculated using simplified Rayleigh scattering theory. Experimental data for haze and morphologies of nanocomposite films corresponded well to these properties for simulated tipped pyramid surfaces. A correlation based on simple Rayleigh scattering theory described our experimental data well, but the exponent on the parameter, σ/λ (λ is the wavelength of incident light), does not have the expected value of 2. A scalar scattering model and a prior Monte Carlo simulation estimated haze values similar to those of our experimental samples. - Highlights: • Bidisperse nanoparticle mixtures created structured surfaces on thin films. • Monodisperse discrete phases created unimodal structure distributions. • Bidisperse discrete phases created multimodal structure distributions. • Multimodal structures had maximum heights ≤ 1.5 D{sub large} over our variable range. • Simplified Rayleigh scattering theory linked roughness to haze and contact angle.

The role of the roughness spectral breadth in elastic contact of rough surfaces

Science.gov (United States)

Yastrebov, Vladislav A.; Anciaux, Guillaume; Molinari, Jean-François

2017-10-01

We study frictionless and non-adhesive contact between elastic half-spaces with self-affine surfaces. Using a recently suggested corrective technique, we ensure an unprecedented accuracy in computation of the true contact area evolution under increasing pressure. This accuracy enables us to draw conclusions on the role of the surface's spectrum breadth (Nayak parameter) in the contact area evolution. We show that for a given normalized pressure, the contact area decreases logarithmically with the Nayak parameter. By linking the Nayak parameter with the Hurst exponent (or fractal dimension), we show the effect of the latter on the true contact area. This effect, undetectable for surfaces with poor spectral content, is quite strong for surfaces with rich spectra. Numerical results are compared with analytical models and other available numerical results. A phenomenological equation for the contact area growth is suggested with coefficients depending on the Nayak parameter. Using this equation, the pressure-dependent friction coefficient is deduced based on the adhesive theory of friction. Some observations on Persson's model of rough contact, whose prediction does not depend on Nayak parameter, are reported. Overall, the paper provides a unifying picture of rough elastic contact and clarifies discrepancies between preceding results.

Surface roughness of glass ionomer cements indicated for uncooperative patients according to surface protection treatment.

Science.gov (United States)

Pacifici, Edoardo; Bossù, Maurizio; Giovannetti, Agostino; La Torre, Giuseppe; Guerra, Fabrizio; Polimeni, Antonella

2013-01-01

Even today, use of Glass Ionomer Cements (GIC) as restorative material is indicated for uncooperative patients. The study aimed at estimating the surface roughness of different GICs using or not their proprietary surface coatings and at observing the interfaces between cement and coating through SEM. Forty specimens have been obtained and divided into 4 groups: Fuji IX (IX), Fuji IX/G-Coat Plus (IXC), Vitremer (V), Vitremer/Finishing Gloss (VFG). Samples were obtained using silicone moulds to simulate class I restorations. All specimens were processed for profilometric evaluation. The statistical differences of surface roughness between groups were assessed using One-Way Analysis of Variance (One-Way ANOVA) (p<0.05). The Two-Way Analysis of Variance (Two-Way ANOVA) was used to evaluate the influence of two factors: restoration material and presence of coating. Coated restoration specimens (IXC and VFG) were sectioned perpendicular to the restoration surface and processed for SEM evaluation. No statistical differences in roughness could be noticed between groups or factors. Following microscopic observation, interfaces between restoration material and coating were better for group IXC than for group VFG. When specimens are obtained simulating normal clinical procedures, the presence of surface protection does not significantly improve the surface roughness of GICs.

Functionalized PDMS with versatile and scalable surface roughness gradients for cell culture

KAUST Repository

Zhou, Bingpu

2015-07-21

This manuscript describes a simple and versatile approach to engineering surface roughness gradients via combination of microfluidics and photo-polymerization. Through UV-mediated polymerization, N-isopropylacrylamide with concentration gradients are successfully grafted onto PDMS surface, leading to diverse roughness degrees on the obtained PDMS substrate. Furthermore, the extent of surface roughness can be controllably regulated via tuning the flow rate ratio between the monomer solution and deionized water. Average roughness ranging from 8.050 nm to 151.68 nm has well been achieved in this work. Such PDMS samples are also demonstrated to be capable of working as supporting substrates for controlling cell adhesion or detachment. Due to the different degrees of surface roughness on a single substrate, our method provides an effective approach for designing advanced surafecs for cell culture. Finally, the thermosensitive property of N-isopropylacrylamide makes our sample furnish as another means for controlling the cell detachment from the substrates with correspondence to the surrounding temperature.

Functionalized PDMS with versatile and scalable surface roughness gradients for cell culture

KAUST Repository

Zhou, Bingpu; Gao, Xinghua; Wang, Cong; Ye, Ziran; Gao, Yibo; Xie, Jiao; Wu, Xiaoxiao; Wen, Weijia

2015-01-01

This manuscript describes a simple and versatile approach to engineering surface roughness gradients via combination of microfluidics and photo-polymerization. Through UV-mediated polymerization, N-isopropylacrylamide with concentration gradients are successfully grafted onto PDMS surface, leading to diverse roughness degrees on the obtained PDMS substrate. Furthermore, the extent of surface roughness can be controllably regulated via tuning the flow rate ratio between the monomer solution and deionized water. Average roughness ranging from 8.050 nm to 151.68 nm has well been achieved in this work. Such PDMS samples are also demonstrated to be capable of working as supporting substrates for controlling cell adhesion or detachment. Due to the different degrees of surface roughness on a single substrate, our method provides an effective approach for designing advanced surafecs for cell culture. Finally, the thermosensitive property of N-isopropylacrylamide makes our sample furnish as another means for controlling the cell detachment from the substrates with correspondence to the surrounding temperature.

The effect of machining parameters on surface roughness during turning of stainless steel

International Nuclear Information System (INIS)

El-Belazi, Khalid M.

1991-03-01

Surface roughness is a direct consequence of the cutting tool action, its assessment and control represent an effective way by which the machining process can be studied. The control of surface roughness has become increasingly important during the last thirty years, because the quality of surface is extremely important for machined components that have been designed to stand to static and cyclic loads. This work has two major goals. The first is to develop a new theoretical model based on the assumption that the shape of the cutting tool nose is elliptical to evaluate the surface roughness parameters. The second is to investigate the effect of cutting speed, feed rate, overhang length, tool nose radius (circular sharp), and depth of cut on surface roughness of turned surfaces of austenitic stainless steel grade 12X18H10T. It was found from the theoretical part that the surface roughness values obtained from the elliptical model are much better than those obtained from the other models. It was found from the experimental work that the surface roughness values increase by increasing cutting speed, feed rate, depth of cut, and overhang length, and fluctuates when using cutting tools with various nose radii, during turning of the above mentioned steel by using a brazed carbide cutting tool. (author)

Analysis of multi lobe journal bearings with surface roughness using finite difference method

Science.gov (United States)

PhaniRaja Kumar, K.; Bhaskar, SUdaya; Manzoor Hussain, M.

2018-04-01

Multi lobe journal bearings are used for high operating speeds and high loads in machines. In this paper symmetrical multi lobe journal bearings are analyzed to find out the effect of surface roughnessduring non linear loading. Using the fourth order RungeKutta method, time transient analysis was performed to calculate and plot the journal centre trajectories. Flow factor method is used to evaluate the roughness and the finite difference method (FDM) is used to predict the pressure distribution over the bearing surface. The Transient analysis is done on the multi lobe journal bearings for threedifferent surface roughness orientations. Longitudinal surface roughness is more effective when compared with isotopic and traverse surface roughness.

Improved the Surface Roughness of Silicon Nanophotonic Devices by Thermal Oxidation Method

Energy Technology Data Exchange (ETDEWEB)

Shi Zujun; Shao Shiqian; Wang Yi, E-mail: ywangwnlo@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, No. 1037, Luoyu Street, Wuhan 430074 (China)

2011-02-01

The transmission loss of the silicon-on-insulator (SOI) waveguide and the coupling loss of the SOI grating are determined to a large extent by the surface roughness. In order to obtain smaller loss, thermal oxidation is a good choice to reduce the surface roughness of the SOI waveguide and grating. Before the thermal oxidation, the root mean square of the surface roughness is over 11 nm. After the thermal oxidation, the SEM figure shows that the bottom of the grating is as smooth as quartz surface, while the AFM shows that the root mean square of the surface is less than 5 nm.

Effect of different surface treatments on roughness of IPS Empress 2 ceramic.

Science.gov (United States)

Kara, Haluk Baris; Dilber, Erhan; Koc, Ozlem; Ozturk, A Nilgun; Bulbul, Mehmet

2012-03-01

The aim of this study was to evaluate the influence of different surface treatments (air abrasion, acid etching, laser irradiation) on the surface roughness of a lithium-disilicate-based core ceramic. A total of 40 discs of lithium disilicate-based core ceramic (IPS Empress 2; Ivoclar Vivadent, Schaan, Liechtenstein) were prepared (10 mm in diameter and 1 mm in thickness) according to the manufacturer's instructions. Specimens were divided into four groups (n = 10), and the following treatments were applied: air abrasion with alumina particles (50 μm), acid etching with 5% hydrofluoric acid, Nd:YAG laser irradiation (1 mm distance, 100 mJ, 20 Hz, 2 W) and Er:YAG laser irradiation (1 mm distance, 500 mJ, 20 Hz, 10 W). Following determination of surface roughness (R(a)) by profilometry, specimens were examined with atomic force microscopy. The data were analysed by one-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). One-way ANOVA indicated that surface roughness following air abrasion was significantly different from the surface roughness following laser irradiation and acid etching (P 0.05). Air abrasion increased surface roughness of lithium disilicate-based core ceramic surfaces more effectively than acid-etching and laser irradiation.

Effect of Al_2O_3 nanolubrication with Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear under MQL during turning of Ti-6AL-4T

International Nuclear Information System (INIS)

Ali, M A M; Khalil, A N M; Azmi, A I

2016-01-01

The application of coolant reduces the friction and heat generation, which affect the surface finish and tool life, during machining. Recently, nanolubricant opens a new ways of coolant strategy in machining operation. It is well known that suspended nanoparticles without surfactant in base oil tend to agglomerate after a period of time. This paper presents the effects of AEO_3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear during turning of titanium alloy, Ti-6AL-4T. The comparison of different coolant strategies, dry cutting, flooding, minimum quantity lubricant (MQL), nanolubricant with and without surfactant are also presented. The results showed that Al_2O_3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) under MQL exhibits low surface roughness and tool wear rate compared to others. This proved that the addition of surfactant not only improved nanolubricant stability but also machining performance. (paper)

Enhancement of vortex induced forces and motion through surface roughness control

Science.gov (United States)

Bernitsas, Michael M [Saline, MI; Raghavan, Kamaldev [Houston, TX

2011-11-01

Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium.

Science.gov (United States)

Iwasa, Fuminori; Tsukimura, Naoki; Sugita, Yoshihiko; Kanuru, Rajita Kodali; Kubo, Katsutoshi; Hasnain, Hafiz; Att, Wael; Ogawa, Takahiro

2011-01-01

Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO(2) nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow-derived osteoblasts were cultured on fresh disks (immediately after UV treatment), 3-day-old disks (disks stored for 3 days after UV treatment), and 7-day- old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%-50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano- hybrid surfaces became hydrorepellent, while the micropit surfaces remained hydrophilic. The sustained bioactivity levels of the micro-nano-hybrid surfaces were nullified by treating these surfaces with Cl(-)anions. A thin TiO(2) coating on the micropit surface without the formation of nanonodules did not result in the prevention or alleviation of the time-dependent decrease in biological activity. In conclusion, the micro-nano-hybrid titanium surfaces may slow the rate of time-dependent degradation of titanium

Optimization of surface roughness in CNC end milling using ...

African Journals Online (AJOL)

International Journal of Engineering, Science and Technology ... In this study, minimization of surface roughness has been investigated by integrating design of experiment method, Response surface methodology (RSM) and genetic algorithm ...

Effects of polishing on surface roughness, gloss, and color of resin composites.

Science.gov (United States)

Hosoya, Yumiko; Shiraishi, Takanobu; Odatsu, Tetsuro; Nagafuji, Junichi; Kotaku, Mayumi; Miyazaki, Masashi; Powers, John M

2011-09-01

This study evaluated the effects of polishing on surface roughness, gloss, and color of regular, opaque, and enamel shades for each of three resin composites. Two-mm-thick resin disks made with Estelite Σ Quick, Clearfil Majesty, and Beautifil II were final polished with 180-, 1000-, and 3000-grit silicon carbide paper. Surface roughness, gloss, and color were measured one week after curing. Estelite Σ Quick had significantly lower roughness values and significantly higher gloss values as compared with Clearfil Majesty and Beautifil II. The effects of surface roughness and gloss on color (L*a*b*) differed among resin composites and by shade. Correlation coefficients between surface roughness and L*a*b* color factors were generally high for Clearfil Majesty, partially high (i.e., between roughness and L*) for Beautifil II, and low for Estelite Σ Quick. Correlation coefficients between gloss and L*a*b* color parameters were generally high for Beautifil II and low for Estelite Σ Quick and Clearfil Majesty. However, for all resin composites, the values of the color differences between 3000-grit and 180-grit polishing groups for all shades were imperceptible by the naked eye.

Effect of simulated mastication on the surface roughness of three ceramic systems.

Science.gov (United States)

Amer, Rafat; Kürklü, Duygu; Johnston, William

2015-08-01

Zirconia complete coverage crowns are being widely used as restorations because of their high strength and improved esthetics. Data are sparse about the change in surface roughness of this ceramic material after repeated mastication cycles of opposing enamel. The purpose of this study was to investigate changes in the surface roughness after being subjected to 3-body wear-opposing human enamel of 3 types of ceramics: dense sintered yttrium-stabilized zirconia (Z); lithium disilicate (L); and a conventional low-fusing feldspathic porcelain (P) treated to impart a rough, smooth, or glazed surface. Twenty-four specimens of each of the Z and L ceramic were sectioned from computer-aided design and computer-aided manufacturing blocks into rectangular plates (15×12×2 mm). Twenty-four specimens of the feldspathic porcelain were formed into disks (12-mm diameter) from powders compressed in a silicone mold. All specimens (n=72) were prepared according to the manufacturers' recommendations. Specimens of each ceramic group were placed into 1 of 3 groups: group R, rough surface finish; group S, smooth surface finish; and group G, glazed surface finish. A total of 72 specimens (9 groups with 8 specimens each) was placed in a 3-body wear simulator, with standardized enamel specimens (n=72) acting as the substrate. The changes in surface roughness of the ceramic specimens were evaluated after 50,000 cycles. Data were analyzed by a repeated measures 3-way ANOVA mixed procedure with the Satterthwaite method for degrees of freedom and maximum likelihood estimation of the covariance parameters (α=.05). Data showed that the PS group exhibited the largest change in surface roughness, becoming significantly rougher (P<.004). The LR group became significantly smoother (P=.012). The surfaces of monolithic zirconia ceramic and lithium disilicate did not become as rough as the surface of conventional feldspathic porcelain after enamel wear. Copyright © 2015 Editorial Council for the

On the computation of the turbulent flow near rough surface

Science.gov (United States)

Matveev, S. K.; Jaychibekov, N. Zh.; Shalabayeva, B. S.

2018-05-01

One of the problems in constructing mathematical models of turbulence is a description of the flows near a rough surface. An experimental study of such flows is also difficult because of the impossibility of measuring "inside" the roughness. The theoretical calculation is difficult because of the lack of equations describing the flow in this zone. In this paper, a new turbulence model based on the differential equation of turbulent viscosity balance was used to describe a turbulent flow near a rough surface. The difference between the new turbulence model and the previously known consists in the choice of constants and functions that determine the generation, dissipation and diffusion of viscosity.

Modified Titanium Surface-Mediated Effects on Human Bone Marrow Stromal Cell Response

Directory of Open Access Journals (Sweden)

Amol Chaudhari

2013-11-01

Full Text Available Surface modification of titanium implants is used to enhance osseointegration. The study objective was to evaluate five modified titanium surfaces in terms of cytocompatibility and pro-osteogenic/pro-angiogenic properties for human mesenchymal stromal cells: amorphous microporous silica (AMS, bone morphogenetic protein-2 immobilized on AMS (AMS + BMP, bio-active glass (BAG and two titanium coatings with different porosity (T1; T2. Four surfaces served as controls: uncoated Ti (Ti, Ti functionalized with BMP-2 (Ti + BMP, Ti surface with a thickened titanium oxide layer (TiO2 and a tissue culture polystyrene surface (TCPS. The proliferation of eGFP-fLuc (enhanced green fluorescence protein-firefly luciferase transfected cells was tracked non-invasively by fluorescence microscopy and bio-luminescence imaging. The implant surface-mediated effects on cell differentiation potential was tracked by determination of osteogenic and angiogenic parameters [alkaline phosphatase (ALP; osteocalcin (OC; osteoprotegerin (OPG; vascular endothelial growth factor-A (VEGF-A]. Unrestrained cell proliferation was observed on (unfunctionalized Ti and AMS surfaces, whereas BAG and porous titanium coatings T1 and T2 did not support cell proliferation. An important pro-osteogenic and pro-angiogenic potential of the AMS + BMP surface was observed. In contrast, coating the Ti surface with BMP did not affect the osteogenic differentiation of the progenitor cells. A significantly slower BMP-2 release from AMS compared to Ti supports these findings. In the unfunctionalized state, Ti was found to be superior to AMS in terms of OPG and VEGF-A production. AMS is suggested to be a promising implant coating material for bioactive agents delivery.

Characterizing the effects of regolith surface roughness on photoemission from surfaces in space

Science.gov (United States)

Dove, A.; Horanyi, M.; Wang, X.

2017-12-01

Surfaces of airless bodies and spacecraft in space are exposed to a variety of charging environments. A balance of currents due to plasma bombardment, photoemission, electron and ion emission and collection, and secondary electron emission determines the surface's charge. Photoelectron emission is the dominant charging process on sunlit surfaces in the inner solar system due to the intense solar UV radiation. This can result in a net positive surface potential, with a cloud of photoelectrons immediately above the surface, called the photoelectron sheath. Conversely, the unlit side of the body will charge negatively due the collection of the fast-moving solar wind electrons. The interaction of charged dust grains with these positively and negatively charged surfaces, and within the photoelectron and plasma sheaths may explain the occurrence of dust lofting, levitation and transport above the lunar surface. The surface potential of exposed objects is also dependent on the material properties of their surfaces. Composition and particle size primarily affect the quantum efficiency of photoelectron generation; however, surface roughness can also control the charging process. In order to characterize these effects, we have conducted laboratory experiments to examine the role of surface roughness in generating photoelectrons in dedicated laboratory experiments using solid and dusty surfaces of the same composition (CeO2), and initial comparisons with JSC-1 lunar simulant. Using Langmuir probe measurements, we explore the measured potentials above insulating surfaces exposed to UV and an electric field, and we show that the photoemission current from a dusty surface is largely reduced due to its higher surface roughness, which causes a significant fraction of the emitted photoelectrons to be re-absorbed within the surface. We will discuss these results in context of similar situations on planetary surfaces.

New surface modification method of bio-titanium alloy by EB polishing

International Nuclear Information System (INIS)

Okada, Akira; Uno, Yoshiyuki; Iio, Atsuo; Fujiwara, Kunihiko; Doi, Kenji

2008-01-01

A new surface modification for bio-titanium alloy products by electron beam (EB) polishing is proposed. In this EB polishing method, high energy density EB can be irradiated without concentrating the beam. Therefore, large-area EB with a maximum diameter of 60 mm can be used for instantaneously melting or evaporating metal surface. Experimental results made it clear that surface characteristics, such as repellency, corrosion resistance and coefficient of friction could be improved simultaneously with the surface smoothing in a few minutes under a proper condition. Therefore, EB polishing method has a possibility of high efficient surface smoothing and surface modification process for bio-titanium alloy. (author)

The surface roughness effect on the performance of supersonic ejectors

Science.gov (United States)

Brezgin, D. V.; Aronson, K. E.; Mazzelli, F.; Milazzo, A.

2017-07-01

The paper presents the numerical simulation results of the surface roughness influence on gas-dynamic processes inside flow parts of a supersonic ejector. These simulations are performed using two commercial CFD solvers (Star- CCM+ and Fluent). The results are compared to each other and verified by a full-scale experiment in terms of global flow parameters (the entrainment ratio: the ratio between secondary to primary mass flow rate - ER hereafter) and local flow parameters distribution (the static pressure distribution along the mixing chamber and diffuser walls). A detailed comparative study of the employed methods and approaches in both CFD packages is carried out in order to estimate the roughness effect on the logarithmic law velocity distribution inside the boundary layer. Influence of the surface roughness is compared with the influence of the backpressure (static pressure at the ejector outlet). It has been found out that increasing either the ejector backpressure or the surface roughness height, the shock position displaces upstream. Moreover, the numerical simulation results of an ejector with rough walls in the both CFD solvers are well quantitatively agreed with each other in terms of the mean ER and well qualitatively agree in terms of the local flow parameters distribution. It is found out that in the case of exceeding the "critical roughness height" for the given boundary conditions and ejector's geometry, the ejector switches to the "off-design" mode and its performance decreases considerably.

Fabricating Superhydrophobic and Superoleophobic Surfaces with Multiscale Roughness Using Airbrush and Electrospray

Science.gov (United States)

AL-Milaji, Karam N.

Examples of superhydrophobic surfaces found in nature such as self-cleaning property of lotus leaf and walking on water ability of water strider have led to an extensive investigation in this area over the past few decades. When a water droplet rests on a textured surface, it may either form a liquid-solid-vapor composite interface by which the liquid droplet partially sits on air pockets or it may wet the surface in which the water replaces the trapped air depending on the surface roughness and the surface chemistry. Super water repellent surfaces have numerous applications in our daily life such as drag reduction, anti-icing, anti-fogging, energy conservation, noise reduction, and self-cleaning. In fact, the same concept could be applied in designing and producing surfaces that repel organic contaminations (e.g. low surface tension liquids). However, superoleophobic surfaces are more challenging to fabricate than superhydrophobic surfaces since the combination of multiscale roughness with re-entrant or overhang structure and surface chemistry must be provided. In this study, simple, cost-effective and potentially scalable techniques, i.e., airbrush and electrospray, were employed for the sake of making superhydrophobic and superoleophobic coatings with random and patterned multiscale surface roughness. Different types of silicon dioxide were utilized in this work to in order to study and to characterize the effect of surface morphology and surface roughness on surface wettability. The experimental findings indicated that super liquid repellent surfaces with high apparent contact angles and extremely low sliding angles were successfully fabricated by combining re-entrant structure, multiscale surface roughness, and low surface energy obtained from chemically treating the fabricated surfaces. In addition to that, the experimental observations regarding producing textured surfaces in mask-assisted electrospray were further validated by simulating the actual working