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Sample records for surface area zirconia

  1. Surface-Casting Synthesis of Mesoporous Zirconia with a CMK-5-Like Structure and High Surface Area.

    PubMed

    Gu, Dong; Schmidt, Wolfgang; Pichler, Christian M; Bongard, Hans-Josef; Spliethoff, Bernd; Asahina, Shunsuke; Cao, Zhengwen; Terasaki, Osamu; Schüth, Ferdi

    2017-09-04

    About 15 years ago, the Ryoo group described the synthesis of CMK-5, a material consisting of a hexagonal arrangement of carbon nanotubes. Extension of the surface casting synthesis to oxide compositions, however, was not possible so far, in spite of many attempts. Here it is demonstrated, that crystalline mesoporous hollow zirconia materials with very high surface areas up to 400 m(2)  g(-1) , and in selected cases in the form of CMK-5-like, are indeed accessible via such a surface casting process. The key for the successful synthesis is an increased interaction between the silica hard template surface and the zirconia precursor species by using silanol group-rich mesoporous silica as a hard template. The surface areas of the obtained zirconias exceed those of conventionally hard-templated ones by a factor of two to three. The surface casting process seems to be applicable also to other oxide materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ruthenium catalysts supported on high-surface-area zirconia for the catalytic wet oxidation of N,N-dimethyl formamide.

    PubMed

    Sun, Guanglu; Xu, Aihua; He, Yu; Yang, Min; Du, Hongzhang; Sun, Chenglin

    2008-08-15

    Three weight percent ruthenium catalysts were prepared by incipient-wet impregnation of two different zirconium oxides, and characterized by BET, XRD and TPR. Their activity was evaluated in the catalytic wet oxidation (CWO) of N,N-dimethyl formamide (DMF) in an autoclave reactor. Due to a better dispersion, Ru catalyst supported on a high-surface-area zirconia (Ru/ZrO(2)-A) possessed higher catalytic properties. Due to over-oxidation of Ru particles, the catalytic activity of the both catalysts decreased during successive tests. The effect of oxygen partial pressure and reaction temperature on the DMF reactivity in the CWO on Ru/ZrO(2)-A was also investigated. 98.6% of DMF conversion was obtained through hydrothermal decomposition within 300 min at conditions of 200 degrees C and 2.0 MPa of nitrogen pressure. At 240 degrees C and 2.0 MPa of oxygen pressure 98.3% of DMF conversion was obtained within 150 min.

  3. Surface properties of titanium and zirconia dental implant materials and their effect on bacterial adhesion.

    PubMed

    Al-Radha, Afya Sahib Diab; Dymock, David; Younes, Charles; O'Sullivan, Dominic

    2012-02-01

    Zirconia ceramic material has been widely used in implant dentistry. In this in vitro study the physiochemical properties of titanium and zirconia materials were investigated and the affinity of different bacteria to different materials was compared. Disc samples with different surface states were used: polished partially stabilized zirconia (PZ), titanium blasted with zirconia (TBZ), titanium blasted with zirconia then acid etched (TBZA), and polished titanium (PT) as a control. Surface topography was examined using scanning electron microscopy and profilometry. Contact angle, surface free energy (SFE), surface microhardness and chemical composition were determined. Disc samples were separately incubated with Streptococcus mitis and Prevotella nigrescens, either with or without pre-coating with human saliva, for 6h and the surface area covered by bacteria was calculated from fluorescence microscope images. PZ and TBZ exhibited lower surface free energy and lesser surface wettability than PT. Also, PZ and TBZ surfaces showed lower percentage of bacterial adhesion compared with control PT surface. The zirconia material and titanium blasted with zirconia surface (TBZ surface) showed superior effect to titanium material in reducing the adhesion of the experimented bacteria especially after coating with saliva pellicle. Modifying titanium with zirconia lead to have the same surface properties of pure zirconia material in reducing bacterial adhesion. SFE appears to be the most important factors that determine initial bacterial adhesion to smooth surface. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Effects of cementation surface modifications on fracture resistance of zirconia.

    PubMed

    Srikanth, Ramanathan; Kosmac, Tomaz; Della Bona, Alvaro; Yin, Ling; Zhang, Yu

    2015-04-01

    To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia. Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending. Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength. While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Effects of cementation surface modifications on fracture resistance of zirconia

    PubMed Central

    Srikanth, Ramanathan; Kosmac, Tomaz; Bona, Alvaro Della; Yin, Ling; Zhang, Yu

    2015-01-01

    Objectives To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia. Methods Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 mm or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2 mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending. Results Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength. Significance While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia. PMID:25687628

  6. Low Energy Surface Activation of Zirconia Based Restorations.

    PubMed

    Aboushelib, Moustafa N

    2016-03-01

    To evaluate the influence of low energy surface activation technique on the biaxial flexure strength of zirconia frameworks. Zirconia discs were prepared by cutting CAD/CAM zirconia blocks. Sintered discs were airborne particle abraded using one of the following particles: 30 μm alumina particles, 50 μm alumina particles, or modified round edges 30 μm alumina particles at low pressure. Scanning electron microscopy, x-ray diffraction analysis, surface roughness, and biaxial flexure strength tests were performed (n = 20). Fractured specimens were fractographically analyzed (α = 0.05). Low energy surface activation resulted in 7% monoclinic crystallographic transformation, increasing surface roughness from 0.05 to 0.3 μm and in significant increase in biaxial flexure strength (1718 MPa) compared 30 μm (1064 MPa), 50 μm (1210 MPa), and as-sintered specimens (1150 MPa). Low energy surface activation of zirconia specimens improved the biaxial flexure strength of zirconia frameworks without creation of surface damage. Clinical implications: by controlling particle size and shape of alumina, the flexure strength of zirconia restorations could be increased usinglow pressure particle abrasion.

  7. Novel Zirconia Surface Treatments for Enhanced Osseointegration: Laboratory Characterization

    PubMed Central

    Ewais, Ola H.; Al Abbassy, Fayza; Ghoneim, Mona M.; Aboushelib, Moustafa N.

    2014-01-01

    Purpose. The aim of this study was to evaluate three novel surface treatments intended to improve osseointegration of zirconia implants: selective infiltration etching treatment (SIE), fusion sputtering (FS), and low pressure particle abrasion (LPPA). The effects of surface treatments on roughness, topography, hardness, and porosity of implants were also assessed. Materials and Methods. 45 zirconia discs (19 mm in diameter × 3 mm in thickness) received 3 different surface treatments: selective infiltration etching, low pressure particle abrasion with 30 µm alumina, and fusion sputtering while nontreated surface served as control. Surface roughness was evaluated quantitatively using profilometery, porosity was evaluated using mercury prosimetry, and Vickers microhardness was used to assess surface hardness. Surface topography was analyzed using scanning and atomic force microscopy (α = 0.05). Results. There were significant differences between all groups regarding surface roughness (F = 1678, P < 0.001), porosity (F = 3278, P < 0.001), and hardness (F = 1106.158, P < 0.001). Scanning and atomic force microscopy revealed a nanoporous surface characteristic of SIE, and FS resulted in the creation of surface microbeads, while LPPA resulted in limited abrasion of the surface. Conclusion. Within the limitations of the study, changes in surface characteristics and topography of zirconia implants have been observed after different surface treatment approaches. Thus possibilities for enhanced osseointegration could be additionally offered. PMID:25349610

  8. An in vitro evaluation of the zirconia surface treatment by mesoporous zirconia coating on its bonding to resin cement.

    PubMed

    Zhang, Yanli; Sun, Ting; Liu, Ruoyu; Feng, Xiaoli; Chen, Aijie; Shao, Longquan

    2014-01-01

    The effect of zirconia surface treatment by mesoporous zirconia coating on the microtensile bond strength (MTBS) between zirconia and resin cement was investigated in this work. 160 zirconia specimens were prepared and divided into four groups according to surface treatments: (1) airborne-particle-abrasion treatment (APA); (2) glass infiltration and hydrofluoric acid treatment (GI+HF); (3) mesoporous zirconia coating (MZ); and (4) no treatment (C). The as-prepared zirconia specimens were bonded using Panavia F2.0 and RelyX Unicem. The MTBS values were tested using a universal testing machine, and data were analyzed using ANOVA and SNK methods (a=0.05). The MTBS values obtained after GI+HF and MZ treatments were significantly higher than those obtained after APA and C treatments (P<0.05), especially for samples cemented with Panavia F2.0. The results reveal that zirconia surface treatments using GI+HF and MZ yield higher bond strength than those using APA or C, regardless of the resin cements.

  9. Bond strength of composite luting cement to zirconia ceramic surfaces.

    PubMed

    Derand, Tore; Molin, Margareta; Kvam, Ketil

    2005-12-01

    To evaluate the bond strength of dental resin agent to zirconia ceramic after surface pre-treatment with different techniques. Specimens of hot isostatic pressed yttrium-oxide-partially-stabilized zirconia blocks (ZF) were fabricated (Procera Zircon, Nobel Biocare, Sweden) and compared to glossy dense zirconia blocks (ZG). Four groups of specimens with different surface treatment were prepared. Group I: ZF (n = 5) and ZG (n = 5) without any pre-treatment, Group II: ZF-s (n = 5) and ZG-s (n = 5) treated with silane solution, Group III: ZF-P (n = 10) and ZG-P (n = 10) treated with RF plasma spraying (hexamethyldisiloxane) using a reactor (Plasma Electronic, Germany), Group IV: ZF-p (n = 10) and ZG-p (n = 10) treated with micro pearls of low fusing porcelain (720 degrees C) on the surfaces. Composite cylinders (Charisma, Hereus Kulzer, Dormagen, Germany) were luted with Variolink II (Ivoclar-Vivadent, Schaan, Liechtenstein) to the test specimens. The specimens were then stored in air for 1 h before shear loading in a universal testing machine (LRX, Lloyd Instruments, Farnham, England) until failure. No statistical difference was found between the untreated ZF and ZG specimens (Group I) neither between the specimens treated with silane (Group II). Plasma spraying treatment improved bond strength by a factor of three (p < 0.001). Treatment with low fusing porcelain micro pearls increased the bond strength by a factor of 10 compared to untreated surfaces (p < 0.001). No significant difference was seen between the surfaces treated ZF-p and ZG-p specimens. The thickness of the glass pearls layer did not exceed 5 microm. SEM showed dense grain borders of ZF and a flat glossy texture of ZG. Treatment of zirconia ceramic surfaces with plasma spraying or a low fusing porcelain pearl layer significantly increased the bond strength of resin cement to the ceramic surface.

  10. Identification of peptide motif that binds to the surface of zirconia.

    PubMed

    Hashimoto, Kazuhiko; Yoshinari, Masao; Matsuzaka, Kenichi; Shiba, Kiyotaka; Inoue, Takashi

    2011-01-01

    A zirconia-binding peptide motif was identified using a peptide phage display system. Yttria stabilized zirconia beads and discs were used as the target. Quartz crystal microbalance was used to monitor the binding of phages to zirconia. Starting from a library of phages displaying random sequences of 12-mer peptides, we repeated cycles of biopanning against zirconia beads. After four cycles of biopanning, we isolated a phage clone Φ#17. DNA sequencing of the corresponding portion of Φ#17 unexpectedly revealed that it displayed a 58-mer peptide (amino acid sequence: WMPSDVDINDPQGGGSRPNLHQPKPAAEAASKKKSENRKVPFYSHSWY-SSMSEDKRGW). We found that Φ#17 had a 300-fold, significantly higher binding affinity for zirconia discs than phages displaying no peptide. In quartz crystal microbalance assay, a rapid increase in energy dissipation was observed from Φ#17 but not from the control phages, indicating that Φ#17 binds to the surface of zirconia via its displayed peptide. We successfully identified a peptide motif that binds zirconia.

  11. Influence of a nanoporous zirconia implant surface of on cell viability of human osteoblasts.

    PubMed

    Aboushelib, Moustafa N; Osman, Essam; Jansen, Ineke; Everts, Vincent; Feilzer, Albert J

    2013-04-01

    The dense nonretentive surface of zirconia implants was modified into a nanoporous surface using selective infiltration etching surface treatment. The aim of this study was to investigate the influence of such a nanoporous modified zirconia surface on the attachment of human osteoblasts. Human osteoblasts were cultured for 21 days on (i) selective infiltration etched zirconia (nanoporous surface), (ii) polished zirconia, (iii) polished titanium, or (iv) airborne particle abraded acid etched (SLA) titanium disks. After the culture period the following parameters were assessed: number of cells, the morphology of the cells, the attachment of the cells, alkaline phosphatase activity, and the level of total protein (α= 0.05). Statistical analysis revealed a significantly higher cell count on the third (F = 17.4, p < 0.001) and eighth day (F = 163, p < 0.001) for nanoporous zirconia and SLA titanium surfaces compared to polished specimens. The number of cells (nanoporous zirconia 160 ± 20/mm(2) , SLA titanium 133 ± 15/mm(2) ) and cell size (nanoporous zirconia 50.7 ± 3 μm, SLA titanium 42.5 ± 4 μm) were significantly higher than polished specimens. Nanoporous zirconia specimens demonstrated comparable alkaline phosphatase activity (0.0036 ± 0.0035 ng/μl) and intracellular protein content (72.7 ± 0.9 ng/μl) compared to other tested groups. Scanning electron microscopy revealed that cells attached on the polished surface using finger-like processes, whereas on the nanoporous surface, finger-like processes were not observed, as the cell membrane appeared to be in close proximity to the underlying surface. The findings of this study suggest that a nanoporous zirconia surface favors cell growth and attachment compared to a polished surface. It was proposed that a nanoporous zirconia surface may improve clinical performance of zirconia implants. © 2013 by the American College of Prosthodontists.

  12. Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing.

    PubMed

    Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

    2014-12-01

    The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.

  13. Comparison of peri-implant bone formation around injection-molded and machined surface zirconia implants in rabbit tibiae.

    PubMed

    Kim, Hong-Kyun; Woo, Kyung Mi; Shon, Won-Jun; Ahn, Jin-Soo; Cha, Seunghee; Park, Young-Seok

    2015-01-01

    The aim of this study was to compare osseointegration and surface characteristics of zirconia implants made by the powder injection molding (PIM) technique against those made by the conventional milling procedure in rabbit tibiae. Surface characteristics of 2 types of implants were evaluated. Sixteen rabbits received 2 types of external hex implants with similar geometry, either machined zirconia implants or PIM zirconia implants, in the tibiae. Removal torque tests and histomorphometric analyses were performed. The roughness of the PIM zirconia implants was higher than that of machined zirconia implants. The PIM zirconia implants exhibited significantly higher bone-implant contact and removal torque values than the machined zirconia implants (p<0.001). The osseointegration of the PIM zirconia implant is promising, and PIM, using the roughened mold etching technique, can produce substantially rougher surfaces on zirconia implants.

  14. Influence of surface modification techniques on shear bond strength between different zirconia cores and veneering ceramics

    PubMed Central

    Rismanchian, Mansour; Savabi, Omid; Ashtiani, Alireza Hashemi

    2011-01-01

    PURPOSE Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 µm Al2O3 particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T-test were selected to analyzed the data (α=0.05). RESULTS In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain. PMID:22259706

  15. Mechanical behavior of yttria-stabilized tetragonal zirconia polycrystalline ceramic after different zirconia surface treatments.

    PubMed

    Pozzobon, Joao Luiz; Pereira, Gabriel Kalil Rocha; Wandscher, Vinicius Felipe; Dorneles, Lucio Strazzabosco; Valandro, Luiz Felipe

    2017-08-01

    This study investigated the effects of different zirconia surface conditioning methods on the biaxial flexure strength, surface characteristics and fractographic analysis of a Y-TZP ceramic. Disc-shaped specimens were manufactured according to ISO 6872-2008 for biaxial flexure strength testing, and then randomly assigned into seven groups (n=30). Control (CTRL): without treatment; Tribochemical silica coating (TBS): specimens were sandblasted with silica-coated aluminum oxide particles (CoJet-Sand) for 10s; Silica nanofilm (SNF): specimens were silica coated with a 5nm SiO2 nanofilm; and four protocols of low-fusing porcelain glaze (GLZ): etching with 10% hydrofluoric acid gel (HF) for 1min (GLZ1), 5min (GLZ5), 10min (GLZ10) and 15min (GLZ15). Phase transformation, roughness, micro-morphological, flexural analysis tests, and fractographic analyses were performed. X-ray diffraction (XRD) analysis showed that the TBS promoted the highest m-phase content (20.35). However, for the GLZ groups, XRD analysis was not sensitive enough to obtain an accurate reading for phase transformation. The GLZ group had the highest roughness values. The TBS group had the highest characteristic strength (1291.38MPa), followed by SNF (999.26MPa). These results suggest that (TBS) and (SNF) treatments did not reduce the mechanical properties, while (GLZ) led to a degradation in the mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Effect of Zirconia Dental Implant Surfaces on Bone Integration: A Systematic Review and Meta-Analysis

    PubMed Central

    2017-01-01

    Background. The information available about osseointegration and the bone to implant interaction of zirconia implants with various surface modifications is still far from sufficient. Objective. The purpose of this systematic review and meta-analysis was to evaluate and compare zirconia dental implants with different surface topographies, with a focus on bone to implant contact and removal torque. Methods. The systematic review of the extracted publications was performed to compare the bone to implant contact (BIC) with removal torque (RT) values of titanium dental implants and machined and surfaced modified zirconia implants. Results. A total of fifteen articles on BIC and RT values were included in the quantitative analysis. No significant difference in the BIC values was observed between titanium and machined zirconia implants (p = 0.373; 95% CI: −0.166 to 0.443). However, a significantly better BIC values were observed for acid etched zirconia implants compared with those of titanium implants (p = 0.032; 95% CI: 0.068 to 1.461). Unmodified zirconia implants showed favorable BIC values compared to modified-surface zirconia implants (p = 0.021; 95% CI: −0.973 to −0.080). Conclusion. Acid etched zirconia implants may serve as a possible substitute for successful osseointegration. PMID:28299337

  17. Effect of Zirconia Dental Implant Surfaces on Bone Integration: A Systematic Review and Meta-Analysis.

    PubMed

    Hafezeqoran, Ali; Koodaryan, Roodabeh

    2017-01-01

    Background. The information available about osseointegration and the bone to implant interaction of zirconia implants with various surface modifications is still far from sufficient. Objective. The purpose of this systematic review and meta-analysis was to evaluate and compare zirconia dental implants with different surface topographies, with a focus on bone to implant contact and removal torque. Methods. The systematic review of the extracted publications was performed to compare the bone to implant contact (BIC) with removal torque (RT) values of titanium dental implants and machined and surfaced modified zirconia implants. Results. A total of fifteen articles on BIC and RT values were included in the quantitative analysis. No significant difference in the BIC values was observed between titanium and machined zirconia implants (p = 0.373; 95% CI: -0.166 to 0.443). However, a significantly better BIC values were observed for acid etched zirconia implants compared with those of titanium implants (p = 0.032; 95% CI: 0.068 to 1.461). Unmodified zirconia implants showed favorable BIC values compared to modified-surface zirconia implants (p = 0.021; 95% CI: -0.973 to -0.080). Conclusion. Acid etched zirconia implants may serve as a possible substitute for successful osseointegration.

  18. Cell attachment and proliferation of bone marrow-derived osteoblast on zirconia of various surface treatment

    PubMed Central

    Lee, Heesu; Noh, Kwantae; Woo, Yi-Hyung

    2014-01-01

    PURPOSE This study was performed to characterize the effects of zirconia coated with calcium phosphate and hydroxyapatite compared to smooth zirconia after bone marrow-derived osteoblast culture. MATERIALS AND METHODS Bone marrow-derived osteoblasts were cultured on (1) smooth zirconia, (2) zirconia coated with calcium phosphate (CaP), and (3) zirconia coated with hydroxyapatite (HA). The tetrazolium-based colorimetric assay (MTT test) was used for cell proliferation evaluation. Scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cellular morphology and differentiation rate. X-ray photoelectron spectroscopy (XPS) was employed for the analysis of surface chemistry. The genetic expression of the osteoblasts and dissolution behavior of the coatings were observed. Assessment of the significance level of the differences between the groups was done with analysis of variance (ANOVA). RESULTS From the MTT assay, no significant difference between smooth and surface coated zirconia was found (P>.05). From the SEM image, cells on all three groups of discs were sporadically triangular or spread out in shape with formation of filopodia. From the ALP activity assay, the optical density of osteoblasts on smooth zirconia discs was higher than that on surface treated zirconia discs (P>.05). Most of the genes related to cell adhesion showed similar expression level between smooth and surface treated zirconia. The dissolution rate was higher with CaP than HA coating. CONCLUSION The attachment and growth behavior of bone-marrow-derived osteoblasts cultured on smooth surface coated zirconia showed comparable results. However, the HA coating showed more time-dependent stability compared to the CaP coating. PMID:24843393

  19. Response of osteoblast-like SAOS-2 cells to zirconia ceramics with different surface topographies.

    PubMed

    Hempel, Ute; Hefti, Thomas; Kalbacova, Marie; Wolf-Brandstetter, Cornelia; Dieter, Peter; Schlottig, Falko

    2010-02-01

    Zirconia is a suitable biomaterial for use in medicine (stomatology, orthopaedics) due to its good biocompatibility and outstanding mechanical properties. This study compares the effect of (i) zirconia to the widely used titanium and (ii) zirconia with two different surface topographies (sandblasted and sandblasted/etched) on the adhesion, proliferation and differentiation of SAOS-2 osteoblasts. SAOS-2 cells were cultured on either sandblasted or sandblasted/etched zirconia and compared with sandblasted/etched titanium. 2 and 24 h after plating, cell morphology was investigated by scanning electron microscope (SEM) and fluorescence imaging. At 24 and 48 h, cell number-relevant parameters were determined. Alkaline phosphatase (ALP) activity and mineral accumulation were measured at days 8, 11, 15 and day 22 of culture, respectively. SEM and fluorescence images revealed a faster spreading as well as higher number of adherent cells after 24 h incubation on zirconia compared with titanium. Also, the cellular metabolic activity after 24 h and the proliferation rate after 48 h is higher with zirconia compared with titanium. Zirconia had a more pronounced effect compared with titanium on the differentiation of SAOS-2 cells: ALP activity, an early differentiation marker increased earlier and mineralization, a late differentiation marker was increased. Only minor differences were found between zirconia with two different surface topographies; etched zirconia promoted slightly greater the differentiation of SAOS-2 cells. These data indicate that zirconia mediates a pronounced stronger effect on the adhesion, proliferation and differentiation compared with titanium; and that topographical differences of zirconia have minor effects on osteoblast biology.

  20. Formation of metastable tetragonal zirconia nanoparticles: Competitive influence of the dopants and surface state

    SciTech Connect

    Gorban, Oksana; Synyakina, Susanna; Volkova, Galina; Gorban, Sergey; Konstantiova, Tetyana; Lyubchik, Svetlana

    2015-12-15

    The effect of the surface modification of the nanoparticles of amorphous and crystalline partially stabilized zirconia by fluoride ions on stability of the metastable tetragonal phase was investigated. Based on the DSC, titrimetry and FTIR spectroscopy data it was proven that surface modification of the xerogel resulted from an exchange of the fluoride ions with the basic OH groups. The effect of the powder pre-calcination temperature before modification on the formation of metastable tetragonal phase in partially stabilized zirconia was investigated. It was shown that the main factor of tetragonal zirconia stabilization is the state of nanoparticles surface at pre-crystallization temperatures.

  1. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic.

    PubMed

    Moradabadi, Ashkan; Roudsari, Sareh Esmaeily Sabet; Yekta, Bijan Eftekhari; Rahbar, Nima

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30× magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments. © 2013.

  2. Wear performance of bovine tooth enamel against translucent tetragonal zirconia polycrystals after different surface treatments.

    PubMed

    Hara, Mai; Takuma, Yusuke; Sato, Toru; Koyama, Taku; Yoshinari, Masao

    2014-01-01

    The wear performances of bovine tooth enamel (BTE) against translucent tetragonal zirconia polycrystals (TZP) compared to that of feldspar porcelain and the influence of surface treatments of translucent TZP were investigated by the two-body wear test. Translucent TZP and feldspar porcelain were used as hemisphere abrader specimens with a radius of curvature of 5 mm; flat BTE surfaces were used as substrate specimens. The cross-sectional area of the worn surfaces of the substrates and the wear volume of the antagonist abraders were measured. Surface roughness, hardness and coefficient of friction as well as SEM observations and EPMA analyses were also performed to investigate the underlying mechanism of wear. The results suggested that BTE is less susceptible to wear when translucent TZP is used as the antagonist in contrast to the use of feldspar porcelain, and that surface treatment of the TZP abraders significantly influenced the wear of BTE substrates.

  3. Influence of Surface Properties on Adhesion Forces and Attachment of Streptococcus mutans to Zirconia In Vitro.

    PubMed

    Yu, Pei; Wang, Chuanyong; Zhou, Jinglin; Jiang, Li; Xue, Jing; Li, Wei

    2016-01-01

    Zirconia is becoming a prevalent material in dentistry. However, any foreign bodies inserted may provide new niches for the bacteria in oral cavity. The object of this study was to explore the effect of surface properties including surface roughness and hydrophobicity on the adhesion and biofilm formation of Streptococcus mutans (S. mutans) to zirconia. Atomic force microscopy was employed to determine the zirconia surface morphology and the adhesion forces between the S. mutans and zirconia. The results showed that the surface roughness was nanoscale and significantly different among tested groups (P < 0.05): Coarse (23.94 ± 2.52 nm) > Medium (17.00 ± 3.81 nm) > Fine (11.89 ± 1.68 nm). The contact angles of the Coarse group were the highest, followed by the Medium and the Fine groups. Increasing the surface roughness and hydrophobicity resulted in an increase of adhesion forces and early attachment (2 h and 4 h) of S. mutans on the zirconia but no influence on the further development of biofilm (6 h~24 h). Our findings suggest that the surface roughness in nanoscale and hydrophobicity of zirconia had influence on the S. mutans initial adhesion force and early attachment instead of whole stages of biofilm formation.

  4. Influence of Surface Properties on Adhesion Forces and Attachment of Streptococcus mutans to Zirconia In Vitro

    PubMed Central

    Yu, Pei; Wang, Chuanyong; Zhou, Jinglin; Jiang, Li

    2016-01-01

    Zirconia is becoming a prevalent material in dentistry. However, any foreign bodies inserted may provide new niches for the bacteria in oral cavity. The object of this study was to explore the effect of surface properties including surface roughness and hydrophobicity on the adhesion and biofilm formation of Streptococcus mutans (S. mutans) to zirconia. Atomic force microscopy was employed to determine the zirconia surface morphology and the adhesion forces between the S. mutans and zirconia. The results showed that the surface roughness was nanoscale and significantly different among tested groups (P < 0.05): Coarse (23.94 ± 2.52 nm) > Medium (17.00 ± 3.81 nm) > Fine (11.89 ± 1.68 nm). The contact angles of the Coarse group were the highest, followed by the Medium and the Fine groups. Increasing the surface roughness and hydrophobicity resulted in an increase of adhesion forces and early attachment (2 h and 4 h) of S. mutans on the zirconia but no influence on the further development of biofilm (6 h~24 h). Our findings suggest that the surface roughness in nanoscale and hydrophobicity of zirconia had influence on the S. mutans initial adhesion force and early attachment instead of whole stages of biofilm formation. PMID:27975061

  5. Shear bond strength of veneering porcelain to zirconia: Effect of surface treatment by CNC-milling and composite layer deposition on zirconia.

    PubMed

    Santos, R L P; Silva, F S; Nascimento, R M; Souza, J C M; Motta, F V; Carvalho, O; Henriques, B

    2016-07-01

    The purpose of this study was to evaluate the shear bond strength of veneering feldspathic porcelain to zirconia substrates modified by CNC-milling process or by coating zirconia with a composite interlayer. Four types of zirconia-porcelain interface configurations were tested: RZ - porcelain bonded to rough zirconia substrate (n=16); PZ - porcelain bonded to zirconia substrate with surface holes (n=16); RZI - application of a composite interlayer between the veneering porcelain and the rough zirconia substrate (n=16); PZI - application of a composite interlayer between the porcelain and the zirconia substrate treated by CNC-milling (n=16). The composite interlayer was composed of zirconia particles reinforced porcelain (30%, vol%). The mechanical properties of the ceramic composite have been determined. The shear bond strength test was performed at 0.5mm/min using a universal testing machine. The interfaces of fractured and untested specimens were examined by FEG-SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The one-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results (α=0.05). The shear bond strength of PZ (100±15MPa) and RZI (96±11MPa) specimens were higher than that recorded for RZ (control group) specimens (89±15MPa), although not significantly (p>0.05). The highest shear bond strength values were recorded for PZI specimens (138±19MPa), yielding a significant improvement of 55% relative to RZ specimens (p<0.05). This study shows that it is possible to highly enhance the zirconia-porcelain bond strength - even by ~55% - by combining surface holes in zirconia frameworks and the application of a proper ceramic composite interlayer. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Microshear bond strength evaluation of surface pretreated zirconia ceramics bonded to dentin

    PubMed Central

    Anand, Shenbagakuttalam; Ebenezar, Ambrose Vedamanickam Rajesh; Anand, Nirupa; Rajkumar, Kothandaraman; Mahalaxmi, Sekar; Srinivasan, Narasimhan

    2015-01-01

    Objectives: To comparatively assess the micro shear bond strength (MSBS) of dentin bonded surface pre-treated zirconia ceramics. Materials and Methods: Zirconia blocks were sectioned into 50 cubical blocks. The blocks were further categorized into five groups (n = 10 each). Group I: No treatment was performed on zirconia samples; Group II: The zirconia samples were sand-blasted; Group III: Group II + etched with 9.8% of hydrofluoric (HF) acid for 60 s; Group IV: The sandblasted zirconia samples were selectively infiltrated with low fusing porcelain; and Group V: Group IV + etched using 9.8% HF acid gel. The zirconia specimens were then bonded to dentin samples, and the samples were tested for MSBS evaluation using universal testing machine. Results: The MSBS of all the four experimental groups shows greater value than group I. Among the experimental groups, group V and group IV do not show any statistical significant difference, whereas the mean MSBS of groups IV and V were statistically greater than group III and group II. However, groups I, II, and III do not show any statistical significant difference in mean MSBS values between them. Conclusion: Selective infiltration etching of zirconia ceramics provides the highest bond strength with resin cement. PMID:26038654

  7. Microstructured zirconia surfaces modulate osteogenic marker genes in human primary osteoblasts.

    PubMed

    Bergemann, Claudia; Duske, Kathrin; Nebe, J Barbara; Schöne, André; Bulnheim, Ulrike; Seitz, Hermann; Fischer, Jens

    2015-01-01

    In dentistry, zirconia has been used since the early 1990s for endodontic posts, more recently for implant abutments and frameworks for fixed dental prostheses. Zirconia is biocompatible and mechanically strong enough to serve as implant material for oral implants. Although several zirconia implant systems are available, currently the scientific and clinical data for zirconia implants are not sufficient to recommend them for routine clinical use. Here the influence of microstructured yttria-stabilized zirconia (YZ) on human primary osteoblast (HOB) behavior was determined. YZ surfaces were treated by sandblasting (YZ-S), acid etching (YZ-SE) and additionally heat treatment (YZ-SEH). Morphological changes of HOB were determined by scanning electron microscopy. Actin cytoskeleton was investigated by laser scanning microscopy and analyzed by novel actin quantification software. Differentiation of HOB was determined by real time RT-PCR. Improved mechanical interlocking of primary HOB into the porous microstructure of the acid etched and additionally heat treated YZ-surfaces correlates with drastically increased osteocalcin (OCN) gene expression. In particular, OCN was considerably elevated in primary HOB after 3 days on YZ-SE (13-fold) as well as YZ-SEH (12-fold) surfaces. Shorter actin filaments without any favored orientation on YZ-SE and YZ-SEH surfaces are associated with higher roughness (Ra) values. Topographically modified yttria-stabilized zirconia is a likely material for dental implants with cell stimulating properties achieving or actually exceeding those of titanium.

  8. Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces

    PubMed Central

    Depprich, Rita; Ommerborn, Michelle; Zipprich, Holger; Naujoks, Christian; Handschel, Jörg; Wiesmann, Hans-Peter; Kübler, Norbert R; Meyer, Ulrich

    2008-01-01

    Background Osseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility make zirconia a suitable material for dental implants, although surface processings are still problematic. The aim of the present study was to compare osteoblast behavior on structured zirconia and titanium surfaces under standardized conditions. Methods The surface characteristics were determined by scanning electron microscopy (SEM). In primary bovine osteoblasts attachment kinetics, proliferation rate and synthesis of bone-associated proteins were tested on different surfaces. Results The results demonstrated that the proliferation rate of cells was significantly higher on zirconia surfaces than on titanium surfaces (p < 0.05; Student's t-test). In contrast, attachment and adhesion strength of the primary cells was significant higher on titanium surfaces (p < 0.05; U test). No significant differences were found in the synthesis of bone-specific proteins. Ultrastructural analysis revealed phenotypic features of osteoblast-like cells on both zirconia and titanium surfaces. Conclusion The study demonstrates distinct effects of the surface composition on osteoblasts in culture. Zirconia improves cell proliferation significantly during the first days of culture, but it does not improve attachment and adhesion strength. Both materials do not differ with respect to protein synthesis or ultrastructural appearance of osteoblasts. Zirconium oxide may therefore be a suitable material for dental implants. PMID:19063728

  9. Impact of surface roughness of gypsum materials on adaptation of zirconia cores.

    PubMed

    Kim, Ki-Baek; Kim, Jae-Hong; Kim, Sa-Hak

    2015-06-01

    The present study investigated the influences of various gypsum materials on the precision of fit of CAD/CAM-fabricated prostheses and analyzed their correlation with surface roughness. The master model of the mandibular right first molar was replicated, and four experimental groups based on two types of Type IV stone (GC Fujirock EP, Die keen) and two types of scannable stone (Aesthetic-Basegold, Everest Rock) were created to include a total of 40 specimens, 10 in each group. The surface roughness of the working models for the respective experimental groups was measured. Once the zirconia cores had been fabricated, the marginal and internal fits were measured with a digital microscope using the silicone replica technique. The mean and standard deviation of the respective points of measurement were computed and analyzed through the one-way ANOVA and Tukey's HSD test. The correlation between surface roughness and the precision of fit of the zirconia core was analyzed using the Pearson correlation analysis (α=.05). The zirconia cores fabricated from the scannable stone working models exhibited a superior precision of fit as compared to those fabricated from the Type IV stone working models. The correlation analysis results showed a clear positive correlation between surface roughness and the precision of fit of zirconia cores in all of the experimental groups (P<.05). The results confirmed that the surface roughness of dental working models has a decisive influence on the precision of fit of zirconia cores.

  10. Microstructure, bioactivity and osteoblast behavior of monoclinic zirconia coating with nanostructured surface.

    PubMed

    Wang, Guocheng; Meng, Fanhao; Ding, Chuanxian; Chu, Paul K; Liu, Xuanyong

    2010-03-01

    A monoclinic zirconia coating with a nanostructural surface was prepared on the Ti-6Al-4V substrate by an atmospheric plasma-spraying technique, and its microstructure and composition, as well as mechanical and biological properties, were investigated to explore potential application as a bioactive coating on bone implants. X-ray diffraction, transmission electron microscopy, scanning electron microscopy and Raman spectroscopy revealed that the zirconia coating was composed of monoclinic zirconia which was stable at low temperature, and its surface consists of nano-size grains 30-50 nm in size. The bond strength between the coating and the Ti-6Al-4V substrate was 48.4 + or - 6.1 MPa, which is higher than that of plasma-sprayed HA coatings. Hydrothermal experiments indicated that the coating was stable in a water environment and the phase composition and Vickers hardness were independent of the hydrothermal treatment time. Bone-like apatite is observed to precipitate on the surface of the coating after soaking in simulated body fluid for 6 days, indicating excellent bioactivity in vitro. The nanostructured surface composed of monoclinic zirconia is believed to be crucial to its bioactivity. Morphological observation and the cell proliferation test demonstrated that osteoblast-like MG63 cells could attach to, adhere to and proliferate well on the surface of the monoclinic zirconia coating, suggesting possible applications in hard tissue replacements.

  11. Impact of surface roughness of gypsum materials on adaptation of zirconia cores

    PubMed Central

    Kim, Ki-Baek; Kim, Sa-Hak

    2015-01-01

    PURPOSE The present study investigated the influences of various gypsum materials on the precision of fit of CAD/CAM-fabricated prostheses and analyzed their correlation with surface roughness. MATERIALS AND METHODS The master model of the mandibular right first molar was replicated, and four experimental groups based on two types of Type IV stone (GC Fujirock EP, Die keen) and two types of scannable stone (Aesthetic-Basegold, Everest Rock) were created to include a total of 40 specimens, 10 in each group. The surface roughness of the working models for the respective experimental groups was measured. Once the zirconia cores had been fabricated, the marginal and internal fits were measured with a digital microscope using the silicone replica technique. The mean and standard deviation of the respective points of measurement were computed and analyzed through the one-way ANOVA and Tukey's HSD test. The correlation between surface roughness and the precision of fit of the zirconia core was analyzed using the Pearson correlation analysis (α=.05). RESULTS The zirconia cores fabricated from the scannable stone working models exhibited a superior precision of fit as compared to those fabricated from the Type IV stone working models. The correlation analysis results showed a clear positive correlation between surface roughness and the precision of fit of zirconia cores in all of the experimental groups (P<.05). CONCLUSION The results confirmed that the surface roughness of dental working models has a decisive influence on the precision of fit of zirconia cores. PMID:26140171

  12. Bonding of Metal Orthodontic Attachments to Sandblasted Porcelain and Zirconia Surfaces

    PubMed Central

    2016-01-01

    This study evaluates tensile bond strength (TBS) of metal orthodontic attachments to sandblasted feldspathic porcelain and zirconia with various bonding protocols. Thirty-six (36) feldspathic and 36 zirconia disc samples were prepared, glazed, embedded in acrylic blocks and sandblasted, and divided into three groups according to one or more of the following treatments: hydrofluoric acid 4% (HF), Porcelain Conditioner silane primer, Reliance Assure® primer, Reliance Assure plus® primer, and Z Prime™ plus zirconia primer. A round traction hook was bonded to each sample. Static tensile bond strength tests were performed in a universal testing machine and adhesive remnant index (ARI) scoring was done using a digital camera. One-way ANOVA and Pearson chi-square tests were used to analyze TBS (MPa) and ARI scores. No statistically significant mean differences were found in TBS among the different bonding protocols for feldspathic and zirconia, p values = 0.369 and 0.944, respectively. No statistically significant distribution of ARI scores was found among the levels of feldspathic, p value = 0.569. However, statistically significant distribution of ARI scores was found among the levels of zirconia, p value = 0.026. The study concluded that silanization following sandblasting resulted in tensile bond strengths comparable to other bonding protocols for feldspathic and zirconia surface. PMID:27747233

  13. Bonding of Metal Orthodontic Attachments to Sandblasted Porcelain and Zirconia Surfaces.

    PubMed

    Mehta, Amitoj S; Evans, Carla A; Viana, Grace; Bedran-Russo, Ana; Galang-Boquiren, Maria Therese S

    2016-01-01

    This study evaluates tensile bond strength (TBS) of metal orthodontic attachments to sandblasted feldspathic porcelain and zirconia with various bonding protocols. Thirty-six (36) feldspathic and 36 zirconia disc samples were prepared, glazed, embedded in acrylic blocks and sandblasted, and divided into three groups according to one or more of the following treatments: hydrofluoric acid 4% (HF), Porcelain Conditioner silane primer, Reliance Assure® primer, Reliance Assure plus® primer, and Z Prime™ plus zirconia primer. A round traction hook was bonded to each sample. Static tensile bond strength tests were performed in a universal testing machine and adhesive remnant index (ARI) scoring was done using a digital camera. One-way ANOVA and Pearson chi-square tests were used to analyze TBS (MPa) and ARI scores. No statistically significant mean differences were found in TBS among the different bonding protocols for feldspathic and zirconia, p values = 0.369 and 0.944, respectively. No statistically significant distribution of ARI scores was found among the levels of feldspathic, p value = 0.569. However, statistically significant distribution of ARI scores was found among the levels of zirconia, p value = 0.026. The study concluded that silanization following sandblasting resulted in tensile bond strengths comparable to other bonding protocols for feldspathic and zirconia surface.

  14. Spontaneous Rippling and Subsequent Polymer Molding on Yttria-Stabilized Zirconia (110) Surfaces.

    PubMed

    Ansari, Haris M; Niu, Zhiyuan; Ge, Chen; Dregia, Suliman A; Akbar, Sheikh A

    2017-02-28

    Spontaneous nanoripple formation on (110) surfaces of yttria-stabilized zirconia, YSZ-(110), is achieved by diffusional surface doping with rare-earth oxides. Periodic arrays of parallel nanobars separated by channels (period ∼100 nm) grow out of the dopant sources, covering relatively wide areas of the surface (∼10 μm). The nanobars mound up on the surface by diffusion, exhibiting morphological uniformity and alignment, with their long axis lying parallel to the [11̅0] direction in the YSZ-(110) surface. The process for forming these nanobar arrays can be as simple as sprinkling of rare-earth oxide powder (dopant source) on YSZ-(110) surface and annealing in a high temperature air furnace. However, higher control on dopant dispersion on the surface is demonstrated with other techniques, including photolithography and inkjet printing. The ripple arrays extend anisotropically on the (110) surface, obeying the parabolic growth law, and showing principal values of the rate constant along [11̅0] (maximum) and [001] (minimum), as expected from the symmetry of the (110) surface. The self-patterned ceramic substrates are well-suited for pattern transfer by replica molding, as illustrated by single-step molding with polydimethylsiloxane (PDMS), which is a widely used biomaterial in cell-culture studies.

  15. Surface characterization of acidic ceria-zirconia prepared by direct sulfation

    NASA Astrophysics Data System (ADS)

    Azambre, B.; Zenboury, L.; Weber, J. V.; Burg, P.

    2010-05-01

    Acidic ceria-zirconia (SCZ) solid acid catalysts with a nominal surface density of ca 2 SO 42-/nm 2 were prepared by a simple route consisting in soaking high specific surface area Ce xZr 1- xO 2 (with x = 0.21 and 0.69) mixed oxides solutions in 0.5 M sulphuric acid. Characterizations by TPD-MS, TP-DRIFTS and FT-Raman revealed that most of surface structures generated by sulfation are stable at least up to 700 °C under inert atmosphere and consist mainly as isolated sulfates located on defects or crystal planes and to a lesser extent as polysulfates. Investigations by pyridine adsorption/desorption have stated that: SCZ possess both strong Brønsted (B) and Lewis (L) acid sites, some of them being presumably superacidic; the B/L site ratio was found to be more dependent on the temperature and hydration degree than on the composition of the ceria-zirconia. By contrast, the reactivity of the parent Ce xZr 1- xO 2 materials towards pyridine is mostly driven by redox properties resulting in the formation of Py-oxide with the participation of Lewis acid sites of moderate strength ( cus Ce x+ and Zr x+ cations). Basicity studies by CO 2 adsorption/desorption reveal that SCZ surfaces are solely acidic whereas the number and strength of Lewis basic sites increases with the Ce content for the parent Ce xZr 1- xO 2 materials.

  16. Clinical and laboratory surface finishing procedures for zirconia on opposing human enamel wear: A laboratory study.

    PubMed

    Chong, Bevan J; Thangavel, Arun K; Rolton, Shane B; Guazzato, Massimiliano; Klineberg, Iven J

    2015-10-01

    To investigate the effect of laboratory and clinical finishing procedures for zirconia on antagonistic enamel wear. Forty-eight yttria-tetragonal partially stabilised zirconia (Y-TZP) specimens were prepared and divided into four groups according to their surface preparation: laboratory polished (LP); laboratory polished and glazed (G); clinically adjusted (CA); and clinically adjusted and repolished (CAR). Enamel opposing enamel was used as a control. Pre-testing surface roughness for each group was determined using contact profilometry. Two-body wear resistance tests were conducted using a masticatory simulator. Enamel specimens were subjected to 120,000 cycles in distilled water (frequency 1.6 Hz, loading force of 49 N). Volumetric and vertical enamel losses were measured by superimposition of pre- and post-testing images using a three-dimensional laser scanner and software analysis. Scanning electron microscopy was used for qualitative surface analysis of pre- and post-testing zirconia and enamel surfaces. One-way ANOVA and multiple comparisons with Bonferroni corrections were used for statistical analysis at a significance level of α=0.05. There was no statistical difference in volumetric and vertical enamel loss between CAR, G and LP. CAR produced statistically significantly less volumetric enamel loss compared with CA and control, and statistically significantly less vertical enamel loss compared with CA. Volumetric and vertical enamel loss were highly correlated in all groups. Enamel wear by clinically ground zirconia is comparable to that of opposing enamel surfaces and greater than clinically repolished zirconia. Repolishing of zirconia restorations following clinical adjustment with diamond burs is effective in reducing antagonistic enamel wear. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Bottom-up engineering of the surface roughness of nanostructured cubic zirconia to control cell adhesion.

    PubMed

    Singh, A V; Ferri, M; Tamplenizza, M; Borghi, F; Divitini, G; Ducati, C; Lenardi, C; Piazzoni, C; Merlini, M; Podestà, A; Milani, P

    2012-11-30

    Nanostructured cubic zirconia is a strategic material for biomedical applications since it combines superior structural and optical properties with a nanoscale morphology able to control cell adhesion and proliferation. We produced nanostructured cubic zirconia thin films at room temperature by supersonic cluster beam deposition of nanoparticles produced in the gas phase. Precise control of film roughness at the nanoscale is obtained by operating in a ballistic deposition regime. This allows one to study the influence of nanoroughness on cell adhesion, while keeping the surface chemistry constant. We evaluated cell adhesion on nanostructured zirconia with an osteoblast-like cell line using confocal laser scanning microscopy for detailed morphological and cytoskeleton studies. We demonstrated that the organization of cytoskeleton and focal adhesion formation can be controlled by varying the evolution of surface nanoroughness.

  18. The effect of various sandblasting conditions on surface changes of dental zirconia and shear bond strength between zirconia core and indirect composite resin.

    PubMed

    Su, Naichuan; Yue, Li; Liao, Yunmao; Liu, Wenjia; Zhang, Hai; Li, Xin; Wang, Hang; Shen, Jiefei

    2015-06-01

    To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and 110 µm. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (α=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 µm to 110 µm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 µm is recommended for dental applications to improve the bonding between zirconia core and ICR.

  19. The effect of various sandblasting conditions on surface changes of dental zirconia and shear bond strength between zirconia core and indirect composite resin

    PubMed Central

    Su, Naichuan; Yue, Li; Liao, Yunmao; Liu, Wenjia; Zhang, Hai; Li, Xin

    2015-01-01

    PURPOSE To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and 110 µm. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (α=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 µm to 110 µm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 µm is recommended for dental applications to improve the bonding between zirconia core and ICR. PMID:26140173

  20. Effect of hydrofluoric acid concentration and etching duration on select surface roughness parameters for zirconia.

    PubMed

    Smielak, Beata; Klimek, Leszek

    2015-06-01

    The surface of zirconia is resistant to chemical treatment. Roughening the surface of densely sintered zirconia still poses a challenge in dentistry. The purpose of the study was to examine the effects of hydrofluoric acid on the quality of surface roughening of zirconia. One hundred cylindrical disks made from zirconia (Ceramill Zi; Amann Girrbach AG) were divided into 4 groups. Three groups (n=30) were distinguished on the basis of hydrofluoric acid (HF) concentration: 40% HF, 9.5% HF, and 5% HF. The groups were then further divided into 3 groups of 10 specimens, each based on etch time (1, 5, or 15 minutes). The control group (n=10) consisted of specimens polished with SiC abrasive paper. The surface was examined with scanning electron microscopy, and the roughness was measured with a profilometer and confocal laser scanning microscope. The mean arithmetic profile deviation (Ra(mean)) and mean maximum height of profile (Rz(mean)) results for the etched surfaces in relationship to the baseline surfaces were compared with the Student t test for averaged data (α=.05). When etched with 40% HF concentration, the Ra(mean) and Rz(mean) results were statistically higher (P<.01) for the etched surfaces than for the baseline surfaces. When etched with 9.5% HF concentration, the higher Ra(mean) and Rz(mean) results were only statistically significant (P<.01) after 15 minutes. Etching with 5% HF concentration showed no significant differences (P>.05). Etching with a 5% HF solution should not be recommended as a method for roughening zirconia surfaces. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Roughness gradients on zirconia for rapid screening of cell-surface interactions: Fabrication, characterization and application.

    PubMed

    Flamant, Quentin; Stanciuc, Ana-Maria; Pavailler, Hugo; Sprecher, Christoph Martin; Alini, Mauro; Peroglio, Marianna; Anglada, Marc

    2016-10-01

    Roughness is one of the key parameters for successful osseointegration of dental implants. The understanding of how roughness affects cell response is thus crucial to improve implant performance. Surface gradients, which allow rapid and systematic investigations of cell-surface interactions, have the potential to facilitate this task. In this study, a novel method aiming to produce roughness gradients at the surface of zirconia using hydrofluoric acid etching was implemented. The topography was exhaustively characterized at the microscale and nanoscale by white light interferometry and atomic force microscopy, including the analysis of amplitude, spatial, hybrid, functional, and fractal parameters. A rapid screening of the influence of roughness on human mesenchymal stem cell morphology was conducted and potential correlations between roughness parameters and cell morphology were investigated. The roughness gradient induced significant changes in cell area (p < 0.001), aspect ratio (p = 0.01), and solidity (p = 0.026). Nanoroughness parameters were linearly correlated to cell solidity (p < 0.005), while microroughness parameters appeared nonlinearly correlated to cell area, highlighting the importance of multiscale optimization of implant topography to induce the desired cell response. The gradient method proposed here drastically reduces the efforts and resources necessary to study cell-surface interactions and provides results directly transferable to industry. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2502-2514, 2016. © 2016 Wiley Periodicals, Inc.

  2. Influence of Hot-Etching Surface Treatment on Zirconia/Resin Shear Bond Strength

    PubMed Central

    Lv, Pin; Yang, Xin; Jiang, Ting

    2015-01-01

    This study was designed to evaluate the effect of hot-etching surface treatment on the shear bond strength between zirconia ceramics and two commercial resin cements. Ceramic cylinders (120 units; length: 2.5 mm; diameter: 4.7 mm) were randomly divided into 12 groups (n = 10) according to different surface treatments (blank control; airborne-particle-abrasion; hot-etching) and different resin cements (Panavia F2.0; Superbond C and B) and whether or not a thermal cycling fatigue test (5°–55° for 5000 cycles) was performed. Flat enamel surfaces, mounted in acrylic resin, were bonded to the zirconia discs (diameter: 4.7 mm). All specimens were subjected to shear bond strength testing using a universal testing machine with a crosshead speed of 1 mm/min. All data were statistically analyzed using one-way analysis of variance and multiple-comparison least significant difference tests (α = 0.05). Hot-etching treatment produced higher bond strengths than the other treatment with both resin cements. The shear bond strength of all groups significantly decreased after the thermal cycling test; except for the hot-etching group that was cemented with Panavia F2.0 (p < 0.05). Surface treatment of zirconia with hot-etching solution enhanced the surface roughness and bond strength between the zirconia and the resin cement. PMID:28793699

  3. Effect of airborne-particle abrasion of presintered zirconia on surface roughness and bacterial adhesion.

    PubMed

    Zhang, Ming; Zhang, Zutai; Ding, Ning; Zheng, Dongxiang

    2015-05-01

    Factors associated with implant periodontal disease of zirconia restorations such as surface roughness remain largely unknown. The purpose of this study was to investigate how airborne-particle abrasion before sintering affects roughness and bacterial adhesion on the surface of zirconia. Thirty presintered zirconia specimens were divided into 6 groups of 5 after being polished with silicon carbide paper (1200 grit). A different surface treatment was applied to each group (no treatment [group Ct] and 120-μm alumina abrasion for 5, 8, 10, 12, and 15 seconds [A5s, A8s, A10s, A12s, and A15s]), and the specimens were then densely sintered. The mean centric linear roughness (Ra) was measured, and the 3D measurement of surface roughness (3D roughness) was determined. The number of colony forming units (CFUs) of Streptococcus mutans adhering to the surface was also examined. One-way ANOVA was used for data analysis (α=.05). Airborne-particle abrasion before sintering significantly increased surface roughness. Group A8s, A10s, A12s, and A15s showed statistically significant higher CFU/mL than did group A5s (P<.05). No difference was found in CFU/mL between group Ct and A5s (P=.230). Airborne-particle abrasion before sintering is a useful method of increasing the surface roughness of zirconia. Ra < 0.58 μm is necessary to inhibit the adherence of S. mutans to zirconia. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Peri-implant bone organization surrounding zirconia-microgrooved surfaces circularly polarized light and confocal laser scanning microscopy study.

    PubMed

    Delgado-Ruiz, Rafael Arcesio; Abboud, Marcus; Romanos, Georgios; Aguilar-Salvatierra, Antonio; Gomez-Moreno, Gerardo; Calvo-Guirado, Jose Luis

    2015-11-01

    To study the peri-implant bone organization pattern of immediately loaded (IL) zirconia implants with microgrooved surfaces. Forty-eight dental implants of 4 mm diameter and 10 mm length were inserted after two months postextraction healing in the edentulous mandible of six dogs. Three groups of sixteen implants were used, titanium implants (Control), zirconia implants (test A), and zirconia-microgrooved implants (test B), which were loaded immediately. After 4-month healing period, implant-bone samples were processed and analyzed by circularly polarized light (CPL) and confocal laser scanning microscopy (CLSM) in two regions of interest ROI1 (to evaluate the interthread bone) and ROI2 (to evaluate the bone adjacent to the threads) of 1 mm thickness × 10 mm length each one. Bone organization differs near to the test B, compared with test A and control surfaces, active remodeling was detected surrounding test B implants, with alternancy of organized zones, meanwhile controls and test A areas showed organized areas mainly at 2 mm of implant surfaces. Transverse collagen fibers were significatively higher at ROI1 for test B implants (60.34 ± 4.34%), compared with controls (47.25 ± 3.51%) and test A (43.78 ± 2.78%) groups (P < 0.05). Meanwhile, it was not found any significant difference between groups in ROI2 (P > 0.05). CLSM confirmed the presence of collagen mineralized matrix inside microgrooves of test B groups. 3D reconstruction showed blood vessels in direct contact with the implant surfaces of all groups and bone and blood vessels penetration inside the microgrooves in test B group. The organized pattern of the microgrooved surfaces is able to induce transverse collagen fiber microenvironment reaction to the load, being positive to promote and to maintain the bone remodeling; in addition blood vessels and bone cells are able to penetrate microgrooved surfaces. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Surface Characterization and Short-term Adhesion to Zirconia after Ultra-short Pulsed Laser Irradiation.

    PubMed

    Esteves-Oliveira, Marcella; Jansen, Patrick; Wehner, Martin; Dohrn, Andreas; Bello-Silva, Marina Stella; Eduardo, Carlos de Paula; Meyer-Lueckel, Hendrik

    To evaluate the suitability of an ultra-short pulsed laser (USPL) to treat zirconia ceramic surfaces and increase their adhesion to dual-curing resin cement. Twenty 10 × 10 × 5 mm³ blocks were prepared from a zirconia ceramic (Y-TZP). The specimens were polished and randomly assigned to four groups (n = 5) which received the following surface treatments: sandblasting (SB) with Al₂O₃ particles and silica coating (SC) with SiO₂ particles as positive controls; two groups received USPL irradiation, one with 10 scan repetitions (L10) and the other with 20 (L20). Laser irradiation was performed at 1030 nm, 2.3 J/cm², 6 ps pulse duration. The ceramic blocks were duplicated in composite resin and cemented with a dual-curing resin cement. Half of the blocks were then stored in water (37°C) for 24 h and the other half for 1 month. At each time, 40 to 60 sticks per group were subjected to microtensile bond strength testing. Data were analyzed statistically using the Kruskal-Wallis test (α = 0.05). Laser-treated zirconia presented statistically significantly higher roughness than did SB and SC. After 24 h, the highest bond strength means (MPa) were achieved by L10 (42.3 ± 10.8) and L20 (37.9 ± 14.4), and both of them were statistically significantly higher than SB (22.0 ± 5.3) and SC (20.8 ± 7.1) (p < 0.05). After 1 month of storage, L10- and L20-treated zirconia still showed significantly higher bond strengths than did SB- and SC-treated zirconia (p < 0.05). USPL irradiation significantly increases bond strength of zirconia ceramic to dual-curing resin cement and might be an alternative for improving adhesion to this material.

  6. SEM observation and wettability of variously processed and fractured surface of dental zirconia

    NASA Astrophysics Data System (ADS)

    Tarumi, Naoyoshi; Uo, Motohiro; Yamaga, Eiji; Watari, Fumio

    2012-12-01

    Current dental zirconia has several problems in clinical application such as chipping, fracture and detachment. To reduce these problems the surface after various treatments was analyzed by SEM observation, contact angle measurement and surface roughness measurement, and compared. The surface after mirror polishing was smooth. Porcelain layering was smooth except large formed grooves by bubbles. After sandblast and tribochemical treatments, the surfaces showed several micron-sized caving with micron to submicron-level irregularities. Sandblast and tribochemical treatments with the lager roughness had the smaller water contact angle than silicone wheel polishing. Clinically fractured surface of zirconia showed a more complex structure than manually fractured surface, which may be due to the various mode of stress to be imposed repetitively to various direction.

  7. pH control of the structure, composition, and catalytic activity of sulfated zirconia

    SciTech Connect

    Ivanov, Vladimir K.; Baranchikov, Alexander Ye.; Kopitsa, Gennady P.; Lermontov, Sergey A.; Yurkova, Lyudmila L.; Gubanova, Nadezhda N.; Ivanova, Olga S.; Lermontov, Anatoly S.; Rumyantseva, Marina N.; Vasilyeva, Larisa P.; Sharp, Melissa; Pranzas, P. Klaus; Tretyakov, Yuri D.

    2013-02-15

    We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to {approx}2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to {approx}80 m{sup 2}/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions. - Graphical abstract: Surface fractal dimension of amorphous sulfated zirconia and specific surface area and catalytic activity of crystalline sulfated zirconia as a function of precipitation pH. Highlights: Black-Right-Pointing-Pointer Structural transformation of amorphous hydrous zirconia into sulfated zirconia is studied. Black-Right-Pointing-Pointer Precipitation pH controls surface fractal dimension of amorphous zirconia gels. Black-Right-Pointing-Pointer Precipitation pH is the key factor governing properties of sulfated zirconia.

  8. Effect of liner and porcelain application on zirconia surface structure and composition

    PubMed Central

    Alghazzawi, Tariq F; Janowski, Gregg M

    2016-01-01

    The purpose of this study was to determine if there is an effect of liner and porcelain application (layering and pressing techniques) on the surface of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), which were exposed to permutations of liner, layered porcelain, and pressed porcelain. Scanning electron microscope (SEM)/energy dispersive spectroscope (EDS) was used to identify changes in composition and microstructure after removing liner and porcelain with hydrofluoric acid. Simulated aging was also conducted to determine the effect of liner and porcelain on low-temperature degradation. The control group had a typical equiaxed grain structure, referred to as unaffected. When covered with liner or porcelain, some areas changed in structure and composition and were termed affected. The frequency of affected structure decreased when liner was covered with either layered porcelain or pressed porcelain. There were statistical differences (P<0.05) in the composition between affected and unaffected for zirconium (layered porcelain with liner: affected=60% (0.8%) (m/m), unaffected=69% (4%), layered porcelain without liner: affected=59% (3%), unaffected=65% (3%)) and oxygen (layered porcelain with liner: affected=35% (2%), unaffected=26% (4%), layered porcelain without liner: affected=35% (3%), unaffected=30% (2%)). However, there were statistical differences (P<0.05) in the composition for zirconium and oxygen of the aged layered porcelain without liner only. The liner should not be used before porcelain application, especially when using the layering technique for zirconia restorations. Furthermore, pressing should be considered the technique of choice over layering. PMID:27445089

  9. Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro.

    PubMed

    Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

    2013-12-04

    Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO₂) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO₂ coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential.

  10. Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro

    PubMed Central

    Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J.; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

    2013-01-01

    Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO2) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential. PMID:28788415

  11. Zirconia Implants in Esthetic Areas: 4-Year Follow-Up Evaluation Study

    PubMed Central

    Borgonovo, Andrea Enrico; Censi, Rachele; Vavassori, Virna; Arnaboldi, Oscar; Maiorana, Carlo

    2015-01-01

    Objectives. The aim is to evaluate the survival and success rates, as well as the marginal bone loss (MBL) and periodontal indexes of zirconia implants positioned in the esthetic jaw areas. Materials and Method. 13 patients were selected and 20 one-piece zirconia implants were used for the rehabilitation of single tooth or partially edentulous ridge in the esthetic jaw areas. Six months after surgery and then once a year, a clinical-radiographic evaluation was performed in order to estimate peri-implant tissue health and marginal bone loss. Results. The survival and success rates were 100%. The average marginal bone loss from baseline to 48 months after surgery was +2.1 mm. Four years after surgery, the median and the mode for visible Plaque Index and Bleeding On Probing resulted 1 whereas Probing Pocket Depth amounted to 3 mm (SD = ±0.49 mm). Conclusion. One-piece zirconia dental implants are characterized by high biocompatibility, low plaque adhesion, and absence of microgap that can be related to the clinical success of these implants even in the esthetic areas. PMID:26124836

  12. Effects of Different Lasers and Particle Abrasion on Surface Characteristics of Zirconia Ceramics

    PubMed Central

    Arami, Sakineh; Tabatabae, Masoume Hasani; Namdar, Seyedeh Fatemeh; Chiniforush, Nasim

    2014-01-01

    Objective: The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP) after surface treatment with lasers and airborne-particle abrasion. Materials and Methods: First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7) and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ) and no treatment (controls). Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM. Results: According to ANOVA and Tukey’s test, the mean surface roughness (Ra) after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers. Conclusion: Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic. PMID:24910700

  13. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    PubMed

    Arami, Sakineh; Tabatabae, Masoume Hasani; Namdar, Seyedeh Fatemeh; Chiniforush, Nasim

    2014-03-01

    The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP) after surface treatment with lasers and airborne-particle abrasion. First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7) and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ) and no treatment (controls). Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM. According to ANOVA and Tukey's test, the mean surface roughness (Ra) after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers. Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  14. Bond strength of resin cement to zirconia ceramic with different surface treatments.

    PubMed

    Usumez, Aslıhan; Hamdemirci, Nermin; Koroglu, Bilge Yuksel; Simsek, Irfan; Parlar, Ozge; Sari, Tugrul

    2013-01-01

    Zirconia-based ceramics offer strong restorations in dentistry, but the adhesive bond strength of resin cements to such ceramics is not optimal. This study evaluated the influence of surface treatments on the bond strength of resin cement to yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic. Seventy-five plates of Y-TZP ceramic were randomly assigned to five groups (n = 15) according to the surface treatments [airborne particle abrasion, neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation (Fidelis Plus 3, Fotona; 2 W, 200 mJ, 10 Hz, with two different pulse durations 180 or 320 μs), glaze applied, and then 9.5 % hydrofluoric acid gel conditioned, control]. One specimen from each group was randomly selected, and specimens were evaluated with x-ray diffraction and SEM analysis. The resin cement (Clearfil Esthetic Cement, Kuraray) was adhered onto the zirconia surfaces with its corresponding adhesive components. Shear bond strength of each sample was measured using a universal testing machine at a crosshead speed of 1 mm/min. Bond strengths were analyzed through one-way ANOVA/Tukey tests. Surface treatments significantly modified the topography of the Y-TZP ceramic. The Nd:YAG laser-irradiated specimens resulted in both increased surface roughness and bond strength of the resin cement. The highest surface roughness and bond strength values were achieved with short pulse duration. Nd:YAG laser irradiation increased both surface roughness of Y-TZP surfaces and bond strength of resin cement to the zirconia surface.

  15. A novel etching technique for surface treatment of zirconia ceramics to improve adhesion of resin-based luting cements

    PubMed Central

    Ruyter, Eystein Ivar; Vajeeston, Nalini; Knarvang, Torbjørn; Kvam, Ketil

    2017-01-01

    Abstract Objectives: Bonding of zirconia crowns and bridges to abutments is important, not only bonding of the thin resin layer to the abutment, but also bonding to the zirconia ceramic is crucial. Both mechanical and chemical adhesion are desired. Mechanical retention of dental porcelain achieved by etching with moderately concentrated hydrofluoric acid is not possible with zirconia ceramics. The purpose of this study was to show that etching is possible with relative low melting fluoride compounds such as ammonium hydrogen difluoride and potassium hydrogen difluoride. Materials and methods: Before melting, the fluorides can be introduced as powders or as aqueous slurries to the contact surfaces of the zirconia. After melting, the yttria-stabilized zirconia surface revealed a surface similar to an HF-etched dental feldspathic porcelain surface. Shear bond testing (n = 10) was performed with zirconia attached to zirconia with the Duo-Link composite luting cement (Bisco) after treatment of the etched zirconia surfaces with Bis-Silane (Bisco) and the Porcelain Bonding Resin (Bisco). Results: Values for adhesive strength (mean ± standard deviation) after melt etching of the surfaces with initially dry powders were for K[FHF], (31.2 ± 7.5) MPa and for NH4[FHF] (31.0 ± 11.8) MPa. When initially aqueous slurries were applied, the values were for K[FHF] (42.7 ± 12.7) MPa and for NH4[FHF] (40.3 ± 10.0) MPa. Conclusion: Good adhesion to zirconia can be achieved by a procedure including etching with selected melted fluoride compounds. PMID:28642930

  16. Effect of mechanochemical surface preparation on bonding to zirconia of a tri-n-butylborane initiated resin.

    PubMed

    Akazawa, Nobutaka; Koizumi, Hiroyasu; Nogawa, Hiroshi; Nakayama, Daisuke; Kodaira, Akihisa; Matsumura, Hideo

    2017-01-31

    This study aimed to evaluate the effect of surface preparation on bond strength of a tri-n-butylborane initiated resin (MMA-TBB) bonded to zirconia. Zirconia disks were either airborne-particle abraded with alumina or silica-coated. The disks were thereafter primed with one of the following materials: phosphate-silane (Clearfil Ceramic Primer), phosphate (Alloy Primer), or silane (ESPE Sil). The specimens were bonded with the MMA-TBB. Shear bond strength was determined both before and after thermocycling. Bond strength of unprimed zirconia (control) was not affected by the surface roughness of each adherend. Priming with phosphate was effective for bonding alumina-blasted zirconia. Priming with silane was effective for bonding silica-coated zirconia. Priming effect of the phosphate-silane was superior to that of silane alone for bonding silica-coated zirconia. Bond strength to zirconia of the MMATBB is significantly influenced by a combination of the specific functional monomer and the surface modification performed rather than the material surface roughness.

  17. Shear bond strength in zirconia veneered ceramics using two different surface treatments prior veneering.

    PubMed

    Gasparić, Lana Bergman; Schauperl, Zdravko; Mehulić, Ketij

    2013-03-01

    Aim of the study was to assess the effect of different surface treatments on the shear bond strength (SBS) of the veneering ceramics to zirconia core. In a shear test the influence of grinding and sandblasting of the zirconia surface on bonding were assessed. Statistical analysis was performed using SPSS statistical package (version 17.0, SPSS Inc., Chicago, IL, USA) and Microsoft Office Excel 2003 (Microsoft, Seattle, WA, USA). There was a significant difference between the groups considering shear bond strength (SBS) values, i.e. ground and sandblasted samples had significantly higher SBS values than only ground samples (mean difference = -190.67; df = 10, t = -6.386, p < 0.001). The results of the present study indicate that ground and sandblasted cores are superior to ground cores, allowing significantly higher surface roughness and significantly higher shear bond strength between the core and the veneering material.

  18. A comparative study of the surface structure, acidity, and catalytic performance of tungstated zirconia prepared from crystalline zirconia or amorphous zirconium oxyhydroxide.

    PubMed

    Lebarbier, Vanessa; Clet, Guillaume; Houalla, Marwan

    2006-07-20

    Tungstated zirconias prepared from W deposition on zirconium oxyhydroxide are reportedly active for alkane isomerization, whereas solids synthesized by impregnation of zirconia are inactive. The origin of the differences between the two preparations is not fully understood. The present paper examines the influence of W surface density and the nature of the support on the surface structure, development of the acidity, and catalytic performance of WO(x)()/ ZrO(2) catalysts. Two series of catalysts containing W surface densities up to 5.2 at. W/nm(2) were prepared by pore volume impregnation of two different supports: zirconium oxyhydroxide and predominantly tetragonal zirconia (65% tetragonal, 35% monoclinic). The texture and structure of the catalysts were investigated by BET measurements, X-ray diffraction, Raman and infrared spectroscopy. The catalytic activity was tested for 2-propanol dehydration and n-hexane isomerization. For catalysts obtained by impregnation of Zr oxyhydroxide, Raman results showed that W was present as a surface phase. Infrared spectra indicated an increase in the degree of polymerization of W species with increasing W surface density. The development of the acidity was monitored by lutidine adsorption and desorption at 523 K, followed by infrared spectroscopy. The results indicated the presence of a threshold of W surface density at 1.3 at. W/ nm(2) for the detection of these acid sites, followed by a progressive increase in their abundance with increasing W surface density. The development of Brønsted acidity correlated with the evolution of the infrared bands attributed to "extensively" polymerized W species. A direct relationship was observed between the abundance of Brønsted acid sites and the catalytic activity for 2-propanol dehydration. For n-hexane isomerization, compared to 2-propanol dehydration, a higher threshold of W surface densities (3.4 at. W/ nm(2)) for the development of activity was observed. The difference was

  19. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    SciTech Connect

    Liaw, B.Y.; Song, S.Y.

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  20. An in vitro comparison of shear bond strength of zirconia to enamel using different surface treatments.

    PubMed

    Zandparsa, Roya; Talua, Nayrouz A; Finkelman, Matthew D; Schaus, Scott E

    2014-02-01

    The purpose of this in vitro study was to compare the shear bond strength of an airborne-particle abraded zirconia, an acid-etched zirconia (Piranha solution), an Alloy Primer treated zirconia, and a silaned zirconia to enamel, all bonded with a phosphate-methacrylate resin luting agent. Seventy extracted intact human molars were collected, cleaned, and mounted in autopolymerizing acrylic resin, with the experimental surface of the teeth exposed. The specimens were randomly divided into seven groups of zirconia specimens (4 mm diameter, 2 mm thick). Group 1: Airborne-particle abrasion; group 2: Airborne-particle abrasion and Z-PRIME Plus; group 3: Airborne-particle abrasion and alloy primer; group 4: Piranha solution 7:1; group 5: Piranha solution 7:1 and Z-PRIME Plus; group 6: Piranha solution 7:1 and Alloy primer; group 7: CoJet and silane. All specimens were luted with a phosphate-methacrylate resin luting agent (Panavia F2.0) and stored in distilled water for 1 day, then thermocycled (5°C and 55°C) for 500 cycles and tested for shear bond strength (SBS), measured in MPa, with a universal testing machine at a 0.55 mm/min crosshead speed. All specimens were inspected under a scanning electron microscope to determine mode of failure. The mean values and standard deviations of all specimens were calculated for each group. A one-way ANOVA was performed, and multiple pairwise comparisons were then completed with post hoc Tukey test (alpha = 0.05). The airborne-particle abrasion and Z-PRIME Plus group resulted in a significantly higher SBS than the other groups (21.11 ± 6.32 MPa) (p < 0.001). The CoJet and silane group (15.99 ± 8.92 MPa) and airborne-particle abrasion and alloy primer group (11.07 ± 4.34 MPa) showed high shear bond strength but not statistically significant from the airborne-particle abrasion group (14.23 ± 5.68 MPa). Failure mode was predominately mixed in groups 1, 2, 3, and 7 with islands of retained resin on the zirconia and enamel surfaces

  1. Effect of Surface Treatment with Carbon Dioxide (CO2) Laser on Bond Strength between Cement Resin and Zirconia

    PubMed Central

    Kasraei, Shahin; Atefat, Mohammad; Beheshti, Maryam; Safavi, Nassimeh; Mojtahedi, Maryam; Rezaei-Soufi, Loghman

    2014-01-01

    Introduction: Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques, laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of Carbon Dioxide (CO2) Laser treatment on shear bond strength (SBS) of resin cement to zirconia ceramic. Methods: In this in vitro study thirty discs of zirconia with a diameter of 6 mm and a thickness of 2 mm were randomly divided into two groups of 15. In the test group the zirconia disc surfaces were irradiated by CO2 laser with an output power of 3 W and energy density of 265.39 j/cm2. Composite resin discs were fabricated by plastic molds, measuring 3 mm in diameter and 2 mm in thickness and were cemented on zirconia disk surfaces with Panavia F2.0 resin cement (Kuraray Co. Ltd, Osaka, Japan). Shear bond strength was measured by a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture type was assessed under a stereomicroscope at ×40. Surface morphologies of two specimens of the test group were evaluated under SEM before and after laser pretreatment. Data was analyzed by paired t-test (p value < 0.05). Results: The mean SBS values of the laser and control groups were 12.12 ± 3.02 and 5.97 ± 1.14 MPa, respectively. Surface treatment with CO2 laser significantly increased SBS between resin cement and zirconia ceramic (p value = 0.001). Conclusion: Under the limitations of this study, surface treatment with CO2 laser increased the SBS between resin cement and the zirconia ceramic. PMID:25653809

  2. Effect of surface treatments of zirconia ceramics on the bond strength to resin cement.

    PubMed

    Cheung, Guy C; Botelho, Michael G; Matinlinna, Jukka P

    2014-02-01

    The purpose of this in vitro study was to evaluate the bond strength of a resin luting cement to zirconia surfaces that had received two novel surface pretreatment methods: etching of a pre-fired overglaze or paste liner on the zirconia substrate. Fully sintered zirconia disks were assigned to 6 groups according to the surface pretreatment: firing of 2 layers of paste liner which was then etched with hydrofluoric acid and treated with silane (Liner group); firing of 2 layers of overglaze which were then etched with hydrofluoric acid and treated with silane (glaze group); Rocatec treatment and silane application (Rocatec group); Rocatec treatment followed by ultrasonic cleaning and silanization (ultrasonic-Rocatec group); sandblasted with alumina (alumina group); as-sintered with no pretreatment (control group). Twenty composite resin cylinders were bonded to each group with Panavia F 2.0. Each group was further divided into 2 subgroups (n = 10) for 2 different storage conditions: 24 h water storage or 3 weeks water storage plus 6000 thermocycles between 5°C and 55°C. The shear bond strength was then determined. Statistical analyses with two-way ANOVA were conducted; the level of significance was set at p < 0.05. At 24 h, the shear bond strength values of all groups except the control showed no statistically significant difference. After artificial aging, the mean bond strength of all groups dropped, but the decrease in the glaze group was not statistically significant. The glaze group showed the highest shear bond strength. However, that was not statistically different from the liner or the Rocatec group without ultrasonic cleaning (p < 0.05). All the control specimens debonded spontaneously after aging. Ultrasonic cleaning after Rocatec treatment caused a reduction in shear bond strength, but the difference was not statistically significant. Both the fired paste liner and overglazed ceramic treated zirconia surfaces provided a strong and durable bond to resin

  3. Shear bond strength of veneering ceramic to zirconia core after different surface treatments.

    PubMed

    Kirmali, Omer; Akin, Hakan; Ozdemir, Ali Kemal

    2013-06-01

    The aim of this study was to evaluate the effect of different surface treatments: sandblasting, liners, and different laser irradiations on shear bond strength (SBS) of pre-sintered zirconia to veneer ceramic. The SBS between veneering porcelain and zirconium oxide (ZrO2) substructure was weak. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to veneering porcelain. There is no study that evaluated the bond strength between veneering porcelain and the different surface treatments on pre-sintered ZrO2 substructure. Two hundred specimens with 7 mm diameter and 3 mm height pre-sintered zirconia blocks were fabricated. Specimens were randomly divided into 10 groups (n=20) according to surface treatments applied. Group C, untreated (Control); Group E, erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiated; Group N, neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiated; Group SB, sandblasted; Group L, liner applied; Group NL, Nd:YAG laser irradiated+liner applied; Group EL, Er:YAG laser irradiated+liner applied; Group SN, sandblasted+Nd:YAG laser irradiated; Group SE, sandblasted+Er:YAG laser irradiated; and Group SL, sandblasted+liner applied. The disks were then veneered with veneering porcelain. Before the experiment, specimens were steeped in 37°C distilled water for 24 h. All specimens were thermocycled for 5000 cycles between 5°C and 55°C with a 30 sec dwell time. Shear bond strength test was performed at a crosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Surface treatments significantly changing the topography of the yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic according to scanning electron microscopic (SEM) images. The highest mean bond strength value was obtained in Group SE, and the lowest bond strength value was observed in NL group. Bond strength values of the other groups were similar to each other. This

  4. A DFT study of Ni clusters deposition on titania and zirconia (101) surfaces

    NASA Astrophysics Data System (ADS)

    Tosoni, Sergio; Chen, Hsin-Yi Tiffany; Pacchioni, Gianfranco

    2016-04-01

    Density functional calculations are employed to simulate the deposition of an isolated Ni atom and a Ni10 particle on the stoichiometric and reduced anatase TiO2 (101) and tetragonal ZrO2 (101) surfaces. The main purpose of this work is to study the modification of the electronic structure of the oxide induced by the metal, aiming at the understanding of the physical properties of new catalysts for biomass conversion. When the adsorption of a Ni atom takes place on stoichiometric surfaces, no major charge transfer is observed. On reduced titania, and more pronouncedly on reduced zirconia, the Ni atom is negatively charged, provided that the vacancy is in direct contact with the adsorbed metal atom. For Ni10, on titania the bonding is dominated by the hybridization of the metal and the oxide states but we did not find evidence for a direct reduction of the oxide via formation of Ti3 + states. For Ni10 on zirconia, the metal particle is positively charged on the stoichiometric surface and negatively charged on the reduced one but, again, there is no indication of a direct reduction of the oxide. Finally, the reverse oxygen spillover is considered as a possible route to reduce the oxide support. The result is that Ni10 promotes oxygen spillover on titania almost spontaneously, while on zirconia this process is thermodynamically unfavourable.

  5. Effect of different laser surface treatment on microshear bond strength between zirconia ceramic and resin cement.

    PubMed

    Akhavan Zanjani, Vagharaldin; Ahmadi, Hadi; Nateghifard, Afshin; Ghasemi, Amir; Torabzadeh, Hassan; Abdoh Tabrizi, Maryam; Alikhani, Farnaz; Razi, Reza; Nateghifard, Ardalan

    2015-11-01

    The purpose of this study was to evaluate the effect of sandblasting, carbon dioxide (CO₂), and erbium,chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers on the microshear bond strength of zirconia to resin cement. Sixty-one sintered yttria stabilized tetragonal zirconia blocks (10 × 5 × 2 mm) were prepared and divided into four experimental groups (n = 15); one sample was retained as a control. The samples were treated by aluminium oxide air abrasion, CO₂4W, Er,Cr:YSGG 3W, and Er,Cr:YSGG 2W, respectively. One sample from each group and the control sample were analyzed by scanning electron microscope. Panavia F2.0 resin microcylinders were prepared and placed on treated surfaces, light cured, and incubated for 48 h. Microshear bond strength testing was done by a microtensile tester machine, and the type of bond failures were determined by stereomicroscope. Data were analyzed by one-way anova and Tukey's test at a significance level of P < 0.05. Air abrasion showed the highest microshear bond strength (P < 0.05) among all groups. CO₂and Er,Cr:YSGG 3W laser showed significantly higher bond strength than Er,Cr:YSGG 2W (P < 0.05). Apparent micromechanical roughening and irregularities were seen in the air abrasion-treated samples, and the bond failure was mostly mixed type. In the laser-treated surfaces, the roughness was much less than the air abrasion-treated surfaces, and the mode of failure was almost pure adhesive. Air abrasion has a greater effect than CO₂and Er,Cr:YSGG lasers in the treatment of zirconia ceramic surfaces to enhance the bonding strength of resin cement to zirconia. CO₂laser at 4W and Er,Cr:YSGG laser at only 3-W output power can be regarded as surface treatment options for roughening the zirconia surface to establish better bond strength with resin cements. © 2014 Wiley Publishing Asia Pty Ltd.

  6. Mechanical properties of zirconia after different surface treatments and repeated firings

    PubMed Central

    Demir, Necla; Kara, Özlem; Ozturk, A. Nilgun; Özel, Faruk

    2014-01-01

    PURPOSE This study investigated the influence of surface conditioning procedures and repeated firings on monoclinic content and strength of zirconia before cementation. MATERIALS AND METHODS Sintered bar-shaped zirconia specimens were subjected to no surface treatment (control), air abrasion, or grinding (n=21). Their roughness was evaluated using a profilometer, and microscope analysis was performed on one specimen of each group. Then, 2 or 10 repeated firings (n=10) were executed, the monoclinic content of specimens was analyzed by X-ray diffraction, and a three-point flexural strength test was performed. Surface roughness values were compared using one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests, the monoclinic content values were tested using Kruskal-Wallis and Mann-Whitney U tests, and the flexural strength values were tested using two-way ANOVA and Tukey HSD tests (P=.05). Spearman's correlation test was performed to define relationships among measured parameters. RESULTS Surface-treated specimens were rougher than untreated specimens and had a higher monoclinic content (P<.005), and the relationship between roughness and monoclinic content was significant (P<.000). Neither surface treatment nor firing significantly affected the flexural strength, but Weibull analysis showed that for the air-abraded samples the characteristic strength was significantly lower after the 10th firing than after the 2nd firing. CONCLUSION After firing, a negligible amount of monoclinic content remained on the zirconia surfaces, and rougher surfaces had higher monoclinic contents than untreated surfaces. Multiple firings could be performed if necessary, but the fracture probability could increase after multiple firings for rougher surfaces. PMID:25551006

  7. Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

    PubMed

    Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei

    2015-02-01

    This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

  8. Influence of Heat Treatment and Veneering on the Storage Modulus and Surface of Zirconia Ceramic

    PubMed Central

    Siavikis, Georgius; Behr, Michael; van der Zel, Jef M; Feilzer, Albert J; Rosentritt, Martin

    2011-01-01

    Objectives: Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of zirconia. Methods: Zirconia bars (Cercon, DeguDent, G; 0.5x2x20 mm) were fabricated and treated according to veneering conditions. Besides heating regimes between 680°C and 1000°C (liner bake and annealing), sandblasting (Al2O3) or steam cleaning were used. The bars were investigated after 90 days storage in water and acid. For investigating the influence of veneering, the bars were veneered in press- or layer technique. Dynamic mechanical analysis (DMA) in a three-point-bending design was performed to determine the storage modulus between 25°C and 200°C at a frequency of 1.66 Hz. All specimens were loaded on top and bottom (treatment on pressure or tensile stress side). Scanning electron microscopy (SEM) was used for evaluating the superficial changes of the zirconia surface due to treatment. Statistical analysis was performed using Mann Whitney U-test (α=0.05). Results: Sintered zirconia provided a storage modulus E’ of 215 (203/219) GPa and tan δ of 0.04 at 110°C. A 10%-decrease of E’ was found up to 180°C. The superficial appearance changed due to heating regime. Sandblasting reduced E’ to 213 GPa, heating influenced E’ between 205 GPa (liner bake 1) and 222 GPa (dentin bake 1). Steam cleaning, annealing and storage changed E’ between 4 GPa and 22 GPa, depending on the side of loading. After veneering, strong E’-reduction was found down to 84 GPa and 125 GPa. Conclusions: Veneering of zirconia with glass-ceramic in contrast to heat treating during veneering procedure had a strong influence on the modulus. The application of the glass-ceramic caused a stronger decrease of the storage modulus. PMID:21494388

  9. Methacrylate bonding to zirconia by in situ silica nanoparticle surface deposition.

    PubMed

    Oliveira-Ogliari, Aline; Collares, Fabrício M; Feitosa, Victor P; Sauro, Salvatore; Ogliari, Fabrício A; Moraes, Rafael R

    2015-01-01

    This study introduces an innovative method to enhance adhesion of methacrylate-based cements to yttria-stabilized zirconia (Y-TZP) by means of a silica-nanoparticle deposition process. Two alkoxide organic precursors, tetraethyl-orthosilicate (TEOS) and zirconium tert-butoxide (ZTB) were diluted in hexane at different concentrations in order to obtain several experimental materials to enhance deposition of a SiO(x) reactive layer to Y-TZP. This deposition was attained via sintering alkoxide precursors directly on pre-sintered zirconia (infiltration method—INF) or application on the surface of fully sintered zirconia (coating method—COA). Untreated specimens and a commercial tribochemical silica coating were also tested as controls and all the treated Y-TZP specimens were analyzed using SEM-EDX. Specimens were bonded using silane, adhesive and dual-cure luting cement and submitted to shear bond strength test after different water storage periods (24 h, 3-, 6- and 12-months). SEM-EDX revealed Y-TZP surface covered by silica nanoclusters. The morphology of silica-covered Y-TZP surfaces was influenced by sintering method, employed to deposit nanoclusters. High bond strength (MPa) was observed when using COA method; highest TEOS percentage achieved the greatest bond strengths to Y-TZP surface (36.7±6.3 at 24 h). However, bonds stability was dependent on ZTB presence (32.9±9.7 at 3 months; 32.3±7.1 at 6 months). Regarding INF method, the highest and more stable resin-zirconia bond strength was attained when using experimental solutions containing TEOS and no ZTB. Both sintering methods tested in this study were able to achieve a bonding performance similar to that of classic tribochemical strategies. This study demonstrates that it is possible to achieve a reliable and long-lasting bonding between yttria-stabilized zirconia ceramic and methacrylate-based cements when using this novel, simple, and cost-effective bonding approach. Copyright © 2014 Academy of Dental

  10. Influence of surface treatment on the resin-bonding of zirconia.

    PubMed

    Şanlı, Seda; Çömlekoğlu, Mine Dündar; Çömlekoğlu, Erhan; Sonugelen, Mehmet; Pamir, Tijen; Darvell, B W

    2015-06-01

    To compare the effect of various surface treatments on the bonding of luting resin cements to zirconia under four-point bending. Bar specimens (n = 200) (2 mm × 5 mm × 25 mm) were prepared from zirconia blocks (VITA In-Ceram YZ, Vita Zahnfabrik) with the cementation surface (2 mm × 5 mm) of groups of 40 treated in one of five ways: airborne particle abrasion with 50μm Al2O3 (GB), zirconia primer (Z-Prime Plus, Bisco) (Z), glaze ceramic (Crystall.Glaze spray, Ivoclar Vivadent) + hydrofluoric acid (GHF), fusion glass-ceramic (Crystall.Connect, Ivoclar Vivadent) (CC), or left untreated as control (C). Within each treatment, bars were cleaned ultrasonically for 15 min in ethanol and then deionized water before bonding in pairs with one of two luting resins: Panavia F 2.0, (Kuraray) (P); RelyX U-200 (3M/Espe) (R), to form 10 test specimens for each treatment and lute combination. Mechanical tests were performed and bond strengths (MPa) were subject, after log transformation, to analysis of variance, Shapiro-Wilk and Holm-Sidak tests; also log-linear contingency analysis of failure mode distribution; all with α = 0.05. Fracture surfaces were examined under light and scanning electron microscopy. While the effect of surface treatment was significant (p = 1.27 × 10(-9)), there was no detected effect due to resin (p = 0.829). All treatments except CC (30.1 MPa ×/÷ 1.44)* were significantly better than the untreated control (24.8 MPa ×/÷ 1.35) (p = 3.28 × 10(-9)). While the effect of GB - which gave the highest mean strength (50.5 MPa ×/÷ 1.29) - was not distinguishable from that of GHF (39.9 MPa ×/÷ 1.29) (p = 0.082), it was significantly better than treatment with either CC or Z (33.1 MPa ×/÷ 1.48) (p < 0.05). (* After log transformation for analysis and back; asymmetric error bounds as s.d. in log values.) The novel test method design, which has good discriminatory power, confirmed the value of gritblasting as a simple and effective treatment with low

  11. Improving adhesion between luting cement and zirconia-based ceramic with an alternative surface treatment.

    PubMed

    Martins, Aurealice Rosa Maria; Gotti, Valéria Bisinoto; Shimano, Marcos Massao; Borges, Gilberto Antônio; Gonçalves, Luciano de Souza

    2015-01-01

    This study evaluated the influence of an alternative surface treatment on the microshear bond strength (μsbs) of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO), glass and silane were not applied to the zirconia surface; G1, air blasted with 100μm glass beads + glaze + silane; G2, a gel containing 15% (by weight) glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight) glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight) glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC®, according to the manufacturer's recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The μsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey's test (p < 0.05) were applied to the bond strength values (in MPa). CO (15.6 ± 4.1) showed the lowest μsbs value. There were no statistical differences between the G1 (24.9 ± 7.4), G2 (24.9 ± 2.3), G3 (35.0 ± 10.3) and G4 (35.3 ± 6.0) experimental groups. Those groups submitted to surface treatments with higher concentrations of glass showed a lower frequency of adhesive failures. In conclusion, the glass application improved the interaction between the ceramic and the luting cement.

  12. Shear Bond Strength of the Repair Composite Resin to Zirconia Ceramic by Different Surface Treatment

    PubMed Central

    Arami, Sakineh; Hasani Tabatabaei, Masoumeh; Namdar, Fatemeh; Safavi, Nassimeh; Chiniforush, Nasim

    2014-01-01

    Introduction: The purpose of this study is the evaluation of the amount of surface roughness (Ra) of Zirconia Ceramic following different surface treatments as well as the assessment of its shear bond strength to composite resin. Methods: 40 sintered zirconia ceramic block samples were randomly divided in 4 groups of 10 and underwent the following surface treatments: a) Control group without treatment b) Air abrasion with Al2O3 particles (50um) c) Er:YAG laser with 2W power for 10s d) Nd:YAG laser with 1.5W power for 2min Then the mean surface roughness (Ra) was evaluated by profilometer. In the next step, Alloy primer was used on a section of 9mm2 on the samples following the manufacturer’s instructions. After that Clearfil AP-X composite resin in cylinder shape with an internal diameter and height of 3mm were cured on the sections mentioned. At the end, all samples were tested to assess the shear bond strength by the Universal Testing Machine at a speed of 0.5mm/min until fracture occurred. The mean shear bond strengths were calculated and statistically analyzed by One Way ANOVA. Results: ANOVA analysis showed that roughness (Ra) was significantly different between the groups (P≤0.05). Ra was higher in the Nd:YAG group compared to the other groups (P≤0.05). The lower Ra was related to the control group. Air abrasion group showed highest amounts of shear bond strength and Nd:YAG laser group demonstrated lower amounts of shear bond strength (P≤0.05). Conclusion: Various surface treatments are differently effective on bond strength. Air abrasion is the most effective method to condition zirconia ceramic surfaces. PMID:25653817

  13. Effect of surface treatment and liner material on the adhesion between veneering ceramic and zirconia.

    PubMed

    Yoon, Hyung-In; Yeo, In-Sung; Yi, Yang-Jin; Kim, Sung-Hun; Lee, Jai-Bong; Han, Jung-Suk

    2014-12-01

    Fully sintered zirconia blocks, each with one polished surface, were treated with one of the followings: 1) no treatment, 2) airborne-particle abrasion with 50μm alumina, and 3) airborne-particle abrasion with 125μm alumina. Before veneering with glass ceramic, either liner Α or liner B were applied on the treated surfaces. All veneered blocks were subjected to shear force in a universal testing machine. For the groups with liner A, irrespective of the particle size, air abrasion on Y-TZP surfaces provided greater bond strength than polishing. Application of liner B on an abraded zirconia surface yielded no significant influence on the adhesion. In addition, specimens with liner A showed higher bond strength than those with liner B, if applied on roughened surfaces. Fractured surfaces were observed as mixed patterns in all groups. For the liner A, surface treatment was helpful in bonding with veneering ceramic, while it was ineffective for the liner B. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Influence of surface treatment on the in-vitro fracture resistance of zirconia-based all-ceramic anterior crowns.

    PubMed

    Schmitter, M; Lotze, G; Bömicke, W; Rues, S

    2015-12-01

    The purpose of this study was to assess the effect of surface treatment on the fracture resistance of zirconia-based all-ceramic anterior crowns. Sixty-four zirconia-based all-ceramic anterior crowns, veneered by use of a press-on technique, were produced. For 48 crowns intraoral adjustment was simulated (A-group), 16 crowns remained unadjusted (WA-group). The adjusted area was then treated in three ways: 1. no further surface treatment; 2. polishing, with irrigation, using polishers interspersed with diamond grit for ceramics; and 3. polishing and glaze firing. Half of the specimens were loaded until fracture in an universal testing device without artificial ageing; the other crowns underwent thermocycling and chewing simulation before ultimate-load testing. Explorative statistical analysis was performed by use of non-parametric and parametric tests. In addition, fracture-strength tests according to ISO 6872 were performed for veneer ceramic subjected to the different surface treatments. Finite element analysis was also conducted for the crowns, and surface roughness was measured. Crowns in the A-group were more sensitive to aging than crowns in the WA-group (p=0.038). Although both polishing and glaze firing slightly improved the fracture resistance of the specimens, the fracture resistance in the WA-group (initial fracture resistance (IFR): 652.0 ± 107.7N, remaining fracture resistance after aging (RFR): 560.6 ± 233.3N) was higher than the fracture resistance in the A-group (polished: IFR: 477.9 ± 108.8N, RFR: 386.0 ± 218.5N; glaze firing: IFR: 535.5 ± 128.0N, RFR: 388.6 ± 202.2N). Surface roughness without adjustment was Ra=0.1 μm; for adjustment but without further treatment it was Ra=1.4 μm; for adjustment and polishing it was Ra=0.3 μm; and for adjustment, polishing, and glazing it was Ra=0.6 μm. Stress distributions obtained by finite element analysis in combination with fracture strength tests showed that fractures most probably originated from

  15. Evaluation of surface topography of zirconia ceramic after Er:YAG laser etching.

    PubMed

    Turp, Volkan; Akgungor, Gokhan; Sen, Deniz; Tuncelli, Betul

    2014-10-01

    The aim of this study is to evaluate the effect of Erbium: yttrium-aluminum-garnet (Er:YAG) laser with different pulse lengths on the surface roughness of zirconia ceramic and airborne particle abrasion. Er:YAG laser treatment is expected to be an alternative surface treatment method for zirconia ceramics; however, the parameters and success of the application are not clear. One hundred and forty zirconia discs (diameter, 10 mm; thickness, 1.2 mm) were prepared by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer's instructions. Specimens were divided into 14 groups (n=10). One group was left as polished control, one group was air-particle abraded with Al2O3 particles. For the laser treatment groups, laser irradiation was applied at three different pulse energy levels (100, 200, and 300 mJ) and for each energy level at four different pulse lengths; 50, 100, 300, and 600 μs. Surface roughness was evaluated with an optical profilometer and specimens were evaluated with scanning electron microscopy (SEM). Data was analyzed with one way ANOVA and Tukey multiple comparison tests (α=0.05). For the 100 and 200 mJ laser etching groups, 50 and 100 μs laser duration resulted in significantly higher surface roughness compared with air-particle abrasion (p<0.05). The difference among Ra values of 300 μs, 600 μs, and air-particle abrasion groups were not statistically significant (p>0.05). For the 300 mJ laser etching groups; there was no statistically significant difference among the Ra values of 50 μs, 100 μs, 300 μs, 600 μs, and air-particle abrasion groups (p>0.05). In order to increase surface roughness and promote better bonding to resin luting agents, Er:YAG laser etching may be an alternative to air-particle abrasion for zirconia ceramics. However, high levels of pulse energy and longer pulse length may have an adverse effect on micromechanical locking properties, because of a

  16. Oxygen exchange measurements on zirconia-yttria electrolyte surfaces modified by various dopants

    SciTech Connect

    Tannhauser, D.S.; Kilner, J.A.; Steele, B.C.H.

    1983-10-01

    Yttria stabilized zirconia (YSZ) has a number of practical applications as electrolyte membrane. Current interest is focused on three main devices: oxygen monitors, high temperature fuel cells, and water electrolyzers. Little is known about factors which affect the interchange of oxygen between the ambient gas and the oxide surface. Surface perfection and purity, as well as crystalline orientation, may all play a role. In view of the growing requirement for devices to operate at low temperatures (approx. 500 C), where the surface exchange becomes very slow, it is important to understand this process. Recent experiments have suggested that surface treatment of zirconia with CeO2 may accelerate reaction kinetics at electrodes. Another series of experiments by Verkerk et al has suggested that in the low temperature regime Bi2O3 - Er2O3 has much faster transfer rate for oxygen than YSZ. Consequently, a series of experiments have been started to investigate the effects of chemical treatments on the exchange of oxygen between the surface of YSZ single crystals and oxygen in the gas phase.

  17. Effects of two surface finishes on the color of cemented and colored anatomic-contour zirconia crowns.

    PubMed

    Lee, Wei-Fang; Feng, Sheng-Wei; Lu, Yi-Jie; Wu, Hsin-Jui; Peng, Pei-Wen

    2016-08-01

    The esthetic appearance of anatomic-contour zirconia restorations is influenced by the shade of the coloring liquid and the optical properties of the luting cements. However, few studies are available on the effects of surface-finishing methods and luting cements on colored anatomic-contour zirconia restorations. The purpose of this in vitro study was to investigate the effects of surface finishing methods on the color distribution of colored anatomic-contour zirconia crowns before and after being cemented onto abutments. Implant-supported anatomic-contour zirconia premolar crowns were fabricated and immersed in A3-coloring liquid for 30 seconds. The colored zirconia crowns were separated into 3 groups according to the method of surface treatment: no treatment (N), polishing (P), and glazing (G). The zirconia crowns without coloring liquid application served as the control group. CIELab color coordinates were obtained, and color differences (ΔE) between shaded crowns were calculated with a spectrophotometer. The color stability of the crown before and after cement application was also investigated. Before cement application, the mean color difference between groups N and P was 2.85 ΔE units, whereas the mean ΔE value between groups N and G was 3.27. Mean ΔE values with and without cement application among groups ranged from 2.75 to 3.45 ΔE units. The color appearance of the colored zirconia crowns was strongly influenced by the surface-finishing methods and luting cement application. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Bond strength of veneer ceramic and zirconia cores with different surface modifications after microwave sintering

    PubMed Central

    Saka, Muhammet

    2013-01-01

    PURPOSE To evaluate the effects of surface treatments on shear bond strength (SBS) between microwave and conventionally sintered zirconia core/veneers. MATERIALS AND METHODS 96 disc shaped Noritake Alliance zirconia specimens were fabricated using YenaDent CAM unit and were divided in 2 groups with respect to microwave or conventional methods (n=48/group). Surface roughness (Ra) evaluation was made with a profilometer on randomly selected microwave (n=10) and conventionally sintered (n=10) cores. Specimens were then assessed into 4 subgroups according to surface treatments applied (n=12/group). Groups for microwave (M) and conventionally (C) sintered core specimens were as follows; MC,CC: untreated (control group), M1,C1:Al2O3 sandblasting, M2,C2:liner, M3,C3:Al2O3 sandblasting followed by liner. Veneer ceramic was fired on zirconia cores and specimens were thermocycled (6000 cycles between 5°-55℃). All specimens were subjected to SBS test using a universal testing machine at 0.5 mm/min, failure were evaluated under an optical microscope. Data were statistically analyzed using Shapiro Wilk, Levene, Post-hoc Tukey HSD and Student's t tests, Two-Way-Variance-Analysis and One-Way-Variance-Analysis (α=.05). RESULTS Conventionally sintered specimens (1.06 ± 0.32 µm) showed rougher surfaces compared to microwave sintered ones (0.76 ± 0.32 µm)(P=.046), however, no correlation was found between SBS and surface roughness (r=-0.109, P=.658). The statistical comparison of the shear bond strengths of C3 and C1 group (P=.015); CC and MC group (P=.004) and C3 and M3 group presented statistically higher (P=.005) values. While adhesive failure was not seen in any of the groups, cohesive and combined patterns were seen in all groups. CONCLUSION Based on the results of this in-vitro study, Al2O3- sandblasting followed by liner application on conventionally sintered zirconia cores may be preferred to enhance bond strength. PMID:24353890

  19. Modulation of osteoblast behavior on nanopatterned yttria-stabilized zirconia surfaces.

    PubMed

    Soon, Ginny; Pingguan-Murphy, Belinda; Akbar, Sheikh Ali

    2017-04-01

    This study utilizes the technique of self-assembly to fabricate arrays of nanoislands on (001)-oriented yttria-stabilized zirconia single crystal substrates with miscut of 10° toward <110> direction. These self-assembled nanostructures were annealed at 1100°C for 5h upon doping with 10mol% gadolinium-doped ceria (GDC) by powder-suspension based method. X-Ray diffraction result showed that the miscut substrate after doping GDC was in the cubic phase. Energy dispersive X-ray (EDX) illustrates that the nanopatterned material contains all the elements from the GDC source and yttria-stabilized zirconia (YSZ) substrate. It also demonstrates a higher surface roughness and a more hydrophilic surface. The nanostructured materials were subsequently used for an in vitro study using a human fetal osteoblastic cell line (hFOB). An improved spreading, enhanced cell proliferation and up-regulated alkaline phosphatase activity (ALP) were observed on the nanopatterned substrates compared to the control substrates. Calcium deposits, which were stained positively by Alizarin Red S, appeared to be more abundant on the nanopatterned surfaces on day 7. The overall findings suggest that post fabrication treatment with surface modification such as creating a nanostructure (e.g. nanopatterns) can improve biocompatibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Polymer coating on the surface of zirconia nanoparticles by inductively coupled plasma polymerization

    SciTech Connect

    He Wei; Guo Zhigang; Pu Yikang; Yan Luting; Si Wenjie

    2004-08-09

    Polymer coating on the surface of inorganic ceramic nanoparticles is beneficial to decrease agglomeration and improve dispersion in organic solvent in ceramic injection moulding technology. A layer of thin polymer film on zirconia nanoparticles is deposited by inductively coupled ethylene/nitrogen plasma. Transmission electron microscopy photographs indicate the presence of uniform polymer coatings and the thickness of the polymer layer is estimated as several nanometers. The chemical structure of the film is revealed as quasi-polyethylene long hydrocarbon chain by x-ray photoelectron spectroscopy examination.

  1. Effect of zirconia surface treatment using nitric acid-hydrofluoric acid on the shear bond strengths of resin cements.

    PubMed

    Cho, Jin Hyung; Kim, Sun Jai; Shim, June Sung; Lee, Keun-Woo

    2017-04-01

    The aim of this study was to compare the surface roughness of zirconia when using Zircos E etching system (ZSAT), applying a nitric acid-hydrofluoric acid compound as a pretreatment agent, and also to compare the shear bonding strength according to different resin cements. ZSAT, air abrasion, and tribochemical silicacoating were applied on prepared 120 zirconia specimens (10 mm in diameter, 7 mm in height) using CAD/CAM. Each 12 specimens with 4 different resin cements (Panavia F 2.0, Rely X Unicem, Superbond C&B, and Hot bond) were applied to test interfacial bond strength. The statistical analysis was performed using SAS 9.1 (SAS Institute Inc., Cary, NC, USA). The results are as follows: after application of the ZSAT on the zirconia specimens, surface roughness value after 2-hour etching was higher than those after 1- and 3-hour etching on SEM images. For Superbond C&B and Rely X Unicem, the specimens treated with ZSAT showed higher shear bond strength values than those treated with air abrasion and tribochemical silicacoating system. Regarding the failure mode of interface over cement and zirconia surface, Rely X Unicem and Hot bond showed cohesive failures and Panavia F 2.0 and Superbond C&B showed mixed failures. Zircos E etching system in zirconia restoration could increase its shear bond strength. However, its long term success rate and clinical application should be further evaluated.

  2. Bond strength to high-crystalline content zirconia after different surface treatments.

    PubMed

    de Souza, Grace M Dias; Silva, Nelson R F A; Paulillo, Luis A M S; De Goes, Mario F; Rekow, E Dianne; Thompson, Van P

    2010-05-01

    The aim of this study was to evaluate the effect of primers, luting systems and aging on bond strength to zirconium oxide substrates. Eighteen zirconia discs (19.5 x 4 mm) were polished and treated (n = 3) either with a MDP primer (Md) or with a MDP and VBATDT primer (MV). In the control group (n = 3) no surface chemical treatment was performed. Zirconia specimens were cemented to prepolymerized composite discs utilizing resin cements - RelyX Unicem or Panavia 21 (RU and Pa, respectively). After 24 h, samples were sectioned for microtensile testing and returned to water at 37 degrees C for two different periods before being tested: 72 h or 60 days + thermocycling (5-55 degrees C/5000 cycles). Bond strength testing was performed at 1 mm/min. Values in MPa were analyzed through ANOVA and Tukey's Studentized Range (HSD) (p > 0.05). The application of MV primer resulted in the highest bond strength (22.77 MPa), statistically superior to Md primer (12.78 MPa), and control groups presented the lowest values (9.17 MPa). When luting systems were compared, RU promoted the highest bond strength (16.07 MPa) in comparison with Pa (13.75 MPa). The average bond strength decrease after aging (9.35 MPa) when compared with initial values (20.46 MPa). The results presented by this in vitro study suggest that a chemical surface treatment based on the MDP and VBATDT combination may improve bond strength between zirconia and luting system, without any previous mechanical treatment, depending on the luting system used. This chemical treatment may result in a reliable alternative to achieve adequate and durable bond strength.

  3. Effect of surface treatment on the micro-shear bond strength to zirconia

    PubMed Central

    Tashkandi, Esam

    2009-01-01

    The constant quest for finding the ultimate esthetic dental restorative material has led to numerous alternatives. These materials, in addition to possessing optical properties simulating natural teeth, should also have physical properties that can withstand the harsh oral environment. Due to their greater toughness, zirconium oxide materials have been used as a core material for all-ceramic restorations. Objective The objective of this study was to evaluate the resin-composite micro-shear bond strength to zirconia using different techniques of surface treatment. Materials and methods Fully sintered zirconia (LAVA, 3M-ESPE, Seefeld, Germany) discs were used in combination with resin-composite (Filtek Supreme, 3M-ESPE, Seefeld, Germany) discs and divided into four groups of surface treatments. The micro-shear bond strength was measured by applying an axial load on the bonded interface until failure occurred. Failure load (N) was determined and the samples were examined under a SEM and the failure type was identified. One-way analysis of variance (ANOVA) was used to analyze the data with the level of significance α = 0.05. Results Data analysis revealed significant difference between the different tested surface treatments with the group using sandblasting and coated with an experimental primer showing the highest failure load and a cohesive fracture pattern. Conclusion Within the limitations of this in vitro study the use of an experimental primer achieved a better bond strength in combination with air-abrasion particles. PMID:23960468

  4. pH control of the structure, composition, and catalytic activity of sulfated zirconia

    NASA Astrophysics Data System (ADS)

    Ivanov, Vladimir K.; Baranchikov, Alexander Ye.; Kopitsa, Gennady P.; Lermontov, Sergey A.; Yurkova, Lyudmila L.; Gubanova, Nadezhda N.; Ivanova, Olga S.; Lermontov, Anatoly S.; Rumyantseva, Marina N.; Vasilyeva, Larisa P.; Sharp, Melissa; Pranzas, P. Klaus; Tretyakov, Yuri D.

    2013-02-01

    We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to ˜2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to ˜80 m2/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions.

  5. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics: the effect of surface conditioning.

    PubMed

    Valandro, Luiz Felipe; Ozcan, Mutlu; Bottino, Marco Cícero; Bottino, Marco Antonio; Scotti, Roberto; Bona, Alvaro Della

    2006-06-01

    The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (In-Ceram Zirconia) ceramics. Ten blocks (5 x 6 x 8 mm) of In-Ceram Alumina (AL), In-Ceram Zirconia (ZR), and Procera (PR) ceramics were fabricated according to each manufacturer's instructions and duplicated in composite. The specimens were assigned to one of the two following treatment conditions: (1) airborne particle abrasion with 110-microm Al2O3 particles + silanization, (2) silica coating with 30 microm SiOx particles (CoJet, 3M ESPE) + silanization. Each ceramic block was duplicated in composite resin (W3D-Master, Wilcos, Petrópolis, RJ, Brazil) using a mold made out of silicon impression material. Composite resin layers were incrementally condensed into the mold to fill up the mold and each layer was light polymerized for 40 s. The composite blocks were bonded to the surface-conditioned ceramic blocks using a resin cement system (Panavia F, Kuraray, Okayama, Japan). One composite resin block was fabricated for each ceramic block. The ceramic-composite was stored at 37 degrees C in distilled water for 7 days prior to bond tests. The blocks were cut under water cooling to produce bar specimens (n = 30) with a bonding area of approximately 0.6 mm2. The bond strength tests were performed in a universal testing machine (crosshead speed: 1 mm/min). Bond strength values were statistically analyzed using two-way ANOVA and Tukey's test (< or = 0.05). Silica coating with silanization increased the bond strength significantly for all three high-strength ceramics (18.5 to 31.2 MPa) compared to that of airborne particle abrasion with 110-microm Al2O3 (12.7-17.3 MPa) (ANOVA, p < 0.05). PR exhibited the lowest bond strengths after both Al2O3 and silica coating (12.7 and 18.5 MPa, respectively

  6. Characterization of three commercial Y-TZP ceramics produced for their high-translucency, high-strength and high-surface area.

    PubMed

    Tong, Hui; Tanaka, Carina B; Kaizer, Marina R; Zhang, Yu

    2016-01-01

    Developing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with high strength and translucency could significantly widen the clinical indications of monolithic zirconia restorations. This study investigates the mechanical and optical properties of three Y-TZP ceramics: High-Translucency, High-Strength and High-Surface Area. The four-point bending strengths (mean ± standard error) for the three Y-TZP ceramics (n = 10) were 990 ± 39, 1416 ± 33 and 1076 ± 32 MPa for High-Translucency, High-Strength and High-Surface Area, respectively. The fracture toughness values (mean ± standard error) for the three zirconias (n = 10) were 3.24 ± 0.10, 3.63 ± 0.12 and 3.21 ± 0.14 MPa m(1/2) for High-Translucency, High-Strength and High-Surface Area, respectively. Both strength and toughness values of High-Strength zirconia were significantly higher than High-Surface Area and High-Translucency zirconias. Translucency parameter values of High-Translucency zirconia were considerably higher than High-Strength and High-Surface Area zirconias. However, all three zirconias became essentially opaque when their thickness reached 1 mm or greater. Our findings suggest that there exists a delicate balance between mechanical and optical properties of the current commercial Y-TZP ceramics.

  7. Characterization of three commercial Y-TZP ceramics produced for their high-translucency, high-strength and high-surface area

    PubMed Central

    Tong, Hui; Tanaka, Carina B.; Kaizer, Marina R.; Zhang, Yu

    2015-01-01

    Developing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with high strength and translucency could significantly widen the clinical indications of monolithic zirconia restorations. This study investigates the mechanical and optical properties of three Y-TZP ceramics: High-Translucency, High-Strength and High-Surface Area. The four-point bending strengths (mean ± standard error) for the three Y-TZP ceramics (n = 10) were 990 ± 39, 1416 ± 33 and 1076 ± 32 MPa for High-Translucency, High-Strength and High-Surface Area, respectively. The fracture toughness values (mean ± standard error) for the three zirconias (n = 10) were 3.24 ± 0.10, 3.63 ± 0.12 and 3.21 ± 0.14 MPa m1/2 for High-Translucency, High-Strength and High-Surface Area, respectively. Both strength and toughness values of High-Strength zirconia were significantly higher than High-Surface Area and High-Translucency zirconias. Translucency parameter values of High-Translucency zirconia were considerably higher than High-Strength and High-Surface Area zirconias. However, all three zirconias became essentially opaque when their thickness reached 1 mm or greater. Our findings suggest that there exists a delicate balance between mechanical and optical properties of the current commercial Y-TZP ceramics. PMID:26664123

  8. Morphology, proliferation, and gene expression of gingival fibroblasts on Laser-Lok, titanium, and zirconia surfaces.

    PubMed

    Esfahanizadeh, Nasrin; Motalebi, Sara; Daneshparvar, Niloufar; Akhoundi, Nasrin; Bonakdar, Shahin

    2016-07-01

    Soft tissue seal plays a critical role in long-term success of dental implants, and the effects of implant surface treatments such as laser ablation have been a topic of particular interest in this respect. Considering the existing controversy regarding soft tissue behavior in contact with implant surfaces, this study sought to assess the morphology, proliferation, and gene expression of human gingival fibroblasts (HGFs) on different abutment surfaces. In this in vitro, experimental study, HGFs were cultured on 45 discs (Laser-Lok, titanium, and zirconia). Cell morphology, proliferation rate, and interleukin 10 (IL-10), tumor necrosis factor alpha (TNFα), fibronectin, and integrin gene expressions were assessed by electron microscopy, methyl thiazol tetrazolium (MTT) assay, and real-time polymerase chain reaction (PCR), respectively. Data were analyzed using ANOVA and the Kruskal-Wallis H test. Fibroblast attachment was noted in all the three groups. Spindle-shaped cells with pseudopod-like processes were more frequently seen in the Laser-Lok group. Cell proliferation was significantly higher in the Laser-Lok group compared to those in the other groups (P = 0.0002). Significant differences were found in the expression of IL-10, TNFα, fibronectin, and integrin genes among the groups (P < 0.01). Within the limitations of this study, HGFs on Laser-Lok surfaces had a more mature morphology and greater proliferation and differentiation as compared to those on zirconia and titanium surfaces. This indicates better attachment of these cells to laser-modified surfaces, creating a more efficient soft tissue seal around dental implants.

  9. Catastrophic failure of a monolithic zirconia prosthesis.

    PubMed

    Chang, Jae-Seung; Ji, Woon; Choi, Chang-Hoon; Kim, Sunjai

    2015-02-01

    Recently, monolithic zirconia restorations have received attention as an alternative to zirconia veneered with feldspathic porcelain to eliminate chipping failures of veneer ceramics. In this clinical report, a patient with mandibular edentulism received 4 dental implants in the interforaminal area, and a screw-retained monolithic zirconia prosthesis was fabricated. The patient also received a maxillary complete removable dental prosthesis over 4 anterior roots. At the 18-month follow-up, all of the zirconia cylinders were seen to be fractured, and the contacting abutment surfaces had lost structural integrity. The damaged abutments were replaced with new abutments, and a new prosthesis was delivered with a computer-assisted design and computer-assisted manufacturing fabricated titanium framework with denture teeth and denture base resins. At the 6-month recall, the patient did not have any problems. Dental zirconia has excellent physical properties; however, care should be taken to prevent excessive stresses on the zirconia cylinders when a screw-retained zirconia restoration is planned as a definitive prosthesis.

  10. Surface treatment with a fractional CO2 laser enhances shear bond strength of resin cement to zirconia

    PubMed Central

    Alirezaei, Mehrnoosh

    2016-01-01

    Aims: The present study investigated the effect of different surface treatments on shear bond strength (SBS) of resin cement to zirconia. Materials and methods: Ninety zirconia blocks were prepared and divided into 6 groups of 15 by treatment. Group 1 served as the control group, whereas groups 2 and 3 were treated with air abrasion and a universal primer (Monobond plus), respectively. The remaining zirconia copings were treated with a fractional CO2 laser for 10 seconds using 10 W/10 mJ (group 4), 10 w/14 mJ (group 5) or 20 W/10 mJ (group 6). A luting cement (Clearfil SA) was bonded to the treated zirconia surfaces and cured for 40 seconds. SBS was measured with a universal testing machine and the type of bond failure was determined. Results: There was a statistically significant difference in SBS among the study groups (p<0.001). The highest SBS values were observed in the groups treated with the fractional CO2 laser at settings of 20 W/10 mJ (28.1 MPa) or 10 W/14 mJ (27.4 MPa), followed by the specimens treated with the universal primer (22.8 MPa). The control specimens exhibited the lowest SBS (9.4 MPa) among the study groups (p<0.05). There was no significant difference in the distribution of failure modes among the groups (p=0.871). Conclusions: The application of fractional CO2 laser can improve bond strength of resin cement to zirconia ceramic, and thus it could be considered as an appropriate alternative to conventional methods of zirconia surface treatment. PMID:27141151

  11. Orientation-dependent hydration structures at yttria-stabilized cubic zirconia surfaces

    DOE PAGES

    Hou, Binyang; Kim, Seunghyun; Kim, Taeho; ...

    2016-11-30

    Water interaction with surfaces is very important and plays key roles in many natural and technological processes. Because the experimental challenges that arise when studying the interaction water with specific crystalline surfaces, most studies on metal oxides have focused on powder samples, which averaged the interaction over different crystalline surfaces. As a result, studies on the crystal orientation-dependent interaction of water with metal oxides are rarely available in the literature. In this work, water adsorption at 8 mol % yttria-stabilized cubic single crystal zirconia (100) and (111) surfaces was studied in terms of interfacial hydration structures using high resolution X-raymore » reflectivity measurements. The interfacial electron density profiles derived from the structure factor analysis of the measured data show the existence of multiple layers of adsorbed water with additional peculiar metal adsorption near the oxide surfaces.Surface relaxation, depletion, and interaction between the adsorbed layers and bulk water are found to vary greatly between the two surfaces and are also different when compared to the previously studied (110) surface. The fractional ratio between chemisorbed and physisorbed water species were also quantitatively estimated, which turned out to vary dramatically from surface to surface. Finally, the result gives us a unique opportunity to reconsider the simplified 2:1 relation between chemisorption and physisorption, originally proposed by Morimoto et al. based on the adsorption isotherms of water on powder metal oxide samples.« less

  12. Orientation-dependent hydration structures at yttria-stabilized cubic zirconia surfaces

    SciTech Connect

    Hou, Binyang; Kim, Seunghyun; Kim, Taeho; Park, Changyong; Bahn, Chi Bum; Kim, Jongjin; Hong, Seungbum; Lee, Su Yong; Kim, Ji Hyun

    2016-11-30

    Water interaction with surfaces is very important and plays key roles in many natural and technological processes. Because the experimental challenges that arise when studying the interaction water with specific crystalline surfaces, most studies on metal oxides have focused on powder samples, which averaged the interaction over different crystalline surfaces. As a result, studies on the crystal orientation-dependent interaction of water with metal oxides are rarely available in the literature. In this work, water adsorption at 8 mol % yttria-stabilized cubic single crystal zirconia (100) and (111) surfaces was studied in terms of interfacial hydration structures using high resolution X-ray reflectivity measurements. The interfacial electron density profiles derived from the structure factor analysis of the measured data show the existence of multiple layers of adsorbed water with additional peculiar metal adsorption near the oxide surfaces.Surface relaxation, depletion, and interaction between the adsorbed layers and bulk water are found to vary greatly between the two surfaces and are also different when compared to the previously studied (110) surface. The fractional ratio between chemisorbed and physisorbed water species were also quantitatively estimated, which turned out to vary dramatically from surface to surface. Finally, the result gives us a unique opportunity to reconsider the simplified 2:1 relation between chemisorption and physisorption, originally proposed by Morimoto et al. based on the adsorption isotherms of water on powder metal oxide samples.

  13. Effects of Different Surface Treatment Methods and MDP Monomer on Resin Cementation of Zirconia Ceramics an In Vitro Study

    PubMed Central

    Tanış, Merve Çakırbay; Akçaboy, Cihan

    2015-01-01

    Introduction: Resin cements are generally preferred for cementation of zirconia ceramics. Resin bonding of zirconia ceramics cannot be done with the same methods of traditional ceramics because zirconia is a silica-free material. In recent years, many methods have been reported in the literature to provide the resin bonding of zirconia ceramics. The purpose of this in vitro study is to evaluate effects of different surface treatments and 10-metacryloxydecyl dihydrogen phosphate (MDP) monomer on shear bond strength between zirconia and resin cement. Methods: 120 zirconia specimens were treated as follows: Group I: sandblasting, group II: sandblasting + tribochemical silica coating + silane, group III: sandblasting + Nd:YAG (neodymium: yttrium-aluminum-garnet) laser. One specimen from each group was evaluated under scanning electron microscope (SEM). Specimens in each group were bonded either with conventional resin cement Variolink II or with a MDP containing resin cement Panavia F2.0. Subgroups of bonded specimens were stored in distilled water (37°C) for 24 hours or 14 days. Following water storage shear bond strength test was performed at a crosshead speed of 1 mm/min in a universal test machine. Then statistical analyses were performed. Results: Highest shear bond strength values were observed in group II. No significant difference between group I and III was found when Panavia F2.0 resin cement was used. When Variolink II resin cement was used group III showed significantly higher bond strength than group I. In group I, Panavia F2.0 resin cement showed statistically higher shear bond strength than Variolink II resin cement. In group II no significant difference was found between resin cements. No significant difference was found between specimens stored in 37°C distilled water for 24 hours and 14 days. In group I surface irregularities with sharp edges and grooves were observed. In group II less roughened surface was observed with silica particles. In group

  14. Comparison of the surface roughness of feldspathic porcelain polished with a novel alumina-zirconia paste or diamond paste.

    PubMed

    Yamockul, Suparaksa; Thamrongananskul, Niyom; Poolthong, Suchit

    2016-01-01

    This study compared the surface roughness of feldspathic porcelain polished with newly developed alumina-zirconia pastes or diamond paste. Porcelain discs were prepared and polished with sandpaper using a polishing-machine. The surface roughness (Ra) of each sample was measured using a profilometer. The samples were randomly divided into 6 groups (n=10). The control group was polished with diamond paste (DP), and the five remaining groups were polished with the newly developed alumina-zirconia paste with the following ratios of glycerin:alumina:zirconia by weight: 1:0.5:0.5 (Z0.5), 1:0.5:0.75 (Z0.75), 1:0.5:1 (Z1), 1:0.5:1.5 (Z1.5), and 1:0.5:2 (Z2). The specimens were polished for 120 s. The Ra values were determined again and the surface morphology of the porcelain samples was analyzed using SEM. The Ra values decreased as the amount of zirconia in the polishing paste increased, except for the Z2 group. The surface roughness as observed by SEM showed a correlation with the Ra values.

  15. Effects of grinding on properties of Mg-PSZ ceramics prepared by the surface enrichment of zirconia powders

    SciTech Connect

    Deb, S.; Das, S.R.

    1995-10-01

    Commercial grade zirconia powders of mean particle size of 3.21 microns were super-ground in wet condition in alcoholic medium in a Planetary Ball-Mill for 12-hours using a zirconia pot as well as balls, in order to avoid contaminations from the grinding media. Sedigraph analysis data show the mean particle sizes within the range of 0.4 to 0.2 micron. The super-ground zirconia powders were then treated with appropriate acid and alkali solutions in order to enrich the surfaces of zirconia powders. The chemical analysis reports depict the enrichment phenomena of the processed zirconia powders. Magnesium oxide of different mole percentages (3 to 9%) have been incorporated to the above super-ground and enriched zirconia powder and green specimens were prepared by pressing with a suitable pressure of 200 MPa to yield the green compaction density of 3.06 gm/cm{sup 3}. The compacted green specimens were sintered without pressure at 1,480 C in air followed by normal cooling. X-ray diffraction patterns of the above sintered and cooled specimens have confirmed the formation of Mg-PSZ ceramics with 40% tetragonal phase. The sintered PSZ-products have shown very good surface properties but at the cost of transverse rupture strength. The effects of grinding were observed on the above Mg-PSZ ceramics which exhibit very little change in the tetragonal phase even after 30-minutes of grinding with a 60-mesh diamond wheel at a normal pressure of 4 kg/cm{sup 2}.

  16. Surface modification of zirconia with polydopamine to enhance fibroblast response and decrease bacterial activity in vitro: A potential technique for soft tissue engineering applications.

    PubMed

    Liu, Mingyue; Zhou, Jianfeng; Yang, Yang; Zheng, Miao; Yang, Jianjun; Tan, Jianguo

    2015-12-01

    The quality of soft-tissue integration plays an important role in the short- and long-term success of dental implants. The aim of the present study was to provide a surface modification approach for zirconia implant abutment materials and to evaluate its influence on fibroblast behavior and oral bacteria adhesion, which are the two main factors influencing the quality of peri-implant soft-tissue seal. In this study, polydopamine (PDA)-coated zirconia was prepared and the surface characteristics were evaluated using scanning electron microscopy, atomic force microscopy, a contact-angle-measuring device, X-ray photoelectron spectroscopy, and Raman spectroscopy. The responses of human gingival fibroblasts (HGFs) to PDA-coated zirconia; i.e., adhesion, proliferation, morphology, protein synthesis, and gene expression, were analyzed. Additionally, the adhesion of Streptococcus gordonii and Streptococcus mutans to zirconia after PDA coating was assessed by scanning electron microscopy and live/dead staining. The material surface analyses suggested the successful coating of PDA onto the zirconia surface. The PDA coating significantly increased cell adhesion and proliferation compared with pristine zirconia. HGFs exhibited a high degree of spreading and secreted a high level of collagen type I on PDA-modified disks. Upregulation of integrin α5, β1, β3 and fibronectin was noted in HGFs cultured on PDA-coated zirconia. The number of adherent bacteria decreased significantly on zirconia after PDA coating. In summary, our result suggest that PDA is able to modify the surface of zirconia, influence HGFs' behavior and reduce bacterial adhesion. Therefore, this surface modification approach holds great potential for improving soft-tissue integration around zirconia abutments in clinical application. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Bond strength of three luting agents to zirconia ceramic - Influence of surface treatment and thermocycling

    PubMed Central

    ATTIA, Ahmed

    2011-01-01

    Objective This in vitro study aimed to evaluate the influence of different surface treatments, 3 luting agents and thermocycling on microtensile bond strength (µTBS) to zirconia ceramic. Material and Methods A total of 18 blocks (5x5x4 mm) were fabricated from zirconia ceramic (ICE Zirkonia) and duplicated into composite blocks (Alphadent). Ceramic blocks were divided into 3 groups (n=6) according to the following surface treatments: airborne-particle abrasion (AA), silica-coating, (SC) (CoJet) and silica coating followed by silane application (SCSI) (ESPE Sil). Each group was divided into 3 subgroups (n=2) according to the 3 luting agents used. Resin-modified glass-ionomer cement (RMGIC, Ketac Cem Plus), self-adhesive resin cement (UN, RelyX Unicem) and adhesive resin cement (ML, MultiLink Automix) were used for bonding composite and zirconia blocks. Each bonding assembly was cut into microbars (10 mm long and 1±0.1 mm2). Seven specimens of each subgroup were stored in water bath at 37ºC for 1 week. The o ther 7 specimens were stored in water bath at 37ºC for 30 days then thermocycled (TC) for 7,500 cycles. µTBS values were recorded for each specimen using a universal testing machine. Statistical analyses were performed using a 3-way ANOVA model followed by serial 1-way ANOVAs. Comparison of means was performed with Tukey's HSD test at (α=0.05). Results µTBS ranged from 16.8 to 31.8 MPa after 1 week and from 7.3 to 16.4 MPa after 30 days of storage in water and thermocycling. Artificial aging significantly decreased µTBS (p<0.05). Considering surface treatment, SCSI significantly increased µTBS (p<0.05) compared to SC and AA. Resin cements (UN and ML) demonstrated significantly higher µTBS (p<0.05) compared to RMGIC cement. Conclusions Silica coating followed by silane application together with adhesive resin cements significantly increased µTBS, while thermocycling significantly decreased µTBS. PMID:21710091

  18. A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia.

    PubMed

    Liu, Juan; Hong, Guang; Wu, Yu-Han; Endo, Kosei; Han, Jian-Min; Kumamoto, Hiroyuki; Wada, Takeshi; Kato, Hidemi; Gao, Ping; Sasaki, Keiichi

    2017-11-01

    The aim of this study was to investigate and compare the surface characteristics and initial bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) with those of yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi) following the use of three surface modification methods; polishing, sandblasting/acid-etching (SB-E) and electrochemical deoxidation (ECD). Physical properties including surface morphology, chemical composition, X-ray diffraction, surface wettability, surface roughness, and hardness were measured. Osteoblast-like MC3T3-E1 cells were used to examine cell morphology and attachment to the surfaces of the materials. ECD treated NANOZR (NANOZR-E) showed a well-arranged, self-organized microporous surface structure with significantly low contact angles when compared with the other specimens (p < 0.05). NANOZR-E also demonstrated a slight decrease in monoclinic phase content (-4.4 wt %). The morphology and attachment of MC3T3-E1 cells on NANOZR-E were similar to those on polished and SBE-treated CpTi surfaces. Higher cell affinity was observed on NANOZR-E when compared with ECD treated 3Y-TZP. The findings of this study indicate the effectiveness of the novel technique, ECD, in the formation of a microporous surface on NANOZR when compared with both CpTi and 3Y-TZP. Moreover, this method also appears to improve the biological activity of NANOZR during the initial stage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2641-2652, 2017. © 2016 Wiley Periodicals, Inc.

  19. Low-Fusing Porcelain Glaze Application on 3Y-TZP Surfaces can Enhance Zirconia-Porcelain Adhesion.

    PubMed

    Yamamoto, Lígia Tiaki; Rodrigues, Vinícius Anéas; Dornelles, Lucio Strazzabosco; Bottino, Marco Antonio; Valandro, Luiz Felipe; Melo, Renata Marques de

    2016-01-01

    The aim of this study was to assess whether surface treatment improves zirconia-porcelain adhesion. The 3Y-TZP blocks were cut into squares, then polished and sintered. The zirconia surface treatments were performed as follows: no treatment (C); tribochemical silica coating (TBS); glaze application + hydrofluoric acid etching (GA); glaze application + hydrofluoric acid etching + silanization (GAS); deposition of silica nanofilm (NF). After treatments, veneering porcelain cylinders (3.3 x 3.3 mm) were built up on all specimens and fired. Then the specimens were subjected to thermal cycling (6000 cycles), and subjected to shear test. Fractures were analyzed by stereomicroscopy and SEM. Data were statistically analyzed by 1-way ANOVA and Tukey's test (5%). Zirconia-porcelain bond strength was affected by the ceramic surface treatments (p=0.0001). GA (19.5±3 MPa) and GAS (16.2±4 MPa) recorded the highest bond strength values, while control group had the lowest bond value (10.1±4 MPa). Adhesive failure of the samples predominated. Therefore, glaze application as 3Y-TZP treatment before veneering porcelain stratification may enhance zirconia-porcelain adhesion.

  20. Influence of Pre-Sintered Zirconia Surface Conditioning on Shear Bond Strength to Resin Cement

    PubMed Central

    Sawada, Tomofumi; Spintzyk, Sebastian; Schille, Christine; Zöldföldi, Judit; Paterakis, Angelos; Schweizer, Ernst; Stephan, Ingrid; Rupp, Frank; Geis-Gerstorfer, Jürgen

    2016-01-01

    This study analyzed the shear bond strength (SBS) of resin composite on zirconia surface to which a specific conditioner was applied before sintering. After sintering of either conditioner-coated or uncoated specimens, both groups were divided into three subgroups by their respective surface modifications (n = 10 per group): no further treatment; etched with hydrofluoric acid; and sandblasted with 50 µm Al2O3 particles. Surfaces were characterized by measuring different surface roughness parameters (e.g., Ra and Rmax) and water contact angles. Half of the specimens underwent thermocycling (10,000 cycles, 5–55 °C) after self-adhesive resin cement build-up. The SBSs were measured using a universal testing machine, and the failure modes were analyzed by microscopy. Data were analyzed by nonparametric and parametric tests followed by post-hoc comparisons (α = 0.05). Conditioner-coated specimens increased both surface roughness and hydrophilicity (p < 0.01). In the non-thermocycled condition, sandblasted surfaces showed higher SBSs than other modifications, irrespective of conditioner application (p < 0.05). Adhesive fractures were commonly observed in the specimens. Thermocycling favored debonding and decreased SBSs. However, conditioner-coated specimens upon sandblasting showed the highest SBS (p < 0.05) and mixed fractures were partially observed. The combination of conditioner application before sintering and sandblasting after sintering showed the highest shear bond strength and indicated improvements concerning the failure mode. PMID:28773641

  1. Current status of zirconia restoration.

    PubMed

    Miyazaki, Takashi; Nakamura, Takashi; Matsumura, Hideo; Ban, Seiji; Kobayashi, Taira

    2013-10-01

    During the past decade, zirconia-based ceramics have been successfully introduced into the clinic to fabricate fixed dental prostheses (FDPs), along with a dental computer-aided/computer-aided manufacturing (CAD/CAM) system. In this article (1) development of dental ceramics, (2) the current status of dental CAD/CAM systems, (3) CAD/CAM and zirconia restoration, (4) bond between zirconia and veneering ceramics, (5) bond of zirconia with resin-based luting agents, (6) surface finish of zirconia restoration and antagonist enamel wear, and (7) clinical evaluation of zirconia restoration are reviewed. Yttria partially stabilized tetragonal zirconia polycrystalline (Y-TZP) showed better mechanical properties and superior resistance to fracture than other conventional dental ceramics. Furthermore, ceria-stabilized tetragonal zirconia polycrystalline and alumina nanocomposites (Ce-TZP/A) had the highest fracture toughness and had resistance to low-temperature aging degradation. Both zirconia-based ceramics have been clinically available as an alternative to the metal framework for fixed dental prostheses (FDPs). Marginal adaptation of zirconia-based FDPs is acceptable for clinical application. The most frequent clinical complication with zirconia-based FDPs was chipping of the veneering porcelain that was affected by many factors. The mechanism for the bonding between zirconia and veneering ceramics remains unknown. There was no clear evidence of chemical bonding and the bond strength between zirconia and porcelain was lower than that between metal and porcelain. There were two alternatives proposed that might avoid chipping of veneering porcelains. One was hybrid-structured FDPs comprising CAD/CAM-fabricated porcelain parts adhering to a CAD/CAM fabricated zirconia framework. Another option was full-contour zirconia FDPs using high translucent zirconia. Combined application of silica coating and/or silane coupler, and 10-methacryloyloxydecyl dihydrogen phosphate is

  2. Characterization of Human Gingival Fibroblasts on Zirconia Surfaces Containing Niobium Oxide

    PubMed Central

    Cho, Young-Dan; Shin, Ji-Cheol; Yoon, Hyung-In; Ku, Young; Ryoo, Hyun-Mo; Kim, Dae-Joon; Kim, Do-Gyoon; Han, Jung-Suk

    2015-01-01

    It was indicated that tetragonal zirconia polycrystal (TZP) containing yttria (Y2O3) and niobium oxide (Nb2O5) ((Y,Nb)-TZP) could be an adequate dental material to be used at esthetically important sites. The (Y,Nb)-TZP was also proved to possess its osteogenic potential comparable with those conventional dental implant material, titanium (Ti). The objective of the current study was to characterize cellular response of human gingival fibroblasts (HGFs) to smooth and rough surfaces of the (Y,Nb)-TZP disc, which were obtained by polishing and sandblasting, respectively. Various microscopic, biochemical, and molecular techniques were used to investigate the disc surfaces and cellular responses for the experimental (Y,Nb)-TZP and the comparing Ti groups. Sandblasted rough (Y,Nb)-TZP (Zir-R) discs had the highest surface roughness. HGFs cultured on polished (Y,Nb)-TZP (Zir) showed a rounded cell morphology and light spreading at 6 h after seeding and its proliferation rate significantly increased during seven days of culture compared to other surfaces. The mRNA expressions of type I collagen, integrin α2 and β1 were significantly stimulated for the Zir group at 24 h after seeding. The current findings, combined with the previous results, indicate that (Y,Nb)-TZP provides appropriate surface condition for osseointegration at the fixture level and for peri-implant mucosal sealing at the abutment level producing a suitable candidate for dental implantation with an expected favorable clinical outcome. PMID:28793548

  3. High surface area calcite

    NASA Astrophysics Data System (ADS)

    Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

    2013-05-01

    Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

  4. Comparison of the bulk and surface properties of ceria and zirconia by ab initio investigations

    SciTech Connect

    Gennard, S.; Cora, F.; Catlow, C.R.A.

    1999-11-18

    Quantum mechanical (QM) calculations were made at a periodic Hartree-Fock (HF) level, on the bulk and surface properties of cubic CeO{sub 2} and ZrO{sub 2}. The authors have investigated the M-O bonding features, and established the high degree of ionicity of both materials, which is greater for CeO{sub 2} than ZrO{sub 2}. The calculated values for the C{sub 11}, C{sub 12}, and C{sub 44} elastic constants, are in close agreement with experiment; an extended oxygen basis set, containing d-orbital polarization functions, is essential to model accurately the symmetry lowering during the C{sub 44} distortion. In the surface studies, they have calculated the surface energies of the {l{underscore}brace}011{r{underscore}brace} and {l{underscore}brace}111{r{underscore}brace} faces of both ceria and zirconia. QM results are compared with interatomic potential-based (IP) methods to assess the accuracy of the latter. IP methods were found to provide a correct estimate of the surface relaxations and the correct order of stability of the two faces examined, with the energy difference between the {l{underscore}brace}011{r{underscore}brace} and the {l{underscore}brace}111{r{underscore}brace} surfaces being approximately 1 J/m{sup 2}, as in the QM study. However, IP methods do not always discriminate adequately between the properties of the two materials. Finally, geometric and electronic relaxations in the {l{underscore}brace}111{r{underscore}brace} surface are confined to the outermost oxygen ions, while in the {l{underscore}brace}011{r{underscore}brace} slabs they are more important and extend to the subsurface layers in a columnar way. The unsaturation of the surface ions in the {l{underscore}brace}011{r{underscore}brace} face may have important implications for the catalytic activity of the materials.

  5. Influences of multiple firings and aging on surface roughness, strength and hardness of veneering ceramics for zirconia frameworks.

    PubMed

    Tang, Xuehua; Luo, Huinan; Bai, Yang; Tang, Hui; Nakamura, Takashi; Yatani, Hirofumi

    2015-09-01

    To evaluate the effects of multiple firings and aging on surface roughness, strength, and hardness of veneering ceramics for zirconia frameworks. Five different veneering ceramics for zirconia frameworks were used: Vintage ZR (ZR), Cerabien ZR (CZR), VitaVM9 (VM9), Cercon ceram KISS (KISS), and IPS e.max ceram (e.max). Specimens were fired 2 or 10 times in order to accelerate aging. Surface roughness was evaluated using laser profilometry. Flexural strength and Vickers hardness were also measured. Surface topography was observed using scanning electron microscopy. After accelerated aging, the surface roughness of all specimens fired 10 times was significantly lower than that of the same specimens fired 2 times (P=0.000). Except for VM9, the flexural strength of all specimens fired 10 times was greater than that of the same specimens fired 2 times, and the differences were significant for ZR and CZR (P<0.01). The flexural strength of VM9 fired 10 times was significantly lower than that of VM9 fired 2 times (P=0.034). The Vickers hardness of ZR and VM9 fired 10 times was significantly higher than that of the same specimens fired 2 times (P<0.05), but that of KISS fired 10 times was significantly lower than that of KISS fired 2 times (P=0.000). Multiple firings had a positive effect on the surface roughness of all aged veneering ceramics used for zirconia restorations and on the strength and hardness of many aged veneering ceramics used for zirconia restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications.

    PubMed

    Laranjeira, Marta S; Carvalho, Ângela; Pelaez-Vargas, Alejandro; Hansford, Derek; Ferraz, Maria Pia; Coimbra, Susana; Costa, Elísio; Santos-Silva, Alice; Fernandes, Maria Helena; Monteiro, Fernando Jorge

    2014-04-01

    Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol-gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior.

  7. Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications

    PubMed Central

    Laranjeira, Marta S; Carvalho, Ângela; Pelaez-Vargas, Alejandro; Hansford, Derek; Ferraz, Maria Pia; Coimbra, Susana; Costa, Elísio; Santos-Silva, Alice; Fernandes, Maria Helena; Monteiro, Fernando Jorge

    2014-01-01

    Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol–gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior. PMID:27877662

  8. Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications

    NASA Astrophysics Data System (ADS)

    Laranjeira, Marta S.; Carvalho, Ângela; Pelaez-Vargas, Alejandro; Hansford, Derek; Ferraz, Maria Pia; Coimbra, Susana; Costa, Elísio; Santos-Silva, Alice; Fernandes, Maria Helena; Monteiro, Fernando Jorge

    2014-04-01

    Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol-gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior.

  9. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    NASA Astrophysics Data System (ADS)

    Sherly, K. B.; Rakesh, K.

    2014-01-01

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl2ṡ8H2O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  10. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    SciTech Connect

    Sherly, K. B.; Rakesh, K.

    2014-01-28

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}⋅8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  11. Thermocycling effect on microshear bond strength to zirconia ceramic using Er:YAG and tribochemical silica coating as surface conditioning.

    PubMed

    Gomes, Ana Luísa; Ramos, João Carlos; Santos-del Riego, Sérgio; Montero, Javier; Albaladejo, Alberto

    2015-02-01

    The purpose of this study is to evaluate the thermocycling effect on the microshear bond strength (μSBS) of different self-adhesive resin cements to zirconia using tribochemical silica coating Rocatec™ (ROC) and Er:YAG as surface conditioners. Two hundred forty square-like zirconia samples were polished and randomly assigned in four groups according surface treatment applied as follows: (1) no treatment (NT), (2) silica coating with ROC, 3) Er:YAG laser irradiation (LAS: 2.940 nm, 200 mJ; 10 Hz), and (4) laser followed by Rocatec™ (LAROC). Each group was divided into two subgroups according the resin tested as follows: (A) BiFix SE (BIF) and (B) Clearfil SA (CLE). After 24 h, half of the specimens from each subgroup were tested. The other half was stored and thermocycled (5-55 °C/5,000 cycles). A μSBS test was performed using a universal testing machine (cross head speed = 0.5 mm/min). Failure modes were recorded and observed by scanning electronic microscopy. Data was analyzed with ANOVA, Student's t test, and chi-square tests, and linear regression was performed (p < 0.05). Before thermocycling, both cements showed higher μSBS results with ROC and LAROC. After aging, (1) all BIF specimens evidenced severely decreased adhesion with mostly adhesive failures and (2) CLE maintained the initial results in ROC and LAROC groups, performing better with ROC. Thermocycling did not negatively influence the resin-zirconia μSBS results in the self-adhesive resin cement containing 10-MDP when used on zirconia surface coated with silica, independently of previous Er:YAG surface treatment.

  12. Surface Roughness Prediction Model using Zirconia Toughened Alumina (ZTA) Turning Inserts: Taguchi Method and Regression Analysis

    NASA Astrophysics Data System (ADS)

    Mandal, Nilrudra; Doloi, Biswanath; Mondal, Biswanath

    2016-01-01

    In the present study, an attempt has been made to apply the Taguchi parameter design method and regression analysis for optimizing the cutting conditions on surface finish while machining AISI 4340 steel with the help of the newly developed yttria based Zirconia Toughened Alumina (ZTA) inserts. These inserts are prepared through wet chemical co-precipitation route followed by powder metallurgy process. Experiments have been carried out based on an orthogonal array L9 with three parameters (cutting speed, depth of cut and feed rate) at three levels (low, medium and high). Based on the mean response and signal to noise ratio (SNR), the best optimal cutting condition has been arrived at A3B1C1 i.e. cutting speed is 420 m/min, depth of cut is 0.5 mm and feed rate is 0.12 m/min considering the condition smaller is the better approach. Analysis of Variance (ANOVA) is applied to find out the significance and percentage contribution of each parameter. The mathematical model of surface roughness has been developed using regression analysis as a function of the above mentioned independent variables. The predicted values from the developed model and experimental values are found to be very close to each other justifying the significance of the model. A confirmation run has been carried out with 95 % confidence level to verify the optimized result and the values obtained are within the prescribed limit.

  13. Surface modification of yttria stabilized zirconia via polydopamine inspired coating for hydroxyapatite biomineralization

    NASA Astrophysics Data System (ADS)

    Zain, Norhidayu Muhamad; Hussain, Rafaqat; Kadir, Mohammed Rafiq Abdul

    2014-12-01

    Yttria stabilized zirconia (YSZ) has been widely used as biomedical implant due to its high strength and enhanced toughening characteristics. However, YSZ is a bioinert material which constrains the formation of chemical bonds with bone tissue following implantation. Inspired by the property of mussels, the surface of YSZ ceramics was functionalized by quinone-rich polydopamine to facilitate the biomineralization of hydroxyapatite. YSZ discs were first immersed in 2 mg/mL of stirred or unstirred dopamine solution at either 25 or 37 °C. The samples were then incubated in 1.5 simulated body fluid (SBF) for 7d. The effect of coating temperature for stirred and unstirred dopamine solutions during substrate grafting was investigated on the basis of chemical compositions, wettability and biomineralization of hydroxyapatite on the YSZ functionalized surface. The results revealed that the YSZ substrate grafted at 37 °C in stirred solution of dopamine possessed significantly improved hydrophilicity (water contact angle of 44.0 ± 2.3) and apatite-mineralization ability (apatite ratio of 1.78). In summary, the coating temperature and stirring condition during grafting procedure affected the chemical compositions of the films and thus influenced the formation of apatite layer on the substrate during the biomineralization process.

  14. Synthesis and characterization of mesoporous zirconia and aluminated mesoporous zirconia

    NASA Astrophysics Data System (ADS)

    Zhao, Elizabeth Sun

    Synthesis of mesoporous zirconia has been performed by slowly hydrolyzing zirconium propoxide in the presence of anionic surfactants: namely, dodecyl phosphate or sulfate (P12 and Sf12) and hexadecyl sulfonate (So16) The zirconia. outgassed at 140--150°C has T-plot surface areas higher than 400 M2/g. This outgassing does not remove the surfactant. After calcination in air at 500°C and combustion of the surfactant, the mesoporous volume is reduced by a factor of about 2, whereas the pore wall material crystallizes in the tetragonal phase. The high-resolution electron microscopic study reveals the presence of a disorganized network of polygonal pores structure. It is suggested that the chemistry of the hydrolysis solution is instrumental in determining the pore structure. A schematic model in which the surfactant is a scaffold component is suggested in order to explain these results and the fixation of PO4, or SO4 in the walls may help to preserve the porous structure. It is very different from the templating mechanism. From the density obtained from phase transition temperature, and from the mesoporous volume (N2 adsorption), the thickness of the wall can be calculated as well as the pseudo-length of the pores. From the thickness, the T-plot area can be recalculated and agrees well with the measured T-plot surface area for the sample calcined at 500°C. Around 900°C, the walls become thicker and crystallizes into monoclinic zirconia without pore structure. In order to try to modify, the acidity of the mesoporous sulfated and oxo-phosphated zirconia, they were doped with aluminum. The sulfated zirconia only has a coating layer of amorphous alumina, while the phosphated zirconia has aluminum in the lattice and the alumina coat. A maximum ratio of Al/Zr ˜ 0.04 can be reached in the lattice. The introduction of aluminum into the lattice prevents the crystallization of the oxo-phosphate at 900°C, and helps to preserve the surface area and porosity of the sulfated

  15. 3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

    PubMed

    Osman, Reham B; van der Veen, Albert J; Huiberts, Dennis; Wismeijer, Daniel; Alharbi, Nawal

    2017-11-01

    The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Deformation characteristics of the near-surface layers of zirconia ceramics implanted with aluminum ions

    NASA Astrophysics Data System (ADS)

    Ghyngazov, S. A.; Vasiliev, I. P.; Frangulyan, T. S.; Chernyavski, A. V.

    2015-10-01

    The effect of ion treatment on the phase composition and mechanical properties of the near-surface layers of zirconium ceramic composition 97 ZrO2-3Y2O3 (mol%) was studied. Irradiation of the samples was carried out by accelerated ions of aluminum with using vacuum-arc source Mevva 5-Ru. Ion beam had the following parameters: the energy of the accelerated ions E = 78 keV, the pulse current density Ji = 4mA / cm2, current pulse duration equal τ = 250 mcs, pulse repetition frequency f = 5 Hz. Exposure doses (fluence) were 1016 и 1017 ion/cm2. The depth distribution implanted ions was studied by SIMS method. It is shown that the maximum projected range of the implanted ions is equal to 250 nm. Near-surface layers were investigated by X-ray diffraction (XRD) at fixed glancing incidence angle. It is shown that implantation of aluminum ions into the ceramics does not lead to a change in the phase composition of the near-surface layer. The influence of implanted ions on mechanical properties of ceramic near-surface layers was studied by the method of dynamic nanoindentation using small loads on the indenter P=300 mN. It is shown that in ion- implanted ceramic layer the processes of material recovery in the deformed region in the unloading mode proceeds with higher efficiency as compared with the initial material state. The deformation characteristics of samples before and after ion treatment have been determined from interpretation of the resulting P-h curves within the loading and unloading sections by the technique proposed by Oliver and Pharr. It was found that implantation of aluminum ions in the near-surface layer of zirconia ceramics increases nanohardness and reduces the Young's modulus.

  17. Effect of Different Surface Treatments on the Bond Strength of Lithium Disilicate Ceramic to the Zirconia Core.

    PubMed

    Yilmaz-Savas, Tuba; Demir, Necla; Ozturk, A Nilgun; Kilic, Hamdi Sukur

    2016-06-01

    The aim of this study was to evaluate the effect of different surface treatments [sandblasting, Erbium:Yttrium-Aluminium-Garnet (Er:YAG), and femtosecond lasers] on the shear bond strength (SBS) of the CAD-on technique. Although demand for all-ceramic restorations has increased, chipping remains one of the major problems for zirconia-based restorations. Forty yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) zirconia plates (IPS e.max ZirCAD, Ivoclar Vivadent) were cut, sintered (12.4 × 11.4 × 3 mm) and divided into four groups according to the surface treatments (n = 10): a control group with no surface treatment (Group C), sandblasting with 50 μm Al2O3 (Group S), Er:YAG laser irradiation (Group E), and femtosecond laser irradiation (Group F). Also, 40 cylindrical (5 mm diameter, 2 mm height) lithium disilicate (IPS e.max CAD) veneer ceramics were cut and fused to all zirconia cores by a glass-fusion ceramic and crystallized according to the CAD-on technique. Specimens were subjected to shear force using a universal testing machine. The load was applied at a crosshead speed of 0.5 mm/min until failure. Mean SBS (MPa) were analyzed with one way ANOVA (p < 0.05). The failed specimens were examined under a stereomicroscope at ×20 to classify the mode of failure. The highest SBS was observed in Group F (36 ± 3.31 MPa), followed by Group S (33.03 ± 5.05 MPa), and Group C (32.52 ± 10.15 MPa). The lowest SBS was observed in Group E (31.02 ± 4.96 MPa), but no significant differences were found between the control and surface treated groups (p = 0.377). All the specimens showed a mixed type of failure. Femtosecond laser application increased the bond strength between zirconia-veneer specimens. However, the novel CAD-on technique with no surface treatment also showed high bonding strength. Thus, this technique could prevent ceramic chipping without additional surface treatments.

  18. Effect of different surface treatments on shear bond strength of zirconia to three resin cements

    NASA Astrophysics Data System (ADS)

    Dadjoo, Nisa

    Statement of problem: There are no standard guidelines for material selection to obtain acceptable bonding to high-strength zirconium oxide ceramic. Studies suggest resin cements in combination with MDP-containing primer is a reasonable choice, however, the other cements cannot be rejected and need further investigation. Objective: The purpose of this in vitro study was the evaluation of the shear bond strength of three composite resin cements to zirconia ceramic after using different surface conditioning methods. Materials and methods: One hundred and twenty sintered Y-TZP ceramic (IPS e.max ZirCAD) squares (8 x 8 x 4 mm) were embedded in acrylic molds, then divided into three groups (n=40) based on the type of cement used. Within each group, the specimens were divided into four subgroups (n=10) and treated as follows: (1) Air abrasion with 50microm aluminum oxide (Al2O 3) particles (ALO); (2) Air abrasion + Scotchbond Universal adhesive (SBU); (3) Air abrasion + Monobond Plus (MBP); (4) Air abrasion + Z-Prime Plus (ZPP). Composite cylinders were used as carriers to bond to conditioned ceramic using (1) RelyX Ultimate adhesive resin cement (RX); (2) Panavia SA self-adhesive resin cement (PSA); (3) Calibra esthetic cement (CAL). The bonded specimens were submerged in distilled water and subjected to 24-hour incubation period at 37°C. All specimens were stressed in shear at a constant crosshead speed of 0.5 mm/min until failure. Statistical analysis was performed by ANOVA. The bond strength values (MPa), means and standard deviations were calculated and data were analyzed using analysis of variance with Fisher's PLSD multiple comparison test at the 0.05 level of significance. The nature of failure was recorded. Results: The two-way ANOVA showed Panavia SA to have the highest strength at 44.3 +/- 16.9 MPa (p<0.05). The combination of Scotchbond Universal surface treatment with Panavia SA cement showed statistically higher bond strength (p=0.0054). The highest bond

  19. Effects of different surface treatments on bond strength between resin cements and zirconia ceramics.

    PubMed

    Erdem, A; Akar, G C; Erdem, A; Kose, T

    2014-01-01

    This study compares the bond strength of resin cement and yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic with different surface conditioning methods. Two hundred presintered Y-TZP ceramic specimens were prepared, sintered (4 × 4 × 4 mm), and randomly assigned to four equal groups as control (C, no conditioning); airborne particle abraded (APA, air abrasion with 11 μm Al2O3); tribochemical silica coating/silane coupling system (TSC, Rocatec, air abrasion with 110 μm Al2O3, 30 μm silica-coated Al2O3 and silane); and laser (L, Er:YAG laser irradiation treated at a power setting of 200 mJ). After specimen preparation, composite resin cylinders were prepared and cemented with resin cements (Clearfil Esthetic, Panavia F 2.0, Rely X-U100, Super Bond C&B, and Multilink Automix) on the ceramic surfaces and kept in an incubator at 37°C for 60 days. All specimens were tested for shear bond strength with a universal testing machine, and fractured surfaces were evaluated by environmental scanning electron microscopy. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05). The bond strengths for C and L groups were not significantly different according to adhesive resin cement. APA and TSC resulted in increased bond strength for Panavia F 2.0 and Rely X-U100 resin cements. Additionally, TSC presented higher bond strength with Multilink Automix. Adhesive fracture between the ceramic and resin cement was the most common failure. Complete cohesive fracture at the ceramic or composite cylinders was not observed. Regardless of the adhesive resin cement used, laser treatment did not improve resin bond strength.

  20. Zirconia in fixed implant prosthodontics.

    PubMed

    Guess, Petra Christine; Att, Wael; Strub, Joerg Rudolf

    2012-10-01

    CAD/CAM technology in combination with zirconia ceramic has increasingly gained popularity in implant dentistry. This narrative review presents the current knowledge on zirconia utilized as framework material for implant-borne restorations and implant abutments, laboratory tests and developments, clinical performance, and possible future trends for implant dentistry are addressed. A review of available literature from 1990 through 2010 was conducted with search terms zirconia,"implants,"abutment,"crown," and "fixed dental prosthesis" using electronic databases (PubMed) and manual searching. Latest applications of zirconia in implant dentistry include implant abutments, multiple unit and full-arch frameworks as well as custom-made bars to support fixed and removable prostheses. High biocompatibility, low bacterial surface adhesion as well as favorable chemical properties of zirconia ceramics are reported. Zirconia stabilized with yttrium oxide exhibits high flexural strength and fracture toughness due to a transformation toughening mechanism. Preliminary clinical data confirmed the high stability of zirconia for abutments and as a framework material for implant borne crowns and fixed dental prostheses. Zirconia abutment or framework damage has rarely been encountered. However, veneering porcelain fractures are the most common technical complication in implant-supported zirconia restorations. These porcelain veneer failures have led to concerns regarding differences in coefficient of thermal expansions between core and veneering porcelain and their respective processing techniques. As presently evidence of clinical long-term data is missing, caution with regard to especially extensive implant-borne zirconia frameworks is recommended. © 2010 Wiley Periodicals, Inc.

  1. Effect of surface conditioning modalities on the repair bond strength of resin composite to the zirconia core / veneering ceramic complex.

    PubMed

    Ozcan, Mutlu; Valandro, Luiz Felipe; Pereira, Sarina Maciel; Amaral, Regina; Bottino, Marco Antonio; Pekkan, Gurel

    2013-06-01

    This study evaluated the effect of different surface conditioning protocols on the repair strength of resin composite to the zirconia core / veneering ceramic complex, simulating the clinical chipping phenomenon. Forty disk-shaped zirconia core (Lava Zirconia, 3M ESPE) (diameter: 3 mm) specimens were veneered circumferentially with a feldspathic veneering ceramic (VM7, Vita Zahnfabrik) (thickness: 2 mm) using a split metal mold. They were then embedded in autopolymerizing acrylic with the bonding surfaces exposed. Specimens were randomly assigned to one of the following surface conditioning protocols (n = 10 per group): group 1, veneer: 4% hydrofluoric acid (HF) (Porcelain Etch) + core: aluminum trioxide (50-µm Al2O3) + core + veneer: silane (ESPE-Sil); group 2: core: Al2O3 (50 µm) + veneer: HF + core + veneer: silane; group 3: veneer: HF + core: 30 µm aluminum trioxide particles coated with silica (30 µm SiO2) + core + veneer: silane; group 4: core: 30 µm SiO2 + veneer: HF + core + veneer: silane. Core and veneer ceramic were conditioned individually but no attempt was made to avoid cross contamination of conditioning, simulating the clinical intraoral repair situation. Adhesive resin (VisioBond) was applied to both the core and the veneer ceramic, and resin composite (Quadrant Posterior) was bonded onto both substrates using polyethylene molds and photopolymerized. After thermocycling (6000 cycles, 5°C-55°C), the specimens were subjected to shear bond testing using a universal testing machine (1 mm/min). Failure modes were identified using an optical microscope, and scanning electron microscope images were obtained. Bond strength data (MPa) were analyzed statistically using the non-parametric Kruskal-Wallis test followed by the Wilcoxon rank-sum test and the Bonferroni Holm correction (α = 0.05). Group 3 demonstrated significantly higher values (MPa) (8.6 ± 2.7) than those of the other groups (3.2 ± 3.1, 3.2 ± 3, and 3.1 ± 3.5 for groups 1, 2, and 4

  2. Air abrasion before and/or after zirconia sintering: surface characterization, flexural strength, and resin cement bond strength.

    PubMed

    Abi-Rached, F O; Martins, S B; Almeida-Júnior, A A; Adabo, G L; Góes, M Sousa; Fonseca, R G

    2015-01-01

    The purpose of this in vitro study was to evaluate the effect of air-abrasion/zirconia sintering order on the yttria partially stabilized tetragonal zirconia polycrystal (Y-TZP) surface characterization (roughness, morphology, and phase transformation), flexural strength (FS), and shear bond strength (SBS) to a resin cement. Y-TZP specimens were air abraded with 50-μm Al2O3 particles after (AS), before (BS), or before and after zirconia sintering (BAS). For roughness (Ra), 30 block specimens (12×12×3.0 mm; n=10) had their surfaces analyzed by a profilometer. Next, on the air-abraded surfaces of these specimens, composite resin discs (n=30) were bonded with RelyX ARC. The bonded specimens were stored for 24 hours in distilled water at 37°C before shear testing. Failure mode was determined with a stereomicroscope (20×). The surface morphology (n=2) was evaluated by SEM (500×). For the four-point flexural strength test (EMIC DL2000), 39 bar-shaped specimens (20×4.0×1.2 mm; n=13) were air abraded according to the three conditions proposed, and an additional group (nonabraded) was evaluated (n=13). The quantitative analysis of phase transformation (n=1) was completed with Rietveld refinement with X-ray diffraction data. Ra (μm) and SBS (MPa) data were analyzed by one-way analysis of variance (ANOVA) and the Tukey test (α=0.05). Pearson correlation analysis was used to determine if there was a correlation between roughness and SBS. For FS (MPa) data, one-way ANOVA and the Dunnett C-test (α=0.05) were used. The air-abrasion/zirconia sintering order influenced significantly (p<0.001) Ra, SBS, and FS. The BS and AS groups presented the highest (1.3 μm) and the lowest (0.7 μm) Ra. The highest SBS (7.0 MPa) was exhibited by the BAS group, followed by the AS group (5.4 MPa) and finally by the BS group (2.6 MPa). All groups presented 100% adhesive failure. A weak correlation (r=-0.45, p<0.05) was found between roughness and SBS. The air-abrasion/zirconia sintering

  3. Effect of various polishing systems on the surface roughness and phase transformation of zirconia and the durability of the polishing systems.

    PubMed

    Park, Chan; Vang, Mong-Sook; Park, Sang-Won; Lim, Hyun-Pil

    2017-03-01

    Although many systems are used to polish zirconia, a comparison of the performance of zirconia and feldspathic porcelain polishing systems is lacking. The purpose of this in vitro study was to compare the effects of 3 polishing systems on surface roughness, zirconia phase transformation, and durability of the polishing systems when applied to zirconia and feldspathic porcelain. Three polishing systems were evaluated: Z1, a zirconia polishing system; Z2, a zirconia polishing system, and F1, a feldspathic porcelain polishing system. Three ceramic systems were evaluated: PR and ZM zirconia specimens (diameter 15 mm, height 2 mm; 23 specimens each) and CB feldspathic porcelain specimens of the same size (15 specimens). A rough surface was created on the 3 types of specimens (15 specimens each) to model an occlusal adjustment under the same conditions. Polishing was carried out with the 3 polishing systems for 2 minutes each. Surface roughness was measured with a 3-dimensional (3D) optical profiler. The surface was also observed with a scanning electron microscopy. X-ray diffraction analysis was performed for 8 PR or ZM zirconia specimens polished by using the Z1 and Z2 systems for 8 minutes to evaluate the phase transformation of zirconia before, during, and after polishing. These specimens were compared and analyzed for phase transformation that might have occurred during the polishing of the specimens. After finishing the surface roughness experiment and the phase transformation experiment, the volumes of the polishers were measured with a 3D volume scanner and compared with those before the experiments to evaluate the durability of the polishing system. A statistical analysis of all data was performed using 2-way ANOVA and the Tukey honest significant difference test (α=.05). The 2 zirconia polishing systems (Z1, Z2) created a significantly (P<.001) smoother surface, regardless of the type of specimens used for polishing, than the feldspathic porcelain polishing

  4. Composite Nafion/sulfonated zirconia membranes: effect of the filler surface properties on proton transport characteristics

    PubMed Central

    D’Epifanio, Alessandra; Navarra, Maria Assunta; Weise, F. Christoph; Mecheri, Barbara; Farrington, Jaime; Licoccia, Silvia; Greenbaum, Steve

    2009-01-01

    Due to their strong acidity and water affinity, sulfated zirconia nanoparticles were evaluated as inorganic additives in the formation of composite Nafion-based membranes. Two types of sulfated zirconia were obtained according to the preparation experimental conditions. Sulfated zirconia-doped Nafion membranes were prepared by a casting procedure. The properties of the composite membranes were compared with those of an unfilled Nafion membrane obtained by the same preparation method. The water uptake, measured at room temperature in a wide relative humidity range, was higher for the composite membranes, this confirming the hydrophilic nature of the selected additives. The membrane doped by zirconia particles having the highest sulphate group concentration showed the highest water diffusion coefficient in the whole range of temperature and relative humidity investigated due to the presence of SO42− providing extra acid sites for water diffusion. The proton diffusivity calculated from impedance spectroscopy measurements was compared with water self diffusion coefficients measured by NMR Spectroscopy. The difference between proton and water diffusivity became significant only at high humidification levels, highlighting the role of water in the intermolecular proton transfer mechanism. Finally, great improvements were found when using the composite membrane as electrolyte in a fuel cell working at very low relative humidity. PMID:20209115

  5. Evaluation of translucency of monolithic zirconia and framework zirconia materials.

    PubMed

    Tuncel, İlkin; Turp, Işıl; Üşümez, Aslıhan

    2016-06-01

    The opacity of zirconia is an esthetic disadvantage that hinders achieving natural and shade-matched restorations. The aim of this study was to evaluate the translucency of non-colored and colored framework zirconia and monolithic zirconia. The three groups tested were: non-colored framework zirconia, colored framework zirconia with the A3 shade according to Vita Classic Scale, and monolithic zirconia (n=5). The specimens were fabricated in the dimensions of 15×12×0.5 mm. A spectrophotometer was used to measure the contrast ratio, which is indicative of translucency. Three measurements were made to obtain the contrast ratios of the materials over a white background (L(*)w) and a black background (L(*)b). The data were analyzed using the one-way analysis of variance and Tukey HSD tests. One specimen from each group was chosen for scanning electron microscope analysis. The determined areas of the SEM images were divided by the number of grains in order to calculate the mean grain size. Statistically significant differences were observed among all groups (P<.05). Non-colored zirconia had the highest translucency with a contrast ratio of 0.75, while monolithic zirconia had the lowest translucency with a contrast ratio of 0.8. The mean grain sizes of the non-colored, colored, and monolithic zirconia were 233, 256, and 361 nm, respectively. The translucency of the zirconia was affected by the coloring procedure and the grain size. Although monolithic zirconia may not be the best esthetic material for the anterior region, it may serve as an alternative in the posterior region for the bilayered zirconia restorations.

  6. Evaluation of translucency of monolithic zirconia and framework zirconia materials

    PubMed Central

    Tuncel, İlkin; Üşümez, Aslıhan

    2016-01-01

    PURPOSE The opacity of zirconia is an esthetic disadvantage that hinders achieving natural and shade-matched restorations. The aim of this study was to evaluate the translucency of non-colored and colored framework zirconia and monolithic zirconia. MATERIALS AND METHODS The three groups tested were: non-colored framework zirconia, colored framework zirconia with the A3 shade according to Vita Classic Scale, and monolithic zirconia (n=5). The specimens were fabricated in the dimensions of 15×12×0.5 mm. A spectrophotometer was used to measure the contrast ratio, which is indicative of translucency. Three measurements were made to obtain the contrast ratios of the materials over a white background (L*w) and a black background (L*b). The data were analyzed using the one-way analysis of variance and Tukey HSD tests. One specimen from each group was chosen for scanning electron microscope analysis. The determined areas of the SEM images were divided by the number of grains in order to calculate the mean grain size. RESULTS Statistically significant differences were observed among all groups (P<.05). Non-colored zirconia had the highest translucency with a contrast ratio of 0.75, while monolithic zirconia had the lowest translucency with a contrast ratio of 0.8. The mean grain sizes of the non-colored, colored, and monolithic zirconia were 233, 256, and 361 nm, respectively. CONCLUSION The translucency of the zirconia was affected by the coloring procedure and the grain size. Although monolithic zirconia may not be the best esthetic material for the anterior region, it may serve as an alternative in the posterior region for the bilayered zirconia restorations. PMID:27350851

  7. Enhanced structural stability of nanoporous zirconia under irradiation of He

    SciTech Connect

    Yang, Tengfei; Huang, Xuejun; Wang, Chenxu; Zhang, Yanwen; Xue, Jianming; Yan, Sha; Wang, Yuguang

    2012-01-01

    This work reports a greatly enhanced tolerance for He irradiation-induced swelling in nanocrystalline zirconia film with interconnected nanoporous structure (hereinafter referred as to NC-C). Compared to bulk yttria-stabilized zirconia (YSZ) and another nanocrystalline zirconia film only with discrete nano voids (hereinafter referred as to NC-V), the NC-C film reveals good tolerance for irradiation of high-fluence He. No appreciable surface blistering can be found even at the highest fluence of 6 1017 cm2 in NCC film. From TEM analysis of as-irradiated samples, the enhanced tolerance for volume swelling in NCC film is attributed to the enhanced diffusion mechanism of deposited He via widely distributed nano channels. Furthermore, the growth of grain size is quite small for both nanocrystalline zirconia films after irradiation, which is ascribed to the decreasing of area of grain boundary due to loose structure and low energy of primary knock-on atoms for He ions.

  8. Effect of Different Surface Treatments on Repair Micro-shear Bond Strength of Silica- and Zirconia-filled Composite Resins

    PubMed Central

    Joulaei, Mohammad; Bahari, Mahmoud; Ahmadi, Anahid; Savadi Oskoee, Siavash

    2012-01-01

    Background and aims Effect of surface treatments on repair bond strength of aged composite resins might be different due to their dissimilar fillers. The aim was to evaluate the effect of different surface treatments on repair micro-shear bond strength (µSBS) of silica- (Spectrum TPH) and zirconia-filled (Filtek Z250) composite resins. Materials and methods Twenty-seven composite resin blocks were made from each type of composite resin: Z250 and Spectrum TPH. After aging, blocks of each type were randomly divided into three groups according to surface treatments: alloy primer, silane, and only surface roughening. Subsequently, each group was further subdivided into 3 subgroups based on the adhesive system used: Single Bond, Clearfil SE Bond, and Margin Bond. Four composite resin columns were added on each block. After thermocycling, µSBStest were done at cross head speed of 0.5 mm/min. Data was analysed using multifactor ANOVA, one-way ANOVA and a post-hoc Bonferroni tests (α = 0.05). Results Analysis of data showed that the effect of composite resin type was not significant (p > 0.05), but the effects of the type of surface treatment (p = 0.01) and the type of adhesive system (p = 0.01) were significant on repair µSBS. In addition, the cumulative effect of the composite type-surface treatment and the composite type with the type of adhesive system were not statistically significant (p > 0.05). However, the cumulative effects of the adhesive system-surface treatment (p = 0.03) and the composite type-the adhesive system-surface treatments (p = 0.002) were significant. Conclusion Although repair µSBS values of both silica- and zirconia-filled composite resins were similar, use of different combinations of surface treatments and adhesive systems affected their repair µSBS differently. PMID:23277859

  9. Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes.

    PubMed

    Alao, Abdur-Rasheed; Stoll, Richard; Song, Xiao-Fei; Miyazaki, Takashi; Hotta, Yasuhiro; Shibata, Yo; Yin, Ling

    2017-01-01

    This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (Ra) and maximum roughness (Rz) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p>0.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p>0.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving Ra=0.21±0.03µm and Rz=1.73±0.04µm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality.

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

    PubMed

    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

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

    PubMed

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

    2016-01-01

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

  12. A sol-powder coating technique for fabrication of yttria stabilised zirconia

    SciTech Connect

    Wattanasiriwech, Darunee . E-mail: darunee@mfu.ac.th; Wattanasiriwech, Suthee; Stevens, Ron

    2006-08-10

    Yttria stabilised zirconia has been prepared using a simple sol-powder coating technique. The polymeric yttria sol, which was prepared using 1,3 propanediol as a network modifier, was homogeneously mixed with nanocrystalline zirconia powder and it showed a dual function: as a binder which promoted densification and a phase modifier which stabilised zirconia in the tetragonal and cubic phases. Thermal analysis and X-ray diffraction revealed that the polymeric yttria sol which decomposed at low temperature into yttrium oxide could change the m {sup {yields}} t phase transformation behaviour of the zirconia, possibly due to the small particle size and very high surface area of both yttria and zirconia particles allowing rapid alloying. The sintered samples exhibited three crystalline phases: monoclinic, tetragonal and cubic, in which cubic and tetragonal are the major phases. The weight fractions of the individual phases present in the selected specimens were determined using quantitative Rietveld analysis.

  13. Synthesis and surface characterization of alumina-silica-zirconia nanocomposite ceramic fibres on aluminium at room temperature

    NASA Astrophysics Data System (ADS)

    Mubarak Ali, M.; Raj, V.

    2010-04-01

    Alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres were synthesized by conventional anodization route. Scanning Electron Microscopy (SEM), Atomic Force microscopy (AFM), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray spectroscopy (EDAX) were used to characterize the morphology and crystalloid structure of ASZNC fibres. Current density (DC) is one of the important parameters to get the alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres by this route. Annealing of the films exhibited a drastic change in the properties due to improved crystallinity. The root mean square roughness of the sample observed from atomic force microscopic analysis is about 71.5 nm which is comparable to the average grain size of the coatings which is about 72 nm obtained from X-Ray diffraction. The results indicate that, the ASZNC fibres are arranged well in the nanostructure. The thickness of the coating increased with the anodizing time, but the coatings turned rougher and more porous. At the initial stage the growth of ceramic coating increases inwards to the metal substrate and outwards to the coating surface simultaneously. Subsequently, it mainly grows towards the metal substrate and the density of the ceramic coating increases gradually, which results in the decrease of the total thickness as anodizing time increases. This new approach of preparing ASZNC ceramic fibres may be important in applications ranging from gas sensors to various engineering materials.

  14. Study of the catalysis and surface chemistry occurring at nickel/zirconia anodes in solid oxide fuel cells running on natural gas

    NASA Astrophysics Data System (ADS)

    Finnerty, C. M.; Cunningham, R. H.; Ormerod, R. M.

    Nickel-based/yttria-stabilised zirconia anodes for solid oxide fuel cells (SOFCs) running on natural gas have been developed which show increased resistance towards carbon deposition and improved durability. Surface carbon formed on the anodes during reforming has been characterised using temperature programmed oxidation (TPO). The influence of anode composition and formulation, pre-treatment method, operating temperature and methane/steam ratio have been studied. Doping the nickel/zirconia anode with small quantities of molybdenum leads to a substantial reduction in the amount of carbon deposited. As current is drawn from the SOFC increased methane conversion occurs together with reduced carbon deposition.

  15. Influence of Surface Conditioning Protocols on Reparability of CAD/CAM Zirconia-reinforced Lithium Silicate Ceramic.

    PubMed

    Al-Thagafi, Rana; Al-Zordk, Walid; Saker, Samah

    2016-01-01

    To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic. Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric EvoCeram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p < 0.05). The highest microtensile repair bond strength for Vita Suprinity was reported in group CO (33.1 ± 2.4 MPa) and the lowest in group HF (27.4 ± 4.4 MPa). Regarding IPS e.max CAD, group CO showed the highest (30.5 ± 4.9 MPa) and HF the lowest microtensile bond strength (22.4 ± 5.7 MPa). Groups HF, HF-H, and CO showed statistically significant differences in terms of all ceramic types used (p < 0.05). The control group showed exclusively adhesive failures, while in HF, HF-H, and CO groups, mixed failures were predominant. Repair bond strength to zirconia-reinforced lithium silicate

  16. Influence of starting precursors and synthesis methods on the physiochemical properties of zirconia

    SciTech Connect

    Gaydhankar, T.R.; Jha, R.K.; Nikalje, M.D.; Waghmare, K.J.

    2014-07-01

    Graphical abstract: Crystallite size of tetragonal phase of the zirconia samples prepared using different synthesis parameters and precursors as a function of calcination temperature. Surface area values of the zirconia samples calcined at 500 and 700 °C are in given brackets. - Highlights: • Zirconia prepared with modified sol–gel method is less stable compared with zirconia prepared by precipitation method. • Optimized synthesis conditions shifted the glow exotherm to higher temperature range indicating better thermal stability. • Tetragonal-zirconia could be synthesized in cost-effective manner using zirconium oxy-nitrate. • In our studies no co-relation between the surface area and crystallite size was observed. - Abstract: Under identical and judiciously pre-optimized synthesis conditions, the influence of different combinations of zirconium sources and/or post treatment conditions on structural properties, thermal stability, phase composition and morphology of zirconia has been investigated. High surface area tetragonal zirconia could be synthesized in a cost-effective manner from 1 M solution of zirconium oxy-nitrate at pH 11 using aqueous ammonia solution as a precipitant when calcined at 400 °C for 3 h. Irrespective of the preparation method, pH and starting precursor, zirconia samples prepared without digestion contained dominant monoclinic phase with some traces of tetragonal phase when calcined at 700 °C. Even though there is linear decrease in surface area with increase in the crystallite size for each sample as a function of calcination temperature, no co-relation between the surface area and crystallite size could be achieved. SEM images show agglomerated and irregular shape particles between 10 to 20 μm.

  17. The wetting characteristics and surface tension of some Ni-based alloys on yttria, hafnia, alumina, and zirconia substrates

    NASA Technical Reports Server (NTRS)

    Kanetkar, C. S.; Kacar, A. S.; Stefanescu, D. M.

    1988-01-01

    The surface tension and wetting characteristics of four commercial Ni-based alloys (UD718, Waspaloy, UD720, and UD520), pure Ni, and three special alloys (Ni-20 percent Cr, Ni-20 percent Cr-1 percent Al, and Ni-20 percent Cr-4 percent Al) on various ceramic substrates (including alumina, zirconia, hafnia, and yttria) were investigated using sessile drop experiments. Most of the systems studied exhibited a nonwetting behavior. Wetting improved with holding time at a given temperature to the point that some systems, such as Ni-20Cr on alumina, Ni-20Cr-4Al on alumina and on yttria, became marginally wetting. Wetting characteristics were apparently related to constitutional undercooling, which in turn could be affected by the metal dissolving some of the substrate during measurements.

  18. Silica coating of zirconia by silicon nitride hydrolysis on adhesion promotion of resin to zirconia.

    PubMed

    Lung, Christie Ying Kei; Liu, Dan; Matinlinna, Jukka Pekka

    2015-01-01

    In this study, the effect of silica coating on zirconia by silicon nitride hydrolysis in resin zirconia bonding was investigated. The silica coated zirconia samples were prepared in silicon nitride dispersion at 90 °C under different immersion times followed by a thermal treatment at 1400 °C. Four test groups were prepared: 1) zirconia samples treated by sandblasting, 2) zirconia samples treated by immersion in silicon nitride dispersion for 6 h, 3) zirconia samples treated by immersion in silicon nitride dispersion for 24 h and 4) zirconia samples treated by immersion in silicon nitride dispersion for 48 h. The coatings were characterized by SEM, EDX, XRD and Raman. The resin zirconia bond strengths of the four test groups were evaluated under three storage conditions: dry storage, water storage in deionized water at 37 °C for 30 days and thermo-cycling for 6000 cycles between 5.0 and 55.0 °C. Surface morphology and composition of zirconia were changed after surface treatments. Phase transformation was observed for zirconia surface by sandblasting treatment but was not observed for zirconia surface treated with silicon nitride hydrolysis. Significant differences in bond strengths were found under different surface treatments (p<0.001) and under three storage conditions (p<0.005). The highest bond strength values were obtained by sandblasting treatment.

  19. Ab initio atomistic thermodynamics study on the sulfur tolerance mechanism of the oxygen-enriched yttria-stabilized zirconia surface

    NASA Astrophysics Data System (ADS)

    Chu, Xingli; Zhang, Yanxing; Li, Shasha; Yang, Zongxian

    2014-04-01

    The first-principles method based on density functional theory (DFT) is used to investigate the reaction mechanism for the adsorption of H2S on the oxygen-enriched yttria-stabilized zirconia (YSZ + O) (111) surface. It is found that the H2S dissociation processes have low energy barriers (< 0.5 eV) and high exothermicities (2.5 eV), and the dissociative S atoms may result in the poisoning of the YSZ + O surface by forming the SO and the hyposulfite (SO22 -) species with very strong bonds to the surface. In addition, using the ab initio atomistic thermodynamics method, the surface regeneration or de-sulfurization process of a sulfur-poisoned (i.e. sulfur-covered) YSZ + O(111) surface is studied. According to the phase diagram, the adsorbed atomic sulfur can be oxidized to SO2 and removed from the YSZ + O surface by introducing oxidizing reagents, e.g. O2 and H2O.

  20. Effect of various surface preparations on bond strength of a gingiva-colored indirect composite to zirconia framework for implant-supported prostheses.

    PubMed

    Komine, Futoshi; Koizuka, Mai; Fushiki, Ryosuke; Iwasaki, Taro; Kubochi, Kei; Matsumura, Hideo

    2015-01-01

    To evaluate the effects of various surface preparations on shear bond strength of a gingiva-colored indirect composite material and zirconia framework. Zirconia disks were prepared with one of nine surface treatments: hydrofluoric acid etching (HF), heating at 1,000°C for 10 min (HT), wet-grinding with 600- and 1500-grit SiC paper (SiC 600 and 1500), alumina-blasting at 0.1, 0.2, 0.4 and 0.6 MPa (AB 0.1, 0.2, 0.4, and 0.6), and no treatment (NT). An indirect composite material was bonded to zirconia. Shear bond strengths were measured. Bond strength was significantly higher in AB 0.2, 0.4, and 0.6 groups than in other groups at 0 and 20,000 thermocycles. Post-thermocycling bond strength was lower in NT, HF, and HT groups than in other groups. Alumina-blasting with 0.2 MPa or higher yielded sufficient durable bond strength between gingiva-colored indirect composite and zirconia frameworks. Hydrofluoric acid etching and heat treatment did not achieve durable bond strengths.

  1. Conformal nanocoating of zirconia nanoparticles by atomic layer deposition in a fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Hakim, Luis F.; George, Steven M.; Weimer, Alan W.

    2005-07-01

    Primary zirconia nanoparticles were conformally coated with alumina ultrathin films using atomic layer deposition (ALD) in a fluidized bed reactor. Alternating doses of trimethylaluminium and water vapour were performed to deposit Al2O3 nanolayers on the surface of 26 nm zirconia nanoparticles. Transmission Fourier transform infrared spectroscopy was performed ex situ. Bulk Al2O3 vibrational modes were observed for coated particles after 50 and 70 cycles. Coated nanoparticles were also examined with transmission electron microscopy, high-resolution field emission scanning electron microscopy and energy dispersive spectroscopy. Analysis revealed highly conformal and uniform alumina nanofilms throughout the surface of zirconia nanoparticles. The particle size distribution and surface area of the nanoparticles are not affected by the coating process. Primary nanoparticles are coated individually despite their high aggregation tendency during fluidization. The dynamic aggregation behaviour of zirconia nanoparticles in the fluidized bed plays a key role in the individual coating of nanoparticles.

  2. Conformal nanocoating of zirconia nanoparticles by atomic layer deposition in a fluidized bed reactor.

    PubMed

    Hakim, Luis F; George, Steven M; Weimer, Alan W

    2005-07-01

    Primary zirconia nanoparticles were conformally coated with alumina ultrathin films using atomic layer deposition (ALD) in a fluidized bed reactor. Alternating doses of trimethylaluminium and water vapour were performed to deposit Al(2)O(3) nanolayers on the surface of 26 nm zirconia nanoparticles. Transmission Fourier transform infrared spectroscopy was performed ex situ. Bulk Al(2)O(3) vibrational modes were observed for coated particles after 50 and 70 cycles. Coated nanoparticles were also examined with transmission electron microscopy, high-resolution field emission scanning electron microscopy and energy dispersive spectroscopy. Analysis revealed highly conformal and uniform alumina nanofilms throughout the surface of zirconia nanoparticles. The particle size distribution and surface area of the nanoparticles are not affected by the coating process. Primary nanoparticles are coated individually despite their high aggregation tendency during fluidization. The dynamic aggregation behaviour of zirconia nanoparticles in the fluidized bed plays a key role in the individual coating of nanoparticles.

  3. Dependence of the Electron Beam Energy and Types of Surface to Determine EBSD Indexing Reliability in Yttria-Stabilized Zirconia

    SciTech Connect

    Saraf, Laxmikant V.

    2012-04-01

    Electron backscatter diffraction (EBSD) is a powerful technique for the surface microstructure analysis. EBSD analysis of cubic yttria-stabilized zirconia (YSZ) in two and three dimensions (2-D, 3-D) is demonstrated using sequential slicing from a focused ion beam (FIB) followed by EBSD mapping to represent 3-D reconstructed high density grain structure with random orientation. The statistics related to accuracy of EBSD band detection shows that probability of accurate grain orientation detection increased significantly when the electron beam energy is increased from 10 kV to 30 kV. As a result of better sampling with increased interaction volume, a disparity between local and average grain orientation angle also exhibited the dependence of the electron beam energy to determine the accuracy of grain orientation. To study the accuracy and quality of EBSD band detection as a function of surface roughness and over layer formation, rapid EBSD measurement tests are performed on (a) YSZ surfaces ion-polished at ion beam energies of 65 nA at 30 kV and 1 nA at 30 kV and (b) carbon coated versus uncoated YSZ surfaces. The EBSD results at both 10 kV and 30 kV electron beam energies indicate that EBSD band detection accuracy is negatively affected by surface roughness and amorphous over layer formation.

  4. Influence of cyclic loading on the adhesive effectiveness of resin-zirconia interface after femtosecond laser irradiation and conventional surface treatments.

    PubMed

    Vicente, María; Gomes, Ana L; Montero, Javier; Rosel, Eva; Seoane, Vicente; Albaladejo, Alberto

    2016-01-01

    The aim of this study was to evaluate the influence of cyclic loading on the shear bond strength (SBS) of a self-adhesive resin cement to zirconia surfaces after femtosecond laser irradiation at different steps and several conventional surface treatments. One hundred fifty square-shaped zirconia samples were divided into five groups according their surface treatment: NT Group-no surface treatment; APA25 Group-airborne abrasion with 25 μm alumina particles; TSC Group-tribochemical silica coating; FS20 Group-femtosecond laser irradiation (800 nm, 4 mJ, 40 fs/pulse, 1 kHz, step 20); and FS40 Group-femtosecond laser irradiation (same parameters except step 40). Self-adhesive resin cement cylinders were bonded at the centre of the zirconia surface. For each experimental group, half of the specimens were subject to cyclic loading under 90 N (50.000 cycles, 3 cycles/sec) and the rest of the specimens were stored in distilled water at 37°C. All subgroups were tested for SBS with a universal testing machine at a crosshead speed of 0.5 mm/min, until fracture. The results were analyzed statistically. When cyclic loading was applied, all surface treatments had lower SBS values, except APA25. The four surface treatments had the same SBS values when cyclic loading was employed. Use of femtosecond laser irradiation could be an alternative to conventional surface treatments to achieve suitable adhesion zirconia and resin cements. Femtosecond laser irradiation at step 40 is preferable because it is more efficient and faster. © 2016 Wiley Periodicals, Inc.

  5. A facile approach to the synthesis of non-porous and microporous sub-micron spherical zirconia and alumina-zirconia solid solution.

    PubMed

    Ghotbi, Mohammad Yeganeh; Nasiri, Vida; Rafiee, Mehdi

    2013-01-01

    Amorphous monodisperse sub-micron spherical zirconia and alumina/zirconia solid solution particles were prepared by hydrolysis of zirconium and aluminum salts in ethanol. The heat-treatment process of the amorphous materials in air atmosphere at 500°C for 2h leaded to the production of non-porous zirconia and alumina/zirconia solid solution in tetragonal phase. The alkaline etching process of the as-prepared alumina/zirconia solid solution resulted in the formation of mono-modal microporous material with specific surface area of 125.0 m(2) g(-1) in comparison with 2. 9m(2) g(-1) for the parent material. Thermal analysis of the solid solution revealed that the incorporation of aluminum ions in the zirconia structure has decreased the phase transformation temperature from amorphous to crystalline structure. Moreover, optical study confirmed the presence of oxygen vacancy defect by substitution of tetravalent cations, Zr(4+) by trivalent cations, Al(3+) in zirconia lattice.

  6. Surface and Mechanical Characterization of Dental Yttria-Stabilized Tetragonal Zirconia Polycrystals (3Y-TZP) After Different Aging Processes.

    PubMed

    Pinto, Palena A; Colas, Guillaume; Filleter, Tobin; De Souza, Grace M

    2016-12-01

    Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is a ceramic material used in indirect dental restorations. However, phase transformation at body temperature may compromise the material's mechanical properties, affecting the clinical performance of the restoration. The effect of mastication on 3Y-TZP aging has not been investigated. 3Y-TZP specimens (IPS E-max ZirCAD and Z5) were aged in three different modes (n=13): no aging (control), hydrothermal aging (HA), or chewing simulation (CS). Mechanical properties and surface topography were analyzed. Analysis of variance showed that neither aging protocol (p=0.692) nor material (p=0.283) or the interaction between them (p=0.216) had a significant effect on flexural strength, values ranged from 928.8 MPa (IPSHA) to 1,080.6 MPa (Z5HA). Nanoindentation analysis showed that material, aging protocol, and the interaction between them had a significant effect (p<0.001) on surface hardness and reduced Young's modulus. The compositional analysis revealed similar yttrium content for all the experimental conditions (aging: p=0.997; material: p=0.248; interaction material×aging: p=0.720). Atomic force microscopy showed an effect of aging protocols on phase transformation, with samples submitted to CS exhibiting features compatible with maximized phase transformation, such as increased volume of the material microstructure at the surface leading to an increase in surface roughness.

  7. Dependence of the electron beam energy and types of surface to determine EBSD indexing reliability in yttria-stabilized zirconia.

    PubMed

    Saraf, Laxmikant V

    2012-04-01

    Electron backscatter diffraction (EBSD) is a powerful technique for surface microstructure analysis. EBSD analysis of cubic yttria-stabilized zirconia (YSZ) is demonstrated. The statistics related to EBSD indexing reliability shows that the probability of accurate grain orientation detection increased significantly when the electron beam energy was increased from 10 to 30 kV. As a result of better sampling with increased interaction volume, a disparity between local and average grain misorientation angle also exhibited the dependence of the electron beam energy to determine the accuracy of grain orientation. To study EBSD indexing reliability as a function of surface roughness and overlayer formation, rapid EBSD measurement tests were performed on (a) YSZ surfaces ion-polished at ion beam energies of 65 nA at 30 kV and 1 nA at 30 kV and (b) carbon-coated versus uncoated YSZ surfaces. The EBSD results at both 10 and 30 kV electron beam energies indicate that EBSD indexing reliability is negatively affected by higher ion beam milling current and amorphous overlayer formation.

  8. Performance of zirconia abutments for implant-supported single-tooth crowns in esthetic areas: a retrospective study up to 12-year follow-up.

    PubMed

    Passos, Sheila Pestana; Linke, Bernie; Larjava, Hannu; French, David

    2016-01-01

    The aim of this clinical study was to assess complications, success, and survival rates of zirconia abutments from different implant designs. Anterior implant-supported single-tooth restorations, after 1-12 years of clinical function, were evaluated. One hundred and fifty-eight zirconia implant abutments placed in 141 patients were evaluated. Mechanical complications were observed, such as presence or absence of abutment fractures and loss of retention. In addition, the peri-implant parameters were observed. Statistical analysis was performed using Fisher's exact tests, and bone level was analyzed using the nonparametric Mann-Whitney U-test for non-normally distributed data. Sixteen restorations exhibited different complications. However, no significant difference was observed between the standard and platform switching. The standard platforms exhibited higher marginal bone loss than platform switching design followed up to 5 years. Platform switching has a potentially higher risk of fracture in some designs. In our study, one standard platform as well as two-platform switch designs seem to withstand fracture in the anterior area, regardless of the implant width. Survival and success rates were 93.8% and 81.2% (up to >7 years ≤12), respectively, for standard platform; and 90 and 84% (up to >2 years ≤5), respectively, for platform switching. In general, standard platform implants restored with zirconia abutments were successful for the longest periods of observation and are a viable treatment alternative in anterior areas. Some of the studied designs of platform switching implants with zirconia abutments performed well for up to 5 years. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Gelcast zirconia-alumina composites

    SciTech Connect

    Omatete, O.O.; Bleier, A.; Westmoreland, C.G.; Young, A.C.

    1991-01-01

    Near net-shaped parts of zirconia-alumina composites have been successfully formed by gelcasting, a technique which utilizes in situ polymerization of acrylamide monomers. The high solids loading required for gelcasting ({approximately}50 vol %) was obtained by controlling the pH-dependent stability of the aqueous zirconia-alumina suspensions. A strong correspondence was found among the surface charges on the particles, colloidal stability, and the maximum solids loading. 14 refs., 3 figs., 2 tabs.

  10. Preliminary studies on the effects of in situ synthesized polycrystalline particulates on the bonding strength of resin to zirconia ceramic surface

    NASA Astrophysics Data System (ADS)

    Tian, Yueming; Zhang, Lingling; Zhang, Zutai; Ding, Ning; Liu, Yan; Tian, Guozhong

    2015-12-01

    To develop a novel zirconia surface modification method to improve the shear bond strength of resin cement. Yttrium-stabilized tetragonal zirconia (Y-TZP) discs were cut from prefabricated ceramic blocks and polished through 1200-grit SiC abrasive. Based on the immersion time of zirconia disc in HF solution, zirconia samples were divided into four groups. Then, put samples to CaCl2 solution, dipped in NaOH solution from 20 °C to 80 °C in a water bath, kept at 80 °C for 2 h. After final sintering, surface appearance and chemical components were characterized with scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD), respectively. The surface roughness of discs was measured as well. Shear bond strength of zirconia to resin cement was tested and the failure mode was analyzed. Three point bending tests were done to determine the flexural strength of samples. The statistical analysis was also done for all above data. ZrO2 polycrystalline particulates were in situ synthesized on the surface of zirconia substrates. The Ra values of the four groups were 0.27 ± 0.05 μm, 0.89 ± 0.34 μm, 1.04 ± 0.41 μm and 1.41 ± 0.38 μm, respectively. The treated group was statistically significant different from the control group (p < 0.05). Shear bond strength values of the four groups were 7.88 ± 1.94 MPa, 11.87 ± 3.7 MPa, 17.84 ± 6.21 MPa and 16.27 ± 5.87 MPa, respectively, and those of I5 and I7 were statistically different from that of C (p < 0.05). The failure mode was mainly adhesive in group C and mixed in I5. Three point bending strength values of the four groups were 730.21 ± 56.91 MPa, 689.81 ± 73.75 MPa, 704.25 ± 91.44 MPa and 702.28 ± 86.05 MPa, respectively, without statistically significant difference between each other (p > 0.05). In the conclusion, in situ synthesized polycrystalline particulates on zirconium ceramic surface can effectively improve the bonding strength of resin, avoid micro cracks and

  11. Textural and structural properties and surface acidity characterization of mesoporous silica-zirconia molecular sieves

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellón, E.; Jiménez-López, A.; Maireles-Torres, P.; Jones, D. J.; Rozière, J.; Trombetta, M.; Busca, G.; Lenarda, M.; Storaro, L.

    2003-11-01

    Homogeneous mesoporous zirconium-containing MCM-41 type silica were prepared by supramolecular templating and their textural and structural properties were studied using powder X-ray diffraction, N 2 porosimetry, atomic force microscopy, EXAFS, XPS, and UV-VIS-NIR diffuse reflectance spectroscopy. Their acid properties were also studied by using IR spectroscopy and by the use of catalytic tests such as the decomposition of isopropanol and the isomerization of 1-butene. The materials prepared show a good degree of crystallinity with a regular ordering of the pores into a hexagonal arrangement and high thermal stability. The specific surface area of the prepared materials decreases as the zirconium content rises. Zirconium atoms are in coordination 7 to 8 and located at the surface of the pores such that a high proportion of the oxygen atoms bonded to zirconium corresponds to surface non-condensed oxygen atoms. Both facts are responsible for the acid properties of the solids that show weak Brønsted and medium strong Lewis acidity.

  12. Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

    NASA Astrophysics Data System (ADS)

    Zhu, J. W.; Yang, D. W.

    2007-07-01

    In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

  13. Proliferation and osteogenic differentiation of human mesenchymal stem cells on zirconia and titanium with different surface topography.

    PubMed

    Hirano, Tomoki; Sasaki, Hodaka; Honma, Shinya; Furuya, Yoshitaka; Miura, Tadashi; Yajima, Yasutomo; Yoshinari, Masao

    2015-01-01

    The purpose of this study was to elucidate behavior of human mesenchymal stem cells (hMSCs) on yttria stabilized tetragonal zirconia polycrystals (TZP) and commercial pure titanium (CpTi) with different surface topography. Mirror-polished (MS), sandblasted with 150-μm alumina (SB150) and SB150 acid-etched (SB150E) were prepared on TZP and CpTi. Proliferation, osteogenic differentiation of hMSCs was evaluated. The scanning electron microscopy showed that micro- and nano-topographies were created on both TZP and CpTi SB150E surfaces. The proliferation ability, ALP activity, expression of Runx2 on the both SB150E specimens was significantly higher than those on the other specimens. These results suggested that creation of micro- and nano-topographies on TZP and CpTi by blast and acid-etching may offer a promising method for enhancing the proliferation and differentiation of hMSCs in clinical application.

  14. Investigation of the oxygen exchange mechanism on Pt|yttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path

    PubMed Central

    Opitz, Alexander K.; Lutz, Alexander; Kubicek, Markus; Kubel, Frank; Hutter, Herbert; Fleig, Jürgen

    2011-01-01

    The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550–700 °C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300–400 °C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded. The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum – most likely along Pt grain boundaries – as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum. PMID:22210951

  15. Investigation of the oxygen exchange mechanism on Pt|yttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path.

    PubMed

    Opitz, Alexander K; Lutz, Alexander; Kubicek, Markus; Kubel, Frank; Hutter, Herbert; Fleig, Jürgen

    2011-11-30

    The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550-700 °C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300-400 °C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded.The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum - most likely along Pt grain boundaries - as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum.

  16. Determination of retinal surface area.

    PubMed

    Nagra, Manbir; Gilmartin, Bernard; Thai, Ngoc Jade; Logan, Nicola S

    2017-09-01

    Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm(2) , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P < 0.01) which, contrasted with ST (365 ± 43 mm(2) ), was significant for IT (340 ± 40 mm(2) P < 0.01), SN (337 ± 40 mm(2) P < 0.01) and IN (321 ± 39 mm(2) P < 0.01) quadrants. For all quadrants, QRSA was significantly correlated with AL (P < 0.01) and

  17. Effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading.

    PubMed

    Ozcan, Mutlu; Melo, Renata M; Souza, Rodrigo O A; Machado, João P B; Felipe Valandro, Luiz; Botttino, Marco A

    2013-04-01

    This study evaluated the effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading. Disc-shaped zirconia specimens (Ø: 15mm, thickness: 1.2mm) (N=32) were submitted to one of the air-particle abrasion protocols (n=8 per group): (a) 50μm Al2O3 particles, (b) 110μm Al2O3 particles coated with silica (Rocatec Plus), (c) 30μm Al2O3 particles coated with silica (CoJet Sand) for 20s at 2.8bar pressure. Control group received no air-abrasion. All specimens were initially cyclic loaded (×20,000, 50N, 1Hz) in water at 37°C and then subjected to biaxial flexural strength testing where the conditioned surface was under tension. Zirconia surfaces were characterized and roughness was measured with 3D surface profilometer. Phase transformation from tetragonal to monoclinic was determined by Raman spectroscopy. The relative amount of transformed monoclinic zirconia (FM) and transformed zone depth (TZD) were measured using XRD. The data (MPa) were analyzed using ANOVA, Tukey's tests and Weibull modulus (m) were calculated for each group (95% CI). The biaxial flexural strength (MPa) of CoJet treated group (1266.3±158(A)) was not significantly different than that of Rocatec Plus group (1179±216.4(A,B)) but was significantly higher than the other groups (Control: 942.3±74.6(C); 50μm Al2O3: 915.2±185.7(B,C)). Weibull modulus was higher for control (m=13.79) than those of other groups (m=4.95, m=5.64, m=9.13 for group a, b and c, respectively). Surface roughness (Ra) was the highest with 50μm Al2O3 (0.261μm) than those of other groups (0.15-0.195μm). After all air-abrasion protocols, FM increased (15.02%-19.25%) compared to control group (11.12%). TZD also showed increase after air-abrasion protocols (0.83-1.07μm) compared to control group (0.59μm). Air-abrasion protocols increased the roughness and monoclinic phase but in turn abrasion with 30μm Al2O3 particles coated

  18. Bacterial adhesion and biofilm formation on yttria-stabilized, tetragonal zirconia and titanium oral implant materials with low surface roughness - an in situ study.

    PubMed

    Al-Ahmad, Ali; Karygianni, Lamprini; Schulze Wartenhorst, Max; Bächle, Maria; Hellwig, Elmar; Follo, Marie; Vach, Kirstin; Han, Jung-Suk

    2016-04-19

    Bacterially-driven mucosal inflammation and the development of periimplantitis can lead to oral implant failure. In this study, initial bacterial adhesion after 2 h and biofilm formation after 1 day and 3 days were analyzed in situ on novel 3 mol% yttria-stabilized tetragonal zirconia polycrystal samples (Zr; 3Y-TZP), as well as on alumina and niobium co-doped yttria-stabilized tetragonal zirconia samples (Al-Zr; Al2O3/Y(Nb)-TZP). Pure titanium implant material (Ti) and bovine enamel slabs (BES) served as controls. The initially adherent oral bacteria were determined by DAPI-staining. Biofilm thickness, surface covering grade and content of oral streptococci within the biofilm were measured by fluorescence in situ hybridization. No significant differences between the ceramic and titanium surfaces were detectable for either initial bacterial adhesion or the oral streptococci content of the in situ biofilm. The values of oral biofilm thickness on the implant surfaces were almost doubled after three days compared to the first day of oral exposure. Nevertheless, the biofilm thickness values among the different implant surfaces and controls did not differ significantly for any time point of measurement after 1 day or 3 days of biofilm formation. Significant differences in the covering grade were only detected between day 1 and day 3 for each tested implant material group. The content of oral streptococci increased significantly in parallel with the increase of biofilm age from day 1 to day 3. In conclusion, oral implant zirconia surfaces with low surface roughness are comparable to titanium surfaces with regard to initial bacterial adhesion and biofilm formation.

  19. Effect of different surface treatments on adhesion of In-Ceram Zirconia to enamel and dentin substrates.

    PubMed

    Saker, Samah; Ibrahim, Fatma; Ozcan, Mutlu

    2013-08-01

    Resin bonding of In-Ceram Zirconia (ICZ) ceramics is still a challenge, especially for minimally invasive applications. This study evaluated the adhesion of ICZ to enamel and dentin after different surface treatments of the ceramic. ICZ ceramic specimens (diameter: 6 mm; thickness: 2 mm) (N = 100) were fabricated following the manufacturer's instructions and randomly assigned to 5 groups (n = 20), according to the surface treatment methods applied. The groups were as follows: group C: no treatment; group SB: sandblasting; group SCS-S: CoJet+silane; group SCS-P: CoJet+Alloy Primer; group GE-S: glaze+ hydrofluoric acid etching (9.6%) for 60 s+silane. Each group was randomly divided into two subgroups to be bonded to either enamel or dentin (n = 10 per group) using MDP-based resin cement (Panavia F2.0). All the specimens were subjected to thermocycling (5000x, 5°C-55°C). The specimens were mounted in a universal testing machine and tensile force was applied to the ceramic/cement interface until failure occurred (1 mm/min). After evaluating all the debonded specimens under SEM, the failure types were defined as either "adhesive" with no cement left on the ceramic surface (score 0) or "mixed" with less than 1/2 of the cement left adhered to the surface with no cohesive failure of the substrate (score 1). The data were statistically evaluated using 2-way ANOVA and Tukey's tests (α = 0.05). The highest tensile bond strength for the enamel surfaces was obtained in group GE-S (18.1 ± 2 MPa) and the lowest in group SB (7.1 ± 1.4 MPa). Regarding dentin, group CSC-P showed the highest (12 ± 1.3 MPa) and SB the lowest tensile bond strength (5.7 ± 0.4 MPa). Groups SB, CSC-S, CSC-P, and GE-S did not show significant differences between the different surface treatments on either enamel or dentin surfaces (p < 0.05, p < 0.001, respectively). Groups CSC-P and GE-S presented similar bond strength for both the enamel and dentin substrates (p < 0.8 and p < 0.9), respectively

  20. Evaluation of self-adhesive resin cement bond strength to yttria-stabilized zirconia ceramic (Y-TZP) using four surface treatments.

    PubMed

    Miragaya, Luciana; Maia, Luciane Cople; Sabrosa, Carlos Eduardo; de Goes, Mário Fernando; da Silva, Eduardo Moreira

    2011-10-01

    To evaluate the influence of four surface treatments on the bond strength of a self-adhesive resin cement to an yttria-stabilized zirconia (Y-TZP) ceramic material (Lava Frame zirconia). Forty plates (8 x 6 x 1 mm) of a Y-TZP ceramic restorative material were randomly assigned to four groups (n = 10) according to the surface treatments: control, no treatment; airborne-particle abrasion with 50-μm Al2O3; coating with an MDP-based primer; conditioning with Rocatec System. The ceramic plates treated with each of the four methods were further divided into 2 subgroups according to the resin cement tested: RelyXTM ARC (ARC, conventional) and RelyXTM Unicem (Ucem, self-adhesive). The resin cements were put into PVC tubes (diameter 0.75 mm, 0.5 mm height) placed on the ceramic plate surfaces. After water storage at 37°C for 24 h, the specimens were submitted to a microshear bond strength (μSBS) test at a crosshead speed of 1.0 mm/min. The surface treatments significantly influenced the μSBS (p < 0.05). For the four surface treatments, UCem presented significantly higher μSBS than ARC (p < 0.05). For both resin cements, the best result was produced by the MDP-based primer: ARC 15.9 ± 5.0 MPa and UCem 36.2 ± 2.1 MPa. The highest μSBS values were presented by UCem on ceramic plates treated with the MDP-based primer (36.2 ± 2.1 MPa) and Rocatec system (37.4 ± 2.3 MPa). Irrespective of the surface treatment, the self-adhesive resin cement performed better in terms of bond strength to yttria-stabilized zirconia ceramic than did conventional resin cement.

  1. Evaluation of resin bond strength to yttria-stabilized tetragonal zirconia and framework marginal fit: comparison of different surface conditionings.

    PubMed

    Vanderlei, A; Bottino, M A; Valandro, L F

    2014-01-01

    The purpose of this study was to evaluate the effect of different surface treatments of yttria-stabilized tetragonal zirconia (Y-TZP) on bond strength durability and marginal discrepancies. For adhesion testing, 144 specimens of VITA In-Ceram YZ ceramic for InLab were obtained (5.25×3.75×4.5 mm) and divided into six groups (n=24) according to the surface treatment: 1) Control (CRTL): untreated; 2) SIL: tribochemical silica coating (CoJet system, 3M/ESPE AG); 3) V1+HF: spray application of low-fusing porcelain glaze (V1, VITA Akzent Spray Glaze) followed by etching with hydrofluoric acid (HF) (one minute); 4) V1+SIL: V1 glazing (VITA Akzent Spray Glaze) followed by tribochemical silica coating; 5) V2+HF: brush application of low-fusing porcelain glaze (VITA Akzent Glaze) plus etching with HF (one minute); and 6) V2+SIL: V2 glazing (VITA Akzent Glaze) plus tribochemical silica coating. After all treatments, the surfaces were silanized for five minutes (ESPE-SIL) and cementation was performed using Panavia F (Kuraray). Half of the specimens in each treatment were tested 24 hours after cementation (dry), with the other half subjected to storage (150 days) and thermocycling (12,000×) (aging), and then a shear test was carried out (1 mm/min). The micromorphological (digital optical profilometry and scanning electron microscopy) and elemental analyses of the treated surfaces were performed. The inner surfaces of 60 Y-TZP infrastructures were conditioned and marginal fit was evaluated. The statistical analysis revealed that the groups treated via surface glaze application followed by hydrofluoric acid etching and silanization showed the highest bond strength (in dry and aging conditions), but the bond strengths were affected by aging. The highest marginal discrepancies were observed in the groups receiving glaze (117.4 ± 29.6 to 105.8 ± 12.2 μm) when compared to other groups (55.3 ± 8.7 and 55 ± 8.5 μm). Low-fusing porcelain glaze + hydrofluoric acid etching

  2. Enamel wear opposing polished and aged zirconia.

    PubMed

    Burgess, J O; Janyavula, S; Lawson, N C; Lucas, T J; Cakir, D

    2014-01-01

    Aging of dental zirconia roughens its surface through low temperature degradation. We hypothesized that age-related roughening of zirconia crowns may cause detrimental wear to the enamel of an opposing tooth. To test our hypothesis, we subjected artificially aged zirconia and reference specimens to simulated mastication in a wear device and measured the wear of an opposing enamel cusp. Additionally, the roughness of the pretest surfaces was measured. The zirconia specimens, artificially aged by autoclave, showed no significant increase in roughness compared to the nonaged specimens. Furthermore, no significant difference in material or opposing enamel wear between the aged and nonaged zirconia was seen. All zirconia specimens showed less material and opposing enamel wear than the enamel to enamel control or veneering porcelain specimens. Scanning electron micrographs showed relatively smooth surfaces of aged and nonaged zirconia following wear testing. The micrographs of the veneering ceramic showed sharp fractured edges and fragments of wear debris. Zirconia may be considered a wear-friendly material for restorations opposing enamel, even after simulated aging.

  3. Photofunctionalization of dental zirconia oxide: Surface modification to improve bio-integration preserving crystal stability.

    PubMed

    Roy, Marco; Pompella, Alfonso; Kubacki, Jerzy; Piosik, Adam; Psiuk, Bronisław; Klimontko, Joanna; Szade, Jacek; Roy, Robert A; Hedzelek, Wieslaw

    2017-08-01

    The use of zirconium oxide in dental implantology is rapidly increasing as it is regarded as being more aesthetical and biologically friendly than titanium oxide. The interaction of titanium oxide with cells and proteins has proven to be significantly affected by the inevitable atmospheric hydrocarbon contamination, defined as biological ageing. The latter has proven to be effectively reversed by UVC irradiation. Crystal structures of both Zr and Ti oxides are very similar, thus also ZrO2 is prone to contamination by hydrocarbons. In the present study we have characterized the chemical-physical changes occurring to ZrO2 after UVC irradiation. Firstly a reduction by 3-fold of carbon present on its surface. XRD analysis has indicated that UVC irradiation treatment does not affect the crystalline structure of ZrO2, suggesting that it is possible to improve cell attachment on the surface without sacrificing the mechanical strength of the material. In addition a chemical model of interaction of cell surface proteins with the almost carbon free ZrO2 surface obtainable after UVC irradiation is proposed, pointing to the important role likely played by integrins and RGD sequences originating in soluble proteins adsorbed at the cell/ZrO2 interface. Hence in clinical practice UVC photofunctionalization could improve the soft tissue seal around dental implants functioning as a valid barrier between implant and peri-implant bone, thereby improving the long-term success of implants. Copyright © 2017. Published by Elsevier B.V.

  4. Transformation of β-Ni(OH)2 to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

    NASA Astrophysics Data System (ADS)

    Cheng, Ming-Yao; Hwang, Bing-Joe

    2007-01-01

    Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)2 to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices.

  5. Wear of enamel opposing zirconia and lithium disilicate after adjustment, polishing and glazing.

    PubMed

    Lawson, Nathaniel C; Janyavula, Sridhar; Syklawer, Sarah; McLaren, Edward A; Burgess, John O

    2014-12-01

    To compare the wear and opposing enamel wear of adjusted (A); adjusted and polished (AP); and adjusted and glazed (AG) zirconia and lithium disilicate. Specimens (n=8) were prepared of lithium disilicate (A, AP, and AG), zirconia (A, AP, and AG), veneering porcelain, and enamel (control). Surface roughness was measured for each ceramic. In vitro wear was conducted in the UAB-chewing simulator (10 N vertical load/2mm slide/20 cycles/min) with lubricant (33% glycerin) for 400,000 cycles. Isolated cusps of extracted molars were used as antagonists. Scans of the cusps and ceramics were taken at baseline and 400,000 cycles with a non-contact profilometer and super-imposed to determine wear. Data were analyzed with ANOVA and Tukey-Kramer post hoc tests (alpha=0.05). A and AP zirconia showed no detectable signs of wear, and the veneering porcelain demonstrated the most wear. All other ceramics showed significantly less volumetric loss than the veneering porcelain, comparable to enamel-enamel wear. Veneering porcelain produced the most opposing enamel wear (2.15 ± 0.58 mm(3)). AP lithium disilicate and zirconia showed the least amount of enamel wear (0.36 ± 0.09 mm(3) and 0.33 ± 0.11 mm(3) respectively). AG lithium disilicate had statistically similar enamel wear as AP lithium disilicate, but A lithium disilicate had more enamel wear. A and AG zirconia had more enamel wear than AP zirconia. No statistically significant difference was seen between the enamel-enamel group and any other group except the veneering porcelain. Zirconia has less wear than lithium disilicate. Wear of enamel opposing adjusted lithium disilicate and zirconia decreased following polishing. Zirconia experiences less and lithium disilicate experiences equivalent occlusal wear as natural enamel. It is preferable to polish zirconia and lithium disilicate after adjustment to make them wear compatible with enamel. Veneering of zirconia and lithium disilicate should be avoided in areas of occlusal

  6. On the interfacial fracture resistance of resin-bonded zirconia and glass-infiltrated graded zirconia

    PubMed Central

    Chai, Herzl; Kaizer, Marina; Chughtai, Asima; Tong, Hui; Tanaka, Carina; Zhang, Yu

    2015-01-01

    Objective A major limiting factor for the widespread use of zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded zirconia-based restorative materials. Methods The interfacial fracture energy GC was determined for adhesively bonded zirconia, graded zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline GC was measured for bonded specimens subjected to 7 days hydration at 37 °C. Long-term GC was determined for specimens exposed to 20,000 thermal cycles between 5 and 55 °C followed by 2-month aging at 37 °C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis. Results The baseline and long-term GC for graded zirconia was 2–3 and 8 times that for zirconia, respectively. More significantly, both the baseline and long-term GC of graded zirconia were similar to those for feldspathic ceramic. Significance The interfacial fracture energy of feldspathic ceramic and graded zirconia was controlled by the fracture energy of the resin cement while that of zirconia by the interface. GC for the graded zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry. PMID:26365987

  7. Synthesis of mesoporous zirconia using an amphoteric surfactant

    SciTech Connect

    Kim, A.Y.; Bruinsma, P.J.; Chen, Y.L.; Liu, J.

    1996-12-31

    An amphoteric surfactant, cocamidopropyl betaine, was used for the synthesis of mesoporous zirconia. The carboxylate functionality of the surfactant permitted strong bonding with soluble zirconium species, while the quaternary ammonium group ensured large headgroup area and high solubility under acidic conditions. An amphoteric co-template [betaine, or (carboxymethyl)trimethylammonium hydroxide] improved uniformity of the hexagonal mesophase. Transmission electron microscopy (TEM) of the as-synthesized zirconium sulfate mesophase indicated hexagonal mesostructure, and low-angle X-ray diffraction (XRD) showed a 41 {angstrom} primary d-spacing and two higher order reflections of a hexagonal lattice. High surface area zirconia was produced by controlled base treatment of the hexagonal mesophase with sodium hydroxide, followed by calcination. TEM and XRD indicated that the mesostructure was stable to 350 C.

  8. The surface area of soil organic matter

    USGS Publications Warehouse

    Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

    1990-01-01

    The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

  9. Synthesis and characterization of nanophase zirconia : reverse micelle method and neutron scattering study.

    SciTech Connect

    Li, X.

    1998-11-23

    Zirconia is an important transition-metal oxide for catalytic applications. It has been widely used in automotive exhaust treatment, methanol synthesis, isomerization, alkylation, etc. [1]. Nanophase materials have unique physiochemical properties such as quantum size effects, high surface area, uniform morphology, narrow size distribution, and improvement of sintering rates[2]. Microemulsion method provides the means for controlling the microenvironment under which specific chemical reactions may occur in favoring the formation of homogeneous, nanometer-size particles. In this paper, we report the synthesis of nanophase zirconia and the characterization of the microemulsions as well as the powders by small- and wide-angle neutron scattering techniques.

  10. Nanosilica coating for bonding improvements to zirconia

    PubMed Central

    Chen, Chen; Chen, Gang; Xie, Haifeng; Dai, Wenyong; Zhang, Feimin

    2013-01-01

    Resin bonding to zirconia cannot be established from standard methods that are currently utilized in conventional silica-based dental ceramics. The solution–gelatin (sol–gel) process is a well developed silica-coating technique used to modify the surface of nonsilica-based ceramics. Here, we use this technique to improve resin bonding to zirconia, which we compared to zirconia surfaces treated with alumina sandblasting and tribochemical silica coating. We used the shear bond strength test to examine the effect of the various coatings on the short-term resin bonding of zirconia. Furthermore, we employed field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and Fourier transform infrared spectroscopy to characterize the zirconia surfaces. Water–mist spraying was used to evaluate the durability of the coatings. To evaluate the biological safety of the experimental sol–gel silica coating, we conducted an in vitro Salmonella typhimurium reverse mutation assay (Ames mutagenicity test), cytotoxicity tests, and in vivo oral mucous membrane irritation tests. When compared to the conventional tribochemical silica coating, the experimental sol–gel silica coating provided the same shear bond strength, higher silicon contents, and better durability. Moreover, we observed no apparent mutagenicity, cytotoxicity, or irritation in this study. Therefore, the sol–gel technique represents a promising method for producing silica coatings on zirconia. PMID:24179333

  11. Air-particle abrasion on zirconia ceramic using different protocols: effects on biaxial flexural strength after cyclic loading, phase transformation and surface topography.

    PubMed

    Souza, Rodrigo O A; Valandro, Luiz F; Melo, Renata M; Machado, João P B; Bottino, Marco A; Ozcan, Mutlu

    2013-10-01

    This study evaluated the effect of different air-particle abrasion protocols on the biaxial flexural strength and structural stability of zirconia ceramics. Zirconia ceramic specimens (ISO 6872) (Lava, 3M ESPE) were obtained (N=336). The specimens (N=118, n=20 per group) were randomly assigned to one of the air-abrasion protocols: Gr1: Control (as-sintered); Gr2: 50 µm Al2O3 (2.5 bar); Gr3: 50 µm Al2O3 (3.5 bar); Gr4: 110 µm Al2O3(2.5 bar); Gr5: 110 µm Al2O3 (3.5 bar); Gr6: 30 µm SiO2 (2.5 bar) (CoJet); Gr7: 30 µm SiO2(3.5 bar); Gr8: 110 µm SiO2 (2.5 bar) (Rocatec Plus); and Gr9: 110 µm SiO2 (3.5 bar) (duration: 20 s, distance: 10 mm). While half of the specimens were tested immediately, the other half was subjected to cyclic loading in water (100,000 cycles; 50 N, 4 Hz, 37 °°C) prior to biaxial flexural strength test (ISO 6872). Phase transformation (t→m), relative amount of transformed monoclinic zirconia (FM), transformed zone depth (TZD) and surface roughness were measured. Particle type (p=0.2746), pressure (p=0.5084) and cyclic loading (p=0.1610) did not influence the flexural strength. Except for the air-abraded group with 110 µm Al2O3 at 3.5 bar, all air-abrasion protocols increased the biaxial flexural strength (MPa) (Controlnon-aged: 1,030 ± 153, Controlaged: 1,138 ± 138; Experimentalnon-aged: 1,307 ± 184-1,554 ± 124; Experimentalaged: 1,308 ± 118-1,451 ± 135) in both non-aged and aged conditions, respectively. Surface roughness (Ra) was the highest with 110 µm Al2O3(0.84 µm. FM values ranged from 0% to 27.21%, higher value for the Rocatec Plus (110 µm SiO2) and 110 µm Al2O3 groups at 3.5 bar pressure. TZD ranged between 0 and 1.43 µm, with the highest values for Rocatec Plus and 110 µm Al2O3 groups at 3.5 bar pressure. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Surface area coefficients for airship envelopes

    NASA Technical Reports Server (NTRS)

    Diehl, W S

    1922-01-01

    In naval architecture, it is customary to determine the wetted surface of a ship by means of some formula which involves the principal dimensions of the design and suitable constants. These formulas of naval architecture may be extended and applied to the calculation of the surface area of airship envelopes by the use of new values of the constants determined for this purpose. Surface area coefficients were calculated from the actual dimensions, surfaces, and volumes of 52 streamline bodies, which form a series covering the entire range of shapes used in the present aeronautical practice.

  13. Templated electrochemical deposition of zirconia thin films on "recordable CDs.".

    PubMed

    Yu, Hua-Zhong; Rowe, Aaron W; Waugh, Damien M

    2002-11-15

    In this paper, we describe a practical method of using gold films constructed from recordable compact disks (CD-Rs) as simple, inexpensive, and micropatterned conductive substrates for the fabrication of inorganic material microstructures. Extending from their application for the fabrication of self-assembled monolayers (SAMs) reported recently, bare and SAM-modified CD-R gold substrates have been used for template-directed electrodeposition of zirconia (ZrO2) thin films (i.e., the controlled formation of zirconia thin films on the different areas of the prefabricated, micrometer mountain-valley CD-R gold substrate surfaces). The present results demonstrate that the variation of the functional groups of the selected SAMs combined with electrodynamic control can be very successful to "customize" the formation and microstructure of functional inorganic thin films, which hold promise for modern technological applications.

  14. Preparation of mesoporous zirconia microspheres as inert matrix

    NASA Astrophysics Data System (ADS)

    Guo, Ting; Wang, Chen; Lv, Jinlong; Liang, Tongxiang

    2016-12-01

    Mesoporous zirconia microspheres, with a diameter of 900 μm, were prepared as an inert accelerator driven system (ADS) transmutation element matrix by the sol-gel method. The purpose of mesopores is to improve the adsorption capacity of inert matrix fuel (IMF) for minor actinides. The study indicated that the mesoporous zirconia performance was improved after the microspheres were hydrothermally treated at 150 °C, the specific surface area increased from 28.29 m2/g to 61.28 m2/g, and hydrothermal treatment avoided the cracking of the microspheres. Pre-decomposition of the organics during the hydrothermal process stabilized the mesoporous structure. The average pore diameter of mesoporous microsphere was 14.3 nm.

  15. The osseointegration of zirconia dental implants.

    PubMed

    Assal, Patrick A

    2013-01-01

    Zirconia is currently extensively used in medicine, especially in orthopedic surgery for various joint replacement appliances. Its outstanding mechanical and chemical properties have made it the "material of choice" for various types of prostheses. Its color in particular makes it a favored material to manufacture dental implants. A literature search through Medline enables one to see zirconia's potential but also to point out and identify its weaknesses. The search shows that zirconia is a biocompatible, osteoconductive material that has the ability to osseointegrate. Its strength of bonding to bone depends on the surface structure of the implant. Although interesting, the studies do not allow for the recommendation of the use of zirconia implants in daily practice. The lack of studies examining the chemical and structural composition of zirconia implants does not allow for a "gold standard" to be established in the implant manufacturing process. Randomized clinical trials (RCT) are urgently needed on surface treatments of zirconia implants intended to achieve the best possible osseointegration.

  16. The retention behaviour of polar compounds on zirconia based stationary phases under hydrophilic interaction liquid chromatography conditions.

    PubMed

    Kučera, R; Kovaříková, P; Klivický, M; Klimeš, J

    2011-09-28

    The most separations in HILIC mode are performed on silica-based supports. Nevertheless, recently published results have indicated that the metal oxides stationary phases also possess the ability to interact with hydrophilic compounds under HILIC conditions. This paper primarily describes the retention behaviour of model hydrophilic analytes (4-aminobenzene sulfonic acid, 4-aminobenzoic acid, 4-hydroxybenzoic acid, 3,4-diaminobenzoic acid, 3-aminophenol and 3-nitrophenol) on the polybutadine modified zirconia in HILIC. The results were simultaneously compared with a bare zirconia and a silica-based HILIC phase. The mobile phase strength, pH and the column temperature were systematically modified to assess their impact on the retention of model compounds. It was found that the retention of our model hydrophilic analytes on both zirconia phases was mainly governed by adsorption while on the silica-based HILIC phase partitioning was primarily involved. The ability of ligand-exchange interactions of zirconia surface with a carboxylic moiety influenced substantially the response of carboxylic acids on the elevated temperature as well as to the change of the mobile phase pH in contrast to the silica phase. However, no or negligible ligand-exchange interactions were observed for sulfanilic acid. The results of this study clearly demonstrated the ability of modified zirconia phase to retain polar acidic compounds under HILIC conditions, which might substantially enlarge the application area of the zirconia-based stationary phases. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Measuring the surface area of fasteners

    Treesearch

    Douglas R. Rammer; Samuel L. Zelinka

    2011-01-01

    New product provides a easy way for companies to identify the surface area of threaded and nonthreaded fasteners, especially as changes in wood preservative treatments act to accelerate metal fastener corrosion in wood.

  18. Grooved Surface and Area of Boulders

    NASA Image and Video Library

    2012-04-18

    This image of asteroid Vesta from NASA Dawn spacecraft shows an area of the surface that is both grooved and smooth, which gives it an undulating appearance. This image is located in Vesta Numisia quadrangle, near the Vestan equator.

  19. Phase stability of zirconia at nanoscale.

    NASA Astrophysics Data System (ADS)

    Sabiryanov, Renat; Mei, W. N.

    2004-03-01

    There are three phases of ZrO2, namely cubic, tetragonal and monoclinic. Cubic phase of zirconia is usually stabilized by various dopants such as yttria and magnesia. However, it has been observed that these stablizers are indeed the source failure of doped ZrO2 in both orthopaedics and in ZrO2 used in high temperature applications. Recently, the cubic zirconia was fabricated as granular media with the grain sizes less than 17nm. We examine the phase stability in zirconia nanoparticles using first principle electronic structure method. We observe considerable relaxation of lattice in the monoclinic phase near the surface. This effect combined with surface tension and possibly vacancies in nanostructures are sources of stability of cubic zirconia at nanoscale. We performed calculation of the surface tension calculations for the pure (001) surface. The uniform compressive strain is applied in the plane of the slab to find the elastic response of the system. The slab is allowed to relax in the perpendicular direction. Uniform compressive strain in the plane of the slab causes increase in the distance between Zr and O layers for (001) surface (as a solid tends to preserve the volume). For cubic it gives -0.65N/m, while for monoclinic -0.48N/m. Furthermore, the solid-gas surface tension is a fundamental physical/chemical property of a solid, which affects its wetting properties. Therefore, cubic zirconia is more suitable to design the material combining wettability, ductility and hardness.

  20. Aluminum doped zirconia nanopowders: Wet-chemical synthesis and structural analysis by Rietveld refinement

    SciTech Connect

    Srdic, Vladimir V. Rakic, Srdan; Cvejic, Zeljka

    2008-10-02

    Alumina/zirconia nanopowders, with up to 20 mol% Al{sub 2}O{sub 3}, were prepared by wet-chemical synthesis technique, using controlled hydrolysis of alkoxides. The as-synthesized powders are amorphous, have very high specific surface area and the corresponding particle size smaller than 4 nm. Amorphous powders with 0, 10 and 20 mol% Al{sub 2}O{sub 3} crystallize at 460, 692 and 749 deg. C, respectively, as a single-phase tetragonal zirconia, without any traces of alumina phases. Rietvled refinement of X-ray diffraction data, used for the detailed structural analysis of annealed nanopowders, showed that the high-temperature zirconia phase is stabilized due to the formation of ZrO{sub 2}/Al{sub 2}O{sub 3} solid solutions. High solubility of alumina in the tetragonal zirconia (up to 28.6 at% Al{sup 3+}) and stabilization of tetragonal zirconia solid solution up to high temperature (as high as 1150 deg. C) were also confirmed.

  1. Initial bacterial adhesion on resin, titanium and zirconia in vitro

    PubMed Central

    Lee, Byung-Chul; Jung, Gil-Yong; Kim, Dae-Joon

    2011-01-01

    PURPOSE The aim of this in vitro study was to investigate the adhesion of initial colonizer, Streptococcus sanguis, on resin, titanium and zirconia under the same surface polishing condition. MATERIALS AND METHODS Specimens were prepared from Z-250, cp-Ti and 3Y-TZP and polished with 1 µm diamond paste. After coating with saliva, each specimen was incubated with Streptococcus sanguis. Scanning electron microscope, crystal violet staining and measurement of fluorescence intensity resulting from resazurin reduction were performed for quantifying the bacterial adhesion. RESULTS Surface of resin composite was significantly rougher than that of titanium and zirconia, although all tested specimens are classified as smooth. The resin specimens showed lower value of contact angle compared with titanium and zirconia specimens, and had hydrophilic surfaces. The result of scanning electron microscopy demonstrated that bound bacteria were more abundant on resin in comparison with titanium and zirconia. When total biofilm mass determined by crystal violet, absorbance value of resin was significantly higher than that of titanium or zirconia. The result of relative fluorescence intensities also demonstrated that the highest fluorescence intensity was found on the surface of resin. Absorbance value and fluorescence intensity on titanium was not significantly different from those on zirconia. CONCLUSION Resin specimens showed the roughest surface and have a significantly higher susceptibility to adhere Streptococcus sanguis than titanium and zirconia when surfaces of each specimen were polished under same condition. There was no significant difference in bacteria adhesion between titanium and zirconia in vitro. PMID:21814616

  2. The effect of graded glass-zirconia structure on the bond between core and veneer in layered zirconia restorations.

    PubMed

    Liu, Ruoyu; Sun, Ting; Zhang, Yanli; Zhang, Yaokun; Jiang, Danyu; Shao, Longquan

    2015-06-01

    The aim of this study was to test the hypothesis that a graded glass-zirconia structure can strengthen the core-veneer bond in layered zirconia materials. A graded glass-zirconia structure was fabricated by infiltrating glass compositions developed in our laboratory into a presintered yttria tetrahedral zirconia polycrystal (Y-TZP) substrate by the action of capillary forces. The wettability of the infiltrated glass and Y-TZP substrate was investigated by the sessile drop technique. The microstructures of the graded glass-zirconia structure were examined by scanning electron microscopy (SEM). The phase structure characterization in the graded glass-zirconia structure were identified by X-ray diffraction (XRD) analysis. The elastic modulus and hardness of the graded glass-zirconia structure were evaluated from nanoindentations. Further, the shear bond strength (SBS) of the graded glass-zirconia structure and veneering porcelain was also evaluated. SEM images confirmed the formation of the graded glass-zirconia structure. Glass frits wet the Y-TZP substrate at 1200 °C with a contact angle of 43.2°. Only a small amount of t-m transformation was observed in as-infiltrated Y-TZP specimens. Nanoindentation studies of the glass-zirconia graded structure showed that the elastic modulus and hardness of the surface glass layer were higher than those of the dense Y-TZP layer. The mean SBS values for the graded glass-zirconia structure and veneering porcelain (24.35 ± 0.40 MPa) were statistically higher than those of zirconia and veneering porcelain (9.22 ± 0.20 MPa) (P<0.05). A graded glass-zirconia structure can be fabricated by the glass infiltration/densification technique, and this structure exhibits a strong core-veneer bond. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

    PubMed

    Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

    2016-01-01

    The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

  4. Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

    DOEpatents

    Wrenn, G.E. Jr.; Holcombe, C.E. Jr.

    1988-09-13

    A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

  5. Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

    DOEpatents

    Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.

    1988-01-01

    A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

  6. Surface moisture estimation in urban areas

    NASA Astrophysics Data System (ADS)

    Jiang, Yitong

    Surface moisture is an important parameter because it modifies urban microclimate and surface layer meteorology. The primary objectives of this paper are: 1) to analyze the impact of surface roughness from buildings on surface moisture in urban areas; and 2) to quantify the impact of surface roughness resulting from urban trees on surface moisture. To achieve the objectives, two hypotheses were tested: 1) the distribution of surface moisture is associated with the structural complexity of buildings in urban areas; and 2) The distribution and change of surface moisture is associated with the distribution and vigor of urban trees. The study area is Indianapolis, Indiana, USA. In the part of the morphology of urban trees, Warren Township was selected due to the limitation of tree inventory data. To test the hypotheses, the research design was made to extract the aerodynamic parameters, such as frontal areas, roughness length and displacement height of buildings and trees from Terrestrial and Airborne LiDAR data, then to input the aerodynamic parameters into the urban surface energy balance model. The methodology was developed for comparing the impact of aerodynamic parameters from LiDAR data with the parameters that were derived empirically from land use and land cover data. The analytical procedures are discussed below: 1) to capture the spatial and temporal variation of surface moisture, daily and hourly Land Surface Temperature (LST) were downscaled from 4 km to 1 km, and 960 m to 30 m, respectively, by regression between LST and various components that impact LST; 2) to estimate surface moisture, namely soil moisture and evapotranspiration (ET), land surfaces were classified into soil, vegetation, and impervious surfaces, using Linear Spectral Mixture Analysis (LSMA); 3) aerodynamic parameters of buildings and trees were extracted from Airborne and Terrestrial LiDAR data; 4) the Temperature-Vegetation-Index (TVX) method, and the Two-Source-Energy-Balance (TSEB

  7. Surface area-volume ratios in insects.

    PubMed

    Kühsel, Sara; Brückner, Adrian; Schmelzle, Sebastian; Heethoff, Michael; Blüthgen, Nico

    2017-10-01

    Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area-volume (SA/V) ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders (Diptera, Hymenoptera, Lepidoptera, and Coleoptera). Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 °C to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling (residuals of the SA/V ∼ mass(2/3) relationship). Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/V ratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity. © 2016 Institute of Zoology, Chinese Academy of Sciences.

  8. Zirconia in dental implantology: A review

    PubMed Central

    Apratim, Abhishek; Eachempati, Prashanti; Krishnappa Salian, Kiran Kumar; Singh, Vijendra; Chhabra, Saurabh; Shah, Sanket

    2015-01-01

    Background: Titanium has been the most popular material of choice for dental implantology over the past few decades. Its properties have been found to be most suitable for the success of implant treatment. But recently, zirconia is slowly emerging as one of the materials which might replace the gold standard of dental implant, i.e., titanium. Materials and Methods: Literature was searched to retrieve information about zirconia dental implant and studies were critically analyzed. PubMed database was searched for information about zirconia dental implant regarding mechanical properties, osseointegration, surface roughness, biocompatibility, and soft tissue health around it. The literature search was limited to English language articles published from 1975 to 2015. Results: A total of 45 papers met the inclusion criteria for this review, among the relevant search in the database. Conclusion: Literature search showed that some of the properties of zirconia seem to be suitable for making it an ideal dental implant, such as biocompatibility, osseointegration, favourable soft tissue response and aesthetics due to light transmission and its color. At the same time, some studies also point out its drawbacks. It was also found that most of the studies on zirconia dental implants are short-term studies and there is a need for more long-term clinical trials to prove that zirconia is worth enough to replace titanium as a biomaterial in dental implantology. PMID:26236672

  9. Fabrication of zirconia composite membrane by in-situ hydrothermal technique and its application in separation of methyl orange.

    PubMed

    Kumar, R Vinoth; Ghoshal, Aloke Kumar; Pugazhenthi, G

    2015-11-01

    The main objective of the work was preparation of zirconia membrane on a low cost ceramic support through an in-situ hydrothermal crystallization technique for the separation of methyl orange dye. To formulate the zirconia film on the ceramic support, hydrothermal reaction mixture was prepared using zirconium oxychloride as a zirconia source and ammonia as a precursor. The synthesized zirconia powder was characterized by X-ray diffractometer (XRD), N2 adsorption/desorption isotherms, Thermogravimetric analysis (TGA), Fourier transform infrared analysis (FTIR), Energy-dispersive X-ray (EDX) analysis and particle size distribution (PSD) to identify the phases and crystallinity, specific surface area, pore volume and pore size distribution, thermal behavior, chemical composition and size of the particles. The porosity, morphological structure and pure water permeability of the prepared zirconia membrane, as well as ceramic support were investigated using the Archimedes' method, Field emission scanning electron microscopy (FESEM) and permeability. The specific surface area, pore volume, pore size distribution of the zirconia powder was found to be 126.58m(2)/g, 3.54nm and 0.3-10µm, respectively. The porosity, average pore size and pure water permeability of the zirconia membrane was estimated to be 42%, 0.66µm and 1.44×10(-6)m(3)/m(2)skPa, respectively. Lastly, the potential of the membrane was investigated with separation of methyl orange by means of flux and rejection as a function of operating pressure and feed concentration. The rejection was found to decrease with increasing the operating pressure and increases with increasing feed concentrations. Moreover, it showed a high ability to reject methyl orange from aqueous solution with a rejection of 61% and a high permeation flux of 2.28×10(-5)m(3)/m(2)s at operating pressure of 68kPa.

  10. Periodontal inflamed surface area: quantifying inflammatory burden.

    PubMed

    Nesse, Willem; Abbas, Frank; van der Ploeg, Ids; Spijkervet, Frederik Karst Lucien; Dijkstra, Pieter Ubele; Vissink, Arjan

    2008-08-01

    Currently, a large variety of classifications is used for periodontitis as a risk factor for other diseases. None of these classifications quantifies the amount of inflamed periodontal tissue, while this information is needed to assess the inflammatory burden posed by periodontitis. To develop a classification of periodontitis that quantifies the amount of inflamed periodontal tissue, which can be easily and broadly applied. A literature search was conducted to look for a classification of periodontitis that quantified the amount of inflamed periodontal tissue. A classification that quantified the root surface area affected by attachment loss was found. This classification did not quantify the surface area of inflamed periodontal tissue, however. Therefore, an Excel spreadsheet was developed in which the periodontal inflamed surface area (PISA) is calculated using clinical Attachment Level (CAL), recessions and bleeding on probing (BOP). The PISA reflects the surface area of bleeding pocket epithelium in square millimetres. The surface area of bleeding pocket epithelium quantifies the amount of inflamed periodontal tissue. A freely downloadable spreadsheet is available to calculate the PISA. PISA quantifies the inflammatory burden posed by periodontitis and can be easily and broadly applied.

  11. Digital workflow in full-arch implant rehabilitation with segmented minimally veneered monolithic zirconia fixed dental prostheses: 2-year clinical follow-up.

    PubMed

    Papaspyridakos, Panos; Kang, Kiho; DeFuria, Catherine; Amin, Sarah; Kudara, Yukio; Weber, Hans-Peter

    2017-08-09

    To illustrate a digital workflow in full-arch implant rehabilitation with minimally veneered monolithic zirconia and to report the outcomes including technical complications. Three patients (5 edentulous arches) received full-arch fixed implant rehabilitation with monolithic zirconia and mild facial porcelain veneering involving a digital workflow. The incisal edges and occluding surface areas were milled out of monolithic zirconia to reduce the possibility of chipping. Porcelain veneering was applied on the facial aspect to improve the esthetic result. Outcomes and technical complications are reported after 2 years of clinical and radiographic follow-up. Implant and prosthesis survival rates were 100% after a short-term follow-up of 2 years. Technical complications were encountered in one patient. They did not adversely affect prosthesis survival or patient satisfaction and were easily addressed. A digital workflow for the design and fabrication of full-arch monolithic zirconia implant fixed implant prostheses has benefits, but caution is necessary during CAD planning of the prosthesis to ensure a successful outcome. Long-term clinical studies are needed to corroborate the findings discussed in this report. This article presents an integrated digital workflow that was implemented for the implant-prosthodontic rehabilitation of three edentulous patients with monolithic zirconia prostheses. Monolithic zirconia has been successfully incorporated in implant prosthodontics in an effort to reduce the technical complications associated with bilayered ceramics. This workflow simplifies design and fabrication of the zirconia prostheses. However, caution should be taken during CAD planning of the prosthesis to make sure the zirconia cylinder is sufficiently thick at the interface with the titanium insert. Additionally, when cutback is planned for facial porcelain veneering, the functional occluding cusps and incisal edges should be fabricated in monolithic zirconia to avoid

  12. Damage Maps of Veneered Zirconia under Simulated Mastication

    PubMed Central

    Kim, Jae-Won; Kim, Joo-Hyung; Janal, Malvin N.; Zhang, Yu

    2016-01-01

    Zirconia based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesize that veneer chipping/delamination is a result of the propagation of near-contact induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, flat porcelain veneered zirconia plates were cemented to dental composites and cyclically loaded (contact–slide–liftoff) at an inclination angle as a simplified model of zirconia based restorations under occlusion. In the light of in-situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, postmortem damage evaluation of porcelain/zirconia/composite trilayers using a sectioning technique revealed that deep penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

  13. Damage maps of veneered zirconia under simulated mastication.

    PubMed

    Kim, J-W; Kim, J-H; Janal, M N; Zhang, Y

    2008-12-01

    Zirconia-based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesized that veneer chipping/delamination is a result of the propagation of near-contact-induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, we cemented flat porcelain-veneered zirconia plates onto dental composites and cyclically loaded them (contact-slide-liftoff) at an inclination angle as a simplified model of zirconia-based restorations under occlusion. In light of in situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, post mortem damage evaluation of porcelain/zirconia/composite trilayers by a sectioning technique revealed that deep-penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed.

  14. Fabrication and characterization of dense zirconia and zirconia-silica ceramic nanofibers.

    PubMed

    Xu, Xiaoming; Guo, Guangqing; Fan, Yuwei

    2010-09-01

    The objective of this study was to prepare dense zirconia-yttria (ZY), zirconia-silica (ZS) and zirconia-yttria-silica (ZYS) nanofibers as reinforcing elements for dental composites. Zirconium (IV) propoxide, yttrium nitrate hexahydrate, and tetraethyl orthosilicate (TEOS) were used as precursors for the preparation of zirconia, yttria, and silica sols. A small amount (1-1.5 wt%) of polyethylene oxide (PEO) was used as a carry polymer. The sols were preheated at 70 degrees C before electrospinning and their viscosity was measured with a viscometer at different heating time. The gel point was determined by viscosity-time (eta-t) curve. The ZY, ZS and ZYS gel nanofibers were prepared using a special reactive electrospinning device under the conditions near the gel point. The as-prepared gel nanofibers had diameters between 200 and 400 nm. Dense (nonporous) ceramic nanofibers of zirconia-yttria (96/4), zirconia-silica (80/20) and zirconia-yttria-silica (76.8/3.2/20) with diameter of 100-300 nm were obtained by subsequent calcinations at different temperatures. The gel and ceramic nanofibers obtained were characterized by scanning electron microscope (SEM), high-resolution field-emission scanning electron microscope (FE-SEM), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectrometer (FT-IR), and X-ray diffraction (XRD). SEM micrograph revealed that ceramic ZY nanofibers had grained structure, while ceramic ZS and ZYS nanofibers had smooth surfaces, both showing no visible porosity under FE-SEM. Complete removal of the polymer PEO was confirmed by TGA/DSC and FT-IR. The formation of tetragonal phase of zirconia and amorphous silica was proved by XRD. In conclusion, dense zirconia-based ceramic nanofibers can be fabricated using the new reactive sol-gel electrospinning technology with minimum organic polymer additives.

  15. Ionic Conductivity of Mesostructured Yttria-Stabilized Zirconia Thin Films with Cubic Pore Symmetry—On the Influence of Water on the Surface Oxygen Ion Transport.

    PubMed

    Elm, Matthias T; Hofmann, Jonas D; Suchomski, Christian; Janek, Jürgen; Brezesinski, Torsten

    2015-06-10

    Thermally stable, ordered mesoporous thin films of 8 mol % yttria-stabilized zirconia (YSZ) were prepared by solution-phase coassembly of chloride salt precursors with an amphiphilic diblock copolymer using an evaporation-induced self-assembly process. The resulting material is of high quality and exhibits a well-defined three-dimensional network of pores averaging 24 nm in diameter after annealing at 600 °C for several hours. The wall structure is polycrystalline, with grains in the size range of 7 to 10 nm. Using impedance spectroscopy, the total electrical conductivity was measured between 200 and 500 °C under ambient atmosphere as well as in dry atmosphere for oxygen partial pressures ranging from 1 to 10(-4) bar. Similar to bulk YSZ, a constant ionic conductivity is observed over the whole oxygen partial pressure range investigated. In dry atmosphere, the sol-gel derived films have a much higher conductivity, with different activation energies for low and high temperatures. Overall, the results indicate a strong influence of the surface on the transport properties in cubic fluorite-type YSZ with high surface-to-volume ratio. A qualitative defect model which includes surface effects (annihilation of oxygen vacancies as a result of water adsorption) is proposed to explain the behavior and sensitivity of the conductivity to variations in the surrounding atmosphere.

  16. Electrochemical, Structural and Surface Characterization of Nickel/Zirconia Solid Oxide Fuel Cell Anodes in Coal Gas Containing Antimony

    SciTech Connect

    Marina, Olga A.; Pederson, Larry R.; Coyle, Christopher A.; Thomsen, Edwin C.; Nachimuthu, Ponnusamy; Edwards, Danny J.

    2011-02-27

    The interaction of antimony with the nickel-zirconia solid oxide fuel cell (SOFC) anode has been investigated. Tests with both anode-supported and electrolyte-supported button cells were performed at 700 and 800oC in synthetic coal gas containing 10 ppb to 9 ppm antimony. Minor performance loss was observed immediately after Sb introduction to coal gas resulting in ca. 5 % power output drop. While no further degradation was observed during the following several hundred hours of testing, cells abruptly and irreversibly failed after 800-1500 hours depending on Sb concentration and test temperature. Antimony was found to interact strongly with nickel and result in extensive alteration phase formation, consistent with expectations based on thermodynamic properties. Nickel antimonide phases, NiSb and Ni5Sb2, were partially coalesced into large grains and eventually affected electronic percolation through the anode support. Initial degradation was attributed to diffusion of antimony to the active anode/electrolyte interface to form an adsorption layer.

  17. Effect of polishing instruments and polishing regimens on surface topography and phase transformation of monolithic zirconia: An evaluation with XPS and XRD analysis.

    PubMed

    Al-Haj Husain, Nadin; Camilleri, Josette; Özcan, Mutlu

    2016-12-01

    Polishing procedures might alter monolithic zirconia (MZ) surface resulting in phase changes that can be deleterious for clinical performance and antagonist tooth wear. This study investigated the topographical features and phase transformation in MZ after polishing with different regimens simulating the clinical workflow. ​ MZ specimens (Katana Zirconia HT, Kuraray-Noritake) (12×12×1.8 mm(3)) were grinded and polished using one of the five systems assessed: BG: Silicone carbide polishers (Brownie, Greenie, Super Greenie); CG: Diamond impregnated ceramic polisher kit (Ceragloss); EV: Synthetically bonded grinder interspersed with diamond (EVE Kit); SL: Urethane coated paper with aluminium oxide grits (Soflex Finishing and Polishing System Kit) and DB: Diamond bur (8 µm). Polished specimens were initially roughened with 220 µm diamond burs (Grinding Bur-GB) (10 s, 160.000160,000 rpm) and considered for baseline measurements. Polishing regimens were performed for 10 s using a slow-speed hand piece under water-cooling except for SL, in a custom made device (750 g; 5000 and 75,000 rpm). Surface roughnesses, phase changes (XRD) were assessed, surface characterization was performed (SEM, EDS). The highest roughness was obtained with the EV system (1.11 µm) compared to those of other systems (0.13-0.4 µm) (pθ and minor peak at 34.94°2θ. While GB, CG, EV, SL and DB exhibited a peak shift to the left, BG demonstrated a right peak shift on the 2θ scale. Monoclinic phase change was not noted in any of the groups. All polishing methods, except BG, exhibited a peak shift towards the lower angles of the 2-theta scale. Since the peak shifts were in the order of fractions of an angle they are attributed to stress formation rather than a phase change in the material. Thus, all polishing systems tested may not be detrimental for the phase transformation of MZ. EV system resulted in the highest roughness and none of the polishing regimens restored the polishability to the

  18. Enhanced Biological Behavior of In Vitro Human Gingival Fibroblasts on Cold Plasma-Treated Zirconia.

    PubMed

    Zheng, Miao; Yang, Yang; Liu, Xiao-Qiang; Liu, Ming-Yue; Zhang, Xiao-Fei; Wang, Xin; Li, He-Ping; Tan, Jian-Guo

    2015-01-01

    To evaluate whether atmospheric-pressure dielectric-barrier-discharge plasma treatment of zirconia enhances its biocompatibility with human gingival fibroblasts. The zirconia disks were divided into four groups and treated using helium atmospheric-pressure dielectric-barrier-discharge plasmas for 30, 60 or 90 s or left untreated. The surface morphology, wettability and chemical elements were analyzed. Fibroblasts density, morphology, morphometry and attachment-related genes expression were measured at different time points from 3 to 72 h. After plasma treatment, the surface morphology and roughness remained the same, while the contact angle decreased from 78.31° to 43.71°, and the surface C/O ratio decreased from 3.17 to 0.89. The surficial areas and perimeters of HGFs were increased two-fold in the treated groups at 3 h. Fibroblasts density increased on treated disks at all time points, especially the ones treated for 60 s. Attachment-related genes in the groups treated for 30 and 60 s were significantly higher at 3 and 24 h. The helium atmospheric-pressure dielectric-barrier-discharge plasma treatment enhances the biological behavior of fibroblasts on zirconia by increasing the expression of attachment-related genes within 24 h and promoting the cell density during longer culture times. Wettability of zirconia, an important physicochemical property, has a vital influence on the cell behaviors.

  19. Enhanced Biological Behavior of In Vitro Human Gingival Fibroblasts on Cold Plasma-Treated Zirconia

    PubMed Central

    Zheng, Miao; Yang, Yang; Liu, Xiao-Qiang; Liu, Ming-Yue; Zhang, Xiao-Fei; Wang, Xin; Li, He-Ping; Tan, Jian-Guo

    2015-01-01

    Objective To evaluate whether atmospheric-pressure dielectric-barrier-discharge plasma treatment of zirconia enhances its biocompatibility with human gingival fibroblasts. Materials and Methods The zirconia disks were divided into four groups and treated using helium atmospheric-pressure dielectric-barrier-discharge plasmas for 30, 60 or 90 s or left untreated. The surface morphology, wettability and chemical elements were analyzed. Fibroblasts density, morphology, morphometry and attachment-related genes expression were measured at different time points from 3 to 72 h. Results After plasma treatment, the surface morphology and roughness remained the same, while the contact angle decreased from 78.31° to 43.71°, and the surface C/O ratio decreased from 3.17 to 0.89. The surficial areas and perimeters of HGFs were increased two-fold in the treated groups at 3 h. Fibroblasts density increased on treated disks at all time points, especially the ones treated for 60 s. Attachment-related genes in the groups treated for 30 and 60 s were significantly higher at 3 and 24 h. Conclusion The helium atmospheric-pressure dielectric-barrier-discharge plasma treatment enhances the biological behavior of fibroblasts on zirconia by increasing the expression of attachment-related genes within 24 h and promoting the cell density during longer culture times. Wettability of zirconia, an important physicochemical property, has a vital influence on the cell behaviors. PMID:26461253

  20. In vitro color changes of soft tissues caused by dyed fluorescent zirconia and nondyed, nonfluorescent zirconia in thin mucosa.

    PubMed

    Happe, Arndt; Schulte-Mattler, Verena; Strassert, Christian; Naumann, Michael; Stimmelmayr, Michael; Zoller, Joachim E; Rothamel, Daniel

    2013-01-01

    Abutment material selection may have an effect on the color of the peri-implant soft tissue, especially in thin mucosa. The objective of this in vitro study was to investigate the effect of titanium, zirconia, and dyed fluorescent zirconia on the color of 1.5-mm-thick mucosa. Ten pig maxillae were used to simulate thin mucosa according to a previously published setup. Three different abutment materials were placed under the mucosa, and the color of the soft tissue was evaluated using a spectrophotometer. The test area without underlying material was used as a control. Whereas titanium induced visible color change values of ΔE7.3, significantly above the threshold level of ΔE3.7 (P < .05, Student t test), the changes after insertion of zirconia ( ΔE3.7) and dyed fluorescent zirconia (3.5) were not statistically different from the visible threshold of ΔE3.7 (P < .05, Student t test). The difference between the two zirconia specimens was not statistically significant, although the dyed zirconia material was darker; the color difference was ΔE10.35 between the two. In contrast to titanium, neither nondyed zirconia nor dyed fluorescent zirconia changed the gingival coloration. Moreover, shading of white zirconia with a fluorescent dye leads to an all-ceramic abutment material that mimics the optical properties of natural teeth.

  1. Contact damage in an yttria stabilized zirconia: implications.

    PubMed

    Zhou, J; Mah, J; Shrotriya, P; Mercer, C; Soboyejo, W O

    2007-01-01

    This paper presents the results of a combined experimental and computational study of contact damage in a 3 mole% yttria partially stabilized zirconia (3-YSZ) that is relevant to hip implants and dental restorations. Contact-induced loading in real applications is idealized using Hertzian contact model to explain plasticity phenomena and failure mechanisms observed under monotonic and cyclic loading. Under monotonic loading, the elastic moduli increase with increasing loading levels. Under cyclic loading, the ceramic specimens fail with progressive cone cracking. X-ray analyses reveal that stress-induced phase transformation (from tetragonal to monoclinic phases) occurs under cyclic contact loading above the critical load levels (approximately 8.5 kN). Furthermore, when the cyclic loading level (5.0 kN) is less than a critical load levels (7.5 kN) that is required to induce surface cone cracks, significant plastic damage is observed in the subsurface zone underneath the contact area. These suggest that the cyclic contact loading induce both plastic damage and tetragonalto-monoclinic phase transformation in the 3-YSZ, leading to significant degradation in long-term strength. The implications of the results are discussed for the design of zirconia femoral heads in total hip replacements and zirconia crowns in dental restoration.

  2. Physicochemical properties, cytotoxicity, and antimicrobial activity of sulphated zirconia nanoparticles

    PubMed Central

    Mftah, Ae; Alhassan, Fatah H; Al-Qubaisi, Mothanna Sadiq; El Zowalaty, Mohamed Ezzat; Webster, Thomas J; Sh-eldin, Mohammed; Rasedee, Abdullah; Taufiq-Yap, Yun Hin; Rashid, Shah Samiur

    2015-01-01

    Nanoparticle sulphated zirconia with Brønsted acidic sites were prepared here by an impregnation reaction followed by calcination at 600°C for 3 hours. The characterization was completed using X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, Brunner-Emmett-Teller surface area measurements, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy. Moreover, the anticancer and antimicrobial effects were investigated for the first time. This study showed for the first time that the exposure of cancer cells to sulphated zirconia nanoparticles (3.9–1,000 μg/mL for 24 hours) resulted in a dose-dependent inhibition of cell growth, as determined by (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Similar promising results were observed for reducing bacteria functions. In this manner, this study demonstrated that sulphated zirconia nanoparticles with Brønsted acidic sites should be further studied for a wide range of anticancer and antibacterial applications. PMID:25632233

  3. Osmosis and Surface Area to Volume Ratio.

    ERIC Educational Resources Information Center

    Barrett, D. R. B.

    1984-01-01

    Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

  4. Osmosis and Surface Area to Volume Ratio.

    ERIC Educational Resources Information Center

    Barrett, D. R. B.

    1984-01-01

    Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

  5. Volumes and surface areas of pendular rings

    USGS Publications Warehouse

    Rose, W.

    1958-01-01

    A packing of spheres is taken as a suitable model of porous media. The packing may be regular and the sphere size may be uniform, but in general, both should be random. Approximations are developed to give the volumes and surface areas of pendular rings that exist at points of sphere contact. From these, the total free volume and interfacial specific surface area are derived as expressive of the textural character of the packing. It was found that the log-log plot of volumes and surface areas of pendular rings vary linearly with the angle made by the line joining the sphere centers and the line from the center of the largest sphere to the closest edge of the pendular ring. The relationship, moreover, was found not to be very sensitive to variation in the size ratio of the spheres in contact. It also was found that the addition of pendular ring material to various sphere packings results in an unexpected decrease in the surface area of the boundaries that confine the resulting pore space. ?? 1958 The American Institute of Physics.

  6. Comparative evaluation of shear bond strengths of veneering porcelain to base metal alloy and zirconia substructures before and after aging – An in vitro study

    PubMed Central

    Sreekala, Laju; Narayanan, Mahesh; Eerali, Sunil M.; Eerali, Susil M.; Varghese, Joju; Zainaba Fathima, A. l.

    2015-01-01

    Objective: The aim of this study was to evaluate and compare the shear bond strength of veneering porcelain to base metal alloy and zirconia substructures before and after aging. Scanning electron microscopy (SEM) was used to determine the failure pattern. Materials and Methods: Twenty rectangular blocks (9 mm length × 4 mm height × 4 mm width) of base metal alloy (Bellabond plus, Bego, Germany) and zirconia (Will ceramZ zirconia K block) were fabricated for shear bond strength test. Surface of the base metal alloy block (4 mm × 4 mm area) was veneered with corresponding veneering porcelain (Ivoclar, IPS classic, vivadent). Similarly, surface of the zirconia rectangular block (4 mm × 4 mm) was veneered with corresponding veneering ceramic (Cercon ceram kiss, Degudent). Out of forty rectangular porcelain veneered core specimen, ten porcelain veneered base metal alloy specimen and ten porcelain veneered zirconia specimen were immersed in water at 37°C for one month to simulate the oral environment. Results: On comparison, the highest shear bond strength value was obtained in porcelain veneered base metal alloy before aging group followed by porcelain veneered base metal alloy after aging group, Porcelain veneered zirconia before aging group, porcelain veneered zirconia after aging group. SEM analysis revealed predominantly cohesive failure of veneering ceramic in all groups. Conclusion: Porcelain veneered base metal alloy samples showed highest shear bond strength than porcelain veneered zirconia samples. Study concluded that aging had an influence on shear bond strength. Shear bond strength was found to be decreasing after aging. SEM analysis revealed cohesive failure of veneering ceramic in all groups suggestive of higher bond strength of the interface than cohesive strength of ceramic. Hence, it was concluded that veneering ceramic was the weakest link. PMID:26942121

  7. Human body surface area: a theoretical approach.

    PubMed

    Wang, Jianfeng; Hihara, Eiji

    2004-04-01

    Knowledge of the human body surface area has important applications in medical practice, garment design, and other engineering sizing. Therefore, it is not surprising that several expressions correlating body surface area with direct measurements of body mass and length have been reported in the literature. In the present study, based on the assumption that the exterior shape of the human body is the result of convex and concave deformations from a basic cylinder, we derive a theoretical equation minimizing body surface area (BSA) at a fixed volume (V): BSA=(9pi VL)(0.5), where L is the reference length of the body. Assuming a body density value of 1,000 kg.m(-3), the equation becomes BSA=(BM.BH/35.37)(0.5), where BSA is in square meters, BM is the body mass in kilograms, and BH is the body height in meters. BSA values calculated by means of this equation fall within +/-7% of the values obtained by means of the equations available in the literature, in the range of BSA from children to adults. It is also suggested that the above equation, which is obtained by minimizing the outer body surface at a fixed volume, implies a fundamental relation set by the geometrical constraints governing the growth and the development of the human body.

  8. Osteogenic responses to zirconia with hydroxyapatite coating by aerosol deposition.

    PubMed

    Cho, Y; Hong, J; Ryoo, H; Kim, D; Park, J; Han, J

    2015-03-01

    Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. © International & American Associations for Dental Research 2015.

  9. Osteogenic Responses to Zirconia with Hydroxyapatite Coating by Aerosol Deposition

    PubMed Central

    Cho, Y.; Hong, J.; Ryoo, H.; Kim, D.; Park, J.

    2015-01-01

    Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. PMID:25586588

  10. Homogeneous precipitation synthesis and electrical properties of scandia stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Zhang, Yawen; Liao, Chunsheng; Yan, Chunhua

    2001-12-01

    Homogeneous precipitation employing urea was utilized to prepare ultrafine and weakly-agglomerated 8 mol% scandia-stabilized zirconia (8ScSZ) powders. Their crystal structure, particle and electrical properties were investigated by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, thermo-gravimetry and differential thermal analysis, BET surface area analysis, and impedance spectroscopy, respectively. 8ScSZ polycrystals in a pure cubic phase were obtained after sintering at a low temperature of 600 °C. Elevating sintering temperature can increase the oxide ion conductivity, especially the grain boundary conductivity.

  11. Dielectric property measurement of zirconia fibers at high temperatures

    SciTech Connect

    Vogt, G.J.; Tinga, W.R.; Plovnick, R.H.

    1995-05-01

    Using a self-heating, electronically tunable microwave dielectrometer, the complex dielectric constant of zirconia-based filaments was measured at 915 MHz from 350{degrees} to 1100{degrees}C. This fibrous material cools rapidly to near room temperature within several seconds due to a large surface area to volume ratio. Such rapid sample cooling necessitates the use of a self-heating technique to measure the complex dielectric constant at temperatures up to 1100{degrees}C. Sample temperature was measured with optical fiber thermometry. The effect of sample temperature measurement on data accuracy is discussed.

  12. Hydrothermal synthesis and characterization of zirconia based catalysts

    SciTech Connect

    Caillot, T. Salama, Z.; Chanut, N.; Cadete Santos Aires, F.J.; Bennici, S.; Auroux, A.

    2013-07-15

    In this work, three equimolar mixed oxides ZrO{sub 2}/CeO{sub 2}, ZrO{sub 2}/TiO{sub 2}, ZrO{sub 2}/La{sub 2}O{sub 3} and a reference ZrO{sub 2} have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH{sub 3} and SO{sub 2} probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO{sub 2}/TiO{sub 2} material appears to be the best candidate for further application in acid–base catalysis. - Graphical abstract: Mesoporous amorphous phase with a high surface area of titania zirconia mixed oxide obtained by hydrothermal preparation. - Highlights: • Three zirconia based catalysts and a reference were prepared by hydrothermal synthesis. • Mixed oxides present larger surface areas than the reference ZrO{sub 2}. • ZrO{sub 2}/TiO{sub 2} catalyst presents a mesoporous structure with high surface area. • ZrO{sub 2}/TiO{sub 2} catalyst presents simultaneously strong acidic and basic properties.

  13. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  14. What Is in Your Zirconia?

    PubMed

    Helvey, Gregg A

    2017-04-01

    The immense popularity of zirconia as an indirect restorative material in dentistry has led to seemingly countless numbers of companies selling zirconia discs and blocks. The reliability of zirconia, however, is subject to specific manufacturing and processing protocols. Thus, it is of paramount importance for any dental professional utilizing zirconia to be aware of the source of the material and the various factors that can affect the success or failure of a final restoration. This article discusses the journey of zirconia, from being found among the elements of the earth to being placed in the patient's mouth. It also touches on drawbacks, such as translucency, associated with zirconia.

  15. Mesoporous ZrO2 fibers with enhanced surface area and the application as recyclable absorbent

    NASA Astrophysics Data System (ADS)

    Yu, Zhichao; Liu, Benxue; Zhou, Haifeng; Feng, Cong; Wang, Xinqiang; Yuan, Kangkang; Gan, Xinzhu; Zhu, Luyi; Zhang, Guanghui; Xu, Dong

    2017-03-01

    Highly crystalline mesoporous zirconia fibers with high surface area have been prepared by the use of electrospinning combined with precursors method. The obtained precursor fibers were treated in water steam and directly in air at different temperature respectively. Compared with the direct calcination in air, the water steam cannot only promote the crystallization of ZrO2 but also effectively remove off the organics and prevent the pore structure collapse. Moreover, through adding hydrochloric acid to modify the solution pH value, the obtained t-ZrO2 fibers treated in water steam at 300 °C have high surface area and large pore volume of 232.70 m2 g-1 and 0.36 cm3 g-1. The formation mechanism of the mesostucture was studied and the schematic was represented. Compared with the previous reports of mesoporous ZrO2 fibers, the as-synthesized materials exhibited the high crystallinity, large surface area and the long-range order mesostructure.The adsorption of Congo red indicates that the samples have a high adsorption capacity of 103.46 mg g-1 and long-periodic repeated availability.

  16. The effect of zirconia thickness on the biaxial flexural strength of zirconiaceramic bilayered discs.

    PubMed

    Sinmazisik, Gulden; Tarcin, Bilge; Demirbas, Bulent; Gulmez, Turgut; Bor, Emire; Ozer, Fusun

    2015-01-01

    The aim of this study was to assess the effect of zirconia core thickness on the biaxial flexural strength values of zirconia-porcelain bilayered discs. A total of 60 discs with 0.3, 0.4, and 0.5 mm thickness were obtained from a fully sintered zirconia block. A 1.5-mm thick layer of veneer porcelain was fired on the zirconia specimens and biaxial flexural strength tests were performed on the bilayered discs. In each group, the loading surface was the veneer porcelain in half of the specimens (core in tension) and the zirconia core surface in the other half (core in compression). The zirconia core thickness had no effect on the biaxial flexural strength of zirconiaporcelain bilayered discs when the core was in tension (p>0.05). Whereas, when the core was in compression, an increase in the zirconia core thickness resulted in an increase in the biaxial flexural strength (p<0.05).

  17. Direct silanization of zirconia for increased biointegration.

    PubMed

    Caravaca, Carlos; Shi, Liu; Balvay, Sandra; Rivory, Pascaline; Laurenceau, Emmanuelle; Chevolot, Yann; Hartmann, Daniel; Gremillard, Laurent; Chevalier, Jérôme

    2016-12-01

    High-performance bioinert ceramics such as zirconia have been used for biomedical devices since the early seventies. In order to promote osseointegration, the historical solution has been to increase the specific surface of the implant through roughness. Nevertheless these treatments on ceramics may create defects at the surface, exposing the material to higher chances of early failure. In zirconia, such treatments may also affect the stability of the surface. More recently, the interest of improving osseointegration of implants has moved the research focus towards the actual chemistry of the surface. Inspired by this, we have adapted the current knowledge and techniques of silica functionalization and applied it to successfully introduce 3-aminopropyldimethylethoxy silane (APDMES) directly on the surface of zirconia (3Y-TZP). We used plasma of oxygen to clean the surface and promote hydroxylation of the surface to increase silane density. The samples were extensively characterized by means of X-ray photoelectron spectroscopy (XPS) and contact angle, mechanically tested and its cytotoxicity was evaluated through cell adhesion and proliferation tests. Additionally, aging was studied to discard negative effects of the treatment on the stability of the tetragonal phase. No adverse effect was found on the mechanical response of treated samples. In addition, plasma-treated samples exhibited an unexpectedly higher resistance to aging. Finally, silane density was 35% lower than the one reported in literature for silica. However cells displayed a qualitatively higher spreading in opposition to the rounder appearance of cells on untreated zirconia. These results lay the foundations for the next generation of zirconia implants with biologically friendlier surfaces.

  18. Calculating landscape surface area from digital elevation models

    Treesearch

    Jeff S. Jenness

    2004-01-01

    There are many reasons to want to know the true surface area of the landscape, especially in landscape analysis and studies of wildlife habitat. Surface area provides a better estimate of the land area available to an animal than planimetric area, and the ratio of this surface area to planimetric area provides a useful measure of topographic roughness of the landscape...

  19. Zirconia: Established facts and perspectives for a biomaterial in dental implantology.

    PubMed

    Hisbergues, Michael; Vendeville, Sophie; Vendeville, Philippe

    2009-02-01

    Currently, zirconia is widely used in biomedical area as a material for prosthetic devices because of its good mechanical and chemical properties. Largely employed in clinical area for total hip replacement, zirconia ceramics (ZrO(2)) are becoming a prevalent biomaterial in dentistry and dental implantology. Although titanium is used in dental implantology currently, there is a trend to develop new ceramic-based implants as an alternative to monolithic titanium. This article reviews the evolution and development of zirconia through data published between 1963 and January 2008 in English language. Articles were identified via a MEDLINE search using the following keywords: zirconia, zirconia/biocompatibility, zirconia/osseointegration, zirconia/periointegration, zirconia/review, and zirconia/bacterial adhesion or colonization. This review of the literature aims at highlighting and discussing zirconia properties in biological systems for their future use in dental implantology. In conclusion, zirconia with its interesting microstructural properties has been confirmed to be a material of choice for the "new generation" of implants, thanks to its biocompatibility, osseoconductivity, tendency to reduce plaque accumulation, and interaction with soft tissues, which leads to periointegration. However, scientific studies are promptly needed to fulfill gaps like long-term clinical evaluations of "all zirconia implants," currently leading to propose an alternative use of "hybrid systems" (i.e., titanium screw with zirconia collar) and also bacterial colonization of zirconia. Moreover, there is a permanent need for consistent information about topography and chemistry of zirconia allowing easier cross-product comparisons of clinical devices. Copyright 2008 Wiley Periodicals, Inc.

  20. Zirconia solubility in boroaluminosilicate glass

    SciTech Connect

    Raman, S.V.; Bopp, R.; Batcheller, T.A.; Yan, Q.

    1995-12-31

    In the Idaho Chemical Processing Plant (ICPP) waste streams, zirconia is often the waste load limiting species. It modifies the glass network, enhances durability, increases viscosity and induces crystallization. The limits of its dissolution in boroaluminosilicate glass, with magnesia and soda additions were experimentally determined. A ternary compositional surface is evolved to present the isothermal regimes of liquid, liquid + zircon, liquid + forsterite, and liquid phase sintered ceramic. The potential of partitioning the transuranics, transition elements and solutes in these regimes is discussed. The visible Raman spectroscopic results are presented to elucidate the dependence among glass composition, structure and chemical durability.

  1. Surface and grain boundary energy as the key enabler of ferroelectricity in nanoscale hafnia-zirconia: a comparison of model and experiment.

    PubMed

    Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Schenk, Tony; Lee, Woongkyu; Kim, Keum Do; Fengler, Franz P G; Mikolajick, Thomas; Schroeder, Uwe; Hwang, Cheol Seong

    2017-07-20

    The unexpected ferroelectric properties of nanoscale hafnia-zirconia are considered to be promising for a wealth of applications including ferroelectric memory, field effect transistors, and energy-related applications. However, the reason why the unexpected ferroelectric Pca21 phase can be stabilized has not been clearly understood although numerous extensive theoretical and experimental results have been reported recently. The ferroelectric orthorhombic phase is not a stable phase under processing conditions from the viewpoint of bulk free energy. Although the possibility of stabilization of the ferroelectric phase due to the surface energy effect has been theoretically suggested, such a theoretical model has not been systematically compared with actual experimental results. In this study, the experimental observations on polymorphism in nanoscale HfO2-ZrO2 solid solution thin films of a wide range of film compositions and thicknesses are comprehensively related to the theoretical predictions based on a thermodynamic surface energy model. The theoretical model can semi-quantitatively explain the experimental results on the phase-evolution, but there were non-negligible discrepancies between the two results. To understand these discrepancies, various factors such as the film stress, the role of a TiN capping layer, and the kinetics of crystallization are systematically studied. This work also reports on the evolution of electrical properties of the film, i.e. dielectric, ferroelectric, anti-ferroelectric, and morphotropic phase changes, as a function of the film composition and thickness. The in-depth analyses of the phase change are expected to provide an important guideline for subsequent studies.

  2. Metal stain on monolithic zirconia restoration: A case report

    PubMed Central

    2017-01-01

    In restorative treatment using fixed dental prostheses, dentists should select appropriate restoration material among various types of dental materials. The strength, marginal fit, esthetics, wear resistance, biocompatibility, and cost are important factors in the choice of restoration materials. The present case showed a surface stain on a monolithic zirconia restoration that was due to wear between the monolithic zirconia restoration and the base metal alloy restoration. This phenomenon was confirmed by surface roughness measurement and electron probe micro-analysis. PMID:28435624

  3. Metal stain on monolithic zirconia restoration: A case report.

    PubMed

    Cha, Min-Sang; Lee, Sang-Woon; Huh, Yoon-Hyuk; Cho, Lee-Ra; Park, Chan-Jin

    2017-04-01

    In restorative treatment using fixed dental prostheses, dentists should select appropriate restoration material among various types of dental materials. The strength, marginal fit, esthetics, wear resistance, biocompatibility, and cost are important factors in the choice of restoration materials. The present case showed a surface stain on a monolithic zirconia restoration that was due to wear between the monolithic zirconia restoration and the base metal alloy restoration. This phenomenon was confirmed by surface roughness measurement and electron probe micro-analysis.

  4. Zirconia: cementation of prosthetic restorations. Literature review

    PubMed Central

    GARGARI, M.; GLORIA, F.; NAPOLI, E.; PUJIA, A.M.

    2011-01-01

    SUMMARY Aim of the work Aim of the work was to execute a review of the international literature about the cementation of zirconia restorations, analyzing the properties of the cements most commonly used in clinical activities. Materials and methods It was performed, through PubMed, a bibliographic search on the international literature of the last 10 years using the following limits: studies in English, in vitro studies, randomized clinical trial, reviews, meta-analysis, guide-lines. Were excluded from the search: descriptive studies, case reports, discussion articles, opinion’s leader. Results From studies results that common surface treatments (silanization, acid etching) are ineffective on zirconia because it has an inert surface without glassy component (on which this surface treatments act primarily), instead the sandblasting at 1atm with aluminium oxide (Al2O3) results significantly effective for the resulting roughening that increase the surface energy and the wettability of the material. Furthermore it has been shown that zinc phosphate-based cements, Bis-GMA-based and glass-ionomer cements can’t guarantee a stable long-term adhesion, instead resin cements containing phosphate monomer 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) have shown higher adhesion and stability values than the other cements. In particular, it has seen that bond strength of zirconia copings on dentin, using MDP-based cement, is about 6,9MPa; this value is comparable to that obtained with gold copings cementation. Conclusions Analyzed studies have led to the following conclusions: sandblasting with aluminium oxide (Al2O3) is the best surface treatment to improve adhesion between resin cements and zirconia; resin cements containing phosphate ester monomers 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) have shown in the studies an higher bond strength and stability after ageing treatment; the best procedure for cementing zirconia restorations results the combination of

  5. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    PubMed

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified.

  6. Characterization of surface runoff in urban areas.

    PubMed

    Choe, J S; Bang, K W; Lee, J H

    2002-01-01

    Water quality measurements of surface runoff have been carried out in selected residential and industrial zones in urban areas, in which yearly mean precipitation is 1,225 mm. The concentrations of constituents in the surface runoff were measured at sampling sites categorized by land use type in the residential zone, and by industry type in the industrial zone. The water quality constituents of BOD5, COD, SS, NO3-N, TKN, PO4-P, TP, n-Hexane extracts, Cr, Cu, Pb and Fe were analyzed. The event mean concentrations (EMCs) of COD, SS, TKN and TP in the residential zone were 313 mg/L, 279 mg/L, 8.45 mg/L, 1.98 mg/L, and those in the industrial zone were 80 mg/L, 106 mg/L, 5.07 mg/L, and 1.93 mg/L, respectively. Cumulative load curves were created to analyze the first-flushing effect of each pollutant related to the pollutant, the rainfall event, and the land use type. No general relationship between the cumulative load and runoff has been established. The degree of first-flushing effect by constituents was in the following order; TKN>COD>SS>HEM>TP>PO4-P. The correlations between SS and other constituents were analyzed to evaluate the efficiency of the physical treatment process to control the surface runoff in urban areas. Based on the correlation of constituents with SS, high treatment efficiency of SS, heavy metals, organic matter, and TP was expected. The unit pollutant loading rates of COD, SS, TKN, TP, Cr and Pb in the residential zone were 2,392, 2,130, 64.6, 15.1, 0.31, and 1.83 kg/ha/yr, and those in the industrial zone were 612, 812, 38.7, 14.8, 0.51 and 0.82 kg/ha/yr, respectively.

  7. On semiautomatic estimation of surface area.

    PubMed

    Dvořák, J; Jensen, E B V

    2013-05-01

    In this paper, we propose a semiautomatic procedure for estimation of particle surface area. It uses automatic segmentation of the boundaries of the particle sections and applies different estimators depending on whether the segmentation was judged by a supervising expert to be satisfactory. If the segmentation is correct the estimate is computed automatically, otherwise the expert performs the necessary measurements manually. In case of convex particles we suggest to base the semiautomatic estimation on the so-called flower estimator, a new local stereological estimator of particle surface area. For convex particles, the estimator is equal to four times the area of the support set (flower set) of the particle transect. We study the statistical properties of the flower estimator and compare its performance to that of two discretizations of the flower estimator, namely the pivotal estimator and the surfactor. For ellipsoidal particles, it is shown that the flower estimator is equal to the pivotal estimator based on support function measurements along four perpendicular rays. This result makes the pivotal estimator a powerful approximation to the flower estimator. In a simulation study of prolate and oblate ellipsoidal particles, the surfactor also performs well for particles which are not extremely elongated. In particular, the surfactor is not very much affected by the singularity in the surfactor formula or by possible inaccuracies in the necessary angle measurements. We also assess the performance of the semiautomatic procedure in a study of somatostatin positive inhibitory interneurons from mice hippocampi. Only 35% of the cells needed to be analysed manually and an important decrease in workload was obtained by using the semiautomatic approach. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

  8. Nonhydrolytic sol-gel approach to facile creation of surface-bonded zirconia organic-inorganic hybrid coatings for sample preparation. Ι. Capillary microextraction of catecholamine neurotransmitters.

    PubMed

    Alhendal, Abdullah; Mengis, Stephanie; Matthews, Jacob; Malik, Abdul

    2016-10-14

    Nonhydrolytic sol-gel (NHSG) route was used for the creation of novel zirconia-polypropylene oxide (ZrO2-PPO) sol-gel hybrid sorbents in the form of surface coatings for the extraction and preconcentration of catecholamine neurotransmitters and molecules structurally related to their deaminated metabolites. In comparison to other sorbents made of inorganic transition metal oxides, the presented hybrid organic-inorganic sorbents facilitated reversible sorption properties that allowed for efficient desorption of the extracted analytes by LC-MS compatible mobile phases. The presented sol-gel hybrid sorbents effectively overcame the major drawbacks of traditional silica- or polymer-based sorbents by providing superior pH stability (pH range: 0-14), and a variety of intermolecular interactions. Nonaqueous sol-gel treatment of PPO with ZrCl4 was employed for the derivatization of the terminal hydroxyl groups on PPO, providing zirconium trichloride-containing end groups characterized by enhanced sol-gel reactivity. NHSG ZrO2-PPO sorbent provided excellent microextraction performance for catecholamines, low detection limits (5.6-9.6pM), high run-to-run reproducibility (RSD 0.6-5.1%), high desorption efficiency (95.0-99.5%) and high enrichment factors (∼1480-2650) for dopamine and epinephrine, respectively, extracted from synthetic urine samples. The presented sol-gel sorbents provided effective alternative to conventional extraction media providing unique physicochemical characteristics and excellent extraction capability. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Zirconia implant abutments: microstructural analysis.

    PubMed

    Vaquero-Aguilar, Cristina; Jiménez-Melendo, Manuel; Torres-Lagares, Daniel; Llena-Blasco, Oriol; Bruguera, August; Llena-Blasco, Jaime; García-Calderón, Manuel; Velázquez-Cayón, Rocío; Gutiérrez-Pérez, José-Luis

    2012-01-01

    Yttria-stabilized zirconia (ZrO₂-Y₂O₃) ceramics have received increasing attention in recent years because of their stress-induced tetragonal-to-monoclinic (martensitic) transformation. This unique process acts as a toughening mechanism, imparting strength and toughness to the ceramic alloy. This property, along with well-documented biocompatibility, is now being exploited in an increasing number of medical applications, including implant dentistry. To prevent clinical problems and predict their behavior and physical limitations, a characterization of the ceramic elements used in dental restorations is essential. The aim of the present study is to characterize the crystal structure, elemental composition, and micr ostructure of asreceived ZiReal Post (Biomet 3i) zirconium oxide abutments, as well as specimens coated with a first layer of a low-fusing fluoroapatite ceramic. Zirconium oxide abutments, both as-received and porcelain-coated, were studied using the following techniques: x-ray diffraction, x-ray fluorescence, energy dispersive x-ray spectroscopy, optical microscopy, and scanning and transmission electron microscopy. X-ray analyses detected only the presence of Zr, O, Y, and hafnium (Hf), in an amount of 3% to 4% molecular weight Y₂O₃-ZrO₂. X-ray diffraction measurements showed that the ceramic abutment crystallizes mainly in the tetragonal phase, with some residual monoclinic phase. The microstructure is characterized by a rather homogenous grain distribution, formed by equiaxed and fine grains with a mean size of 0.30 Μm. Compositional and diffraction results are consistent with polycrystalline yttria-stabilized tetragonal zirconia. The material is susceptible to undergoing the stress-induced transformation toughening mechanism because of the very fine grain size. Except for machining ring marks, the surfaces exhibit an excellent finishing quality. No structural modifications were observed in the fluoroapatite ceramic-coated abutments

  10. Surface analysis and shear bond strength of zirconia on resin cements after non-thermal plasma treatment and/or primer application for metallic alloys.

    PubMed

    Vechiato-Filho, Aljomar José; Matos, Adaias Oliveira; Landers, Richard; Goiato, Marcelo Coelho; Rangel, Elidiane Cipriano; De Souza, Grace Mendonça; Barão, Valentim Adelino Ricardo; Dos Santos, Daniela Micheline

    2017-03-01

    There is no established protocol for bonding zirconia (Y-TZP) with resin cements. Non-thermal plasma (NTP) may be an alternative for the clinical problems related to adhesion. The purpose of the present study was to characterize the surface of Y-TZP exposed to methane (CH4) NTP or coated with a layer of primer for metal alloys and the association between the two methods and to evaluate the effect of NTP treatment on bond strength between Y-TZP and two resin cements. A total of 235 Y-TZP discs (8×2mm) were distributed into five groups: Co (no surface treatment), Pr (primer), NTP (methane plasma), Pr+NTP and NTP+Pr. The effect of the treatment type on the surface free energy, morphology, topography and chemical composition of the Y-TZP discs was investigated. The discs were cemented to composite resin substrates using Panavia F2.0 or RelyX U200. Shear bond strength (n=10) analyses were performed (1mm/min) before and after thermocycling (5-55°C, 2000cycles) on the bonded specimens. The data were analyzed with one and three-way ANOVAs and Bonferroni tests (α=0.05). NTP reduced the surface energy and roughness of the Y-TZP discs. SEM-EDS and XPS analyses showed the presence of the organic thin film, which significantly improved the bond strength results when Rely X U200 was used, whereas the primer treatment was more effective with Panavia F2.0. Thermocycling significantly reduced the bond strength results of the NTP and Pr+NTP groups cemented with Rely X U200 and the Pr and NTP+Pr groups cemented with Panavia F2.0. Nonthermal plasma improves the bond strength between Rely X U200 and Y-TZP and also seems to have water-resistant behavior, whereas Panavia F2.0 showed better results when associated with primer.

  11. Accessible surface area from NMR chemical shifts.

    PubMed

    Hafsa, Noor E; Arndt, David; Wishart, David S

    2015-07-01

    Accessible surface area (ASA) is the surface area of an atom, amino acid or biomolecule that is exposed to solvent. The calculation of a molecule's ASA requires three-dimensional coordinate data and the use of a "rolling ball" algorithm to both define and calculate the ASA. For polymers such as proteins, the ASA for individual amino acids is closely related to the hydrophobicity of the amino acid as well as its local secondary and tertiary structure. For proteins, ASA is a structural descriptor that can often be as informative as secondary structure. Consequently there has been considerable effort over the past two decades to try to predict ASA from protein sequence data and to use ASA information (derived from chemical modification studies) as a structure constraint. Recently it has become evident that protein chemical shifts are also sensitive to ASA. Given the potential utility of ASA estimates as structural constraints for NMR we decided to explore this relationship further. Using machine learning techniques (specifically a boosted tree regression model) we developed an algorithm called "ShiftASA" that combines chemical-shift and sequence derived features to accurately estimate per-residue fractional ASA values of water-soluble proteins. This method showed a correlation coefficient between predicted and experimental values of 0.79 when evaluated on a set of 65 independent test proteins, which was an 8.2 % improvement over the next best performing (sequence-only) method. On a separate test set of 92 proteins, ShiftASA reported a mean correlation coefficient of 0.82, which was 12.3 % better than the next best performing method. ShiftASA is available as a web server ( http://shiftasa.wishartlab.com ) for submitting input queries for fractional ASA calculation.

  12. Comparison of surface modified zirconia implants with commercially available zirconium and titanium implants: a histological study in pigs.

    PubMed

    Gredes, Tomasz; Kubasiewicz-Ross, Pawel; Gedrange, Tomasz; Dominiak, Marzena; Kunert-Keil, Christiane

    2014-08-01

    New biomaterials and their various surface modifications should undergo in vitro and in vivo evaluation before clinical trials. The objective of our in vivo study was to evaluate the biocompatibility of newly created zirconium implant surfaces after implantation in the lower jaw of pigs and compare the osseointegration of these dental implants with commercially available zirconium and titanium implants. After a healing period of 12 weeks, a histological analysis of the soft and hard tissues and a histomorphometric analysis of the bone-implant contact (BIC) were performed. The implant surfaces showed an intimate connection to the adjacent bone for all tested implants. The 3 newly created zirconium implant surfaces achieved a BIC of 45% on average in comparison with a BIC of 56% from the reference zirconium implants and 35% from titanium implants. Furthermore, the new zirconium implants had a better attachment to gingival and bone tissues in the range of implant necks as compared with the reference implants. The results suggest that the new implants comparably osseointegrate within the healing period, and they have a good in vivo biocompatibility.

  13. Histologic and histomorphometric behavior of microgrooved zirconia dental implants with immediate loading.

    PubMed

    Delgado-Ruiz, Rafael Arcesio; Calvo-Guirado, Jose Luis; Abboud, Marcus; Ramirez-Fernandez, Maria Piedad; Maté-Sánchez de Val, José Eduardo; Mate-Sanchez, Jose Eduardo; Negri, Bruno; Rothamel, Daniel

    2014-12-01

    The study aims to assess the total soft tissue (ST) width, crestal bone level (CBL), bone-to-implant contact (BIC), and bone density (BD) for zirconia implants textured with microgrooved surfaces and immediately loaded. This study included 51 implants; one implant from each study group was retained for surface characterization. The 48 remaining implants were inserted randomly in premolar areas of both sides of the healed edentulous lower jaws of foxhound dogs. They were divided into three groups of 16: control (titanium); test A (zirconia), and test B (microgrooved zirconia). The implants were splinted and covered with an acrylic bridge. A split-mouth design was used and immediate occlusal loading was applied on one side, while the other side did not have occlusal contact. ST, CBL, BIC, and BD were evaluated after 3 months. The effects of immediate loading on these parameters were analyzed. All the implants were osseointegrated. ST was established at 3 months with mean values of 2.9 ± 0.4 mm for all groups. No differences were appreciated between loaded and unloaded sides regarding ST (p > .05). CBL showed a mean of 1.2 ± 0.3 mm for all groups without differences between loaded and unloaded sides (p > .05). BIC percentages were significantly higher for loaded all-microgrooved implants (p < .05). BD percentages were higher in areas close to all-microgrooved implants (p < .05) and significantly higher for loaded implants than unloaded. Within the limitations of the present study, it may be concluded that for zirconia dental implants with microgrooved surfaces and immediate loading, the thickness of STs remains stable resulting in 3 mm mean biologic width, that crestal bone preservation is related to insertion depth, and that higher BIC percentages and increased BD around implants microgrooved over the entire intraosseous area may be expected at 3 months following implant insertion and immediate loading. © 2013 Wiley Periodicals, Inc.

  14. Damage areas on selected LDEF aluminum surfaces

    NASA Technical Reports Server (NTRS)

    Coombs, Cassandra R.; Atkinson, Dale R.; Allbrooks, Martha K.; Watts, Alan J.; Hennessy, Corey J.; Wagner, John D.

    1993-01-01

    With the U.S. about to embark on a new space age, the effects of the space environment on a spacecraft during its mission lifetime become more relevant. Included among these potential effects are degradation and erosion due to micrometeoroid and debris impacts, atomic oxygen and ultraviolet light exposure as well as material alteration from thermal cycling, and electron and proton exposure. This paper focuses on the effects caused by micrometeoroid and debris impacts on several LDEF aluminum plates from four different bay locations: C-12, C-10, C-01, and E-09. Each plate was coated with either a white, black, or gray thermal paint. Since the plates were located at different orientations on the satellite, their responses to the hypervelocity impacts varied. Crater morphologies range from a series of craters, spall zones, domes, spaces, and rings to simple craters with little or no spall zones. In addition, each of these crater morphologies is associated with varying damage areas, which appear to be related to their respective bay locations and thus exposure angles. More than 5% of the exposed surface area examined was damaged by impact cratering and its coincident effects (i.e., spallation, delamination and blow-off). Thus, results from this analysis may be significant for mission and spacecraft planners and designers.

  15. Surface characterization of zirconia-coated tungsten Schottky emitters by using RHEED, AES, and TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Matsunaga, Soichiro; Katagiri, Souichi

    2015-03-01

    Temperature dependences of surface periodicity on the Zr/O/W(100) and (110) of a Schottky emitter tip have been directly measured by RHEED equipment improved by installing a heating stage and an imaging system. Reversible structural change from c(2× 4) + c(4 × 2) to p(1 × 1) has been observed only in (100). Bonding states of Zr-O, Zr-W, and O-W on Zr/O/W(100), (110), and (112) in planar-samples have been evaluated by AES and TOF-SIMS. We propose a structural model of a Zr/O/W surface in which Zr atoms are adsorbed on O atoms in W-O layers formed on the W single crystal.

  16. Comparison of alternative adhesive cementation concepts for zirconia ceramic: glaze layer vs zirconia primer.

    PubMed

    Cura, Cenk; Özcan, Mutlu; Isik, Gül; Saracoglu, Ahmet

    2012-02-01

    Zirconia-based ceramics offer strong restorations in dentistry, but the adhesive bond strength of resin cements to such ceramics is not optimal. This study evaluated the bond strength of silane/adhesive/resin cement and zirconia primer/resin cement combinations on non-glazed and glazed zirconia surfaces before and after aging. Disk-shaped zirconia ceramic specimens (diameter: 8 mm; thickness: 2 mm) (N = 80, n = 10 per group) were randomly divided into 2 groups. While half of the specimens received one coat of glaze and were later finished by grinding, the other half was only ground using 1200-grit silicone carbide abrasives under water. The glazed specimens were then conditioned with 9.5% HF acid gel for 60 s, rinsed with water for 90 s, and neutralized. The glazed and non-glazed specimens were further divided into two groups. Two resin cements, namely, Variolink II and Multilink Automix were adhered onto the zirconia surfaces with their corresponding adhesive systems. In the Variolink II group, zirconia surfaces were silanized (Monobond-S), and adhesive resin (Heliobond) was applied and photopolymerized. In the Multilink Automix group, one coat of Metal/Zirconia Primer was applied with a microbrush, left to react for 180 s, and dried using oil-free air. Half of the specimens in each cement group were subjected to 5000 thermocycles (5°C to 55°C) and the other half was kept in the dark for 24 h at 37°C prior to testing. Specimens were mounted in the jig of the universal testing machine, and force was applied to the ceramic/cement interface until failure occurred (1 mm/min). After evaluating all debonded specimens under SEM, the failure types were defined as either "adhesive" with no cement left on the zirconia (score 0) or "mixed" with less than half of the cement left on the surface with no cohesive failure of the substrate (score 1). Data were analyzed using three-way ANOVA and Dunnett-T3 post-hoc tests. Application of a glaze layer significantly improved the

  17. Fusion sputtering for bonding to zirconia-based materials.

    PubMed

    Aboushelib, Moustafa N

    2012-08-01

    To evaluate the influence of fusion sputtering on zirconia-resin microtensile bond strength after 6 months of water storage. Zirconia disks received one of the following surface treatments: particle abrasion with 50-µm aluminum oxide particles or fusion sputtering, while as-sintered specimens served as a control. The prepared zirconia disks (Lava Zirconia) were bonded to pre-aged composite disks (Filtek Z250) using a phosphatemonomer- containing resin cement (RelyX Unicem), and the bonded specimens were sectioned into micro-bars (1 x 1 x 6 mm) which were either immediately tested or after 6 months of water storage (n = 25). Scanning electron microscopy (SEM) and surface roughness were performed for the prepared specimens. Data were analyzed using two-way ANOVA (α = 0.05). Particle abrasion (33.1 MPa) and fusion sputtering (42.5 MPa) produced significantly higher MTBS values and resisted degradation after 6 months of water storage, while as-sintered specimens (12.4 MPa) demonstrated a significant reduction in bond strength after water storage (2.9 MPa). SEM examination indicated that fusion sputtering resulted in the creation of retentive zirconia beads on the treated surface, which enhanced micromechanical retention with adhesive resin and prevented interfacial failure. Fusion sputtering is a new and a simple method suitable for enhancing the bond strength of adhesive resins to zirconia-based frameworks.

  18. Body surface area formulae: an alarming ambiguity.

    PubMed

    Redlarski, Grzegorz; Palkowski, Aleksander; Krawczuk, Marek

    2016-06-21

    Body surface area (BSA) plays a key role in several medical fields, including cancer chemotherapy, transplantology, burn treatment and toxicology. BSA is often a major factor in the determination of the course of treatment and drug dosage. A series of formulae to simplify the process have been developed. Because easy-to-identify, yet general, body coefficient results of those formulae vary considerably, the question arises as to whether the choice of a particular formula is valid and safe for patients. Here we show that discrepancies between most of the known BSA formulae can reach 0.5 m(2) for the standard adult physique. Although many previous studies have demonstrated that certain BSA formulae provide an almost exact fit with the patients examined, all of these studies have been performed on a limited and isolated group of people. Our analysis presents a broader perspective, considering 25 BSA formulae. The analysis revealed that the choice of a particular formula is a difficult task. Differences among calculations made by the formulae are so great that, in certain cases, they may considerably affect patients' mortality, especially for people with an abnormal physique or for children.

  19. Body surface area formulae: an alarming ambiguity

    PubMed Central

    Redlarski, Grzegorz; Palkowski, Aleksander; Krawczuk, Marek

    2016-01-01

    Body surface area (BSA) plays a key role in several medical fields, including cancer chemotherapy, transplantology, burn treatment and toxicology. BSA is often a major factor in the determination of the course of treatment and drug dosage. A series of formulae to simplify the process have been developed. Because easy-to-identify, yet general, body coefficient results of those formulae vary considerably, the question arises as to whether the choice of a particular formula is valid and safe for patients. Here we show that discrepancies between most of the known BSA formulae can reach 0.5 m2 for the standard adult physique. Although many previous studies have demonstrated that certain BSA formulae provide an almost exact fit with the patients examined, all of these studies have been performed on a limited and isolated group of people. Our analysis presents a broader perspective, considering 25 BSA formulae. The analysis revealed that the choice of a particular formula is a difficult task. Differences among calculations made by the formulae are so great that, in certain cases, they may considerably affect patients’ mortality, especially for people with an abnormal physique or for children. PMID:27323883

  20. Synthesis of Yttria-Stabilized Zirconia Aerogels by a Non-Alkoxide Sol-Gel Route

    SciTech Connect

    Chervin, C N; Clapsaddle, B J; Chiu, H W; Gash, A E; Satcher, Jr., J H; Kauzlarich, S M

    2005-02-11

    Homogeneous, nanocrystalline powders of yttria-stabilized zirconia were prepared using a nonalkoxide sol-gel method. Monolithic gels, free of precipitation, were prepared by addition of propylene oxide to aqueous solutions of Zr{sup 4+} and Y{sup 3+} chlorides at room temperature. The gels were dried with supercritical CO{sub 2}(l), resulting in amorphous aerogels that crystallized into cubic stabilized ZrO{sub 2} following calcination at 500 C. The aerogels and resulting crystalline products were characterized using in-situ temperature profile X-ray diffraction, thermal analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. TEM and N{sub 2} adsorption/desorption analysis of an aerogel indicated a porous network structure with a high surface area (409 m{sup 2}/g). The crystallized yttria-stabilized zirconia maintained high surface area (159 m{sup 2}/g) upon formation of homogeneous, nanoparticles ({approx}10 nm). Ionic conductivity at 1000 C of sintered YSZ (1500 C, 3 hours) prepared by this method, was 0.13 {+-} 0.02 {Omega}{sup -1} cm{sup -1}. Activation energies for the conduction processes from 1000-550 C and 550-400 C, were 0.95 {+-} 0.09 and 1.12 {+-} 0.05 eV, respectively. This is the first reported synthesis and characterization of yttria-stabilized zirconia via an aerogel precursor.

  1. Resin bonding of metal brackets to glazed zirconia with a porcelain primer

    PubMed Central

    Lee, Jung-Hwan; Lee, Milim; Kim, Kyoung-Nam

    2015-01-01

    Objective The aims of this study were to compare the shear bond strength between orthodontic metal brackets and glazed zirconia using different types of primer before applying resin cement and to determine which primer was more effective. Methods Zirconia blocks were milled and embedded in acrylic resin and randomly assigned to one of four groups: nonglazed zirconia with sandblasting and zirconia primer (NZ); glazed zirconia with sandblasting, etching, and zirconia primer (GZ); glazed zirconia with sandblasting, etching, and porcelain primer (GP); and glazed zirconia with sandblasting, etching, zirconia primer, and porcelain primer (GZP). A stainless steel metal bracket was bonded to each target surface with resin cement, and all specimens underwent thermal cycling. The shear bond strength of the specimens was measured by a universal testing machine. A scanning electron microscope, three-dimensional optical surface-profiler, and stereoscopic microscope were used to image the zirconia surfaces. The data were analyzed with one-way analyses of variance and the Fisher exact test. Results Group GZ showed significantly lower shear bond strength than did the other groups. No statistically significant differences were found among groups NZ, GP, and GZP. All specimens in group GZ showed adhesive failure between the zirconia and resin cement. In groups NZ and GP, bonding failed at the interface between the resin cement and bracket base or showed complex adhesive and cohesive failure. Conclusions Porcelain primer is the more appropriate choice for bonding a metal bracket to the surface of a full-contour glazed zirconia crown with resin cement. PMID:26629476

  2. Orthodontic bracket bonding to glazed full-contour zirconia

    PubMed Central

    Kwak, Ji-Young; Jung, Hyo-Kyung; Choi, Il-Kyung

    2016-01-01

    Objectives This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods Glazed zirconia (except for the control, Zirkonzahn Prettau) disc surfaces were pre-treated: PO (control), polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z) or a silane primer (Monobond-S, S) was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S). Metal bracket-bonded specimens were stored in water for 24 hr at 37℃, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10). Results Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z (4.60 ± 1.08 MPa) and all other groups (13.38 ± 2.57 - 15.78 ± 2.39 MPa, p < 0.05). For AA-Z, most of the adhesive remained on the bracket. Conclusions For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed. PMID:27200278

  3. Efficacy of various cleaning solutions on saliva-contaminated zirconia for improved resin bonding

    PubMed Central

    Kim, Da-Hye; Son, Jun-Sik; Jeong, Seong-Hwa; Kim, Young-Kyung

    2015-01-01

    PURPOSE This study aimed to investigate the efficacy of cleaning solutions on saliva-contaminated zirconia in comparison to air-abrasion in terms of resin bonding. MATERIALS AND METHODS For saliva-contaminated airabraded zirconia, seven cleaning methods)-no contamination (NC), water-spray rinsing (WS), additional airabrasion (AA), and cleaning with four solutions (Ivoclean [IC]; 1.0 wt% sodium dodecyl sulfate [SDS], 1.0 wt% hydrogen peroxide [HP], and 1.0 wt% sodium hypochlorite [SHC])-were tested. The zirconia surfaces for each group were characterized using various analytical techniques. Three bonded resin (Panavia F 2.0) cylinders (bonding area: 4.5 mm2) were made on one zirconia disk specimen using the Ultradent jig method [four disks (12 cylinders)/group; a total of 28 disks]. After 5,000 thermocycling, all specimens were subjected to a shear bond strength test with a crosshead speed of 1.0 mm/minute. The fractured surfaces were observed using an optical and scanning electron microscope (SEM). RESULTS Contact angle measurements showed that groups NC, AA, IC, and SHC had hydrophilic surfaces. The X-ray photoelectron spectroscopy (XPS) analysis showed similar elemental distributions between group AA and groups IC and SHC. Groups IC and SHC showed statistically similar bond strengths to groups NC and AA (P>.05), but not groups SDS and HP (P<.05). For groups WS, SDS, and HP, blister-like bubble formations were observed on the surfaces under SEM. CONCLUSION Within the limitations of this in vitro study, some of the cleaning solutions (IC or SHC) were effective in removing saliva contamination and enhancing the resin bond strength. PMID:25932305

  4. Effect of hydrothermal treatment on light transmission of translucent zirconias.

    PubMed

    Putra, Armand; Chung, Kwok-Hung; Flinn, Brian D; Kuykendall, Tuesday; Zheng, Cheng; Harada, Kosuke; Raigrodski, Ariel J

    2017-09-01

    Studies of the light transmission of translucent zirconias after hydrothermal treatment are limited. The purpose of this in vitro study was to evaluate the effect of hydrothermal treatment on the light transmission of translucent zirconias for monolithic restorations. Four commercially available zirconia products, BruxZir Anterior Solid Zirconia (BruxAnt, BA), Lava Plus High Translucency (LPHT), Katana Zirconia Super Translucent (KST), and Katana Zirconia Ultra Translucent (KUT) were assessed and 1 type of lithium disilicate, e.max Press LT (LDLT) was used as a control. Plate specimens, 20×20×1 mm (n=80) for the translucency assessment were sectioned from postsintered zirconia bulk materials and ground with a #400-grit diamond wheel and coolant. The specimens were placed under hydrothermal conditions of 134°C at 0.2 MPa (n=5 per group at 0, 5, 50, and 100 hours). Percentage of total transmittance of light (Tt%) of each specimen was measured using a spectrophotometer with an integrating sphere. X-ray diffraction analyses were used to measure tetragonal-monoclinic phase transformation. Surfaces were examined by scanning electron microscopy and energy dispersive spectrometry. Data were analyzed using 2-way ANOVA followed by the Tukey test (α=.05). The Tt% ranged from 6.5% to 28.3%. Group LDLT obtained significantly higher transmittance than other tested groups, whereas groups KST and KUT had significantly higher Tt% than groups BA and LPHT (P<.05). A statistically significant increase in the amount of monoclinic phase was revealed within all translucent zirconia groups (P<.05), and the increase in group LPHT was significantly higher than those of the other 3 translucent zirconias (P<.05). Minimal changes in the percentages of light transmittance were revealed after 100-hour hydrothermal treatment for all tested translucent zirconias and a lithium disilicate glass-ceramic control. Hydrothermal treatment had minimal effects on the translucency of translucent

  5. Zirconia implant abutments: a review.

    PubMed

    Gomes, Ana-Luísa; Montero, Javier

    2011-01-01

    An increasing aesthetic demand within developed populations conducted to the fabrication of metal-free restorations and to a wide use of ceramic materials, due to its excellent characteristics of biocompatibility and aesthetics. With the incessant increase of commercial labels involved in this technological advance, a review is imposed on ceramic abutments, specifically on zirconia. We made a search of articles of peer-reviewed Journals in PubMed/Medline, crossing the terms "Dental Abutments", "Dental Porcelain" and "Zirconia". The review was divided by subtopics: zirconia physical and mechanical properties, precision fit in the implant-abutment interface, zirconia abutments strength and, finally, bacterial adherence and tissues response. Several studies demonstrate that zirconia abutments offer good results at all the levels but relevant issues need further studies and evaluation. One of the most important is the clinical long term success of zirconia abutments on implants, given that in the literature there are no sufficient in vivo studies that prove it.

  6. Effect of zirconia on the physicochemical properties of copper (II) imidazolate frameworks

    NASA Astrophysics Data System (ADS)

    Shaharun, Maizatul S.; Shaharun, Salina; Al-Shaibani, Asem

    2016-11-01

    Copper(II) bis(imidazolate) and copper(II)-zirconia(IV) bimetallic imidazolate were synthesized by metal oxides in aqueous solutions using acid catalyst procedure. The metal imidazolate frameworks were characterized by fourier transform infrared spectra (FTIR), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis) and N2 adsorption-desorption. The addition of ZrO2 increased the surface area and porosity of the metal organic frameworks. The modification of the copper(II) bis(imidazolate) with addition of ZrO2 enhances the visible light absorbance. The band gap of copper(II)-zirconia(II) bimetallic imidazolate is increased to 2.40 eV with more absorbance in the visible region compared to copper(II) bis(imidazolate).

  7. Sliding Contact Fatigue of Graded Zirconia with External Esthetic Glass

    PubMed Central

    Ren, L.; Janal, M.N.; Zhang, Y.

    2011-01-01

    Veneer chipping and fracture are common failure modes for porcelain-veneered zirconia dental restorations. We hypothesized that the graded glass/zirconia/glass with external esthetic glass (e-GZG) can increase the lifetime and improve resistance to veneer chipping and fracture relative to porcelain-veneered zirconia, while providing necessary esthetics. Previously, we have demonstrated that a graded glass-zirconia surface possesses excellent resistance to occlusal-like sliding contact fatigue. Here, we investigated the sliding contact fatigue response of this graded glass-zirconia surface with external esthetic glass. This external glass is essential for shade options, for preventing excessive wear of opposing dentition, and for protecting Y-TZP from hydrothermal degradation. e-GZG plates were bonded to composite blocks and subjected to prolonged sliding contact up to 10 million cycles at 200 N in water. The resistance to sliding contact fatigue of e-GZG matches that of monolithic Y-TZP, and both of these materials demonstrated lifetimes that were orders of magnitude longer than that of porcelain-veneered zirconia. Graded e-GZG is a promising restorative material. PMID:21666105

  8. Zirconia as a Dental Biomaterial.

    PubMed

    Bona, Alvaro Della; Pecho, Oscar E; Alessandretti, Rodrigo

    2015-08-04

    Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different substrates, which has offered a great challenge to dental zirconia research and development. This study characterizes zirconia as a dental biomaterial, presenting the current consensus and challenges to its dental applications.

  9. Mesoporous silica templated zirconia nanoparticles

    NASA Astrophysics Data System (ADS)

    Ballem, Mohamed A.; Córdoba, José M.; Odén, Magnus

    2011-07-01

    Nanoparticles of zirconium oxide (ZrO2) were synthesized by infiltration of a zirconia precursor (ZrOCl2·8H2O) into a SBA-15 mesoporous silica mold using a wet-impregnation technique. X-ray diffractometry and high-resolution transmission electron microscopy show formation of stable ZrO2 nanoparticles inside the silica pores after a thermal treatment at 550 °C. Subsequent leaching out of the silica template by NaOH resulted in well-dispersed ZrO2 nanoparticles with an average diameter of 4 nm. The formed single crystal nanoparticles are faceted with 110 surfaces termination suggesting it to be the preferred growth orientation. A growth model of these nanoparticles is also suggested.

  10. In Vitro Cell Proliferation and Mechanical Behaviors Observed in Porous Zirconia Ceramics

    PubMed Central

    Li, Jing; Wang, Xiaobei; Lin, Yuanhua; Deng, Xuliang; Li, Ming; Nan, Cewen

    2016-01-01

    Zirconia ceramics with porous structure have been prepared by solid-state reaction using yttria-stabilized zirconia and stearic acid powders. Analysis of its microstructure and phase composition revealed that a pure zirconia phase can be obtained. Our results indicated that its porosity and pore size as well as the mechanical characteristics can be tuned by changing the content of stearic acid powder. The optimal porosity and pore size of zirconia ceramic samples can be effective for the increase of surface roughness, which results in higher cell proliferation values without destroying the mechanical properties. PMID:28773341

  11. Surface atmospheric extremes (Launch and transportation areas)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The effects of extreme values of surface and low altitude atmospheric parameters on space vehicle design, tests, and operations are discussed. Atmospheric extremes from the surface to 150 meters for geographic locations of interest to NASA are given. Thermal parameters (temperature and solar radiation), humidity, pressure, and atmospheric electricity (lighting and static) are presented. Weather charts and tables are included.

  12. Nitrogen-doped zirconia: A comparison with cation stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Sook; Lerch, Martin; Maier, Joachim

    2006-01-01

    The conductivity behavior of nitrogen-doped zirconia is compared with that of zirconia doped with lower-valent cations and discussed in the framework of defect-defect interactions. While nominally introducing the same number of vacancies as yttrium, nitrogen dopants introduced in the anion sublattice of zirconia lead to substantially different defect kinetics and energetics. Compared to the equivalent yttrium doping nitrogen doping in the Y-Zr-O-N system substantially increases the activation energy and correspondingly decreases the conductivity at temperatures below 500C in the vacancy range below 4 mol%. The comparison of N-doped zirconia and zirconia systems doped with size-matched cation stabilizers, such as Sc, Yb and Y, shows that elastically driven vacancy-vacancy ordering interactions can phenomenologically account for the temperature- and composition-dependence. It is striking that materials with superior high-temperature conductivities due to weak dopant-vacancy interactions undergo severe deterioration at low temperature due to the strong vacancy-ordering. The analysis also explains qualitatively similar effects of Y co-doping in Yb-, Sc-, and N-doped zirconia. Small amount of Y in N-doped zirconia as well as in Sc-doped zirconia appears to hinder the formation of the long-range ordered phase and thus enhance the conductivity substantially.

  13. Nitrogen-doped zirconia: A comparison with cation stabilized zirconia

    SciTech Connect

    Lee, Jong-Sook . E-mail: jong-sook.lee@fkf.mpg.de; Lerch, Martin; Maier, Joachim

    2006-01-15

    The conductivity behavior of nitrogen-doped zirconia is compared with that of zirconia doped with lower-valent cations and discussed in the framework of defect-defect interactions. While nominally introducing the same number of vacancies as yttrium, nitrogen dopants introduced in the anion sublattice of zirconia lead to substantially different defect kinetics and energetics. Compared to the equivalent yttrium doping nitrogen doping in the Y-Zr-O-N system substantially increases the activation energy and correspondingly decreases the conductivity at temperatures below 500{sup -}bar C in the vacancy range below 4mol%. The comparison of N-doped zirconia and zirconia systems doped with size-matched cation stabilizers, such as Sc, Yb and Y, shows that elastically driven vacancy-vacancy ordering interactions can phenomenologically account for the temperature- and composition-dependence. It is striking that materials with superior high-temperature conductivities due to weak dopant-vacancy interactions undergo severe deterioration at low temperature due to the strong vacancy-ordering. The analysis also explains qualitatively similar effects of Y co-doping in Yb-, Sc-, and N-doped zirconia. Small amount of Y in N-doped zirconia as well as in Sc-doped zirconia appears to hinder the formation of the long-range ordered phase and thus enhance the conductivity substantially.

  14. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  15. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe...

  16. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Illumination of surface working areas. 56.17001... § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  17. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  18. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  19. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  20. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  1. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  2. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  3. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  4. Biaxial flexural strength of bilayered zirconia using various veneering ceramics

    PubMed Central

    Chantranikul, Natravee

    2015-01-01

    PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength. PMID:26576251

  5. Phase transformation of zirconia ceramics by hydrothermal degradation.

    PubMed

    Kawai, Yohei; Uo, Motohiro; Wang, Yongming; Kono, Sayaka; Ohnuki, Somei; Watari, Fumio

    2011-01-01

    Zirconia has found wide application in dentistry because of its high mechanical strength and superior esthetic properties. However, zirconia degradation caused by phase transformation occurring in a hydrothermal environment is of concern. In the present study, phase transformation and microstructure of tetragonal zirconia polycrystal partially stabilized with yttrium oxide (Y-TZP) and alumina-toughened zirconia (ATZ) sintered at different temperatures were estimated. On grazing angle X-ray diffraction analysis, ATZ showed less phase transformation to the monoclinic phase during hydrothermal treatment and this transformation appeared to occur within a few micrometers below the surface. At a higher sintering temperature the monoclinic phase content of ATZ was found to be lesser than that of Y-TZP, indicating that the alumina in ATZ was effective in suppressing hydrothermal degradation. Examination by transmission electron microscopy and studying of electron backscatter diffraction patterns indicated that grain growth in ATZ was slightly suppressed compared with that in Y-TZP at higher sintering temperatures. The present study demonstrated the effect of adding alumina to zirconia for suppressing hydrothermal degradation and studied the effect of this addition on grain growth in zirconia.

  6. 77 FR 50165 - Escape and Evacuation Plans for Surface Coal Mines, Surface Facilities and Surface Work Areas of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-20

    ... Safety and Health Administration Escape and Evacuation Plans for Surface Coal Mines, Surface Facilities and Surface Work Areas of Underground Coal Mines AGENCY: Mine Safety and Health Administration, Labor... surface coal mines, surface facilities and surface work areas of underground coal mines. MSHA is...

  7. Sintering additives for zirconia ceramics

    SciTech Connect

    Wu, S.

    1986-01-01

    This book is an overview of sintering science and its application to zirconia materials including CaO, MgO, and Y/sub 2/O/sub 3/-CeO/sub 2/ doped materials. This book is a reference for first-time exposure to zirconia materials technology, particularly densification.

  8. Surface area and travel time relationships in aquifer treatment systems.

    PubMed

    Fox, Peter; Makam, Roshan

    2009-11-01

    Soil aquifer treatment (SAT) and bank filtration use natural attenuation processes to purify water for subsequent use. Soil aquifer treatment may constitute both unsaturated and saturated flow conditions, while bank filtration systems are primarily saturated flow. This analysis focuses on the saturated zone, where the majority of residence time occurs, in both SAT and bank filtration systems. Sustainable removal mechanisms during subsurface flow are primarily surface-mediated and therefore depend on surface area. By analyzing saturated subsurface flow hydraulics in granular media, a relationship between surface area and travel time was developed. For saturated subsurface flow, the ratio of surface area-to-travel time varied by approximately a factor of 3, for common aquifer materials subject to identical hydraulic gradients. Because travel time criteria often are used to regulate SAT and bank filtration systems, these criteria also may determine the surface area and associated surface-mediated reactions for water purification. The ratio of surface area-to-travel time increases with increasing hydraulic gradient, implying that surface area is relatively constant for specific travel times, even if the hydraulic gradient changes; however, the increasing hydraulic gradient will increase the distance from the recharge zone to the recovery well. Therefore, travel time assessments based on maximum possible hydraulic gradients increase surface area and could provide a conservative limit for surface-mediated reactions. This analysis demonstrates that travel time criteria for SAT and bank filtration systems indirectly provide a minimum surface area that may support sustainable removal mechanisms.

  9. Shear bond strength of indirect composite material to monolithic zirconia.

    PubMed

    Sari, Fatih; Secilmis, Asli; Simsek, Irfan; Ozsevik, Semih

    2016-08-01

    This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia.

  10. Shear bond strength of indirect composite material to monolithic zirconia

    PubMed Central

    2016-01-01

    PURPOSE This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). MATERIALS AND METHODS Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). RESULTS Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). CONCLUSION Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia. PMID:27555895

  11. Acid etching of glass-infiltrated zirconia and its biological response.

    PubMed

    Vu, Van Thi; Oh, Gye-Jeong; Yun, Kwi-Dug; Lim, Hyun-Pil; Kim, Ji-Won; Nguyen, Thao Phuong Thi; Park, Sang-Won

    2017-04-01

    The purpose of this study was to evaluate the influence of acid etching treatment on surface characteristics and biological response of glass-infiltrated zirconia. A hundred zirconia specimens were divided into four groups depending on surface treatments: untreated zirconia (group Z); acid-etched zirconia (group ZE); glass-infiltrated zirconia (group ZG); and glass-infiltrated and acid-etched zirconia (group ZGE). Surface roughness, surface topography, surface morphology, and Vickers hardness of specimens were evaluated. For biological response test, MC3T3-E1 cell attachment and proliferation on surface of the specimens were examined. The data were statistically analyzed using one-way ANOVA and Tukey's HSD test at a significance level of 0.05. Group ZGE showed the highest surface roughness (Ra = 1.54 µm) compared with other groups (P < .05). Meanwhile, the hardness of group Z was significantly higher than those of other groups (P < .05). Cell attachment and cell proliferation were significantly higher in group ZGE (P < .05). We concluded that effective surface roughness on zirconia could be made by acid etching treatment after glass infiltration. This surface showed significantly enhanced osteoblast cell response.

  12. Surface atmospheric extremes (launch and transportation areas)

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Criteria are provided on atmospheric extremes from the surface to 150 meters for geographical locations of interest to NASA. Thermal parameters (temperature and solar radiation), humidity, precipitation, pressure, and atmospheric electricity (lightning and static) are presented. Available data are also provided for the entire continental United States for use in future space programs.

  13. Monolithic zirconia and digital impression: case report.

    PubMed

    De Angelis, F; Brauner, E; Pignatiello, G; Mencio, F; Rosella, D; Papi, P; Di Carlo, T; Giovannetti, A; Pompa, G; Di Carlo, S

    2017-01-01

    The aim of this study is to present a clinical case of a full arch prosthetic rehabilitation on natural teeth, combining both digital work-flow and monolithic zirconia. Digital impression was taken with an intraoral optical scanner (CS3500, Carestream Dental, Atlanta, GA, USA). A prosthetic rehabilitation was realized on natural teeth using monolithic zirconia from 1.6 to 1.4 and from 2.7 to 2.4 frameworks, while in the aesthetic area (from 2.3 to 1.3), technicians left on the structure a 0.8 mm vestibular space for ceramic layering. The combination of digital impression technology and the use of the monolithic zirconia had demonstrated the delivery of the final prosthetic device in a quick time without the need to remodel functional or aesthetic areas. The digital work-flow combines intraoral optical impression techniques and CAD/CAM technology, in order to achieve a fully digital and successful way to deliver prosthetic restorations to patients, providing aesthetics and function in shorter intervals of time. The clinical outcome of this study was satisfactory but a long-term evaluation is needed.

  14. Effect of zirconia on the physicochemical properties of Cu/ZnO/Al2O3 catalyst

    NASA Astrophysics Data System (ADS)

    Shaharun, Maizatul S.; Shaharun, Salina; Zabidi, Noor A. M.; Taha, Mohd F.

    2012-09-01

    Catalytic hydrogenation of CO2 to liquid fuel using copper based catalyst is an attractive way to recycle and utilize CO2. Zirconia-promoted copper-zinc oxide/alumina catalysts (CZAZ) were prepared by the co-precipitation method. The catalyst was characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive analysis (FESEM-EDX) and N2 adsorption-desorption. The results showed that addition of ZrO2 reduced the surface area and porosity of the catalyst. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. However the addition of zirconia led to a better dispersion of the active metal on the surface of support material.

  15. Corrosion behavior of zirconia in acidulated phosphate fluoride

    PubMed Central

    Thomas, Anie; Sridhar, Sathyanarayanan; Aghyarian, Shant; Watkins-curry, Pilanda; Chan, Julia Y.; Pozzi, Alessandro; Rodrigues, Danieli C.

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study. PMID:27008257

  16. Peri-implant bone response to retrieved human zirconia oral implants after a 4-year loading period: A histologic and histomorphometric evaluation of 22 cases.

    PubMed

    Kohal, Ralf-Joachim; Schwindling, Franz Sebastian; Bächle, Maria; Spies, Benedikt Christopher

    2016-11-01

    To evaluate the bone tissue response to surface modified zirconia oral implants retrieved from humans. Twenty-nine one-piece zirconia implants showed increased marginal bone loss and did not response to the applied peri-implantitis therapy. After their removal using a trephine bur, 22 of the implant-bone biopsies were suitable for an evaluation and immediately immersed in formalin for two weeks. Subsequent, the retrieved specimens were histologically prepared and the regions still showing osseointegration computer-assisted analyzed regarding the bone-to-implant contact (BIC) and bone density using a transmitted-light microscope. The removed implants were in situ for a mean time period of 47.7 months. After their removal, compact bone could be depicted at the apical regions. The remaining bone that was attached to the implants contained a regular lamellar structure with osteons and osteocytes. The BIC ranged from 58.1% to 93.7% (mean: 76.5%) and the bone area/density within the implant threads ranged from 57% to 97.2% (mean: 84.8%). The porous zirconia implants showed a sufficient BIC in the areas where bone still was attached. Although the implants had to be removed due to increased bone loss, it seems that the presented zirconia implant surface per se elicited appropriate osseointegration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1622-1631, 2016. © 2015 Wiley Periodicals, Inc.

  17. Microwave technique applied to the hydrothermal synthesis and sintering of calcia stabilized zirconia nanoparticles

    NASA Astrophysics Data System (ADS)

    Rizzuti, Antonino; Corradi, Anna; Leonelli, Cristina; Rosa, Roberto; Pielaszek, Roman; Lojkowski, Witold

    2010-01-01

    This study is focused on the synthesis of zirconia nanopowders stabilized by 6%mol calcia prepared under hydrothermal conditions using microwave technology. Sodium hydroxide-based hydrolysis of zirconyl chloride solution containing calcium nitrate followed by microwave irradiation at the temperature of 220 °C for 30 min was sufficient to obtain white powders of crystalline calcia stabilized zirconia. By means of X-ray diffraction and transmission electron microscopy, it was shown that tetragonal zirconia nanocrystallites with a size of ca 7 nm and diameter/standard deviation ratio of 0.10 were formed. The effects of the [Ca2+] and [NaOH] as well as temperature and time of microwave irradiation on the density and specific surface area were evaluated. Sintering test of the tetragonal nanopowders at 1,300 °C in air was performed in a monomode microwave applicator. The sample was sintered to the density of 95% and the grain size, analyzed by field emission scanning electron microscopy, was in the range from 90 to 170 nm.

  18. Synthesis of nanocrystalline zirconia by amorphous citrate route: structural and thermal (HTXRD) studies

    SciTech Connect

    Bhagwat, Mahesh; Ramaswamy, Veda

    2004-09-01

    Nanocrystalline zirconia powder with a fairly narrow particle size distribution has been synthesized by the amorphous citrate route. The sample obtained has a high BET surface area of 89 m{sup 2} g{sup -1}. Rietveld refinement of the powder X-ray diffraction (XRD) profile of the zirconia sample confirms stabilization of zirconia in the tetragonal phase with around 8% monoclinic impurity. The data show the presence of both anionic as well as cationic vacancies in the lattice. Crystallite size determined from XRD is 8 nm and is in close agreement with the particle size determined by TEM. The in situ high temperature-X-ray diffraction (HTXRD) study revealed high thermal stability of the mixture till around 1023 K after which the transformation of tetragonal phase into the monoclinic phase has been seen as a function of temperature till 1473 K. This transformation is accompanied by an increase in the crystallite size of the sample from 8 to 55 nm. The thermal expansion coefficients are 9.14 x 10{sup -6} K{sup -1} along 'a'- and 15.8 x 10{sup -6} K{sup -1} along 'c'-axis. The lattice thermal expansion coefficient in the temperature range 298-1623 K is 34.6 x 10{sup -6} K{sup -1}.

  19. Why Do We Need the Derivative for the Surface Area?

    ERIC Educational Resources Information Center

    Hristova, Yulia; Zeytuncu, Yunus E.

    2016-01-01

    Surface area and volume computations are the most common applications of integration in calculus books. When computing the surface area of a solid of revolution, students are usually told to use the frustum method instead of the disc method; however, a rigorous explanation is rarely provided. In this note, we provide one by using geometric…

  20. Why Do We Need the Derivative for the Surface Area?

    ERIC Educational Resources Information Center

    Hristova, Yulia; Zeytuncu, Yunus E.

    2016-01-01

    Surface area and volume computations are the most common applications of integration in calculus books. When computing the surface area of a solid of revolution, students are usually told to use the frustum method instead of the disc method; however, a rigorous explanation is rarely provided. In this note, we provide one by using geometric…

  1. Bone tissue response to experimental zirconia implants.

    PubMed

    Mihatovic, Ilja; Golubovic, Vladimir; Becker, Jürgen; Schwarz, Frank

    2017-03-01

    This study seeks to assess the bone tissue response at experimental zirconia implants in comparison with titanium implants by means of descriptive histology and histomorphometry in a dog model. Experimental zirconia implants with three different surface roughnesses (Z1 < Z2 < Z3) and conventional sandblasted large grit and acid-etched titanium implants were inserted bilaterally in the lower jaws of nine beagle dogs. Tissue biopsies were obtained after 3 and 14 days and 10 weeks of transmucosal healing. The tissue response was investigated by assessing new, old, and total bone-to-implant contact (nBIC, oBIC, and tBIC). After 3 days, histological specimens of all groups showed an intimate contact between the implant threads and pristine bone (tBIC: Ti 42.3 % > Z2 30.1 % > Z3 28.9 % > Z1 25.1 %, p > 0.05, unpaired t test, respectively). A provisional matrix was evident at all implant surfaces. At 14 days, percentages of BIC increased in all groups (tBIC: Ti 62.1 % > Z3 69.2 % < Z2 44.4 % > Z1 42.3 %; nBIC: Z3 58.9 % > Ti 52.2 % > Z2 35.1 % > Z1 32.5 %). Two implants, one of group Z1 and one of group Z2, were lost. At 10 weeks, 13 of 18 zirconia implants were lost, equally distributed between all three surface modifications. The remaining implants revealed increased BIC values (tBIC: Z3 69.5 % > Ti 58.5 % > Z1 49.7 % > Z2 37.1 %; nBIC: Z3 57.2 % > Ti 46.5 % > Z1 32.3 % > Z2 29.3 %). Histomorphometrical analysis showed comparable mean BIC values in all groups at all healing periods without showing statistical differences (p > 0.05, unpaired t test, respectively). The bone tissue response throughout the healing periods was characterized by a constant bone remodeling accompanied by resorption of old bone in favor of new bone formation at both titanium and zirconia implants. Surface roughness had a positive effect on BIC, although not showing statistical significance. Due to the poor survival rate, the

  2. Effect of sandblasting, silica coating, and laser treatment on the microtensile bond strength of a dental zirconia ceramic to resin cements.

    PubMed

    Mahmoodi, Nasrin; Hooshmand, Tabassom; Heidari, Solmaz; Khoshro, Kimia

    2016-02-01

    The purpose of this in vitro study was to evaluate the effect of laser irradiation as well as other surface treatment methods on the microtensile bond strength of a dental zirconia ceramic to the two types of resin cements. Zirconia ceramic blocks (ICE Zirkon) were sintered according to the manufacturer's instructions and duplicated in resin composites. The ceramic specimens were divided into four groups according to the following surface treatments: no surface treatment (control), sandblasting with alumina, silica coating plus silanization, and Nd:YAG laser irradiation. The specimens were divided equally and then bonded with Panavia F2.0 (self-etching resin cement) and Clearfil SA Luting (self-adhesive resin cement) to the composite blocks. The bonded ceramic-composite blocks were stored in distilled water at 37 °C for 72 h, cut to prepare bar-shaped specimens with a bonding area of approximately 1 mm(2), and thermocycled for 3000 cycles between 5 and 55 °C, and the microtensile bond strengths were measured using a universal testing machine. The data were analyzed by ANOVA and Tukey post hoc test. The results showed that the self-adhesive resin cement used in this study did not improve the microtensile bond strength when the zirconia surface was sandblasted by alumina. The use of the Nd:YAG laser did not enhance the bond strength between the zirconia and both types of resin cements. In addition, silica coating of the zirconia surfaces plus silane application significantly improved the bond strength regardless of the type of resin cement utilized.

  3. Osseointegration of zirconia implants: an SEM observation of the bone-implant interface

    PubMed Central

    Depprich, Rita; Zipprich, Holger; Ommerborn, Michelle; Mahn, Eduardo; Lammers, Lydia; Handschel, Jörg; Naujoks, Christian; Wiesmann, Hans-Peter; Kübler, Norbert R; Meyer, Ulrich

    2008-01-01

    Background The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. Methods A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. Results Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. Conclusion The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level. PMID:18990214

  4. Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

    DOE PAGES

    Li, Chen W.; Smith, Hillary L.; Lan, Tian; ...

    2015-04-13

    Inelastic neutron scattering measurements on monoclinic zirconia (ZrO2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhat moremore » anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.« less

  5. Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

    SciTech Connect

    Li, Chen W.; Smith, Hillary L.; Lan, Tian; Niedziela, Jennifer L.; Munoz, Jorge A.; Keith, J. Brian; Mauger, L.; Abernathy, Douglas L; Fultz, B.

    2015-04-13

    Inelastic neutron scattering measurements on monoclinic zirconia (ZrO2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhat more anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.

  6. Effect of polishing and glazing on the color and spectral distribution of monolithic zirconia

    PubMed Central

    Kim, Hee-Kyung; Kim, Sung-Hun; Han, Jung-Suk; Yeo, In-Sung

    2013-01-01

    PURPOSE The aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia. MATERIALS AND METHODS Forty-five monolithic zirconia specimens (16.3 mm × 16.4 mm × 2.0 mm) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (α=.05). RESULTS There was a significant difference in CIE L* between Subgroup N and P, and in CIE b* between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (ΔE*ab< 3.7) in most groups. Highly significant correlation was found between CIE b*and each subgroups as the number of coloring liquid applications increased (R2>0.88, P<.001). CONCLUSION A perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia. PMID:24049571

  7. Cytotoxicity and physicochemical characterization of iron–manganese-doped sulfated zirconia nanoparticles

    PubMed Central

    Al-Fahdawi, Mohamed Qasim; Rasedee, Abdullah; Al-Qubaisi, Mothanna Sadiq; Alhassan, Fatah H; Rosli, Rozita; El Zowalaty, Mohamed Ezzat; Naadja, Seïf-Eddine; Webster, Thomas J; Taufiq-Yap, Yun Hin

    2015-01-01

    Iron–manganese-doped sulfated zirconia nanoparticles with both Lewis and Brønsted acidic sites were prepared by a hydrothermal impregnation method followed by calcination at 650°C for 5 hours, and their cytotoxicity properties against cancer cell lines were determined. The characterization was carried out using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, Brauner–Emmett–Teller (BET) surface area measurements, X-ray fluorescence, X-ray photoelectron spectroscopy, zeta size potential, and transmission electron microscopy (TEM). The cytotoxicity of iron–manganese-doped sulfated zirconia nanoparticles was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays against three human cancer cell lines (breast cancer MDA-MB231 cells, colon carcinoma HT29 cells, and hepatocellular carcinoma HepG2 cells) and two normal human cell lines (normal hepatocyte Chang cells and normal human umbilical vein endothelial cells [HUVECs]). The results suggest for the first time that iron–manganese-doped sulfated zirconia nanoparticles are cytotoxic to MDA-MB231 and HepG2 cancer cells but have less toxicity to HT29 and normal cells at concentrations from 7.8 μg/mL to 500 μg/mL. The morphology of the treated cells was also studied, and the results supported those from the cytotoxicity study in that the nanoparticle-treated HepG2 and MDA-MB231 cells had more dramatic changes in cell morphology than the HT29 cells. In this manner, this study provides the first evidence that iron–manganese-doped sulfated zirconia nanoparticles should be further studied for a wide range of cancer applications without detrimental effects on healthy cell functions. PMID:26425082

  8. Simple Heat Treatment of Zirconia Ceramic Pre-Treated with Silane Primer to Improve Resin Bonding.

    PubMed

    Ha, Jung-Yun; Son, Jun Sik; Kim, Kyo-Han; Kwon, Tae-Yub

    2015-01-01

    Establishing a strong resin bond to dental zirconia ceramic remains difficult. Previous studies have shown that the conventional application of silane does not work well with zirconia. This paper reports that a silane pre-treatment of dental zirconia ceramic combined with subsequent heat treatment has potential as an adhesive cementation protocol for improving zirconia-resin bonding. Among the various concentrations (0.1 to 16 vol%) of experimental γ-methacryloxypropyltrimethoxysilane (γ-MPTS) primers assessed, the 1% solution was found to be the most effective in terms of the shear bond strength of the resin cement to dental zirconia ceramic. A high shear bond strength (approx. 30 MPa) was obtained when zirconia specimens were pre-treated with this primer and then heat-treated in a furnace for 60 min at 150 degrees C. Heat treatment appeared to remove the hydrophilic constituents from the silane film formed on the zirconia ceramic surface and accelerate the condensation reactions between the silanol groups of the hydrolyzed silane molecules at the zirconia/resin interface, finally making a more desirable surface for bonding with resin. This estimation was supported by Fourier transform infrared spectroscopy of the silanes prepared in this study.

  9. Dilemmas in zirconia bonding: A review.

    PubMed

    Dbradović-Djuricić, Kosovka; Medić, Vesna; Dodić, Slobodan; Gavrilov, Dragan; Antonijević, Djordje; Zrilić, Milorad

    2013-01-01

    This article presents a literature review on the resin bond to zirconia ceramic. Modern esthetic dentistry has highly recognized zirconia, among other ceramic materials. Biocompatibility of zirconia, chemical and dimensional stability, excellent mechanical properties, all together could guarantee optimal therapeutical results in complex prosthodontic reconstruction. On the other hand, low thermal degradation, aging of zirconia as well as problematic bonding of zirconia framework to dental luting cements and tooth structures, opened the room for discussion concerning their clinical durability.The well known methods of mechanical and chemical bonding used on glass-ceramics are not applicable for use with zirconia. Therefore, under critical clinical situations, selection of the bonding mechanism should be focused on two important points: high initial bond strength value and long term bond strength between zirconia-resin interface. Also, this paper emphases the use of phosphate monomer luting cements on freshly air-abraded zirconia as the simplest and most effective way for zirconia cementation procedure today.

  10. Measuring the surface area of aluminum hydroxide adjuvant.

    PubMed

    Johnston, Cliff T; Wang, Shan-Li; Hem, Stanley L

    2002-07-01

    The traditional method of determining surface area, nitrogen gas sorption, requires complete drying of the sample prior to analysis. This technique is not suitable for aluminum hydroxide adjuvant because it is composed of submicron, fibrous particles that agglomerate irreversibly upon complete removal of water. In this study, the surface area of a commercial aluminum hydroxide adjuvant was determined by a gravimetric/FTIR method that measures the water adsorption capacity. This technique does not require complete drying of the adjuvant. Five replicate determinations gave a mean surface area of 514 m(2)/g and a 95% confidence interval of 36 m(2)/g for a commercial aluminum hydroxide adjuvant. The X-ray diffraction pattern and the Scherrer equation were used to calculate the dimensions of the primary crystallites. The average calculated dimensions were 4.5 x 2.2 x 10 nm. Based on these dimensions, the mean calculated surface area of the commercial aluminum hydroxide adjuvant was 509 m(2)/g, and the 95% confidential interval was 30 m(2)/g. The close agreement between the two surface area values indicates that either method may be used to determine the surface area of aluminum hydroxide adjuvant. The high surface area, which was determined by two methods, is an important property of aluminum hydroxide adjuvants, and is the basis for the intrinsically high protein adsorption capacity. Copyright 2002 Wiley-Liss Inc.

  11. Ultrasonic cleaning of silica-coated zirconia influences bond strength between zirconia and resin luting material.

    PubMed

    Nishigawa, Goro; Maruo, Yukinori; Irie, Masao; Oka, Morihiko; Yoshihara, Kumiko; Minagi, Shogo; Nagaoka, Noriyuki; Yoshida, Yasuhiro; Suzuki, Kazuomi

    2008-11-01

    The purpose of this study was to evaluate how ultrasonic cleaning of silica-coated zirconia surfaces would influence the latter's bond strength to resin luting material. Forty zirconia specimens were divided into four groups: one air abrasion group and three silica-coated groups. Silica-coated specimens were cleaned with distilled water using an ultrasonic cleaner after tribochemical silica coating and then divided into three groups according to cleaning durations: 1 minute, 5 minutes, or without cleaning. Following which, resin luting material was polymerized against the specimens. After storage in water for 24 hours, the specimens were subjected to shear bond strength test. Shear bond strength of silica-coated group without cleaning was significantly higher than the other three groups, but there were no statistically significant differences among the three latter groups. SEM images suggested visible differences among the treatment methods. With EDXS analysis, it was revealed that ultrasonic cleaning decreased the silica content on the treated surfaces. Therefore, results showed that ultrasonic cleaning of tribochemically silica-coated zirconia surfaces decreased the adhesion efficacy to resin luting material.

  12. Attention to surfaces modulates motion processing in extrastriate area MT.

    PubMed

    Wannig, Aurel; Rodríguez, Valia; Freiwald, Winrich A

    2007-05-24

    In the visual system, early atomized representations are grouped into higher-level entities through processes of perceptual organization. Here we present neurophysiological evidence that a representation of a simple object, a surface defined by color and motion, can be the unit of attentional selection at an early stage of visual processing. Monkeys were cued by the color of a fixation spot to attend to one of two transparent random-dot surfaces, one red and one green, which occupied the same region of space. Motion of the attended surface drove neurons in the middle temporal (MT) visual area more strongly than physically identical motion of the non-attended surface, even though both occurred within the spotlight of attention. Surface-based effects of attention persisted even without differential surface coloring, but attentional modulation was stronger with color. These results show that attention can select surface representations to modulate visual processing as early as cortical area MT.

  13. Contamination of dental zirconia before final firing: effects on mechanical properties.

    PubMed

    Ban, Seiji; Okuda, Yuji; Noda, Makoto; Tsuruki, Jiro; Kawai, Tatsushi; Kono, Hiroshi

    2013-01-01

    Plate-like specimens were prepared, using a diamond saw, from Cercon -a pre-sintered yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) block. These specimens were treated with 10 kinds of dental materials which acted as contaminants, and then sintered at 1,350°C or 1,450°C. After the final firing, specimens were subjected to a three-point flexural test and Vickers hardness test. Their surfaces were also characterized by scanning electron microscopy and X-ray diffractometry. Phosphorus-containing contaminants reduced the three-point flexural strength and hardness of final sintered zirconia due to the formation of YPO4 and phase transformation from tetragonal to monoclinic zirconia. Gypsum also reduced both mechanical properties due to the formation of CaZrO3 and phase transformation from tetragonal to cubic zirconia. Other contaminants showed no adverse effects on the mechanical properties of final sintered zirconia.

  14. High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels.

    PubMed

    Muhoza, Sixbert P; Cottam, Matthew A; Gross, Michael D

    2017-04-16

    We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m(2)·g(-1). An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

  15. Phase transformation of a zirconia ceramic head after total hip arthroplasty.

    PubMed

    Haraguchi, K; Sugano, N; Nishii, T; Miki, H; Oka, K; Yoshikawa, H

    2001-09-01

    We report two cases of surface deterioration of a zirconia ceramic femoral head associated with phase transformation after total hip arthroplasty. One head was retrieved at revision due to recurrent dislocation after six years and the other because of failure of the locking mechanism of the polyethylene liner after three years. The monoclinic content of the zirconia ceramics rose from 1% to about 30% on the surface of the heads. SEM revealed numerous craters indicating extraction of the zirconia ceramics at the surface. Surface roughness increased from an initial value of 0.006 microm up to 0.12 microm. This is the first report to show that phase transformation of zirconia ceramics causes deterioration of the surface roughness of the head in vivo after total hip arthroplasty.

  16. MOISTURE AND SURFACE AREA MEASUREMENTS OF PLUTONIUM-BEARING OXIDES

    SciTech Connect

    Crowder, M.; Duffey, J.; Livingston, R.; Scogin, J.; Kessinger, G.; Almond, P.

    2009-09-28

    To ensure safe storage, plutonium-bearing oxides are stabilized at 950 C for at least two hours in an oxidizing atmosphere. Stabilization conditions are expected to decompose organic impurities, convert metals to oxides, and result in moisture content below 0.5 wt%. During stabilization, the specific surface area is reduced, which minimizes readsorption of water onto the oxide surface. Plutonium oxides stabilized according to these criteria were sampled and analyzed to determine moisture content and surface area. In addition, samples were leached in water to identify water-soluble chloride impurity content. Results of these analyses for seven samples showed that the stabilization process produced low moisture materials (< 0.2 wt %) with low surface area ({le} 1 m{sup 2}/g). For relatively pure materials, the amount of water per unit surface area corresponded to 1.5 to 3.5 molecular layers of water. For materials with chloride content > 360 ppm, the calculated amount of water per unit surface area increased with chloride content, indicating hydration of hygroscopic salts present in the impure PuO{sub 2}-containing materials. The low moisture, low surface area materials in this study did not generate detectable hydrogen during storage of four or more years.

  17. Preparation of Zirconia Supported Basic Nanocatalyst: A Physicochemical and Kinetic Study of Biodiesel Production from Soybean Oil.

    PubMed

    Patil, Pramod; Pratap, Amit

    2016-01-01

    Zirconia supported cadmium oxide basic nanocatalyst was prepared by simple co-precipitation method using aq. ammonia as precipitating reagent. The catalyst was characterised by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy technique (TEM), Brunauer-Emmet-Teller surface area measurement (BET), temperature program desorption (TPD-CO2) etc. The transesterificaton of soybean oil with methanol into biodiesel was catalysed by employing zirconia supported nanocatalyst. Kinetics of transesterificaton of oil was studied and obeyed the pseudo first order equation. While, the activation energy (Ea) for the transesterification of oil was found to be 41.18 kJ mol(-1). The 97% yield of biodiesel was observed using 7% catalyst loading (with respect of oil), 1:40 molar ratio of oil to methanol at 135°C.

  18. Sulfated zirconia as a proton conductor for fuel cells: Stability to hydrolysis and influence on catalysts

    NASA Astrophysics Data System (ADS)

    Tominaka, Satoshi; Momma, Toshiyuki; Scrosati, Bruno; Osaka, Tetsuya

    Sulfated zirconia is an inorganic solid superacid having sulfate groups covalently bonded to its surface. In this work, sulfated zirconia is synthesized by a solvent-free method to obtain it in the nanoparticle form. This nanostructured sulfated zirconia has been evaluated in terms of (i) chemical stability to hydrolysis and to hydrogen peroxide by thermogravimetric analysis, and (ii) influences on Pt catalyst activity by cyclic voltammetry using sulfated-zirconia dispersion as a supporting electrolyte solution. The results demonstrate that our sulfated zirconia is stable almost perfectly to hydrolysis but partly decomposed by a Fenton reagent containing hydrogen peroxide and Fe 2+. In addition, we show that oxygen reduction activity of Pt catalyst in a sulfated-zirconia dispersion is comparatively high (specific activity at 0.9 V vs. RHE, i 0.9: ca. 17 μA cm -2) compared to that in a 0.5 M sulfuric acid solution (i 0.9: ca. 15 μA cm -2). Finally, we demonstrate that sulfated zirconia does not influence hydrogen oxidation reaction. These results lead us to conclude that sulfated zirconia is a promising proton conductor for fuel cells.

  19. Determination of Reactive Surface Area of Melt Glass

    SciTech Connect

    Bourcier,W.L.; Roberts, S.; Smith, D.K.; Hulsey, S.; Newton,L.; Sawvel, A.; Bruton, C.; Papelis, C.; Um, W.; Russell, C. E.; Chapman,J.

    2000-10-01

    A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these samples. Based on measurements of analog and actual samples, it is recommended that the hydraulic source term calculations employ a range of 0.001 to 0.01 m{sup 2}/g for the reactive surface area of nuclear melt glass.

  20. Unique developmental trajectories of cortical thickness and surface area.

    PubMed

    Wierenga, Lara M; Langen, Marieke; Oranje, Bob; Durston, Sarah

    2014-02-15

    There is evidence that the timing of developmental changes in cortical volume and thickness varies across the brain, although the processes behind these differences are not well understood. In contrast to volume and thickness, the regional developmental trajectories of cortical surface area have not yet been described. The present study used a combined cross-sectional and longitudinal design with 201 MRI-scans (acquired at 1.5-T) from 135 typically developing children and adolescents. Scans were processed using FreeSurfer software and the Desikan-Killiany atlas. Developmental trajectories were estimated using mixed model regression analysis. Within most regions, cortical thickness showed linear decreases with age, whereas both cortical volume and surface area showed curvilinear trajectories. On average, maximum surface area occurred later in development than maximum volume. Global gender differences were more pronounced in cortical volume and surface area than in average thickness. Our findings suggest that developmental trajectories of surface area and thickness differ across the brain, both in their pattern and their timing, and that they also differ from the developmental trajectory of global cortical volume. Taken together, these findings indicate that the development of surface area and thickness is driven by different processes, at least in part.

  1. Wear performance of monolithic dental ceramics with different surface treatments.

    PubMed

    Preis, Verena; Weiser, Felix; Handel, Gerhard; Rosentritt, Martin

    2013-05-01

    To investigate the two-body wear performance of monolithic dental ceramics with different surface treatments. Standardized specimens (n = 8/ series) were fabricated from three monolithic dental ceramics (experimental translucent zirconia, experimental shaded zirconia, lithium disilicate). Four groups of each material were defined according to clinically relevant surface treatments: polished, polishedground, polished-ground-repolished, glazed. Two-body wear tests with steatite antagonists were performed in a chewing simulator. Surface roughness (R(a)) was controlled, and wear depths of specimens and antagonistic wear areas were calculated in relation to human enamel as reference. Statistical analysis of wear data was carried out using one-way ANOVA and Bonferroni multiple comparison test for post hoc analysis (α = .05). Scanning electron microscopy was applied for evaluating wear performance of ceramics and antagonists. Polished, ground, and repolished zirconia showed no wear, while glaze was abraded. Irrespective of the surface treatment, wear depth of lithium disilicate was significantly (P zirconia but only about half as high as for the enamel reference (274.14 µm). Mean relative wear areas of steatite antagonists (enamel reference: 1.25 mm2) ranged between 0.86 and 1.57 for zirconia, and between 1.79 and 2.28 for lithium disilicate, with the highest values found after grinding and glazing. Steatite surfaces were smooth when opposed to polished/ground/repolished zirconia, and ploughed when opposed to glaze and lithium disilicate. Translucent and shaded experimental zirconia yielded superior wear behavior and lower antagonistic wear compared to lithium disilicate. A trend to higher ceramic and antagonistic wear was shown after grinding and glazing.

  2. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns.

    PubMed

    Lameira, Deborah Pacheco; Buarque e Silva, Wilkens Aurélio; Andrade e Silva, Frederico; De Souza, Grace M

    2015-01-01

    The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37 °C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.

  3. Quantifying object and material surface areas in residences

    SciTech Connect

    Hodgson, Alfred T.; Ming, Katherine Y.; Singer, Brett C.

    2005-01-05

    The dynamic behavior of volatile organic compounds (VOCs) in indoor environments depends, in part, on sorptive interactions between VOCs in the gas phase and material surfaces. Since information on the types and quantities of interior material surfaces is not generally available, this pilot-scale study was conducted in occupied residences to develop and demonstrate a method for quantifying surface areas of objects and materials in rooms. Access to 33 rooms in nine residences consisting of bathrooms, bedroom/offices and common areas was solicited from among research group members living in the East San Francisco Bay Area. A systematic approach was implemented for measuring rooms and objects from 300 cm{sup 2} and larger. The ventilated air volumes of the rooms were estimated and surface area-to-volume ratios were calculated for objects and materials, each segregated into 20 or more categories. Total surface area-to-volume ratios also were determined for each room. The bathrooms had the highest total surface area-to-volume ratios. Bedrooms generally had higher ratios than common areas consisting of kitchens, living/dining rooms and transitional rooms. Total surface area-to-volume ratios for the 12 bedrooms ranged between 2.3 and 4.7 m{sup 2} m{sup -3}. The importance of individual objects and materials with respect to sorption will depend upon the sorption coefficients for the various VOC/materials combinations. When combined, the highly permeable material categories, which may contribute to significant interactions, had a median ratio of about 0.5 m{sup 2} m{sup -3} for all three types of rooms.

  4. Specific surface area as a maturity index of lunar fines

    NASA Technical Reports Server (NTRS)

    Gammage, R. B.; Holmes, H. F.

    1975-01-01

    Mature surface fines have an equilibrium specific surface area of about 0.6 sq m/g the equivalent mean particle size being about 3 microns. The adsorption behavior of inert gases (reversible isotherms) indicates that the particles are also nonporous in the size range of pores from 10 to 3000 A. Apparently, in mature soils there is a balance in the forces which cause fining, attrition, pore filling, and growth of lunar dust grains. Immature, lightly irradiated soils usually have coarser grains which reduce in size as aging proceeds. The specific surface area, determined by nitrogen or krypton sorption at 77 K, is a valuable index of soil maturity.

  5. Effect of various intraoral repair systems on the shear bond strength of composite resin to zirconia

    PubMed Central

    Han, In-Hae; Kang, Dong-Wan; Chung, Chae-Heon; Choe, Han-Cheol

    2013-01-01

    PURPOSE This study compared the effect of three intraoral repair systems on the bond strength between composite resin and zirconia core. MATERIALS AND METHODS Thirty zirconia specimens were divided into three groups according to the repair method: Group I- CoJet™ Repair System (3M ESPE) [chairside silica coating with 30 µm SiO2 + silanization + adhesive]; Group II- Ceramic Repair System (Ivoclar Vivadent) [etching with 37% phosphoric acid + Zirconia primer + adhesive]; Group III- Signum Zirconia Bond (Heraus) [Signum Zirconia Bond I + Signum Zirconia Bond II]. Composite resin was polymerized on each conditioned specimen. The shear bond strength was tested using a universal testing machine, and fracture sites were examined with FE-SEM. Surface morphology and wettability after surface treatments were examined additionally. The data of bond strengths were statistically analyzed with one-way ANOVA and Tamhane post hoc test (α=.05). RESULTS Increased surface roughness and the highest wettability value were observed in the CoJet sand treated specimens. The specimens treated with 37% phosphoric acid and Signum Zirconia Bond I did not show any improvement of surface irregularity, and the lowest wettability value were found in 37% phosphoric acid treated specimens. There was no significant difference in the bond strengths between Group I (7.80 ± 0.76 MPa) and III (8.98 ± 1.39 MPa). Group II (3.21 ± 0.78 MPa) showed a significant difference from other groups (P<.05). CONCLUSION The use of Intraoral silica coating system and the application of Signum Zirconia Bond are effective for increasing the bond strength of composite resin to zirconia. PMID:24049565

  6. The Zirconia Ceramic: Strengths and Weaknesses

    PubMed Central

    Daou, Elie E.

    2014-01-01

    Metal ceramic restorations were considered the gold standard as reliable materials. Increasing demand for esthetics supported the commercialization of new metal free restorations. A growing demand is rising for zirconia prostheses. Peer-reviewed articles published till July 2013 were identified through a Medline (Pubmed and Elsevier). Emphasizing was made on zirconia properties and applications. Zirconia materials are able to withstand posterior physiologic loads. Although zirconia cores are considered as reliable materials, these restorations are not problem free. PMID:24851138

  7. Measurements of BET Surface Area on Silica Nanosprings

    SciTech Connect

    Karkamkar, Abhijeet J.

    2008-09-01

    Nitrogen adsorption desorption isotherm for Silica nanosprings (GoNano2) samples deposited on substrate. The isotherm was obtained at 77 K using liquid N2 bath. The area of the substrate is 16 cm2. The amount of the sample is 0.44 mg/cm2. Amount of silica nanosprings= 7.04 mg. There is no indication of substantial micro or mesoporosity in the sample based on the nature of the isotherm. Eleven point BET surface area was measured. Nine points plotted. Goodness if fit R= 0.9992. BET surface area for silica nanosprings= 262 cm2/g

  8. Estimation of the specific surface area for a porous carrier.

    PubMed

    Levstek, Meta; Plazl, Igor; Rouse, Joseph D

    2010-03-01

    In biofilm systems, treatment performance is primarily dependent upon the available biofilm growth surface area in the reactor. Specific surface area is thus a parameter that allows for making comparisons between different carrier technologies used for wastewater treatment. In this study, we estimated the effective surface area for a spherical, porous polyvinyl alcohol (PVA) gel carrier (Kuraray) that has previously demonstrated effectiveness for retention of autotrophic and heterotrophic biomass. This was accomplished by applying the GPS-X modeling tool (Hydromantis) to a comparative analysis of two moving-bed biofilm reactor (MBBR) systems. One system consisted of a lab-scale reactor that was fed synthetic wastewater under autotrophic conditions where only the nitrification process was studied. The other was a pre-denitrification pilot-scale plant that was fed real, primary-settled wastewater. Calibration of an MBBR process model for both systems indicated an effective specific surface area for PVA gel of 2500 m2/m3, versus a specific surface area of 1000 m2/m3 when only the outer surface of the gel beads is considered. In addition, the maximum specific growth rates for autotrophs and heterotrophs were estimated to be 1.2/day and 6.0/day, respectively.

  9. Minimal adhesion surface area in tangentially loaded digital contacts.

    PubMed

    Terekhov, Alexander V; Hayward, Vincent

    2011-09-02

    The stick-to-slip transition of a fingertip in contact with a planar surface does not occur instantaneously. As the tangential load increases, portions of the skin adhere while others slip, giving rise to an evolution of the contact state, termed partial slip. We develop a quasi-static model that predicts that if the coefficient of kinetic friction is larger than the coefficient of static friction, then the stuck surface area diminishes as the tangential load increases until reaching a 'minimal adhesion surface area' where it vanishes abruptly. This phenomenon was observed in recently measured finger-slip image data (André et al., 2011) that were processed by an optic flow detection algorithm. We examined the results of 10 trials. Four of them exhibited the minimal adhesion surface area phenomenon, four of them did not, and two were inconclusive.

  10. Quantification of lung surface area using computed tomography.

    PubMed

    Yuan, Ren; Nagao, Taishi; Paré, Peter D; Hogg, James C; Sin, Don D; Elliott, Mark W; Loy, Leanna; Xing, Li; Kalloger, Steven E; English, John C; Mayo, John R; Coxson, Harvey O

    2010-10-31

    To refine the CT prediction of emphysema by comparing histology and CT for specific regions of lung. To incorporate both regional lung density measured by CT and cluster analysis of low attenuation areas for comparison with histological measurement of surface area per unit lung volume. The histological surface area per unit lung volume was estimated for 140 samples taken from resected lung specimens of fourteen subjects. The region of the lung sampled for histology was located on the pre-operative CT scan; the regional CT median lung density and emphysematous lesion size were calculated using the X-ray attenuation values and a low attenuation cluster analysis. Linear mixed models were used to examine the relationships between histological surface area per unit lung volume and CT measures. The median CT lung density, low attenuation cluster analysis, and the combination of both were important predictors of surface area per unit lung volume measured by histology (p < 0.0001). Akaike's information criterion showed the model incorporating both parameters provided the most accurate prediction of emphysema. Combining CT measures of lung density and emphysematous lesion size provides a more accurate estimate of lung surface area per unit lung volume than either measure alone.

  11. Evaluation of a conditioning method to improve core-veneer bond strength of zirconia restorations.

    PubMed

    Teng, Jili; Wang, Hang; Liao, Yunmao; Liang, Xing

    2012-06-01

    The high strength and fracture toughness of zirconia have supported its extensive application in esthetic dentistry. However, the fracturing of veneering porcelains remains one of the primary causes of failure. The purpose of this study was to evaluate, with shear bond strength testing, the effect of a simple and novel surface conditioning method on the core-veneer bond strength of a zirconia ceramic system. The shear bond strength of a zirconia core ceramic to the corresponding veneering porcelain was tested by the Schmitz-Schulmeyer method. Thirty zirconia core specimens (10 × 5 × 5 mm) were layered with a veneering porcelain (5 × 3 × 3 mm). Three different surface conditioning methods were evaluated: polishing with up to 1200 grit silicon carbide paper under water cooling, airborne-particle abrasion with 110 μm alumina particles, and modification with zirconia powder coating before sintering. A metal ceramic system was used as a control group. All specimens were subjected to shear force in a universal testing machine at a crosshead speed of 0.5 mm/min. The shear bond strength values were analyzed with 1-way ANOVA and Tukey's post hoc pairwise comparisons (α=.05). The fractured specimens were examined with a scanning electron microscope to observe the failure mode. The mean (SD) shear bond strength values in MPa were 47.02 (6.4) for modified zirconia, 36.66 (8.6) for polished zirconia, 39.14 (6.5) for airborne-particle-abraded zirconia, and 46.12 (7.1) for the control group. The mean bond strength of the control (P=.028) and modified zirconia groups (P=.014) was significantly higher than that of the polished zirconia group. The airborne-particle-abraded group was not significantly different from any other group. Scanning electron microscopy evaluation showed that cohesive fracture in the veneering porcelain was the predominant failure mode of modified zirconia, while the other groups principally fractured at the interface. Modifying the zirconia surface

  12. Residual stress of free-standing membranes of yttria-stabilized zirconia for micro solid oxide fuel cell applications.

    PubMed

    Tarancón, Albert; Sabaté, Neus; Cavallaro, Andrea; Gràcia, Isabel; Roqueta, Jaume; Garbayo, Iñigo; Esquivel, Juan P; Garcia, Gemma; Cané, Carles; Santiso, José

    2010-02-01

    The present study is devoted to analyze the compatibility of yttria-stabilized zirconia thin films prepared by pulsed laser deposition and metalorganic chemical vapor deposition techniques, with microfabrication processes based on silicon technologies for micro solid oxide fuel cells applications. Deposition of yttria-stabilized zirconia on Si/SiO2/Si3N4 substrates was optimized for both techniques in order to obtain high density and homogeneity, as well as a good crystallinity for film thicknesses ranging from 60 to 240 nm. In addition, stabilized zirconia free-standing membranes were fabricated from the deposited films with surface areas between 50 x 50 microm2 and 820 x 820 microm2. Particular emphasis was made on the analysis of the effect of the nature of the deposition technique and the different design and fabrication parameters (membrane area, thickness and substrate deposition temperature) on the residual stress of the membranes in order to control their thermomechanical stability for application as electrolyte in micro solid oxide fuel cells.

  13. Morphological and textural characterization of vanadium oxide supported on zirconia by ionic exchange

    NASA Astrophysics Data System (ADS)

    Gazzoli, Delia; De Rossi, Sergio; Ferraris, Giovanni; Valigi, Mario; Ferrari, Luisa; Selci, Stefano

    2008-12-01

    Zirconia-supported vanadium oxide samples containing vanadium up to 6.8 wt.% were prepared by ionic exchange using aqueous solution of peroxovanadate complexes and hydrous zirconium oxide. The samples, heated at 823 K for 5 h in air, were studied by several techniques, including X-ray diffraction, surface area determinations, diffuse reflectance spectroscopy (UV-vis), Raman spectroscopy, pore size distribution measurements and atomic force microscopy. The results showed that the preparation procedure applied leads to good vanadium dispersion. The interaction between the anchored surface species and the support affects some ZrO 2 properties, including texture and phase transition. Depending on the vanadium loading, several species formed. In the most diluted sample small polyvanadate entities predominate, whereas at increasing vanadium loading (up to about 6 V atoms nm -2) more condensed species formed yielding granular-type surface aggregates. At higher loading, granular-type particles and large flat structures, due to amorphous two- or three-dimensional polyvanadate species and ZrV 2O 7-like structures developed. Treatments with an ammonia solution specified that only a fraction of the vanadium species (in a polymeric form) interacts with the zirconia surface. Atomic force microscopy directly imaged the formation of vanadium aggregates (superimposed to the interacting species) at increasing vanadium content and their removal by the ammonia leaching.

  14. From Zirconium Nanograins to Zirconia Nanoneedles

    PubMed Central

    Zalnezhad, E.; Hamouda, A. M. S.; Jaworski, J.; Do Kim, Young

    2016-01-01

    Combinations of three simple techniques were utilized to gradually form zirconia nanoneedles from zirconium nanograins. First, a physical vapor deposition magnetron sputtering technique was used to deposit pure zirconium nanograins on top of a substrate. Second, an anodic oxidation was applied to fabricate zirconia nanotubular arrays. Finally, heat treatment was used at different annealing temperatures in order to change the structure and morphology from nanotubes to nanowires and subsequently to nanoneedles in the presence of argon gas. The size of the pure zirconium nanograins was estimated to be approximately 200–300 nm. ZrO2 nanotubular arrays with diameters of 70–120 nm were obtained. Both tetragonal and monoclinic ZrO2 were observed after annealing at 450 °C and 650 °C. Only a few tetragonal peaks appeared at 850 °C, while monoclinic ZrO2 was obtained at 900 °C and 950 °C. In assessing the biocompatibility of the ZrO2 surface, the human cell line MDA-MB-231 was found to attach and proliferate well on surfaces annealed at 850 °C and 450 °C; however, the amorphous ZrO2 surface, which was not heat treated, did not permit extensive cell growth, presumably due to remaining fluoride. PMID:27623486

  15. Shear bond strength of veneering porcelain to porous zirconia.

    PubMed

    Nakamura, Takashi; Sugano, Tsuyoshi; Usami, Hirofumi; Wakabayashi, Kazumichi; Ohnishi, Hiroshi; Sekino, Tohru; Yatani, Hirofumi

    2014-01-01

    In this study, two types of porous zirconia and dense zirconia were used. The flexural strength of non-layered zirconia specimens and those of the layered zirconia specimens with veneering porcelain were examined. Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia. The flexural strength of the layered specimens was 360 MPa for dense zirconia and 132 to 156 MPa for porous zirconia, when a load was applied to the porcelain side. The shear bond strength of porcelain veneered to dense zirconia was 27.4 MPa and that of porcelain veneered to porous zirconia was 33.6 to 35.1 MPa. This suggests that the veneering porcelain bonded strongly to porous zirconia although porous zirconia has a lower flexural strength than dense zirconia.

  16. Can foot anthropometric measurements predict dynamic plantar surface contact area?

    PubMed

    McPoil, Thomas G; Vicenzino, Bill; Cornwall, Mark W; Collins, Natalie

    2009-10-28

    Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 +/- 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001). The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

  17. A framework for predicting surface areas in microporous coordination polymers.

    PubMed

    Schnobrich, Jennifer K; Koh, Kyoungmoo; Sura, Kush N; Matzger, Adam J

    2010-04-20

    A predictive tool termed the linker to metal cluster (LiMe) ratio is introduced as a method for understanding surface area in microporous coordination polymers (MCPs). Calibrated with geometric accessible surface area computations, the LiMe ratio uses molecular weight of building block components to indicate the maximum attainable surface area for a given linker and metal cluster combination. MOF-5 and HKUST-1 are used as prototypical structures to analyze MCPs with octahedral M(4)O(CO(2)R)(6) and paddlewheel M(2)(CO(2)R)(4) metal clusters. Insight into the effects of linker size, geometry, number of coordinating groups, and framework interpenetration is revealed through the LiMe ratio analysis of various MCPs. Experimental surface area deviation provides indication that a material may suffer from incomplete guest removal, structural collapse, or interpenetration. Because minimal data input are required, the LiMe ratio surface area analysis is suggested as a quick method for experimental verification as well as a guide for the design of new materials.

  18. 3D-characterization of the veneer-zirconia interface using FIB nano-tomography.

    PubMed

    Mainjot, Amélie K; Douillard, Thierry; Gremillard, Laurent; Sadoun, Michaël J; Chevalier, Jérôme

    2013-02-01

    The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a challenge. However this interface has been reported to act on residual stress in the veneering ceramic, which plays a significant role in clinical failures such as chipping. The objective of this study was thus to investigate the veneer-zirconia interface using a recent 3D-analysis tool and to confront these observations to residual stress measurements in the veneering ceramic. Two cross-sectioned bilayered disc samples (veneer on zirconia), exhibiting different residual stress profiles in the veneering ceramic, were investigated using 2D and 3D imaging (respectively Scanning Electron Microscopy (SEM) and Focused Ion Beam nanotomography (FIB-nt), associated with chemical analysis by Energy Dispersive X-ray Spectroscopy (EDS). The observations did not reveal any structural change in the bulk of zirconia layer of both samples. However the presence of structural alterations and sub-surface microcracks were highlighted in the first micrometer of zirconia surface, exclusively for the sample exhibiting interior tensile stress in the veneering ceramic. No interdiffusion phenomena were observed. FIB nanotomography was proven to be a powerful technique to study the veneer-zirconia interface. The determination of the origin and the nature of zirconia alterations need to be further studied. The results of the present study support the hypothesis that zirconia surface property changes could be involved in the development of tensile stress in the veneering ceramic, increasing the risk of chipping. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now?

    PubMed

    Thompson, Jeffrey Y; Stoner, Brian R; Piascik, Jeffrey R; Smith, Robert

    2011-01-01

    Non-silicate ceramics, especially zirconia, have become a topic of great interest in the field of prosthetic and implant dentistry. A clinical problem with use of zirconia-based components is the difficulty in achieving suitable adhesion with intended synthetic substrates or natural tissues. Traditional adhesive techniques used with silica-based ceramics do not work effectively with zirconia. Currently, several technologies are being utilized clinically to address this problem, and other approaches are under investigation. Most focus on surface modification of the inert surfaces of high strength ceramics. The ability to chemically functionalize the surface of zirconia appears to be critical in achieving adhesive bonding. This review will focus on currently available approaches as well as new advanced technologies to address this problem. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Synthesis and Corrosion Study of Zirconia-Coated Carbonyl Iron Particles

    SciTech Connect

    Shen, R.; Shafrir, S.N.; Miao, C.; Wang, M.; Lambropoulos, J.C.; Jacobs, S.D.; Yang, H.

    2010-01-07

    This paper describes the surface modification of micrometer-sized magnetic carbonyl iron particles (CI) with zirconia from zirconium(IV) butoxide using a sol–gel method. Zirconia shells with various thicknesses and different grain sizes and shapes are coated on the surface of CI particles by changing the reaction conditions, such as the amounts of zirconia sol, nitric acid, and CI particles. A silica adhesive layer made from 3-aminopropyl trimethoxysilane (APTMS) can be introduced first onto the surface of CI particles in order to adjust both the size and the shape of zirconia crystals, and thus the roughness of the coating. The microanalyses on these coated particles are studied by field-emission scanning electron microscopy (FE-SEM) and X-ray-diffraction (XRD). Accelerated acid corrosion and air oxidation tests indicate that the coating process dramatically improved oxidation and acid corrosion resistances, which are critical issues in various applications of CI magnetic particles.

  1. Adhesion/cementation to zirconia and other non-silicate ceramics: Where are we now?

    PubMed Central

    Thompson, Jeffrey Y; Stoner, Brian R.; Piascik, Jeffrey R.; Smith, Robert

    2010-01-01

    Non-silicate ceramics, especially zirconia, have become a topic of great interest in the field of prosthetic and implant dentistry. A clinical problem with use of zirconia-based components is the difficulty in achieving suitable adhesion with intended synthetic substrates or natural tissues. Traditional adhesive techniques used with silica-based ceramics do not work effectively with zirconia. Currently, several technologies are being utilized clinically to address this problem, and other approaches are under investigation. Most focus on surface modification of the inert surfaces of high strength ceramics. The ability to chemically functionalize the surface of zirconia appears to be critical in achieving adhesive bonding. This review will focus on currently available approaches as well as new advanced technologies to address this problem. PMID:21094526

  2. On the interfacial fracture of porcelain/zirconia and graded zirconia dental structures

    PubMed Central

    Chai, Herzl; Lee, James J.-W; Mieleszko, Adam J.; Chu, Stephen J.; Zhang, Yu

    2014-01-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bend fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a FEA taking into account stress shielding effects due to the presence of adjacent channel cracks. The resulting GC was well less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred by a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good esthetic quality, graded Y-TZP emerges as a viable material concept for dental restorations. PMID:24769152

  3. On the interfacial fracture of porcelain/zirconia and graded zirconia dental structures.

    PubMed

    Chai, Herzl; Lee, James J-W; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

    2014-08-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good esthetic quality, graded Y-TZP emerges as a viable material concept for dental restorations.

  4. Observed Asteroid Surface Area in the Thermal Infrared

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Masiero, J.; Wright, E. L.; Bauer, J.; Grav, T.; Kramer, E.; Sonnett, S.

    2017-02-01

    The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emitted flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.

  5. High surface area electrode for high efficient microbial electrosynthesis

    NASA Astrophysics Data System (ADS)

    Nie, Huarong; Cui, Mengmeng; Lu, Haiyun; Zhang, Tian; Russell, Thomas; Lovley, Derek

    2012-02-01

    Microbial electrosynthesis, a process in which microorganisms directly accept electrons from an electrode to convert carbon dioxide and water into multi carbon organic compounds, affords a novel route for the generation of valuable products from electricity or even wastewater. The surface area of the electrode is critical for high production. A biocompatible, highly conductive, three-dimensional cathode was fabricated from a carbon nanotube textile composite to support the microorganism to produce acetate from carbon dioxide. The high surface area and macroscale porous structure of the intertwined CNT coated textile ?bers provides easy microbe access. The production of acetate using this cathode is 5 fold larger than that using a planar graphite electrode with the same volume. Nickel-nanowire-modified carbon electrodes, fabricated by microwave welding, increased the surface area greatly, were able to absorb more bacteria and showed a 1.5 fold increase in performance

  6. The "nylon T" intrauterine device: surface area versus copper adjunct.

    PubMed

    Kamal, I; Shaaban, H; Ezzat, R; Zaki, S

    1981-04-01

    A study to evaluate the relative effect of copper ions and increased surface area added through the wiring of the stem of the inert "T" device was performed. The experimental design was set up to test a hypothesis that the effectiveness of a copper device is a result of the increase in surface area of the IUD and not a result of the copper itself. Ninety-eight TCu 200 mm2 devices were stripped of their copper wire and rewound with a "nylon" thread of the same length, caliber and surface area. the devices were then repacked and gas sterilized. The 98 "nylon T" devices were fitted early in 1977 and followed up for 2 years. The major finding was that the replacement of copper wire on the "copper T" device by a "nylon" thread, "nylon T", had shown a comparable antifertility effect.

  7. Preparation and Evaluation of Carbon Coated Alumina as a High Surface Area Packing Material for High Performance Liquid Chromatography

    PubMed Central

    Paek, Changyub; McCormick, Alon V.; Carr, Peter W.

    2010-01-01

    The retention of polar compounds, the separation of structural isomers and thermal stability make carbonaceous materials very attractive stationary phases for Liquid Chromatography (LC). Carbon clad zirconia (C/ZrO2), one of the most interesting, exhibits unparalleled chemical and thermal stability, but its characteristically low surface area (20 – 30 m2/g) limits broader application as a second dimension separation in two-dimensional liquid chromatography (2DLC) where high retentivity and therefore high stationary phase surface area are required. In this work, we used a high surface area commercial HPLC alumina (153 m2/g) as a support material to develop a carbon phase by chemical vapor deposition (CVD) at elevated temperature using hexane vapor as the carbon source. The loading of carbon was varied by changing the CVD time and temperature, and the carbon coated alumina (C/Al2O3) was characterized both physically and chromatographically. The resulting carbon phases behaved as a reversed phase similar to C/ZrO2. At all carbon loadings, C/Al2O3 closely matched the unique chromatographic selectivity of carbon phases, and as expected the retentivity was increased over C/ZrO2. Excess carbon – the amount equivalent to 5 monolayers - was required to fully cover the oxide support in C/Al2O3, but this was less excess than needed with C/ZrO2. Plate counts were 60,000 – 76,000/meter for 5 μm particles. Spectroscopic studies (XPS and FT-IR) were also conducted; they showed that the two materials were chemically very similar. PMID:20850126

  8. Evolution of the surface area of a snow layer

    SciTech Connect

    Hanot, L.; Domine, F.

    1999-12-01

    Atmospheric trace gases can partition between the atmosphere and the snow surface. Because snow has a large surface-to-volume ratio, an important interaction potential between ice and atmospheric trace gases exists. Quantifying this partitioning requires the knowledge of the surface area (SA) of snow. Eleven samples were taken from a 50 cm thick snow fall at Col de Porte, near Grenoble (French Alps) between January 20 and February 4, 1998. Fresh snow and 3, 8, and 15-day-old snow were sampled at three different depths. Surface hoar, formed after the fall, was also sampled. Air and surface snow temperature, snow density, and snow fall rate were measured. Snow temperature always remained below freezing. Snow SA was measured using methane adsorption at 77.15 K. Values ranged from 2.25 m{sup 2}/g for fresh snow to 0.25 m{sup 2}/g for surface hoar and surface snow after 15 days. These values are much too high to be explained by the macroscopic aspect of snow crystals, and microstructures such as small rime droplets must have been present. Large decrease in SA with time were observed. The first meter of snowpack had a total surface area of about 50,000 m{sup 2} per m{sup 2} of ground. Reduction in SA will lead to the emission of adsorbed species by the snowpack, with possible considerable increase in atmospheric concentrations.

  9. Electrochemical capacitors utilizing low surface area carbon fiber

    SciTech Connect

    Lipka, S.M.

    1997-12-01

    The performance of electrochemical capacitors containing different commercial carbon fibers is reviewed. High specific capacitances (ca. 300 F/g) are obtained with low surface area carbon fiber (<1 m2/g) using a proprietary activation process. Capacitance is primarily achieved through pseudocapacitance resulting from surface functional groups. The performance of these devices is dependent on the type of carbon fiber, its carbon content, aspect ratio and microstructure. These devices can achieve high cycle life (ca. 100k) without significant loss in capacitance.

  10. Surface albedo spectral properties of geologically interesting areas on Titan

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Hirtzig, M.; Coustenis, A.; Bratsolis, E.; Le Mouélic, S.; Rodriguez, S.; Stephan, K.; Drossart, P.; Sotin, C.; Jaumann, R.; Brown, R. H.; Kyriakopoulos, K.; Lopes, R. M. C.; Bampasidis, G.; Stamatelopoulou-Seymour, K.; Moussas, X.

    2014-08-01

    We investigate the nature and possible formation processes of three areas on Titan's surface which have been suggested as geologically interesting: Hotei Regio, Tui Regio, and Sotra Patera. We also reanalyze the spectral characteristics of the Huygens Landing Site. We apply a statistical Principal Component Analysis (PCA) and a radiative transfer (RT) method on the Visual and Infrared Mapping Spectrometer Datacubes in order to retrieve the surface albedo of distinct spectral units in the near infrared. We have been able to exploit only a subset of the currently available Hotei Regio data, which are, in general, not optimal in terms of geometry for an analysis with a plane-parallel RT code. Our inferred surface albedos present generally higher values from 1 to 2 µm and lower ones at 0.94 and in the 2.6-5 µm region. The Regions of Interest (RoIs) within Hotei Regio, Tui Regio, and Sotra Patera are always significantly brighter than the surrounding areas. The largest variations are found longward of 2 µm and mainly at 5 µm. This higher surface albedo with respect to the surrounding area and, in general, the fact that the spectral behavior is different for each of these areas, is probably indicative of diverse chemical compositions and origins. We compare the spectral albedos with some suggested surface candidates on Titan (such as H2O, CO2, and CH4 ices, as well as tholin) and discuss possible chemical composition variations as well as other interpretations.

  11. Effective surface areas of coals measured by dye adsorption

    SciTech Connect

    Spitzer, D.P.

    1988-01-01

    The primary interest has been to examine adsorption behavior especially at short contact times, ten minutes to an hour, to determine whether such measurements might give useful data on effective surface areas - i.e., the surface that would be accessible to reagents within times comparable to those typical of most coal processing. Accordingly, most of the emphasis is on the effect of time on adsorption, rather than on traditional adsorption isotherms. Although most literature on cationic dye adsorption (mostly on carbons) uses methylene blue, it happened that the authors originally used safranin O instead because this dye was reported to be useful in distinguishing oxidized coals from fresh coals. Many of their experiments were repeated using methylene blue (in water), with very similar results. It was noted early that swelling of coals in water was common, especially for more oxidized or lower rank coals, and adsorption experiments were also done in another solvent, namely methanol. This produced quite striking differences for some coals. Coal surfaces that are readily accessible to adsorption by safranin are found to correlate well with N/sub 2/ surface areas, with adsorption of 1.0 mg safranin per gram of coal corresponding to essentially a surface area of 1.0 m/sup 2//g. Highly oxidized coals were found to swell considerably in water, with correspondingly increased adsorption. Areas of such coals can be estimated by adsorption of safranin from methanol solutions.

  12. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  13. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  14. High surface area carbon and process for its production

    DOEpatents

    Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter; Rash, Tyler; Shah, Parag; Suppes, Galen

    2016-12-13

    Activated carbon materials and methods of producing and using activated carbon materials are provided. In particular, biomass-derived activated carbon materials and processes of producing the activated carbon materials with prespecified surface areas and pore size distributions are provided. Activated carbon materials with preselected high specific surface areas, porosities, sub-nm (<1 nm) pore volumes, and supra-nm (1-5 nm) pore volumes may be achieved by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process.

  15. Improved Resin–Zirconia Bonding by Room Temperature Hydrofluoric Acid Etching

    PubMed Central

    Lee, Mun-Hwan; Son, Jun Sik; Kim, Kyo-Han; Kwon, Tae-Yub

    2015-01-01

    This in vitro study was conducted to evaluate the shear bond strength of “non-self-adhesive” resin to dental zirconia etched with hydrofluoric acid (HF) at room temperature and to compare it to that of air-abraded zirconia. Sintered zirconia plates were air-abraded (control) or etched with 10%, 20%, or 30% HF for either 5 or 30 min. After cleaning, the surfaces were characterized using various analytical techniques. Three resin cylinders (Duo-Link) were bonded to each treated plate. All bonded specimens were stored in water at 37 °C for 24 h, and then half of them were additionally thermocycled 5000 times prior to the shear bond-strength tests (n = 12). The formation of micro- and nano-porosities on the etched surfaces increased with increasing concentration and application time of the HF solution. The surface wettability of zirconia also increased with increasing surface roughness. Higher concentrations and longer application times of the HF solution produced higher bond-strength values. Infiltration of the resin into the micro- and nano-porosities was observed by scanning electron microscopy. This in vitro study suggests that HF slowly etches zirconia ceramic surfaces at room temperature, thereby improving the resin–zirconia bond strength by the formation of retentive sites. PMID:28787975

  16. Axilla surface area for males and females: measured distribution.

    PubMed

    Cowan-Ellsberry, Christina; McNamee, Pauline M; Leazer, Tyra

    2008-10-01

    With the recent introduction of exposure-based Quantitative Risk Assessment (QRA) as an approach to the evaluation, of materials in finished consumer products that are potential dermal sensitizers, the need for robust exposure data was clearly identified. The objective of this current study is to provide a value for the axilla surface area (SA) that is statistically derived and can be used in dermal sensitization QRA for ingredients of personal care products meant for use on the axilla. The axilla surface area measured for 60 men and 60 women resulted in a median surface area for a single axilla of 64.5 cm(2) for females and 135.5 cm(2) for males. These participants were representative of the United States population in their range of heights and weights. Furthermore, combining these surface area data with measured use data from this and other studies has enabled calculations of consumer exposure to solid APDO products on a dose/unit area/day basis (9.1 mg/cm(2)/d).

  17. Determining Surface Roughness in Urban Areas Using Lidar Data

    NASA Technical Reports Server (NTRS)

    Holland, Donald

    2009-01-01

    An automated procedure has been developed to derive relevant factors, which can increase the ability to produce objective, repeatable methods for determining aerodynamic surface roughness. Aerodynamic surface roughness is used for many applications, like atmospheric dispersive models and wind-damage models. For this technique, existing lidar data was used that was originally collected for terrain analysis, and demonstrated that surface roughness values can be automatically derived, and then subsequently utilized in disaster-management and homeland security models. The developed lidar-processing algorithm effectively distinguishes buildings from trees and characterizes their size, density, orientation, and spacing (see figure); all of these variables are parameters that are required to calculate the estimated surface roughness for a specified area. By using this algorithm, aerodynamic surface roughness values in urban areas can then be extracted automatically. The user can also adjust the algorithm for local conditions and lidar characteristics, like summer/winter vegetation and dense/sparse lidar point spacing. Additionally, the user can also survey variations in surface roughness that occurs due to wind direction; for example, during a hurricane, when wind direction can change dramatically, this variable can be extremely significant. In its current state, the algorithm calculates an estimated surface roughness for a square kilometer area; techniques using the lidar data to calculate the surface roughness for a point, whereby only roughness elements that are upstream from the point of interest are used and the wind direction is a vital concern, are being investigated. This technological advancement will improve the reliability and accuracy of models that use and incorporate surface roughness.

  18. How to Bond Zirconia: The APC Concept.

    PubMed

    Blatz, Markus B; Alvarez, Marcela; Sawyer, Kimiyo; Brindis, Marco

    2016-10-01

    Zirconia has become one of the most popular materials in dentistry. New high-translucent zirconia ceramics have favorable optical properties and can be applied as monolithic full-contour restorations in various clinical indications for posterior and anterior teeth. However, having reliable cementation protocols is fundamental for clinical success of indirect ceramic dental restorations, including those made from zirconia materials. Resin bonding supports ceramic restorations and is necessary for onlays, laminate veneers, and resinbonded fixed dental prostheses. The APC zirconia-bonding concept is based on decades of research on how to achieve high and long-term durable bond strengths to high-strength ceramics. It includes three practical steps: (A) airparticle abrasion, (P) zirconia primer, and (C) adhesive composite resin. This article discusses the history and development of high-translucent zirconia and explains the necessity for proper cementation. The rationale and science behind a simplified zirconia-bonding concept is explained and illustrated with a clinical case presentation.

  19. The effect of melt infiltration of borosilicate glass on biaxial flexural strength of porcelain-veneered zirconia

    NASA Astrophysics Data System (ADS)

    Joo, Kyu Ji; Song, Kyung Woo; Jung, Jong Hyun; Ahn, Hyo Jin; Park, Il Song; Lee, Min Ho; Bae, Tae Sung

    2011-08-01

    To evaluate the effect of melt infiltration on the biaxial flexural strength of porcelain-bonded zirconia, borosilicate glasses were used in this study. Presintered yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) blocks were milled and used for disc specimens. Prior to veneering of porcelain, the infiltration of borosilicate glass on zirconia was performed at 1,100 °C for 1 h. After a biaxial flexural test with the crosshead speed of 0.1 mm/min, fractured surfaces and interfaces between zirconia and veneer porcelain were observed with a Scanning Electron Microscope (SEM). The fracture strength of sintered zirconia and veneer porcelain was significantly increased by the melt infiltration of borosilicate glass (P < 0.05). The melt infiltration process of borosilicate glass greatly improved the Weibull modulus of sintered zirconia. However, the Weibull modulus of porcelain increased slightly. The sintered zirconia group showed a smooth fracture surface containing many pores, but the glass-infiltrated zirconia group showed a rough fracture surface.

  20. Effect of Time and Temperature on Transformation Toughened Zirconias.

    DTIC Science & Technology

    1987-06-01

    TTZ) and tetragonal airconia polycrystal ( TZP ), as well as sirconla toughened alumina (ZTA), among others. Zirconia based materials are of interest due... zirconia case, two ftctors that affect the analysis are the difficulty in resolving the tetragonal (101) and cubic (111) peaks when copper radiation is...The materials were magnesia stabilized transforma- tion toughened zirconia , yttria stabilized tetragonal zirconia polycrystal, and zirconia toughened

  1. Is zirconia a viable alternative to titanium for oral implant? A critical review.

    PubMed

    Sivaraman, Karthik; Chopra, Aditi; Narayan, Aparna I; Balakrishnan, Dhanasekar

    2017-08-17

    Titanium based implant systems, though considered as the gold standard for rehabilitation of edentulous spaces, have been criticized for many inherent flaws. The onset of hypersensitivity reactions, biocompatibility issues, and an unaesthetic gray hue have raised demands for more aesthetic and tissue compatible material for implant fabrication. Zirconia is emerging as a promising alternative to conventional Titanium based implant systems for oral rehabilitation with superior biological, aesthetics, mechanical and optical properties. This review aims to critically analyze and review the credibility of Zirconia implants as an alternative to Titanium for prosthetic rehabilitation. The literature search for articles written in the English language in PubMed and Cochrane Library database from 1990 till December 2016. The following search terms were utilized for data search: "zirconia implants" NOT "abutment", "zirconia implants" AND "titanium implants" AND "osseointegration", "zirconia implants" AND compatibility. The number of potential relevant articles selected were 47. All the human in vivo clinical, in vitro, animals' studies were included and discussed under the following subheadings: Chemical composition, structure and phases; Physical and mechanical properties; Aesthetic and optical properties; Osseointegration and biocompatibility; Surface modifications; Peri-implant tissue compatibility, inflammation and soft tissue healing, and long-term prognosis. Zirconia implants are a promising alternative to titanium with a superior soft-tissue response, biocompatibility, and aesthetics with comparable osseointegration. However, further long-term longitudinal and comparative clinical trials are required to validate zirconia as a viable alternative to the titanium implant. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  2. Shear bond strength of veneering porcelain to zirconia after argon plasma treatment.

    PubMed

    Canullo, Luigi; Micarelli, Costanza; Bettazzoni, Laura; Magnelli, Angela; Baldissara, Paolo

    2014-01-01

    The aim of this study was to investigate if argon plasma cleaning increases the shear bond strength between zirconia and veneering ceramic surfaces. Ninety tablets of densely sintered yttriastabilized tetragonal zirconia polycrystal were divided into three groups according to cleaning treatment (steam cleaning or plasma of Argon for 375 or 750 seconds). Groups were divided into two subgroups according to the application of a ceramic liner (A = liner, B = no liner). Within subgroup A, argon plasma cleaning significantly decreased shear bond strength. In subgroup B, the plasma treatment increased the shear bond strength, but the differences were not statistically significant. Subgroup A demonstrated lower shear bond strength compared to subgroup B. Argon plasma cleaning was suggested to improve the bond between ceramic and zirconia surfaces; however, when plasma cleaning was followed by a glassy liner application, the veneering ceramic/zirconia bond was significantly reduced.

  3. Estimating 3-dimensional colony surface area of field corals

    EPA Science Inventory

    Colony surface area is a critical descriptor for biological and physical attributes of reef-building (scleractinian, stony) corals. The three-dimensional (3D) size and structure of corals are directly related to many ecosystem values and functions. Most methods to estimate colony...

  4. Estimating 3-dimensional colony surface area of field corals

    EPA Science Inventory

    Colony surface area is a critical descriptor for biological and physical attributes of reef-building (scleractinian, stony) corals. The three-dimensional (3D) size and structure of corals are directly related to many ecosystem values and functions. Most methods to estimate colony...

  5. Increasing biochar surface area: effects of various milling

    USDA-ARS?s Scientific Manuscript database

    Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

  6. Increasing biochar surface area: Optimization of ball milling parameters

    USDA-ARS?s Scientific Manuscript database

    Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

  7. Comparison of the osteogenic potential of titanium- and modified zirconia-based bioceramics.

    PubMed

    Cho, Young-Dan; Shin, Ji-Cheol; Kim, Hye-Lee; Gerelmaa, Myagmar; Yoon, Hyung-In; Ryoo, Hyun-Mo; Kim, Dae-Joon; Han, Jung-Suk

    2014-03-13

    Zirconia is now favored over titanium for use in dental implant materials because of its superior aesthetic qualities. However, zirconia is susceptible to degradation at lower temperatures. In order to address this issue, we have developed modified zirconia implants that contain tantalum oxide or niobium oxide. Cells attached as efficiently to the zirconia implants as to titanium-based materials, irrespective of surface roughness. Cell proliferation on the polished surface was higher than that on the rough surfaces, but the converse was true for the osteogenic response. Cells on yttrium (Y)/tantalum (Ta)- and yttrium (Y)/niobium (Nb)-stabilized tetragonal zirconia polycrystals (TZP) discs ((Y, Ta)-TZP and (Y, Nb)-TZP, respectively) had a similar proliferative potential as those grown on anodized titanium. The osteogenic potential of MC3T3-E1 pre-osteoblast cells on (Y, Ta)-TZP and (Y, Nb)-TZP was similar to that of cells grown on rough-surface titanium. These data demonstrate that improved zirconia implants, which are resistant to temperature-induced degradation, retain the desirable clinical properties of structural stability and support of an osteogenic response.

  8. Comparison of the Osteogenic Potential of Titanium and Modified Zirconia-Based Bioceramics

    PubMed Central

    Cho, Young-Dan; Shin, Ji-Cheol; Kim, Hye-Lee; Gerelmaa, Myagmar; Yoon, Hyung-In; Ryoo, Hyun-Mo; Kim, Dae-Joon; Han, Jung-Suk

    2014-01-01

    Zirconia is now favored over titanium for use in dental implant materials because of its superior aesthetic qualities. However, zirconia is susceptible to degradation at lower temperatures. In order to address this issue, we have developed modified zirconia implants that contain tantalum oxide or niobium oxide. Cells attached as efficiently to the zirconia implants as to titanium-based materials, irrespective of surface roughness. Cell proliferation on the polished surface was higher than that on the rough surfaces, but the converse was true for the osteogenic response. Cells on yttrium oxide (Y2O3)/tantalum oxide (Ta2O5)- and yttrium oxide (Y2O3)/niobium oxide (Nb2O5)-containing tetragonal zirconia polycrystals (TZP) discs ((Y, Ta)-TZP and (Y, Nb)-TZP, respectively) had a similar proliferative potential as those grown on anodized titanium. The osteogenic potential of MC3T3-E1 pre-osteoblast cells on (Y, Ta)-TZP and (Y, Nb)-TZP was similar to that of cells grown on rough-surface titanium. These data demonstrate that improved zirconia implants, which are resistant to temperature-induced degradation, retain the desirable clinical properties of structural stability and support of an osteogenic response. PMID:24633198

  9. Interface Surface Area Tracking for the Conservative Level Set Method

    NASA Astrophysics Data System (ADS)

    Firehammer, Stephanie; Desjardins, Olivier

    2015-11-01

    One key question in liquid-gas flows is how to model the interface between phases in a way that is mass, momentum, and energy conserving. The accurate conservative level set (ACLS) method of Desjardins et al. provides a tool for tracking a liquid-gas interface with minimal mass conservation issues; however, it does not explicitly compute the interface surface area and thus nothing can be said a priori about the balance between kinetic energy and surface energy. This work examines an equation for the transport of interface surface area density, which can be written in terms of the gradient of the volume fraction. Furthermore this presentation will outline a numerical method for jointly transporting a conservative level set and surface area density. Finally, we will explore oppportunities for energy conservation via the accurate exchange of energy between the flow field and the interface through surface tension, with test cases to show the results of our extended ACLS method. Funding from the National Science Foundation is gratefully acknowledged.

  10. Surface topography analysis with application of roughness area dependence method.

    PubMed

    Szyszka, Adam; Wośko, Mateusz; Szymański, Tomasz; Paszkiewicz, Regina

    2016-11-01

    At the moment the root mean square roughness (Rq) is the most commonly used parameter for quantitative description of surface properties. However, this parameter has one main disadvantage: for its calculation only height variations of surface profile are used which are then represented by a single number. To eliminate this restriction authors of the paper have developed a surface analysis method which is based on roughness calculation in the function of gradually increasing dimensions of a sampling area. By setting proper measurement parameters and further data processing, from Rq dependence on sampling area plot size there is a possibility to obtain more useful, additional information about specific surface properties than using the single roughness value. Roughness area dependence plots, obtained from AFM images, were analyzed to study the influence of different growth parameters on surface properties of GaN layers and AlGaN/GaN heterostructures grown on sapphire and silicon substrates by Metal Organic Chemical Vapor Deposition (MOVPE) epitaxy. Although the method was used to characterize the semiconductor material in micrometer range, it can be applied also for any topography imaging technique in wide scale ranges. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

    PubMed Central

    Oh, Gye-Jeong; Yun, Kwi-Dug; Lee, Kwang-Min; Lim, Hyun-Pil

    2010-01-01

    PURPOSE The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest® ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block. PMID:21165274

  12. Effect of milling temperatures on surface area, surface energy and cohesion of pharmaceutical powders.

    PubMed

    Shah, Umang V; Wang, Zihua; Olusanmi, Dolapo; Narang, Ajit S; Hussain, Munir A; Tobyn, Michael J; Heng, Jerry Y Y

    2015-11-10

    Particle bulk and surface properties are influenced by the powder processing routes. This study demonstrates the effect of milling temperatures on the particle surface properties, particularly surface energy and surface area, and ultimately on powder cohesion. An active pharmaceutical ingredient (API) of industrial relevance (brivanib alaninate, BA) was used to demonstrate the effect of two different, but most commonly used milling temperatures (cryogenic vs. ambient). The surface energy of powders milled at both cryogenic and room temperatures increased with increasing milling cycles. The increase in surface energy could be related to the generation of surface amorphous regions. Cohesion for both cryogenic and room temperature milled powders was measured and found to increase with increasing milling cycles. For cryogenic milling, BA had a surface area ∼ 5× higher than the one obtained at room temperature. This was due to the brittle nature of this compound at cryogenic temperature. By decoupling average contributions of surface area and surface energy on cohesion by salinization post-milling, the average contribution of surface energy on cohesion for powders milled at room temperature was 83% and 55% at cryogenic temperature. Copyright © 2015. Published by Elsevier B.V.

  13. Bonding of Resin Cement to Zirconia with High Pressure Primer Coating

    PubMed Central

    Wang, Ying-jie; Jiao, Kai; Liu, Yan; Zhou, Wei; Shen, Li-juan; Fang, Ming; Li, Meng; Zhang, Xiang; Tay, Franklin R.; Chen, Ji-hua

    2014-01-01

    Objectives To investigate the effect of air-drying pressure during ceramic primer coating on zirconia/resin bonding and the surface characteristics of the primed zirconia. Methods Two ceramic primers (Clearfil Ceramic Primer, CCP, Kuraray Medical Inc. and Z-Prime Plus, ZPP, Bisco Inc.) were applied on the surface of air-abraded zirconia (Katana zirconia, Noritake) and dried at 4 different air pressures (0.1–0.4 MPa). The primed zirconia ceramic specimens were bonded with a resin-based luting agent (SA Luting Cement, Kuraray). Micro-shear bond strengths of the bonded specimens were tested after 3 days of water storage or 5,000× thermocycling (n = 12). Failure modes of the fractured specimens were examined with scanning electron miscopy. The effects of air pressure on the thickness of the primer layers and the surface roughness (Sa) of primed zirconia were evaluated using spectroscopic ellipsometry (n = 6), optical profilometry and environmental scanning electron microscopy (ESEM) (n = 6), respectively. Results Clearfil Ceramic Primer air-dried at 0.3 and 0.4 MPa, yielding significantly higher µSBS than gentle air-drying subgroups (p<0.05). Compared to vigorous drying conditions, Z-Prime Plus air-dried at 0.2 MPa exhibited significantly higher µSBS (p<0.05). Increasing air-drying pressure reduced the film thickness for both primers. Profilometry measurements and ESEM showed rougher surfaces in the high pressure subgroups of CCP and intermediate pressure subgroup of ZPP. Conclusion Air-drying pressure influences resin/zirconia bond strength and durability significantly. Higher air-drying pressure (0.3-0.4 MPa) for CCP and intermediate pressure (0.2 MPa) for ZPP are recommended to produce strong, durable bonds between resin cement and zirconia ceramics. PMID:24992678

  14. Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

    PubMed

    Alsadon, Omar; Patrick, David; Johnson, Anthony; Pollington, Sarah; Wood, Duncan

    2017-02-11

    The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA. The zirconia/composite crowns subjected to static occlusal load showed comparable results to the zirconia/porcelain crowns. Zirconia/composite crowns showed higher stress on the zirconia substructure at 63.6 and 50.9 MPa on the zirconia substructure veneered with porcelain. In conclusion, zirconia/composite crowns withstood high occlusal loads similar to zirconia/porcelain crowns with no significant difference. However, the zirconia/composite crowns showed higher stress values than the zirconia/porcelain crowns at the zirconia substructure.

  15. [Study on friction and wear properties of dental zirconia ceramics processed by microwave and conventional sintering methods].

    PubMed

    Guoxin, Hu; Ying, Yang; Yuemei, Jiang; Wenjing, Xia

    2017-04-01

    This study evaluated the wear of an antagonist and friction and wear properties of dental zirconia ceramic that was subjected to microwave and conventional sintering methods. Ten specimens were fabricated from Lava brand zirconia and randomly assigned to microwave and conventional sintering groups. A profile tester for surface roughness was used to measure roughness of the specimens. Wear test was performed, and steatite ceramic was used as antagonist. Friction coefficient curves were recorded, and wear volume were calculated. Finally, optical microscope was used to observe the surface morphology of zirconia and steatite ceramics. Field emission scanning electron microscopy was used to observe the microstructure of zirconia. Wear volumes of microwave and conventionally sintered zirconia were (6.940±1.382)×10⁻², (7.952±1.815) ×10⁻² mm³, respectively. Moreover, wear volumes of antagonist after sintering by the considered methods were (14.189±4.745)×10⁻², (15.813±3.481)×10⁻² mm³, correspondingly. Statistically significant difference was not observed in the wear resistance of zirconia and wear volume of steatite ceramic upon exposure to two kinds of sintering methods. Optical microscopy showed that ploughed surfaces were apparent in zirconia. The wear surface of steatite ceramic against had craze, accompanied by plough. Scanning electron microscopy showed that zirconia was sintered compactly when subjected to both conventional sintering and microwave methods, whereas grains of zirconia sintered by microwave alone were smaller and more uniform. Two kinds of sintering methods are successfully used to produce dental zirconia ceramics with similar friction and wear properties.
.

  16. Excess surface area in bioelectrochemical systems causes ion transport limitations

    PubMed Central

    Harrington, Timothy D.; Babauta, Jerome T.; Davenport, Emily K.; Renslow, Ryan S.; Beyenal, Haluk

    2014-01-01

    We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: 1) showing that serially increasing NaCl concentration up to 200 mM increased current linearly up to a total of +273% vs. 0 mM NaCl under advective conditions, 2) growing the biofilm with a starting concentration of 200 mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and 3) showing that un-colonized surface area remained even after steady-state current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential at the electrode surface. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant. PMID:25421463

  17. Surface area and conductivity of polyaniline synthesized under UV irradiation

    NASA Astrophysics Data System (ADS)

    Budi, S.; Fitri, E.; Paristiowati, M.; Cahyana, U.; Pusparini, E.; Nasbey, H.; Imaddudin, A.

    2017-02-01

    This paper reports our study on the synthesis of high electrical conductivity and surface area polyaniline using oxidative polymerization under UV light irradiation. The formation of emeraldine structures of polyaniline was revealed by major absorption bands of FTIR (Fourier transform infrared spectroscopy) spectra attributed to C-N stretching, C=C stretching in the benzenoid ring, C=C stretching in the quinoid ring and QNH+B stretching. XRD (X-ray diffractometer) measurements confirmed typical diffraction patterns with a crystallinity of 13% and 16% for polyaniline prepared under non-stirred and stirred reaction, respectively. SEM (Scanning electron microscope) studies showed more uniform morphology of polyaniline was obtained with stirring reaction process compare to those prepared without stirring. Surface analysis using SAA (surface area analyzer) showed that pure polyaniline with the relatively high surface area of ca.28 m2/g was successfully prepared in this work. Based on four point probe measurement, the prepared polyaniline possesses high conductivity which is important in electrode application.

  18. Sol-gel synthesis and catalytic properties of sulfated zirconia catalysts

    SciTech Connect

    Li, B.; Gonzalez, R.D.

    1996-09-01

    Sulfated zirconia catalysts were prepared using a sol-gel method with zirconium n-propoxide as the alkoxide precursor and a water/alkoxide ratio of 40. The strength of the sulfuric acid solution used to activate the zirconia was found to be an important variable in the synthesis of the superacid catalyst. A maximum both in the BET surface area and in the activity observed in the isomerization of n-butane was observed when 0.5 N H{sub 2}SO{sub 4} was used. Rehydration in air following calcination at 600 C requires that excess moisture be removed prior to reaction. The deactivation rate of the sample could be reduced by introducing H{sub 2} into the feed. A TGA-mass spectroscopy study of the deactivated catalysts shows two SO{sub 2} desorption maxima at 600 and 900 C. The SO{sub 2} desorption maximum at 600 C is coincident with a CO{sub 2} maximum at the same temperature. These results are interpreted in terms of an organo-sulfur complex on the surface of the deactivated catalyst.

  19. A fast pairwise evaluation of molecular surface area.

    PubMed

    Vasilyev, Vladislav; Purisima, Enrico O

    2002-05-01

    A fast and general analytical approach was developed for the calculation of the approximate van der Waals and solvent-accessible surface areas. The method is based on three basic ideas: the use of the Lorentz transformation formula, a rigid-geometry approximation, and a single fitting parameter that can be refitted on the fly during a simulation. The Lorentz transformation equation is used for the summation of the areas of an atom buried by its neighboring contacting atoms, and implies that a sum of the buried pairwise areas cannot be larger than the surface area of the isolated spherical atom itself. In a rigid-geometry approximation we numerically calculate and keep constant the surface of each atom buried by the atoms involved in 1-2 and 1-3 interactions. Only the contributions from the nonbonded atoms (1-4 and higher interactions) are considered in terms of the pairwise approximation. The accuracy and speed of the method is competitive with other pairwise algorithms. A major strength of the method is the ease of parametrization.

  20. Is there a potential for durable adhesion to zirconia restorations? A systematic review.

    PubMed

    Tzanakakis, Emmanouil-George C; Tzoutzas, Ioannis G; Koidis, Petros T

    2016-01-01

    With a number of zirconia ceramic materials currently available for clinical use, an overview of the scientific literature on the adhesion methods and their potential influence is indicated. The purpose of this systematic review was to classify and analyze the existing methods and materials proposed to improve adhesion to zirconia surfaces. The current literature of in vitro studies examining the bond strength on zirconia ceramics, including clinical studies from 1998 until 2014, was analyzed. A search of the English language literature was undertaken using MEDLINE and PubMed, and a hand search was made for any relevant research paper from the library of a dental school. Papers evaluating only alumina restoration bond or ceramic-zirconia bond were excluded. A total of 134 publications were identified for analysis. Different adhesive techniques with different testing methods were reviewed. Results were difficult to compare in that the parameters varied in each research protocol. Airborne-particle abrasion and tribochemical silica coating are reference pretreatment methods. Adhesive monomers are necessary for chemical bonding. Surface contamination and aging have negative effects on adhesion to zirconia. Many factors influence each combination of zirconia material, such as surface treatment, adhesive medium, and aging conditions. Laboratory studies should be confirmed by clinical trials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Tropical cyclone rainfall area controlled by relative sea surface temperature

    PubMed Central

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-01-01

    Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates. PMID:25761457

  2. Sol-gel derived bioactive coating on zirconia: Effect on flexural strength and cell proliferation.

    PubMed

    Shahramian, Khalil; Leminen, Heidi; Meretoja, Ville; Linderbäck, Paula; Kangasniemi, Ilkka; Lassila, Lippo; Abdulmajeed, Aous; Närhi, Timo

    2016-09-07

    The purpose of this study was to evaluate the effect of sol-gel derived bioactive coatings on the biaxial flexural strength and fibroblast proliferation of zirconia, aimed to be used as an implant abutment material. Yttrium stabilized zirconia disc-shaped specimens were cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n = 15) were fabricated, zirconia with sol-gel derived titania (TiO2 ) coating, zirconia with sol-gel derived zirconia (ZrO2 ) coating, and non-coated zirconia as a control. The surfaces of the specimens were analyzed through images taken using a scanning electron microscope (SEM), and a non-contact tapping mode atomic force microscope (AFM) was used to record the surface topography and roughness of the coated specimens. Biaxial flexural strength values were determined using the piston-on-three ball technique. Human gingival fibroblast proliferation on the surface of the specimens was evaluated using AlamarBlue assay™. Data were analyzed using a one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Additionally, the biaxial flexural strength data was also statistically analyzed with the Weibull distribution. The biaxial flexural strength of zirconia specimens was unaffected (p > 0.05). Weibull modulus of TiO2 coated and ZrO2 coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO2 showed significantly lower fibroblast proliferation compared to other groups (p < 0.05). In conclusion, sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO2 coated specimens showed significantly lower cell proliferation after 12 days than TiO2 coated or non-coated control. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016. © 2016 Wiley Periodicals, Inc.

  3. Reliability and properties of ground Y-TZP-zirconia ceramics.

    PubMed

    Luthardt, R G; Holzhüter, M; Sandkuhl, O; Herold, V; Schnapp, J D; Kuhlisch, E; Walter, M

    2002-07-01

    Yttria-stabilized zirconia ceramics is a high-performance material with excellent biocompatibility and mechanical properties, which suggest its suitability for posterior fixed partial dentures. The hypothesis under examination is that the strength and reliability of Y-TZP zirconia ceramics are affected by the inner surface grinding of crowns, and vary with the grinding parameter. Flexural strength, surface roughness, and fracture toughness were determined on samples machined by face and peripheral grinding with varied feed velocities and cutting depths. Results have been compared with those on lapped samples. Analysis of variance and Weibull parameter were used for statistical analysis. It was found that inner surface grinding significantly reduces the strength and reliability of Y-TZP zirconia compared with the lapped control sample. Co-analysis of flexural strength, Weibull parameter, and fracture toughness showed counteracting effects of surface compressive stress and grinding-introduced surface flaws. In conclusion, grinding of Y-TZP needs to be optimized to achieve the CAD/CAM manufacture of all-ceramic restorations with improved strength and reliability.

  4. High Surface Area Nanoporous Polymers for Reversible HydrogenStorage

    SciTech Connect

    Germain, Jonathan; Hradil, Jiri; Frechet, Jean M.J.; Svec,Frantisek

    2006-06-29

    Hydrogen adsorption using a series of nanoporous synthetic polymers has been studied. Promising results were obtained during the screening of commercially available porous polymer beads; of the polymers considered, hypercrosslinked Hypersol-Macronet MN200 resin exhibited the highest adsorption capacity for hydrogen. This initial success triggered the development of our own high surface area hypercrosslinked materials. Subjecting gel-type and macroporous vinylbenzyl chloride-based precursors swollen in dichloroethane to a Friedel-Crafts reaction catalyzed by iron trichloride afforded beads with surface areas of 1 930 and 1 300 m{sup 2}/g, respectively, as calculated using the BET equation. The former polymer reversibly stores up to 1.5 wt % H{sub 2} at a pressure of 0.12 MPa and a temperature of 77.3 K. The initial heat of adsorption of hydrogen molecules onto this polymer is 6.6 kJ/mol.

  5. Tokamak dust particle size and surface area measurement

    SciTech Connect

    Carmack, W.J.; Smolik, G.R.; Anderl, R.A.; Pawelko, R.J.; Hembree, P.B.

    1998-07-01

    The INEEL has analyzed a variety of dust samples from experimental tokamaks: General Atomics` DII-D, Massachusetts Institute of Technology`s Alcator CMOD, and Princeton`s TFTR. These dust samples were collected and analyzed because of the importance of dust to safety. The dust may contain tritium, be activated, be chemically toxic, and chemically reactive. The INEEL has carried out numerous characterization procedures on the samples yielding information useful both to tokamak designers and to safety researchers. Two different methods were used for particle characterization: optical microscopy (count based) and laser based volumetric diffraction (mass based). Surface area of the dust samples was measured using Brunauer, Emmett, and Teller, BET, a gas adsorption technique. The purpose of this paper is to present the correlation between the particle size measurements and the surface area measurements for tokamak dust.

  6. High Surface Area Inorganic Membrane for Water Removal

    SciTech Connect

    2008-12-01

    This factsheet describes a research project whose objective is to demonstrate the fabrication and performance advantages of minichannel planar membrane modules made of porous metallic supports of surface area packing density one order of magnitude higher than the conventional membrane tube. The new, transformational, ceramic/metallic, hybrid membrane technology will be used for water/ethanol separations and reduce energy consumption by >20% over distillation and adsorption.

  7. Experimental and DFT studies of initiation processes for butane isomerization over sulfated-zirconia catalysts

    SciTech Connect

    Hong, Z.; Watwe, R.M.; Natal-Santiago, M.A.; Hill, J.M.; Dumesic, J.A.; Fogash, K.B.; Kim, B.; Masqueda-Jimenez, B.I.

    1998-09-10

    Reaction kinetics studies were conducted of isobutane and n-butane isomerization at 423 K over sulfated-zirconia, with the butane feeds purified of olefins. Dihydrogen evolution was observed during butane isomerization over fresh catalysts, as well as over catalysts selectively poisoned by preadsorbed ammonia. Butane isomerization over sulfated-zirconia can be viewed as a surface chain reaction comprised of initiation, propagation, and termination steps. The primary initiation step in the absence of feed olefins is considered to be the dehydrogenation of butane over sulfated-zirconia, generating butenes which adsorb onto acid sites to form protonated olefinic species associated with the conjugate base form of the acid sites. Quantum-chemical calculations, employing density-functional theory, suggest that the dissociative adsorption of dihydrogen, isobutylene hydrogenation, and dissociative adsorption of isobutane are feasible over the sulfated-zirconia cluster, and these reactions take place over Zr-O sites.

  8. Facile synthesis of high surface area molybdenum nitride and carbide

    SciTech Connect

    Roy, Aaron; Serov, Alexey; Artyushkova, Kateryna; Brosha, Eric L.; Atanassov, Plamen; Ward, Tim L.

    2015-08-15

    The synthesis of high surface area γ-Mo{sub 2}N and α-Mo{sub 2}C is reported (116 and 120 m{sup 2}/g) without the temperature programmed reduction of MoO{sub 3}. γ-Mo{sub 2}N was prepared in an NH{sub 3}-free synthesis using forming gas (7 at% H{sub 2}, N{sub 2}-balance) as the reactive atmosphere. Three precursors were studied ((NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O, (NH{sub 4}){sub 2} Mg(MoO{sub 4}){sub 2}, and MgMoO{sub 4}) along with the sacrificial support method (SSM) as a means of reducing the particle size of Mo{sub 2}N and Mo{sub 2}C. In situ X-ray diffraction (XRD) studies were carried out to identify reaction intermediates, the temperature at which various intermediates form, and the average domain size of the Mo{sub 2}N products. Materials were synthesized in bulk and further characterized by XRD, HRTEM, XPS, and BET. - Highlights: • Facile synthesis of γ-Mo2N and α-Mo2C with surface area exceeding 100 m{sup 2}/g. • Sacrificial support method was used to achieve these high surface areas. • Materials can serve as catalysts or supports in (electro)chemical processes.

  9. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35 mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC.

  10. Excess surface area in bioelectrochemical systems causes ion transport limitations.

    PubMed

    Harrington, Timothy D; Babauta, Jerome T; Davenport, Emily K; Renslow, Ryan S; Beyenal, Haluk

    2015-05-01

    We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200 mM increased current linearly up to a total of +273% vs. 0 mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200 mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steady-state current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant. © 2014 Wiley Periodicals, Inc.

  11. Solvothermal synthesis of ceria nanoparticles with large surface areas

    SciTech Connect

    Hosokawa, S.; Shimamura, K.; Inoue, M.

    2011-11-15

    Highlights: {yields} Thermal decomposition of Ce(C{sub 7}H{sub 15}COO){sub 3}.xH{sub 2}O synthesized by solvothermal method. {yields} CeO{sub 2} having an extremely large surface area of 180 m{sup 2}/g. {yields} High catalytic activity of Ru catalyst supported on the CeO{sub 2} having high surface area. -- Abstract: Ceria nanoparticles were obtained by the calcination of precursors synthesised via the solvothermal reaction of cerium acetate. The CeO{sub 2} samples obtained by the thermal decomposition of Ce(C{sub 7}H{sub 15}COO){sub 3}.xH{sub 2}O synthesised by solvothermal reaction in 1,4-butanediol in the presence of octanoic acid had an extremely large surface area of 180 m{sup 2}/g. The Ru catalyst supported on this CeO{sub 2} sample showed a high catalytic activity for benzyl alcohol oxidation.

  12. Excess Surface Area in Bioelectrochemical Systems Causes ion Transport Limitations

    SciTech Connect

    Harrington, Timothy D.; Babauta, Jerome T.; Davenport, Emily K.; Renslow, Ryan S.; Beyenal, Haluk

    2015-05-01

    We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200mM increased current linearly up to a total of þ273% vs. 0mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steadystate current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant.

  13. Determination of Glacier Surface Area Using Spaceborne SAR Imagery

    NASA Astrophysics Data System (ADS)

    Fang, L.; Maksymiuk, O.; Schmitt, M.; Stilla, U.

    2013-04-01

    Glaciers are very important climate indicators. Although visible remote sensing techniques can be used to extract glacier variations effectively and accurately, the necessary data are depending on good weather conditions. In this paper, a method for determination of glacier surface area using multi-temporal and multi-angle high resolution TerraSAR-X data sets is presented. We reduce the "data holes" in the SAR scenes affected by radar shadowing and specular backscattering of smooth ice surfaces by combining the two complementary different imaging geometries (from ascending and descending satellite tracks). Then, a set of suitable features is derived from the intensity image, the texture information generated based on the gray level co-occurrence matrix (GLCM), glacier velocity estimated by speckle tracking, and the interferometric coherence map. Furthermore, the features are selected by 10-foldcross- validation based on the feature relevance importance on classification accuracy using a Random Forests (RF) classifier. With these most relevant features, the glacier surface is discriminated from the background by RF classification in order to calculate the corresponding surface area.

  14. Estimation of surface runoff and water-covered area during filling of surface microrelief depressions

    NASA Astrophysics Data System (ADS)

    Hansen, B.

    2000-05-01

    During the filling of surface microrelief depressions the precipitation excess (precipitation minus infiltration and interception) is divided between surface storage and runoff, i.e. runoff starts before the surface depressions are filled. Information on the division of precipitation excess is needed for modelling surface runoff during the filling of surface depressions. Furthermore, information on the surface of the area covered with water is needed for calculating infiltration of water stored in soil surface depressions. Thirty-two soil surface microreliefs were determined in Danish erosion study plots. The slope was c. 10% for all plots. Data were treated initially by removing the slope, after which 20 artificial slopes (1-20%) were introduced producing 640 new data sets. Runoff during filling of the microrelief storage was calculated for each of the 640 data sets using a model developed for calculating surface storage and runoff from grid elevation measurements. Runoff started immediately after the first addition of water for all data sets. On a field scale, however, runoff has to travel some distance as overland flow and storage in smaller and larger depressions below the runoff initiation point must be taken into consideration. The runoff increases by intermittent steps. Whenever a depression starts to overflow to the border of the plot, the runoff jumps accordingly. In spite of the jumps, the distribution between surface storage and runoff was closely related to the quotient between precipitation excess and depression storage capacity. Surface area covered with water was exponentially related to the amount of water stored in surface depressions. Models for calculating surface storage and runoff from grid elevation measurements are cumbersome and require time-consuming measurements of the soil surface microrelief. Therefore, estimation from roughness indices requiring fewer measurements is desirable. New improved equations for such estimations are suggested.

  15. A new testing protocol for zirconia dental implants.

    PubMed

    Sanon, Clarisse; Chevalier, Jérôme; Douillard, Thierry; Cattani-Lorente, Maria; Scherrer, Susanne S; Gremillard, Laurent

    2015-01-01

    Based on the current lack of standards concerning zirconia dental implants, we aim at developing a protocol to validate their functionality and safety prior their clinical use. The protocol is designed to account for the specific brittle nature of ceramics and the specific behavior of zirconia in terms of phase transformation. Several types of zirconia dental implants with different surface textures (porous, alveolar, rough) were assessed. The implants were first characterized in their as-received state by Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), X-Ray Diffraction (XRD). Fracture tests following a method adapted from ISO 14801 were conducted to evaluate their initial mechanical properties. Accelerated aging was performed on the implants, and XRD monoclinic content measured directly at their surface instead of using polished samples as in ISO 13356. The implants were then characterized again after aging. Implants with an alveolar surface presented large defects. The protocol shows that such defects compromise the long-term mechanical properties. Implants with a porous surface exhibited sufficient strength but a significant sensitivity to aging. Even if associated to micro cracking clearly observed by FIB, aging did not decrease mechanical strength of the implants. As each dental implant company has its own process, all zirconia implants may behave differently, even if the starting powder is the same. Especially, surface modifications have a large influence on strength and aging resistance, which is not taken into account by the current standards. Protocols adapted from this work could be useful. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. In vivo evaluation of zirconia ceramic in the DexAide right ventricular assist device journal bearing.

    PubMed

    Saeed, Diyar; Shalli, Shanaz; Fumoto, Hideyuki; Ootaki, Yoshio; Horai, Tetsuya; Anzai, Tomohiro; Zahr, Roula; Horvath, David J; Massiello, Alex L; Chen, Ji-Feng; Dessoffy, Raymond; Catanese, Jacquelyn; Benefit, Stephen; Golding, Leonard A R; Fukamachi, Kiyotaka

    2010-06-01

    Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14-91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device-induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.

  17. Three generations of zirconia: 
From veneered to monolithic. Part II.

    PubMed

    Stawarczyk, Bogna; Keul, Christin; Eichberger, Marlis; Figge, David; Edelhoff, Daniel; Lümkemann, Nina

    2017-01-01

    This article presents the historical development of the different generations of zirconia and their range of indications, from veneered to monolithic zirconia restorations. While Part I concentrated on detailed information about the development of zirconia for dental use and the mechanical and optical properties, Part II deals with the resulting guidelines for working with the relevant generations by summarizing the correct cementation procedure. Furthermore, this part also focuses on translucency measurements for better characterization and understanding of the different materials. The results obtained from measuring light transmission and contrast ratio are compared and discussed in detail, with the aid of clinical photographs. Finally, the reader is given practice-relevant recommendations for different areas of clinical use of the zirconia generations along with advice on how to process them appropriately.

  18. Performance of Zirconia for Dental Healthcare

    PubMed Central

    Silva, Nelson R.F.A.; Sailer, Irena; Zhang, Yu; Coelho, Paulo G.; Guess, Petra C.; Zembic, Anja; Kohal, Ralf J.

    2010-01-01

    The positive results of the performance of zirconia for orthopedics devices have led the dental community to explore possible esthetical and mechanical outcomes using this material. However, questions regarding long-term results have opened strong and controversial discussions regarding the utilization of zirconia as a substitute for alloys for restorations and implants. This narrative review presents the current knowledge on zirconia utilized for dental restorations, oral implant components, and zirconia oral implants, and also addresses laboratory tests and developments, clinical performance, and possible future trends of this material for dental healthcare.

  19. In-vitro bioactivity of zirconia doped borosilicate glasses

    SciTech Connect

    Samudrala, Rajkumar; Azeem, P. Abdul E-mail: drazeem2002@yahoo.com

    2015-06-24

    Glass composition 31B{sub 2}O{sub 3}-20SiO{sub 2}-24.5Na{sub 2}O-(24.5-x) CaO-xZrO{sub 2} x=1,2,3,4,5 were prepared by melt-quenching Technique. The formation of hydroxyapatite layer on the surface of glasses after immersion in simulated body fluid (SBF) was explored through XRD, Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM-EDX) analyses. In this report, we observed that hydroxyapatite formation for 5days of immersion time. Also observed that with increasing the immersion time up to 15days, higher amount of hydroxyapatite layer formation on the surface of glasses. The varying composition of zirconia in glass samples influences shown by XRD, FTIR studies. The present results indicate that, in-vitro bioactivity of glasses decreased with increasing zirconia incorporation.

  20. Influence of the monoclinic and tetragonal zirconia phases on the water gas shift reaction. A theoretical study.

    PubMed

    Cerón, María Luisa; Herrera, Barbara; Araya, Paulo; Gracia, Francisco; Toro-Labbé, Alejandro

    2013-07-01

    We present a theoretical study of the water gas shift reaction taking place on zirconia surfaces modeled by monoclinic and tetragonal clusters. In order to understand the charge transfer between the active species, in this work we analyze the influence of the geometry of monoclinic and tetragonal zirconia using reactivity descriptors such as electronic chemical potential (μ), charge transfer (ΔN) and molecular hardness (η). We have found that the most preferred surface is tetragonal zirconia (tZrO2) indicating also that low charge transfer systems will generate less stable intermediates, that will allow to facilitate desorption process.

  1. Electrical conductivity of zirconia and yttrium-doped zirconia from Indonesian local zircon as prospective material for fuel cells

    NASA Astrophysics Data System (ADS)

    Apriany, Karima; Permadani, Ita; Syarif, Dani G.; Soepriyanto, Syoni; Rahmawati, Fitria

    2016-02-01

    In this research, zirconium dioxide, ZrO2, was synthesized from high-grade zircon sand that was founded from Bangka Island, Sumatra, Indonesia. The zircon sand is a side product of Tin mining plant industry. The synthesis was conducted by caustic fusion method with considering definite stoichiometric mole at every reaction step. Yttrium has been doped into the prepared zirconia by solid state reaction. The prepared materials were then being analyzed by X-ray diffraction equipped with Le Bail refinement to study its crystal structure and cell parameters. Electrical conductivity was studied through impedance measurement at a frequency range of 20 Hz- 5 MHz. Morphological analysis was conducted through Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX) for elemental analysis. The results show that the prepared yttrium stabilized zirconia, YSZ, was crystallized in the cubic structure with a space group of P42/NMC. The sintered zirconia and yttrium stabilized zirconia at 8 mol% of yttrium ions (8YSZ) show dense surface morphology with a grain size less than 10 pm. Elemental analysis on the sintered zirconia and 8YSZ show that sintering at 1500°C could eliminate the impurities, and the purity became 81.30%. Impedance analysis shows that ZrO2 provide grain and grain boundary conductivity meanwhile 8YSZ only provide grain mechanism. The yttrium doping enhanced the conductivity up to 1.5 orders. The ionic conductivity of the prepared 8YSZ is categorized as a good material with conductivity reach 7.01 x10-3 at 700 °C. The ionic conductivities are still lower than commercial 8YSZ at various temperature. It indicates that purity of raw material might significantly contribute to the electrical conductivity.

  2. Alumina-Reinforced Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Bansal, Narottam P.

    2003-01-01

    Alumina-reinforced zirconia composites, used as electrolyte materials for solid oxide fuel cells, were fabricated by hot pressing 10 mol percent yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina particulates and platelets each containing 0 to 30 mol percent alumina. Major mechanical and physical properties of both particulate and platelet composites including flexure strength, fracture toughness, slow crack growth, elastic modulus, density, Vickers microhardness, thermal conductivity, and microstructures were determined as a function of alumina content either at 25 C or at both 25 and 1000 C. Flexure strength and fracture toughness at 1000 C were maximized with 30 particulate and 30 mol percent platelet composites, respectively, while resistance to slow crack growth at 1000 C in air was greater for 30 mol percent platelet composite than for 30 mol percent particulate composites.

  3. In vitro shear bond strength of two self-adhesive resin cements to zirconia.

    PubMed

    Qeblawi, Dana M; Campillo-Funollet, Marc; Muñoz, Carlos A

    2015-02-01

    Although the use of anatomic-contour zirconia restorations has expanded in the recent past, disagreement still exists as to reliable cementation techniques and materials. The purpose of this in vitro study was to compare the immediate and artificially aged shear bond strength of 2 commercially available self-adhesive resin cements to zirconia: one with silica coating and silanation as a zirconia surface treatment and the other contained a phosphate monomer, which eliminated the need for a separate primer. Sixty composite resin rods (2.5 mm in diameter and 3 mm in length) were fabricated from a nano-optimized composite resin by using a polypropylene mold, then light polymerized with a light-emitting diode. zirconia plates (10×10×4mm) were sectioned from an yttrium-stabilized zirconia puck, sintered, and then mounted in autopolymerizing acrylic resin custom tray material. Composite resin rods were cemented to the zirconia plates with 2 different cements. The surface treatment of zirconia followed the manufacturers' instructions for each cement. The specimens were tested for shear bond strength at 3 aging conditions: immediate, after 24 hours of moist storage, and after 30 days of moist storage with 10000 thermocycles. Specimens were loaded to failure in a universal testing machine, and the data were analyzed with 2-way ANOVA (α=.05). Weibull parameters (modulus and characteristic strength) also were calculated for each group. Two-way ANOVA revealed that only the aging condition significantly affected the bond strength to zirconia. The cement and the interaction of the cement and aging did not significantly affect the shear bond strength to zirconia. The highest bond strength for both cements was achieved at 24 hours, whereas the lowest bond strength values were recorded in the immediate groups. No significant differences in bond strength to zirconia were observed between a cement with a silane priming step and an methacryloxydecyl dihydrogen phosphate

  4. Comparison of shear bond strength of orthodontic brackets using various zirconia primers

    PubMed Central

    Lee, Ji-Yeon; Kim, Jin-Seok

    2015-01-01

    Objective The aim of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded to zirconia surfaces using three different zirconia primers and one silane primer, and subjected to thermocycling. Methods We designed 10 experimental groups following the surface treatment and thermocycling. The surface was treated with one of the following method: no-primer (NP), Porcelain Conditioner (PC), Z-PRIME Plus (ZP), Monobond Plus (MP) and Zirconia Liner Premium (ZL) (n=20). Then each group was subdivided to non-thermocycled and thermocycled groups (NPT, PC, ZPT, MPT, ZLT) (n=10). Orthodontic brackets were bonded to the specimens using Transbond™ XT Paste and light cured for 15 s at 1,100 mW/cm2. The SBS was measured at a 1 mm/min crosshead speed. The failure mode was assessed by examination with a stereomicroscope and the amount of bonding resin remaining on the zirconia surface was scored using the modified adhesive remnant index (ARI). Results The SBS of all experimental groups decreased after thermocycling. Before thermocycling, the SBS was ZL, ZP ≥ MP ≥ PC > NP but after thermocycling, the SBS was ZLT ≥ MPT ≥ ZPT > PCT = NPT (p > 0.05). For the ARI score, both of the groups lacking primer (NP and NPT) displayed adhesive failure modes, but the groups with zirconia primers (ZP, ZPT, MP, MPT, ZL, and ZLT) were associated with mixed failure modes. Conclusions Surface treatment with a zirconia primer increases the SBS relative to no-primer or silane primer application between orthodontic brackets and zirconia prostheses. PMID:26258062

  5. Zirconia-molybdenum disilicide composites

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.

    1991-01-01

    Compositions of matter comprised of molybdenum disilicide and zirconium oxide in one of three forms: pure, partially stabilized, or fully stabilized and methods of making the compositions. The stabilized zirconia is crystallographically stabilized by mixing it with yttrium oxide, calcium oxide, cerium oxide, or magnesium oxide and it may be partially stabilized or fully stabilized depending on the amount of stabilizing agent in the mixture.

  6. High surface area aerogels for energy storage and efficiency

    NASA Astrophysics Data System (ADS)

    Maloney, Ryan Patrick

    ADAI are demonstrated in a third-generation prototypical thermoelectric generator for automotive waste heat recovery. The second chapter then details two different aerogel-based materials for electrochemical energy storage. It begins with lithium titanate aerogel, which takes advantage of the high surface area of the aerogel morphology to display a batt-cap behavior. This should allow the lithium titanate aerogel to perform at higher rates than would normally be expected for the bulk oxide material. Additionally, the flexibility of the sol-gel process is demonstrated through the incorporation of electrically conductive high-surface area exfoliated graphite nanoplatelets in the oxide. The last section describes the characterization of a LiMn2O 4 spinel coated carbon nanofoam in a non-aqueous electrolyte. The short diffusion path, high surface area and intimately wired architecture of the nanofoam allows the oxide to retain its capacity at significantly higher rates when compared with literature values for the bulk oxide. Additionally, the nanometric length scale improves cycle life, and the high surface area dramatically increases the insertion capacity by providing a higher concentration of surface defects. Taken together, it is clear that aerogels are an extremely attractive class of material for applications pertaining to energy and efficiency, and further research in this area will provide valuable solutions for pressing societal needs. (Abstract shortened by UMI.).

  7. Acid and alkali etching of grit blasted zirconia: Impact on adhesion and osteogenic differentiation of MG63 cells in vitro.

    PubMed

    Gruber, Reinhard; Hedbom, Erik; Bosshardt, Dieter D; Heuberger, Roman; Buser, Daniel

    2012-01-01

    There is a need for evaluating zirconia surface modifications and their potential impact on the biological response of osteogenic cells. Grit blasted zirconia discs were either left untreated or underwent acid or alkaline etching. Adhesion and osteogenic differentiation of MG63 cells was determined after one week of culture. The macro-scaled roughness of the grit blasted zirconia discs, independent of the surface treatment, was within a narrow range and only slightly smoother than titanium discs. However, the alkaline- and acid-etching led to an increase of the micro-roughness of the surface. The surface modifications had no effect on cell spreading and did not cause significant change in the expression of differentiation markers. Thus, in this respective setting, morphologic changes observed upon treatment of grit blasted zirconia discs with acid or alkaline do not translate into changes in MG63 cell adhesion or differentiation and are comparable to findings with anodized titanium discs.

  8. The Effect of Femtosecond Laser Treatment on the Effectiveness of Resin-Zirconia Adhesive: An In Vitro Study

    PubMed Central

    Vicente Prieto, María; Gomes, Ana Luisa Caseiro; Montero Martín, Javier; Alvarado Lorenzo, Alfonso; Seoane Mato, Vicente; Albaladejo Martínez, Alberto

    2016-01-01

    Introduction: When aesthetics is compromised, dental ceramics are excellent materials for dental restorations; owing to their optical properties and biocompatibility, zirconia ceramics are particularly interesting. Self-adhesive resin cements are the most suitable for bonding to zirconia ceramics, but traditional adhesive chemistry is ineffective and surface treatments are required to improve the adhesive bonding between resin and zirconia. The aim of this study was to evaluate the effect of femtosecond laser treatment on the shear bond strength (SBS) of self-adhesive resin cement on zirconia surfaces and to contrast it with other different surface conditioning methods. Methods: Sixty square-shaped zirconia samples were divided randomly into four groups (n = 15) according to their surface conditioning method: the NT group - no surface treatment; the APA25 group - airborne abrasion with 25 μm alumina particles; the TSC group - tribochemical silica coating, and the FS group - femtosecond laser irradiation (800 nm, 4 mJ, 40 fs/pulse, 1 kHz). Self-adhesive resin cements were bonded at the centre of samples, and after 72 hours, they were tested for SBS with a universal testing machine at a crosshead speed of 0.5 mm/min, until fracture. Five zirconia surfaces for each group were subjected to a surface morphology analysis by scanning electron microscopy (SEM). The failure modes were noted and a third of the specimens were prepared to morphological analysis. Results: The NT group showed lower SBS values than the other groups. Femtosecond laser treatment demonstrated higher values than the control and APA25 groups and similar values to those of the TSC group. In the APA25 group, the surface conditioning method had values close to those of the TSC group, but lower than those obtained with femtosecond laser treatment. Conclusion: The treatment of zirconia with femtosecond laser irradiation created a consistent and profound surface roughness, improving the adhesive

  9. Partially stabilized zirconia piston bowl reliability

    SciTech Connect

    Hartsock, D.L.

    1987-10-01

    The Weibull based ''Simplified Structural Ceramic Design Technique'' was used to calculate the reliability of a partially stabilized zirconia (PSZ) piston bowl design. The details of the method and a set of sample calculations are presented. Test results of the piston bowl showed cracks in regions which had a high calculated probability of failure. In addition cracks developed in a region of high compressive/shear stress. Since Weibull reliability analysis only uses tensile stresses this area did not have a high calculated probability of failure. Several hypotheses are presented for the mode of failure in this region. The simplified technique was used to predict what the necessary material properties would have to be for successful PSZ insert of the design shown.

  10. Tailoring the structural and optical parameters of zirconia nanoparticles via silver

    NASA Astrophysics Data System (ADS)

    Rani, Saruchi; Verma, Surbhi; Kumar, Sushil

    2017-08-01

    Silver-doped zirconia nanoparticles/thin films with different doping concentrations 0.03, 0.05 and 0.07 mol% were synthesized by sol-gel route followed by spin coating. Zirconium (IV) chloride and silver nitrate were used as precursors. The prepared powdered samples and thin films were annealed in a programmable furnace at 650 °C for 3 h. XRD spectra showed prominent tetragonal phase of zirconia and cubic phase of silver nanoparticles. Structural parameters such as crystallite size, lattice constants, micro-strain, dislocation density, specific surface area and the number of unit cell in a particle were evaluated. FTIR spectra confirmed the expected functional groups present in the annealed samples. Optical absorption spectra of Ag-doped ZrO2 thin films established the tuning of band-gap with dopant concentration. PL spectra exhibited two broad blue emission bands centered at 340 and 475 nm. TG-DTA thermal analysis of as-prepared sample was also carried out.

  11. Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process.

    PubMed

    Seo, Dong Seok; Chae, Hak Cheol; Lee, Jong Kook

    2015-08-01

    Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation.

  12. Effect of particle deposition parameters on silica coating of zirconia using a chairside air-abrasion device.

    PubMed

    Ozcan, Mutlu; Raadschelders, John; Vallittu, Pekka; Lassilla, Lippo

    2013-06-01

    To evaluate the effect of nozzle distance, nozzle angle, and deposition duration on the silica content attained on zirconia by air abrasion. Disk-shaped zirconia (LAVA, 3M ESPE) (diameter: 10 mm, thickness: 2 mm) specimens (N = 54) were obtained. They were wet-ground finished using 600-, 800-, and 1200-grit silicone carbide abrasive papers in sequence and ultrasonically cleaned. The specimens were mounted in a specially designed apparatus that allowed the chairside air-abrasion device to be operated under standard conditions. Alumina-coated silica particles (CoJet Sand, 3M ESPE) were deposited on the zirconia disk surfaces varying the following parameters: a) nozzle distance (2, 5, 10 mm), and b) deposition duration (5, 13, 20 s) at two nozzle angles (45 and 90 degrees) under 2.5 bar pressure at three locations on each ceramic disk. The specimen surfaces were then gently air dried for 20 s. Silica content in weight percentage (wt%) was measured from 3 surfaces on each disk using Energy Dispersive X-ray Spectroscopy (EDS) (150X) in an area of 0.8 mm x 0.6 mm (n = 3 per group). Surface topographies were evaluated using SEM. Data were analyzed using ANOVA and Tukey's tests (α = 0.05). Nozzle angle (p = 0.003) and deposition duration (p = 0.03) significantly affected the results, but nozzle distance (p = 0.569) did not. A significantly higher amount of silica (wt%) was achieved when the nozzle angle was 45 degrees to the surface in all distance-duration combinations (16.7 to 28.2 wt%) compared to the 90-degree nozzle angle (10.7 to 18.6 wt%) (p < 0.001). The silica amount was significantly higher after 20-s deposition duration than after 13 s (p < 0.05). EDS analysis demonstrated not only Si but also Al, Zr, and O traces on the substrate. SEM images indicated that deposition at a nozzle distance of 2 mm often created cavitations in zirconia. Effective silica deposition using a charside air-abrasion device can be achieved when the nozzle is held at 45 degrees to the

  13. Nano-Engineered Cubic Zirconia for Orthopaedic Implant Applications

    NASA Astrophysics Data System (ADS)

    Namavar, F.; Rubinstein, A.; Sabirianov, R.; Thiele, G.; Sharp, J.; Pokharel, U.; Namavar, R.; Garvin, K.

    2012-02-01

    Osseointegration failure of the prosthesis prevents long-term stability, which contributes to pain, implant loosening, and infection that usually necessitates revision surgery. Cell attachment and spreading in vitro is generally mediated by adhesive proteins such as fibronectin and vitronectin. We designed and produced pure cubic zirconia (ZrO2) ceramic coatings by ion beam assisted deposition (IBAD) with nanostructures comparable to the size of proteins. Our ceramic coatings exhibit high hardness and a zero contact angle with serum. In contrast to Hydroxyapatite (HA), nano-engineered zirconia films possess excellent adhesion to all orthopaedic materials. Adhesion and proliferation experiments were performed with a bona fide mesenchymal stromal cells cell line (OMA-AD). Our experimental results indicated that nano-engineered cubic zirconia is superior in supporting growth, adhesion, and proliferation. We performed a comparative analysis of adsorption energies of the FN fragment using quantum mechanical calculations and Monte Carlo simulation on both types of surfaces: smooth and nanostructured. We have found that the initial FN fragment adsorbs significantly stronger on the nanostructured surface than on the smooth surface.

  14. Fabrication of large area nanostructures with surface modified silica spheres

    NASA Astrophysics Data System (ADS)

    Kang, Kwang-Sun

    2014-03-01

    Surface modification of silica spheres with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) has been performed at ambient condition. However, the FTIR spectra and field emission scanning electron microscope (FESEM) images show no evidence of the surface modification. The reaction temperatures were varied from 60 to 80 °C with various reaction periods. Small absorption shoulder of the CO stretching vibration was at 1700 cm-1, and slightly increased with the increase of the reaction time at 60 °C. The clear absorption peak appeared at 1698 cm-1 for the spheres reacted for 80 min at 70 °C and shifted toward 1720 cm-1 with the increase the reaction time. Strong absorption peak showed at 1698 cm-1 and shifted toward 1725 cm-1 with the increase of the reaction time at 80 °C. The spheres were dispersed to methanol and added photoinitiator (Irgacure-184). The solution was poured to a patterned glass substrate and exposed to the 254 nm UV-light during a self-assembly process. A large area and crack-free silica sphere film was formed. To increase the mechanical stability, a cellulose acetate solution was spin-coated to the film. The film was lift-off from the glass substrate to analyze the surface nanostructures. The surface nanostructures were maintained, and the film is stable enough to use as a mold to duplicate the nanopattern and flexible.

  15. Surface area-dependent second harmonic generation from silver nanorods.

    PubMed

    Ngo, Hoang Minh; Luong, Thanh Tuyen; Ledoux-Rak, Isabelle

    2016-08-17

    The nonlinear optical (NLO) properties of metallic nanoparticles strongly depend on their size and shape. Metallic gold nanorods have already been widely investigated, but other noble metals could also be used for nanorod fabrication towards applications in photonics. Here we report on the synthesis and NLO characterization of silver nanorods (AgNRs) with controllable localized surface plasmon resonance. We have implemented an original, one-step and seedless synthesis method, based on a spontaneous particle growth technique in the presence of polyvinylpyrrolidone (PVP) as a capping agent. Colloidal solutions of AgNRs with various aspect ratios (5.0; 6.3; 7.5; 8.2 and 9.7) have been obtained and characterized using Harmonic light scattering (HLS) at 1064 nm, in order to investigate their quadratic NLO properties. From HLS experiments, we demonstrate that hyperpolarizability (β) values of AgNRs display a strong dependence on their surface area.

  16. Surface Areas and Morphology of Thin Ice Films

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun; Keyser, Leon F.; Timonen, Raimo S.

    1996-01-01

    Thin ice films formed by deposition from the vapor phase in a fast flow-tube reactor have been used to simulate polar stratospheric cloud surfaces in order to obtain laboratory data on uptake and heterogeneous reaction rates. Surface areas are determined from BET (Brunauer, Emmett, and Teller) analysis of gas adsorption isotherms. The results for ices prepared at 196 K or 77 K are consistent with previous data on thicker ice films. Environmental scanning electron microscopy is used to obtain particle sizes and shapes, and to investigate the morphology of the ices on borosilicate or silicon windows. In addition, the uptake of HCI on ice films prepared at 196 K is investigated. The results suggest that the layer model we have previously developed for analysis of uptake and heterogeneous reaction rates on ice films is valid. Detailed information will be presented at the conference.

  17. Biomechanical and histological evaluation of the osseointegration capacity of two types of zirconia implant

    PubMed Central

    Han, Jian-min; Hong, Guang; Lin, Hong; Shimizu, Yoshinaka; Wu, Yuhan; Zheng, Gang; Zhang, Hongyu; Sasaki, Keiichi

    2016-01-01

    The purpose of this study was to evaluate the biomechanical and histological behavior of a ceria-stabilized zirconia–alumina nanocomposite (NanoZr) in comparison with that of 3 mol% yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) in Sprague Dawley rats. Cylindrical NanoZr and 3Y-TZP implants (diameter 1 mm, length 2 mm) were used. Implant-surface morphology and surface roughness were determined by scanning white-light interferometry and scanning electron microscopy, respectively. The cylindrical zirconia implants were placed at the distal edge of the femur of Sprague Dawley rats. At weeks 2, 4, and 8, the interfacial shear strength between implant and bone was measured by push-in test. Histological analysis was performed using hard-tissue sections. Bone–implant contact (BIC), the thickness of new bone around the implant within the bone marrow area, and osteoclast numbers were evaluated. The average surface roughness of 3Y-TZP (Sa 0.788 μm) was significantly higher than that of NanoZr (Sa 0.559 μm). The shear strengths of 3Y-TZP and NanoZr were similar at 2 weeks, but at 4 and 8 weeks the shear strength of NanoZr was higher than that of 3Y-TZP. The average BIC values within the bone marrow area for 3Y-TZP and NanoZr were 25.26% and 31.51% at 2 weeks, 46.78% and 38% at 4 weeks, and 47.88% and 56.81% at 8 weeks, respectively. The average BIC values within the cortical area were 38.86% and 58.42% at 2 weeks, 66.82% and 57.74% at 4 weeks, and 79.91% and 78.97% at 8 weeks, respectively. The mean BIC value did not differ significantly between the two zirconia materials at any time point. The NanoZr implants were biocompatible, capable of establishing close BIC, and may be preferred for metal-free dental implants. PMID:27994456

  18. Skeletal muscle area correlates with body surface area in healthy adults.

    PubMed

    Yoshizumi, Tomoharu; Shirabe, Ken; Nakagawara, Hidekazu; Ikegami, Toru; Harimoto, Norifumi; Toshima, Takeo; Yamashita, Yo-Ichi; Ikeda, Tetsuo; Soejima, Yuji; Maehara, Yoshihiko

    2014-03-01

    Depletion of skeletal muscle mass (sarcopenia) predicts survival in patients with cancer or liver cirrhosis. Recently, many reports have used computed tomography (CT) to measure muscle area to define sarcopenia. However, the definition of sarcopenia using CT has not been fully determined. The aim of this study was to establish formulae to calculate the standard area of skeletal muscle. Forty-five healthy adults (24 men and 21 women, aged 21-66 years) who wished to donate part of their liver for transplantation underwent CT. Cross-sectional areas (cm(2) ) of skeletal muscle were measured at the caudal end of the third lumbar vertebra. Regression analysis was performed to establish formulae to calculate the standard area of skeletal muscle. A validation conducted on 30 other healthy adults was performed to check the accuracy of formulae. Men had a median skeletal muscle area of 155.0 cm(2) (range, 114.0-203.0), compared with 111.7 cm(2) (range, 89.8-139.3) in women (P < 0.001). Furthermore, skeletal muscle area significantly correlated with body surface area (BSA) in men (P < 0.0001, r(2)  = 0.60) and women (P < 0.0001, r(2)  = 0.78). The formulae to calculate skeletal muscle area were 126.9 × BSA - 66.2 in men and 125.6 × BSA - 81.1 in women. The estimated muscle area significantly correlated with actual muscle area in men (P = 0.003, r(2)  = 0.64) and women (P = 0.0001, r(2)  = 0.70). Sarcopenia can be defined by the difference between measured data and calculated data using our new formulae. © 2013 The Japan Society of Hepatology.

  19. Deposition of crystalline hydroxyapatite nano-particle on zirconia ceramic: a potential solution for the poor bonding characteristic of zirconia ceramics to resin cement.

    PubMed

    Azari, Abbas; Nikzad, Sakineh; Yazdani, Arash; Atri, Faezeh; Fazel Anvari-Yazdi, Abbas

    2017-07-01

    The poor bonding strength of zirconia to different dental substrates is one of the challenging issues in restorative dentistry. Hydroxyapatite is an excellent biocompatible material with fine bonding properties. In this study, it was hypothesized that hydroxyapatite coating on zirconia would improve its bond strength. Forty-five zirconia blocks were prepared and randomly divided into three groups: hydroxyapatite coating, sandblasting, and no preparation (control). The blocks were bonded to cement and the micro-shear bond strength was measured following load application. The bond strength values were analyzed with the Kruskal-Wallis test in 3 groups and paired comparisons were made using the Mann-Whitney U test. The failure patterns of the specimens were studied by a stereomicroscope and a scanning electron microscope and then analyzed by the chi-square test (significance level = 0.05). Deposition of hydroxyapatite on the zirconia surface significantly improved its bond strength to the resin cement in comparison with the control specimens (p < 0.0001). Also, the bond strength was similar to the sandblasted group (p = 0.34). The sandblasted and control group only showed adhesive failure, but the hydroxyapatite coated group had mixed failures, indicating the better quality of bonding (p < 0.0001). As a final point, hydroxyapatite coating on the zirconia surface improved the bond strength quality and values.

  20. Thermodynamic surface system of static black holes and area law

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Huang, Yong-Chang

    2016-11-01

    We propose a new picture of black holes through a special holographic screen. This holographic screen contains all the degrees of freedom of a black hole. We find that this holographic screen is similar to the ordinary thermodynamic surface system. Meanwhile, through the “white-wall box” and the formula of sound velocity, we find some similarities between gravitons and photons. We further assume that such a holographic screen is a kind of Bose-Einstein condensate of gravitons. Through this assumption and those similarities, we finally get the area law of static black holes. Supported by National Natural Science Foundation of China (11275017, 11173028)

  1. Metal-organic framework materials with ultrahigh surface areas

    DOEpatents

    Farha, Omar K.; Hupp, Joseph T.; Wilmer, Christopher E.; Eryazici, Ibrahim; Snurr, Randall Q.; Gomez-Gualdron, Diego A.; Borah, Bhaskarjyoti

    2015-12-22

    A metal organic framework (MOF) material including a Brunauer-Emmett-Teller (BET) surface area greater than 7,010 m.sup.2/g. Also a metal organic framework (MOF) material including hexa-carboxylated linkers including alkyne bond. Also a metal organic framework (MOF) material including three types of cuboctahedron cages fused to provide continuous channels. Also a method of making a metal organic framework (MOF) material including saponifying hexaester precursors having alkyne bonds to form a plurality of hexa-carboxylated linkers including alkyne bonds and performing a solvothermal reaction with the plurality of hexa-carboxylated linkers and one or more metal containing compounds to form the MOF material.

  2. Hydroetching of high surface area ceramics using moist supercritical fluids

    DOEpatents

    Fryxell, Glen; Zemanian, Thomas S.

    2004-11-02

    Aerogels having a high density of hydroxyl groups and a more uniform pore size with fewer bottlenecks are described. The aerogel is exposed to a mixture of a supercritical fluid and water, whereupon the aerogel forms a high density of hydroxyl groups. The process also relaxes the aerogel into a more open uniform internal structure, in a process referred to as hydroetching. The hydroetching process removes bottlenecks from the aerogels, and forms the hydrogels into more standard pore sizes while preserving their high surface area.

  3. Altered red blood cell surface area in hereditary xerocytosis.

    PubMed

    Sauberman, N; Fairbanks, G; Lutz, H U; Fortier, N L; Snyder, L M

    1981-08-10

    Hereditary xerocytes appear larger than normal red cells in scanning electron micrographs and exhibit a higher ghost packing volume. The major chemical components--protein, phosphorus, cholesterol and sialic acid--are increased uniformly, as are all polypeptides visible on gel electrophoresis patterns of xerocyte membranes. These data are consistent with a xerocyte surface area 15 to 25% above normal. Certain clinical anomalies common to this disorder, including unexpectedly low reticulocyte count and 2,3-diphosphoglycerate level, are discussed in the light of the present findings.

  4. High surface area graphene-supported metal chalcogenide assembly

    DOEpatents

    Worsley, Marcus A.; Kuntz, Joshua; Orme, Christine A.

    2016-04-19

    A composition comprising at least one graphene-supported assembly, which comprises a three-dimensional network of graphene sheets crosslinked by covalent carbon bonds, and at least one metal chalcogenide compound disposed on said graphene sheets, wherein the chalcogen of said metal chalcogenide compound is selected from S, Se and Te. Also disclosed are methods for making and using the graphene-supported assembly, including graphene-supported MoS.sub.2. Monoliths with high surface area and conductivity can be achieved. Lower operating temperatures in some applications can be achieved. Pore size and volume can be tuned.

  5. Unique sharp photoluminescence of size-controlled sonochemically synthesized zirconia nanoparticles.

    PubMed

    Manoharan, Divinah; Loganathan, Aswaghosh; Kurapati, Vishista; Nesamony, Victor Jaya

    2015-03-01

    The present study explores the features of tetragonally stabilized polycrystalline zirconia nanophosphors prepared by a sonochemistry based synthesis from zirconium oxalate precursor complex. The sonochemically prepared pristine zirconia, 3 mol%, 5 mol% and 8 mol% yttrium doped zirconia nanophosphors were characterized using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The reaction mechanism of formation of zirconia nanophosphors is discussed in detail. The probable sonochemical formation mechanism is being proposed. Stabilization of tetragonal phase of pristine zirconia even at room temperature was effectively established by controlling the particle size using ultrasonic waves. Improved phase purity and good surface morphology of the nanophosphors is being achieved via sonochemical route. FE-SEM micrographs reveal that the nanoparticles have uniform spherical shape and size. The narrow particle size distribution (∼15-25 nm) of the zirconia nanoparticles was found from FE-SEM statistical analysis and further confirmed by TEM. Zirconia nanophosphors exhibit a wide energy band gap and which was found to vary with yttrium dopant concentration. The highlight of the present study is the synthesis of novel nanocrystalline ZrO₂ and Y-ZrO₂ phosphor which simultaneously emits extremely sharp as well as intense UV, violet and cyan light on exciting the host atom. The yttrium ion dopant further enhances the photoluminescence property of zirconia. These nanocrystalline phosphors are likely to have remarkable optical applications as light emitting UV-LEDs, UV lasers and multi color displays.

  6. Thermal-induced residual stresses affect the fractographic patterns of zirconia-veneer dental prostheses.

    PubMed

    Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2013-05-01

    Veneer fractures in dental zirconia-veneer prostheses are more frequent clinically than in conventional metal-ceramic systems. This is thought to be due to the increased residual stresses generated within the veneer during fabrication when zirconia is the infrastructure material. This investigation aimed to analyze the fractographic features of fractured zirconia-veneer dental crowns submitted to a load-to-failure test and to a more clinically relevant in vitro chewing simulation fatigue test. As-sintered and sandblasted zirconia copings were veneered with glass-ceramic with different coefficients of thermal expansion and cooled following two cooling rates, creating, this way, different levels of stresses within the veneer. Crowns with different thermal mismatch combinations and different cooling rates were hypothesized to present particular fracture patterns. A careful examination of >1000 scanning electron microscopy images of the fracture surfaces was conducted in search of characteristic fractographic markings of fracture mechanisms connected to the stress state of the veneer. Distinctive structural features could be observed between groups veneered with the two different glass-ceramics and between fractured crowns under static and cyclic loading. The presence/absence of residual stresses zones within the veneer have shown to play the major role in the fracture pattern of zirconia-veneer dental prostheses. For the fatigue crowns, the zirconia core was never exposed, either for sandblasted and as-sintered groups.

  7. Influence of post and core materials on distortion around 4-unit zirconia bridge margins.

    PubMed

    Inagaki, Tasuku; Komada, Wataru; Nemoto, Reina; Yoshida, Keiichi; Miura, Hiroyuki

    2014-01-01

    The purpose of this study was to evaluate the surface strain of zirconia fixed partial denture frameworks and their abutment roots when restored with two types of post and core materials. Artificial mandibular first premolars and second molars were used as the abutment teeth. Posts and cores were of two types: resin composite with glass fiber posts (RC) and cast platinum gold alloy (MC). The cores and 4-unit zirconia frameworks were bonded to the specimens. Static loading was applied to the occlusal surfaces, and the surface strain of the frameworks and roots (distal premolar and mesial molar) was measured by strain gauge method. Premolar root showed a significantly higher magnitude of principal strain than molar root. RC showed a significantly higher magnitude of principal strain than MC. The results suggest that MC restrain the surface strain compared to RC when the missing teeth are replaced by a 4-unit zirconia framework.

  8. Specific surface area determinations on intact drillcores and evaluation of extrapolation methods for rock matrix surfaces.

    PubMed

    André, M; Malmström, M E; Neretnieks, I

    2009-11-03

    Permanent storage of spent nuclear fuel in crystalline bedrock is investigated in several countries. For this storage scenario, the host rock is the third and final barrier for radionuclide migration. Sorption reactions in the crystalline rock matrix have strong retardative effects on the transport of radionuclides. To assess the barrier properties of the host rock it is important to have sorption data representative of the undisturbed host rock conditions. Sorption data is in the majority of reported cases determined using crushed rock. Crushing has been shown to increase a rock samples sorption capacity by creating additional surfaces. There are several problems with such an extrapolation. In studies where this problem is addressed, simple models relating the specific surface area to the particle size are used to extrapolate experimental data to a value representative of the host rock conditions. In this article, we report and compare surface area data of five size fractions of crushed granite and of 100 mm long drillcores as determined by the Brunauer Emmet Teller (BET)-method using N(2)-gas. Special sample holders that could hold large specimen were developed for the BET measurements. Surface area data on rock samples as large as the drillcore has not previously been published. An analysis of this data show that the extrapolated value for intact rock obtained from measurements on crushed material was larger than the determined specific surface area of the drillcores, in some cases with more than 1000%. Our results show that the use of data from crushed material and current models to extrapolate specific surface areas for host rock conditions can lead to over estimation interpretations of sorption ability. The shortcomings of the extrapolation model are discussed and possible explanations for the deviation from experimental data are proposed.

  9. Urban areas impact on surface water quality during rainfall events

    NASA Astrophysics Data System (ADS)

    Ferreira, C. S. S.; Soares, D.; Ferreira, A. J. D.; Costa, M. L.; Steenhuis, T. S.; Coelho, C. O. A.; Walsh, R. P. D.

    2012-04-01

    Increasing population and welfare puts water management under stress, especially in what concerns water quality. Surface water properties are strongly linked with hydrological processes and are affected by stream flow variability. Changes in some chemical substances concentrations can be ascribed to different water sources. Runoff generated in urban areas is considered the main responsible for water quality degradation inside catchments. This poster presents the methodology and first results of a study that is being developed to assess the impact of urbanization on surface water quality, during rainfall events. It focuses on the Ribeira dos Covões catchment (620 ha) located in central Portugal. Due to its proximity to the Coimbra city in central region, the urban areas sprawled during the last decades. In 2008, urban areas represented 32% of the area. Recently a highway was constructed crossing the catchment and a technological industrial park is being build-up in the headwaters. Several water samples were collected at four different locations: the catchment outlet and in three sub-catchments with distinct urbanization patterns - Espírito Santo that represents a highly urbanized area (45%) located over sandstone, Porto do Bordalo with 30% of urbanized area located over limestone, and IParque, mainly forest and just downstream the disturbed technological industrial park construction area. The samples were collected at different times during rainfall events to monitor the variability along the hydrograph. Six monitoring campaigns were performed: two in April 2011, at the end of the winter period, and the others between October and November 2011, after the dry summer. The number of samples collected per monitoring campaign is variable according with rainfall pattern. Parameters such as pH, conductivity, turbidity and total suspended sediments were immediately analyzed. The samples were then preserved, after filtered (0.45µm), and later analyzed for dissolved

  10. Small-area thorium features on the lunar surface

    NASA Astrophysics Data System (ADS)

    Lawrence, D. J.; Elphic, R. C.; Feldman, W. C.; Prettyman, T. H.; Gasnault, O.; Maurice, S.

    2003-09-01

    Using an improved understanding of the Lunar Prospector Gamma-Ray Spectrometer (LP-GRS) spatial footprint, we have derived a new map of global thorium abundances on the lunar surface. This map has a full-width, half-maximum spatial resolution of ~(80 km)2 and is mapped on the lunar surface using 0.5° × 0.5° pixels. This map has allowed the identification and classification of 42 small-area (<[80 km]2) thorium features across the lunar surface. Twenty of these features, all of which are located in the nearside Procellarum KREEP terrane, show a thorium-iron anticorrelation that is indicative of mixing between mare basalts and thorium-rich mafic impact-melt breccias (MIB). However, there exists at least one example of a farside location (Dewar crater) that appears to have abundances similar to the thorium-rich MIBs. This new map has also allowed the identification of mare basalts having high thorium abundances (>3 μg/g) in southwestern Mare Tranquillitatis, near the Apollo 11 landing site. With our better understanding of the LP-GRS spatial footprint, we have been able to constrain the surface thorium abundance at the Compton/Belkovich thorium anomaly to 40-55 μg/g, which is higher than any other measured location on the lunar surface and higher than most samples. Finally, using 1 km/pixel FeO abundances from Clementine and LP-GRS spatial footprint information, we have been able to obtain plausible thorium distributions around Kepler crater at a resolution of 1 km/pixel. The materials around Kepler crater appear to be a relatively simple mixing of thorium-rich MIB compositions and high-thorium mare basalts.

  11. Zirconia in fixed prosthesis. A literature review

    PubMed Central

    Román-Rodríguez, Juan L.; Ferreiroa, Alberto; Solá-Ruíz, María F.; Fons-Font, Antonio

    2014-01-01

    Statement of problem: Evidence is limited on the efficacy of zirconia-based fixed dental prostheses. Objective: To carry out a literature review of the behavior of zirconium oxide dental restorations. Material and Methods: This literature review searched the Pubmed, Scopus, Medline and Cochrane Library databases using key search words “zirconium oxide,” “zirconia,” “non-metal restorations,” “ceramic oxides,” “veneering ceramic,” “zirconia-based fixed dental prostheses”. Both in vivo and in vitro studies into zirconia-based prosthodontic restoration behavior were included. Results: Clinical studies have revealed a high rate of fracture for porcelain-veneered zirconia-based restorations that varies between 6% and 15% over a 3- to 5-year period, while for ceramo-metallic restorations the fracture rate ranges between 4 and 10% over ten years. These results provoke uncertainty as to the long-term prognosis for this material in the oral medium. The cause of veneering porcelain fractures is unknown but hypothetically they could be associated with bond failure between the veneer material and the zirconia sub-structure. Key words:Veneering ceramic, zirconia-based ceramic restoration, crown, zirconia, tooth-supported fixed prosthesis. PMID:24596638

  12. Nitridation under ammonia of high surface area vanadium aerogels

    SciTech Connect

    Merdrignac-Conanec, Odile . E-mail: odile.merdrignac@univ-rennes1.fr; El Badraoui, Khadija; L'Haridon, Paul

    2005-01-15

    Vanadium pentoxide gels have been obtained from decavanadic acid prepared by ion exchange on a resin from ammonium metavanadate solution. The progressive removal of water by solvent exchange in supercritical conditions led to the formation of high surface area V{sub 2}O{sub 5}, 1.6H{sub 2}O aerogels. Heat treatment under ammonia has been performed on these aerogels in the 450-900 deg. C temperature range. The oxide precursors and oxynitrides have been characterized by XRD, SEM, TGA, BET. Nitridation leads to divided oxynitride powders in which the fibrous structure of the aerogel is maintained. The use of both very low heating rates and high surface area aerogel precursors allows a higher rate and a lower threshold of nitridation than those reported in previous works. By adjusting the nitridation temperature, it has been possible to prepare oxynitrides with various nitrogen enrichment and vanadium valency states. Whatever the V(O,N) composition, the oxidation of the oxynitrides in air starts between 250 and 300 deg. C. This determines their potential use as chemical gas sensors at a maximum working temperature of 250 deg. C.

  13. High surface area, low weight composite nickel fiber electrodes

    NASA Technical Reports Server (NTRS)

    Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

    1993-01-01

    The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

  14. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area

    PubMed Central

    Sotiriou, Georgios A.; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E.

    2013-01-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution. PMID:23730198

  15. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area.

    PubMed

    Sotiriou, Georgios A; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E

    2011-06-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution.

  16. High Surface Area Conducting Polymer Composites for Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Gutowska, Anna; Tarasevich, Barbara; Shin, Yongsoon; Ferris, Kim; Linehan, John; White, James

    2004-03-01

    We are investigating high surface area mesoporous conducting polymer composites as new materials for on-board hydrogen storage. A recent study reported significant levels of hydrogen storage in two conducting polymers, polyaniline (PANI) and polypyrrole (PPy) (8 wtPANI).1 We have used templated synthesis methods to obtain PPy and PANI composites with mesoporous structure. We have designed composites that offer a combination of several desirable properties: - favorable wt. - multiple mechanisms of hydrogen storage (physi-, chemi-sorption, and voids available for gas compression), and high surface area meoporous morphology for enhanced gas-material interactions and greater control of gas transport. Our experimental approaches to materials design were supported by computational methods aimed at developing predictive capabilities for the structure-property relationship (SPR) of electronic structure effects on hydrogen storage capacity in conducting polymers. Computational methods were also used to support design of mesoporous structures for optimized gas-material interactions and effective diffusion control of gas transport. 1. Cho, J. J.; Song, K. S.; Kim, J. W.; Kim, T. H.; Choo, K. Fuel Chemistry Div. Reprints 2002, 47, 790.

  17. High surface area graphene foams by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Drieschner, Simon; Weber, Michael; Wohlketzetter, Jörg; Vieten, Josua; Makrygiannis, Evangelos; Blaschke, Benno M.; Morandi, Vittorio; Colombo, Luigi; Bonaccorso, Francesco; Garrido, Jose A.

    2016-12-01

    Three-dimensional (3D) graphene-based structures combine the unique physical properties of graphene with the opportunity to get high electrochemically available surface area per unit of geometric surface area. Several preparation techniques have been reported to fabricate 3D graphene-based macroscopic structures for energy storage applications such as supercapacitors. Although reaserch has been focused so far on achieving either high specific capacitance or high volumetric capacitance, much less attention has been dedicated to obtain high specific and high volumetric capacitance simultaneously. Here, we present a facile technique to fabricate graphene foams (GF) of high crystal quality with tunable pore size grown by chemical vapor deposition. We exploited porous sacrificial templates prepared by sintering nickel and copper metal powders. Tuning the particle size of the metal powders and the growth temperature allow fine control of the resulting pore size of the 3D graphene-based structures smaller than 1 μm. The as-produced 3D graphene structures provide a high volumetric electric double layer capacitance (165 mF cm-3). High specific capacitance (100 Fg-1) is obtained by lowering the number of layers down to single layer graphene. Furthermore, the small pore size increases the stability of these GFs in contrast to the ones that have been grown so far on commercial metal foams. Electrodes based on the as-prepared GFs can be a boost for the development of supercapacitors, where both low volume and mass are required.

  18. Characterization and bioactive properties of zirconia based polymeric hybrid for orthopedic applications.

    PubMed

    Thomas, Nathan P; Tran, Nhiem; Tran, Phong A; Walters, Jerry L; Jarrell, John D; Hayda, Roman A; Born, Christopher T

    2014-02-01

    Zirconia is a transition metal oxide with current applications to orthopedic implants. It has been shown to up-regulate specific genes involved in bio-integration and injury repair. This study examines the effects of zirconia and polydimethylsiloxane (PDMS) hybrids on the proliferation and viability of human primary osteoblast and fibroblast cells. In this study, zirconia-PDMS hybrid coatings were synthesized using a modified sol gel process. The hybrid material was characterized using optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle analysis. This study demonstrates that Zr-PMDS surface materials display hydrophobic surface properties coupled with a preferential deposition of polymer near the surface. Primary osteoblast and fibroblast proliferation and viability on hybrid coated surfaces were evaluated via a rapid screening methodology using WST-1 and calcein AM assays. The cells were seed at 5,000 cells per well in 96-well plates coated with various composition of Zr-PDMS hybrids. The results showed increasing cell proliferation with increasing zirconia concentration, which peaked at 90 % v/v zirconia. Proliferation of osteoblasts and fibroblasts displayed similar trends on the hybrid material, although osteoblasts displayed a bi-phasic dose response by the calcein AM assay. The results of this current study show that Zr-PDMS may be used to influence tissue-implant integration, supporting the use of the hybrid as a promising coating for orthopedic trauma implants.

  19. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

    PubMed Central

    Lameira, Deborah Pacheco; Silva, Wilkens Aurélio Buarque e; Silva, Frederico Andrade e; De Souza, Grace M.

    2015-01-01

    The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength. PMID:26576423

  20. Investigation of Sea Surface Temperature (SST) anomalies over Cyprus area

    NASA Astrophysics Data System (ADS)

    Georgiou, Andreas; Akçit, Nuhcan

    2016-08-01

    The temperature of the sea surface has been identified as an important parameter of the natural environment, governing processes that occur in the upper ocean. This paper focuses on the analysis of the Sea Surface Temperature (SST) anomalies at the greater area of Cyprus. For that, SST data derived from MODerate-resolution Imaging Spectroradiometer (MODIS) instrument on board both Aqua and Terra sun synchronous satellites were used. A four year period was chosen as a first approach to address and describe this phenomenon. Geographical Information Systems (GIS) has been used as an integrated platform of analysis and presentation in addition of the support of MATLAB®. The methodology consists of five steps: (i) Collection of MODIS SST imagery, (ii) Development of the digital geo-database; (iii) Model and run the methodology in GIS as a script; (iv) Calculation of SST anomalies; and (v) Visualization of the results. The SST anomaly values have presented a symmetric distribution over the study area with an increase trend through the years of analysis. The calculated monthly and annual average SST anomalies (ASST) make more obvious this trend, with negative and positive SST changes to be distributed over the study area. In terms of seasons, the same increase trend presented during spring, summer, autumn and winter with 2013 to be the year with maximum ASST observed values. Innovative aspects comprise of straightforward integration and modeling of available tools, providing a versatile platform of analysis and semi-automation of the operation. In addition, the fine resolution maps that extracted from the analysis with a wide spatial coverage, allows the detail representation of SST and ASST respectively in the region.

  1. Surface States and Effective Surface Area on Photoluminescent P-Type Porous Silicon

    NASA Technical Reports Server (NTRS)

    Weisz, S. Z.; Porras, A. Ramirez; Resto, O.; Goldstein, Y.; Many, A.; Savir, E.

    1997-01-01

    The present study is motivated by the possibility of utilizing porous silicon for spectral sensors. Pulse measurements on the porous-Si/electrolyte system are employed to determine the surface effective area and the surface-state density at various stages of the anodization process used to produce the porous material. Such measurements were combined with studies of the photoluminescence spectra. These spectra were found to shift progressively to the blue as a function of anodization time. The luminescence intensity increases initially with anodization time, reaches a maximum and then decreases with further anodization. The surface state density, on the other hand, increases with anodization time from an initial value of about 2 x 10(exp 12)/sq cm surface to about 1013 sq cm for the anodized surface. This value is attained already after -2 min anodization and upon further anodization remains fairly constant. In parallel, the effective surface area increases by a factor of 10-30. This behavior is markedly different from the one observed previously for n-type porous Si.

  2. Tuning the self-assembled monolayer formation on nanoparticle surfaces with different curvatures: Investigations on spherical silica particles and plane-crystal-shaped zirconia particles

    PubMed Central

    Feichtenschlager, Bernhard; Lomoschitz, Christoph J.; Kickelbick, Guido

    2011-01-01

    The ordering of dodecyl-chain self-assembled monolayers (SAM) on different nanoscopic surfaces was investigated by FT-IR studies. As model systems plane-crystal-shaped ZrO2 nanoparticles and spherical SiO2 nanoparticles were examined. The type of capping agent was chosen dependent on the substrate, therefore dodecylphosphonic acid and octadecylphosphonic acid were used for ZrO2 and dodecyltrimethoxysilane for SiO2 samples. The plane ZrO2 nanocrystals yielded more ordered alkyl-chain structures whereas spherical SiO2 nanoparticles showed significantly lower alkyl-chain ordering. Submicron-sized silica spheres revealed a significantly higher alkyl chain ordering, comparable to an analogously prepared SAM on a non-curved plane oxidized Si-wafer. In the case of ZrO2 nanocrystals an intense alkyl-chain alignment could be disturbed by decreasing the grafting density from the maximum of 2.1 molecules/nm2 through the variation of coupling agent concentration to lower values. Furthermore, the co-adsorption of a different coupling agent, such as phenylphosphonic acid for ZrO2 and phenyltrimethoxysilane for SiO2, resulted in a significantly lower alkyl-chain ordering for ZrO2 plane crystals and for large SiO2 spherical particles at high grafting density. An increasing amount of order-disturbing molecules leads to a gradual decrease in alkyl-chain alignment on the surface of the inorganic nanoparticles. In the case of the ZrO2 nanoparticle system it is shown via dynamic light scattering (DLS) that the mixed monolayer formation on the particle surface impacts the dispersion quality in organic solvents such as n-hexane. PMID:21549385

  3. The natural history of the growth of the hand: I. Hand area as a percentage of body surface area.

    PubMed

    Amirsheybani, H R; Crecelius, G M; Timothy, N H; Pfeiffer, M; Saggers, G C; Manders, E K

    2001-03-01

    The use of a patient's own hand as a tool to estimate the area of burn injury is well documented. The area of the palmar surface of one hand has been estimated to be 1 percent of the body surface area. The area of the palmar surface of the hand was measured to test the accuracy of this estimate and then compared with the body surface area as calculated by formulas in common use. This study also sought to determine the natural history of the growth of the hand to permit development of a readily available, bedside means of estimating hand area and body surface area. Bilateral hand tracings were obtained from 800 volunteers ranging in age from 2 to 89 years. The area of each tracing was determined using an integrating planimeter. The height and weight of each individual were measured, and his/her body surface area was calculated. The palmar hand's percentage of body surface area was determined by calculating the quotient for hand area divided by body surface area. Additionally, the width of the hand was measured from the ulnar aspect at the palmar digital crease of the small finger to the point where the thumb rested against the base of the index finger. The length of the hand was measured from the middle of the interstylon to the tip of the middle finger. These two figures were multiplied together to obtain a product which approximated the area of the hand. Based on the most commonly used DuBois formula for calculating body surface area, the area of palmar surface of the hand corresponds to 0.78 +/- 0.08 percent of the body surface area in adults. The percentage varies somewhat with age and reaches a maximum of 0.87 +/- 0.06 percent in young children. Multiplying the length of the hand by its width overestimates the area of the hand as determined by planimetry by only 2 percent. A patient's own hand may be used as a complementary, readily available template for estimation of burn area or other areas of disease or injury. In adults, the area of tracing of the outline

  4. The effect of enamel matrix derivative on spreading, proliferation, and differentiation of osteoblasts cultured on zirconia.

    PubMed

    Wada, Yoshiyuki; Mizuno, Morimichi; Nodasaka, Yoshinobu; Tamura, Masato

    2012-01-01

    This study investigated the effect of enamel matrix derivative (EMD) on spreading, proliferation, and differentiation of osteoblasts cultured on zirconia disks with smooth and rough surfaces. EMD was added to the culture medium or coated on zirconia disks that had machined (smooth) or sandblasted (rough) surfaces. The effects of EMD on cell proliferation of MC3T3-E1 osteoblastic cells were examined using a hemocytometer. Osteoblastic differentiation was examined by histologic analysis of alkaline phosphatase (ALP) activity and the degree of mineralization. ALP activity was also measured quantitatively. Scanning electron microscopic analysis was performed to observe cell morphology. Enzyme-linked immunosorbent assay of osteocalcin and reverse-transcriptase polymerase chain reaction of osteocalcin, osteopontin, and type 1 collagen were performed to investigate the expression of osteoblast-related genes. The addition of EMD to the medium enhanced the spreading, proliferation, and differentiation of osteoblasts cultured on zirconia. However, when it was coated on zirconia, EMD reduced osteoblastic spreading and adhesion in the early stage of culture, although it enhanced proliferation and differentiation of osteoblasts in later stages. A promotive effect of EMD on osteocalcin mRNA expression, mineralization, and ALP activity of osteoblasts cultured on the rough surface was observed. EMD may contribute to treatment with zirconia implants via its promotion of osteoblastic proliferation and activity. However, the procedure for application of EMD may be a crucial factor for the outcome of implants.

  5. Enhancing pilot situational awareness of the airport surface movement area

    NASA Technical Reports Server (NTRS)

    Jones, D. R.; Young, S. D.

    1994-01-01

    Two studies are being conducted to address airport surface movement area safety and capacity issues by providing enhanced situational awareness information to pilots. One study focuses on obtaining pilot opinion of the Runway Status Light System (RSLS). This system has been designed to reduce the likelihood of runway incursions by informing pilots when a runway is occupied. The second study is a flight demonstration of an rate integrated system consisting of an electronic moving map in the cockpit and display of the aircraft identification to the controller. Taxi route and hold warning information will be sent to the aircraft data link for display on the electronic moving map. This paper describes the plans for the two studies.

  6. Method for producing high surface area chromia materials for catalysis

    DOEpatents

    Gash, Alexander E.; Satcher, Joe; Tillotson, Thomas; Hrubesh, Lawrence; Simpson, Randall

    2007-05-01

    Nanostructured chromium(III)-oxide-based materials using sol-gel processing and a synthetic route for producing such materials are disclosed herein. Monolithic aerogels and xerogels having surface areas between 150 m.sup.2/g and 520 m.sup.2/g have been produced. The synthetic method employs the use of stable and inexpensive hydrated-chromium(III) inorganic salts and common solvents such as water, ethanol, methanol, 1-propanol, t-butanol, 2-ethoxy ethanol, and ethylene glycol, DMSO, and dimethyl formamide. The synthesis involves the dissolution of the metal salt in a solvent followed by an addition of a proton scavenger, such as an epoxide, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively.

  7. Sodium hydroxide catalyzed monodispersed high surface area silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhakta, Snehasis; Dixit, Chandra K.; Bist, Itti; Abdel Jalil, Karim; Suib, Steven L.; Rusling, James F.

    2016-07-01

    Understanding of the synthesis kinetics and our ability to modulate medium conditions allowed us to generate nanoparticles via an ultra-fast process. The synthesis medium is kept quite simple with tetraethyl orthosilicate (TEOS) as precursor and 50% ethanol and sodium hydroxide catalyst. Synthesis is performed under gentle conditions at 20 °C for 20 min Long synthesis time and catalyst-associated drawbacks are most crucial in silica nanoparticle synthesis. We have addressed both these bottlenecks by replacing the conventional Stober catalyst, ammonium hydroxide, with sodium hydroxide. We have reduced the overall synthesis time from 20 to 1/3 h, ∼60-fold decrease, and obtained highly monodispersed nanoparticles with 5-fold higher surface area than Stober particles. We have demonstrated that the developed NPs with ∼3-fold higher silane can be used as efficient probes for biosensor applications.

  8. Reduced cortical surface area in adolescents with conduct disorder.

    PubMed

    Sarkar, Sagari; Daly, Eileen; Feng, Yue; Ecker, Christine; Craig, Michael C; Harding, Duncan; Deeley, Quinton; Murphy, Declan G M

    2015-08-01

    Children with conduct disorder (CD) are at increased risk of developing antisocial personality disorder and psychopathy in adulthood. Neuroimaging research has identified abnormal cortical volume (CV) in CD. However, CV comprises two genetically and developmentally separable components: cortical thickness (CT) and surface area (SA). Aim of this study is to explore the relationship between the cortical constituents of CV in boys with CD. We applied FreeSurfer software to structural MRI data to derive measures of CV, CT, and SA in 21 boys with CD and 19 controls. Relationships between these cortical measures were investigated. Boys with CD had significantly reduced CV and SA compared to non-CD boys in ventromedial and dorsolateral prefrontal cortex. We found no significant between-group differences in CT. Reduced prefrontal CV in boys with CD is associated with significantly reduced SA in the same regions. This finding may help to identify specific neurodevelopmental mechanisms underlying cortical deficits observed in CD.

  9. Sodium hydroxide catalyzed monodispersed high surface area silica nanoparticles

    PubMed Central

    Bhakta, Snehasis; Dixit, Chandra K; Bist, Itti; Jalil, Karim Abdel; Suib, Steven L; Rusling, James F

    2016-01-01

    Understanding of the synthesis kinetics and our ability to modulate medium conditions allowed us to generate nanoparticles via an ultra-fast process. The synthesis medium is kept quite simple with tetraethyl orthosilicate (TEOS) as precursor and 50% ethanol and sodium hydroxide catalyst. Synthesis is performed under gentle conditions at 20 °C for 20 min Long synthesis time and catalyst-associated drawbacks are most crucial in silica nanoparticle synthesis. We have addressed both these bottlenecks by replacing the conventional Stober catalyst, ammonium hydroxide, with sodium hydroxide. We have reduced the overall synthesis time from 20 to 1/3 h, ~60-fold decrease, and obtained highly monodispersed nanoparticles with 5-fold higher surface area than Stober particles. We have demonstrated that the developed NPs with ~3-fold higher silane can be used as efficient probes for biosensor applications. PMID:27606068

  10. High surface area ThO/sub 2/ catalyst

    DOEpatents

    Colmenares, C.A.; Somorjai, G.A.; Maj, J.J.

    1983-06-21

    A ThO/sub 2/ catalyst having a high surface area of about 80 to 125m/sup 2//g is synthesized. The compound is synthesized by simultaneously mixing an aqueous solution of ThNO/sub 3/(NO/sub 3/)/sub 4/.4H/sub 2/O with an aqueous solution of Na/sub 2/CO/sub 3/.H/sub 2/O, to produce a solution and solid ThOCO/sub 3/. The solid ThOCO/sub 3/ is separated from the solution, and then calcined at a temperature of about 225 to 300/sup 0/C for about 40 to 55 hours to produce ThO/sub 2/. The ThO/sub 2/ catalyst produced includes Na present as a substitutional cation in an amount equal to about 5 to 10 at. %.

  11. Effect of cation dopants in zirconia on interfacial properties in nickel/zirconia systems: an atomistic modeling study

    NASA Astrophysics Data System (ADS)

    Iskandarov, Albert M.; Ding, Yingna; Umeno, Yoshitaka

    2017-02-01

    Cation doping is often used to stabilize the cubic or tetragonal phase of zirconia for enhanced thermomechanical and electrochemical properties. In the present paper we report a combined density functional theory (DFT) and molecular dynamics study of the effect of Sc, Y, and Ce dopants on properties of Ni/\\text{Zr}{{\\text{O}}2} interfaces and nickel sintering. First, we develop an MD model that is based on DFT data for various nickel/zirconia interfaces. Then, we employ the model to simulate Ni nanoparticles coalescing on a zirconia surface. The results show the possibility of particle migration by means of fast sliding over the surface when the work of separation is small (<1.0\\text{J} {{\\text{m}}-2} ). The sliding observed for the O-terminated Ni(1 1 1)/\\text{Zr}{{\\text{O}}2} (1 1 1) interface is not affected by dopants in zirconia because the work of separation of the doped interface stays small. The most pronounced effect of the dopants is observed for the Zr-terminated Ni(1 1 1)/\\text{Zr}{{\\text{O}}2} (1 1 1) interface, which possesses a large work of separation (4.4\\text{J} {{\\text{m}}-2} ) and thus restricts the sliding mechanism of Ni nanoparticle migration. DFT calculations for the interface revealed that dopants with a smaller covalent radius result in a larger energy barriers for Ni diffusion. We analyze this effect and discuss how it can be used to suppress nickel sintering by using the dopant selection.

  12. Inlay-retained zirconia fixed dental prosthesis: clinical and laboratory procedures.

    PubMed

    Monaco, Carlo; Cardelli, Paolo; Bolognesi, Michele; Scotti, Roberto; Ozcan, Mutlu

    2012-01-01

    Many treatment options are currently available for single tooth replacement, such as metal-ceramic, all-ceramic, direct or indirect fiber-reinforced composite fixed dental prostheses (FDPs) or implants. Inlay-retained FDPs could be indicated especially when adjacent teeth have preexisting restorations and where implant placement is not possible or not indicated. In such cases, indication of both metal-ceramic and fiber-reinforced composite FDPs has certain disadvantages. This paper describes the use of all-ceramic inlay-retained FDPs with zirconia frameworks, veneered with a press-on technique. The retainer margins were made of pressed ceramic to make adhesive luting possible. In deep cavities, a full contour press-on ceramic all around the retainers increased the available surface area for the adhesive approach.

  13. Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia

    PubMed Central

    Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

    2016-01-01

    Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were −583.892 (NaOH), −569.048 [Ca(OH)2], −547.393 (MgO), and −530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic. PMID:27785013

  14. Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia.

    PubMed

    Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

    Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were -583.892 (NaOH), -569.048 [Ca(OH)2], -547.393 (MgO), and -530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic.

  15. Fitting accuracy and fracture resistance of crowns using a hybrid zirconia frame made of both porous and dense zirconia.

    PubMed

    Nakamura, Takashi; Sugano, Tsuyoshi; Usami, Hirofumi; Wakabayashi, Kazumichi; Ohnishi, Hiroshi; Sekino, Tohru; Yatani, Hirofumi

    2015-01-01

    The purpose of this study is to evaluate the fitting accuracy and fracture resistance of crowns using a hybrid zirconia frame made of both porous and dense zirconia. Commercial semi-sintered zirconia, sintered dense zirconia and sintered hybrid zirconia were used. Sintered zirconia was milled using the CAD/CAM system, and semi-sintered zirconia was milled and sintered to fabricate molar crown frames. Completed frames were veneered with tooth-colored porcelain. The marginal and internal gaps between frames/crowns and abutments were measured. Each crown specimen was subjected to a fracture test. There were no significant differences in marginal and internal gap among all the frames and crowns. The crown with the hybrid zirconia frame had a 31-35% greater fracture load than that with the commercial or dense zirconia frame (p<0.01). This suggests that the all-ceramic crowns with a hybrid zirconia frame have a high fracture resistance.

  16. Grinding model and material removal mechanism of medical nanometer zirconia ceramics.

    PubMed

    Zhang, Dongkun; Li, Changhe; Jia, Dongzhou; Wang, Sheng; Li, Runze; Qi, Xiaoxiao

    2014-01-01

    Many patents have been devoted to developing medical nanometer zirconia ceramic grinding techniques that can significantly improve both workpiece surface integrity and grinding quality. Among these patents is a process for preparing ceramic dental implants with a surface for improving osseo-integration by sand abrasive finishing under a jet pressure of 1.5 bar to 8.0 bar and with a grain size of 30 µm to 250 µm. Compared with other materials, nano-zirconia ceramics exhibit unmatched biomedical performance and excellent mechanical properties as medical bone tissue and dentures. The removal mechanism of nano-zirconia materials includes brittle fracture and plastic removal. Brittle fracture involves crack formation, extension, peeling, and chipping to completely remove debris. Plastic removal is similar to chip formation in metal grinding, including rubbing, ploughing, and the formation of grinding debris. The materials are removed in shearing and chipping. During brittle fracture, the grinding-led transverse and radial extension of cracks further generate local peeling of blocks of the material. In material peeling and removal, the mechanical strength and surface quality of the workpiece are also greatly reduced because of crack extension. When grinding occurs in the plastic region, plastic removal is performed, and surface grinding does not generate grinding fissures and surface fracture, producing clinically satisfactory grinding quality. With certain grinding conditions, medical nanometer zirconia ceramics can be removed through plastic flow in ductile regime. In this study, we analyzed the critical conditions for the transfer of brittle and plastic removal in nano-zirconia ceramic grinding as well as the high-quality surface grinding of medical nanometer zirconia ceramics by ELID grinding.

  17. Surface ozone in the urban area of Manaus, Amazonas, Brazil

    NASA Astrophysics Data System (ADS)

    Souza, R. A. F. D.; Costa, P. S.; Silva, C.; Godoi, R. M.; Martin, S. T.; Tota, J.; Barbosa, H. M.; Pauliquevis, T.; Ferreira De Brito, J.; Artaxo, P.; Manzi, A. O.; Wolf, S. A.; Cirino, G. G.

    2014-12-01

    When nitrogen oxides from vehicle and industrial emissions mix with volatile organic compounds from trees and plants with exposure to sunlight, a chemical reaction occurs contributing to ground-level ozone pollution. The preliminary results of the surface ozone study in urban area of Manaus, Amazonas State, Brazil, are presented for the first intensive operating period (IOP1) of the GoAmazon experiment (February/March 2014). Photochemical ozone production was found to be a regular process, with an afternoon maximum of the ozone mixing ratio of lower than 20 ppbv for cloudy days or clear sky weather. Typical ozone concentrations at mid-day were low (about 10 ppb). On the other hand, several high-value ozone episodes with surface ozone mixing ratios up to three times larger were registered during the dry season of 2013 (September/October). At the beginning of the wet season, the ozone concentration in Manaus decreased significantly, but diurnal variations can be found during the days with rainfall and other fast changes of meteorological conditions. Possible explanations of the nature of pulsations are discussed. Photochemical ozone production by local urban plumes of Manaus is named as a first possible source of the ozone concentration and biomass burning or power plant emissions are suggested as an alternative or an additional source.

  18. Observations of Nuclear Explosive Melt Glass Textures and Surface Areas

    SciTech Connect

    Kersting, A B; Smith, D K

    2006-01-17

    This memo report summarizes our current knowledge of the appearance of melt glass formed and subsequently deposited in the subsurface after an underground nuclear test. We have collected archived pictures and melt glass samples from a variety of underground nuclear tests that were conducted at the Nevada Test Site (NTS) during the U.S. nuclear testing program. The purpose of our work is to better determine the actual variation in texture and surface area of the melt glass material. This study is motivated by our need to better determine the rate at which the radionuclides incorporated in the melt glass are released into the subsurface under saturated and partially saturated conditions. The rate at which radionuclides are released from the glass is controlled by the dissolution rate of the glass. Glass dissolution, in turn, is a strong function of surface area, glass composition, water temperature and water chemistry (Bourcier, 1994). This work feeds into an ongoing experimental effort to measure the change in surface area of analog glasses as a function of dissolution rate. The conclusions drawn from this study help bound the variation in the textures of analog glass samples needed for the experimental studies. The experimental work is a collaboration between Desert Research Institute (DRI) and Earth and Environmental Sciences-Lawrence Livermore National Laboratory (EES-LLNL). On March 4, 1999 we hosted a meeting at LLNL to present and discuss our findings. The names of the attendees appear at the end of this memo. This memo report further serves to outline and summarize the conclusions drawn from our meeting. The United States detonated over 800 underground nuclear tests at the NTS between 1951 and 1992. In an effort to evaluate the performance of the nuclear tests, drill-back operations were carried out to retrieve samples of rock in the vicinity of the nuclear test. Drill-back samples were sent to Los Alamos National Laboratory (LANL) and Lawrence Livermore

  19. Surface-based morphometry reveals distinct cortical thickness and surface area profiles in Williams syndrome.

    PubMed

    Green, Tamar; Fierro, Kyle C; Raman, Mira M; Saggar, Manish; Sheau, Kristen E; Reiss, Allan L

    2016-04-01

    Morphometric investigations of brain volumes in Williams syndrome (WS) consistently show significant reductions in gray matter volume compared to controls. Cortical thickness (CT) and surface area (SA) are two constituent parts of cortical gray matter volume that are considered genetically distinguishable features of brain morphology. Yet, little is known about the independent contribution of cortical CT and SA to these volumetric differences in WS. Thus, our objectives were: (i) to evaluate whether the microdeletion in chromosome 7 associated with WS has a distinct effect on CT and SA, and (ii) to evaluate age-related variations in CT and SA within WS. We compared CT and SA values in 44 individuals with WS to 49 age- and sex-matched typically developing controls. Between-group differences in CT and SA were evaluated across two age groups: young (age range 6.6-18.9 years), and adults (age range 20.2-51.5 years). Overall, we found contrasting effects of WS on cortical thickness (increases) and surface area (decreases). With respect to brain topography, the between-group pattern of CT differences showed a scattered pattern while the between-group surface area pattern was widely distributed throughout the brain. In the adult subgroup, we observed a cluster of increases in cortical thickness in WS across the brain that was not observed in the young subgroup. Our findings suggest that extensive early reductions in surface area are the driving force for the overall reduction in brain volume in WS. The age-related cortical thickness findings might reflect delayed or even arrested development of specific brain regions in WS. © 2016 Wiley Periodicals, Inc.

  20. Microscopic surface tension down to molecular dimensions and microthermodynamic surface areas of molecules or clusters

    NASA Astrophysics Data System (ADS)

    Sinanoǧlu, Oktay

    1981-07-01

    Surface tension, surface energy, and entropy of small droplets, n clusters, and of cavities in liquids for sizes down to a single molecule are obtained. Rigourous relations are derived that relate microsurface properties to the usual handbook properties of bulk liquids. The microvalues and their dependence on the ratio of the cluster, droplet, or cavity size to the average liquid molecular size are given for common solvents, polar and nonpolar, including alcohols, water, hydrocarbons, rare gas liquids, and liquid (or solid) metals. Microscopic values are less than bulk-planar values by around 40% for nonpolar liquids, and greater for polar liquids by around 60%. The n-cluster (or cavity) sizes ? at which the microsurface properties approach the bulk values within a desired percentage, e.g., 5%, are given. The ordinary, bulk thermodynamic properties of liquids are also related to new useful quantities: ''microthermodynamic surface areas'' of molecules from which, using the equations given, ''experimental'' geometric (van der Waals) surface areas of molecules are calculated. The molecular surface properties introduced in the theory of ''solvophobic forces'' by this author earlier are finding applications presently in areas like HPLC (''high pressure liquid chromatogrphy''), multicomponent adsorption from solution phase (e.g., purification of waters from trace carcinogens), large ion association, protein structure, and drug-biopolymer binding, as well as the earlier ones for the prediction of rates and equilibria in diverse solvents in physical organic chemistry. The microsurface properties given now apply also to the convex case, e.g., the n clusters in nucleation and in metal cluster phenomena.

  1. The impact of built-up surfaces on land surface temperatures in Italian urban areas.

    PubMed

    Morabito, Marco; Crisci, Alfonso; Messeri, Alessandro; Orlandini, Simone; Raschi, Antonio; Maracchi, Giampiero; Munafò, Michele

    2016-05-01

    Urban areas are characterized by the very high degree of soil sealing and continuous built-up areas: Italy is one of the European countries with the highest artificial land cover rate, which causes a substantial spatial variation in the land surface temperature (LST), modifying the urban microclimate and contributing to the urban heat island effect. Nevertheless, quantitative data regarding the contribution of different densities of built-up surfaces in determining urban spatial LST changes is currently lacking in Italy. This study, which aimed to provide clear and quantitative city-specific information on annual and seasonal spatial LST modifications resulting from increased urban built-up coverage, was conducted generally throughout the whole year, and specifically in two different periods (cool/cold and warm/hot periods). Four cities (Milan, Rome, Bologna and Florence) were included in the study. The LST layer and the built-up-surface indicator were obtained via use of MODIS remote sensing data products (1km) and a very high-resolution map (5m) of built-up surfaces recently developed by the Italian National Institute for Environmental Protection and Research. The relationships between the dependent (mean daily, daytime and nighttime LST values) and independent (built-up surfaces) variables were investigated through linear regression analyses, and comprehensive built-up-surface-related LST maps were also developed. Statistically significant linear relationships (p<0.001) between built-up surfaces and spatial LST variations were observed in all the cities studied, with a higher impact during the warm/hot period than in the cool/cold ones. Daytime and nighttime LST slope patterns depend on the city size and relative urban morphology. If implemented in the existing city plan, the urban maps of built-up-surface-related LST developed in this study might be able to support more sustainable urban land management practices by identifying the critical areas (Hot

  2. Lung deposited surface area size distributions of particulate matter in different urban areas

    NASA Astrophysics Data System (ADS)

    Kuuluvainen, Heino; Rönkkö, Topi; Järvinen, Anssi; Saari, Sampo; Karjalainen, Panu; Lähde, Tero; Pirjola, Liisa; Niemi, Jarkko V.; Hillamo, Risto; Keskinen, Jorma

    2016-07-01

    Lung deposited surface area (LDSA) concentration is considered as a relevant metric for the negative health effects of aerosol particles. We report for the first time the size distributions of the LDSA measured in urban air. The measurements were carried out in the metropolitan area of Helsinki, including mobile laboratory and stationary measurements in different outdoor environments, such as traffic sites, a park area, the city center and residential areas. The main instrument in this study was an electrical low pressure impactor (ELPI), which was calibrated in the field to measure the LDSA concentration. The calibration factor was determined to be 60 μm2/(cm3 pA). In the experiments, the LDSA size distributions were found to form two modes at the traffic sites and in the city center. Both of these traffic related particle modes, the nucleation mode and the soot mode, had a clear contribution to the total LDSA concentration. The average total concentrations varied from 12 to 94 μm2/cm3, measured in the park area and at the traffic site next to a major road, respectively. The LDSA concentration was found to correlate with the mass of fine particles (PM2.5), but the relation of these two metrics varied between different environments, emphasizing the influence of traffic on the LDSA. The results of this study provide valuable information on the total concentrations and size distributions of the LDSA for epidemiological studies. The size distributions are especially important in estimating the contribution of outdoor concentrations on the concentrations inside buildings and vehicles through size-dependent penetration factors.

  3. Assessment of dialyzer surface in online hemodiafiltration; objective choice of dialyzer surface area.

    PubMed

    Maduell, Francisco; Ojeda, Raquel; Arias-Guillén, Marta; Bazan, Giannina; Vera, Manel; Fontseré, Néstor; Massó, Elisabeth; Gómez, Miquel; Rodas, Lida; Jiménez-Hernández, Mario; Piñeiro, Gastón; Rico, Nayra

    2015-01-01

    Online hemodiafiltration (OL-HDF) is currently the most effective technique. Several randomized studies and meta-analyses have observed a reduction in mortality as well as a direct association with convective volume. Currently, it has not been well established whether a larger dialyzer surface area could provide better results in terms of convective and depurative effectiveness. The aim of this study was to assess the effect of larger dialyzer surface areas on convective volume and filtration capacity. A total of 37 patients were studied, including 31 men and 6 women, who were in the OL-HDF program using a 5008 Cordiax monitor with auto-substitution. Each patient was analyzed in 3 sessions in which only the dialyzer surface area varied (1.0, 1.4 or 1.8 m(2)). The concentrations of urea (60 Da), creatinine (113 Da), β2-microglobulin (11800 Da), myoglobin (17200 Da) and α1-microglobulin (33000 Da) were determined in serum at the beginning and end of each session in order to calculate the percent reduction of these solutes. The convective volume reached was 29.8 ± 3.0 with 1.0 m(2), 32.7 ± 3.1 (an increase of 6%) with 1.4 m(2), and 34.7 ± 3.3 L (an increase of 16%) with 1.8 m(2) (p<.001). The increased surface of the dialyzer showed an increase in the dialysis dose as well as urea and creatinine filtration. The percentage of β2m reduction increased from 80.0 ± 5.6 with 1.0 m(2) to 83.2 ± 4.2 with 1.4 m(2) and to 84.3 ± 4.0% with 1.8 m(2). As for myoglobin and a1-microglobulin, significant differences were observed between smaller surface area (1.0 m(2)) 65.6 ± 11 and 20.1 ± 9.3 and the other two surface areas, which were 70.0 ± 8.1 and 24.1 ± 7.1 (1.4 m(2)) and 72.3 ± 8.7 and 28.6 ± 12 (1.8 m(2)). The 40% and 80% increases in surface area led to increased convective volumes of 6 and 16% respectively, while showing minimal differences in both the convective volume as well as the filtration capacity when the CUF was higher than 45 ml/h/mmHg. It is

  4. Effects of excluded surface area and adsorbate clustering on surface adsorption of proteins. II. Kinetic models.

    PubMed Central

    Minton, A P

    2001-01-01

    Models for equilibrium surface adsorption of proteins have been recently proposed (Minton, A. P., 2000. Biophys. Chem. 86:239-247) in which negative cooperativity due to area exclusion by adsorbate molecules is compensated to a variable extent by the formation of a heterogeneous population of monolayer surface clusters of adsorbed protein molecules. In the present work this concept is extended to treat the kinetics of protein adsorption. It is postulated that clusters may grow via two distinct kinetic pathways. The first pathway is the diffusion of adsorbed monomer to the edge of a preexisting cluster and subsequent accretion. The second pathway consists of direct deposition of a monomer in solution onto the upper (solution-facing) surface of a preexisting cluster ("piggyback" deposition) and subsequent incorporation into the cluster. Results of calculations of the time course of adsorption, carried out for two different limiting models of cluster structure and energetics, show that in the absence of piggyback deposition, enhancement of the tendency of adsorbate to cluster can reduce, but not eliminate, the negative kinetic cooperativity due to surface area exclusion by adsorbate. Apparently noncooperative (Langmuir-like) and positively cooperative adsorption progress curves, qualitatively similar to those reported in several published experimental studies, require a significant fraction of total adsorption flux through the piggyback deposition pathway. According to the model developed here and in the above-mentioned reference, the formation of surface clusters should be a common concomitant of non-site-specific surface adsorption of proteins, and may provide an important mechanism for assembly of organized "protein machines" in vivo. PMID:11259279

  5. The effect of silica-coating by sol-gel process on resin-zirconia bonding.

    PubMed

    Lung, Christie Ying Kei; Kukk, Edwin; Matinlinna, Jukka Pekka

    2013-01-01

    The effect of silica-coating by sol-gel process on the bond strength of resin composite to zirconia was evaluated and compared against the sandblasting method. Four groups of zirconia samples were silica-coated by sol-gel process under varied reagent ratios of ethanol, water, ammonia and tetraethyl orthosilicate and for different deposition times. One control group of zirconia samples were treated with sandblasting. Within each of these five groups, one subgroup of samples was kept in dry storage while another subgroup was aged by thermocycling for 6,000 times. Besides shear bond testing, the surface topography and surface elemental composition of silica-coated zirconia samples were also examined using scanning electron microscopy and X-ray photoelectron spectroscopy. Comparison of silica coating methods revealed significant differences in bond strength among the Dry groups (p<0.001) and Thermocycled groups (p<0.001). Comparison of sol-gel deposition times also revealed significant differences in bond strength among the Dry groups (p<0.01) and Thermocycled groups (p<0.001). Highest bond strengths were obtained after 141-h deposition: Dry (7.97±3.72 MPa); Thermocycled (2.33±0.79 MPa). It was concluded that silica-coating of zirconia by sol-gel process resulted in weaker resin bonding than by sandblasting.

  6. Evaluation of zirconia-porcelain interface using X-ray diffraction.

    PubMed

    Alghazzawi, Tariq F; Janowski, Gregg M

    2015-09-14

    The aim of this study was to determine if accelerated aging of porcelain veneering had an effect on the surface properties specific to a tetragonal-to-monoclinic transformation (TMT) of zirconia restorations. Thirty-six zirconia samples were milled and sintered to simulate core fabrication followed by exposure to various combinations of surface treatments including as-received (control), hydrofluoric acid (HF), application of liner plus firings, application of porcelain by manual layering and pressing with firing, plus accelerated aging. The quantity of transformed tetragonal to monoclinic phases was analyzed utilized an X-ray diffractometer and one-way analysis of variance was used to analyze data. The control samples as provided from the dental laboratory after milling and sintering process had no TMT (Xm = 0). There was an effect on zirconia samples of HF application with TMT (Xm = 0.8%) and liner plus HF application with TMT (Xm = 8.7%). There was an effect of aging on zirconia samples (no veneering) with significant TMT (Xm = 70.25%). Both manual and pressing techniques of porcelain applications reduced the TMT (manual, Xm = 4.41%, pressing, Xm = 11.57%), although there was no statistical difference between them. It can be concluded that simulated applications of porcelain demonstrated the ability to protect zirconia from TMT after aging with no effect of a liner between different porcelain applications. The HF treatment also caused TMT.

  7. Biomechanical three-dimensional finite element analysis of monolithic zirconia crown with different cement type

    PubMed Central

    2015-01-01

    PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimensional finite element models. Four models were prepared according to different cement types (zinc phosphate, polycarboxylate, glass ionomer, and resin). A load of 700 N was applied vertically on the crowns (8 loading points). Maximum principal stress was determined. RESULTS Zinc phosphate cement had a greater stress concentration in the cement layer, while polycarboxylate cement had a greater stress concentration on the distal surface of the monolithic zirconia crown and abutment tooth. Resin cement and glass ionomer cement showed similar patterns, but resin cement showed a lower stress distribution on the lingual and mesial surface of the cement layer. CONCLUSION The test results indicate that the use of different luting agents that have various elastic moduli has an impact on the stress distribution of the monolithic zirconia crowns, cement layers, and abutment tooth. Resin cement is recommended for the luting agent of the monolithic zirconia crowns. PMID:26816578

  8. Directional solidification of the alumina-zirconia ceramic eutectic system

    SciTech Connect

    Boldt, Christopher

    1994-07-27

    It is possible to produce alumina-zirconia ceramic samples through existing solidification techniques. The resulting microstructures typically consist of rods of zirconia in an alumina matrix, although a lamellar structure has been noted in some cases. In nearly all cases, colony growth was present which may possibly result from grain size, repeated nucleation events, and lamellar oscillations. In the same vein, it appears that the amount of impurities within the system might be the underlying cause for the colony growth. Colony growth was diminished through impurity control as the higher purity samples exhibited colony free behavior. In addition to colony formations, faceted alumina dendrites or nonfaceted zirconia dendrites may result in the ceramic if the sample is solidified out of the coupled zone. In all cases, for larger-sized Bridgman samples, a lower limit in the eutectic spacing was noted. The solidification model which includes the kinetic effect has been developed, although the effect appears to be negligible under present experimental conditions. A spacing limit might also occur due to the result of heat flow problems. Heat flow out of the ceramic is difficult to control, often causing radial and not axial growth. This behavior is exaggerated in the presence of impurities. Thus, higher purity powders should always be used. Higher purity samples, in addition to yielding a more microstructurally uniform ceramic, also showed increased directionality. In the future, the kinetic model needs to be examined in more detail, and further research needs to be accomplished in the area<