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Sample records for alumina inlay failure

  1. High failure rate of the Duraloc Constrained Inlay

    Science.gov (United States)

    2009-01-01

    Background and purpose After total hip arthroplasty, dislocations are a frequent complication and are difficult to treat in some patients. A great variety of implants and antiluxation mechanisms are used in surgical therapy. Methods 8 patients had 9 Duraloc Constrained Inlays implanted at our clinic between October 2003 and November 2006, for recurrent dislocations. A retrospective follow-up study was carried out. Results All patients suffered a failure of the expanding ring, the metal ring being squeezed out of the polyethylene notch. The mechanism of failure can be explained by impingement due to the implant design. At the time of writing, 3 patients have had to undergo revision surgery. Interpretation The Duraloc Constrained Inlay has shown unacceptably high failure rates. PMID:19916686

  2. Influence of preparation design on failure risks of ceramic inlays: a finite element analysis.

    Science.gov (United States)

    Ona, Masahiro; Watanabe, Chie; Igarashi, Yoshimasa; Wakabayashi, Noriyuki

    2011-08-01

    To assess the influence of preparation design on failure risk of ceramic inlays by means of finite element (FE) analysis. Both 2D and 3D models of the maxillary first premolar were constructed. MOD ceramic inlays were designed with an isthmus width of 1.5 to 5.0 mm and a minimum thickness of 1 to 3 mm. Occlusal contact motion and debonding at the tooth/ceramic adhesive interface were simulated in 2D models by downward displacement of a ceramic ball (1.5 mm in diameter) onto the central groove. The stress distributions within the inlays and at the interface were analyzed using 3D models. A maximum occlusal load of 250 N was assumed. The maximum principal stress at the base of the inlays was constant among models of different isthmus widths, although it decreased considerably as inlay thickness increased from 1 mm to 2 mm. The maximum shear stress at the adhesive interface increased as the width of the inlay decreased and the distance between the occlusal contact and the margin decreased to 0.3 mm or less. The maximum principal stress on the occlusal surface was relatively low and insensitive to inlay design; however, it was increased by a simulated adhesive failure. The failure risk at the base of the inlay is minimized by increasing the minimum inlay thickness. As the occlusal contact becomes close to the margin, the adhesive failure risk is increased, potentially leading to an increase in risk of fracture on the occlusal surface.

  3. Failure of Polyethylene Inlays in Cementless Total Hip Arthroplasty: A Retrieval Analysis

    Science.gov (United States)

    Lee, Christoph; Heisel, Christian; Thomsen, Marc; Bitsch, Rudi G.

    2016-01-01

    A retrieval analysis has been performed on 50 polyethylene inlays of cementless screw ring implants (Mecring, Mecron, Berlin, Germany) to investigate the failure mechanism of this specific open cup hip arthroplasty design that has shown a high clinical failure rate. Design-specific damage modes like rim creep, collar fatigue, and backside wear were assessed. Furthermore, the inlays were measured using a CMM to determine deformation. In 90% backside wear was observed and collar fatigue occurred in 68% of the cases. Rim creep was present in 38% of the polyethylene inlays. In 90% of the cases the cup opening diameter was 32.1 mm or less and 46% had a diameter less than 32 mm. It seems that creep and deformation of the polyethylene leads to a reduced diameter at the cup opening and consequently decreased clearance. To avoid this type of failure, polyethylene inlays should be supported at the back by the cup to reduce the risk of ongoing creep deformation. PMID:27660758

  4. Marginal adaptation, fracture load and macroscopic failure mode of adhesively luted PMMA-based CAD/CAM inlays.

    Science.gov (United States)

    Ender, Andreas; Bienz, Stefan; Mörmann, Werner; Mehl, Albert; Attin, Thomas; Stawarczyk, Bogna

    2016-02-01

    To evaluate marginal adaptation, fracture load and failure types of CAD/CAM polymeric inlays. Standardized prepared human molars (48) were divided into four groups (n=12): (A) PCG (positive control group); adhesively luted glass-ceramic inlays, (B) TRX; CAD/CAM polymeric inlays luted using a self-adhesive resin cement, (C) TAC; CAD/CAM polymeric inlays luted using a conventional resin cement, and (D) NCG (negative control group); direct-filled resin-based composite restorations. All specimens were subjected to a chewing simulator. Before and after chewing fatigue, marginal adaptation was assessed at two interfaces: (1) between dental hard tissues and luting cement and (2) between luting cement and restoration. Thereafter, the specimens were loaded and the fracture loads, as well as the failure types, were determined. The data were analysed using three- and one-way ANOVA with post hoc Scheffé test, two sample Student's t-test (pinlays showed similar marginal adaptation and fracture load values compared to adhesively luted glass-ceramic inlays. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Inlay-retained cantilever fixed dental prostheses to substitute a single premolar: impact of zirconia framework design after dynamic loading.

    Science.gov (United States)

    Shahin, Ramez; Tannous, Fahed; Kern, Matthias

    2014-08-01

    The purpose of this in-vitro study was to evaluate the influence of the framework design on the durability of inlay-retained cantilever fixed dental prostheses (IR-FDPs), made from zirconia ceramic, after artificial ageing. Forty-eight caries-free human premolars were prepared as abutments for all-ceramic cantilevered IR-FDPs using six framework designs: occlusal-distal (OD) inlay, OD inlay with an oral retainer wing, OD inlay with two retainer wings, mesial-occlusal-distal (MOD) inlay, MOD inlay with an oral retainer ring, and veneer partial coping with a distal box (VB). Zirconia IR-FDPs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The bonding surfaces were air-abraded (50 μm alumina/0.1 MPa), and the frameworks were bonded with adhesive resin cement. Specimens were stored for 150 d in a 37°C water bath during which they were thermocycled between 5 and 55°C for 37,500 cycles; thereafter, they were exposed to 600,000 cycles of dynamic loading with a 5-kg load in a chewing simulator. All surviving specimens were loaded onto the pontic and tested until failure using a universal testing machine. The mean failure load of the groups ranged from 260.8 to 746.7 N. Statistical analysis showed that both MOD groups exhibited significantly higher failure loads compared with the other groups (i.e. the three OD groups and the VB group) and that there was no significant difference in the failure load among the OD groups and the VB group. In conclusion, zirconia IR-FDPs with a modified design exhibited promising failure modes. © 2014 Eur J Oral Sci.

  6. Probability of failure of veneered glass fiber-reinforced composites and glass-infiltrated alumina with or without zirconia reinforcement.

    Science.gov (United States)

    Chong, Kok-Heng; Chai, John

    2003-01-01

    The probability of failure under flexural load of veneered specimens of a unidirectional glass fiber-reinforced composite (FibreKor/Sculpture), a bidirectional glass fiber-reinforced composite (Vectris/Targis), a glass-infiltrated alumina (In-Ceram Alumina/Vita alpha), and a zirconia-reinforced glass-infiltrated alumina (In-Ceram Zirconia/Vita alpha) was investigated; a metal-ceramic (PG200/Vita omega) system served as a control. Ten uniform beams of the veneered core materials were fabricated for each system and subjected to a three-point bending test. The data were analyzed using the Weibull method. The failure load of specimens at a 10% probability of failure (B10 load) was compared. The mode of failure was analyzed. The B10 load of the systems investigated was not significantly different from that of the metal-ceramic system. FibreKor possessed significantly higher B10 load than Vectris, In-Ceram Alumina, and In-Ceram Zirconia. The B10 strength loads of Vectris, In-Ceram Alumina, and In-Ceram Zirconia were not significantly different from one another. The probability of FibreKor to fracture under a flexural load was significantly lower than that of Vectris, In-Ceram Alumina, or In-Ceram Zirconia.

  7. Considerations for ceramic inlays in posterior teeth: a review

    Science.gov (United States)

    Hopp, Christa D; Land, Martin F

    2013-01-01

    This review of ceramic inlays in posterior teeth includes a review of the history of ceramic restorations, followed by common indications and contraindications for their use. A discussion on the potential for tooth wear is followed by a review of recommended preparation design considerations, fabrication methods, and material choices. Despite the improved materials available for fabrication of porcelain inlays, fracture remains a primary mode of inlay failure. Therefore, a brief discussion on strengthening methods for ceramics is included. The review concludes with a section on luting considerations, and offers the clinician specific recommendations for luting procedures. In conclusion, inlay success rates and longevity, as reported in the literature, are summarized. PMID:23750101

  8. Composite inlays: a systematic review.

    Science.gov (United States)

    Grivas, E; Roudsari, R V; Satterthwaite, J D

    2014-09-01

    The purpose of this study is to review the available literature related to composite inlays. Electronic databases published up to November 2013 were searched. Studies that evaluate composite resin inlays for the restoration of posterior teeth were selected. The studies should compare composite inlays against gold inlays, ceramic inlays and direct composite fillings regarding longevity, aesthetic quality and postoperative sensitivity or comparing the clinical effectiveness of them on premolars versus molars or on 1-2 surface preparations versus multi-surface preparations. Despite the heterogeneity of the available clinical trials composite inlays seem to be an effective method for the restoration of posterior teeth.

  9. A retrospective clinical study on the longevity of posterior Class II cast gold inlays/onlays.

    Science.gov (United States)

    Mulic, A; Svendsen, G; Kopperud, S E

    2018-03-01

    To investigate the longevity and reasons for failure of posterior cast Class II gold inlays and onlays among a group of Norwegian adults. The term inlay was used for both inlays and onlays. A cohort of 138 patients regularly attending a general practice for check-up were examined in 2016. The patients had a total of 391 posterior gold inlays placed in the period 1970-2015. The inlays were categorized as successful, repaired or failed. Reasons for failure were classified as either "secondary caries", "fractures", "lost inlay" or "other". Participation was voluntary and no compensation was given. The mean age of the patients at placement was 50.8 years (SD: 12.7 yr). Most gold inlays were placed in molars (85.9%) and 14.1% in premolars; 49.4% of the inlays were in the maxilla and the 50.6% in the mandibula. Average length of follow-up was 11.6 years (range: 1-46 years, SD: 7.9); 82.9% were classified as successful, 10.7% as repaired and 6.4% as failed. Reasons for failure were secondary caries (41.3%), lost inlay (25.4%), fractures (23.8%) and other (9.5%). Mean annual failure rate (AFR) was 1.69% for repaired and failed inlays combined. However, if repaired inlays were considered as success, the AFR decreased to 0.57%. Multi-level Cox regression analyses identified low age of the patient and high number of restored surfaces as risk factors for failure. The present retrospective clinical study demonstrated an acceptable annual failure rate for Class II cast gold inlays. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Three-dimensional finite element analysis of stress distribution in inlay-restored mandibular first molar under simultaneous thermomechanical loads.

    Science.gov (United States)

    Çelik Köycü, Berrak; Imirzalioğlu, Pervin; Özden, Utku Ahmet

    2016-01-01

    Functional occlusal loads and intraoral temperature changes create stress in teeth. The purpose of this study was to evaluate the impact of simultaneous thermomechanical loads on stress distribution related to inlay restored teeth by three-dimensional finite element analysis. A mandibular first molar was constructed with tooth structures, surrounding bone and inlays of Type II gold alloy, ceramic, and composite resin. Stress patterns on the restorative materials, adhesive resin, enamel and dentin were analyzed after simulated temperature changes from 36°C to 4 or 60°C for 2 s with 200-N oblique loading. The results showed that the three types of inlays had similar stress distribution in the tooth structures and restorative materials. Concerning the adhesive resin, the composite resin inlay model exhibited lower stresses than ceramic and gold alloy inlays. Simultaneous thermomechanical loads caused high stress patterns in inlay-restored teeth. Composite resin inlays may be the better choice to avoid adhesive failure.

  11. [Ceramic inlays and onlays].

    Science.gov (United States)

    van Pelt, A W; de Kloet, H J; van der Kuy, P

    1996-11-01

    Large direct composite restorations can induce shrinkage related postoperative sensitivity. Indirect resin-bonded (tooth colored) restorations may perhaps prevent these complaints. Indirect bonded ceramics are especially attractive because of their biocompatibility and esthetic performance. Several procedures and techniques are currently available for the fabrication of ceramic restorations: firing, casting, heat-pressing and milling. In this article the different systems are described. Advantages, disadvantages and clinical performance of ceramic inlays are compared and discussed.

  12. Alumina-on-alumina total hip replacement for femoral neck fracture in healthy patients

    Directory of Open Access Journals (Sweden)

    Moretti Lorenzo

    2011-02-01

    Full Text Available Abstract Background Total hip replacement is considered the best option for treatment of displaced intracapsular fractures of the femoral neck (FFN. The size of the femoral head is an important factor that influences the outcome of a total hip arthroplasty (THA: implants with a 28 mm femoral head are more prone to dislocate than implants with a 32 mm head. Obviously, a large head coupled to a polyethylene inlay can lead to more wear, osteolysis and failure of the implant. Ceramic induces less friction and minimal wear even with larger heads. Methods A total of 35 THAs were performed for displaced intracapsular FFN, using a 32 mm alumina-alumina coupling. Results At a mean follow-up of 80 months, 33 have been clinically and radiologically reviewed. None of the implants needed revision for any reason, none of the cups were considered to have failed, no dislocations nor breakage of the ceramic components were recorded. One anatomic cementless stem was radiologically loose. Conclusions On the basis of our experience, we suggest that ceramic-on-ceramic coupling offers minimal friction and wear even with large heads.

  13. Effect of resin cements and aging on cuspal deflection and fracture resistance of teeth restored with composite resin inlays.

    Science.gov (United States)

    Salaverry, Aurélio; Borges, Gilberto Antonio; Mota, Eduardo Gonçalves; Burnett Júnior, Luiz Henrique; Spohr, Ana Maria

    2013-12-01

    To evaluate the influence of resin cements and aging on cuspal deflection, fracture resistance, and mode of failure of endodontically treated teeth restored with composite resin inlays. Seventy-two maxillary premolars were divided into 6 groups: 1: sound teeth as control (C); 2: preparations without restoration (WR); 3: inlays luted with RelyX ARC (ARC); 4: inlays luted with RelyX Unicem (RLXU); 5: inlays luted with Maxcem Elite (MCE); 6: inlays luted with SeT (ST). Groups 2 to 6 received mesio-occlusal-distal preparations and endodontic treatment. Stone casts were made for groups 3 to 6. Composite resin inlays were built over each cast and luted with the resin cements. A 200-N load was applied on the occlusal aspect and the cuspal deflection was measured using a micrometer before and after 500,000 cycles of fatigue loading (200 N; 500,000 cycles). The specimens were then submitted to an axial load until failure. The median cuspal deflection (µm) and median fracture resistance (N) were calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (p inlays luted with RelyX ARC maintained cuspal deflection stability and showed higher fracture resistance of the teeth than did inlays luted with the other cements tested.

  14. Dedicated composite fillings − inlays

    Directory of Open Access Journals (Sweden)

    Šaulić Slobodan

    2003-01-01

    Full Text Available Background. The aim of the study was to evaluate the quality and persistance of esthetics of dedicated inlay by clinical methods. Methods. The paper reviews the clinical significance and technique of preparing particular composite inlays before and after the construction of the metallic framework partial denture. On the basis of indications the total of 30 inlays were placed into cavities under relatively dry working conditions. Six, twelve eighteen and twenty-four months after the placement of filling, control check-up was carried out by Ryge criteria. Results. After two years marginal discoloration as well as the change of the colour occured in 3.3% of inlays. There was neither detectable secondary caries, nor the symtoms of pulpal damage. The requirements to be fulfilled concerning the composite materials in order that they can be implemented for this purpose, were also discussed. Conclusion. From the clinical point of view, purpouse inlays from Herculite XRV lab C8B in combination with Opti Bond System and composite cement Porcelite Dual Cure showed high functional and esthetic values in the observational period of two years.

  15. Cutting inlays with a laser

    Science.gov (United States)

    Swaczyna, Irena; Grabczewski, Zbigniew

    1995-03-01

    To cut inlay from a stack of glued veneer a CO2 HEBAR-1A laser was used. For setting optimal working parameters of the set used in industrial production of inlay the following elements were defined: the shape and dimensions of the cutting fissure, the dependence between the width of the cutting fissure and the speed with which the laser beam moves and the total thickness of the stack of veneer sheets, the application of the laser for cutting various patterns. Computer aided designing and computer steering of the laser beam enables fast and precise production of large numbers of inlay elements not only from wood but also from other materials like glass, stone, metal, etc. Taking into consideration the high running cost of such a laser set and its very big production only few factories or even one factory in the given area could produce inlay ready for gluing. Further investigation should be carried out on this field particularly considering the lowering of costs not only in inlay production but generally where cutting of wood is concerned.

  16. A prospective clinical study of ceromer inlays: results up to 53 months.

    Science.gov (United States)

    Kükrer, Derya; Gemalmaz, Deniz; Kuybulu, Emre Orhon; Bozkurt, Funda Oztürk

    2004-01-01

    The aim of this study was to evaluate the clinical performance of a ceromer (Targis) in indirect inlay restorations. Ninty-nine Targis inlays (37 premolars, 62 molars) were placed in 51 patients (mean age 27 years). Twenty-nine percent of the restorations were placed in patients with parafunctional habits such as bruxism or clenching. All restorations were in occlusion and were placed using Variolink (43 Variolink Ultra, 56 Variolink II high viscosity) in combination with the Syntac Classic adhesive system under rubber dam isolation. The restorations were evaluated according to modified USPHS criteria at baseline and for a recall period of 6 to 53 months after insertion. There were two clinically unacceptable failures in total. Fracture was registered in one molar at 38 months, and one molar needed endodontic treatment 7 months after insertion. Based on Kaplan-Meier statistical analysis, the estimated survival rate of the inlays was 97.9% (97.7% for Variolink Ultra, 98.2% for Variolink II high viscosity). It was apparent that deterioration occurred in the surface texture of the inlays, since a slightly pitted surface was observed in 29% of the inlays at recall examinations. In this in vivo study, Targis inlays luted with both resin luting agents functioned satisfactorily, with a relatively low fracture rate over a mean evaluation period of 28 months.

  17. Clinical evaluation of prefabricated ceramic inlays

    Directory of Open Access Journals (Sweden)

    H Murali

    2016-01-01

    Full Text Available Background: One of the methods to overcome the problem of polymerization contraction of posterior composites is to use prefabricated ceramic inlays in combination with composites. Several studies have shown that these pre fabricated ceramic inlays act as mega fillers which allow a reduction in resin based composite volume by 50-75% and a concomitant reduction in polymerization shrinkage and marginal micro leakage. Moreover the integration of pre fabricated ceramic inlays into composites reduces the overall coefficient of thermal expansion. Aims and Objectives: The performance of cerena prefabricated inlay system was evaluated. Material and Methods: 20 proximo occlusal cavities were restored with cerana prefabricated inlay system in patients. The performance of cerena pre fabricated inlay system in the oral cavity was recorded at base line follow up using Modified USPHS Ryge criteria at the end of 3, 6, and 12 months. Results: The alpha and Bravo values for the anatomic form, marginal integrity and caries assessment was evaluated. Alpha values were ideal. The Cerena pre- fabricated inlay system showed good fracture resistance, good marginal integrity and maintenance of antomic forms at end of 12 months period. Conclusion: The cerena pre-fabricated inlay system is a good treatment modality and provides a good restorative material at the end of 12 months too.

  18. Bonding values of two contemporary ceramic inlay materials to dentin following simulated aging.

    Science.gov (United States)

    Khalil, Ashraf Abdelfattah; Abdelaziz, Khalid Mohamed

    2015-12-01

    To compare the push-out bond strength of feldspar and zirconia-based ceramic inlays bonded to dentin with different resin cements following simulated aging. Occlusal cavities in 80 extracted molars were restored in 2 groups (n=40) with CAD/CAM feldspar (Vitablocs Trilux forte) (FP) and zirconia-based (Ceramill Zi) (ZR) ceramic inlays. The fabricated inlays were luted in 2 subgroups (n=20) with either etch-and-bond (RelyX Ultimate Clicker) (EB) or self-adhesive (RelyX Unicem Aplicap) (SA) resin cement. Ten inlays in each subgroup were subjected to 3,500 thermal cycles and 24,000 loading cycles, while the other 10 served as control. Horizontal 3 mm thick specimens were cut out of the restored teeth for push out bond strength testing. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's comparisons at α=.05. The mode of ceramic-cement-dentin bond failure for each specimen was also assessed. No statistically significant differences were noticed between FP and ZR bond strength to dentin in all subgroups (ANOVA, P=.05113). No differences were noticed between EB and SA (Tukey's, P>.05) bonded to either type of ceramics. Both adhesive and mixed modes of bond failure were dominant for non-aged inlays. Simulated aging had no significant effect on bond strength values (Tukey's, P>.05) of all ceramic-cement combinations although the adhesive mode of bond failure became more common (60-80%) in aged inlays. The suggested cement-ceramic combinations offer comparable bonding performance to dentin substrate either before or after simulated aging that seems to have no adverse effect on the achieved bond.

  19. Clinical study of indirect composite resin inlays in posterior stress-bearing preparations placed by dental students: results after 6 months and 1, 2, and 3 years.

    Science.gov (United States)

    Manhart, Juergen; Chen, Hong-Yan; Mehl, Albert; Hickel, Reinhard

    2010-05-01

    This longitudinal randomized controlled clinical trial evaluated composite resin inlays for clinical acceptability in single- or multisurface preparations and provides a survey of the results up to 3 years. Twenty-one dental students placed 75 Artglass (Heraeus Kulzer) and 80 Charisma (Heraeus Kulzer) composite resin inlays in Class 1 and 2 preparations in posterior teeth (89 adults). Clinical evaluation was performed at baseline and up to 3 years by two other dentists using modified USPHS criteria. A total of 89.8% of Artglass and 84.1% of Charisma inlays were assessed as clinically excellent or acceptable with predominating Alfa scores. Up to the 3-year recall, five Artglass and 10 Charisma inlays failed mainly because of postoperative symptoms, bulk fracture, and loss of marginal integrity. No significant differences between composite resin materials could be detected at 3 years for all clinical criteria (P > .05). The comparison of restoration performance with time within both groups yielded a significant increase in marginal discoloration (P inlay systems. However, both changes were mainly effects of scoring shifts from Alfa to Bravo. No significant differences (P > .05) were recorded comparing premolars and molars. Small inlays showed significantly better outcome for some of the tested clinical parameters (P inlays exhibited an annual failure rate of 3.4% and 5.3% that is within the range of published data. Indirect composite inlays are a competitive restorative procedure in stress-bearing preparations.

  20. A practice-based research network on the survival of ceramic inlay/onlay restorations

    NARCIS (Netherlands)

    Collares, K.; Correa, M.B.; Laske, M.; Kramer, E.; Reiss, B.; Moraes, R.R.; Huysmans, M.C.; Opdam, N.J.

    2016-01-01

    OBJECTIVE: To evaluate prospectively the longevity of ceramic inlay/onlay restorations placed in a web-based practice-based research network and to investigate risk factors associated with restoration failures. MATERIALS AND METHODS: Data were collected by a practice-based research network called

  1. Ceramic inlays: is the inlay thickness an important factor influencing the fracture risk?

    Science.gov (United States)

    Holberg, Christof; Rudzki-Janson, Ingrid; Wichelhaus, Andrea; Winterhalder, Philipp

    2013-07-01

    It is still unclear whether the inlay thickness is an important factor influencing the fracture risk of ceramic inlays. As high tensile stresses increase the fracture risk of ceramic inlays, the objective of the present finite element method (FEM) study was to biomechanically analyze the correlation between inlay thickness (T) and the induced first principal stress. Fourteen ceramic inlay models with varying thickness (0.7-2.0 mm) were generated. All inlays were combined with a CAD model of a first mandibular molar (tooth 46), including the PDL and a mandibular segment which was created by means of the CT data of an anatomical specimen. Two materials were defined for the ceramic inlays (e.max(®) or empress(®)) and an occlusal force of 100 N was applied. The first principal stress was measured within each inlay and the peak values were considered and statistically analyzed. The stress medians ranged from 20.7 to 22.1 MPa in e.max(®) and from 27.6 to 29.2 MPa in empress(®) inlays. A relevant correlation between the first principal stress and thickness (T) could not be detected, neither for e.max(®) (Spearman: r=0.028, p=0.001), nor for empress(®) (Spearman: r=0.010, p=0.221). In contrast, a very significant difference (pinlay materials (M) was verified. Under the conditions of the present FEM study, the inlay thickness does not seem to be an important factor influencing the fracture risk of ceramic inlays. However, further studies are necessary to confirm this. Published by Elsevier Ltd.

  2. Fatigue resistance and crack propensity of large MOD composite resin restorations: direct versus CAD/CAM inlays.

    Science.gov (United States)

    Batalha-Silva, Silvana; de Andrada, Mauro Amaral Caldeira; Maia, Hamilton Pires; Magne, Pascal

    2013-03-01

    To assess the influence of material/technique selection (direct vs. CAD/CAM inlays) for large MOD composite adhesive restorations and its effect on the crack propensity and in vitro accelerated fatigue resistance. A standardized MOD slot-type tooth preparation was applied to 32 extracted maxillary molars (5mm depth and 5mm bucco-palatal width) including immediately sealed dentin for the inlay group. Fifteen teeth were restored with direct composite resin restoration (Miris2) and 17 teeth received milled inlays using Paradigm MZ100 block in the CEREC machine. All inlays were adhesively luted with a light curing composite resin (Filtek Z100). Enamel shrinkage-induced cracks were tracked with photography and transillumination. Cyclic isometric chewing (5 Hz) was simulated, starting with a load of 200 N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200 and 1400 N at a maximum of 30,000 cycles each. Samples were loaded until fracture or to a maximum of 185,000 cycles. Teeth restored with the direct technique fractured at an average load of 1213 N and two of them withstood all loading cycles (survival=13%); with inlays, the survival rate was 100%. Most failures with Miris2 occurred above the CEJ and were re-restorable (67%), but generated more shrinkage-induced cracks (47% of the specimen vs. 7% for inlays). CAD/CAM MZ100 inlays increased the accelerated fatigue resistance and decreased the crack propensity of large MOD restorations when compared to direct restorations. While both restorative techniques yielded excellent fatigue results at physiological masticatory loads, CAD/CAM inlays seem more indicated for high-load patients. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Eight-year outcome of posterior inlay-retained all-ceramic fixed dental prostheses.

    Science.gov (United States)

    Harder, S; Wolfart, S; Eschbach, S; Kern, M

    2010-11-01

    The main goal of this prospective clinical study was to evaluate the outcome of inlay-retained fixed dental prostheses (FDPs) made from heat-pressed lithium-disilicate glass-ceramic. Forty-five FDPs were placed in 42 patients (21 women, mean age 36.1 years and 21 men, mean age 42.0 years). The FDPs replaced 4 premolars and 19 molars in the maxilla and 4 premolars and 18 molars in the mandible. Preparations were performed in accordance with general principles for ceramic inlay restorations. Five of the 45 FDPs were hybrid-retained restorations, i.e. one abutment tooth with an inlay retainer and one with a full crown retainer. All FDPs were pressed in one piece using lithium-disilicate ceramic (IPS e.max Press, Ivoclar Vivadent). The minimum dimensions for the proximal connector were 4mm in height and 4mm in width (16 mm(2)) with a minimum occlusal ceramic thickness of 1.5mm. The surfaces of the inlay retainer were conditioned by etching with hydrofluoric acid 5% and silane application. Standard adhesive luting techniques were performed using a dentin adhesive (Syntac Classic, Ivoclar Vivadent) and a resin composite (Variolink II, Ivoclar Vivadent). Clinical follow-up examinations were performed annually. The mean observation periods were 70 months (minimum 4, maximum 123 months). Twenty-seven FDPs (60%) failed during the observation period and had to be replaced. The Kaplan-Meier survival rate for inlay-retained FDPs was 57% after 5 years and 38% after 8 years, while for hybrid-retained FDPs it was 100% after 5 and 60% after 8 years. Inlay-retained FDPs made from lithium-disilicate ceramic present a high clinical failure rate and therefore cannot be recommended. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Inlays made from a hybrid material: adaptation and bond strengths.

    Science.gov (United States)

    Bottino, M A; Campos, F; Ramos, N C; Rippe, M P; Valandro, L F; Melo, R M

    2015-01-01

    The aim of this study was to evaluate the internal fit, marginal adaptation, and bond strengths of inlays made of computer-aided design/computer-aided manufacturing feldspathic ceramic and polymer-infiltrated ceramic. Twenty molars were randomly selected and prepared to receive inlays that were milled from both materials. Before cementation, internal fit was achieved using the replica technique by molding the internal surface with addition silicone and measuring the cement thicknesses of the pulpal and axial walls. Marginal adaptation was measured on the occlusal and proximal margins of the replica. The inlays were then cemented using resin cement (Panavia F2.0) and subjected to two million thermomechanical cycles in water (200 N load and 3.8-Hz frequency). The restored teeth were then cut into beams, using a lathe, for microtensile testing. The contact angles, marginal integrity, and surface patterns after etching were also observed. Statistical analysis was performed using two-way repeated measures analysis of variance (p<0.05), the Tukey test for internal fit and marginal adaptation, and the Student t-test for bond strength. The failure types (adhesive or cohesive) were classified on each fractured beam. The results showed that the misfit of the pulpal walls (p=0.0002) and the marginal adaptation (p=0.0001) of the feldspathic ceramic were significantly higher when compared to those of the polymer-infiltrated ceramic, while the bond strength values of the former were higher when compared to those of the latter. The contact angle of the polymer-infiltrated ceramic was also higher. In the present study, the hybrid ceramic presented improved internal and marginal adaptation, but the bond strengths were higher for the feldspathic ceramic.

  5. Comparison of the operation of arthroscopic tibial inlay and traditional tibial inlay for posterior cruciate ligament reconstruction

    OpenAIRE

    Lu, Daifeng; Xiao, Mochao; Lian, Yongyun; Zhou, Yong; Liu, Xuefeng

    2014-01-01

    Objective: To perform dual-bundle reconstruction of posterior cruciate ligament using full arthroscopic tibial inlay technology with self-designed tibia tunnel drilling system and to compare the effect of arthroscopic tibial inlay versus traditional technique for posterior cruciate ligament reconstruction. Material and methods: 32 patients were randomly divided into experiment group (improved tibial inlay, n = 17) and control group (traditional tibial inlay, n = 15). Self-designed tibia tunne...

  6. Clinical study of indirect composite resin inlays in posterior stress-bearing cavities placed by dental students: results after 4 years.

    Science.gov (United States)

    Huth, Karin Christine; Chen, Hong Yan; Mehl, Albert; Hickel, Reinhard; Manhart, Juergen

    2011-07-01

    This longitudinal randomized controlled clinical trial evaluated the longevity of composite resin inlays in single- or multi-surface cavities up to 4 years. 21 dental students placed 75 Artglass and 80 Charisma composite resin inlays in class I and II cavities in posterior teeth (89 adult patients) luted with dual-curing resin cements. Clinical evaluation was performed up to 4 years using modified USPHS criteria. 87.2% of Artglass and 76.6% of Charisma inlays were assessed to be clinically excellent or acceptable. Up to the 4-year recall 5 Artglass and 11 Charisma inlays failed mainly because of postoperative symptoms, bulk fracture, and loss of marginal integrity. No significant differences between both composite resin materials could be detected at 4 years for all clinical criteria (Mann-Whitney U-test, p>0.05). The comparison of restoration performance with time yielded a significant increase in marginal discolouration and postoperative symptoms (pinlay systems. However, the changes were mainly effects of scoring shifts from alfa to bravo. Small inlays compared to large inlays and premolar restorations compared to molar restorations showed significant better outcome for some of the tested clinical parameters for the Artglass inlays (pinlays no such influences were revealed. Clinical assessment of Artglass and Charisma composite resin inlays exhibited an annual failure rate of 3.2% and 5.9% that is within the range of published data. Within the limitations of this study indirect composite inlays are a competitive restorative procedure in stress-bearing preparations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Up to 27-years clinical long-term results of chairside Cerec 1 CAD/CAM inlays and onlays.

    Science.gov (United States)

    Otto, Tobias

    The objective of this follow-up study was to examine the performance of Cerec 1 inlays and onlays in terms of clinical quality over a mean functional period of 25 years. Out of 200 Cerec 1 inlays and onlays placed consecutively in 108 patients in a private practice between 1989 and early 1991, 141 restorations could be reevaluated in 65 patients after up to 26 years and 10 months. All ceramic inlays and onlays had been generated chairside using the Cerec 1 method, and had been seated adhesively using bonding composite. At follow-up examinations, the restorations were classified based on modified United States Public Health Service (USPHS) criteria. According to the Kaplan-Meier analysis, the success rate of Cerec 1 inlays and onlays dropped to 87.5% after up to 27 years. In 19 patients, a total of 23 failures were found. Of these failures, 78% were caused by either ceramic fractures (65%) or tooth fractures (13%). The reasons for the remaining failures were caries (18%), and endodontic problems (4%). Three-surface restorations had a significantly higher failure risk (P < 0.05) than one-, two-, and four-surface restorations, and restorations in premolars presented a lower failure risk than those in molars. The survival probability of 87.5% after up to 27 years of clinical service of Cerec 1 computer-assisted design/computer-assisted manufacturing (CAD/CAM) restorations made of Vita Mark I feldspathic ceramic proved to be highly acceptable in private practice.

  8. Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay

    Directory of Open Access Journals (Sweden)

    Shizuma Shibata

    2014-06-01

    Full Text Available The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n = 10: G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p > 0.05. All specimens withstood the fatigue protocol (185,000 cycles, representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.

  9. Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay.

    Science.gov (United States)

    Shibata, Shizuma; Gondo, Renata; Araújo, Élito; Mello Roesler, Carlos Rodrigo de; Baratieri, Luiz Narciso

    2014-01-01

    The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n=10): G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p>0.05). All specimens withstood the fatigue protocol (185,000 cycles), representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.

  10. Inlay butterfly miringoplasty. Our experience.

    Science.gov (United States)

    Cruz Toro, Paula; Callejo Castillo, Ángela; Moya Martínez, Rafael; Juan, Iván Domenech

    Multiple surgical techniques have been proposed to close tympanic perforations. Eavey, two decades ago, described a technique aimed at closing central perforations in children. For this, he designed a butterfly-shaped cartilage graft that was placed between the tympanic membrane in an inlay manner. This technique showed great effectiveness for the closure of perforations as well as low morbidity, rapidity and great economic difference. We performed a descriptive study of a series of cases analysing 32 interventions in children and adults with the modified Eavey technique, during the period from January 2012 to November 2016. We evaluated the surgical and audiometric functional results. Surgical success was achieved in 93% of cases, including complete closures in 27 patients (84%) and 3 cases in which minimal asymptomatic dehiscences occurred. There was rejection of the graft and persistence of the perforation in only one case. No major surgical or postoperative complications associated with the procedure were described. The mean improvement in the audiometric gap was from 17dB preoperatively to 7dB after the intervention. The modified Eavey technique is a low morbidity, cost-effective procedure with a technical facility that proves effective for the closure of tympanic perforations in adults and children. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. All rights reserved.

  11. Comparison of fracture resistance of teeth restored with ceramic inlay and resin composite: an in vitro study.

    Science.gov (United States)

    Desai, Priti D; Das, Utapal Kumar

    2011-01-01

    The aim of this study was to evaluate the in vitro fracture resistance of teeth restored with bonded ceramic inlay and direct composite resin restoration in comparison to the normal tooth. This study evaluated the fracture strength of the teeth restored with bonded ceramic inlay and direct composite resin restoration in comparison to the normal teeth. Thirty intact human maxillary first premolars were assigned to three groups: Group 1 - comprising sound/unprepared teeth (control). Group 2 - comprising of Class-II direct composite resin restored teeth and Group 3 - comprising Class-II ceramic inlay restored teeth. Cavities were prepared with occlusal width of 1/3 intercuspal distance and 2 mm deep pulpally. Group 2 teeth were restored with hybrid composite resin (Z350 3M ESPE, USA) and group 3 teeth were restored with Vitadur Alpha alumina (Ivoclare Vivadent, Liechtenstein, Europe). Ceramic inlay was bonded with adhesive cement (rely X resin cement of 3MESPE, USA). The specimens were subjected to a compressive load until they fractured. Data were analyzed statistically by unpaired Student's t test. The fracture resistant strength, expressed as kilonewton (KN), was group 1 - 1.51 KN, group 2 - 1.25 KN, and group 3 - 1.58 KN. Statistically, group III had highest fracture resistance followed by group I, while group II had the lowest average fracture resistance. The fracture resistant strength of teeth restored with ceramic inlay was comparable to that of the normal intact teeth or slightly higher, while teeth restored with direct composite resin restoration showed less fracture resistant strength than that of the normal teeth.

  12. The all-ceramic, inlay supported fixed partial denture. Part 2. Fixed partial denture design: a finite element analysis.

    Science.gov (United States)

    Thompson, M C; Field, C J; Swain, M V

    2011-09-01

    The clinical use of all-ceramic crowns and fixed partial dentures has seen widespread adoption over the past few years due to their increasing durability and longevity. However, the application of inlays as an abutment design has not been as readily embraced because of their relatively high failure rates. With the use of an idealized inlay preparation design and prosthesis form which better distributes the tensile stresses, it is possible to utilize the inlay as support for an all-ceramic fixed partial denture. Utilizing a three-dimensional finite element analysis, a direct comparison of the inlay supported all-ceramic bridge against the traditional full crown supported all-ceramic bridge is made. The results demonstrate that peak stresses in the inlay bridge are around 20% higher than in the full crown supported bridge with von Mises peaking at about 730 MPa when subjected to theoretical average maximum bite force in the molar region of 700 N, which is similar to the ultimate tensile strengths of current zirconia based ceramics. © 2011 Australian Dental Association.

  13. Operator vs. material influence on clinical outcome of bonded ceramic inlays.

    Science.gov (United States)

    Frankenberger, Roland; Reinelt, Christian; Petschelt, Anselm; Krämer, Norbert

    2009-08-01

    The aim of the present study was to clinically evaluate the suitability of Definite Multibond and Definite ormocer resin composite for luting of Cergogold glass ceramic inlays in a two-center trial involving two dentists. Thirty-nine patients received 98 Cergogold inlays with at least one inlay luted with Definite Multibond/Definite (n=45) and at least one inlay luted with Syntac/Variolink Ultra (n=53) in a split mouth design. Treatments were carried out in two private practices by two operators (Operator A: n=38; Operator B: n=60). Forty-four cavities required caries profunda treatment, 23 cavities exhibited no enamel at the cervical margin. At baseline (2 months), and after 6, 14, 27, and 51 months of clinical service, the restorations were investigated according to modified USPHS criteria. The drop-out rate was 3% after 4 years. After 48 months of clinical service, 21 restorations in 16 patients (9 luted with Definite, 12 with Variolink; 2 placed by operator A and 19 by operator B) had to be replaced due to inlay fracture (n=11), tooth fracture (n=4), hypersensitivities (n=3), or marginal gap formation (n=3). Seventy-seven inlays were in good condition (survival rate 89.9%, median survival time 4.2 years (95% confidence interval +/-0.25; survival analysis by Kaplan-Meier algorithm). Survival rate after 4 years was 97.4% for operator A, and 75.4% for operator B (p=0.002; Log Rank/Mantel-Cox) resulting in annual failure rates of 0.6% and 6.2%, respectively. The operators did not differently judge the clinical behaviour of the luting procedures (Mann-Whitney U-test, p>0.05). Independent of the operator and the used luting system, the following criteria significantly changed over time: color match, marginal integrity, tooth integrity, inlay integrity, sensitivity, hypersensitivity, and X-ray control (pinlay integrity (pinlays, only slight differences between the two luting systems were detectable. The operator influence on clinical outcome was clearly proven.

  14. Clinical utility of the KAMRA corneal inlay

    Science.gov (United States)

    Naroo, Shehzad Anjam; Bilkhu, Paramdeep Singh

    2016-01-01

    The treatment of presbyopia has been the focus of much scientific and clinical research over recent years, not least due to an increasingly aging population but also the desire for spectacle independence. Many lens and nonlens-based approaches have been investigated, and with advances in biomaterials and improved surgical methods, removable corneal inlays have been developed. One such development is the KAMRA™ inlay where a small entrance pupil is exploited to create a pinhole-type effect that increases the depth of focus and enables improvement in near visual acuity. Short- and long-term clinical studies have all reported significant improvement in near and intermediate vision compared to preoperative measures following monocular implantation (nondominant eye), with a large proportion of patients achieving Jaeger (J) 2 to J1 (~0.00 logMAR to ~0.10 logMAR) at the final follow-up. Although distance acuity is reduced slightly in the treated eye, binocular visual acuity and function remain very good (mean 0.10 logMAR or better). The safety of the inlay is well established and easily removable, and although some patients have developed corneal changes, these are clinically insignificant and the incidence appears to reduce markedly with advancements in KAMRA design, implantation technique, and femtosecond laser technology. This review aims to summarize the currently published peer-reviewed studies on the safety and efficacy of the KAMRA inlay and discusses the surgical and clinical outcomes with respect to the patient’s visual function. PMID:27274194

  15. Stereoacuity after small aperture corneal inlay implantation

    Directory of Open Access Journals (Sweden)

    Linn SH

    2017-01-01

    Full Text Available Steven H Linn,1 David F Skanchy,2 Tyler S Quist,3 Jordan D Desautels,4 Majid Moshirfar1,5 1Department of Clinical Research, HDR Research Center, Hoopes Vision, Draper, UT, 2McGovern Medical School, The University of Texas Health Science Center at Houston, TX, 3University of Utah School of Medicine, Salt Lake City, UT, 4Tufts University School of Medicine, Boston, MA, 5John A Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA Purpose: The aim of this study was to compare stereoacuity before and after KAMRA corneal inlay implantation for the correction of presbyopia.Patients and methods: This is a prospective study of 60 patients who underwent KAMRA inlay implantation. Patients were examined before and 6 months after surgery for stereoacuity, uncorrected distance visual acuity (UDVA, and uncorrected near visual acuity (UNVA.Results: The mean stereoacuity before surgery was 29.5±28.1 arcsec (range: 20–200 and at 6 months was 29.8±26.4 arcsec (range: 20–200. The decline in stereoacuity was not statistically significant. At 6 months follow-up, UDVA was 20/25 or better in all 60 patients and UNVA was J2 (20/25 or better in 51 (85% patients.Conclusion: There is no significant change in stereoacuity following KAMRA inlay implantation. The KAMRA inlay is a good treatment option for improving near vision in presbyopic patients while preserving stereoacuity and distance vision. Keywords: KAMRA, corneal inlay, AcuFocus, stereoacuity, presbyopia 

  16. A practice-based research network on the survival of ceramic inlay/onlay restorations.

    Science.gov (United States)

    Collares, Kauê; Corrêa, Marcos B; Laske, Mark; Kramer, Enno; Reiss, Bernd; Moraes, Rafael R; Huysmans, Marie-Charlotte D N J M; Opdam, Niek J M

    2016-05-01

    To evaluate prospectively the longevity of ceramic inlay/onlay restorations placed in a web-based practice-based research network and to investigate risk factors associated with restoration failures. Data were collected by a practice-based research network called Ceramic Success Analysis (CSA). 5791 inlay/onlay ceramic restorations were placed in 5523 patients by 167 dentists between 1994 and 2014 in their dental practices. For each restoration specific information related to the tooth, procedures and materials used were recorded. Annual failure rates (AFRs) were calculated and variables associated with failure were assessed by a multivariate Cox-regression analysis with shared frailty. The mean observation time was 3 years (maximum 15 years) of clinical service, and AFRs at 3 and 10 years follow up were calculated as 1.0% and 1.6%. Restorations with cervical outline in dentin showed a 78% higher risk for failure compared to restorations with margins in enamel. The presence of a liner or base of glass-ionomer cement resulted in a risk for failure twice as large as that of restorations without liner or base material. Restorations performed with simplified adhesive systems (2-step etch-and-rinse and 1-step self-etch) presented a risk of failure 142% higher than restorations performed with adhesives with bonding resin as a separate step (3-step etch-and-rinse and 2-step self-etch). 220 failures were recorded and the most predominant reason for failure was fracture of the restoration or tooth (44.5%). Ceramic inlay/onlay restorations made from several glass ceramic materials and applied by a large number of dentists showed a good survival. Deep cervical cavity outline, presence of a glass ionomer lining cement, and use of simplified adhesive systems were risk factors for survival. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Crack growth resistance of alumina, zirconia and zirconia toughened alumina ceramics for joint prostheses.

    Science.gov (United States)

    De Aza, A H; Chevalier, J; Fantozzi, G; Schehl, M; Torrecillas, R

    2002-02-01

    Mono-phase bio-ceramics (alumina and zirconia) are widely used as femoral heads in total hip replacements (THR) as an alternative to metal devices. Unfortunately, the orthopaedic community reports significant in-vivo failures. Material scientists are already familiar with composites like alumina zirconia. Since both are biocompatible, this could prove to be a new approach to implants. This paper deals with a new generation of alumina-zirconia nano-composites having a high resistance to crack propagation, and as a consequence may offer the option to improve lifetime and reliability of ceramic joint prostheses. The reliability of the above mentioned three bio-ceramics (alumina, zirconia and zirconia toughened alumina) for THR components is analysed based on the study of their slow crack-growth behaviour. The influence of the processing conditions on the microstructure development, of the zirconia toughened alumina composites and the effect of these microstructures, on its mechanical properties, are discussed.

  18. Cataract Surgery with a Refractive Corneal Inlay in Place

    OpenAIRE

    Stojanovic, N. R.; Panagopoulou, S. I.; Pallikaris, I. G.

    2015-01-01

    Purpose. To present a case of cataract surgery performed in a patient with a refractive corneal inlay in place. Methods. A 48-year-old female patient presented to our institute with bilateral cataract. The patient had undergone refractive corneal inlay implantation three years ago in her right, nondominant eye for presbyopia correction. Biometry and intraocular lens (IOL) power calculation were performed without removing the inlay. Phacoemulsification and IOL insertion were carried out in bot...

  19. The all-ceramic, inlay supported fixed partial denture. Part 1. Ceramic inlay preparation design: a literature review.

    Science.gov (United States)

    Thompson, M C; Thompson, K M; Swain, M

    2010-06-01

    The effect of cavity design is a controversial and underrated factor in the clinical success of ceramic inlays and inlay supported prosthesis. Many articles and studies have been conducted into the advantages and disadvantages of isolated aspects of preparation design, but lacking is a review of the most relevant papers which bring together a consensus on all the critical features. Hence, a review and analysis of cavity depth, width, preparation taper and internal line angles is warranted in our attempts to formulate preparation guidelines that will lead to clinically successful, all-ceramic inlay restorations and ceramic inlay supported prosthesis.

  20. Effect of immediate dentine sealing on the fracture strength of lithium disilicate and multiphase resin composite inlay restorations.

    Science.gov (United States)

    van den Breemer, Carline R G; Özcan, Mutlu; Cune, Marco S; van der Giezen, Rianne; Kerdijk, Wouter; Gresnigt, Marco M M

    2017-08-01

    Limited information is available on the effect of Immediate Dentin Sealing (IDS) on the fracture strength of indirect partial posterior restorations. This study evaluated the effect of IDS on the fracture strength and failure types of two indirect restorative materials. Standard MOD inlay preparations were made on sound molars (N=40, n=10 per group) and randomly divided into four groups to receive the inlay materials with and without the application of IDS: Group L-IDS-: Li 2 Si 2 O 5 (Lithium disilicate, IPS e.max) without IDS; Group L-IDS+: Li 2 Si 2 O 5 with IDS; Group MR-IDS-: Multiphase resin composite (MR, Lava Ultimate) without IDS; MR-IDS+: MR with IDS. Inlays made of L were etched with 5% hydrofluoric acid, and MR inlays were silica coated. After silanization, they were cemented using adhesive resin cement (Variolink Esthetic DC). The specimens were thermo-mechanically aged (1.2×10 6 cycles, 1.7Hz, 8000 cycles, 5-55°C) and then subjected to load to failure (1 mm/min). Failure types and locations of debondings were classified. Data were statistically analyzed using ANOVA, Mann Whitney U-test and Chi-square tests (α=0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated. After aging conditions, no apparent changes were observed in marginal integrity but occlusal wear facets were more common with MR than with L (p0.05). Immediate dentin sealing improves adhesion, and thereby the fracture strength of inlays made of lithium disilicate but not that multiphase resin composite. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Clinical utility of the KAMRA corneal inlay

    Directory of Open Access Journals (Sweden)

    Naroo SA

    2016-05-01

    Full Text Available Shehzad Anjam Naroo, Paramdeep Singh Bilkhu Ophthalmic Research Group, School of Life & Health Sciences, Aston University, Birmingham, UK Abstract: The treatment of presbyopia has been the focus of much scientific and clinical research over recent years, not least due to an increasingly aging population but also the desire for spectacle independence. Many lens and nonlens-based approaches have been investigated, and with advances in biomaterials and improved surgical methods, removable corneal inlays have been developed. One such development is the KAMRA™ inlay where a small entrance pupil is exploited to create a pinhole-type effect that increases the depth of focus and enables improvement in near visual acuity. Short- and long-term clinical studies have all reported significant improvement in near and intermediate vision compared to preoperative measures following monocular implantation (nondominant eye, with a large proportion of patients achieving Jaeger (J 2 to J1 (~0.00 logMAR to ~0.10 logMAR at the final follow-up. Although distance acuity is reduced slightly in the treated eye, binocular visual acuity and function remain very good (mean 0.10 logMAR or better. The safety of the inlay is well established and easily removable, and although some patients have developed corneal changes, these are clinically insignificant and the incidence appears to reduce markedly with advancements in KAMRA design, implantation technique, and femtosecond laser technology. This review aims to summarize the currently published peer-reviewed studies on the safety and efficacy of the KAMRA inlay and discusses the surgical and clinical outcomes with respect to the patient’s visual function. Keywords: presbyopia, refractive surgery, implants, cornea

  2. Indirect posterior composite inlays and onlays.

    Science.gov (United States)

    Landman, P

    1994-01-01

    Indirect posterior composite inlays and onlays are a valuable part of the cosmetic dentist's repertoire of services. They fulfill most of the requirements for an esthetic alternative to the previously considered amalgam, gold, porcelain, and directly placed composite restorations. As in all other cosmetic dental procedures, attention to detail is essential for success. Improving technology will continue to have an impact on the place these restorations occupy in future cosmetic practice.

  3. Comparison of the operation of arthroscopic tibial inlay and traditional tibial inlay for posterior cruciate ligament reconstruction.

    Science.gov (United States)

    Lu, Daifeng; Xiao, Mochao; Lian, Yongyun; Zhou, Yong; Liu, Xuefeng

    2014-01-01

    To perform dual-bundle reconstruction of posterior cruciate ligament using full arthroscopic tibial inlay technology with self-designed tibia tunnel drilling system and to compare the effect of arthroscopic tibial inlay versus traditional technique for posterior cruciate ligament reconstruction. 32 patients were randomly divided into experiment group (improved tibial inlay, n = 17) and control group (traditional tibial inlay, n = 15). Self-designed tibia tunnel drill system was used to produce intraoperative deep-limited bone tunnel. During follow-up, the location of the bone block and the healing situation were checked by knee X-ray and spiral CT scan. Blood loss, operation time and nerve vascular injuries were evaluated. Mean intraoperative blood loss was 123.53 ± 74.05 ml in the improved tibial inlay group compared with 332 ± 114.26 ml in the traditional tibial inlay group (t = 6.12, P inlay group compared with 346.37 ± 59.67 min in the traditional tibial inlay group (t = 5.19, P inlay technique compared with 14 negative cases and 2 positive cases of traditional tibial Inlay technique. The X-ray and spiral CT scan showed the location of the bone block were perfect and healed well with the patent who received improved tibial inlay technology after 12 weeks postoperatively. Accurate depth-limited bone tunnel can be produced by the tibia tunnel drill system with minor trauma, less bleeding and reducing of nerves or vessels and the recent clinical effects of PCL reconstruction were pretty good.

  4. Implantable inlay devices for presbyopia: the evidence to date

    Science.gov (United States)

    Arlt, EM; Krall, EM; Moussa, S; Grabner, G; Dexl, AK

    2015-01-01

    By 2020, it is estimated that 2.1 billion people will be presbyopic, and the demand for spectacle independence in this group is growing. This review article provides an overview of the three commercially available corneal inlays for the correction of presbyopia. Safety, efficacy, visual outcomes, and complications are analyzed for all three inlays according to published peer-reviewed data. PMID:25609913

  5. Fracture strength of teeth restored with ceramic inlays and overlays.

    Science.gov (United States)

    Morimoto, Susana; Vieira, Glauco Fioranelli; Agra, Carlos Martins; Sesma, Newton; Gil, Carlos

    2009-01-01

    This study evaluated the fracture strength of teeth restored with bonded ceramic inlays and overlays compared to sound teeth. Thirty sound human maxillary premolars were assigned to 3 groups: 1- sound/unprepared (control); 2- inlays and 3- overlays. The inlay cavity design was Class II MOD preparation with an occlusal width of 1/2 of the intercuspal distance. The overlay cavity design was similar to that of the inlay group, except for buccal and palatal cusp coverage The inlay and overlay groups were restored with feldspathic porcelain bonded with adhesive cement. The specimens were subjected to a compressive load until fracture. Data were analyzed statistically by the Kruskal-Wallis test at 5% significance level. The fracture strength means (KN) were: Sound/unprepared group = 1.17, Inlay group= 1.17, and Overlay group = 1.14. There were no statistically significant differences (p>0.05) among the groups. For inlays and overlays, the predominant fracture mode involved fragments of one cusp (70% of simple fractures). The fracture strength of teeth restored with inlay and overlay ceramics with cusp coverage was similar to that of intact teeth.

  6. Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

    Science.gov (United States)

    Kameyama, Atsushi; Bonroy, Kim; Elsen, Caroline; Lührs, Anne-Katrin; Suyama, Yuji; Peumans, Marleen; Van Meerbeek, Bart; De Munck, Jan

    2015-01-01

    The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

  7. IBA analysis of a possible therapeutic ancient tooth inlay

    Science.gov (United States)

    Andrade, E.; Pineda, J. C.; Zavala, E. P.; Murillo, G.; Chavez, R.; Lazcurain, R.; Espinosa, Ma. L.; Villanueva, O.

    1998-03-01

    Five pre-Columbian human teeth from the same skeleton found during excavation in an ancient ceremonial center in Mexico, have been analyzed by two conventional Ion Beam Analysis (IBA) techniques: PIXE and 4He RBS. The anthropologists have estimated that the skeleton is about 2000 years old. X-ray radiography studies of one of these teeth have revealed that they contain an inlay in the tooth crown. The IBA methods have been used to study the inlay materials and also the tooth enamel. The IBA studies show that the tooth inlay materials have almost the same atomic composition as the tooth enamel. These results suggest that the tooth inlay were made for therapeutic purposes, using healthy tooth grains as inlay materials which were glued into the prepared teeth to fill it up.

  8. Bioactive glass microspheres as osteopromotive inlays in macrotextured surfaces of Ti and CoCr alloy bone implants: trapezoidal surface grooves without inlay most efficient in resisting torsional forces.

    Science.gov (United States)

    Keränen, Pauli; Moritz, Niko; Alm, Jessica J; Ylänen, Heimo; Kommonen, Bertel; Aro, Hannu T

    2011-10-01

    We have tested the efficacy of porous bioactive glass (BG) inlays in enhancement of implant osseointegration. A total of 24 sheep underwent bilateral surgical implantation of three parallel implants on the anteromedial cortical surface of each tibia. The disc-shaped implants made of Ti6Al4V or cobalt chromium (CoCr) alloys had two parallel surface grooves (trapezoidal space with bottom widening) filled with sintered 100% bioactive glass microspheres or a selected mixture of bioactive and biocompatible glass microspheres. The surface of uncoated control implants was smooth, grit-blasted or had unfilled grooves. A subgroup of control smooth CoCr implants was coated with two or three BG layers. Implant incorporation with bone was evaluated using torque testing to failure, scanning electron microscopy and morphometry at 12 and 25 weeks. A total of 144 in vivo implants and 16 ex vivo cemented control implants were analyzed. Control Ti6Al4V implants with unfilled trapezoidal grooves showed highest torsional failure loads with excellent ingrowth of new bone and remodeling of ingrown bone into lamellar bone. Implants with BG inlays and microroughened control Ti6Al4V implants showed significantly lower torsional failure loads than control Ti6Al4V implants with unfilled grooves. In conclusion, BG inlays failed to enhance biological implant fixation. Macrotextured surface was more effective than grit-blasting in promotion of mechanical incorporation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Fracture resistance of three ceramic inlay-retained fixed partial denture designs. An in vitro comparative study.

    Science.gov (United States)

    Mohsen, Cherif A

    2010-10-01

    The fracture resistance of ceramic inlay-retained fixed partial dentures (CIRFPDs) was studied. Thirty CIRFPDs were constructed using ice zircon milled ceramic material. Specimens were divided into three groups, 10 specimens each, according to the abutment preparation: inlay-shaped (occluso-proximal inlay + proximal box), tub-shaped (occluso-proximal inlay), and proximal box-shaped preparations. Each group was then subdivided into two subgroups of five specimens each, according to the span of the edentulous area representing a missing premolar or molar. All specimens were subjected to a fracture resistance test. CIRFPDs with inlay-shaped retainers showed the highest fracture resistance values for missing premolars and molars. CIRFPDs with box-shaped retainers showed lower fracture resistance values. Statistical analysis revealed a significant difference between the three tested CIRFPD designs. There was a statistically significant difference between CIRFPDs constructed for the replacement of molars and those constructed for the replacement of premolars. The CIRFPD constructed for the replacement of molars gave lower fracture resistance values with the three tested designs. All the fracture resistance values obtained in this study were superior to the assumed maximum mastication forces. Failure mode was delamination and chipping of the veneering material. There was a statistically significant difference between the three designs of CIRPFDs tested. There was a statistically significant difference between CIRFPDs constructed for the replacement of molars than those constructed for the replacement of premolars. The CIRFPDs constructed for the replacement of molars gave lower fracture resistance values with the three tested designs. All fracture resistance values obtained in this study were superior to the assumed maximum mastication forces. © 2010 by The American College of Prosthodontists.

  10. Unilateral Keratectasia Treated with Femtosecond Fashioned Intrastromal Corneal Inlay

    Science.gov (United States)

    Jadidi, Khosrow; Hasanpour, Hossein

    2017-01-01

    Purpose: In this case report, we describe the surgical procedure of corneal inlay preparation and corneal pocket creation using a femtosecond laser system. Case Report: A 7-year-old girl who presented with unilateral paracentral corneal thinning underwent the surgical procedure of corneal inlay. Preoperatively, the refraction was +10.00-6.00 × 170. One month after the procedure, astigmatism and hyperopia were decreased and the refraction was +5.00-1.25 × 110. Conclusion: Femtosecond laser–assisted pocket creation for the implantation of corneal inlays offers accuracy of pocket parameters, enhancing predictability, resulting in better final outcomes, and improving the safety of the procedure. PMID:28791068

  11. The structural analysis of socket inlays of the hip endoprosthesis

    Directory of Open Access Journals (Sweden)

    Robert Karpiński

    2016-12-01

    Full Text Available The paper presents results of the preliminary structural analysis of socket inlays model of the endoprosthesis of the hip joint. Basics of anatomy and biomechanical analysis of the hip joint were introduced. The prototype of socket inlay of the hip endoprosthesis was modeled using Solid Edge ST8 software. After determining physical properties of structural materials for socket inlays, the Finite Elements Analysis of the model was conducted using SolidWorks software under various load conditions. Finally the results of analysis were presented.

  12. Fracture strength of minimally prepared resin bonded CEREC inlays.

    Science.gov (United States)

    Tsitrou, Effrosyni; Helvatjoglou-Antoniades, Maria; Pahinis, Kimon; van Noort, Richard

    2009-01-01

    This study compared the structural integrity and fracture mode of teeth restored with traditionally and minimally prepared resin-bonded CAD/CAM inlays fabricated from the same material. Forty intact maxillary premolars were used and divided into four groups. Two groups were prepared according to a traditional inlay preparation design (2.0 mm occlusal reduction, a 1.5 mm wide proximal box and divergent walls) and two groups were prepared according to a newly proposed minimal preparation design (round shaped cavity with 1.0 mm occlusal reduction, a U-shaped proximal box 1.0 mm wide and parallel walls). Two restorative systems were tested: a composite system comprised of Paradigm MZ100 (3M ESPE) blocks and RelyX Unicem (3M ESPE) resin cement and a ceramic system comprised of ProCAD blocks (Ivoclar-Vivadent) and Variolink II (Ivoclar-Vivadent) resin cement. The inlays were cemented according to the manufacturers' instructions. Each specimen was loaded axially to its occlusal surface at a crosshead speed of 0.5 mm/minute in a universal testing machine until fracture. The fracture load data were analyzed using ANOVA, comparing inlays of the same restorative material. Also, the mode of fracture of the inlays was recorded and analyzed using a non-parametric test (Kruskal-Wallis). In the composite system case, the mean fracture load and SD were 1322 N (+/- 445) for the traditional inlays and 1511 N (+/- 395) for the minimal inlays, while in the ceramic system case, those values were 1135N (+/- 450) for the traditional inlays and 1761 N (+/- 494) for the minimal inlays. Statistical analysis of the results showed that there was no statistically significant difference between the two designs for the composite system, while for the ceramic system, the minimally prepared teeth showed higher mean fracture strength. Non-parametric analysis (Kruskal-Wallis) of the mode of fracture showed that there was no statistically significant difference between traditionally and minimally

  13. Implantable inlay devices for presbyopia: the evidence to date

    Directory of Open Access Journals (Sweden)

    Arlt EM

    2015-01-01

    Full Text Available EM Arlt, EM Krall, S Moussa, G Grabner, AK DexlDepartment of Ophthalmology, Paracelsus Medical University Salzburg, Salzburg, Austria Abstract: By 2020, it is estimated that 2.1 billion people will be presbyopic, and the demand for spectacle independence in this group is growing. This review article provides an overview of the three commercially available corneal inlays for the correction of presbyopia. Safety, efficacy, visual outcomes, and complications are analyzed for all three inlays according to published peer-reviewed data. Keywords: corneal inlay, presbyopia, refractive surgery, small-aperture inlay, corneal reshaping inlay, refractive optic inlay

  14. Unilateral keratectasia treated with femtosecond fashioned intrastromal corneal inlay

    Directory of Open Access Journals (Sweden)

    Khosrow Jadidi

    2017-01-01

    conclusion: Femtosecond laser–assisted pocket creation for the implantation of corneal inlays offers accuracy of pocket parameters, enhancing predictability, resulting in better final outcomes, and improving the safety of the procedure.

  15. Microleakage of different provisionalization techniques for class I inlays

    Directory of Open Access Journals (Sweden)

    Selim Erkut

    2013-03-01

    Conclusion: The microleakage in class I inlay cavities could be reduced by the application of dentin-bonding agents after cavity preparation followed by the placement of light-polymerized provisional restorative materials.

  16. Inlay buccal mucosal graft for reoperative posterior urethroplasty

    Directory of Open Access Journals (Sweden)

    Shou-Hung Tang

    2012-04-01

    Full Text Available Posterior urethral distraction injury following major pelvic trauma is a surgical challenge. Although rarely seen, cases of failure after formal urethral reconstruction are even more problematic. We adapted the concept of augmented free buccal mucosal grafts, which have been successful in anterior urethroplasty, for repairing the posterior urethra in these rare cases with the aim of reducing the likelihood of penile chordee postoperatively. During 2007–2009, four patients were candidates for the proposed procedure because they had received formal transperineal urethral reconstruction but were unable to urinate through the urethra. The urethra was approached transperineally and opened in the midline, rather than divided. Buccal mucosal grafts of an appropriate size were placed in the created urethral groove from 4- to 8 o’clock in the lithotomy view. After the procedure, the urethral catheter was kept for 3 weeks. All patients voided through the urethra after the procedure. The maximal postoperative urinary flow rates were between 12–15 ml/seconds in all cases for a follow-up period of 18–30 months. The recurrence rate was 50% (2/4. Recurrent strictures were minor, and they showed a web-like stricture ring near the suture line. Restricture within 6 months of surgery responded well to endoscopic internal urethrotomy plus dilatations. In conclusion, without further compromising urethral length, reoperative posterior urethroplasty with the inlay grafting technique can be considered in selective cases.

  17. Inlay buccal mucosal graft for reoperative posterior urethroplasty.

    Science.gov (United States)

    Tang, Shou-Hung; Kao, Chien-Chang; Wu, Seng-Tang; Meng, En; Cha, Tai-Lung

    2012-04-01

    Posterior urethral distraction injury following major pelvic trauma is a surgical challenge. Although rarely seen, cases of failure after formal urethral reconstruction are even more problematic. We adapted the concept of augmented free buccal mucosal grafts, which have been successful in anterior urethroplasty, for repairing the posterior urethra in these rare cases with the aim of reducing the likelihood of penile chordee postoperatively. During 2007-2009, four patients were candidates for the proposed procedure because they had received formal transperineal urethral reconstruction but were unable to urinate through the urethra. The urethra was approached transperineally and opened in the midline, rather than divided. Buccal mucosal grafts of an appropriate size were placed in the created urethral groove from 4- to 8 o'clock in the lithotomy view. After the procedure, the urethral catheter was kept for 3 weeks. All patients voided through the urethra after the procedure. The maximal postoperative urinary flow rates were between 12-15 ml/seconds in all cases for a follow-up period of 18-30 months. The recurrence rate was 50% (2/4). Recurrent strictures were minor, and they showed a web-like stricture ring near the suture line. Restricture within 6 months of surgery responded well to endoscopic internal urethrotomy plus dilatations. In conclusion, without further compromising urethral length, reoperative posterior urethroplasty with the inlay grafting technique can be considered in selective cases. Copyright © 2012. Published by Elsevier B.V.

  18. The effect of box preparation on the strength of glass fiber-reinforced composite inlay-retained fixed partial dentures.

    Science.gov (United States)

    Ozcan, Mutlu; Breuklander, Marijn H; Vallittu, Pekka K

    2005-04-01

    Nonstandardized box dimensions for inlay-retained fixed partial dentures (FPDs) may result in uneven distribution of the forces on the connector region of such restorations. The objective of this in vitro study was to evaluate the effect of box dimensions on the initial and final failure strength of inlay-retained fiber-reinforced composite (FRC) FPDs. Twenty-one inlay-retained FPDs were prepared using FRC (everStick) frameworks with unidirectional fiber reinforcement between mandibular first premolars and first molars. Boxes were prepared using conventional inlay burs (Cerinlay), and small and large ultrasonic tips (SONICSYS approx). Box dimensions were measured after preparation with a digital micrometer. All restorations were subjected to thermal cycling (6000 cycles, 5 degrees C-55 degrees C). Fracture testing was performed in a universal testing machine (1 mm/min). Acoustic emission signals were monitored during loading of the specimens. Initial and final fracture strength values (2-way ANOVA, Bonferroni post hoc tests, alpha =.05) and failure types (Fisher exact test) were statistically compared for each group. Significant differences (P =.0146 and P =.0086) were observed between the groups in the dimensions of the boxes prepared using conventional burs buccolingually (2.8-3.0 mm in molars, 3.1-4.3 mm in premolars) and the small size (2.5-2.9, 2.9-3.8 mm) or large size (2.6-3.8, 3.2-4.9 mm) ultrasonic tips for the premolars and the molars, respectively. No significant differences were found at the initial and final failures between the conventionally prepared group (842 +/- 267 N, 1161 +/- 428 N) and those prepared with either small (1088 +/- 381 N, 1320 +/- 380 N) or large ultrasonic tips (1070 +/- 280 N, 1557 +/- 321 N), respectively. The failure analysis demonstrated no significant difference in failure types but predominant delamination of the veneering resin (85%) in all experimental groups. According to acoustic emission tests, a higher energy level was

  19. Reuse of activated alumina

    Energy Technology Data Exchange (ETDEWEB)

    Hobensack, J.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Activated alumina is used as a trapping media to remove trace quantities of UF{sub 6} from process vent streams. The current uranium recovery method employs concentrated nitric acid which destroys the alumina pellets and forms a sludge which is a storage and disposal problem. A recently developed technique using a distilled water rinse followed by three dilute acid rinses removes on average 97% of the uranium, and leaves the pellets intact with crush strength and surface area values comparable with new material. Trapping tests confirm the effectiveness of the recycled alumina as UF{sub 6} trapping media.

  20. Nonlinear dimensionality reduction by locally linear inlaying.

    Science.gov (United States)

    Hou, Yuexian; Zhang, Peng; Xu, Xingxing; Zhang, Xiaowei; Li, Wenjie

    2009-02-01

    High-dimensional data is involved in many fields of information processing. However, sometimes, the intrinsic structures of these data can be described by a few degrees of freedom. To discover these degrees of freedom or the low-dimensional nonlinear manifold underlying a high-dimensional space, many manifold learning algorithms have been proposed. Here we describe a novel algorithm, locally linear inlaying (LLI), which combines simple geometric intuitions and rigorously established optimality to compute the global embedding of a nonlinear manifold. Using a divide-and-conquer strategy, LLI gains some advantages in itself. First, its time complexity is linear in the number of data points, and hence LLI can be implemented efficiently. Second, LLI overcomes problems caused by the nonuniform sample distribution. Third, unlike existing algorithms such as isometric feature mapping (Isomap), local tangent space alignment (LTSA), and locally linear coordination (LLC), LLI is robust to noise. In addition, to evaluate the embedding results quantitatively, two criteria based on information theory and Kolmogorov complexity theory, respectively, are proposed. Furthermore, we demonstrated the efficiency and effectiveness of our proposal by synthetic and real-world data sets.

  1. Resultados de miringoplastia Inlay com cartilagem de tragus Inlay tragus cartilage miringoplasty results

    Directory of Open Access Journals (Sweden)

    I.G.F. Couto

    2004-08-01

    Full Text Available A utilização de cartilagem de tragus para o fechamento de perfurações de membrana timpânica (MT com acesso transcanal foi primeiramente descrito por Eavey em 1998 com excelentes resultados quanto à pega do enxerto e vantagens como facilidade técnica, rapidez e conforto pós-operatório ao paciente. OBJETIVO: Avaliar os resultados da miringoplastia inlay com cartilagem de tragus em pacientes operados no serviço de Otorrinolaringologia do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo nos últimos três anos. FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODO: Foram utilizadas para esse estudo 32 cirurgias realizadas no serviço de Otorrinolaringologia do Hospital das Clínicas de Ribeirão Preto no período de 2000 a 2003 em pacientes com diagnóstico de otite média crônica simples com perfuração de membrana timpânica de até 5mm de diâmetro e sem contra-indicações para realização de procedimento transcanal. RESULTADOS: Foi observado fechamento completo das perfurações de MT em 28 cirurgias das 32 realizadas perfazendo 87,5% de sucesso. DISCUSSÃO: O presente estudo manteve o alto índice de sucesso no fechamento de perfurações de MT com os princípios da técnica de Eavey descrito em estudos anteriores, mesmo com algumas modificações em relação à técnica original. CONCLUSÃO: A miringoplastia inlay com cartilagem de tragus em forma de asa de borboleta tem alto índice de sucesso no fechamento das perfurações de MT de até 5mm de diâmetro em casos de otite média crônica simples com orelha média saudável. Promove, ainda, maior conforto e menor morbidade ao paciente.The use of tragus cartilage to close tympanic membrane (TM perforations with transcanal approach was first described by Eavey in 1998 with excellent results for graft "take-rate" and with advantages such as technique ease, rapidity and postoperative patient comfort. AIM: To evaluate the inlay

  2. Biomechanical examination of inlay geometries--is there a basic biomechanical principle?

    Science.gov (United States)

    Arnetzl, G V; Arnetzl, G

    2009-01-01

    In this in vitro study, all-ceramic inlays were subjected to a static strength test. The material used in this case was Vita Mark II ceramic (Vita-Zahnfabrik, Bad Säckingen, Germany). The goal of the study was to evaluate two different inlay preparations with differently designed ceramic inlays resulting from it, to determine which offered the greatest possible resistance in static fracture loading tests. Tooth 36 on the model, provided with a standard preparation with a level floor, served as the test object. Two inserts were produced: one with classical preparation pattern, the other with a modified shape of the cavity floor. In one inlay design, the cavity floor was designed according to the guidelines valid for all-ceramic inlay restorations; in the second inlay design, a differently shaped cavity floor was selected to exclusively meet the requirements of the ceramic material. Impressions were then taken, and inlays were designed and produced by means of CAD/CAM technology. Lower fracture strength with mean fracture load values of ca 66.6 N was shown for traditional inlay preparations with a cavity floor segment designed as box. The mean fracture strength of the inlay design consisting of the same material with a hemispherical cavity floor segment was 84.9 (N), 27.5% greater. The question arises whether it is possible, independently of the ceramic used, to achieve an increase in strength by modifying the design of the inlay.

  3. [A three-year clinical evaluation of ceramic optimized polymer posterior inlays].

    Science.gov (United States)

    Xu, Quan-Lin; Ji, Pei-Hong; Ba, Yong; Jiang, Zhong-Ming

    2006-10-01

    To evaluate the clinical results of ceramic optimized polymer (Targis) posterior inlays. 345 type I cavities were divided into two groups: 170 in Targis inlays group (42 premolars and 128 molars) and 175 in control group (composite resin inlays, 45 premolars and 130 molars). The clinical effects of Targis inlays and composite resin inlays in posterior teeth were compared in marginal discoloration, marginal adaption, secondary caries, anatomic shape integrity, fractures of tooth and color match 3 years later. The data were analyzed using Chi-square test. 3 years after treatment, 166 Targis inlays were followed up, 2 had marginal discoloration, 158 had good marginal adaption, 162 had anatomic shape integrity, 1 had secondary caries, 161 had color match, and 5 had fractures of teeth. 169 composite resin inlays were followed up, 27 had marginal discoloration, 134 had good marginal adaption, 150 had anatomic shape integrity, 20 had secondary caries, 164 had color match,5 had fractures of teeth. The marginal discoloration, marginal adaption, secondary caries, anatomic shape integrity of Targis inlays were better than that of composite resin inlays (P 0.05). Targis posterior inlays is a good newly developed prosthesis.

  4. Three-dimensional modeling of metabolic species transport in the cornea with a hydrogel intrastromal inlay.

    Science.gov (United States)

    Pinsky, Peter M

    2014-05-15

    Intrastromal inlays for refractive correction of presbyopia are being adopted into clinical practice. An important concern is the effect of the inlay on the long-term health of the cornea due to disturbances in the concentration profiles of metabolic species. A three-dimensional metabolic model for the cornea is employed to investigate oxygen, glucose, and lactate ion transport in the cornea and to estimate changes in species concentrations induced by the introduction of a hydrogel inlay. A reaction-diffusion metabolic model, appropriate for highly oxygen-permeable hydrogel inlays, is used to describe cellular consumption of oxygen and glucose and production of lactic acid. A three-layer corneal geometry (epithelium, stroma, endothelium) is employed with a hydrogel inlay placed under a lamellar flap. The model is solved numerically by the finite element method. For a commercially available hydrogel material with a relative inlay diffusivity of 43.5%, maximum glucose depletion and lactate ion accumulation occur anterior to the inlay and both are less than 3%. Below 20% relative diffusivity, glucose depletion and lactate ion accumulation increase exponentially. Glucose depletion increases slightly with increasing depth of inlay placement. The flux of metabolic species is modified by an inlay, depending on the inlay relative diffusivity. For commercially available hydrogel materials and a typical inlay design, predicted changes in species concentrations are small when compared to the variation of concentrations across the normal cornea. In general, glucose depletion and lactate ion accumulation are highly sensitive to inlay diffusivity and somewhat insensitive to inlay depth. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  5. Tactile shoe inlays for high speed pressure monitoring

    DEFF Research Database (Denmark)

    Drimus, Alin; Mátéfi-Tempfli, Stefan

    2015-01-01

    This work describes the development of flexible tactile sensor shoe inlays for humanoid robots. Their design is based on a sandwich structure of flexible layers with a thin sheet of piezoresistive rubber as main transducer element. The layout and patterning of top and bottom electrodes give 1024...

  6. Evaluation of concrete inlay for continuously reinforced concrete pavement rehabilitation.

    Science.gov (United States)

    2010-06-01

    In 1996, WisDOT constructed a concrete inlay test section on I43 in Manitowoc County. The existing pavement was CRCP constructed in 1978 and was badly deteriorated with punchouts. In the area of the 2777foot test section, the existing paveme...

  7. Ceramic Inlays: Effect of Mechanical Cycling and Ceramic Type on Restoration-dentin Bond Strength.

    Science.gov (United States)

    Trindade, F Z; Kleverlaan, C J; da Silva, L H; Feilzer, A J; Cesar, P F; Bottino, M A; Valandro, L F

    2016-01-01

    This study aimed to evaluate the bond strength between dentin and five different ceramic inlays in permanent maxillary premolars, with and without mechanical cycling. One hundred permanent maxillary premolars were prepared and divided into 10 groups (n=10) according to the ceramic system (IPS e.Max Press; IPS e.Max CAD; Vita PM9; Vita Mark II; and Vita VM7) and the mechanical cycling factor (with and without [100 N, 2 Hz, 1.2×10(6) cycles]). The inlays were adhesively cemented, and all of the specimens were cut into microbars (1×1 mm, nontrimming method), which were tested under microtensile loading. The failure mode was classified and contact angle, roughness, and microtopographic analyses were performed on each ceramic surface. The mechanical cycling had a significant effect (p=0.0087) on the bond strength between dentin and IPS e.max Press. The Vita Mark II group had the highest bond strength values under both conditions, with mechanical cycling (9.7±1.8 MPa) and without (8.2±1.9 MPa), while IPS e.Max CAD had the lowest values (2.6±1.6 and 2.2±1.4, respectively). The adhesive failure mode at the ceramic/cement interface was the most frequent. Vita Mark II showed the highest value of average roughness. IPS e.max Press and Vita Mark II ceramics presented the lowest contact angles. In conclusion, the composition and manufacturing process of ceramics seem to have an influence on the ceramic surface and resin cement bond strength. Mechanical cycling did not cause significant degradation on the dentin and ceramic bond strength under the configuration used.

  8. Survival Rate of Resin and Ceramic Inlays, Onlays, and Overlays: A Systematic Review and Meta-analysis.

    Science.gov (United States)

    Morimoto, S; Rebello de Sampaio, F B W; Braga, M M; Sesma, N; Özcan, M

    2016-08-01

    This systematic review and meta-analysis aimed to evaluate the survival rate of ceramic and resin inlays, onlays, and overlays and to identify the complication types associated with the main clinical outcomes. Two reviewers searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials for articles published between 1983 through April 2015, conforming to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for systematic reviews. Clinical studies meeting the following criteria were included: 1) studies related to resin and ceramic inlays, onlays, and overlays; 2) prospective, retrospective, or randomized controlled trials conducted in humans; 3) studies with a dropout rate of less than 30%; and 4) studies with a follow-up longer than 5 y. Of 1,389 articles, 14 met the inclusion criteria. The meta-regression indicated that the type of ceramic material (feldspathic porcelain vs. glass-ceramic), study design (retrospective vs. prospective), follow-up time (5 vs. 10 y), and study setting (university vs. private clinic) did not affect the survival rate. Estimated survival rates for glass-ceramics and feldspathic porcelain were between 92% and 95% at 5 y (n = 5,811 restorations) and were 91% at 10 y (n = 2,154 restorations). Failures were related to fractures/chipping (4%), followed by endodontic complications (3%), secondary caries (1%), debonding (1%), and severe marginal staining (0%). Odds ratios (95% confidence intervals) were 0.19 (0.04 to 0.96) and 0.54 (0.17 to 1.69) for pulp vitality and type of tooth involved (premolars vs. molars), respectively. Ceramic inlays, onlays, and overlays showed high survival rates at 5 y and 10 y, and fractures were the most frequent cause of failure. © International & American Associations for Dental Research 2016.

  9. In vitro two-body wear of inlay-onlay composite resin restoratives.

    Science.gov (United States)

    Burgoyne, A R; Nicholls, J I; Brudvik, J S

    1991-02-01

    Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resins using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surface was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.

  10. Fracture risk of lithium-disilicate ceramic inlays: a finite element analysis.

    Science.gov (United States)

    Holberg, Christof; Winterhalder, Philipp; Wichelhaus, Andrea; Hickel, Reinhard; Huth, Karin

    2013-12-01

    In the present study, lithium-disilicate ceramic inlays should be analyzed biomechanically according to their thickness and dimension, and it should be clarified as to whether there is a significant relationship between the inlay volume and the induced tensile stress level. Using a new parametric CAD modeling procedure, 27 lithium-disilicate ceramic inlays with various parameters of "depth", "width", "angle" and restoration volume were generated. These inlays were integrated into the CAD model of a lower molar created from the CT data of an anatomical preparation. The resulting CAD models were, finally, three-dimensionally cross-linked to FEM models. After applying a compressive force of 200 N, Principal Tensile Stresses (PTSs) could be measured in the inlay. The values were subject to statistical analysis afterwards. The volume of the inlay restorations varied between 35.7 mm(3) and 82.5mm(3). The maximum PTS values (n=10) only showed a slight negative correlation with the inlay volume. The correlation coefficient according to Spearman was -0.082 (p ≤ 0.001). If the highest 1000 PTS values of each inlay were considered (n=1000), the correlation coefficient was further reduced to +0.068 (p ≤ 0.001). No significant correlation between the inlay volume and the induced PTS level could be detected. Under the conditions and limitations of the present FEM study, the inlay volume did not significantly influence the tensile stress level of ceramic inlays. The results may support the thesis that volume-reduced all-ceramic inlays might not have an increased fracture risk. Further studies are needed to confirm this. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Alumina Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2002-02-01

    The Alumina Technology Roadmap outlines a comprehensive long-term research and development plan that defines the industry's collective future and establishes a clear pathway forward. It emphasizes twelve high-priority R&D areas deemed most significant in addressing the strategic goals.

  12. Bauxite and alumina

    Science.gov (United States)

    Bray, E.L.

    2010-01-01

    The article reports on the global market performance of bauxite and alumina in 2009 and presents an outlook for their 2010 performance. There were only several U.S. states that could produce bauxite and bauxitic clays including Georgia, Arkansas, and Alabama. The prices for imported refractory-grade calcined bauxite ranged between 426 U.S. dollars and 554 dollars per ton.

  13. alumina solid electrolyte

    Indian Academy of Sciences (India)

    -β/β -alumina; solid electrolyte; calcium impurity; specific resistance. 1. Introduction. Since its development in the 1980s, the Na/S battery has been one of the most promising candidates for energy storage applications. The Na/S battery functions based on the elec- trochemical reaction between sodium and sulphur to form.

  14. alumina solid electrolyte

    Indian Academy of Sciences (India)

    alumina was synthesized using a solid-state reaction. The changes in ... sive, because of its abundant lowcost raw materials and is suitable for high-volume mass production. The battery is composed of a sodium anode, a sulphur cathode, and. Na. +.

  15. Effects of femtosecond and excimer lasers on implanted KAMRA corneal inlay in animal models.

    Science.gov (United States)

    Sammouh, F K; Baban, T A; Dandan, W N; Warrak, E L

    2017-05-01

    To evaluate the effect of femtosecond laser and excimer laser on an intracorneal inlay (KAMRA ® ) implanted in animal models. Femtosecond laser was used to create corneal intrastromal pockets at 250μm depth in five porcine eyes. Four intact KAMRA inlays, examined by slit-lamp biomicroscopy and light microscopy, were implanted in the pocket of four eyes. A standard LASIK flap was created above each implanted inlay in the four eyes using a femtosecond laser with flap thicknesses of 150μm, 130μm, 110μm and 90μm. In the fifth porcine eye, a LASIK flap was created using femtosecond laser at 110μm depth, and a fifth inlay was then implanted in the 250μm pocket. Excimer laser ablation was performed under the flap targeting a -3.00 refraction. The inlay was then explanted, examined and reimplanted in the same pocket followed by a second similar excimer laser ablation. Significant burn, shrinkage and distortion of microholes were noted in all the first four inlays following the femtosecond laser flap creation at all the various flap thicknesses. The damage was noted to be more prominent as the distance between the flap and inlay decreased. No apparent effect was noted on the fifth inlay following repeated excimer laser ablations. Unlike excimer laser, femtosecond laser appears to be hazardous and damaging to the intracorneal KAMRA inlay when applied above it. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. An 8-year evaluation of sintered ceramic and glass ceramic inlays processed by the Cerec CAD/CAM system

    DEFF Research Database (Denmark)

    Pallesen, U.; Dijken van, J.W.V.

    2000-01-01

    sensitivity was reported by one patient for 8 months. Of the 32 inlays evaluated during the 8 yr, 3 failed due to fracture of the material. No secondary caries was found adjacent to the inlays. No significant differences in the clinical performance were found between inlays made of the two ceramics. It can......The purpose of this study was to evaluate Cerec CAD/CAM inlays processed of two industrially made machinable ceramics during an 8-yr follow-up period. Each of 16 patients received two similar ceramic inlays. Half the number of the inlays were made of a feldspathic (Vita Mark II) and the other...... of a glass ceramic (Dicor MGC) block. The inlays were luted with a dual resin composite and evaluated clinically using modified USPHS criteria at baseline, 8 months, 2, 3, 5, 6 and 8 yr, and indirectly using models. At baseline, 84% of the inlays were estimated as optimal and 16% as acceptable. Postoperative...

  17. An 8-year evaluation of sintered ceramic and glass ceramic inlays processed by the Cerec CAD/CAM system

    DEFF Research Database (Denmark)

    Pallesen, U.; Dijken van, J.W.V.

    2000-01-01

    of a glass ceramic (Dicor MGC) block. The inlays were luted with a dual resin composite and evaluated clinically using modified USPHS criteria at baseline, 8 months, 2, 3, 5, 6 and 8 yr, and indirectly using models. At baseline, 84% of the inlays were estimated as optimal and 16% as acceptable. Postoperative......The purpose of this study was to evaluate Cerec CAD/CAM inlays processed of two industrially made machinable ceramics during an 8-yr follow-up period. Each of 16 patients received two similar ceramic inlays. Half the number of the inlays were made of a feldspathic (Vita Mark II) and the other...... sensitivity was reported by one patient for 8 months. Of the 32 inlays evaluated during the 8 yr, 3 failed due to fracture of the material. No secondary caries was found adjacent to the inlays. No significant differences in the clinical performance were found between inlays made of the two ceramics. It can...

  18. No difference in the long-term clinical performance of direct and indirect inlay/onlay composite restorations in posterior teeth.

    Science.gov (United States)

    Dhadwal, Amardeep Singh; Hurst, Dominic

    2017-12-22

    Data sourcesMedline, Embase, the Cochrane Oral Health Group's Trials Register and CENTRAL. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. Hand searching of reference lists only.Study selectionRandomised controlled trials with a minimum of three years follow-up that compared direct to indirect inlays or onlays in posterior teeth. Primary outcome was failure (the need to replace or repair).Data extraction and synthesisTwo reviewers independently and in duplicate performed the study selection and two extracted data independently using a customised data extraction form. The unit of analysis was the restored tooth. Risk of bias was assessed using the Cochrane Risk of Bias tool. Meta-analysis was conducted on two studies using the random-effects model.ResultsThree studies were included. Across these studies there were 239 participants in whom 424 restorations were placed. Two studies compared direct and indirect inlays and had follow-up of five and 11 years respectively. One study compared direct and indirect onlays with a follow-up of five years. The studies were at unclear or high risk of bias. For direct and indirect inlays, Relative Risk (RR) of failure after five years was 1.54 (95% Cl: 0.42, 5.58; p = 0.52) in one study and, in another was 0.95 (95% Cl: 0.34, 2.63; p = 0.92) over 11 years. For onlays there was also no statistically-significant difference in survival, though overall five-year survival was 87% (95% CI: 81-93%).ConclusionsThere is insufficient evidence to favour the direct or indirect technique for the restoration of posterior teeth with inlays and onlays.

  19. Reharvested cranial particulate bone graft ossifies inlay calvarial defects.

    Science.gov (United States)

    Hassanein, Aladdin H; Couto, Rafael A; Mulliken, John B; Rogers, Gary F; Greene, Arin K

    2012-09-01

    Particulate bone graft (PBG) heals calvarial critical-size defects and is procured from the cranium with a hand-driven bit and brace. The donor sites ossify, and thus PBG potentially could be reharvested from the original areas. The purpose of this study was to determine if PBG obtained from a healed donor site is effective for inlay cranioplasty. A 17 × 17-mm critical-size defect was created in the parietal bones of 8 rabbits and treated with either no implant (group 1) or PBG harvested from the frontal bone (group 2). In 4 animals (group 3), a parietal defect was not created initially; PBG was harvested from the frontal bone and then discarded. Sixteen weeks later after the PBG donor sites had healed, a 17 × 17-mm parietal defect was made and filled with PBG reharvested from the previous donor area. Animals underwent micro-computed tomography 16 weeks after inlay cranioplasty. Critical-size defects in controls (group 1) exhibited partial ossification (35.1% ± 10.5%) compared with those treated with PBG (group 2) (99.1% ± 1.5%) or reharvested PBG (group 3) (99.3% ± 1.5%) (P = 0.02). No difference was found between groups 2 and 3 (P = 0.69). Bony thickness was similar in defects implanted with PBG (1.8 mm ± 1.1 mm) or reharvested PBG (2.1 mm ± 0.5 mm) (P = 0.68). Particulate bone graft reharvested from healed donor sites ossifies inlay cranial defects. Because the donor area for PBG is of partial thickness and less than critical size, reparative osteogenesis theoretically allows an unlimited supply of autologous bone for inlay cranioplasty using PBG.

  20. Ceramic inlays: a case presentation and lessons learned from the literature.

    Science.gov (United States)

    Boushell, Lee W; Ritter, André V

    2009-01-01

    Ceramic dental restorative materials offer an esthetic alternative to dental amalgam or gold. There is uncertainty relative to the longevity of ceramic inlay restorations. Recently published long-term research studies reveal general clinical performance trends. These trends are discussed while presenting a ceramic inlay case. Successful clinical use of ceramic inlay materials is absolutely dependent on the creation of an uncompromised adhesive tooth/ceramic interface. Ceramic inlay restorations perform well in terms of long-term retention, color match, and anatomic contour stability. These restorations all experience limited margin deterioration that does not predispose to marginal discoloration or secondary caries. Patients rarely suffer from postoperative sensitivity secondary to ceramic inlay placement. Ceramic inlays fail predominantly as a result of crack propagation from material flaws leading to bulk fracture. Some superficial ceramic defects may be repaired with composite resin. Internal material flaws are minimized by industrial production of indirect pressable glass-ceramic materials or ceramic blocks designed for computer-aided design/computer-assisted manufacturing (CAD/CAM). External surface flaws are limited by careful polishing techniques. Strategic placement of ceramic inlays in teeth that are not subject to heavy occlusal loading will result in more predictable long-term performance. Preparation design to prevent flexure of ceramic inlay materials is essential. Use of ceramic inlays to restore defects in posterior teeth requires careful attention to detail. Placement of ceramic inlay materials in high-stress areas may result in less predictable long-term performance. Ceramic inlays are advantageous for restoring moderately sized defects when optimal control of restoration contours and esthetics is desired.

  1. Fracture strength and bending of all-ceramic and fiber-reinforced composites in inlay-retained fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Serkan Saridag

    2012-06-01

    Conclusions: Zirconia-based ceramic inlay-retained fixed partial dentures demonstrated the highest fracture strength. The fiber-reinforced composite inlay-retained fixed partial dentures demonstrated higher bending values than did the all-ceramic inlay-retained fixed partial dentures.

  2. Human skulls with turquoise inlays: pre hispanic origin or replicas?

    International Nuclear Information System (INIS)

    Silva V, Y.; Castillo M, M.T.; Bautista M, J.P.; Arenas A, J.

    2006-01-01

    The lack of archaeological context determining if the manufacture of two human skulls adorned with turquoise inlays have pre-Columbian origin or not (replicas), led to perform other studies. Under these conditions, besides orthodox methodology commonly used to assign chronology and cultural aspects as form, style, decoration, iconography, etc., it was necessary to obtain more results based on the use of characterization techniques. The techniques employed were Scanning Electron Microscopy (SEM), X-Ray Energy Dispersive Spectroscopy (EDS), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), in order to determine the manufacture techniques and chemical composition of the materials used for the cementant. SEM analysis showed the presence of zones composed by Ca, O, C and Al. In some cases Mg, Cl, Fe and Pb were identified. High concentration of Cu was present in all samples, due to residues of turquoise inlays (CuAI 6 (PO 4 ) 4 (OH) 8 (H 2 O) 4 ) with which the skulls were decorated. In the cementant was identified the Ca as base element of the cementant, as well as particles < 100 nm with irregular morphology and other amorphous zones. FTIR spectrums indicated the presence of organic substances that could be used as agglutinating in the cementant. The current work shows a progress identifying involved techniques in the manufacturing of two human skulls with turquoise inlays. (Author)

  3. Dorsal inlay inner preputial graft for primary hypospadias repair

    Directory of Open Access Journals (Sweden)

    Rajendra B. Nerli

    2014-01-01

    Full Text Available Background: The most commonly performed operation to repair distal hypospadias is the Tubularised incised plate (TIP repair. The key step is midline incision of the urethral plate, which widens a narrow plate and converts a flat into a deep plate groove, ensuring a vertical, slit neomeatus and a normal-calibre neourethra. At times in cases of proximal hypospadias, the urethral plate is very narrow and needs to be augmented or substituted for further tubularisation. We report our experience with primary single stage dorsal inlay urethroplasty using preputial skin grafts. Patients and Methods: Children with proximal hypospadias with a narrow urethral plate formed the study group. Children needing transection of the urethral plate, having undergone circumcision/hypospadias repair previously or having an inadequate prepuce was excluded. Results: Twelve children with a mean age of 48.83 months underwent primary dorsal inlay preputial graft urethroplasty for proximal hypospadias with a very narrow urethral plate. At an average follow-up of 42.16 months, 2 (16.66% children had a breakdown of ventral shaft skin. None of the children had meatal stenosis, and none of these 12 children developed urethrocutaneous fistula. Conclusion: Primary dorsal inlay inner preputial graft urethroplasty successfully fulfills all traditional hypospadias repair criteria. It offers a viable, safe, rapid and easy option in the management of proximal hypospadias with a narrow urethral plate.

  4. Investigating inlay permeability by means of labelled atoms

    International Nuclear Information System (INIS)

    Rajchev, L.; Chakmakov, D.

    1979-01-01

    An isotope method was used in the study of marginal space permeability (space between cavity walls and obturation) and its relation to the qualities of cementing material. To this end, V class cavities were elaborated and microdentures preprared under unified conditions for recently extracted intact human teeth. The inlays were adjusted by being riveted at first and then cemented. Microdentures were fixed with ''Adhesor'' phosphate cement, zinc-eugenol paste or adhesive wax, applied upon the phase and part of the cavity wall. Twenty four hours later the teeth were covered with wax. The inlay and a strip around it remained uncovered and immersed in iodine 125 solution of sulphur 35-methionine. The teeth were then washed and incorporated in epoxide resin. Longitudinal incisions were made through the inlay and, after appropriate processing, autoradiography of the sections was made. The marginal space was shown to be permeable in a different degree, depending on the fixing material: whereas wax gluing makes it impermeable for either isotope, gluing with zinc-eugenol paste allows minor permeability for sulphur 35 and a rather high one for iodine 125. With phosphate cement gluing, iodine 125 reaches the cavity bottom, while penetration of sulphur 35 is rather limited. (A.B.)

  5. Preparation of alumina microspheres

    International Nuclear Information System (INIS)

    Santos, W.R. dos; Abrao, A.

    1980-01-01

    Inorganic exchangers are widely used for adsorption and column partition chromatography. The main difficulty of using commercial alumina (in powder) for column chromatography is related to its packing, and the operations through the column become diffcult and time-consuming; also it turns to be virtually impossible to use large dimension columns. In order to eliminate these problems, a process for the preparation of alumina micro-spheres was developed as an adaptation of a similar process used to prepare nuclear fuel microspheres (UO 2 , ThO 2 ). The flowsheet of this process is presented together with the analytical results of sphericity after calcination, granulometry, density and characterization by X-ray diffractometry. Solubility tests showed that the so-prepared microspheres are well resistant to strong acids and bases; retention tests showed their efficiency, mainly to copper. (C.L.B.) [pt

  6. Influence of immediate dentin sealing techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays.

    Science.gov (United States)

    Oliveira, L; Mota, E G; Borges, G A; Burnett, L H; Spohr, A M

    2014-01-01

    SUMMARY This research evaluated the influence of immediate dentin sealing (IDS) techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays. Forty-eight maxillary premolars were divided into four groups: G1, sound teeth (control); G2, without IDS; G3, IDS with Clearfil SE Bond (CSE); and G4, IDS with CSE and Protect Liner F. The teeth from groups 2, 3, and 4 received mesio-distal-occlusal preparations. The impressions were made with vinyl polysiloxane, followed by provisional restoration and storage in water for seven days. The impressions were poured using type IV die stone, and inlays with Filtek Z250 composite resin were built over each cast. The inlays were luted with Panavia F. After storage in water for 72 hours, a 200-N load was applied on the occlusal surface using a metal sphere connected to a universal testing machine, and the cuspal deflection was measured with a micrometer. The specimens were then submitted to an axial load until failure. The following mean cuspal deflection (μm) and mean fracture resistance (N) followed by the same lowercase letter represent no statistical difference by analysis of variance and Tukey (p<0.05): cuspal deflection: G1, 3.1 ± 1.5(a); G2, 10.3 ± 4.6(b); G3, 5.5 ± 1.8(ac); and G4, 7.7 ± 5.1(bc); fracture resistance: G1, 1974 ± 708(a); G2, 1162 ± 474(b); G3, 700 ± 280(b); and G4, 810 ± 343(b). IDS with CSE allowed cuspal deflection comparable with that associated with sound teeth. The application of Protect Liner F did not contribute to a decrease in cuspal deflection. The IDS techniques did not influence the fracture resistance of teeth.

  7. Uranyl sorption onto alumina

    International Nuclear Information System (INIS)

    Jacobsson, A.M.M.

    1997-01-01

    The mechanism for the adsorption of uranyl onto alumina from aqueous solution was studied experimentally and the data were modeled using a triple layer surface complexation model. The experiments were carried out at low uranium concentrations (9 x 10 -11 --5 x 10 -8 M) in a CO 2 free environment at varying electrolyte concentrations (0.01--1 M) and pH (4.5--12). The first and second acid dissociation constants, pK a1 and pK a2 , of the alumina surface were determined from potentiometric titrations to be 7.2 ± 0.6 and 11.2 ± 0.4, respectively. The adsorption of uranium was found to be independent of the electrolyte concentration. The authors therefore conclude that the uranium binds as an inner sphere complex. The results were modeled using the code FITEQL. Two reactions of uranium with the surface were needed to fit the data, one forming a uranyl complex with a single surface hydroxyl and the other forming a bridged or bidentate complex reacting with two surface hydroxyls of the alumina. There was no evidence from these experiments of site heterogeneity. The constants used for the reactions were based in part on predictions made utilizing the Hard Soft Acid Base, HSAB, theory, relating the surface complexation constants to the hydrolysis of the sorbing metal ion and the acid dissociation constants of the mineral oxide surface

  8. Fracture resistance of direct inlay-retained adhesive bridges : Effect of pontic material and occlusal morphology

    NARCIS (Netherlands)

    Breuklander, Marijn; Salihoglu-Yener, Esra; Ozcan, Mutlu

    This study evaluated the effect of a) pontic materials and b) occlusal morphologies on the fracture resistance of fiber-reinforced composite (FRC) inlay-retained fixed dental prostheses (FDP). Inlay-retained FRC FPDs (N=45, n=9) were constructed using a) resin composite (deep anatomy), b) natural

  9. Effects of metal-inlay thickness in polyethylene cups with metal-on-metal bearings.

    NARCIS (Netherlands)

    Verdonschot, N.J.J.; Vena, P.; Stolk, J.; Huiskes, R.

    2002-01-01

    A way to prevent polyethylene wear in total hip replacements is to use metal-on-metal bearings. The cup design of these bearings may be a metal inlay in a polyethylene cup. However, these metal inlays are relatively thin and may deform on loading. The purpose of the current study was to determine

  10. In vivo and in vitro evaluation of marginal fit of class II ceromer inlays.

    Science.gov (United States)

    Gemalmaz, D; Kükrer, D

    2006-06-01

    The aim of this study was to evaluate the marginal adaptation of class II ceromer (Targis, Vivadent) indirect inlay restorations under both in vivo and in vitro conditions. Twenty Targis inlays were produced for class II inlay cavities (13 mandibular and seven maxillary teeth) in 20 patients. The in vivo adaptation of the inlay to the tooth cavity was evaluated by means of silicone replica technique. For in vitro evaluation, 20 mesio-occluso-distal (MOD) Targis inlays were made in extracted upper molars. Half of the inlays were cemented with Variolink high-viscosity resin cement while the other half was cemented with Variolink Ultra. The replica specimens and in vitro samples were sectioned buccolingually and mesiodistally, and marginal adaptation was evaluated at both proximal and occlusal margins at 200x magnification under a light microscope. The data was analyzed with anova (P < 0.05). The in vivo mean film thickness values for occlusal and proximal locations were recorded as 73 and 132 microm respectively. In vitro mean marginal fit values were observed as 48 and 67 microm for occlusal and proximal margins of inlays luted with Variolink II high viscosity. The marginal fit values recorded under in vivo conditions were higher in magnitude than the measurements obtained under in vitro conditions. The use of a highly filled resin luting agent with an ultrasonic insertion technique did not cause an increase in marginal gap width of the inlay.

  11. Significance of structure–property relationship in alumina based ...

    Indian Academy of Sciences (India)

    Unknown

    plimented by drastic reduction in failure and quality pro- blems experienced by insulator manufacturers (Lieberman). However, even alumina insulators manufactured (for use in 25 kV railway traction lines) under stringent ..... early showed plastic deformation and large cracks in and around the indents. Figure 7c shows the ...

  12. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique.

    Science.gov (United States)

    Ayse Gozde, Turk; Metin, Sabuncu; Mubin, Ulusoy

    2018-02-01

    Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

  13. Comparison of Microleakage and Thickness of Resin Cement in Ceramic Inlays with Various Temperatures

    Science.gov (United States)

    Alaghemand, Homayoun; Abolghasemzadeh, Faezeh; Pakdel, Farzaneh; Judi Chelan, Reza

    2014-01-01

    Background and aims. Microleakage is still one of the major problems of composite-based restorations.This study compared the microleakage and thickness of resin cement in ceramic inlays with various temperatures. Materials and methods. Class V cavities were prepared on the buccal and lingual aspects of thirty human molars with occlusal margins in enamel and gingival margins in dentin (3 mm wide, 5 mm long and 2 mm deep). Laboratory-made inlays (LMI) were used for buccal cavities, and CAD/CAM inlays (CMI) were used for lingual cavities. All the cavities were divided into six groups (n=10): 1) LMI at -5°C; 2) LMI at 50°C; 3) LMI at room temperature (25°C); 4) CMI at -5°C; 5) CMI at 50°C; 6) CMI at room temperature (25°C). Inlays were bonded to cavities in a pulp pressure- and temperature-simulating device. After thermocycling and dye penetration, the teeth were divided into two mesiodistal halves. Amount of dye penetration and film thickness were measured under a stereomicroscope and analyzed with Kruskal-Wallis, Wilcoxon and Spearman's correlation tests ( = 0.05). Results. There were no statistically significant differences in leakage between different inlay temperatures (P > 0.05). The mean cement thickness in laboratory-made inlays (gingival margin, 83.7 ± 11 and occlusal margin, 84.7 ± 19) was greater than that in CAD/CAM inlays (gingival margin, 69 ± 16 and occlusal margin, 84.7 ± 16). No correlation was found be-tween cement thickness and microleakage either in enamel or dentin for any of the ceramic systems. Conclusion. Differences in inlay temperature had no effect on microleakage. CAD/CAM inlays had lower cement thickness than laboratory-made inlays, but this was not related to their microleakage. PMID:25024839

  14. Comparison of Microleakage and Thickness of Resin Cement in Ceramic Inlays with Various Temperatures

    Directory of Open Access Journals (Sweden)

    Homayoun Alaghemand

    2014-03-01

    Full Text Available Background and aims. Microleakage is still one of the major problems of composite-based restorations. This study compared the microleakage and thickness of resin cement in ceramic inlays with various temperatures. Materials and methods. Class V cavities were prepared on the buccal and lingual aspects of thirty human molars with occlusal margins in enamel and gingival margins in dentin (3 mm wide, 5 mm long and 2 mm deep. Laboratory-made inlays (LMI were used for buccal cavities, and CAD/CAM inlays (CMI were used for lingual cavities. All the cavities were divided into six groups (n=10: 1 LMI at -5°C; 2 LMI at 50°C; 3 LMI at room temperature (25°C; 4 CMI at -5°C; 5 CMI at 50°C; 6 CMI at room temperature (25°C. Inlays were bonded to cavities in a pulp pressure- and temperaturesimulating device. After thermocycling and dye penetration, the teeth were divided into two mesiodistal halves. Amount of dye penetration and film thickness were measured under a stereomicroscope and analyzed with Kruskal-Wallis, Wilcoxon and Spearman's correlation tests ( = 0.05. Results. There were no statistically significant differences in leakage between different inlay temperatures (P > 0.05. The mean cement thickness in laboratory-made inlays (gingival margin, 83.7 ± 11 and occlusal margin, 84.7 ± 19 was greater than that in CAD/CAM inlays (gingival margin, 69 ± 16 and occlusal margin, 84.7 ± 16. No correlation was found between cement thickness and microleakage either in enamel or dentin for any of the ceramic systems. Conclusion. Differences in inlay temperature had no effect on microleakage. CAD/CAM inlays had lower cement thickness than laboratory-made inlays, but this was not related to their microleakage.

  15. Shockless spalling damage of alumina ceramic

    Science.gov (United States)

    Erzar, B.; Buzaud, E.

    2012-05-01

    Ceramic materials are commonly used to build multi-layer armour. However reliable test data is needed to identify correctly models and to be able to perform accurate numerical simulation of the dynamic response of armour systems. In this work, isentropic loading waves have been applied to alumina samples to induce spalling damage. The technique employed allows assessing carefully the strain-rate at failure and the dynamic strength. Moreover, specimens have been recovered and analysed using SEM. In a damaged but unbroken specimen, interactions between cracks has been highlighted illustrating the fragmentation process.

  16. Bauxite Mining and Alumina Refining

    Science.gov (United States)

    Frisch, Neale; Olney, David

    2014-01-01

    Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. Conclusions: A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures. PMID:24806720

  17. Influence of different curing approaches on marginal adaptation of ceramic inlays.

    Science.gov (United States)

    Rechenberg, Dan-Krister; Göhring, Till N; Attin, Thomas

    2010-06-01

    To evaluate the effect of different curing protocols on marginal adaptation of ceramic inlays after thermomechanical loading (TML). Forty-eight human molars were randomly divided into 6 groups (n = 8). After Class II cavity preparation (mod), ceramic inlays (Cerec) were fabricated. In groups I to IV, the cavities were conditioned with XP Bond mixed with Self Cure Activator (SCA) and the inlays were placed with the luting composite (LC) Calibra Mix (dual curing). The teeth in groups V and VI were conditioned with XP Bond without SCA and the inlays were placed with Calibra base (only light curing). In groups III, IV and V the adhesive was separately light cured prior to, and in groups II, IV, V and VI, after the inlay insertion. Before and after TML, marginal adaptation was measured using scanning electron microscopy (200X). Continuous margins (% of the total) were compared between groups using analysis of variance (ANOVA). A Bonferroni correction was applied to correct for multiple testing (alpha inlay insertion improved marginal adaptation on the occlusal interface between LC and enamel significantly, regardless of the LC's curing mode. Separate light polymerization of XP Bond did not result in superior marginal quality. Investigation of the interface between LC and proximal dentin margins showed improved adaptation by dual curing the adhesive and LC, irrespective of light application. Light curing after inlay insertion showed improved marginal adaptation. Using dual-curing adhesive and LC, advantages in marginal adaptation between LC and dentin were observed.

  18. Influence of proximal box elevation technique on marginal integrity of adhesively luted Cerec inlays.

    Science.gov (United States)

    Müller, Veronika; Friedl, Karl-Heinz; Friedl, Katrin; Hahnel, Sebastian; Handel, Gerhard; Lang, Reinhold

    2017-03-01

    This in vitro study evaluated the marginal quality of Lava Ultimate inlays in deep proximal cavities with and without proximal box elevation (PBE) before and after thermomechanical loading (TML). Mesio-occluso-distal cavities with proximal boxes beneath the cementoenamel junction (CEJ) were prepared in 24 human molars. Then, one of the proximal boxes was elevated with Filtek Supreme above the CEJ. The specimens were divided into three groups (n = 8). The inlays of group A were adhesively luted to the cavities with Scotchbond Universal and Rely X Ultimate, the inlays of group B with Monobond Plus, Syntac, and Variolink II, and the inlays of group C with Clearfil Ceramic Primer and Panavia SA Cement. Epoxy resin replicas were taken before and after thermomechanical loading (1,200,000 cycles, 55 °C/5 °C, max. load 50 N). Marginal integrity at the different interfaces tooth/PBE, tooth/dentine, inlay/PBE, inlay/dentine was evaluated with scanning electron microscopy (×200). The percentage of continuous margin (% of total proximal margin length) was compared between the groups before and after TML. Mann-Whitney U test (p = 0.05). No significant differences (p > 0.05) before and after TML were found between the three groups for bonding the inlay to dentine or to PBE composite. The marginal integrities of bonding inlays directly to dentine are not different from bonding inlays to a proximal box, which has been elevated by a composite filling material. For deep proximal cavities, the PBE technique could be an alternative technique to conventional methods. Clinical research is needed to confirm.

  19. Vignetting and Field of View with the KAMRA Corneal Inlay

    Directory of Open Access Journals (Sweden)

    Achim Langenbucher

    2013-01-01

    Full Text Available Purpose. To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. Methods. A KAMRA inlay was “implanted” into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from −70° to 70° with and without KAMRA and proportion of light attenuation was recorded. Results. In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA. Conclusion. For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

  20. Vignetting and Field of View with the KAMRA Corneal Inlay

    Science.gov (United States)

    Goebels, Susanne; Szentmáry, Nóra; Seitz, Berthold

    2013-01-01

    Purpose. To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. Methods. A KAMRA inlay was “implanted” into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from −70° to 70° with and without KAMRA and proportion of light attenuation was recorded. Results. In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA. Conclusion. For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect. PMID:24324954

  1. Alumina-Reinforced Zirconia Composites

    Science.gov (United States)

    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.

  2. Geometric design method for occlusal outlines of complex class I and class II inlay cavities.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Takada, Yukyo

    2011-01-01

    The purpose of this study was to establish a geometric design method for the occlusal outlines of complex inlay cavities as a continuation study of a previous design method for simple class I inlay cavity. A method for extending the occlusal outline to the buccal or lingual groove and to three preparation types of the proximal portions of class II inlay cavities -namely, straight line preparation, sweeping curve preparation, and reverse curve preparation- was investigated. To ensure the smoothness of the occlusal outline, a Bézier curve was introduced in the design. A minimal number of control points for the curve was applied to define each preparation type. The design method was experimentally applied to mandibular and maxillary first molars. Smooth outlines of the complex inlay cavities in the molars with tool accessibility throughout the cavities were achievable by using the present method.

  3. ONLAY VS. INLAY MYRINGOPLASTY WITH TRAGAL PERICHONDRIUM- A HOSPITAL-BASED RETROSPECTIVE STUDY

    Directory of Open Access Journals (Sweden)

    Guha T

    2016-11-01

    Full Text Available BACKGROUND Myringoplasty is the surgical repair of tympanic membrane. Most commonly used techniques are onlay and inlay. Common graft materials include temporalis fascia and tragal perichondrium. MATERIALS AND METHODS In this present retrospective study involving 60 patients with 30 each in onlay and inlay group who underwent myringoplasty by transmeatal approach using tragal perichondrial graft. RESULTS We found success rate of 90% in onlay and 93.3% in inlay method, difference of which was not statistically significant. Degree of hearing improvement was 15.95 dB for onlay group and 16.48 in inlay group and the difference was again not significant. CONCLUSION The only advantage of onlay procedure was consumption of little less amount of time. Apart from that, we concluded that none of these methods are superior to other.

  4. Efficacy of composite versus ceramic inlays and onlays: study protocol for the CECOIA randomized controlled trial.

    Science.gov (United States)

    Fron Chabouis, Hélène; Prot, Caroline; Fonteneau, Cyrille; Nasr, Karim; Chabreron, Olivier; Cazier, Stéphane; Moussally, Christian; Gaucher, Alexandre; Khabthani Ben Jaballah, Inès; Boyer, Renaud; Leforestier, Jean-François; Caumont-Prim, Aurore; Chemla, Florence; Maman, Louis; Nabet, Cathy; Attal, Jean-Pierre

    2013-09-03

    Dental caries is a common disease and affects many adults worldwide. Inlay or onlay restoration is widely used to treat the resulting tooth substance loss. Two esthetic materials can be used to manufacture an inlay/onlay restoration of the tooth: ceramic or composite. Here, we present the protocol of a multicenter randomized controlled trial (RCT) comparing the clinical efficacy of both materials for tooth restoration. Other objectives are analysis of overall quality, wear, restoration survival and prognosis. The CEramic and COmposite Inlays Assessment (CECOIA) trial is an open-label, parallel-group, multicenter RCT involving two hospitals and five private practices. In all, 400 patients will be included. Inclusion criteria are adults who need an inlay/onlay restoration for one tooth (that can be isolated with use of a dental dam and has at least one intact cusp), can tolerate restorative procedures and do not have severe bruxism, periodontal or carious disease or poor oral hygiene. The decayed tissue will be evicted, the cavity will be prepared for receiving an inlay/onlay and the patient will be randomized by use of a centralized web-based interface to receive: 1) a ceramic or 2) composite inlay or onlay. Treatment allocation will be balanced (1:1). The inlay/onlay will be adhesively luted. Follow-up will be for 2 years and may be extended; two independent examiners will perform the evaluations. The primary outcome measure will be the score obtained with use of the consensus instrument of the Fédération Dentaire Internationale (FDI) World Dental Federation. Secondary outcomes include this instrument's items, inlay/onlay wear, overall quality and survival of the inlay/onlay. Data will be analyzed by a statistician blinded to treatments and an adjusted ordinal logistic regression model will be used to compare the efficacy of both materials. For clinicians, the CECOIA trial results may help with evidence-based recommendations concerning the choice of materials for

  5. A Modified Design for Posterior Inlay-Retained Fixed Dental Prosthesis

    OpenAIRE

    Samran, Abdulaziz; Nassani, Mohammad Zakaria; Aswad, Marwan; Abdulkarim, Amid

    2015-01-01

    The aim of this paper is to report a clinical case with bilateral missing mandibular second premolars that were restored by metal-ceramic inlay-retained fixed dental prostheses. The first prosthesis was of a traditional design and the second was of a modified design. The suggested design is created by modifying the retainer wings of the traditional resin-bonded inlay-retained fixed dental prosthesis and covering the wings with composite resin. The modified design is relatively conservative, e...

  6. Implantable inlay devices for presbyopia: the evidence to date

    OpenAIRE

    Arlt EM; Krall EM; Moussa S; Grabner G; Dexl AK

    2015-01-01

    EM Arlt, EM Krall, S Moussa, G Grabner, AK DexlDepartment of Ophthalmology, Paracelsus Medical University Salzburg, Salzburg, Austria Abstract: By 2020, it is estimated that 2.1 billion people will be presbyopic, and the demand for spectacle independence in this group is growing. This review article provides an overview of the three commercially available corneal inlays for the correction of presbyopia. Safety, efficacy, visual outcomes, and complications are analyzed for all three inlays acc...

  7. The all-ceramic, inlay supported fixed partial denture. Part 4. Fracture surface analyses of an experimental model, all-ceramic, inlay supported fixed partial denture.

    Science.gov (United States)

    Thompson, M C; Sornsuwan, T; Swain, M V

    2013-06-01

    In the previous three papers, the authors sought to conduct a thorough analysis of the feasibility for the use of zirconia in inlay supported, fixed partial dentures via finite element analysis (FEA). Correlating the response of the numerical model against the experimental model has never been satisfactorily performed for an anatomically accurate ceramic bridge; such validation is crucial if the results from the FEA are to be confidently relied upon. Part 4 of this series is a detailed fractographic analysis of the zirconia bridge that was the model for the experimental validation, performed in order to confirm the fracture origin/s and fracture trajectory as predicted from the FEA. Established fractographic techniques involving optical examination followed by examination with scanning electron microscopy were conducted. The porous, granular surface of zirconia (both partially and fully sintered) does not lend itself to easy surface analysis but the classic fractographic signs (hackle lines, wake hackle lines and compression curl) are present. Use of linear fracture elastic mechanics allowed the calculation of theoretical critical flaw size and a comparison to two defects or inclusions found at the primary origin of fracture. Excellent agreement between the fracture sites and paths of travel as predicted in the numerical analysis exist with fractographic analysis. Furthermore, the calculated critical flaw size of 30 μm to 40 μm equates very well with defects seen at the general vicinity of the primary fracture origin and the general observed size of critical flaws in machined ceramics which range between 20 μm to 50 μm, thus providing further confirmation. The fractographic analysis detailed in this study provides validation of the 'zones of failure' as predicted in our FEA. Additionally, the excellent correlation between the calculated critical flaw size and the defects observed at the primary fracture site demonstrates that field of experimental mechanics is

  8. Power density of various light curing units through resin inlays with modified layer thickness

    Science.gov (United States)

    Hong, Sung-Ok; Oh, Yonghui; Min, Jeong-Bum; Kim, Jin-Woo; Lee, Bin-Na; Hwang, Yun-Chan; Hwang, In-Nam; Oh, Won-Mann

    2012-01-01

    Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays. PMID:23431061

  9. A systematic review of ceramic inlays in posterior teeth: an update.

    Science.gov (United States)

    Pol, Christiaan W P; Kalk, Warner

    2011-01-01

    Ceramic materials, first introduced in restorative dentistry in the late 18th century, offer a wide range of possibilities and exhibit esthetic properties. The last systematic reviews on the subject of ceramic inlays were published in 2003. All articles published up to 2001 were surveyed regarding the longevity, esthetic qualities, and postoperative discomfort associated with the use of ceramic inlays compared to other restorative materials. The present review aimed to establish the current state of the art. Using methods identical to those of previous reviews, the literature from 2001 up to and including 2009 was assessed. The scientific and methodologic qualities of all articles describing the use of ceramic inlays were established. Articles comparing the results of ceramic inlays to other types of inlays were then used to answer the hypotheses that there were no differences in longevity, postoperative sensitivity, or color match. Three articles comparing the results of ceramic to other materials were analyzed further. No new reliable evidence was found to update the answer to the hypothesis that there was no difference in longevity, at least in the first year postoperative. The evidence found regarding postoperative discomfort backs the previous conclusion that there was no difference. New evidence found on color matching suggests that there is no significant difference in color match over assessment periods of up to 57 months. Current ceramic materials in inlay restorations seem to perform as well as other restorative options for selected properties during the first years after placement.

  10. Alumina strength degradation in the elastic regime

    International Nuclear Information System (INIS)

    Furnish, Michael D.; Chhabildas, Lalit C.

    1998-01-01

    Measurements of Kanel et al. [1991] have suggested that deviatoric stresses in glasses shocked to nearly the Hugoniot Elastic Limit (HEL) relax over a time span of microseconds after initial loading. 'Failure' (damage) waves have been inferred on the basis of these measurements using time-resolved manganin normal and transverse stress gauges. Additional experiments on glass by other researchers, using time-resolved gauges, high-speed photography and spall strength determinations have also lead to the same conclusions. In the present study we have conducted transmitted-wave experiments on high-quality Coors AD995 alumina shocked to roughly 5 and 7 GPa (just below or at the HEL). The material is subsequently reshocked to just above its elastic limit. Results of these experiments do show some evidence of strength degradation in the elastic regime

  11. Alumina Yield in the Bayer Process

    Science.gov (United States)

    Den Hond, R.

    The alumina industry has historically been able to reduce alumina production costs, by increasing the liquor alumina yield. To know the potential for further yield increases, the phase diagram of the ternary system Na2O-Al2O -H2O at various temperature levels was analysed. It was found that the maximum theorical precipitation alumina yield is 160 g/l, while that for digestion was calculated to be 675 g/l.

  12. Fracture resistance of teeth restored with all-ceramic inlays and onlays: an in vitro study.

    Science.gov (United States)

    Saridag, S; Sevimay, M; Pekkan, G

    2013-01-01

    Fracture resistance of inlays and onlays may be influenced by the quantity of the dental structure removed and the restorative materials used. The purpose of this in vitro study was to evaluate the effects of two different cavity preparation designs and all-ceramic restorative materials on the fracture resistance of the tooth-restoration complex. Fifty mandibular third molar teeth were randomly divided into the following five groups: group 1: intact teeth (control); group 2: inlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press, Ivoclar Vivadent AG, Schaan, Liechtenstein); group 3: inlay preparations, zirconia ceramic (ICE Zirkon, Zirkonzahn SRL, Gais, Italy); group 4: onlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press); and group 5: onlay preparations, zirconia ceramic (ICE Zirkon). The inlay and onlay restorations were adhesively cemented with dual polymerizing resin cement (Variolink II, Ivoclar Vivadent AG). After thermal cycling (5° to 55°C × 5000 cycles), specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. Statistical analyses were performed using one-way analysis of variance and Tukey HSD tests. The fracture strength values were significantly higher in the inlay group (2646.7 ± 360.4) restored with lithium-disilicate glass-ceramic than those of the onlay group (1673.6 ± 677) restored with lithium-disilicate glass-ceramic. The fracture strength values of teeth restored with inlays using zirconia ceramic (2849 ± 328) and onlays with zirconia ceramic (2796.3 ± 337.3) were similar to those of the intact teeth (2905.3 ± 398.8). In the IPS e.max Press groups, as the preparation amount was increased (from inlay to onlay preparation), the fracture resistance was decreased. In the ICE Zirkon ceramic groups, the preparation type did not affect the fracture resistance results.

  13. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ayşe Gözde TÜRK

    Full Text Available ABSTRACT Objective The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Material and Methods Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs, allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply, and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (p<0.05, before and after cementation. Results Direct inlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442 and after (p=0.00001466 cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively. The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Conclusions Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after

  14. Marginal Adaptation of Indirect Composite, Glass-Ceramic Inlays and Direct Composite: An In Vitro Evaluation

    Directory of Open Access Journals (Sweden)

    F. Mahboub

    2010-06-01

    Full Text Available Objective: This experimental in vitro study compared marginal adaptation of indirect composite, glass-ceramic inlays and direct composite.Materials and Methods: Seventy-five recently extracted human molars were randomly divided into three groups (n=25 and mesio-occluso-distal cavities with the same dimensions were prepared in the teeth. Indirect composite and glass-ceramic inlays were fabricatedfollowing manufacturer's instructions and the marginal gap was measured by a stereomicroscope at magnification 40× before cementation. After cementation of inlays and restoring the third group by direct composite, all the specimens were thermocycled and the marginal gaps were measured exactly as previously described. Repeated measure ANOVA and post-hoc Tukey test were used for pairwise comparison of occlusal, proximal, and gingival marginal gaps in each group. One-way ANOVA and post-hoc Tukey test wereused for comparison of mean marginal gap in the three groups and for comparison of marginal gap before and after cementation in inlays, paired T-test was used.Results: The marginal gap of direct composite (19.96 μm was significantly lower than that of indirect composite inlay (48.47 μm, which in itself was significantly lower than that of glass-ceramic inlay (60.96 μm. In all the restorations, marginal gap in the gingival margin was significantly higher than occlusal and proximal margins. The marginal gap of inlays did not change after cementation and thermocycling.Conclusion: This study indicated that the marginal gaps of the evaluated restorations are less than 100 μm, which is clinically acceptable.

  15. Marginal Adaptation of Indirect Composite, Glass-Ceramic Inlays and Direct Composite: An In Vitro Evaluation

    Science.gov (United States)

    Zarrati, S.; Mahboub, F.

    2010-01-01

    Objective: This experimental in vitro study compared marginal adaptation of indirect composite, glass-ceramic inlays and direct composite. Materials and Methods: Seventy-five recently extracted human molars were randomly divided into three groups (n=25) and mesio-occluso-distal cavities with the same dimensions were prepared in the teeth. Indirect composite and glass-ceramic inlays were fabricated following manufacturer’s instructions and the marginal gap was measured by a stereomicroscope at magnification 40× before cementation. After cementation of inlays and restoring the third group by direct composite, all the specimens were thermocycled and the marginal gaps were measured exactly as previously described. Repeated measure ANOVA and post-hoc Tukey test were used for pairwise comparison of occlusal, proximal, and gingival marginal gaps in each group. One-way ANOVA and post-hoc Tukey test were used for comparison of mean marginal gap in the three groups and for comparison of marginal gap before and after cementation in inlays, paired T-test was used. Results: The marginal gap of direct composite (19.96 μm) was significantly lower than that of indirect composite inlay (48.47 μm), which in itself was significantly lower than that of glass-ceramic inlay (60.96 μm). In all the restorations, marginal gap in the gingival margin was significantly higher than occlusal and proximal margins. The marginal gap of inlays did not change after cementation and thermocycling. Conclusion: This study indicated that the marginal gaps of the evaluated restorations are less than 100 μm, which is clinically acceptable. PMID:21998779

  16. Effect of the Femtosecond Laser on an Intracorneal Inlay for Surgical Compensation of Presbyopia during Cataract Surgery: Scanning Electron Microscope Imaging.

    Science.gov (United States)

    Ibarz, Marta; Rodríguez-Prats, Jose Luis; Hernández-Verdejo, Jose Luis; Tañá, Pedro

    2017-02-01

    To investigate the effect of the femtosecond laser-assisted cataract surgery (FLACS) on porcine eyes implanted with a Kamra corneal inlay and to describe how the inlay may change the effect of the femtosecond laser on the lens. FLACS was performed on six porcine eyes and a Kamra corneal inlay had been implanted, exploring the lens under the surgical microscope. Another Kamra corneal inlay was attached to the upper part of the transparent hemisphere used for calibration of the femtosecond laser. Capsulorhexis, arcuate incisions, and phacofragmentation were carried out. The Kamra corneal inlay was compared with a nontreated one using a scanning electron microscope (SEM), and the hemisphere was analyzed with a surgical microscope. Capsulorhexis and phacofragmentation were completed in all the porcine eyes, although accuracy to determine the exact effect on the lens was not possible to achieve. The effect of the femtosecond laser on the PMMA hemisphere through the Kamra corneal inlay showed the capsulorhexis was placed outside the outer margin of the inlay and a sharply sculpted fragmentation pattern with a three-dimensional (donut-shaped) annulus untreated beneath it. SEM images of the nontreated and the treated inlays were comparable. No ultrastructural changes were found in the treated Kamra corneal inlay. FLACS can be performed with a Kamra corneal inlay for surgical compensation of presbyopia without the risk of damaging the inlay. The Kamra corneal inlay acts as a screen that avoids the laser to reach the areas beneath its shadow, but not the exposed areas of the lens.

  17. Attrition resistant gamma-alumina catalyst support

    Science.gov (United States)

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2006-03-14

    A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

  18. Sintering behaviour of spinel–alumina composites

    Indian Academy of Sciences (India)

    % alumina dissolves in spinel (MgAl2O4) at 1600°C. Solid solubility of alumina in spinel decreases rapidly with decreasing temperature, which causes exsolution of alumina from spinel phase. Previous work of one of the authors revealed that ...

  19. Sintering behaviour of spinel–alumina composites

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Study of alumina–magnesia binary phase diagram reveals that around 40–50 wt% alumina dis- solves in spinel (MgAl2O4) at 1600°C. Solid solubility of alumina in spinel decreases rapidly with decreasing temperature, which causes exsolution of alumina from spinel phase. Previous work of one of the authors.

  20. Dynamic tensile response of alumina-Al composites

    International Nuclear Information System (INIS)

    Atisivan, R.; Bandyopadhyay, A.; Gupta, Y. M.

    2002-01-01

    Plate impact experiments were carried out to examine the high strain-rate tensile response of alumina-aluminum (Al) composites with tailored microstructures. A novel processing technique was used to fabricate interpenetrating phase alumina-aluminum composites with controlled microstructures. Fused deposition modeling (FDM), a commercially available rapid prototyping technique, was used to produce the controlled porosity mullite ceramic preforms. Alumina-Al composites were then processed via reactive metal infiltration of porous mullite ceramics. With this approach, both the micro as well as the macro structures can be designed via computer aided design (CAD) to tailor the properties of the composites. Two sets of dynamic tensile experiments were performed. In the first, the metal content was varied between 23 and 39 wt. percent. In the second, the microstructure was varied while holding the metal content nearly constant. Samples with higher metal content, as expected, displayed better spall resistance. For a given metal content, samples with finer metal diameter showed better spall resistance. Relationship of the microstructural parameters on the dynamic tensile response of the structured composites is discussed here

  1. Transport properties of alumina nanofluids

    International Nuclear Information System (INIS)

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-01-01

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 deg. C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m -1 K -1 was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 deg. C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at various

  2. Transport properties of alumina nanofluids.

    Science.gov (United States)

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 °C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m(-1) K(-1) was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 °C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at

  3. Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.

    Science.gov (United States)

    Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

    2012-01-06

    The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Residual Stress Evaluation of Weld Inlay Process on Reactor Vessel Nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Kihyun; Cho, Hong Seok [KEPCO KPS, Naju (Korea, Republic of)

    2015-10-15

    Weld overlay, weld inlay and stress improvement are mitigation technologies for butt joints. Weld overlay is done on pressurizer nozzles which are the highest potential locations occurring PWSCC due to high temperature in Korea. Reactor vessel nozzles are other big safety concerns for butt joints. Weld overlay and stress improvement should be so difficult to apply to those locations because space is too limited. Weld inlay should be one of the solutions. KEPCO KPS has developed laser welding system and process for reactor nozzles. Welding residual stress analysis is necessary for flaw evaluation. United States nuclear regulatory commission has calculated GTAW(Gas Tungsten Arc Welding) residual stress using ABAQUS. To confirm effectiveness of weld inlay process, welding residual stress analysis was performed. and difference between GTAW and LASER welding process was compared. Evaluation of weld inlay process using ANSYS and ABAQUS is performed. All of the both results are similar. The residual stress generated after weld inlay was on range of 450-500 MPa. Welding residual stresses are differently generated by GTAW and LASER welding. But regardless of welding process type, residual tensile stress is generated on inside surface.

  5. Residual Stress Evaluation of Weld Inlay Process on Reactor Vessel Nozzles

    International Nuclear Information System (INIS)

    Cho, Kihyun; Cho, Hong Seok

    2015-01-01

    Weld overlay, weld inlay and stress improvement are mitigation technologies for butt joints. Weld overlay is done on pressurizer nozzles which are the highest potential locations occurring PWSCC due to high temperature in Korea. Reactor vessel nozzles are other big safety concerns for butt joints. Weld overlay and stress improvement should be so difficult to apply to those locations because space is too limited. Weld inlay should be one of the solutions. KEPCO KPS has developed laser welding system and process for reactor nozzles. Welding residual stress analysis is necessary for flaw evaluation. United States nuclear regulatory commission has calculated GTAW(Gas Tungsten Arc Welding) residual stress using ABAQUS. To confirm effectiveness of weld inlay process, welding residual stress analysis was performed. and difference between GTAW and LASER welding process was compared. Evaluation of weld inlay process using ANSYS and ABAQUS is performed. All of the both results are similar. The residual stress generated after weld inlay was on range of 450-500 MPa. Welding residual stresses are differently generated by GTAW and LASER welding. But regardless of welding process type, residual tensile stress is generated on inside surface

  6. Influence of proximal box elevation on bond strength of composite inlays.

    Science.gov (United States)

    Da Silva Gonçalves, Dayana; Cura, María; Ceballos, Laura; Fuentes, Mª Victoria

    2017-01-01

    The objective of the present study was to evaluate the influence of proximal box elevation on microtensile bond strength (mTBS) of composite inlays to the proximal box floor, using either a total-etch or a self-adhesive resin cement. Twenty-five human molars were selected, and a class II OM (inlay) cavity preparation was performed in each tooth. Cavities were randomly assigned into four experimental groups, according to the location of the proximal cervical margin (located 1 mm below cementoenamel junction (CEJ), or with proximal box elevation with composite resin) and the resin cement used for luting (a total-etch resin cement RelyX ARC or a self-adhesive resin cement G-Cem). After 1-week water storage, samples were subjected to mTBS test. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p inlays for both resin cements. However, only for G-Cem was this improvement statistically significant. The proximal box elevation improved the bond strength attained by G-Cem resin cement. For RelyX ARC, the position of the cervical margin did not affect composite inlays bond strength. Proximal box elevation does not decline bond strength of composite inlays to the proximal floor when a total-etch or a self-adhesive resin cement is used.

  7. Four-year clinical evaluation of a self-adhesive luting agent for ceramic inlays.

    Science.gov (United States)

    Peumans, Marleen; Voet, M; De Munck, J; Van Landuyt, K; Van Ende, A; Van Meerbeek, B

    2013-04-01

    The aim of this randomized controlled clinical trial was to evaluate the 4-year clinical performance of a self-adhesive resin cement, RelyX Unicem (3M ESPE), used for cementation of ceramic inlays. In addition, the influence of selectively acid-etching enamel prior to luting on the clinical performance of the restorations was assessed. Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group: E) or without (=control group: NE) prior enamel etching with phosphoric acid. At baseline, 6 months, and 1, 2, and 4 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. Ten selected samples of each group were investigated under SEM regarding morphological changes at the cement-inlay interface. The recall rate at 4 years was 97%. Two restorations (1 E, 1 NE) were lost, and one (E) had to be replaced due to inlay and tooth fracture resulting in a survival rate of 95%. No significant differences between the experimental and control group were noticed regarding all criteria (McNemar, p inlays/onlays. Additional selective enamel etching does not improve the clinical performance of the restorations within the 4-year period. The self-adhesive resin composite RelyX Unicem showed acceptable clinical performance after 4 years of clinical service.

  8. Alumina column Rb-82 generator

    International Nuclear Information System (INIS)

    Yano, Y.; Roth, E.P.

    1977-10-01

    The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec 82 Rb was evaluated in both batches and column experiments using 85 Sr and cyclotron-produced 82 Sr. Comparisons of alumina, Bio-Rex 70 and Chelex 100 ion exchangers were made to determine Sr adsorption, 82 Rb elution yield and Sr breakthrough. The adsorption of Sr is similar for alumina and Chelex 100 but different for Bio-Rex 70. Alumina and Chelex 100 exhibit a small fraction of poorly bound Sr which appears as higher breakthrough in the early elution volumes. The remaining Sr activity is strongly bound to these ion exchangers and the breakthrough remains stable at a lower breakthrough value through a large number of elutions. Bio-Rex 70 on the other hand does not exhibit the poorly bound Sr fraction and the breakthrough of Sr remains the lowest of the three ion exchangers through a moderate number of elutions and then the Sr breakthrough gradually increases with each additional elution

  9. Use of a visible light-cured periodontal dressing material as a temporary restoration for inlay/onlay preparations.

    Science.gov (United States)

    Apltauer, James J; Silver, Joel; Friedman, Lawrence J; Resnick, Steven J; Berkowitz, Leonard I; Rochlen, Glenn K; Blye, Jeffrey S; Hershkowitz, David H; Berkowitz, Gary S

    2013-01-01

    There are numerous materials that are used as temporaries for inlay and onlay preparations while the permanent restoration is being made. This article looks at 2 types of temporary materials that were placed into inlay or onlay preparations by student dentists: a methylmethacrylate acrylic material (DuraLay Inlay Pattern Resin) and a visible light-cured (VLC) periodontal surgical dressing (Barricaid). The resilience and effectiveness of both products are compared and evaluated for use as temporary restorations in inlay or onlay preparations. The study found that use of the VLC periodontal dressing material offers a novel technique for a quick and efficient method to provide a temporary restoration for various inlay and onlay preparations.

  10. Longevity of restorations in posterior teeth and reasons for failure.

    Science.gov (United States)

    Hickel, R; Manhart, J

    2001-01-01

    This article compiles a survey on the longevity of restorations in stress-bearing posterior cavities and assesses possible reasons for failure. The dental literature predominantly of the last decade was reviewed for longitudinal, controlled clinical studies and retrospective cross-sectional studies of posterior restorations. Only studies investigating the clinical performance of restorations in permanent teeth were included. Longevity and annual failure rates of amalgam, direct composite restorations, glass ionomers and derivative products, composite and ceramic inlays, and cast gold restorations were determined for Class I and II cavities. Annual failure rates in posterior stress-bearing restorations are: 0% to 7% for amalgam restorations, 0% to 9% for direct composites, 1.4% to 14.4% for glass ionomers and derivatives, 0% to 11.8% for composite inlays, 0% to 7.5% for ceramic restorations, 0% to 4.4% for CAD/CAM ceramic restorations, and 0% to 5.9% for cast gold inlays and onlays. Longevity of dental restorations is dependent upon many different factors that are related to materials, the patient, and the dentist. The principal reasons for failure were secondary caries, fracture, marginal deficiencies, wear, and postoperative sensitivity. A distinction must be made between factors causing early failures and those that are responsible for restoration loss after several years of service.

  11. Small-aperture corneal inlay in patients with prior radial keratotomy surgeries

    Directory of Open Access Journals (Sweden)

    Huseynova T

    2013-09-01

    Full Text Available Tukezban Huseynova,1,* Tomomi Kanamori,1 George O Waring IV,2 Minoru Tomita1,3,* 1Shinagawa LASIK Center, Chiyoda-ku, Tokyo, Japan; 2Medical University of South Carolina, Storm Eye Institute, Charleston, SC, USA; 3Department of Ophthalmology, Wenzhou Medical College, Wenzhou, People's Republic of China *These authors contributed equally to this study Abstract: This paper describes the 3-month results of two patients who underwent KAMRA™ (AcuFocus, Inc, Irvine, CA, USA inlay implantation surgery with a history of prior radial keratotomy. The refractive error just before KAMRA inlay implantation was corrected in one patient with a laser-assisted in situ keratomileusis (LASIK procedure. The post-inlay implantation surgery results showed effective uncorrected near visual acuity outcomes with no impact on uncorrected distance visual acuity in both patients. Keywords: KAMRA™, RK, LASIK, uncorrected distance visual acuity, refractive error, uncorrected near visual acuity

  12. Byzantine Crosses with Inlay in the South-Western Crimea

    Directory of Open Access Journals (Sweden)

    Elzara A. Khayredinova

    2017-11-01

    Full Text Available Archaeological materials played an important role for the studies of the history of Christianity in the South-Western Crimea. Especially interesting are individual artefacts of Christian cult, pectoral crosses in particular. Crosses in costumes of the barbarians of the South-Western Crimea appear in the second half of the 6th century. They were mainly mass goods that were brought from Byzantium and were manufactured in Cherson and jewellery workshops of the country of Dori. This paper analyses byzantine crosses from 550–625 AD with inlay. It was the earliest and the most popular type of crosses among the Crimean Goths. The location of beads and crosses documented in situ in graves provides arguments to reconstruct necklaces and costume which components they formed. Only women and girls wore these crosses in necklaces, accompanied with beads and varied amulets. Many necklaces contained several crosses, which could be explained as the understanding of cross as an amulet. Crosses, as other things of personal godliness, as well as numerous objects with Christian symbols, are a bright evidence of Christianity spreading in Crimea. Crimean finds enlarge our notion of everyday Christian culture in the early mediaeval period, thus forming a striking evidence of close economic and cultural relations of the Crimea and the Byzantine Empire in the early Middle Ages.

  13. Flexural strength of In-Ceram alumina and In-Ceram zirconia core materials.

    Science.gov (United States)

    Chong, Kok-Heng; Chai, John; Takahashi, Yutaka; Wozniak, Wayne

    2002-01-01

    The study compared the flexural strength of In-Ceram alumina and In-Ceram zirconia systems. The probability of failure of the two glass-infiltrated ceramic core materials was analyzed with and without lamination with Vitadur-alpha porcelain. Ten uniform beams of core materials as well as 10 beams of laminated core materials were fabricated for In-Ceram alumina and In-Ceram zirconia. The samples were subjected to three-point bending tests. Flexural strength for both ceramic core materials was determined with and without their porcelain laminations. The strength data were analyzed using the Weibull method. Modes of failure for both systems were determined using scanning electron micrography. The strength of the In-Ceram zirconia system was significantly higher than In-Ceram alumina when comparing their core materials with and without porcelain lamination. The failure mode for both systems was predominantly transgranular fracture of alumina platelets. In-Ceram zirconia demonstrated higher flexural strength than In-Ceram alumina.

  14. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography.

    Science.gov (United States)

    Türk, Ayşe Gözde; Sabuncu, Metin; Ünal, Sena; Önal, Banu; Ulusoy, Mübin

    2016-01-01

    The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT) to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany) after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs), allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply), and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (pinlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442) and after (p=0.00001466) cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively). The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after cementation.

  15. Influence of a proximal margin elevation technique on marginal adaptation of ceramic inlays.

    Science.gov (United States)

    Zaruba, M; Göhring, T N; Wegehaupt, F J; Attin, T

    2013-03-01

    Evaluating the effect of a proximal margin elevation technique on marginal adaptation of ceramic inlays. Class II MOD-cavities were prepared in 40 human molars and randomly distributed to four groups (n = 10). In group EN (positive control) proximal margins were located in enamel, 1 mm above the cementoenamel junction, while 2 mm below in groups DE-1In, DE-2In and DE. The groups DE-1In, DE-2In and DE simulated subgingival location of the cervical margin. In group DE-1In one 3 mm and in group DE-2In two 1.5 mm composite layers (Tetric) were placed for margin elevation of the proximal cavities using Syntac classic as an adhesive. The proximal cavities of group DE remained untreated and served as a negative control. In all groups, ceramic inlays (Cerec 3D) were adhesively inserted. Replicas were taken before and after thermomechanical loading (1.200.000 cycles, 50/5°C, max. load 49 N). Marginal integrity (tooth-composite, composite-inlay) was evaluated with scanning electron microscopy (200×). Percentage of continuous margin (% of total proximal margin length) was compared between groups before and after cycling using ANOVA and Scheffé post-hoc test. After thermomechanical loading, no significant differences were observed between the different groups with respect to the interface composite-inlay and tooth-composite with margins in dentin. The interface tooth-composite in enamel of group EN was significantly better compared to group DE-2In, which was not different to the negative control group DE and DE-1In. Margin elevation technique by placement of a composite filling in the proximal box before insertion of a ceramic inlay results in marginal integrities not different from margins of ceramic inlays placed in dentin.

  16. Power density of various light curing units through resin inlays with modified layer thickness

    Directory of Open Access Journals (Sweden)

    Sung-Ok Hong

    2012-08-01

    Full Text Available Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr. The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05. Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

  17. Inlay fixed partial denture as a conservative approach for restoring posterior missing teeth: a clinical report.

    Science.gov (United States)

    Iglesia-Puig, Miguel A; Arellano-Cabornero, Alfonso

    2003-05-01

    Inlay fixed partial dentures luted by use of adhesive procedures offer a clinical alternative for the restoration of single missing posterior teeth. The introduction of ceromers and fiber-reinforced composites and the continuous improvement of adhesive systems and luting agents make this type of restoration possible, offering good aesthetic and functional results. The procedure is minimally invasive and conservative. This clinical report reviews the factors influencing the diagnosis and the clinical indications for an inlay fixed partial denture. In addition, a patient treatment is presented to illustrate the clinical procedures involved.

  18. Utilization of ceromer inlays/onlays for replacement of amalgam restorations.

    Science.gov (United States)

    Koczarski, M J

    1998-05-01

    Fiber-reinforced Ceromer technology has been recommended for a variety of restorations, including inlays/onlays, crowns and bridges, and direct restorations. Ideal restorative dental materials must exhibit adequate physical properties and fit, as well as ease and predictability of fabrication and repair. The Ceromer restorative material combines the positive attributes of indirect composite restorations, feldspathic ceramics, and cast-gold restorations. This article reviews the material properties and aesthetic characteristics inherent to Ceromers, as well as the appropriate preparation and adhesive techniques for inlay/onlay restorations.

  19. Bauxite Mining and Alumina Refining

    OpenAIRE

    Donoghue, A. Michael; Frisch, Neale; Olney, David

    2014-01-01

    Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust,...

  20. Production of pure sintered alumina

    International Nuclear Information System (INIS)

    Rocha, J.C. da; Huebner, H.W.

    1982-01-01

    With the aim of optimizing the sintering parameters, the strength of a large number of alumina samples was determined which were produced under widely varying sintering conditions and with different amounts of MgO content. The strength as a function of sintering time or temperature was found to go through a maximum. With increasing time, this maximum is shifted to lower temperatures, and with decreasing temperature to longer times. Data pairs of sintering times and temperatures which yeld the strength maximum were determined. The value of the strength at the maximum remains unchanged. The strength is high (= 400 MN/m 2 , at a grain size of 3 um and a porosity of 2 per cent) and comparable to foreign aluminas produced for commercial purposes, or even higher. The increase in the sintering time from 1 h to 16 h permits a reduction of the sintering temperature from 1600 to 1450 0 C without losing strength. The practical importance of this fact for a production of sintered alumina on a large scale is emphasized. (Author) [pt

  1. Acetic acid mediated interactions between alumina surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kimiyasu, E-mail: sato.kimiyasu@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Y Latin-Small-Letter-Dotless-I lmaz, Hueseyin [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Gebze Institute of Technology, Materials Science and Engineering Department, 41400, Gebze-Kocaeli (Turkey); Ijuin, Atsuko; Hotta, Yuji; Watari, Koji [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

    2012-02-01

    Low-molecular-weight organic acids have been known to modify colloidal stability of alumina-based suspensions. We investigated interaction forces between alumina surfaces mediated by acetic acid which is one of the simplest organic acids. Forces between alumina surfaces were measured using the colloid-probe method of atomic force microscope (AFM). Repulsive forces attributed to steric repulsion due to adsorbed molecules and electrostatic repulsion dominated the interaction. Results of rheological characterization of the alumina slurry containing acetic acid supported the finding.

  2. Comparison of a hydrogel corneal inlay and monovision laser in situ keratomileusis in presbyopic patients: focus on visual performance and optical quality

    Directory of Open Access Journals (Sweden)

    Verdoorn C

    2017-09-01

    Full Text Available Cornelis Verdoorn Lasik Centrum Eye Clinic, Boxtel, the Netherlands Purpose: To compare the visual performance and optical quality after Raindrop Near Vision Inlay implantation or monovision LASIK for the correction of presbyopia. Materials and methods: In this retrospective case-series study, patients previously treated in the nondominant eye with monovision LASIK were compared with patients previously implanted with Raindrop Near Vision Inlay. The study enrolled 16 inlay and 15 monovision LASIK patients. Uncorrected near visual acuity, uncorrected distance visual acuity, binocular stereopsis, patient satisfaction, and patient task performance were assessed. Results: Postoperatively, the mean spherical equivalent was -0.66 D (0.78 SD for the inlay group and -1.03 D (0.56 SD for the monovision LASIK group. Monocularly, at uncorrected near distances, 60% of inlay patients and 47% of monovision LASIK patients achieved ≥20/20. Monocularly, at uncorrected far distances, 75% of inlay patients and 40% of monovision LASIK patients achieved ≥20/32 vision. Binocularly, at near distances, 79% of inlay patients and 53% of monovision LASIK patients obtained ≥20/20 vision. All patients achieved ≥20/20 binocularly for distance. On average, inlay patients obtained 98 seconds of arc and monovision LASIK patients obtained 286 seconds of arc for stereopsis. Most (79% of the inlay patients and 66% of monovision LASIK patients were satisfied with their near vision, while 86% of inlay patients and 67% of monovision LASIK patients were satisfied with their distance vision. Conclusion: Patients receiving corneal inlays demonstrated better near and distance visual acuities, binocular stereopsis, task performance, and satisfaction, when compared to patients treated with monovision LASIK. Keywords: presbyopia, corneal inlays, monovision, laser in situ keratomileusis, LASIK, Raindrop Near Vision Inlay

  3. Methodology of licensing for field applications of Weld Inlay and Ultrasonic Nanocrystal Surface Modification

    International Nuclear Information System (INIS)

    Cho, Hong Seok; Jung, Kwang Woon; Park, Ik Keun; Pyun, Young Sik

    2015-01-01

    There are many attempts to relieve or change high tensile residual stress to compressive residual stress for a mitigation of PWSCC. LSP(Laser Shot Peening) and WJP(Water Jet Peening) have been applied in several NPPs of Japan and technical and topical reports under Materials Reliability Program of EPRI(Electric Power Research Institute ) USA have been developed. Weld Inlay technology and UNSM(Ultrasonic Nanocrystal Surface Modification) technology using ultrasonic vibration energy as the method for a mitigation of tensile residual stress generated after Weld Inlay have been developing in Korea. So in this study, the methodology of licensing for field application of these technologies is suggested. The results of residual stress measured before and after UNSM for Weld Inlay specimens using UNSM equipment of domestic source technology holdings to obtain an equivalent effect, which has the simplification of equipment and the flexibility of field application in comparison with LSP and WJP, indicated to obtain a mitigation effect of residual stress until 0.5 mm of surface depth. In order to accomplish field application of Weld Inlay that the Code Case was already developed, the approval of a regulation agency through the preparation of TR or RR based on ASME Code Case N-766, N-803 is necessary

  4. Methodology of licensing for field applications of Weld Inlay and Ultrasonic Nanocrystal Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hong Seok; Jung, Kwang Woon [KEPCO KPS, Naju (Korea, Republic of); Park, Ik Keun [Seoul National Univ, Seoul (Korea, Republic of); Pyun, Young Sik [Sun Moon University, Asan (Korea, Republic of)

    2015-10-15

    There are many attempts to relieve or change high tensile residual stress to compressive residual stress for a mitigation of PWSCC. LSP(Laser Shot Peening) and WJP(Water Jet Peening) have been applied in several NPPs of Japan and technical and topical reports under Materials Reliability Program of EPRI(Electric Power Research Institute ) USA have been developed. Weld Inlay technology and UNSM(Ultrasonic Nanocrystal Surface Modification) technology using ultrasonic vibration energy as the method for a mitigation of tensile residual stress generated after Weld Inlay have been developing in Korea. So in this study, the methodology of licensing for field application of these technologies is suggested. The results of residual stress measured before and after UNSM for Weld Inlay specimens using UNSM equipment of domestic source technology holdings to obtain an equivalent effect, which has the simplification of equipment and the flexibility of field application in comparison with LSP and WJP, indicated to obtain a mitigation effect of residual stress until 0.5 mm of surface depth. In order to accomplish field application of Weld Inlay that the Code Case was already developed, the approval of a regulation agency through the preparation of TR or RR based on ASME Code Case N-766, N-803 is necessary.

  5. Multi-channel peristaltic pump for microfluidic applications featuring monolithic PDMS inlay

    DEFF Research Database (Denmark)

    Skafte-Pedersen, Peder; Sabourin, David; Dufva, Martin

    2009-01-01

    flow. Both use a monolithic PDMS pumping inlay featuring three-dimensional geometries favourable to pumping applications and 12 wholly integrated circular channels. Flow rates in the sub-µL min-1 to µL min-1 range were obtained. Channel-to-channel flow rate variability was comparable to a commercial...

  6. A Systematic Review of Ceramic Inlays in Posterior Teeth : An Update

    NARCIS (Netherlands)

    Pol, Christiaan W. P.; Kalk, Warner

    2011-01-01

    Purpose: Ceramic materials, first introduced in restorative dentistry in the late 18th century, offer a wide range of possibilities and exhibit esthetic properties. The last systematic reviews on the subject of ceramic inlays were published in 2003. All articles published up to 2001 were surveyed

  7. [Clinical study comparing at 5 years a ceramic and a ceromer used for making esthetic inlays].

    Science.gov (United States)

    Khairallah, C; Sabbagh, J; Hokayem, A

    2009-06-01

    Thirty-six inlays, equally divided between a vitro ceramic and a composite resin, were bonded in pair, on the same type of teeth in fifteen patients. They were followed for a mean period of 60 months. The results showed that both materials were clinically acceptable for restoring posterior teeth, even though ceramic yielded better results concerning colour match.

  8. Ceramic inlays : effect of mechanical cycling and ceramic type on restoration-dentin bond strength

    NARCIS (Netherlands)

    Trindade, F.Z.; Kleverlaan, C.J.; da Silva, L.H.; Feilzer, A.J.; Cesar, P.F.; Bottino, M.A.; Valandro, L.F.

    2016-01-01

    This study aimed to evaluate the bond strength between dentin and five different ceramic inlays in permanent maxillary premolars, with and without mechanical cycling. One hundred permanent maxillary premolars were prepared and divided into 10 groups (n=10) according to the ceramic system (IPS e.Max

  9. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique

    Directory of Open Access Journals (Sweden)

    TURK Ayse Gozde

    2018-02-01

    Full Text Available Abstract Optical coherence tomography (OCT has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany. Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05. Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 μm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 μm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively. On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00 and OCT (p = 0.00. Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

  10. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Science.gov (United States)

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  11. Ion guiding in alumina capillaries

    DEFF Research Database (Denmark)

    Juhász, Z.; Sulik, B.; Biri, S.

    2009-01-01

    focus our attention to the measurements with the MCP array. The alumina capillaries were prepared by electro-chemical oxidation of aluminium foils. For the present experiments guiding of 3-6 keV Ne ions has been studied in two samples with capillary diameter of about 140 nm and 260 nm and with capillary...... length of about 15 μm. At these energies, the ions have been efficiently guided by the capillaries up to few degrees tilt angle. In this work, we compare the results obtained by the energy dispersive spectrometer to those studied by the MCP array....

  12. Preparation of alumina-β'

    International Nuclear Information System (INIS)

    Casarini, J.R.; Souza, D.P.F.

    1984-01-01

    Alumina - (β + β') in powder, with composition of 8.85% Na 2 0 + 0.75% Li 2 0 + 90.40% Al 2 O 3 is obtained using the zeta process. The phase transformation β→β' can be seen with powder X-ray diffraction. It was observed that the efficiency of the transformation is related to the processing and purity of the raw material. Impurities as Ca and Si difficult the phase transformation β→β'. (E.G.) [pt

  13. Ordering of Octahedral Vacancies in Transition Aluminas

    NARCIS (Netherlands)

    Wang, Yuan Go; Bronsveld, Paul M.; Hosson, Jeff Th.M. De; Djuričić, Boro; McGarry, David; Pickering, Stephen

    1998-01-01

    The microstructure of transition aluminas obtained via the dehydration of boehmite has been characterized by using transmission electron microscopy (TEM). The presence of γ-, δ-, and θ-aluminas was identified by using selected-area electron diffraction. Modifications that resulted from the

  14. alumina phase transformation from thermal decomposition

    African Journals Online (AJOL)

    HOD

    Alumina is one of the major components used as catalyst support, which is especially important with regard to ... alumina, has been a major catalytic support in automotive and petroleum industries, as well as in adsorption ..... Catalyst in Steam Reforming of Dimethyl ether: Cu/γ-Al2O3/Al Catalyst Degradation Behaviors and.

  15. Load-bearing capacity of indirect inlay-retained fixed dental prostheses made of particulate filler composite alone or reinforced with E-glass fibers impregnated with various monomers.

    Science.gov (United States)

    Özcan, Mutlu; Koekoek, Winand; Pekkan, Gurel

    2012-08-01

    The load-bearing capacity and failure types of indirect inlay-retained fixed dental prostheses (FDP), made of particulate filler composite (PFC) (Estenia) alone or reinforced with E-glass fibers impregnated with various monomers were evaluated. Indirect inlay-retained FDPs were made between first premolars and first molars (N=30, 10/per group). The inlay parts of the specimens were silica coated and silanized and the specimens were cemented with dual-polymerized resin cement under ultrasonic vibrations. The experimental groups were as follows: Group 1: FRC1 (BR-100, UTMA) + PFC; Group 2: FRC2 (everStick C&B, Bis-GMA/PMMA) + PFC; Group 3: PFC only. The specimens were kept in distilled water at 37 °C for one month and then subjected to fracture strength test. No significant difference was found between the Group 1 and Group 2 FDPs (1357±301 N and 1213±316 N, respectively) (p>0.05) (ANOVA). Group 3 (856±299 N) showed significantly lower results than those of FRC reinforced groups (pinlay cavities. FDPs made of PFC only showed mainly catastrophic fracture of the pontic. In the FRC reinforced groups, predominantly delamination of the veneering was observed. The use of silica coating and silanization in combination with the dual-polymerized resin cement used; under ultrasonic cementation procedure provided sufficient adhesion to withstand static loading forces at the cementation interface, since the failures were predominantly delamination of the veneering in the FRC reinforced groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Damages of the tibial post in constrained total knee prostheses in the early postoperative course – a scanning electron microscopic study of polyethylene inlays

    Directory of Open Access Journals (Sweden)

    Reichelt Rudolf

    2008-06-01

    Full Text Available Abstract Background Investigation of the risk of fracture of the polyethylene (PE inlay in constrained total knee prostheses. Methods Three unused and seven polyethylene inlays that had been implanted in a patient's knee for an average of 25.4 months (min 1.1 months, max 50.2 months were investigated using scanning electron microscopy (SEM. All inlays were of the same type and size (Genesis II constrained, Smith & Nephew. The PE surface at the transition from the plateau to the post was analyzed. Results The unused inlays had fissure-free surfaces. All inlays that had been implanted in a patient's knee already had distinct fissures at the front and backside of the post. Conclusion The fissures of the transition from the plateau to the post indicated a loading-induced irreversible mechanical deformation and possibly cause the fracture of the inlay.

  17. Image quality of grating target in model eye when viewed through a small-aperture corneal inlay.

    Science.gov (United States)

    Inoue, Makoto; Bissen-Miyajima, Hiroko; Arai, Hiroyuki; Noda, Toru; Ohnuma, Kazuhiko; Hirakata, Akito

    2014-07-01

    To evaluate the quality of the image of a grating target placed in a model eye and viewed through a small-aperture corneal inlay. Kyorin Eye Center, Tokyo, Japan. Experimental study. A Kamra corneal inlay was placed on the anterior surface of a fluid-filled model eye, and a United States Air Force target and a calibrated scale were placed on the inner surface of the model eye. With a flat contact lens or a contact or noncontact wide-angle viewing system, the contrast of the grating images and the field of view through the inlay were compared with those without the inlay. A blurred dark ring was observed with the flat contact lens and MiniQuad wide-viewing contact lens in the model eye with the inlay. The contrast of the gratings was significantly decreased at 16 cycles/mm (P=.028), 32 cycles/mm (P=.046), and 64 cycles/mm (P=.015). With the Resight noncontact wide-angle viewing system, the field of view was reduced from 62 degrees to 32 degrees when the front lens was at 7.0 mm and slightly reduced from 75 degrees to 62 degrees at 5.0 mm with the inlay. The contrast of grating images observed through the inlay was significantly reduced when viewed with the flat contact lens. The field of view through the wide-angle viewing system was also altered. However, the noncontact wide-angle viewing system may be recommended for vitreous surgeries in eyes with the inlay by adjusting the distance of the front lens from the cornea. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. Comparison of Contrast Sensitivity and Through Focus in Small-Aperture Inlay, Accommodating Intraocular Lens, or Multifocal Intraocular Lens Subjects.

    Science.gov (United States)

    Vilupuru, Srividhya; Lin, Ling; Pepose, Jay S

    2015-07-01

    To compare monocular and binocular mesopic contrast sensitivity and through focus following monocular implantation with KAMRA small-aperture inlay (AcuFocus, Irvine, California, USA) vs binocular implantation with an accommodating or multifocal intraocular lens (IOL) implant. Three-treatment randomized clinical trial of presbyopia-correcting IOLs with comparison to results from a previous nonrandomized multicenter clinical trial on the KAMRA corneal inlay. Study population of 507 subjects with KAMRA inlays; predetermined subgroups included 327 subjects that underwent contrast sensitivity testing and another 114 subjects for defocus curve testing, along with 78 subjects randomized between bilateral Crystalens Advanced Optics (AO) (Bausch + Lomb Surgical, Aliso Viejo, California, USA), AcrySof IQ ReSTOR +3.0 D (Alcon Laboratories, Fort Worth, Texas, USA), or Tecnis +4D Multifocal (MF) (Abbott Medical Optics, Santa Ana, California, USA) IOL. KAMRA inlay subjects demonstrated improved intermediate and near vision with minimal to no change to distance vision, better contrast sensitivity in the inlay eye when compared to the multifocals, and better binocular contrast sensitivity when compared to all 3 intraocular lenses. Crystalens AO was superior in uncorrected intermediate vision compared to the KAMRA inlay, but not in distance-corrected intermediate, and was worse in near vision. The multifocals were superior in near vision at their respective optimum near focus points, but worse in intermediate vision compared to both KAMRA inlay and Crystalens AO. The demonstrated performance of these devices should be considered, along with subjects' visual demands and expectations, degree of crystalline lens dysfunction, and other ocular characteristics, in guiding the selection of small-aperture corneal inlay or specific intraocular lens in the correction of presbyopia. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Comparison of a hydrogel corneal inlay and monovision laser in situ keratomileusis in presbyopic patients: focus on visual performance and optical quality

    OpenAIRE

    Verdoorn C

    2017-01-01

    Cornelis Verdoorn Lasik Centrum Eye Clinic, Boxtel, the Netherlands Purpose: To compare the visual performance and optical quality after Raindrop Near Vision Inlay implantation or monovision LASIK for the correction of presbyopia. Materials and methods: In this retrospective case-series study, patients previously treated in the nondominant eye with monovision LASIK were compared with patients previously implanted with Raindrop Near Vision Inlay. The study enrolled 16 inlay and 15 monovision...

  20. [The finite element analysis of stress distribution in different size of MO cavities restored with composite resin inlays].

    Science.gov (United States)

    Zhang, Long; Lu, Yi; Yang, Bo-song; Guo, Yan; Li, Fang-ping

    2015-04-01

    To explore the effect of different depth and width of meiso-occlusal (Class II) cavity type on the tooth tissue resistance stress after restoration with composite resin inlays. The 3-D finite element model of mandibular first molar with meiso-occlusal (Class II) cavity restored with composite resin inlay was established by using CBCT scanning and reverse engineering software Mimics, Geomagic Studio, and finite element analysis software ANSYS. Comparative analysis of restoration with different depth and width meiso-occlusal (Class II) cavity under the same load of perpendicular and 45° deviation was explored, and finally the main stress and Von-mises stress changed as well as stress distribution were analyzed. The main stress was located in the gingival wall opposite to the inlay, while the major stress concentration area of the tooth was distributed near the canal at the bottom of the cavity. With the increase of the depth and width, the main stress and Von-mises stress distribution areas of tooth were getting larger. The Von-mises stress of tooth was influenced by the width variation of the cavity, while that depth change of cavity was affected by Von Mises stress of the inlay. With the increase of the depth and width of the cavity as well as lateral loading force, the peak stress of tooth with inlays increased and the distribution of stress concentration is modified after meiso-occlusal (Class II) cavity being inlayed with composite resin.

  1. Joining of alumina via copper/niobium/copper interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Robert A.; Chapman, Daniel R.; Danielson, David T.; Glaeser, Andreas M.

    2000-03-15

    Alumina has been joined at 1150 degrees C and 1400 degrees C using multilayer copper/niobium/copper interlayers. Four-point bend strengths are sensitive to processing temperature, bonding pressure, and furnace environment (ambient oxygen partial pressure). Under optimum conditions, joints with reproducibly high room temperature strengths (approximately equal 240 plus/minus 20 MPa) can be produced; most failures occur within the ceramic. Joints made with sapphire show that during bonding an initially continuous copper film undergoes a morphological instability, resulting in the formation of isolated copper-rich droplets/particles at the sapphire/interlayer interface, and extensive regions of direct bonding between sapphire and niobium. For optimized alumina bonds, bend tests at 800 degrees C-1100 degrees C indicate significant strength is retained; even at the highest test temperature, ceramic failure is observed. Post-bonding anneals at 1000 degrees C in vacuum or in gettered argon were used to assess joint stability and to probe the effect of ambient oxygen partial pressure on joint characteristics. Annealing in vacuum for up to 200 h causes no significant decrease in room temperature bend strength or change in fracture path. With increasing anneal time in a lower oxygen partial pressure environment, the fracture strength decreases only slightly, but the fracture path shifts from the ceramic to the interface.

  2. Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants.

    Science.gov (United States)

    Traini, Tonino; Sorrentino, Roberto; Gherlone, Enrico; Perfetti, Federico; Bollero, Patrizio; Zarone, Ferdinando

    2015-07-01

    Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

  3. Dissolution Kinetics of Alumina Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Batcheller, Thomas Aquinas

    2001-09-01

    Dissolution kinetics of alumina type non-radioactive calcine was investigated as part of ongoing research that addresses permanent disposal of Idaho High Level Waste (HLW). Calcine waste was produced from the processing of nuclear fuel at the Idaho Nuclear Technology and Engineering Center (INTEC). Acidic radioactive raffinates were solidified at ~500°C in a fluidized bed reactor to form the dry granular calcine material. Several Waste Management alternatives for the calcine are presented in the Idaho High Level Waste Draft EIS. The Separations Alternative addresses the processing of the calcine so that the HLW is ready for removal to a national geological repository by the year 2035. Calcine dissolution is the key front-end unit operation for the separations alternative.

  4. Three-year clinical performance of two indirect composite inlays compared to direct composite restorations

    Science.gov (United States)

    Ozakar-Ilda, Nurcan; Zorba, Yahya O.; Yildiz, Mehmet; Erdem, Vildan; Seven, Nilgun

    2013-01-01

    Objective: Despite the incremental build-up of resin composite restorations, their polymerization shrinkage during curing presents a serious problem. Indirect composite resin systems represent an alternative in overcoming some of the deficiencies of direct composite restorations. The hypothesis of the present study states that the clinical performance of restorations may be affected by different generation and application techniques. Study Design: Sixty restorations (20 DI system (Coltène/Whaledent AG, Altstätten, Switzerland) composite inlays, 20 Tescera ATL system (BISCO Inc. Schaumburg, Illinois, USA) composite inlays, and 20 direct composites) were applied to premolar teeth in 49 patients. Restorations were clinically evaluated by two examiners. Data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Wilcoxon Signed Ranks, and X2 tests. Results: The Tescera ATL system performed significantly better than both direct composite restorations (pinlay, direct composite restorations, indirect composite restorations. PMID:23524423

  5. [Improvement of light-cured indirect inlays durability by means of electromagnetic field].

    Science.gov (United States)

    Nidzel'skiĭ, M Ia; Korotetskaia-Zinkevich, V L

    2014-01-01

    The main strength characteristics of light-cured resins used for replacement of dental hard tissues defects are destructive stress by compression, microhardness, resistance to abrasion, impact and water absorption. The study focuses on some strength features of composite materials for inlays processed by electromagnetic field. Four sample series of light cured resin (Charisma, Heraus Kulzer, Germany) were used to assess strength features changes in various curing methods: 10 control samples were polymerized by conventional light-curing device, while 30 were additionally processed by electromagnetic field of various intensity (60, 80 and 100 Oe, 10 samples for each group). The obtained results confirm the positive effects of electromagnetic field on strength features of light-cured resins which improves the quality of inlays.

  6. Utilization of Ceramic Inlays for Sealing Implant Prostheses Screw Access Holes: A Case-Control Study.

    Science.gov (United States)

    Mihali, Sorin; Canjau, Silvana; Bratu, Emanuel; Wang, Hom-Lay

    2016-01-01

    The aim of this study was to evaluate, in a case control study, the esthetic and functional clinical performance of ceramic inlays used for covering the screw access hole in single monolithic lithium disilicate full-contour crowns bonded on computer-aided design/computer-aided manufacturing (CAD/CAM) prefabricated titanium abutments in order to eliminate the drawbacks of alternative restorative methods. Twenty-eight patients with missing teeth in the lateral areas (premolars and molars) received screw-retained implant restorations. In half of the restorations (n = 14), composite fillings were used to seal the access hole (control group), while the other half was sealed with ceramic inlays (test group). To determine the restoration occlusal wear, impressions were obtained after the restorations were finalized, at 1 year, and at 2 years follow-up. The casts were scanned with a 3D Scanner Design System recording the anatomical surfaces of the white model replicates. Wear amounts (μm) were calculated as the maximum loss in height of the occlusal surface. The clinical evaluation was carried out using a kit specifically designed for assessing the FDI criteria. Statistics were performed using analysis of variance (ANOVA). A total of 58 restorations were delivered, and after 2 years of follow-up, the wear values were 228.20 ± 54.68 μm for the control group and 65.20 ± 7.24 μm for the ceramic inlay group. One-way ANOVA showed significant differences among the vertical loss between these two groups (P inlays appears to be a predictable, esthetic, and successful method of sealing the screw holes of the screw-retained implant restorations.

  7. Marginal adaptation of four inlay casting waxes on stone, titanium, and zirconia dies.

    Science.gov (United States)

    Michalakis, Konstantinos X; Kapsampeli, Vassiliki; Kitsou, Aikaterini; Kirmanidou, Yvone; Fotiou, Anna; Pissiotis, Argirios L; Calvani, Pasquale Lino; Hirayama, Hiroshi; Kudara, Yukio

    2014-07-01

    Different inlay casting waxes do not produce copings with satisfactory marginal accuracy when used on different die materials. The purpose of this study was to evaluate the marginal accuracy of 4 inlay casting waxes on stone dies and titanium and zirconia abutments and to correlate the findings with the degree of wetting between the die specimens and the inlay casting waxes. The inlay casting waxes tested were Starwax (Dentaurum), Unterziehwachs (Bredent), SU Esthetic wax (Schuler), and Sculpturing wax (Renfert). The marginal opening of the waxes was measured with a stereomicroscope on high-strength stone dies and on titanium and zirconia abutments. Photographic images were obtained, and the mean marginal opening for each specimen was calculated. A total of 1440 measurements were made. Wetting between die materials and waxes was determined after fabricating stone, titanium, and zirconia rectangular specimens. A calibrated pipette was used to place a drop of molten wax onto each specimen. The contact angle was calculated with software after an image of each specimen had been made with a digital camera. Collected data were subjected to a 2-way analysis of variance (α=.05). Any association between marginal accuracy and wetting of different materials was found by using the Pearson correlation. The wax factor had a statistically significant effect both on the marginal discrepancy (F=158.31, Pdie material factor both on the marginal adaptation (F=503.47, Pdies provided wax copings with the best marginal integrity, followed by titanium and zirconia abutments. Unterziehwachs (Bredent), wax produced the best marginal adaptation on different die materials. A significant correlation was found between the marginal accuracy and the contact angle values. As the contact angle value became smaller, the marginal accuracy improved. All combinations of waxes and stone and titanium dies presented a high wettability. Copyright © 2014 Editorial Council for the Journal of Prosthetic

  8. Comparison of a hydrogel corneal inlay and monovision laser in situ keratomileusis in presbyopic patients: focus on visual performance and optical quality.

    Science.gov (United States)

    Verdoorn, Cornelis

    2017-01-01

    To compare the visual performance and optical quality after Raindrop Near Vision Inlay implantation or monovision LASIK for the correction of presbyopia. In this retrospective case-series study, patients previously treated in the nondominant eye with monovision LASIK were compared with patients previously implanted with Raindrop Near Vision Inlay. The study enrolled 16 inlay and 15 monovision LASIK patients. Uncorrected near visual acuity, uncorrected distance visual acuity, binocular stereopsis, patient satisfaction, and patient task performance were assessed. Postoperatively, the mean spherical equivalent was -0.66 D (0.78 SD) for the inlay group and -1.03 D (0.56 SD) for the monovision LASIK group. Monocularly, at uncorrected near distances, 60% of inlay patients and 47% of monovision LASIK patients achieved ≥20/20. Monocularly, at uncorrected far distances, 75% of inlay patients and 40% of monovision LASIK patients achieved ≥20/32 vision. Binocularly, at near distances, 79% of inlay patients and 53% of monovision LASIK patients obtained ≥20/20 vision. All patients achieved ≥20/20 binocularly for distance. On average, inlay patients obtained 98 seconds of arc and monovision LASIK patients obtained 286 seconds of arc for stereopsis. Most (79%) of the inlay patients and 66% of monovision LASIK patients were satisfied with their near vision, while 86% of inlay patients and 67% of monovision LASIK patients were satisfied with their distance vision. Patients receiving corneal inlays demonstrated better near and distance visual acuities, binocular stereopsis, task performance, and satisfaction, when compared to patients treated with monovision LASIK.

  9. Effect of ceramic thickness and composite bases on stress distribution of inlays--a finite element analysis.

    Science.gov (United States)

    Durand, Letícia Brandão; Guimarães, Jackeline Coutinho; Monteiro Junior, Sylvio; Baratieri, Luiz Narciso

    2015-01-01

    The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred.

  10. Accuracy of optical scanning methods of the Cerec®3D system in the process of making ceramic inlays

    Directory of Open Access Journals (Sweden)

    Trifković Branka

    2010-01-01

    Full Text Available Background/Aim. One of the results of many years of Cerec® 3D CAD/CAM system technological development is implementation of one intraoral and two extraoral optical scanning methods which, depending on the current indications, are applied in making fixed restorations. The aim of this study was to determine the degree of precision of optical scanning methods by the use of the Cerec®3D CAD/CAM system in the process of making ceramic inlays. Methods. The study was conducted in three experimental groups of inlays prepared using the procedure of three methods of scanning Cerec ®3D system. Ceramic inlays made by conventional methodology were the control group. The accuracy of optical scanning methods of the Cerec®3D system computer aided designcomputer aided manufacturing (CAD/CAM was indirectly examined by measuring a marginal gap size between inlays and demarcation preparation by scanning electron microscope (SEM. Results. The results of the study showed a difference in the accuracy of the existing methods of scanning dental CAD/CAM systems. The highest level of accuracy was achieved by the extraoral optical superficial scanning technique. The value of marginal gap size inlays made with the technique of extraoral optical superficial scanning was 32.97 ± 13.17 μ. Techniques of intraoral optical superficial and extraoral point laser scanning showed a lower level of accuracy (40.29 ± 21.46 μ for inlays of intraoral optical superficial scanning and 99.67 ± 37.25 μ for inlays of extraoral point laser scanning. Conclusion. Optical scanning methods in dental CAM/CAM technologies are precise methods of digitizing the spatial models; application of extraoral optical scanning methods provides the hightest precision.

  11. Influence of Two Desensitizer Agents on the Microleakage of Adhesively Luted Ceramic Inlays

    Science.gov (United States)

    Celik, Esra Uzer; Kumbaraci, Nazli; Cal, Ebru; Turkun, Murat

    2011-01-01

    Objectives: The purpose of this study was to evaluate the effects of two different desensitizers (Hemaseal & Cide and Aqua Prep F) on the microleakage of ceramic inlay restorations luted with adhesive resin cement. Methods: Cylindrical Class V cavities were prepared on the buccal surfaces of thirty extracted human third molars. One of the desensitizers (either Hemaseal&Cide, Advantage Dental Products Inc. or Aqua-Prep F, Bisco) was applied to the cavities. Ten samples were used as controls. Ceramic inlays were fabricated using the heat-pressed glass ceramic technique (IPS Empress II). Inlay restorations were luted using adhesive cement (Variolink II, Ivoclar-Vivadent). The restorations were properly finished, stored in distilled water at 37°C for 24 h and subjected to 1000 thermal cycles. The microleakage scores were examined using a stereomicroscope at the 30x magnification after each sample was stained with 0.5% basic fuchsin. The data were analyzed using Kruskall Wallis and Mann Whitney U tests (P=0.05). Results: Aqua-Prep F samples showed significantly higher microleakage scores at the enamel margins than did the Hemaseal & Cide and control groups (Pinlay restorations luted with adhesive luting cement, while Aqua-Prep F increased the leakage scores at the enamel margins. PMID:21228958

  12. Biological corneal inlay for presbyopia derived from small incision lenticule extraction (SMILE).

    Science.gov (United States)

    Liu, Yu-Chi; Teo, Ericia Pei Wen; Ang, Heng Pei; Seah, Xin Yi; Lwin, Nyein Chan; Yam, Gary Hin Fai; Mehta, Jodhbir S

    2018-01-30

    Corneal inlays are a relatively new treatment option for presbyopia. Using biological inlays, derived from lenticules extracted from small incision lenticule extraction, may offer advantages over commercialized synthetic inlays in the aspect of biocompatibility. We conducted a non-human primate study to evaluate the safety, predictability, efficacy and tissue response after autogeneic, decellularized xenogeneic and xenogeneic lenticule implantation. The lenticule implantation effectively resulted in central corneal steepening (simulated keratometric values increased by 1.8-2.3 diopters), central hyper-prolate changes (asphericity Q values changed by -0.26 to -0.36), corneal anterior surface elevation (7.7-9.3 μm) and reasonable effective zone (1.5-1.8 times of the lenticule physical diameter), with no differences among the three groups. Slit lamp microscopy, transmission electron microscopy, confocal microscopy, histology and immunohistochemistry analyses confirmed the biocompatibility of the autogeneic and decellularized lenticules, whereas one eye in the xenogeneic group developed corneal stromal rejection during the study period. Our results showed that lenticule implantation has the potential for the management of presbyopia, and provide the basis for future clinical studies. The decellularization process may increase the potential utilization of lenticules without changing the efficacy.

  13. THE MARGINAL FIT OF MILLED-CERAMIC INLAYS – A COMPARATIVE THREE DIMENSIONAL AND MICROSCOPIC RESEARCH

    Directory of Open Access Journals (Sweden)

    Sorana BACIU

    2017-03-01

    Full Text Available Objective: The main goal of the present study is to compare two methods for evaluating the marginal fit of fixed prosthetic restorations. For this purpose we used a milled ceramic material, out of which we obtained class I inlays. The marginal gap was analyzed using micro CT and electronic microscopy. Materials and methods: After extraction of four caries-free mandibular first molars, first class inlay cavities were prepared. The marginal gap was analyzed circumferentially at the occlusal margin using a Bruker micro CT, by measuring the distance at the occlusal limit of the cavities, between the restoration and the tooth in several points for every surface of each tooth before cementing. For the second method SEM technology was used, and measurements were made at the occlusal limit of the cavities, between the restoration and the tooth in 50 microns steps. The data were compared with One–way ANOVA with Tukey’s Multiple Comparison Test performed using 5.00 for Windows (GraphPad Prism 5.00 Software, San Diego, California USA. Results and discussion: For both methods we obtained clinical acceptable values of the marginal gap for the milled ceramic inlays. The null hypothesis was rejected. We obtained statistical significant differences of the measured gaps using the two above mentioned methods. Conclusions: Both evaluation methods are reliable for measuring the marginal gap of fixed prosthetic restorations, each method having specific indications, advantages and disadvantages. They offer indispensable information which lead to improvement of the restorative treatments.

  14. Control of porosity in alumina for catalytic purposes - a review; Controle de porosidade em aluminas para fins cataliticos - uma revisao

    Energy Technology Data Exchange (ETDEWEB)

    Moure, Gustavo Torres [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Hidrorrefino, Lubrificantes e Parafinas; Morgado Junior, Edisson [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Craqueamento Catalitico; Figueiredo, Cecilia Maria C.

    1999-12-01

    In recent years, the Alumina Group, of the Catalysts Division of CENPES, has dedicated research to develop and characterize alumina for the catalytic processes of interest to PETROBRAS. Control of the texture of the alumina and, consequently, the alumina based catalysts, is crucially important to their adequacy and performance. Knowledge of the porosity formation mechanisms in alumina was fundamental for the development of catalysts to satisfy the demand from PETROBRAS. This comprises the scope of this review. (author)

  15. Processing of Alumina-Toughened Zirconia Composites

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2003-01-01

    Dense and crack-free 10-mol%-yttria-stabilized zirconia (10YSZ)-alumina composites, containing 0 to 30 mol% of alumina, have been fabricated by hot pressing. Release of pressure before onset of cooling was crucial in obtaining crack-free material. Hot pressing at 1600 C resulted in the formation of ZrC by reaction of zirconia with grafoil. However, no such reaction was observed at 1500 C. Cubic zirconia and -alumina were the only phases detected from x-ray diffraction indicating no chemical reaction between the composite constituents during hot pressing. Microstructure of the composites was analyzed by scanning electron microscopy and transmission electron microscopy. Density and elastic modulus of the composites followed the rule-of-mixtures. Addition of alumina to 10YSZ resulted in lighter, stronger, and stiffer composites by decreasing density and increasing strength and elastic modulus.

  16. Two-year clinical evaluation of a self-adhesive luting agent for ceramic inlays.

    Science.gov (United States)

    Peumans, Marleen; De Munck, Jan; Van Landuyt, Kirsten; Poitevin, Andre; Lambrechts, Paul; Van Meerbeek, Bart

    2010-04-01

    The aim of this prospective randomized controlled clinical trial was to evaluate the 2-year clinical performance of a self-adhesive resin cement, RelyX Unicem (3M ESPE), used for cementation of ceramic inlays. In addition, the influence of selectively acid etching enamel prior to luting on marginal integrity, inlay integrity, tooth integrity, sensitivity, and complications of the restored teeth was assessed. The hypothesis tested was that there was no significant difference in these criteria between restorations with (Etch) or without prior enamel acid etching (Non-etch). Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group; Etch) or without (=control group; Non-etch) prior enamel etching with phosphoric acid. At baseline, 6 months, 1 year and 2 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. The recall rate at 24 months was 96.6%. Two restorations were clinically unacceptable due to loss of retention, leading to a survival rate of 96.6% (Kaplan-Meier). No significant difference was noted between the experimental group and the control group regarding marginal integrity, inlay integrity, tooth integrity, complications and sensitivity (McNemar, p > 0.05). An obvious deterioration in marginal adaptation was observed after 24 months as only 21.7% (Etch = 23.4%; Non-etch = 20%) of the restorations exhibited an excellent marginal adaptation compared to 70.7% (Etch = 75%; Non-etch = 66.7%) at baseline. In 74.9% of the restorations, small, still clinically acceptable marginal deficiencies were observed (Etch = 76.6%; Non-etch = 73.2%). The self-adhesive resin cement RelyX Unicem showed acceptable clinical behavior after two years of clinical service. Selective enamel etching prior to luting had no significant influence on marginal integrity, inlay integrity, tooth integrity, sensitivity or

  17. A novel posteromedial approach for tibial inlay PCL reconstruction in KDIIIM injuries: avoiding prone patient positioning.

    Science.gov (United States)

    Richter, Dustin; Wascher, Daniel C; Schenck, Robert C

    2014-09-01

    Treatment of traumatic knee dislocations remains controversial and challenging. Current techniques for PCL reconstruction utilize either a transtibial approach with potential risk of vascular injury from drilling toward the popliteal artery or a tibial inlay technique with prone patient positioning, which is cumbersome and adds operative time. We therefore developed a surgical technique using a supine posteromedial approach for PCL tibial inlay reconstruction for the treatment of Schenck KDIIIM (ACL/PCL/medial collateral ligament) knee dislocations. In patients undergoing this technique, we evaluated patient-reported outcome scores, ROM, stability, and complications. Tibial inlay PCL reconstructions were performed through a posteromedial approach with the patient supine, knee flexed, and hip externally rotated, thus avoiding prone patient positioning. The inlay approach uses the interval between the medial head of the gastrocnemius and the pes anserinus (gracilis and semitendinosus), with release of the semimembranosus tendon approximately 1 cm from its insertion on the tibia. Retraction of the medial gastrocnemius and semimembranosus allows access to the posteromedial aspect of the proximal tibia while protecting the neurovascular bundle. All 11 patients sustaining a KDIIIM multiligamentous knee injury treated between 2002 and 2011 with a three-ligament reconstruction received this posteromedial approach. Seven patients were available for complete evaluation, and one completed telephone followup only. Mean followup was 6.0 years (range, 2.0-11.2 years). Clinical evaluation included Lysholm and Tegner activity scores and measurements of ROM and knee laxity. We also recorded complications. Mean Lysholm and Tegner activity scores were 81 and 4.9, respectively, with three patients returning to recreational or competitive sports. Mean knee flexion was 120° (range, 106°-137°); however, two patients had stiffness in flexion, lacking greater than 20° of flexion

  18. Analysis of vector models in quantification of artifacts produced by standard prosthetic inlays in Cone-Beam Computed Tomography (CBCT)--a preliminary study.

    Science.gov (United States)

    Różyło-Kalinowska, Ingrid; Miechowicz, Sławomir; Sarna-Boś, Katarzyna; Borowicz, Janusz; Kalinowski, Paweł

    2014-11-17

    Cone-beam computed tomography (CBCT) is a relatively new, but highly efficient imaging method applied first in dentistry in 1998. However, the quality of the obtained slices depends among other things on artifacts generated by dental restorations as well as orthodontic and prosthetic appliances. The aim of the study was to quantify the artifacts produced by standard prosthetic inlays in CBCT images. The material consisted of 17 standard prosthetic inlays mounted in dental roots embedded in resin. The samples were examined by means of a large field of view CBCT unit, Galileos (Sirona, Germany), at 85 kV and 14 mAs. The analysis was performed using Able 3DDoctor software for data in the CT raster space as well as by means of Materialise Magics software for generated vector models (STL). The masks generated in the raster space included the area of the inlays together with image artifacts. The region of interest (ROI) of the raster space is a set of voxels from a selected range of Hounsfield units (109-3071). Ceramic inlay with zirconium dioxide (Cera Post) as well as epoxy resin inlay including silica fibers enriched with zirconium (Easy Post) produced the most intense artifacts. The smallest image distortions were created by titanium inlays, both passive (Harald Nordin) and active (Flexi Flange). Inlays containing zirconium generated the strongest artifacts, thus leading to the greatest distortions in the CBCT images. Carbon fiber inlay did not considerably affect the image quality.

  19. A comparison of the accuracy of patterns processed from an inlay casting wax, an auto-polymerized resin and a light-cured resin pattern material

    Directory of Open Access Journals (Sweden)

    Praveen Rajagopal

    2012-01-01

    Conclusion: The resin pattern materials studied, undergo a significantly less dimensional change than the inlay waxes on prolonged storage. They would possibly be a better alternative to inlay wax in situations requiring high precision or when delayed investment (more than 1 h of patterns can be expected.

  20. Analysis of Vector Models in Quantification of Artifacts Produced by Standard Prosthetic Inlays in Cone-Beam Computed Tomography (CBCT – a Preliminary Study

    Directory of Open Access Journals (Sweden)

    Ingrid Różyło-Kalinowska

    2014-11-01

    Full Text Available Cone-beam computed tomography (CBCT is a relatively new, but highly efficient imaging method applied first in dentistry in 1998. However, the quality of the obtained slices depends among other things on artifacts generated by dental restorations as well as orthodontic and prosthetic appliances. The aim of the study was to quantify the artifacts produced by standard prosthetic inlays in CBCT images. The material consisted of 17 standard prosthetic inlays mounted in dental roots embedded in resin. The samples were examined by means of a large field of view CBCT unit, Galileos (Sirona, Germany, at 85 kV and 14 mAs. The analysis was performed using Able 3DDoctor software for data in the CT raster space as well as by means of Materialise Magics software for generated vector models (STL. The masks generated in the raster space included the area of the inlays together with image artifacts. The region of interest (ROI of the raster space is a set of voxels from a selected range of Hounsfield units (109-3071. Ceramic inlay with zirconium dioxide (Cera Post as well as epoxy resin inlay including silica fibers enriched with zirconium (Easy Post produced the most intense artifacts. The smallest image distortions were created by titanium inlays, both passive (Harald Nordin and active (Flexi Flange. Inlays containing zirconium generated the strongest artifacts, thus leading to the greatest distortions in the CBCT images. Carbon fiber inlay did not considerably affect the image quality.

  1. High mid-term revision rate after treatment of large, full-thickness cartilage lesions and OA in the patellofemoral joint using a large inlay resurfacing prosthesis

    DEFF Research Database (Denmark)

    Laursen, Jens Ole

    2017-01-01

    pain but high mid-term revision rate after patellofemoral inlay resurfacing using the HemiCAP-Wave® implant. Patellofemoral resurfacing implantation treatment with a large inlay prosthesis can offer temporary treatment for large isolated patellofemoral cartilage lesions or OA in younger patients...

  2. Influence of material selection on the risk of inlay fracture during pre-cementation functional occlusal tapping.

    Science.gov (United States)

    Magne, Pascal; Paranhos, Maria P G; Schlichting, Luís H

    2011-02-01

    To evaluate in vitro the pre-cementation resistance of CAD/CAM inlays subjected to functional occlusal tapping. An extracted tooth model (molar and premolar) with simulated bone and periodontal ligament was used to make a medium-size mesio-occlusal inlay preparation (molar). Immediate dentin sealing was applied to the prepared tooth. The corresponding inlays were fabricated with Cerec either using composite resin (Paradigm MZ100) or ceramic (e.max CAD and Mark II) blocks (n=14). A high marginal ridge was designed in order to generate hyper-occlusion. Pre-cementation occlusal tapping was simulated using closed-loop servo-hydraulics at 2 Hz, starting with a load of 40 N, followed by 80, 120, 160, 200, 240, and 280 N (10 cycles each). All samples were loaded until fracture or to a maximum of 70 cycles. Groups were compared using the life table survival analysis (p=0.016, Bonferroni method). Survival probability was e.max CAD>MZ100>Mark II. None of the specimens survived the 70 cycles except for two e.max CAD inlays (survival: 14%). Material selection has a significant effect on the risk of Cerec inlay fracture during pre-cementation functional occlusal tapping. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Effect of hydrothermal process for inorganic alumina sol on crystal structure of alumina gel

    Directory of Open Access Journals (Sweden)

    K. Yamamura

    2016-09-01

    Full Text Available This paper reports the effect of a hydrothermal process for alumina sol on the crystal structure of alumina gel derived from hydrothermally treated alumina sol to help push forward the development of low temperature synthesis of α-Al2O3. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in the production of a transparent alumina sol. The alumina sol was treated with a hydrothermal process and transformed into an alumina gel film by drying at room temperature. Crystallization of the alumina gel to α-Al2O3 with 900 °C annealing was dominant for a hydrothermal temperature of 100 °C and a hydrothermal time of 60 min, as production of diaspore-like species was promoted with the hydrothermal temperature and time. Excess treatments with hydrothermal processes at higher hydrothermal temperature for longer hydrothermal time prevented the alumina gel from being crystallized to α-Al2O3 because the excess hydrothermal treatments promoted production of boehmite.

  4. Marginal gap, internal fit, and fracture load of leucite-reinforced ceramic inlays fabricated by CEREC inLab and hot-pressed techniques.

    Science.gov (United States)

    Keshvad, Alireza; Hooshmand, Tabassom; Asefzadeh, Farokh; Khalilinejad, Foroogh; Alihemmati, Mohammad; Van Noort, Richard

    2011-10-01

    This in vitro study was designed to evaluate and compare the marginal gap, internal fit, and fracture load of resin-bonded, leucite-reinforced glass ceramic mesio-occlusal-distal (MOD) inlays fabricated by computer-aided design/manufacturing (CAD/CAM) or hot pressing. Fifty caries-free extracted human molars were prepared for standardized MOD inlays. Impressions of each specimen were made and poured using type IV dental stone. Dies were randomly divided into two equal groups. Twenty-five ceramic inlays were fabricated by the hot-pressed technique using IPS Empress leucite-reinforced glass ceramics, and the other 25 ceramic inlays were produced by CAD/CAM technology using ProCAD leucite-reinforced ceramic blocks and CEREC inLab facilities. Inlays were bonded to the teeth using a dual-cured resin cement. The specimens were stored in distilled water at 37°C for 24 hours and then thermocycled for 5000 cycles. The marginal gap measurements were taken with a stereomicroscope. Specimens in each group of inlay systems were randomly divided into two subgroups of 10 and 15 specimens each. Ten specimens in each subgroup were sectioned mesiodistally for evaluation of the internal fit. The fracture load of specimens in the second subgroup (n = 15) of the two inlay systems was determined under compressive load in a universal testing machine. Data were analyzed using Student's t-test at a significance level of p inlays were less than 100 μm; however, the marginal gap for the IPS Empress restorations was significantly higher than that of ProCAD restorations (p inlays (p > 0.05). The leucite-reinforced glass ceramic inlay restorations fabricated by CEREC inLab (CAD/CAM) and the hot-pressed technique provided clinically acceptable marginal and internal fit with comparable fracture loads after luting. © 2011 by The American College of Prosthodontists.

  5. The local strength of individual alumina particles

    Science.gov (United States)

    Pejchal, Václav; Fornabaio, Marta; Žagar, Goran; Mortensen, Andreas

    2017-12-01

    We implement the C-shaped sample test method and micro-cantilever beam testing to measure the local strength of microscopic, low-aspect-ratio ceramic particles, namely high-purity vapor grown α-alumina Sumicorundum® particles 15-30 μm in diameter, known to be attractive reinforcing particles for aluminum. Individual particles are shaped by focused ion beam micromachining so as to probe in tension a portion of the particle surface that is left unaffected by ion-milling. Mechanical testing of C-shaped specimens is done ex-situ using a nanoindentation apparatus, and in the SEM using an in-situ nanomechanical testing system for micro-cantilever beams. The strength is evaluated for each individual specimen using bespoke finite element simulation. Results show that, provided the particle surface is free of readily observable defects such as pores, twins or grain boundaries and their associated grooves, the particles can achieve local strength values that approach those of high-perfection single-crystal alumina whiskers, on the order of 10 GPa, outperforming high-strength nanocrystalline alumina fibers and nano-thick alumina platelets used in bio-inspired composites. It is also shown that by far the most harmful defects are grain boundaries, leading to the general conclusion that alumina particles must be single-crystalline or alternatively nanocrystalline to fully develop their potential as a strong reinforcing phase in composite materials.

  6. Alumina-base plasma-sprayed materials part I: Phase stability of alumina and alumina-chromia

    Science.gov (United States)

    Chráska, P.; Dubsky, J.; Neufuss, K.; Písacka, J.

    1997-09-01

    Aluminum oxide is a relatively cheap, abundant material that is widely used for plasma- spray applications. This material, however, exists in many crystallographic modifications with different properties. In addition, most of these modifications are metastable and cannot be used in applications employed at elevated temperatures. Usually γ, δ, or other phases form after spraying, while α phase (corundum) is often the most desirable phase due to high corrosion resistance and hardness. This paper first reviews the method of α stabilization in the as- sprayed materials offered in literature. Then, as an example, it summarizes the results of an extensive study of chromia additions to alumina. Chromia was chosen because of its complete solid solubility in alumina and its crystal lattice type, which is similar to that of alumina. It was demonstrated that the addition of approximately 20 wt% chromia results in the formation of one solid solution of (Al- Cr)2O3 in the α- modification. Finally, this paper discusses the thermal stability of various alumina phases. Phase change routes of heating for different starting alumina modifications are discussed, and a case study of alumina- chromia is presented. Both types of as-sprayed structures, a mixture of α, δ, and γ phases, and 100% (Al- Cr)2O3 were annealed up to 1300 °C and the phase composition checked. At lower temperatures and shorter holding times, the amount of α phase decreases while another metastable θ phase appears, and the fraction of γ + δ, if present, increases. At temperature above 1100 °C, the amount of α phase increases again.

  7. Reconstruction of an atrophied posterior mandible with the inlay technique and allograft block versus allograft particulate: a case report.

    Science.gov (United States)

    Checchi, Vittorio; Mazzoni, Annalisa; Breschi, Lorenzo; Felice, Pietro

    2015-01-01

    This case report describes the bilateral reconstruction of a severely atrophic posterior mandible in a 30-year-old woman using allograft block versus particulate grafting in the inlay technique. Three months later, four dental implants were placed and bone core biopsy specimens were taken for histologic evaluation. During implant placement, the grafted sites were stable with good clinical osseointegration. The histologic analysis showed the presence of compact bone revealing areas of demarcation between grafted bone, newly formed bone, and bone-regenerated areas. Allografts might serve as an alternative to autogenous and heterologous grafting in posterior mandible augmentation using the inlay technique.

  8. Dielectric Performance of a High Purity HTCC Alumina at High Temperatures - a Comparison Study with Other Polycrystalline Alumina

    Science.gov (United States)

    Chen, Liangyu

    2014-01-01

    A very high purity (99.99+%) high temperature co-fired ceramic (HTCC) alumina has recently become commercially available. The raw material of this HTCC alumina is very different from conventional HTCC alumina, and more importantly there is no glass additive in this alumina material for co-firing processing. Previously, selected HTCC and LTCC (low temperature co-fired ceramic) alumina materials were evaluated at high temperatures as dielectric and compared to a regularly sintered 96% polycrystalline alumina (96% Al2O3), where 96% alumina was used as the benchmark. A prototype packaging system based on regular 96% alumina with Au thickfilm metallization successfully facilitated long term testing of high temperature silicon carbide (SiC) electronic devices for over 10,000 hours at 500 C. In order to evaluate this new high purity HTCC alumina for possible high temperature packaging applications, the dielectric properties of this HTCC alumina substrate were measured and compared with those of 96% alumina and a previously tested LTCC alumina from room temperature to 550 C at frequencies of 120 Hz, 1 KHz, 10 KHz, 100 KHz, and 1 MHz. A parallel-plate capacitive device with dielectric of the HTCC alumina and precious metal electrodes were used for measurements of the dielectric constant and dielectric loss of the co-fired alumina material in the temperature and frequency ranges. The capacitance and AC parallel conductance of the capacitive device were directly measured by an AC impedance meter, and the dielectric constant and parallel AC conductivity of the dielectric were calculated from the capacitance and conductance measurement results. The temperature and frequency dependent dielectric constant, AC conductivity, and dissipation factor of the HTCC alumina substrate are presented and compared to those of 96% alumina and a selected LTCC alumina. Other technical advantages of this new co-fired material for possible high packaging applications are also discussed.

  9. Challenges and Strategies in the Synthesis of Mesoporous Alumina Powders and Hierarchical Alumina Monoliths

    Directory of Open Access Journals (Sweden)

    Anne Galarneau

    2012-02-01

    Full Text Available A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous γ-Al2O3 is presented. The resulting mesoporous alumina materials feature high surface areas (400 m2 g−1, large pore volumes (0.8 mL g−1 and the ��-Al2O3 phase is obtained at low temperature (500 °C. The main advantages and drawbacks of different preparations of mesoporous alumina materials exhibiting high specific surface areas and large pore volumes such as surfactant-nanostructured alumina, sol-gel methods and hierarchically macro-/mesoporous alumina monoliths have been analyzed and compared. The most reproducible synthesis of mesoporous alumina are given. Evaporation-Induced Self-Assembly (EISA is the sole method to lead to nanostructured mesoporous alumina by direct templating, but it is a difficult method to scale-up. Alumina featuring macro- and mesoporosity in monolithic shape is a very promising material for in flow applications; an optimized synthesis is described.

  10. Crack shielding degradation in alumina during cyclic fatigue

    Energy Technology Data Exchange (ETDEWEB)

    El Attaoui, H.; Saadaoui, M. [LERSIM, Rabat (Morocco); INSA de Lyon, Villeurbanne (France). GEMPPM; Chevalier, J.; Fantozzi, G. [INSA de Lyon, Villeurbanne (France). GEMPPM

    2002-07-01

    R curve measurements before and after cyclic fatigue were performed on SENB specimens of coarse grain alumina to investigate fatigue effect. A significant drop of the crack growth resistance was observed after cyclic loading which could be associated to a decrease of the shielding effect due to bridging degradation. No variation was observed on the amount of degradation as the number of cycles increased for a maximum applied load, K{sub max} of 50% of the K{sub R} value before cyclic loading, K{sub f}, whereas an increase was observed for K{sub max}/K{sub f} = 0.7, when the critical number of cycles corresponding to failure was approached. (orig.)

  11. Comparison of FDA safety and efficacy data for KAMRA and Raindrop corneal inlays

    Directory of Open Access Journals (Sweden)

    Majid Moshirfar

    2017-09-01

    Full Text Available AIM: To provide a side-by-side analysis of the summary of safety and effectiveness data (SSED submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia. METHODS: SSED reports submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity (CDVA, adverse event rates, induction of astigmatism, retention of contrast sensitivity, stability of manifest refractive spherical equivalent (MRSE, and achieved monocular uncorrected near visual acuity (UNVA at 24mo. RESULTS: Totally 442/508 of KAMRA patients and 344/373 Raindrop patients remained enrolled in the clinical trials at 24mo. The proportion of KAMRA and Raindrop patients who lost ≥2 lines of CDVA at 24mo was 3.4% and 1%, respectively. The adverse event rate was comparable between the devices. No significant inductions of astigmatism were noted. Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization. Totally 87% of KAMRA and 98% of Raindrop patients attained a monocular UNVA of J5 (20/40 or better at 24mo, 28% of KAMRA and 67% of Raindrop patients attained a monocular UNVA of J1 (20/20 or better at 24mo. CONCLUSION: Both devices can be considered safe and effective, however, the results of corneal inlay implantation are mixed, and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays. Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article.

  12. Comparison of FDA safety and efficacy data for KAMRA and Raindrop corneal inlays

    Science.gov (United States)

    Moshirfar, Majid; Desautels, Jordan D; Wallace, Ryan T; Koen, Nicholas; Hoopes, Phillip C.

    2017-01-01

    AIM To provide a side-by-side analysis of the summary of safety and effectiveness data (SSED) submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia. METHODS SSED reports submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity (CDVA), adverse event rates, induction of astigmatism, retention of contrast sensitivity, stability of manifest refractive spherical equivalent (MRSE), and achieved monocular uncorrected near visual acuity (UNVA) at 24mo. RESULTS Totally 442/508 of KAMRA patients and 344/373 Raindrop patients remained enrolled in the clinical trials at 24mo. The proportion of KAMRA and Raindrop patients who lost ≥2 lines of CDVA at 24mo was 3.4% and 1%, respectively. The adverse event rate was comparable between the devices. No significant inductions of astigmatism were noted. Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization. Totally 87% of KAMRA and 98% of Raindrop patients attained a monocular UNVA of J5 (20/40) or better at 24mo, 28% of KAMRA and 67% of Raindrop patients attained a monocular UNVA of J1 (20/20) or better at 24mo. CONCLUSION Both devices can be considered safe and effective, however, the results of corneal inlay implantation are mixed, and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays. Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article. PMID:28944206

  13. Considerations for Altering Preparation Designs of Porcelain Inlay/Onlay Restorations for Nonvital Teeth.

    Science.gov (United States)

    Homsy, Foudda; Eid, Rita; El Ghoul, Wiam; Chidiac, Jose Johann

    2015-08-01

    The aim of this study was to compare all ceramic inlay/onlay survival rates in vital and nonvital teeth having the same cavity design. Filling the pulp chamber with ceramic materials or not was also discussed. Ceramic class II inlays/onlays were made on 11 premolars and 30 molars: 14 vital, 27 endodontically treated. The same tooth preparation design was performed on vital and nonvital teeth: In nonvital teeth the pulp chambers were covered by a glass ionomer cement until the pulpal floor depths were between 2 and 2.5 mm, more likely similar to the vital teeth preparations. In vital teeth, glass ionomer was used as a liner to achieve pulpal floor depths between 2 and 2.5 mm when needed. The restorations were assessed (at baseline, 6 months, 1 and 2 years) according to three criteria: marginal discoloration, marginal integrity, and fracture of teeth/restorations, consistent with United States Public Health Service (USPHS) criteria. Eight teeth (19%) showed minor marginal discolorations, while three molars (7%) had loss of marginal integrity. These margins were adjusted using rubber polishing cups and were then judged clinically acceptable. From these three molars, one was vital and two were endodontically treated. No fracture of teeth or restorations was observed. Chi square and exact probability tests were used. There was no statistical difference between vital and nonvital teeth (p = 0.719 chi-squared and Fisher) or between premolars and molars (p = 0.564 chi-squared; 1.000, Fisher). Within the limitations of this study there was no difference for the same inlay/onlay cavity design between vital and nonvital teeth. In nonvital teeth, it seems that filling the pulp chamber with a ceramic core material is not important. Long-term observation periods are needed to reinforce the clinical behavior outcome. © 2015 by the American College of Prosthodontists.

  14. Pt/Au nanoalloy supported on alumina and chlorided alumina: DFT and experimental analysis

    Science.gov (United States)

    Sharifi, N.; Falamaki, C.; Ghorbanzadeh Ahangari, M.

    2018-04-01

    Density functional theory (DFT) was used to explore the adsorption of Pt/Au nanoalloy onto a pure and chlorided γ-Al2O3(110) surface, which has been applied in numerous catalytic reactions. First, we considered the adsorption properties of Pt clusters (n ≤ 5) onto the Al2O3(110) surface to determine the most stable Pt cluster on alumina surface in reforming processes. After full structural relaxations of Pt clusters at various configurations on alumina, our computed results expressed that the minimum binding energy (‑5.67 eV) is accrued for Pt4 cluster and the distance between the nearest Pt atom in the cluster to the alumina surface is equal to 1.13 Å. Then, we investigated the binding energies, geometries, and electronic properties of adsorbed Aun clusters (n ≤ 6) on the γ-Al2O3(110) surface. Our studied showed that Au5 was the most thermodynamically stable structure on γ-Al2O3. Finally, we inspected these properties for adsorbed Au clusters onto the Pt4-decorated alumina (Aun/Pt4-alumina) system. The binding energy of the Au4/Pt4-alumina system was ‑5.01 eV, and the distance between Au4 cluster and Pt4-alumina was 1.33 Å. The Au4/Pt4alumina system was found to be the most stable nanometer-sized catalyst design. At last, our first-principles calculations predicted that the best position of embedment Cl on the Au4/Pt4-alumina.

  15. Synthesis and characterization of alumina precursor and alumina to be used as nano composite; Sintese e caracterizacao de precursores de alumina e alumina para uso em nanocompositos

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, M.L.P., E-mail: malu@sorocaba.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil); Santos, H. Souza [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Santos, P. Souza [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica

    2009-07-01

    With the evolution of nanomaterials technology, mainly in the 90s, it was possible to observe produced composites with alumina matrix and nanomaterial as reinforcing materials. It results in a significant improvement of mechanical proprieties of these composites. Thenceforth the study of synthesis and characterization of nanostructured materials has attracted great scientific interest. In this perspective, the aim of this work is to present an experimental procedure to obtain nordstrandite (aluminum hydroxide) with nanometric dimensions. Nordstrandite synthesis, obtained by the reaction of slightly amalgamated aluminum foil with aqueous ethylene glycol, which allows the control of the size of crystal produced. This control could be confirmed by X-Ray Diffraction and Electron Microscopy. Thermal transformation study is also presented. This study allowed the identification of transition aluminas that have potential to produce nanometric aluminas. (author)

  16. Electrochemically produced alumina as TL detector

    International Nuclear Information System (INIS)

    Osvay, M.

    1996-01-01

    The goal of this work was to compare the TL properties of various electrochemically produced alumina layers (E-AIO) in order to investigate the effect of the electrolyte and the Mg content on the alloys. It has been found that the TL sensitivity of oxidised layers is more influenced by the type of electrolyte, than by the composition of alloy. Hard oxide layer evolved in reduction electrolyte has rather different character compared to other alumina production investigated. The effect of reducing media seems to be very important during preparation of alumina layer. One of the advantages properties of E-AIO is, that it serve a promising method to increase the measuring range of TL method above 10 kGy as well. (author)

  17. Beta-alumina solid electrolyte separators

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, J.H.; Stead, R.J.

    1989-06-14

    A method of making a composite beta-alumina artifact such as a separator tube for an electrochemical cell, comprising two beta-alumina portions which are sealed together in a sealing zone, namely an inner portion and an outer portion which extends peripherally around the inner portion and embraces it in the sealing zone, comprises pressing the inner and outer portions from powders which, when finally sintered, shrink and form integral beta-alumina artifacts. The portions are made so that the outer portion undergoes a greater degree of shrinkage during sintering than the inner portion and the portions are pressed so that the spacing between the portions where the outer portion extends around and embraces the inner portion is such that, upon sintering, the outer portion shrinks on to the inner portion to provide a hermetic peripheral seal between the portions. (author).

  18. Hydrogen diffusion in Pb β''-alumina

    International Nuclear Information System (INIS)

    Bates, J.B.; Dudney, N.J.; Wang, J.C.

    1985-01-01

    The mobile Na + ions in Na β''-alumina can be completely exchanged with Pb 2+ ions by treatment in molten PbCl 2 . When this exchange was carried out in the presence of air, protons in the form of OH - were introduced into the conduction layers along with lead ions. Although the concentration of OH - was low, on the order of 5 x 10 -3 per formula unit of Pb/sub 0.84/Mg/sub 0.67/Al/sub 10.33/O_1_7, the distribution of OH - after ion exchange indicated that the proton mobility in Pb β''-alumina is high. The potential use of Pb β''-alumina as a fast proton conductor that is stable at 400 0 C motivated further studies of hydrogen diffusion. In this report, the results of tracer diffusion measurements by isotope exchange will be presented

  19. Blocking of grain reorientation in self-doped alumina materials

    International Nuclear Information System (INIS)

    Suarez, M.; Fernandez, A.; Menendez, J.L.; Ramirez-Rico, J.; Torrecillas, R.

    2011-01-01

    Alumina nanoparticles 10-20 nm in diameter were nucleated on alumina particles, 150 nm average diameter, by a colloidal route followed by calcination. It is shown that after sintering, the final grain size is up to 20% smaller due to the addition of the alumina nanoparticles. Electron backscattered diffraction analysis shows that whereas a correlation in the relative crystalline orientations between neighbouring grains exists in the pure materials, the addition of alumina nanoparticles results in a random crystalline orientation.

  20. All-ceramic inlay-retained fixed dental prostheses: An update.

    Science.gov (United States)

    Chaar, M Sad; Passia, Nicole; Kern, Matthias

    2015-10-01

    Inlay-retained fixed dental prostheses (IRFDPs) represent a minimally invasive alternative to conventional fixed dental prostheses (FDPs) to replace single posterior missing teeth. The aim of the present review article is to assess the clinical outcome of different IRFDPs in order to derive recommendations regarding their clinical application. Hence, it is essential to highlight important factors that influence the longevity and success of IRFDPs, such as treatment plan, appropriate case selection with proper indications, as well as tooth preparation. Furthermore, a good understanding of bonding technologies and awareness of pretreatment procedures for different materials are indispensable for the long-term success of IRFDPs.

  1. The influence of elastic modulus of inlay materials on stress distribution and fracture of premolars.

    Science.gov (United States)

    Costa, Akf; Xavier, Ta; Noritomi, Py; Saavedra, G; Borges, Als

    2014-01-01

    SUMMARY The purpose of this study was to evaluate the influence the width of the occlusal isthmus and inlay material had on the stress distribution, displacement, and fracture resistance of upper human premolars. For this in vitro test, 35 intact upper premolars (UPM) were selected and five were kept intact for the control group (group I). The remaining 30 were divided into two experimental groups (n=15) according to the width of isthmus: conservative (CP) and extensive preparation (EP), one third and more than two thirds of cuspal distance, respectively. Five teeth from each experimental group were left without restoration for negative controls (CPnc and EPnc), and the remaining 10 in each group were subdivided according to the inlay material (resin or ceramic): group CPr, CP + indirect resin; group CPc, CP + ceramic; group EPr, EP + indirect resin; and group EPc, EP + ceramic. The cemented inlays were loaded in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed with stereomicroscopy, and the values of the fracture resistance evaluated by analysis of variance and Tukey test. For the finite element analyses, an average UPM for each group was modeled in Rhinoceros CAD software and imported to Ansys 13.0. An average of 320,000 tetrahedral elements and 540,000 nodes for the seven models were performed using the same experimental simulation setup for each. The models were constrained on the base, and a displacement of 0.02 mm was applied to keep a linear behavior for the analysis. A von Mises stress and total displacement fields were used for the coherence test and the maximum principal stress fields were used for mechanical behavior comparisons. Group I (161.73 ± 22.94) showed a significantly higher mean value than the other experimental groups (EPc: 103.55 ± 15.84; CPc: 94.38 ± 12.35; CPr: 90.31 ± 6.10; EPr: 65.42 ± 10.15; CPnc: 65.46 ± 5.37; EPnc: 58.08 ± 9.62). The stress distribution was

  2. Fabrication of Ceramic Matrix Composite Tubes Using a Porous Mullite/Alumina Matrix and Alumina/Mullite Fiber

    National Research Council Canada - National Science Library

    Radsick, Timothy

    2001-01-01

    ... or from inadequate oxide-based ones. A porous mullite/alumina matrix combined with alumina/mullite fiber reinforcement eliminates the need for an interface coating while producing a strong, tough and oxidation resistant composite...

  3. Synthesis of Gamma-Alumina from Kankara Kaolin as Potential ...

    African Journals Online (AJOL)

    Engr Solomn Gajere

    Gamma-alumina was produced at 850°C with 3 h soaking time, having specific surface area of 166 m2/g. The weight percent of Al2O3 ... conversion and gasoline octane number. (Scherzer, 1993). Among the different alumina ... common method of producing alumina is by the hydrothermal technique and the reaction takes.

  4. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white, odorless...

  5. Characterization of alumina using small angle neutron scattering (SANS)

    International Nuclear Information System (INIS)

    Megat Harun Al Rashidn Megat Ahmad; Abdul Aziz Mohamed; Azmi Ibrahim; Che Seman Mahmood; Edy Giri Rachman Putra; Muhammad Rawi Muhammad Zin; Razali Kassim; Rafhayudi Jamro

    2007-01-01

    Alumina powder was synthesized from an aluminium precursor and studied using small angle neutron scattering (SANS) technique and complemented with transmission electron microscope (TEM). XRD measurement confirmed that the alumina produced was high purity and highly crystalline αphase. SANS examination indicates the formation of mass fractals microstructures with fractal dimension of about 2.8 on the alumina powder. (Author)

  6. Ionic and molecular transport in beta- and beta''-alumina

    International Nuclear Information System (INIS)

    Bates, J.B.

    1984-03-01

    Investigations of rapid transport of cations and water molecules in the β- and β''-alumina family of superionic conductors are reviewed. Particular topics that are discussed include the Haven ratio and mixed-ion effects in β-alumina, and the influence of superlattice ordering on ionic transport in β''-alumina

  7. Tritium compatibility of alumina and Fosterite

    Energy Technology Data Exchange (ETDEWEB)

    Coffin, D.O.

    1979-09-01

    Many pressure measurements are required to control processing of the fuel gases associated with fusion power reactors. Since most pressure transducers respond to changes in pressure sensitive electrical parameters, insulators will be required to withstand chronic exposures to concentrated tritium. For this investigation samples of alumina and Fosterite were exposed to concentrated tritium gas for 11 weeks. Gas phase impurities were then analyzed for clues that would indicate decomposition of the exposed materials. The only gaseous impurity resulting from these tritium exposures was tritio-methane, which is always produced when tritium is stored in stainless steel containers. There was no evidence that either alumina or Fosterite decomposed in the presence of tritium.

  8. Studies of alumina additions in zirconia - magnesia

    International Nuclear Information System (INIS)

    Muccillo, R.

    1987-01-01

    Ionic conductivity measurements have been carried out in the 500 0 C - 1000 0 C temperature range in Mg - PSZ (Partially Stabilized Zirconia) with 0.5 to 10 mol % alumina additions. All specimens were prepared by pressing followed by pre - and sintering at 1000 0 C/2h and1450 0 C/4h, respectively. Thermal histerysis of the ionic conductivity have been detected, probably due to phase changes in the Mg-PSZ samples. The results show that alumina additions up to 2.1% enhances densification with no major variations in electrical resistivity values. (Author) [pt

  9. Study on alumina-alumina brazing for application in vacuum chambers of proton synchrotron

    International Nuclear Information System (INIS)

    Yadav, D.P.; Kaul, R.; Ganesh, P.; Shiroman, Ram; Tiwari, Pragya; Sridhar, R.; Kukreja, L.M.

    2013-01-01

    The paper describes an experimental study to standardize vacuum brazing process to obtain satisfactory high purity alumina brazed joints for application in rapid cycle proton synchrotron machine. Two different brazing routes, adopted for making alumina-alumina brazed joints, included (i) multi-step Mo-Mn metallization and brazing with BVAg-8 alloy and (ii) advanced single-step active brazing with CuSil-ABA alloy. Brazed alumina specimens, prepared by both the routes, yielded ultra high vacuum compatible, helium leak tight and bakeable joints. Active-brazed specimens exhibited satisfactory strength values in tensile and four-point bend tests. Metallized-brazed specimens, although exhibited relatively lower tensile strength than the targeted value, displayed satisfactory flexural strength in four-point bend test. The results of the study demonstrated that active brazing is the simple and cost effective alternative to conventional metallization route for producing satisfactory brazed joints for application in rapid cycle proton synchrotron machine. (author)

  10. Thermal Conductivity of Alumina-Toughened Zirconia Composites

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dong-Ming

    2003-01-01

    10-mol% yttria-stabilized zirconia (10YSZ)-alumina composites containing 0 to 30 mol% alumina were fabricated by hot pressing at 1500 C in vacuum. Thermal conductivity of the composites, determined at various temperatures using a steady-state laser heat flux technique, increased with increase in alumina content. Composites containing 0, 5, and 10-mol% alumina did not show any change in thermal conductivity with temperature. However, those containing 20 and 30-mol% alumina showed a decrease in thermal conductivity with increase in temperature. The measured values of thermal conductivity were in good agreement with those calculated from simple rule of mixtures.

  11. The effect of box preparation on the strength of glass fiber–reinforced composite inlay-retained fixed partial dentures

    NARCIS (Netherlands)

    Özcan, Mutlu; Breuklander, Marijn H.; Vallittu, Pekka K.

    2005-01-01

    Statement of problem. Nonstandardized box dimensions for inlay-retained fixed partial dentures (FPDs) may result in uneven distribution of the forces on the connector region of such restorations. Purpose. The objective of this in vitro study was to evaluate the effect of box dimensions on the

  12. The effect of box preparation on the strength of glass fiber-reinforced composite inlay-retained fixed partial dentures

    NARCIS (Netherlands)

    Ozcan, M; Breuklander, MH; Vallittu, PK

    Statement of problem. Nonstandardized box dimensions for inlay-retained fixed partial dentures (FPDs) may result in uneven distribution of the forces on the connector region of such restorations. Purpose. The objective of this in vitro study was to evaluate the effect of box dimensions on the

  13. Treatment of osteochondral defects of the talus with a metal resurfacing inlay implant after failed previous surgery: a prospective study

    NARCIS (Netherlands)

    van Bergen, C. J. A.; van Eekeren, I. C. M.; Reilingh, M. L.; Sierevelt, I. N.; van Dijk, C. N.

    2013-01-01

    We have evaluated the clinical effectiveness of a metal resurfacing inlay implant for osteochondral defects of the medial talar dome after failed previous surgical treatment. We prospectively studied 20 consecutive patients with a mean age of 38 years (20 to 60), for a mean of three years (2 to 5)

  14. Experimental Comparison of Cranial Particulate Bone Graft, rhBMP-2, and Split Cranial Bone Graft for Inlay Cranioplasty.

    Science.gov (United States)

    Hassanein, Aladdin H; Couto, Rafael A; Kurek, Kyle C; Rogers, Gary F; Mulliken, John B; Greene, Arin K

    2013-05-01

    Background :  Particulate bone graft and recombinant human bone morphogenetic protein-2 (rhBMP-2) are options for inlay cranioplasty in children who have not developed a diploic space. The purpose of this study was to determine whether particulate bone graft or rhBMP-2 has superior efficacy for inlay cranioplasty and to compare these substances to split cranial bone. Methods :  A 17 mm × 17 mm critical-sized defect was made in the parietal bones of 22 rabbits and managed in four ways: Group I (no implant; n=5), Group II (particulate bone graft; n=5), Group III (rhBMP-2; n=7), and Group IV (split cranial bone graft; n=5). Animals underwent microcomputed tomography and histologic analysis 16 weeks after cranioplasty. Results :  Defects without an implant (Group I) demonstrated inferior ossification (41.4%; interquartile range [IQR], 28.9% to 42.5%) compared to those treated with particulate bone graft (Group II: 99.5%; IQR, 97.8% to 100%), rhBMP-2 (Group III: 99.6%; IQR, 99.5% to 100%), or split cranial bone (Group IV: 100%) (P inlay calvarial defect areas equally, although the thickness of bone healed with rhBMP-2 is inferior. Clinically, particulate bone graft or split cranial bone graft may be superior to rhBMP-2 for inlay cranioplasty.

  15. A comparative mechanical and bone remodelling study of all-ceramic posterior inlay and onlay fixed partial dentures.

    Science.gov (United States)

    Field, Clarice; Li, Qing; Li, Wei; Thompson, Mark; Swain, Michael

    2012-01-01

    Comparative studies of bone remodelling and mechanical stresses between inlay and onlay fixed partial dentures (FPD) are rather limited. The purpose of this paper was to evaluate the biological consequence in posterior mandibular bone and the mechanical responses in these two different prosthetic configurations. Three-dimensional (3D) finite element analysis (FEA) models are created to explore the mechanical responses for the inlay and onlay preparations within the same oral environment. Strain induced bone remodelling was simulated under mastication. The remodelling adopted herein relates the strain in the bone to the change of Hounsfield Unit (HU) value in proportion to the surface area density (SAD) of bony morphology, which allows directly correlating to clinical computerised tomography (CT) data. The results show that both FPD designs exhibit a similar resultant change in bone mineral density (BMD) though the onlay configuration leads to a more uniform distribution of bone density. The inlay design results in higher mechanical stresses whilst allowing preservation of healthy tooth structure. This study provides an effective means to further clinical assessment and investigation into biomechanical responses and long-term restorative outcome with different FPD designs. Quantifying in vivo stress distributions associated with inlay/onlay FPDs can further supplement clinical investigations into prosthetic durability, FPD preparation techniques (i.e., taper angles, material development), consequent stress distributions and the ongoing biomechanical responses of mandibular bone. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Effect of proximal box elevation with resin composite on marginal quality of resin composite inlays in vitro.

    Science.gov (United States)

    Roggendorf, Matthias J; Krämer, Norbert; Dippold, Christoph; Vosen, Vera E; Naumann, Michael; Jablonski-Momeni, Anahita; Frankenberger, Roland

    2012-12-01

    To evaluate marginal quality and resin-resin transition of lab made resin composite inlays in deep proximal cavities with and without 3 mm proximal box elevation (PBE) using resin composites before and after thermo-mechanical loading (TML). MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 40 extracted human third molars. Proximal boxes ending in dentine were elevated 3 mm with different resin composites (G-Cem, Maxcem Elite as self-adhesive resin cements and Clearfil Majesty Posterior as restorative resin composite in one or three layers bonded with AdheSE), or left untreated. Clearfil Majesty Posterior inlays were luted with Syntac and Variolink II (n = 8). Marginal quality as well as the PBE-composite inlay interface was analyzed under an SEM using epoxy resin replicas before and after thermomechanical loading (100,000 × 50 N and 2500 thermocylces between +5 °C and +55 °C). Bonding resin composite inlays directly to dentine showed similar amounts of gap-free margins in dentine compared to PBE applied in three consecutive layers (p > 0.05). The groups with self-adhesive resin cements for PBE exhibited significantly more gaps in dentine (p < 0.05). With layered resin composite, PBE is effective in indirect resin composite bonding to deep proximal boxes. Self-adhesive resin cements are not suitable for this indication. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Fracture behavior of inlay and onlay fixed partial dentures - An in-vitro experimental and XFEM modeling study.

    Science.gov (United States)

    Zhang, Zhongpu; Thompson, Mark; Field, Clarice; Li, Wei; Li, Qing; Swain, Michael V

    2016-06-01

    This study aimed to explore the "sensitivity" of the fracture load and initiation site to loading position on the central occlusal surface of a pontic tooth for both all-ceramic inlay retained and onlay supported partial denture systems. Three dimensional (3D) finite element (FE) inlay retained and onlay supported partial denture models were established for simulating crack initiation and propagation by using the eXtended Finite Element Method (XFEM). The models were subjected to a mastication force up to 500N on the central fossa of the pontic. The loading position was varied to investigate its influence on fracture load and crack path. Small perturbation of the loading position caused the fracture load and crack pattern to vary considerably. For the inlay fixed partial dentures (FPDs), the fracture origins changed from the bucco-gingival aspect of the molar embrasure to the premolar embrasure when the indenter force location is slightly shifted from the mesial to distal side. In contrast, for onlay FPDs, cracking initiated from bucco-gingival aspect of the premolar embrasure when the indenter is slightly shifted to the buccal side and from molar embrasure when the indenter is shifted to the lingual side. The fracture load and cracking path were found to be very sensitive to loading position in the all-ceramic inlay and onlay FPDs. The study provides a basis for improved understanding on the role of localized contact loading of the cusp surface in all-ceramic FPDs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Effects of oxalate desensitizer with different resin cement-retained indirect composite inlays on fracture resistance of teeth.

    Science.gov (United States)

    Shafiei, Fereshteh; Alavi, Ali Asghar; Karimi, Fatemeh; Ansarifard, Elham

    2013-06-01

    This study investigated whether the tubular occluding effect of oxalate desensitizer (OX) during adhesive cementation (three resin cements) influenced fracture resistance of teeth restored with adhesive inlays. Ninety intact maxillary premolars were randomly divided into 9 groups of 10 each. The two control groups were Gr 1, intact teeth and Gr 2, mesio-occlusodistal preparation only. In six experimental groups, the composite inlays were cemented with ED Primer II/Panavia F 2.0, Excite DSC/Variolink II, and One-Step Plus/Duolink according to manufacturers' instructions (Groups 3, 5, and 7, respectively) or with OX during cementation (Groups 4, 6, and 8, respectively). In Group 9, inlays were cemented with a resin cement without adhesive system. After thermocycling, fracture strength was tested. The data were analyzed using two-way and one-way ANOVA and LSD post hoc tests (α = 0.05). Fracture resistance of the six groups were significantly affected by OX (p = 0.002) but not by the resin cement type (p > 0.05). The interaction of the two factors was statistically significant (p = 0.052). A statistically significant difference between all groups was found (p inlay cemented with Panavia F2.0 and Variolink II, but it had no significant effect when cemented with Duolink. © 2012 by the American College of Prosthodontists.

  19. Comparison of fracture resistance of teeth restored with ceramic inlay and resin composite: An in vitro study

    Directory of Open Access Journals (Sweden)

    Priti D Desai

    2011-01-01

    Conclusion: The fracture resistant strength of teeth restored with ceramic inlay was comparable to that of the normal intact teeth or slightly higher, while teeth restored with direct composite resin restoration showed less fracture resistant strength than that of the normal teeth.

  20. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Perdriau, Sebastien; ten Brink, Gert; Kooi, Bart J.; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    An efficient route to stabilize alumina mesophases derived from evaporation-induced self-assembly is reported after investigating various aspects in-depth: influence of the solvent (EtOH, s-BuOH, and t-BuOH) on the textural and structural properties of the mesophases based on aluminum

  1. SANS investigation of nanoporous alumina membranes

    Czech Academy of Sciences Publication Activity Database

    Ryukhtin, Vasyl; Šaroun, Jan; Turkevych, I.

    -, č. 6 (2007), s. 35-36 ISSN 0344-9629 R&D Projects: GA ČR(CZ) GP202/06/P198 Institutional research plan: CEZ:AV0Z10480505 Keywords : nanopor * alumina membrane * netron scattering Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Microleakage of inlay ceramic systems luted with self-adhesive resin cements.

    Science.gov (United States)

    Uludag, Bulent; Yucedag, Elif; Sahin, Volkan

    2014-12-01

    To evaluate the microleakage of Cerec 3, IPS e.max Press, and Turkom-Cera inlays cemented with three self-adhesive resin cements. Ninety standardized class III MOD cavities were prepared in intact human mandibular third molars. Ceramic inlays were fabricated according to the manufacturer's instructions and were cemented using three self-adhesive resin cements (RelyX Unicem, Smartcem 2, and SpeedCEM). The specimens were stored in distilled water at 37°C for 24 h and subjected to 1000 thermocycles in water between 5°C and 55°C with a dwell time of 30 s. Subsequently, the specimens were subjected to 100,000 cycles of mechanical loading of 50 N at 1.6 Hz in 37°C water. The specimens were immersed in 0.5% basic fuchsine for 24 h and were sectioned using a low-speed diamond blade. The percentage of dye leakage at the tooth/restoration interface was measured and compared by Kruskal-Wallis tests with Bonferonni correction and Mann-Whitney U-tests at a significance level of pinlays (p<0.05). Regardless of the ceramic system and self-adhesive resin cement used, dentin margins were associated with higher microleakage than enamel margins.

  3. Comparison of binocular through-focus visual acuity with monovision and a small aperture inlay

    Science.gov (United States)

    Schwarz, Christina; Manzanera, Silvestre; Prieto, Pedro M.; Fernández, Enrique J.; Artal, Pablo

    2014-01-01

    Corneal small aperture inlays provide extended depth of focus as a solution to presbyopia. As this procedure is becoming more popular, it is interesting to compare its performance with traditional approaches, such as monovision. Here, binocular visual acuity was measured as a function of object vergence in three subjects by using a binocular adaptive optics vision analyzer. Visual acuity was measured at two luminance levels (photopic and mesopic) under several optical conditions: 1) natural vision (4 mm pupils, best corrected distance vision), 2) pure-defocus monovision ( + 1.25 D add in the nondominant eye), 3) small aperture monovision (1.6 mm pupil in the nondominant eye), and 4) combined small aperture and defocus monovision (1.6 mm pupil and a + 0.75 D add in the nondominant eye). Visual simulations of a small aperture corneal inlay suggest that the device extends DOF as effectively as traditional monovision in photopic light, in both cases at the cost of binocular summation. However, individual factors, such as aperture centration or sensitivity to mesopic conditions should be considered to assure adequate visual outcomes. PMID:25360355

  4. Marginal Adaptation and Microleakeage of Directly and Indirectly Made Fiber Reinforced Composite Inlays

    Science.gov (United States)

    Ovul, Kumbuloglu; Arzu, Tezvergil-Mutluay; Ahmet, Saracoglu; Lippo VJ, Lassila; Pekka K, Vallittu

    2011-01-01

    Aim: This study evaluated in vitro microleakage of inlays made by direct or indirect techique with or without fiber reinforced composite (FRC) substructure. Materials and Methods: Standardized mesio-occlusal cavities were prepared and restored using direct-technique with composite resin only or FRC-composite resin, and indirect technique with laboratory composite only or FRC-laboratory composite resin. After thermocycling, teeth were immersed in basic fuchsin dye, sectioned and examined under a stereo-microscope (x40). Results: No differences of cement thickness and dye penetration were found in gingival area (p>0.05), whereas microleakage revealed statistical differences between groups (p=0.02) in occlusal area, where FRC-groups had lower microleakage than composite restorations. Thickness of cement layer did not show significant difference between groups with indirect technique (p>0.05). Conclusion: The present study suggests that insertion of FRC substructure to the inlay cavity by direct composite filling technique does not increase the marginal leakage compared to that of cementing indirectly made restotorations by composite resin luting cement. Clinical Significance: On the basis of the results of this in vitro study, the use of direct FRC technique might be an effective way to decrease the marginal leakage. PMID:21566717

  5. Development of an i-line attenuated phase shift process for dual inlay interconnect lithography

    Science.gov (United States)

    Sturtevant, John L.; Ho, Benjamin C. P.; Geiszler, Vincent C.; Herrick, Matthew T.; King, Charles F.; Carter, Russell L.; Roman, Bernard J.; Litt, Lloyd C.; Smith, Brad; Strozewski, Kirk J.

    2000-06-01

    The transition from aluminum/oxide to copper/low-k dielectric interconnect technology involves a variety of fundamental changes in the back-end manufacturing process. The most attractive patterning strategy involves the use of a so-called dual inlay approach, which offers lower fabrication costs by the elimination of one inter-level dielectric (ILD) deposition and polish sequence per metal layer. In this paper, the lithographic challenges for dual inlay, including thin-film interference effect, resist bulk effect, and optical proximity effects are reviewed. The use of attenuated phase shift (aPSM) reticles for patterning vias and trenches was investigated, and shown to provide adequate process margin by optimizing the photoresist and exposure tool parameters. Our results indicate that using appropriately sized attenuated phase shift technique increases the photospeed considerably and simultaneously improves the common process window with sufficient sidelobe suppression margin. The cost of ownership tradeoffs between an attenuated PSM I-Line process and a DUV binary process are discussed.

  6. Fracture resistance of endodontically treated teeth restored with ceramic inlays and different base materials.

    Science.gov (United States)

    Saridag, Serkan; Sari, Tugrul; Ozyesil, Atilla Gokhan; Ari Aydinbelge, Hale

    2015-01-01

    This study evaluated the fracture resistance of endodontically treated teeth restored with different base materials and mesioocclusal-distal (MOD) ceramic inlays. Fifty mandibular molars were assigned into five groups (n=10 per group). Group1 (control) comprised intact molar teeth without any treatment. Teeth in other groups were subjected to root canal treatment and restored with MOD ceramic inlays on different base materials. In Group 2, base material was zinc phosphate cement; Group 3's was glass ionomer cement; Group 4's was composite resin, and Group 5's was composite resin reinforced with fiber. Finally, a continuous occlusal load was applied until fracture occurred. Mean fracture resistance of Group 1 (3,027 N) was significantly higher than the other groups (890, 1,070, 1,670, 1,226 N respectively). Fracture resistance of Group 4 was statistically comparable with Group 5 and significantly higher than Groups 2 and 3 (pinlay restorations could affect the fracture resistance of endodontically treated teeth.

  7. Short-term clinical evaluation of inlay and onlay restorations made with a ceromer.

    Science.gov (United States)

    Monaco, C; Baldissara, P; dall'Orologio, G D; Scotti, R

    2001-01-01

    This prospective clinical trial evaluated the clinical acceptability of a new material, ceromer, used for inlay and onlay restorations in single- or multisurface cavities of posterior teeth. Forty-three Targis inlay and onlay restorations were placed in 25 patients and evaluated using the United States Public Health Service criteria. The laboratory work was conducted by three dental technicians according to the manufacturer's recommendations. Twenty-five restorations were luted with Syntac bonding system and Variolink II, and 18 were luted with Scotchbond Multi Purpose and Opal Luting Composite. The recalls were done at 6, 12, and 18 months. Restorations were evaluated for six parameters and scored as ideal (A), clinically acceptable (B), or clinically unacceptable (C). Indirect restorations received, after 18 months, scores of A at the following rates: color match 77%; marginal discoloration 93%; secondary caries 100%; anatomic form 93%; and marginal integrity 95%. For these parameters, statistical analysis indicated no significant differences at baseline and after 18 months. Postoperative hypersensitivity was reported by seven patients at baseline, but it decreased and there was no hypersensitivity at 12- and 18-month follow-ups. Over an 18-month period the Targis restorative system yielded good clinical service.

  8. Role of Alumina Basicity in CO2Uptake in 3-Aminopropylsilyl-Grafted Alumina Adsorbents.

    Science.gov (United States)

    Potter, Matthew E; Cho, Kyeong Min; Lee, Jason J; Jones, Christopher W

    2017-05-22

    Oxide-supported amine materials are widely known to be effective CO 2 sorbents under simulated flue-gas and direct-air-capture conditions. Most work has focused on amine species loaded onto porous silica supports, though potential stability advantages may be offered through the use of porous alumina supports. Unlike silica materials, which are comparably inert, porous alumina materials can be tuned to have substantial acidity and/or basicity. Owing to their amphoteric nature, alumina supports play a more active role in CO 2 sorption than silica supports, potentially directly participating in the adsorption process. In this work, primary amines associated with 3-aminopropyltriethoxysilane are grafted onto two different mesoporous alumina materials having different levels of basicity. Adsorbent materials with different amine loadings are prepared, and the CO 2 -adsorption behavior of similar amines on the two alumina supports is demonstrated to be different. At low amine loadings, the inherent properties of the support surface play a significant role, whereas at high amine loadings, when the alumina surface is effectively blocked, the sorbents prepared on the two supports behave similarly. At high amine loadings, amine-CO 2 -amine interactions are shown to dominate, leading to adsorbed species that appear similar to the species formed over silica-supported amine materials. The sorbent properties are comprehensively characterized using N 2 physisorption analysis, in situ FTIR spectroscopy, and adsorption microcalorimetry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Fracture resistance of endodontically treated teeth restored with indirect composite inlay and onlay restorations – An in vitro study

    Science.gov (United States)

    Alshiddi, Ibraheem F.; Aljinbaz, Amjad

    2015-01-01

    Objective The purpose of this in vitro study was to evaluate and compare the fracture resistance and fracture mode of extensive indirect inlay and onlay composite resin restorations performed for endodontically treated premolars. Materials and methods A total of 55 extracted maxillary premolars were randomly divided into four groups. The first group (n = 15) remained untreated to serve as a positive control; the second group (n = 15) was endodontically treated with inlay cavities prepared and restored with indirect composite inlay restorations; the third group (n = 15) was also endodontically treated with onlay cavities prepared and restored with indirect composite onlay restorations; and the fourth group (n = 10) was endodontically treated with mesio-occlusodistal (MOD) cavities prepared and left unrestored to serve as negative controls. Dual cure indirect composite resin was used to fabricate the inlay and onlay restorations performed for the second and third groups, respectively. All teeth were subjected to compressive axial loading test using a metal ball (6 mm in diameter) in a universal testing machine (Instron 1195) with a cross-head speed of 0.5 mm/min until a fracture occurred. Statistical analysis of fracture resistance and fracture mode were performed with analysis of variance (ANOVA) (α = 0.05) and Kruskal–Wallis (α = 0.05) tests, respectively. Results For the four treatment groups, the mean fracture resistance values were 1326.9 N, 1500.1 N, 1006.1 N, and 702.7 N, respectively. Statistical analyses showed no significant differences between the mean fracture resistance of the intact tooth group and the inlay restoration group (p > 0.05), while significant differences were observed between the mean fracture resistance of all the other groups (p inlay and onlay restorations. However, the fractures that accompanied the inlay restorations were more severe and were unable to be restored. PMID:26792970

  10. Synthesis of alumina-α using aluminium acetate; Sintese de alumina-α utilizando acetato de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Cartaxo, J.M.; Galdino, M.N.; Neves, G.A., E-mail: lulianamelo25@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Menezes, R.R.; Ferreira, H.S. [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Departamento de Engenharia de Materiais

    2011-07-01

    In the face of great technological importance of alumina, this paper aims to synthesize the α-alumina using chemical activation from aluminum acetate. The synthesized powders were characterized by X-ray diffraction and thermal analysis. The results obtained proved the thermal decomposition of the precursor, as well as possible metastable phases of alumina before the phase transformation in α. There was also difficult to obtain α-alumina from aluminum acetate, on the other hand there was, comparatively, that the chemical activation accelerated the synthesis of α-alumina. (author)

  11. Chairside vs. labside ceramic inlays: effect of temporary restoration and adhesive luting on enamel cracks and marginal integrity.

    Science.gov (United States)

    Frankenberger, Roland; Krämer, Norbert; Appelt, Andreas; Lohbauer, Ulrich; Naumann, Michael; Roggendorf, Matthias J

    2011-09-01

    To assess the influence of different temporary restorations and luting techniques of labside and chairside ceramic inlays on enamel defects and marginal integrity. 120 extracted human third molars received MOD preparations with one proximal box each limited in either enamel or dentin. 64 Cerec 2 inlays and 56 IPS Empress I inlays were randomly assigned to the following groups (fabrication mode: chairside (CS)=no temporary restoration (TR), labside (LS)=TR with Luxatemp (L) inserted with TempBond NE, or Systemp.inlay (SI) without temporary cement), luting technique: SV=Syntac/Variolink II, RX=RelyX Unicem: A: Cerec inlays were luted with (1) CS/SV. (2) CS/SV/Heliobond separately light-cured. (3) CS/RX. (4) LS/L/SV. (5) LS/L/RX. (6) LS/SI/SV. (7) LS/SI/RX. (8) LS/SI/RX with selective enamel etching. B: Empress. (9) L/SV. (10) L/SV/Heliobond separately light-cured. (11) L/RX. (12) SI/SV. (13) SI/SV, Heliobond separately lightcured. (14) SI/RX. (15) SI/RX after selective enamel etching. Before and after thermomechanical loading (TML: loading time of TR 1000×50N+25 thermocycles (TC) between +5°C and +55°C; clinical simulation: 100,000×50N+2500 TC) luting gaps, enamel cracks, and marginal adaptation to enamel and dentin were determined under an SEM microscope (200×) using replicas. Loading time of temporary restorations negatively affected enamel integrity and enamel chipping (pinlay (p0.05). Temporary cement negatively affected dentin margins when RelyX Unicem was used (pinlays reduce the risk of enamel cracks and marginal enamel chipping due to omitted temporary restorations. Syntac/Variolink revealed a significantly better performance than RelyX Unicem. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Graphene coated with alumina and its utilization as a thermal conductivity enhancer for alumina sphere/thermoplastic polyurethane composite

    International Nuclear Information System (INIS)

    Kim, Ki Tae; Dao, Trung Dung; Jeong, Han Mo; Anjanapura, Raghu V.; Aminabhavi, Tejraj M.

    2015-01-01

    Graphene was oxidized with H 2 O 2 to introduce additional anchoring sites for effective alumina coating on graphene by the sol–gel method. The X-ray photoelectron spectroscopy studies showed that the oxygen-containing groups such as hydroxyl group useful for coating were introduced by the oxidation. The transmission electron microscopy images and thermogravimetric analysis data demonstrated that the additional anchoring sites enhanced the efficiency of the alumina coating. A small amount of alumina-coated graphene synergistically improved the thermal conductivity of the alumina sphere/thermoplastic polyurethane (TPU) composite without any increase in the electrical conductivity, because the electrical conductivity of graphene effectively decreased by the alumina coating. Moreover, the synergistic effect of a small amount of graphene was enhanced by the alumina coating, and the stiffening of the alumina sphere/TPU composite due to the added graphene was alleviated by the alumina coating. - Highlights: • Oxidation of graphene with H 2 O 2 introduced anchoring sites for alumina coating. • The anchoring sites improved the efficiency of alumina coating on graphene. • The alumina-coated graphene synergistically enhanced the thermal conductivity

  13. Evaluation of the accuracy and precision of four intraoral scanners with 70% reduced inlay and four-unit bridge models of international standard.

    Science.gov (United States)

    Uhm, Soo-Hyuk; Kim, Jae-Hong; Jiang, Heng Bo; Woo, Chang-Woo; Chang, Minho; Kim, Kyoung-Nam; Bae, Ji-Myung; Oh, Seunghan

    2017-01-31

    The aims of this study were to evaluate the feasibility of 70% reduced inlay and 4-unit bridge models of International Standard (ISO 12836) assessing the accuracy of laboratory scanners to measure the accuracy of intraoral scanner. Four intraoral scanners (CS3500, Trios, Omnicam, and Bluecam) and one laboratory scanner (Ceramill MAP400) were used in this study. The height, depth, length, and angle of the models were measured from thirty scanned stereolithography (STL) images. There were no statistically significant mean deviations in distance accuracy and precision values of scanned images, except the angulation values of the inlay and 4-unit bridge models. The relative errors of inlay model and 4-unit bridge models quantifying the accuracy and precision of obtained mean deviations were less than 0.023 and 0.021, respectively. Thus, inlay and 4-unit bridge models suggested by this study is expected to be feasible tools for testing intraoral scanners.

  14. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  15. Fracture resistance of prepared premolars restored with bonded new lab composite and all-ceramic inlay/onlay restorations: Laboratory study.

    Science.gov (United States)

    Wafaie, Ramy Ahmed; Ibrahim Ali, Ashraf; Mahmoud, Salah Hasab

    2018-01-25

    To assess the influence of new light curing lab composite, lithium-disilicate glass-ceramic and yttrium-stabilized zirconia-based ceramic on the fracture resistance of maxillary premolars with class II inlay and onlay preparations. Seventy sound maxillary premolars were divided randomly into seven main groups. The first group was left intact (control group). The remaining six groups were prepared with inlay and onlay cavities and restored with lab composite (SR Nexco), lithium-disilicate glass-ceramic (IPS e.max Press) and yttrium-stabilized zirconia-based ceramic (ICE Zirkon). The restorations were cemented with luting resin composite (Variolink N). All specimens were thermocycled 5000 cycles between 5°C ± 2°C and 55°C ± 2°C and were then cyclic loaded for 500 000 cycles. The specimens were subjected to a compressive load in a universal testing machine using a metal sphere until fracture occurred. The results were analyzed by 2-way ANOVA and Tukey HSD post hoc tests. The level of significance was set at P inlays and onlays (P > .05). However, statistically significant differences were found among the means of control group and the groups restored with lab composite inlays, lab composite onlays, pressable glass ceramic inlays and pressable glass ceramic onlays (P inlay and onlay restorations is inferior to the intact teeth when lab composite is used. Conversely, when a ceramic material being used, the prepared teeth for inlay and onlay restorations showed a comparable strength to the intact teeth especially zirconia ceramic. Premolar teeth restored with zirconia ceramic inlays and onlays exhibited fracture resistance comparable to intact teeth. © 2018 Wiley Periodicals, Inc.

  16. Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification

    Energy Technology Data Exchange (ETDEWEB)

    Lamouri, S.; Hamidouche, M.; Bouaouadja, N.; Belhouchet, H.; Garnier, V.; Fantozzi, G.; Trelkat, J.F.

    2017-07-01

    In this work, we studied the aptitude to sintering green bodies using γ-Al2O3 transition alumina as raw powder. We focused on the influence of the heating rate on densification and microstructural evolution. Phase transformations from transition alumina γ→δ→θ→α-Al2O3 were studied by in situ X-rays diffraction from the ambient to 1200°C. XRD patterns revealed coexistence of various phase transformations during the heating cycle. DTA and dilatometry results showed that low heating rate leads to a significant reduction of the temperature of the α-Al2O3 alumina formation. Around 1190, 1217 and 1240°C were found when using 5, 10 and 20°C/min of heating rate, respectively. The activation energy for θ-Al2O3→α-Al2O3 transformation calculated by Kissinger and JMA equations using dilatometry method were 464.29 and 488.79kJ/mol, respectively and by DTA method were 450.72 and 475.49kJ/mol, respectively. In addition, the sintering of the green bodies with low heating rate promotes the rearrangement of the grains during θ-Al2O3→α-Al2O3 transformation, enhancing the relative density to 95% and preventing the development of a vermicular structure. (Author)

  17. Influence of alumina characteristics on glaze properties

    Directory of Open Access Journals (Sweden)

    Arrufat, S.

    2010-10-01

    Full Text Available Aluminium oxide is a synthetic raw material manufactured from bauxite by the Bayer process, whose Al2O3 content typically exceeds 99%. Four main types of alumina can be defined, depending on the processing used: hydrargillite Al(OH3, boehmite AlOOH, transition aluminas (calcined at low temperatures, 1000 °C, with an intermediary crystallographic structure between hydrates and alpha alumina, and α-Al2O3 (calcined at high temperatures, >1100 °C. In glaze manufacturing, α-Al2O3 is the main type of alumina used. This raw material acts as a matting agent: the matt effect depends on alumina particle size and content in the glaze. This study examines the effect of the degree of alumina calcination on glaze technical and aesthetic properties. For this purpose, aluminas with different degrees of calcination were added to a glaze formulated with a transparent frit and kaolin, in order to simplify the system to be studied. The results show that, depending on the degree of calcination, alumina particles can react with the glaze components (SiO2, CaO, and ZnO to form new crystalline phases (anorthite and gahnite. Both crystallisations extract CaO and ZnO from the glassy phase, increasing glassy phase viscosity. The variation in crystalline phases and glassy phase viscosity yields glazes with different technical and aesthetic properties.

    El óxido de aluminio es una materia prima sintética fabricada a partir de la bauxita por medio del proceso Bayer, cuyo contenido de Al2O3 supera, por regla general, el 99%. Se pueden definir cuatro tipos de alúmina, en función del tipo de proceso usado: hidrargilita Al(OH3, boehmita AlOOH, alúminas de transición (calcinadas a bajas temperaturas, 1000 °C, con una estructura cristalográfica intermedia entre los hidratos y la alfa alúmina, y la α-Al2O3 (calcinada a

  18. Microstructural evolution of alumina-zirconia nanocomposites

    International Nuclear Information System (INIS)

    Ojaimi, C.L.; Chinelatto, A.S.A.; Chinelatto, A.L.; Pallone, E.M.J.A.

    2012-01-01

    Ceramic materials have limited use due to their brittleness. The inclusion of nanosized particles in a ceramic matrix, which are called nanocomposites, and ceramic processing control by controlling the grain size and densification can aid in obtaining ceramic products of greater strength and toughness. Studies showed that the zirconia nano inclusions in the matrix of alumina favors an increase in mechanical properties by inhibiting the grain growth of the matrix and not by the mechanism of the transformation toughening phase of zirconia. In this work, the microstructural evolution of alumina nanocomposites containing 15% by volume of nanometric zirconia was studied. From the results it was possible to understand the sintering process of these nanocomposites. (author)

  19. Silica containing highly porous alumina ceramic

    Science.gov (United States)

    Svinka, R.; Svinka, V.; Zake, I.

    2011-04-01

    Porous alumina ceramic were produced by slip casting of aqueous alumina slurry with added small amount of metallic aluminium powder. Pores form in result of chemical reaction of aluminum with water by hydrogen gas evolution reaction and solidification of suspension. Porosity of such materials sintered at a temperature of 1600 - 1750°C varies from 60 to 90%. Pore size distribution and mechanical strength of these materials depend largely on the grain size of used raw materials. The major part of pores in the materials produced without additive of silica are larger than 10 ±m, but with 5 - 10 wt.% additive of silica in the raw mix pore size decreases considerably. The sintering shrinkage decreases to 2.5%. Coefficient of thermal expansion equally decreases from 8.9-10-6 K-1 to 7.1 10-6 K-1 and classification temperature increases to 1600°C, while deformation at high temperature decreases considerably.

  20. Kaolin as a Source of Silica and Alumina For Synthesis of Zeolite Y and Amorphous Silica Alumina

    Directory of Open Access Journals (Sweden)

    Sri Rahayu Endang

    2018-01-01

    Full Text Available Kaolin is the clay mineral which containing silica (SiO2 and alumina (Al2O3 in a high percentage, that can be used as a nutrient in the synthesis of zeolites and amorphous silica alumina (ASA. The objective of this research is to convert the Belitung kaolin into silica and alumina as nutrients for the synthesis of zeolites and amorphous silica alumina, which are required in the preparation of the catalysts. Silica and alumina contained in the kaolin were separated by leaching the active kaolin called as metakaolin, using HCL solution, giving a solid phase rich silica and a liquid phase rich alumina. The solid phase rich silica was synthesized to zeolite Y by adding seed of the Y Lynde type, through the hydrothermal process with an alkaline condition. While, the liquid phase rich alumina was converted into an amorphous silica alumina through a co precipitation method. Characterization of zeolite and ASA were done using XRD, surface area and pore analyzer and SEM. The higher of alumina in liquid phase as a result of the rising molar of HCL in the leaching process was observed, but it didn’t work for its rising time. Products of ASA and zeolite Y were obtained by using liquid phase rich alumina and solid phase rich silica, respectively, which resulted through leaching metakaolin in 2.5 M HCl at temperature of 100° C for 2 hours.

  1. In-beam dielectric properties of alumina

    International Nuclear Information System (INIS)

    Molla, J.; Ibarra, A.; Hodgson, E.R.

    1995-01-01

    The dielectric properties (permittivity and loss tangent) of a 99.7% purity alumina grade have been measured over a wide frequency range (1 kHz-15 GHz) before and after 2 MeV electron irradiation at different temperatures. The dielectric properties at 15 GHz were measured during irradiation. Both prompt and fluence effects are observed together with permanent changes which continue to evolve following irradiation. The behaviour is complex, consistent with both radiation induced electronic effects and aggregation processes. ((orig.))

  2. Performance characteristics of porous alumina ceramic structures

    International Nuclear Information System (INIS)

    Latella, B.A.; Liu, T.

    2000-01-01

    Porous ceramics have found a wide range of applications as filters for liquids and gases. The suitability of materials for use in these types of applications depends on the microstructure (grain size, pore size and pore volume fraction) and hence the mechanical and thermal properties. In this study alumina ceramics with different levels of porosity and controlled pore sizes were fabricated and the surface damage and fracture properties were examined. Copyright (2000) The Australian Ceramic Society

  3. Nitrogen Adsorption Study of Organised Mesoporous Alumina

    Czech Academy of Sciences Publication Activity Database

    Čejka, Jiří; Žilková, Naděžda; Rathouský, Jiří; Zukal, Arnošt

    2001-01-01

    Roč. 3, č. 22 (2001), s. 5076-5081 ISSN 1463-9076 R&D Projects: GA AV ČR IAA4040001; GA MŠk ME 404 Grant - others:NATO(XE) SfP 974217 Institutional research plan: CEZ:AV0Z4040901 Keywords : nitrogen adsorption study * organised mesoporous alumina * reference nonporous solid Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.787, year: 2001

  4. Preparation and Characterization of Activated Alumina

    Science.gov (United States)

    Rabia, A. R.; Ibrahim, A. H.; Zulkepli, N. N.

    2018-03-01

    Activated alumina is a high surface area and highly porous form of aluminum oxide that can be employed for contaminant species adsorb from ether gases or liquids without changing its form. The research in getting this material has generated huge interested. Thus, this paper presented preparation of activated alumina from chemical process. Pure aluminum (99.9% pure) reacted at room temperature with an aqueous NaOH in a reactor to produce a solution of sodium aluminate (NaAlO2). This solution was passed through filter paper and the clear filtrate was neutralized with H2SO4, to pH 6, 7 or 8, resulting in the precipitation of a white gel, Al(OH)3·XH2O. The washed gel for sulfate ions were dried at 80 °C for 6 h, a 60 mesh sieve was to separate and sort them into different sizes. The samples were then calcined (burn) for 3h in a muffle furnace, in air, at a heating rate of 2 °C min-1. The prepared activated alumina was further characterized for better understanding of its physical properties in order to predict its chemical mechanism.

  5. Considerations in computer-aided design for inlay cranioplasty: technical note.

    Science.gov (United States)

    Nout, Erik; Mommaerts, Maurice Y

    2018-03-01

    Cranioplasty is a frequently performed procedure that uses a variety of reconstruction materials and techniques. In this technical note, we present refinements of computer-aided design-computer-aided manufacturing inlay cranioplasty. In an attempt to decrease complications related to polyether-ether-ketone (PEEK) cranioplasty, we gradually made changes to implant design and cranioplasty techniques. These changes include under-contouring of the implant and the use of segmented plates for large defects, microplate fixation for small temporal defects, temporal shell implants to reconstruct the temporalis muscle, and perforations to facilitate the drainage of blood and cerebrospinal fluid and serve as fixation points. From June 2016 to June 2017, 18 patients underwent cranioplasty, and a total of 31 PEEK and titanium implants were inserted. All implants were successful. These changes to implant design and cranioplasty techniques facilitate the insertion and fixation of patient-specific cranial implants and improve esthetic outcomes.

  6. Multi-channel peristaltic pump for microfluidic applications featuring monolithic PDMS inlay.

    Science.gov (United States)

    Skafte-Pedersen, Peder; Sabourin, David; Dufva, Martin; Snakenborg, Detlef

    2009-10-21

    The design, fabrication and characterization of a miniaturized, mechanically-actuated 12-channel peristaltic pump for microfluidic applications and built from simple, low-cost materials and fabrication methods is presented. Two pump configurations are tested, including one which reduces pulsating flow. Both use a monolithic PDMS pumping inlay featuring three-dimensional geometries favourable to pumping applications and 12 wholly integrated circular channels. Flow rates in the sub-microL min(-1) to microL min(-1) range were obtained. Channel-to-channel flow rate variability was comparable to a commercial pumping system at lower flow rates. The small footprint, 40 mm by 80 mm, of the micropump renders it portable, and allows its use on microscope stages adjacent to microfluidic devices, thus reducing system dead volumes. The micropump's design allows potential use in remote and resource-limited locations.

  7. Electron microscopy study of an Old Russian (XII century) encolpion cross with black inlay

    Science.gov (United States)

    Kolobylina, N. N.; Greshnikov, E. A.; Vasiliev, A. L.; Tereschenko, E. Yu.; Zaytseva, I. E.; Makarov, N. A.; Kashkarov, P. K.; Yatsishina, E. B.; Kovalchuk, M. V.

    2017-07-01

    The phase compositions of the basic material (alloy) of a pre-Mongolian Old Russian encolpion cross found near Suzdal and its black inlay have been investigated by methods of scanning and transmission electron microscopy and energy-dispersive X-ray microanalysis. The cross material is lead-zinc-tin α-bronze, and the black is copper sulfide with lead inclusions. As a result of the corrosion, tin and copper oxides and zinc sulfides, which made the cross dark gray, were formed on its surface. It is shown that the corrosion depth is as large as 50 μm; thus, laps must be prepared to accurately determine the morphology and phase composition of the corrosion layer. Decoration with black was apparently performed by pouring with copper sulfide melt or melting a powder preliminarily placed in grooves forming an image on the surface.

  8. Dowel-inlay a new treatment approach to traumatic root fracture

    Directory of Open Access Journals (Sweden)

    R G Sunil Reddy

    2010-01-01

    Full Text Available Tooth trauma has been and continues to be a common occurrence that every dental professional must be prepared to assess and treat when necessary. Tooth trauma and its management loom as a major challenge to the dental practitioner. Transverse root fractures occur most commonly in the maxillary teeth. This case report describes a new technique for the management of transverse root fractures in zone 2 with dowel inlay. This enables the utilization of the fractured fragment crown for stabilizing a transverse root fracture in zone 2, in a simple, economical, and minimally invasive manner. It can save considerable time over other alternative treatment options available for the treatment of trauma zone 2 fractures. Both clinical and radiographic follow-up have shown a stable condition, without any probing defects, ongoing root resorption or periapical pathosis.

  9. Utilization of iTero digital impression unit for resin composite inlay.

    Science.gov (United States)

    Laman, Stephen A; Frey, Gary N; Patel, Shalizeh A; Quock, Ryan L

    2014-01-01

    Historically, traditional elastomeric impression techniques for indirect fixed procedures have presented challenges for the operator, laboratory, and patient. Recent digital impression unit technology offers a compelling alternative to elastomeric impressions. The iTero system applies parallel confocal imaging to create a virtual impression that can be easily captured, edited, and uploaded electronically to the dental laboratory. Computer-aided design/computer-aided manufacturing technology is applied to the virtual impression to create an unlimited number of identical polyurethane models. This case report is presented from the perspectives of the clinicians and the laboratory technician using an iTero system to treat a left mandibular second premolar with a resin composite inlay.

  10. Inlay-Retained Fixed Dental Prosthesis: A Clinical Option Using Monolithic Zirconia

    Directory of Open Access Journals (Sweden)

    Davide Augusti

    2014-01-01

    Full Text Available Different indirect restorations to replace a single missing tooth in the posterior region are available in dentistry: traditional full-coverage fixed dental prostheses (FDPs, implant-supported crowns (ISC, and inlay-retained FDPs (IRFDP. Resin bonded FDPs represent a minimally invasive procedure; preexisting fillings can minimize tooth structure removal and give retention to the IRFDP, transforming it into an ultraconservative option. New high strength zirconia ceramics, with their stiffness and high mechanical properties, could be considered a right choice for an IRFDP rehabilitation. The case report presented describes an IRFDP treatment using a CAD/CAM monolithic zirconia IRFDP; clinical and laboratory steps are illustrated, according to the most recent scientific protocols. Adhesive procedures are focused on the Y-TZP and tooth substrate conditioning methods. Nice esthetic and functional integration of indirect restoration at two-year follow-up confirmed the success of this conservative approach.

  11. Size dependent phase and morphological transformation of alumina nanoparticles

    Science.gov (United States)

    Dommisa, D. B.; Dash, R. K.

    2018-03-01

    The size effect of the alumina nanoparticles on the phase and morphological transition by thermal treatment at various temperatures is investigated by choosing two different sizes alumina nanoparticles. Our experimental results revealed that phase and morphological transformation behavior is significantly different for smaller size alumina nanoparticles than that of larger size. The more stable alpha phase transformation occurs at a higher temperature for smaller size alumina nanoparticles in comparison to that of the larger size alumina nanoparticles. Moreover, the experimental facts also elucidated that the nucleation and growth process at the nanoscale for the phase transition is also size dependent. Our experimental result from the FESEM and TEM analysis also revealed that there is a direct correlation between phase and morphological transition of alumina nanoparticles size which is consistent with the XRD results. Therefore, we believe that our experimental findings can be extended to other complex nanomaterials for understanding the size-dependent phase and morphological transformation at the nanoscale.

  12. Influence of restorative material and proximal cavity design on the fracture resistance of MOD inlay restoration.

    Science.gov (United States)

    Liu, Xiaozhou; Fok, Alex; Li, Haiyan

    2014-03-01

    This study aimed to evaluate the effects of the restorative material and cavity design on the facture resistance of inlay restorations under a compressive load using acoustic emission (AE) measurement. Two restorative materials, a composite resin (MZ100, 3M ESPE) and a ceramic (IPS Empress CAD, Ivoclar Vivadent), and two cavity designs, non-proximal box and proximal box, were studied. Thirty-two extracted human third molars were selected and divided into 4 groups. The restorative materials and cavity designs used for the four groups were: (1) composite and non-proximal box; (2) ceramic and non-proximal box; (3) composite and proximal box; (4) ceramic and proximal box. The restored molars were loaded in a MTS machine via a loading head of diameter 10mm. The rate of loading was 0.1mm/min. During loading, an AE system was used to monitor the debonding and fracture of the specimens. The load corresponding to the first AE event, the final maximum load sustained, as well as the total number of AE events recorded were used to evaluate the fracture resistance of the restored teeth. For the initial fracture load, Group 2 (236.15N)Group 2 (1685)>Group 3 (239)>Group 1 (221). The differences from pairwise comparisons in the initial fracture load and final load were mostly insignificant statistically (p>0.05), the only exception being that between Groups 2 and 3 in the initial fracture load (p=0.039). For the total number of AE events, statistically significant differences (pinlays, the use of composite resin as the restorative material may provide higher fracture resistance than using ceramic. Using a proximal box design for the cavity may further improve the fracture resistance of the inlay restoration, although the improvement was not statistically significant under axial compression. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Effect of proximal box elevation with resin composite on marginal quality of ceramic inlays in vitro.

    Science.gov (United States)

    Frankenberger, Roland; Hehn, Julia; Hajtó, Jan; Krämer, Norbert; Naumann, Michael; Koch, Andreas; Roggendorf, Matthias J

    2013-01-01

    The objective of this study was to evaluate the marginal quality and resin-resin transition of milled CAD/CAM glass-ceramic inlays in deep proximal cavities with and without 3-mm proximal box elevation (PBE) using resin composites before and after thermomechanical loading. MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 48 extracted human third molars. Proximal boxes ending in dentin were elevated for 3 mm with different resin composites (RelyX Unicem, G-Cem, and Maxcem Elite as self-adhesive resin cements and Clearfil Majesty Posterior as restorative resin composite in one or three layers bonded with AdheSE) or left untreated. IPS Empress CAD inlays were luted with Syntac and Variolink II (n = 8). Marginal quality as well as the PBE-ceramic interface were analyzed under an SEM using epoxy resin replicas before and after thermomechanical loading (100,000 × 50 N and 2,500 thermocycles between +5°C and +55°C). Bonding glass-ceramic directly to dentin showed the highest amounts of gap-free margins in dentin (92%, p resin composite applied in three layers achieved 84% gap-free margins in dentin; PBE with self-adhesive resin cements exhibited significantly more gaps in dentin (p resin composite, PBE may be an alternative to ceramic bonding to dentin. Self-adhesive resin cements seem not suitable for this indication. For deep proximal boxes ending in dentin, a PBE may be an alternative to conventional techniques.

  14. Method for preparing Pb-.beta."-alumina ceramic

    Science.gov (United States)

    Hellstrom, Eric E.

    1986-01-01

    A process is disclosed for preparing impermeable, polycrystalline samples of Pb-.beta."-alumina ceramic from Na-.beta."-alumina ceramic by ion exchange. The process comprises two steps. The first step is a high-temperature vapor phase exchange of Na by K, followed by substitution of Pb for K by immersing the sample in a molten Pb salt bath. The result is a polycrystalline Pb-.beta."-alumina ceramic that is substantially crack-free.

  15. Tribological and stability investigations of alkylphosphonic acids on alumina surface

    International Nuclear Information System (INIS)

    Cichomski, M.; Kośla, K.; Grobelny, J.; Kozłowski, W.; Szmaja, W.

    2013-01-01

    Alumina substrates are commonly used for various micro-/nanoelectromechanical systems (MEMS/NEMS). For efficient and lifetime longevity of these devices, lubricant films of self-assembled monolayers (SAMs) with nanometer thickness are increasingly being employed. In the present paper, we report preparation, tribological and stability investigations of alkylphosphonic acids on the alumina surface. The alkylphosphonic acids were prepared on the alumina surface using the liquid phase deposition method. The effectiveness of modification of the alumina surface by alkylphosphonic acids was investigated using water contact angle measurements, secondary ion mass spectrometry, X-ray photoelectron and infrared spectroscopy. Frictional behavior in milinewton load range was studied by microtribometry. It is shown that surface modification of the alumina surface by alkylphosphonic acids reduces the coefficient of friction values compared to the unmodified alumina. In comparison to the non-modified alumina surface, all tested alkylphosphonic acids cause a decrease in the friction coefficients in friction tests for counterparts made from different materials, such as steel, zirconia and silicon nitride. It is also found that the alumina surface modified by alkylphosphonic acids with longer chain has a higher degree of hydrophobicity and lower coefficient of friction. The best frictional properties are obtained for the system consisting of the alumina surface modified by n-octadecylphosphonic acid and silicon nitride counterpart. Stability tests in different environmental conditions: laboratory, acidic and alkaline solutions were also monitored.

  16. Numerical study of self-adaptive vibration suppression for flexible structure using interior inlay viscous fluid unit method

    Science.gov (United States)

    Zhang, Xiongwen; Li, Jun; Xu, Hui; Li, Guojun

    2006-11-01

    This paper investigates the usage of an interior inlay viscous fluid unit as a new vibration suppression method for flexible structures via numerical simulations. The first and second modes of vibration for a beam have been calculated using the commercial computational fluid dynamic package Fluent6.1, together with the liquid surface distribution and the fluid force. The calculated results show that the inlay fluid unit has suppressive effects on flexible structures. The liquid converges self-adaptively to locations of larger vibrations. The fluid force varies with the beam vibration at a phase difference of more than 180°. Thus the fluid force suppresses the beam vibration at most of the time.

  17. Small-aperture corneal inlay in presbyopic patients with prior phakic intraocular lens implantation surgery: 3-month results

    Directory of Open Access Journals (Sweden)

    Huseynova T

    2013-08-01

    Full Text Available Tukezban Huseynova,1 Tomomi Kanamori,1 George O Waring IV,2 Minoru Tomita1,3,4 1Shinagawa LASIK Center, Tokyo, Japan; 2Medical University of South Carolina, Charleston, SC, USA; 3Wenzhou Medical College, Wenzhou, People’s Republic of China; 4Eye Can Cataract Surgery Center, Metro Manila, Philippines Abstract: We report a series of three case reports of KAMRA inlay implantation procedures in presbyopic patients with a history of prior phakic intraocular lens implantation surgery. Three-month results showed a two to five-line improvement for uncorrected near visual acuity. The absolute uncorrected near visual acuity change for case 1 was from J4 to J2, for case 2 was from J6 to J4, and for case 3 was from J10 to J5. No significant change of uncorrected distance visual acuity was observed in all three cases. Keywords: phakic intraocular lens, IOL, KAMRA, intracorneal inlay

  18. Cyclic Creep and Recovery Behavior of Nextel(Trademark) 720/Alumina Ceramic Matrix Composite at 1200deg C in Air and in Steam Environments

    Science.gov (United States)

    2007-09-01

    cement . Composites today are everyday items. As technology advances so does the need for composites for advanced materials. Aerospace has taken...Furthermore, microstructural deformational failure mechanisms present in air and in steam environments are explored. 4 II. Background 2.1...is processed at high temperatures [6, 2]. Common types of ceramic matrix materials being studied are alumina, silicon nitride and silicon carbide

  19. Formation of alumina-aluminide coatings on ferritic-martensitic T91 steel

    Directory of Open Access Journals (Sweden)

    Choudhary R.K.

    2014-01-01

    Full Text Available In this work, alumina-aluminide coatings were formed on ferritic-martensitic T91 steel substrate. First, coatings of aluminum were deposited electrochemically on T91 steel in a room temperature AlCl3-1-ethyl-3-methyl imidazolium chloride ionic liquid, then the obtained coating was subjected to a two stage heat treatment procedure consisting of prolonged heat treatment of the sample in vacuum at 300 ○C followed by oxidative heat treatment in air at 650 ○C for 16 hours. X-ray diffraction measurement of the oxidatively heat treated samples indicated formation of Fe-Al and Cr-Al intermetallics and presence of amorphous alumina. Energy dispersive X-ray spectroscopy measurement confirmed 50 wt- % O in the oxidized coating. Microscratch adhesion test conducted on alumina-aluminide coating formed on T91 steel substrate showed no major adhesive detachment up to 20 N loads. However, adhesive failure was observed at a few discrete points on the coating along the scratch track.

  20. In vitro evaluation of fracture resistance of Fiber-Reinforced Composite inlay bridges in upper anterior and lower posterior teeth

    Directory of Open Access Journals (Sweden)

    Jalalian E.

    2007-07-01

    Full Text Available Background and Aim: Considering flexural strength of fiber-reinforced composites (FRC and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar. Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195 with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and  1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on composite facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T  test a significant statistical difference was observed between two groups (P<0.001. The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

  1. Human skulls with turquoise inlays: pre hispanic origin or replicas?; Craneos humanos con teselas de turquesa: origen prehispanico o replicas?

    Energy Technology Data Exchange (ETDEWEB)

    Silva V, Y. [FIME-UANL, Pedro A. del Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon (Mexico); Castillo M, M.T.; Bautista M, J.P. [DRPMZA/INAH. Direccion de Registro Publico de Monumentos y Zonas Arqueologicas, Victoria 110, Copilco El Bajo, 04340 Mexico D.F. (Mexico); Arenas A, J. [IFUNAM, Circuito de la Investigacion Cientifica s/n, Ciudad Universitaria, 04510 Mexico D.F. (Mexico)]. e-mail: ysilva@fisica.unam.mx

    2006-07-01

    The lack of archaeological context determining if the manufacture of two human skulls adorned with turquoise inlays have pre-Columbian origin or not (replicas), led to perform other studies. Under these conditions, besides orthodox methodology commonly used to assign chronology and cultural aspects as form, style, decoration, iconography, etc., it was necessary to obtain more results based on the use of characterization techniques. The techniques employed were Scanning Electron Microscopy (SEM), X-Ray Energy Dispersive Spectroscopy (EDS), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), in order to determine the manufacture techniques and chemical composition of the materials used for the cementant. SEM analysis showed the presence of zones composed by Ca, O, C and Al. In some cases Mg, Cl, Fe and Pb were identified. High concentration of Cu was present in all samples, due to residues of turquoise inlays (CuAI{sub 6}(PO{sub 4}){sub 4}(OH){sub 8}(H{sub 2}O){sub 4}) with which the skulls were decorated. In the cementant was identified the Ca as base element of the cementant, as well as particles < 100 nm with irregular morphology and other amorphous zones. FTIR spectrums indicated the presence of organic substances that could be used as agglutinating in the cementant. The current work shows a progress identifying involved techniques in the manufacturing of two human skulls with turquoise inlays. (Author)

  2. Mechanical properties of alumina-PEEK unidirectional composite - Compression, shear, and tension

    Science.gov (United States)

    Kriz, R. D.; Mccolskey, J. D.

    1990-01-01

    An Al2O3 (alumina)-fiber composite with high strain to failure was fabricated with a thermal plastic PEEK (poly-ether-ether-ketone). The Al2O3-PEEK composite shows a marked improvement over thermally setting composite in that it absorbs 150 percent more elastic-strain energy at 76 K than at room temperature. This increase in fracture toughness at low temperatures can provide improved fatigue performance for thermal isolation straps at low temperature. Other mechanical property results suggest improvements for applications where graphite-epoxy materials are presently being used at low temperatures and where light weight is not a critical issue.

  3. Low Temperature MOCVD-Processed Alumina Coatings

    OpenAIRE

    Gleizes, Alain; Sovar, Maria-Magdalena; Samélor, Diane; Vahlas, Constantin

    2006-01-01

    We first present a Review about the preparation of alumina as thin films by the technique of MOCVD at low temperature (550°C and below). Then we present our results about thin films prepared by the low pressure MOCVD technique, using aluminium tri-isopropoxide as a source, and characterized by elemental analysis (EMPA, EDS, ERDA, RBS), FTIR, XRD and TGA. The films were grown in a horizontal, hot-wall reactor, with N2 as a carrier gas either pure or added with water vapour. The deposition t...

  4. Characterization of silane coated hollow sphere alumina-reinforced

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  5. Characterization of silane coated hollow sphere alumina-reinforced ...

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  6. Chemical modification/grafting of mesoporous alumina with polydimethylsiloxane (PDMS)

    NARCIS (Netherlands)

    Pinheiro de Melo, A.F.; Nijmeijer, Arian; Sripathi, V.G.P.; Winnubst, Aloysius J.A.

    2015-01-01

    A method for polydimethylsiloxane grafting of alumina powders is described which involves chemical modification of the surface of mesoporous (5 nm) γ-alumina flakes with a linker (3-aminopropyltriethoxysilane: APTES), either by a solution phase (SPD) or a vapour phase (VPD) reaction, followed by

  7. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    Alumina balls worn out ( 14.2 × 10 − 1 mm 3 ) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their bettertribological properties ...

  8. Micrometer size grains of hot isostatically pressed alumina and its ...

    Indian Academy of Sciences (India)

    Administrator

    The. Vickers hardness in 5⋅5 μm grain microstructure is around 20 GPa in comparison to about 18 GPa in micro- structure with smaller grains of 2⋅2 μm size. Keywords. Alumina ... the technology of alumina ceramics (Munro 1997; Raha- man et al 2007) by purer ... reported interface-reaction-controlled kinetics of HIPing.

  9. Processing and characterization of alumina/LAS bioceramics for ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Alumina allows to recreate the functionality and aesthetics of natural teeth. However, its low frac- ture toughness rises concern regarding use in dental restoration. Structural reliability is addressed here by formulating a material containing alumina and a glass–ceramic from LAS system. The presence of LAS in the.

  10. Processing and characterization of alumina/LAS bioceramics for ...

    Indian Academy of Sciences (India)

    Alumina allows to recreate the functionality and aesthetics of natural teeth. However, its low fracture toughness rises concern regarding use in dental restoration. Structural reliability is addressed here by formulating a material containing alumina and a glass–ceramic from LAS system. The presence of LAS in the mixtures ...

  11. APPLICATION OF VARIOUS TYPES OF ALUMINA AND NANO-γ ...

    African Journals Online (AJOL)

    Preferred Customer

    reported for the synthesis of α-aminonitriles, nucleophilic addition of cyanide ion to imines. (Strecker reaction), is of .... Application of various types of alumina and nano-γ-alumina sulfuric acid. Bull. Chem. Soc. ..... After purification by chromatography on silica gel (ethyl acetate/n-hexane 20:80) α-aminonitriles were obtained.

  12. Investigations on thermoluminescent dosimetry (TLD) with doped alumina ceramics

    International Nuclear Information System (INIS)

    Janas, R.; Huebner, K.

    1976-01-01

    Alumina ceramics doped and burned under various conditions have been investigated with regard to their suitability for thermoluminescent dosimetry. The production of ceramics is described. The properties essential for dosimetric purposes, such as glow curve, energy dose characteristics, fading, recoverability, lower detection limit and energy dependence, are indicated. The advantages and disadvantages of alumina ceramics are compared. (author)

  13. Thermal Conductivity of Alumina-reinforced Zirconia Composites

    Science.gov (United States)

    Bansal, Narottam P.

    2005-01-01

    10-mol% yttria-stabilized zirconia (10SZ) - alumina composites containing 0-30 mol% alumina were fabricated by hot pressing at 1500 C in vacuum. Thermal conductivity was determined at various temperatures using a steady-state laser heat flux technique. Thermal conductivity of the composites increased with increase in alumina content. Composites containing 0, 5, and 10-mol% alumina did not show any change in thermal conductivity with temperature. However, those containing 20 and 30-mol% alumina showed a decrease in thermal conductivity with increase in temperature. The measured values of thermal conductivity were in good agreement with those calculated from the Maxwell-Eucken model where one phase is uniformly dispersed within a second major continuous phase.

  14. Characterization and sintering of niobium-ATR alumina

    International Nuclear Information System (INIS)

    Sibuya, N.H.; Iwasaki, H.; Suzuki, C.K.; Pinatti, D.G.

    1987-01-01

    In the niobium aluminothermy a slag is produced, composed mostly of alumina and other compounds such as niobium oxide and silica. The phase composition of this ATR alumina was characterized by X-ray powder diffractometry, and afterwards this alumina was subjected to leaching processes. It was noticed that the original content of 70% α-alumina in slag rose to 95% after the calcination. ATR alumina (leached and calcined, and without any treatment) was used to make pressed bodies which were fired in air at 1200 to 1400 0 C for 1 to 10,5 hours; and in vacuum at 1550 to 1800$0C for 2 hours. Characterization was done by density measurements, X-ray diffractometry and ultrasonic analysis. Ultrasonic analysis of some vacuum fired bodies showed londitudinal velocities close to the value found in literature. Correlation of several techniques measurements disclosed the niobium oxide interference in sintering. (Author) [pt

  15. Temperature-dependent thermal properties of spark plasma sintered alumina

    Directory of Open Access Journals (Sweden)

    Saheb Nouari

    2017-01-01

    Full Text Available In this work, we report temperature-dependent thermal properties of alumina powder and bulk alumina consolidated by spark plasma sintering method. The properties were measured between room temperature and 250ºC using a thermal constants analyzer. Alumina powder had very low thermal properties due to the presence of large pores and absence of bonding between its particles. Fully dense alumina with a relative density of 99.6 % was obtained at a sintering temperature of 1400°C and a holding time of 10 min. Thermal properties were found to mainly dependent on density. Thermal conductivity, thermal diffusivity, and specific heat of the fully dense alumina were 34.44 W/mK, 7.62 mm2s-1, and 1.22 J/gK, respectively, at room temperature. Thermal conductivity and thermal diffusivity decreased while specific heat increased with the increase in temperature from room temperature to 250ºC.

  16. The mineralogy of bauxite for producing smelter-grade alumina

    Science.gov (United States)

    Authier-Martin, M.; Forte, G.; Ostap, S.; See, J.

    2001-12-01

    Aluminum-producing companies rely on low-cost, high-purity, smelter-grade alumina (aluminum oxide), and alumina production utilizes the bulk of bauxites mined world-wide. The mineralogy of the bauxites has a significant impact on the operation of the Bayer process for alumina production. Typically, the Bayer process produces smelter-grade alumina of 99.5% Al2O3, starting from bauxite containing 30% to 60% Al2O3. The main objective of the Bayer process is to extract the maximum amount of aluminum from the bauxite at as high an aluminate concentration in solution as possible, while limiting any troublesome side reactions. Only with a better understanding of the chemistry of the mineral species and a strict control of the operating/processing conditions can the Bayer process produce efficiently, a low cost, high-quality alumina with minimum detrimental environmental impact.

  17. Microstructural evaluation of alumina-niobium and alumina- niobium-zircon ceramics for ballistic application

    International Nuclear Information System (INIS)

    Mota, Juliana Machado da; Lopes, Cristina Moniz Araujo; Melo, Francisco Lourenco Cristovao de

    2009-01-01

    This study aimed to evaluate the microstructural of Alumina- Niobium and Alumina- Niobium-Zircon ceramics. Samples with 3.5 x 4.5 x 34 mm dimensions were prepared by uniaxial pressure (50 MPa) followed by isostatic pressure (300 MPa). The samples were sintered at 1500 ° C for 1 hour. The ceramics obtained were characterized by scanning electron microscopy (SEM) and X-ray diffraction, to evaluate the phases and microstructures. In order to analyze the microstructure, by SEM the samples were prepared using two techniques: heat treatment (1350 ° C for 5 minutes) and thermochemical treatment (500 ° C for 8 minutes in a solution of NaOH and KOH) on polished and fractured surfaces. The results showed that despite differences between the two etchings, both were effective to analyze the microstructure. (author)

  18. Dissolution kinetics for alumina in cryolite melts. Distribution of alumina in the electrolyte of industrial aluminium cells

    Energy Technology Data Exchange (ETDEWEB)

    Kobbeltvedt, Ove

    1997-12-31

    This thesis contributes to the understanding of which factors determine the rate of dissolution of alumina added to the bath in alumina reduction cells. Knowing this may help reduce the occurrences of operation interruptions and thus make it possible to produce aluminium using less energy. When alumina powder was added to a stirred cryolite melt, the alumina dissolved in two distinct main stages. In the first stage, the dissolution rate was very high, which reflects dissolution of single alumina grains that are being dispersed in the bath upon addition. In the second stage, lumps of alumina infiltrated with bath dissolved at a rate considerably slower than that of the first stage. The formation of these alumina agglomerates is the most important contributor to slow dissolution. The parameters varied in the experiments were convection, batch size, and temperature of the bath and of the added alumina. Increased gas stirring of the bath speeded up dissolution in both stages but the size of the batch was of little significance. Increasing the bath temperature had no effect in the first stage but speeded up dissolution considerably in the second stage. Compared to adding alumina at room temperature, preheating it to a high temperature (600 {sup o}C) increased the dissolution rate in the first stage while preheating to lower temperatures (100-300 {sup o}C) decreased the dissolution rate. In the second stage, preheating slowed the dissolution. The two latter phenomena of reduced dissolution rates are ascribed to the removal of moisture from the alumina upon preheating. The bath flow and the distribution of alumina in the bath were measured in four different types of cells. It was found that if a certain asymmetry of the magnetic field traverse to the cell was present, due to the presence of risers, then loops of high velocity bath flow occurred near the short ends of the cell. Thus, alumina added near the short ends is effectively transferred away from the feeding

  19. Mechanical behavior of alumina and alumina-feldspar based ceramics in an acetic acid (4%) environment

    International Nuclear Information System (INIS)

    Stumpf, Aisha S.G.; Bergmann, Carlos P.; Vicenzi, Juliane; Fetter, Rebecca; Mundstock, Karina S.

    2009-01-01

    This study investigates the mechanical properties of alumina-feldspar based ceramics when exposed to an aggressive environment (acetic acid 4%). Alumina ceramics containing different concentrations of feldspar (0%, 1%, 5%, 10%, or 40%) were sintered at either 1300, 1600, or 1700 o C. Flaws (of width 0%, 30%, or 50%) were introduced into the specimens using a saw. Half of these ceramic bodies were exposed to acetic acid. Their flexural strength, K IC , and porosity were measured and the fractured samples were evaluated using scanning electronic- and optical microscopy. It was found that in the ceramic bodies sintered at 1600 o C, feldspar content up to 10% improved flexural strength and K IC, and reduced porosities. Generally, it was found that acetic acid had a weakening effect on the flexural strength of samples sintered at 1700 o C but a beneficial effect on K IC of ceramics sintered at 1600 o C. It was concluded that alumina-based ceramics with feldspar content up to 10% and sintered at higher temperatures would perform better in an aggressive environment similar to oral cavity.

  20. Special requirements for alumina ceramic of ESG electrode bowl

    Science.gov (United States)

    Zhang, Jun-An; Xue, Kai; Zhang, Jia-Tai; Zhang, Qiang

    2004-06-01

    At present ESG (Electrostatic Suspended Gyro) is the most precise inertia element in the world. The electrode bowl, which has direct effect on the precision of ESG, is a key part to ESG. Through the analysis of the function and characteristic of the electrode bowl in hollow rotor ESG and the present situation of new material development in the world, the alumina ceramic is regarded as the best material for the electrode bowl of hollow rotor ESG. By analyzing the present situation of alumina ceramic in the world, main technique requirements have been put forward for the alumina ceramic of ESG electrode bowl which is also fit for solid rotor ESG.

  1. Master sintering curves of two different alumina powder compacts

    Directory of Open Access Journals (Sweden)

    Vaclav Pouchly

    2009-12-01

    Full Text Available Concept of Master Sintering Curve is a strong tool for optimizing sintering schedule. The sintering behaviour can be predicted, and sintering activation energy can be calculated with the help of few dilatometric measurements. In this paper an automatic procedure was used to calculate Master Sintering Curves of two different alumina compacts. The sintering activation energies were determined as 640 kJ/mol for alumina with particle size of 240 nm, respective 770 kJ/mol for alumina with particle size of 110 nm. The possibility to predict sintering behaviour with the help of Master Sintering Curve was verified.

  2. Dynamical stability of the alpha and theta phases of alumina

    DEFF Research Database (Denmark)

    Lodziana, Zbigniew; Parlinski, K.

    2003-01-01

    Using density functional calculations the phonon dispersion relations, phonon density of states, and free energy of theta and alpha phases of alumina are investigated. The temperature dependence of the free energy indicates that entropy contributes to the destabilization of the alpha phase...... cations in alumina, and suggest that some other than entropic mechanism exists, which stabilizes transition aluminas up to 1400 K. The present calculations go beyond the ground state energy calculations [C. Wolverton and K.C. Hass, Phys. Rev. B 63, 24102 (2001)], and give an additional understanding...

  3. Fabrication of Highly Ordered Gold Nanorods Film Using Alumina Nanopores

    Directory of Open Access Journals (Sweden)

    Z. Soltani

    2012-06-01

    Full Text Available A simple method for fabrication of highly ordered gold nanorod film is introduced in this article. The procedure is based on thermal evaporation of gold into a porous anodic alumina film (PAA. The PPA film was fabricated by combining the hard and mild anodization. This combination effectively decreases the processing time of fabrication of highly ordered porous anodic alumina film with controlled pore diameter and length.  It was found that gold nanorods configuration affected by the porous anodic alumina film structure such as pore diameter and length. Furthermore the evaporation process change the rods diameter along the nanopores via the decreasing the pore mouth during the gold deposition.

  4. Crystallography of Alumina-YAG-Eutectic

    Science.gov (United States)

    Farmer, Serene C.; Sayir, Ali; Dickerson, Robert M.; Matson, Lawrence E.

    2000-01-01

    Multiple descriptions of the alumina-YAG eutectic crystallography appear in the ceramic literature. The orientation between two phases in a eutectic system has direct impact on residual stress, morphology, microstructural stability, and high temperature mechanical properties. A study to demonstrate that the different crystallographic relationships can be correlated with different growth constraints was undertaken. Fibers produced by Laser-Heated Float Zone (LHFZ) and Edge-defined Film-fed Growth (EFG) were examined. A map of the orientation relationship between Al2O3 and Y3Al5O12 and their relationship to the fiber growth axis as a function of pull rate are presented. Regions in which a single orientation predominates are identified.

  5. Aluminum matrix composites reinforced with alumina nanoparticles

    CERN Document Server

    Casati, Riccardo

    2016-01-01

    This book describes the latest efforts to develop aluminum nanocomposites with enhanced damping and mechanical properties and good workability. The nanocomposites exhibited high strength, improved damping behavior and good ductility, making them suitable for use as wires. Since the production of metal matrix nanocomposites by conventional melting processes is considered extremely problematic (because of the poor wettability of the nanoparticles), different powder metallurgy routes were investigated, including high-energy ball milling and unconventional compaction methods. Special attention was paid to the structural characterization at the micro- and nanoscale, as uniform nanoparticle dispersion in metal matrix is of prime importance. The aluminum nanocomposites displayed an ultrafine microstructure reinforced with alumina nanoparticles produced in situ or added ex situ. The physical, mechanical and functional characteristics of the materials produced were evaluated using different mechanical tests and micros...

  6. Optimized alumina coagulants for water treatment

    Science.gov (United States)

    Nyman, May D [Albuquerque, NM; Stewart, Thomas A [Albuquerque, NM

    2012-02-21

    Substitution of a single Ga-atom or single Ge-atom (GaAl.sub.12 and GeAl.sub.12 respectively) into the center of an aluminum Keggin polycation (Al.sub.13) produces an optimal water-treatment product for neutralization and coagulation of anionic contaminants in water. GaAl.sub.12 consistently shows .about.1 order of magnitude increase in pathogen reduction, compared to Al.sub.13. At a concentration of 2 ppm, GaAl.sub.12 performs equivalently to 40 ppm alum, removing .about.90% of the dissolved organic material. The substituted GaAl.sub.12 product also offers extended shelf-life and consistent performance. We also synthesized a related polyaluminum chloride compound made of pre-hydrolyzed dissolved alumina clusters of [GaO.sub.4Al.sub.12(OH).sub.24(H.sub.2O).sub.12].sup.7+.

  7. Glass transition temperature of PMMA/modified alumina nanocomposite: Molecular dynamic study

    OpenAIRE

    Mohammadi, Maryam; Davoodi, Jamal; Javanbakht, Mahdi; Rezaei, Hamidreza

    2017-01-01

    In this study, the effect of alumina and modified alumina nanoparticles in a PMMA/alumina nanocomposite was investigated. To attain this goal, the glass transition behavior of poly methyl methacrylate (PMMA), PMMA/alumina and PMMA/hydroxylated alumina nanocomposites were investigated by molecular dynamic simulations (MD). All the MD simulations were performed using the Materials Studio 6.0 software package of Accelrys. To obtain the glass transition temperature, the variation of density vs. t...

  8. Evaluation of fracture resistance of inlay-retained fixed partial dentures fabricated with different monolithic zirconia materials.

    Science.gov (United States)

    Gumus, Hilal Siriner; Polat, Nilufer Tulin; Yildirim, Guler

    2017-09-29

    Data are lacking on the fracture resistance of monolithic zirconia inlay-retained fixed partial dentures as a conservative treatment for a single missing tooth. The purpose of this in vitro study was to evaluate the fracture resistance of inlay-retained fixed partial dentures produced from 3 different monolithic zirconia materials and based on 2 preparation types and applications with and without thermocycling. A model with missing right and left mandibular first molars was used for different cavity preparations. A tube-shaped cavity and a box-shaped cavity were prepared. Seventy-two epoxy resin casts were prepared from an additional silicone impression. Twenty-four inlay-retained fixed partial dentures from each monolithic zirconia material (Prettau, Zirkonzahn; Katana, Noritake; and Copran, Whitepeaks) were fabricated for each preparation type and cemented to their epoxy model with dual-polymerizing adhesive resin cement; 50% of all specimens were thermocycled for 10000 cycles. The specimens were subjected to a fracture resistance test using a universal testing machine with a crosshead speed of 0.5 mm/min. Fracture surfaces were examined with scanning electron microscopy (SEM), and a specimen from each group was examined for structural changes with differential thermal analysis (DTA). No statistically significant differences in terms of fracture resistance were found among brands with both cavity designs and with and without thermal cycles (P>.05). However, SEM and DTA results showed some changes in monolithic zirconia structure after 1 year of aging. The brands and cavity preparation types for single posterior tooth loss generated similar fracture resistance. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Degree of conversion of luting resins around ceramic inlays in natural deep cavities: a micro-Raman spectroscopy analysis.

    Science.gov (United States)

    Lohbauer, Ulrich; Pelka, Matthias; Belli, Renan; Schmitt, Johannes; Mocker, Eike; Jandt, Klaus D; Müller, Frank A

    2010-01-01

    This study evaluated the degree of conversion (%DC) of luting agents around ceramic inlays placed in deep natural cavities. Thirty-six cylindrical Class I cavities (diameter = 4 mm, depth = 4 mm) were prepared in freshly extracted human teeth and randomly divided according to the luting materials used for luting CAD/CAM fabricated inlays (Empress CAD). The dual-cure resin cements Clearfil Esthetic Cement and Variolink II Low and the light-cure composites Grandio Flow and Grandio were luted using the total-etch technique. The self-adhesive dual-cure cements RelyX Unicem and Maxcem Elite were used as recommended by the manufacturer. All of the restorations were photo-activated using a quartz halogen unit (Elipar TriLight; 750 mW/cm2) for 40 seconds. After 24 hour dry-storage in the dark, all the teeth were vertically sectioned into two halves (n = 12 per group) using a slow-speed diamond-saw in the bucco-vestibular direction under constant water lubrication to avoid specimen heating. The DC of the luting materials was measured by vibrational spectroscopy using a micro-Raman spectrometer at depths of 1, 3 and 4 mm on each side of the tooth halves (n = 24). Disc-shaped samples were produced for measurement of the maximum %DC of each material. Two-way ANOVA and the Student-Newman-Keuls post-hoc test were used in the statistical analysis (alpha = 0.05). All the materials showed no statistical differences in degree of conversion at all tested depths, except for Grandio Flow and Maxcem Elite. Dual-cure and light-cure luting materials showed polymerization homogeneity around ceramic inlays, although dual-cure conventional resin cements tended to show an overall higher conversion.

  10. In vitro evaluation of fracture resistance of teeth restored with ceramic inlays by two undercut elimination techniques

    Directory of Open Access Journals (Sweden)

    Mirzayi M.

    2008-12-01

    Full Text Available "nBackground and Aim: Polymerization shrinkage of resin cements during setting leads to stress on teeth receiving indirect esthetic restorations. Some methods like blocking out undercuts during cavity preparation with glass Ionomer can reduce the mass of resin cement and therefore the amount of stress. The aim of this study was to evaluate the fracture resistance of molar teeth, receiving class I ceramic inlays with two different methods of blocking out undercut. "nMaterials and Methods: In this experimental study, thirty intact molar teeth were randomly divided into three groups of 10 each. One group was maintained intact as the control group. Similar class I cavities with identical undercuts were prepared on the other groups. In group 2 the undercut was filled with light cured glass Ionomer (vitremer 3M before making impression, and in group 3 they were blocked out in the lab before preparation of the inlay. All the teeth in test groups were restored with indirect ceramic inlays.(vitadur - Alpha/ single bond / Rely X ARC. After thermocycling load causing fracture was assessed by universal testing machine. All the specimens were examined under a steriomicroscope (X40 to determine type of fracture. The results were analyzed by one way ANOVA and Tukey HSD tests. P< 0.05 was considered as the level of significance. "nResults: The restored groups showed significantly less fracture resistance than the control group. The difference between two test groups was not significant. The fracture in group2 had less destruction. "nConclusion: According to the findings of this study, blocking out the undercut with two different methods (using glass ionomer/ or blocking it out on the die made no diferrence in fracture resistance.

  11. Effects of ball milling and sintering on alumina and alumina-boron compounds

    Science.gov (United States)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered

  12. Microtensile bond strength between indirect composite resin inlays and dentin: effect of cementation strategy and mechanical aging.

    Science.gov (United States)

    Prochnow, Emília Pithan; Amaral, Marina; Bergoli, César Dalmolin; Silva, Tatiana Bernardon; Saavedra, Guilherme; Valandro, Luiz Felipe

    2014-08-01

    To evaluate the microtensile bond strength of indirect resin composite inlays to dentin using two cementation strategies, before and after mechanical aging. Standardized inlay cavities (bucco-lingual width: 3 mm; depth: 4 mm) were prepared in 32 human premolars. The teeth were embedded in self-curing acrylic resin up to 3 mm from the cementoenamel junction, impressions were made using a polyvinyl siloxane material, master dies were obtained using type 4 stone, and inlay composite resin restorations were fabricated (Sinfony, 3M ESPE). The teeth were randomly allocated into 4 groups according to the cementation strategy (conventional [C] and simplified [S]) and aging (mechanical cycling [MC] and not aged): C[G1]: Adper SingleBond + RelyX ARC without aging; CMC[G2]: conventional cementation + mechanical cycling (106 cycles, 88 N, 4 Hz, ± 37°C); S[G3]: self-adhesive resin cement (RelyX U-100) without aging; SMC[G4] self-adhesive cementation + mechanical cycling. Intaglio surfaces of composite inlays were treated by tribochemical silica coating in G1 and G2, while G3 and G4 received no surface treatment. Non-aged specimens were stored in a moist environment at ca 37°C for the same period as MC (3 days). Non-trimmed beam specimens (bonding area = 1 mm²) were produced by serial cutting, and microtensile testing was performed (0.5 mm/min). Two-way ANOVA showed that the microtensile bond strength was affected only by cementation strategy (p < 0.0001). Tukey's test showed that groups G1 (35.1 ± 9.1) and G2 (32.7 ± 10.7) presented significantly higher bond strength values than G3 (8.7 ± 6.3) and G4 (5.2 ± 4.6). The use of a conventional adhesive technique and tribochemical silica coating resulted in higher μTBS than the one-step simplified cementation, even after mechanical cycling.

  13. Characterization of the Uptake of Nitrogen Oxides on Alumina Adsorbents

    National Research Council Canada - National Science Library

    Pocengal, David

    1999-01-01

    ...) to quantify nitrate and nitrite (NOx) in aqueous solutions that contained NOx exposed alumina and to correlate the quantities of these surface NOx species with the quantity of gaseous NOx sorbed...

  14. Synthesis of α-Alumina (Corundum) and its Application

    International Nuclear Information System (INIS)

    Nay Thwe Kyi; Kyaw Myo Naing; Tin Tin Aye; Nyunt Wynn

    2005-09-01

    This paper described the preparation of aluminium isopropoxide from aluminium sheet at different heating times.Aluminium sheet is found to have a reaction with absolute isopropyl alcohol and mercury (II) chloride as a catalyst under nitrogen atmosphere. Aluminium isopropoxide was characterized by NMR, XRD and IR. Aluminium isopropoxide serves as a molecular precursor to derive pure alumina gel by hydrolysis under both homogeneous and heterogeneous conditions. Pyrolysis to this alumina gel transforms it into -aluminia (corundum) at 1200'C. The phase transformation during pyrolysis was characterized by XRD, SEM and TEM. The alumina (corundum) has porous crystalline nature with high surface aera, which may be used as efficient adsorbent packing material in coloumn chromatography for the seperation of vitamin A from the leaves. -alumina can be also used in catalysis

  15. Surface chloride salt formation on Space Shuttle exhaust alumina

    Science.gov (United States)

    Cofer, W. R., III; Pellett, G. L.; Sebacher, D. I.; Wakelyn, N. T.

    1984-01-01

    Aluminum oxide samples from the exhaust of Space Shuttle launches STS-1, STS-4, STS-5, and STS-6 were collected from surfaces on or around the launch pad complex and chemically analyzed. The results indicate that the particulate solid-propellant rocket motor (SRM) alumina was heavily chlorided. Concentrations of water-soluble aluminum (III) ion were large, suggesting that the surface of the SRM alumina particles was rendered soluble by prior reactions with HCl and H2O in the SRM exhaust cloud. These results suggest that Space Shuttle exhaust alumina particles are good sites for nucleation and condensation of atmospheric water. Laboratory experiments conducted at 220 C suggest that partial surface chloriding of alumina may occur in hot Space Shuttle exhaust plumes.

  16. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  17. Alumina-on-Polyethylene Bearing Surfaces in Total Hip Arthroplasty.

    Science.gov (United States)

    Jung, Yup Lee; Kim, Shin-Yoon

    2010-02-11

    The long-term durability of polyethylene lining total hip arthroplasty (THA) mainly depends on periprosthetic osteolysis due to wear particles, especially in young active patients. In hip simulator study, reports revealed significant wear reduction of the alumina ceramic-on-polyethylene articulation of THA compared with metal-on-polyethylene bearing surfaces. However, medium to long-term clinical studies of THA using the alumina ceramic-on-polyethylene are few and the reported wear rate of this articulation is variable. We reviewed the advantages and disadvantages of ceramicon- polyethylene articulation in THA, hip simulator study and retrieval study for polyethylene wear, in vivo clinical results of THA using alumina ceramic-on-polyethylene bearing surfaces in the literature, and new trial alumina ceramic-onhighly cross linked polyethylene bearing surfaces.

  18. Superhydrophobic alumina surface based on stearic acid modification

    Energy Technology Data Exchange (ETDEWEB)

    Feng Libang, E-mail: lepond@hotmail.com [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China); Zhang Hongxia; Mao Pengzhi; Wang Yanping; Ge Yang [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China)

    2011-02-15

    A novel superhydrophobic alumina surface is fabricated by grafting stearic acid layer onto the porous and roughened aluminum film. The chemical and phase structure, morphology, and the chemical state of the atoms at the superhydrophobic surface were investigated by techniques as FTIR, XRD, FE-SEM, and XPS, respectively. Results show that a super water-repellent surface with a contact angle of 154.2{sup o} is generated. The superhydrophobic alumina surface takes on an uneven flowerlike structure with many nanometer-scale hollows distribute in the nipple-shaped protrusions, and which is composed of boehmite crystal and {gamma}-Al{sub 2}O{sub 3}. Furthermore, the roughened and porous alumina surface is coated with a layer of hydrophobic alkyl chains which come from stearic acid molecules. Therefore, both the roughened structure and the hydrophobic layer endue the alumina surface with the superhydrophobic behavior.

  19. Pressure driven water flow through hydrophilic alumina nanomembranes

    Science.gov (United States)

    Beskok, Ali; Koklu, Anil; Sengor, Sevinc

    2017-11-01

    We present an experimental study that focuses on pressure-driven flow of distilled water through alumina membranes with 5, 10 and 20 nm pore radii. The nanopore geometry, pore size and porosity are characterized using scanning electron microscopy images taken pre and post-flow experiments. Comparisons of these images have shown reduction in the pore size, which is attributed to precipitation of hydroxyl groups on alumina surfaces. Measured flowrates compared with the Hagen-Poiseuille flow relations consistently predict 2.2 nm reductions in the pore size for three different membranes. This behavior can be explained by the formation of a thick stick layer of water molecules over hydroxylated alumina surfaces, evidenced by water droplet contact angle measurements that exhibit increased hydrophilicity of alumina surfaces. Other possible effects of the mismatch between theory and experiments such as unaccounted pressure losses in the system or the streaming potential effects were also considered, but shown to be negligible for current experimental conditions.

  20. Interface chemistry of nanostructured materials: ion adsorption on mesoporous alumina.

    Science.gov (United States)

    Wang, Yifeng; Bryan, Charles; Xu, Huifang; Pohl, Phil; Yang, Yi; Brinker, C Jeffrey

    2002-10-01

    This paper presents a part of our work on understanding the effect of nanoscale pore space confinement on ion sorption by mesoporous materials. Acid-base titration experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. The point of zero charge (PZC) for mesoporous alumina was measured to be approximately 9.1, similar to that for nonmesoporous alumina materials, indicating that nanoscale pore space confinement does not have a significant effect on the PZC of pore surfaces. However, for a given pH deviation from the PZC, (pH-PZC), the surface charge per mass on mesoporous alumina was as much as 45 times higher than that on alumina particles. This difference cannot be fully explained by the surface area difference between the two materials. Our titration data have demonstrated that nanoscale confinement has a significant effect, most likely via the overlap of the electric double layer (EDL), on ion sorption onto mesopore surfaces. This effect cannot be adequately modeled by existing surface complexation models, which were developed mostly for an unconfined solid-water interface. Our titration data have also indicated that the rate of ion uptake by mesoporous alumina is relatively slow, probably due to diffusion into mesopores, and complete equilibration for sorption could take 4-5 min. A molecular simulation using a density functional theory was performed to calculate ion adsorption coefficients as a function of pore size. The calculation has shown that as pore size is reduced to nanoscales (<10 nm), the adsorption coefficients of ions can vary by more than two orders of magnitude relative to those for unconfined interfaces. The prediction is supported by our experimental data on Zn sorption onto mesoporous alumina. Owing to their unique surface chemistry, mesoporous materials can potentially be used as effective ion adsorbents for separation processes and environmental cleanup.

  1. Ceramic joining through reactive wetting of alumina with calcium ...

    Indian Academy of Sciences (India)

    investigations are carried out in non-oxide ceramics such as AlN, Si3N4, SiC etc while ZrO2 and Al2O3 are the usu- ally considered oxide materials for many applications. The literature about alumina joining is very much limited when compared to other ceramics like Si3N4 and SiC. Alumina, both as single crystal and in ...

  2. Alumina-on-Polyethylene Bearing Surfaces in Total Hip Arthroplasty

    OpenAIRE

    Jung, Yup Lee; Kim, Shin-Yoon

    2010-01-01

    The long-term durability of polyethylene lining total hip arthroplasty (THA) mainly depends on periprosthetic osteolysis due to wear particles, especially in young active patients. In hip simulator study, reports revealed significant wear reduction of the alumina ceramic-on-polyethylene articulation of THA compared with metal-on-polyethylene bearing surfaces. However, medium to long-term clinical studies of THA using the alumina ceramic-on-polyethylene are few and the reported wear rate of th...

  3. Short-term visual result after simultaneous photorefractive keratectomy and small-aperture cornea inlay implantation

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2016-11-01

    Full Text Available Majid Moshirfar,1,2 Ryan T Wallace,3 David F Skanchy,4 Jordan D Desautels,5 Steven H Linn,1 Phillip C Hoopes Jr,1 Daniel S Durrie1,6 1Hoopes, Durrie, Rivera, Research Center, Hoopes Vision, Draper, UT, 2Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, 3Brigham Young University, Provo, UT, 4McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 5Tufts University School of Medicine, Boston, MA, 6Durrie Vision, Overland Park, KS, USA Purpose: To report the short-term results of simultaneous photorefractive keratectomy (PRK and small-aperture cornea inlay implantation (KAMRA surgery in treating presbyopia. Methods: Simultaneous PRK and KAMRA inlay surgery was performed on 21 patients from July 2015 to March 2016. Follow-up exams were conducted at 1, 3, and 6 months postoperatively. Our patients were also divided preoperatively into three categories: myopic, hyperopic, and emmetropic. Over the 6-month period, the main outcome measures were uncorrected near visual acuity (UNVA, changes in best-corrected distance visual acuity, and mean spherical equivalent refraction. Results: At 6-month follow-up, 83% (10/12 of patients had a monocular UNVA of 20/40 or better, and 75% had a binocular UNVA of 20/40 (J5 or better. At 6 months, the overall mean refractive spherical equivalent (MRSE was -0.60 D (±0.42 standard deviation [SD], range: -1.38 to -0.13 with a mean change of -0.43 D (±1.19 SD, range: -1.5 to 2.63 compared to preoperative data. Overall, 91% (10/11 of patients were within a ±0.5 D range of our target -0.75 D for KAMRA use. One-hundred percent (5/5 of the hyperopes, 50% (1/2 of emmetropes, and 100% (4/4 of myopes met the targeted range. At 6 months, the MRSE for the hyperopic subgroup (n=5 was 0.33 D (±0.20 SD, the MRSE for the emmetropic subgroup (n=2 was -1.19 D (±0.19 SD, and the MRSE for the myopic

  4. Crack defect formation during manufacture of fused cast alumina refractories

    Science.gov (United States)

    Au, Dominic; Cockcroft, Steve; Maijer, Daan

    2002-07-01

    A sequentially coupled mathematical thermal-stress model, based on the commercial finite-element code ABAQUS, has been developed to rationalize crack defect formation in fused cast αβ-alumina refractories used in the glass industry. The thermal model was validated against thermocouple and pyrometer measurements obtained in an industrial setting. The temperature predictions obtained from the thermal model were employed as input to the elastic strain-rate-independent plastic stress model. The constitutive behavior of αβ-alumina has been determined over a range of temperatures for input to the stress model. The distribution of β-alumina that forms in the center of the casting due to rejection of Na2O during solidifcation was introduced in the stress model through a user-defined subroutine in order to account for the effect of differences in the thermal contraction behavior and elastic modulus of the αβ- and β-alumina phases. The stress analysis indicates that temperature gradients as well as the different dilatational behavior of the αβ- and β-alumina phases are the main drivers of stress and strain evolution during solidification and subsequent cooling. The β-alumina core, in particular, plays an important role in the generation of tensile stresses and likely gives rise to the generation of the internal cracks observed in industrial castings.

  5. Antimicrobial Properties of Chitosan-Alumina/f-MWCNT Nano composites

    International Nuclear Information System (INIS)

    Masheane, M.; Nthunya, L.; Malinga, S.; Masheane, M.; Nthunya, L.; Nxumalo, E.; Mhlanga, S.; Barnard, T.

    2016-01-01

    Antimicrobial chitosan-alumina/functionalized-multi walled carbon nano tube (f-MWCNT) nano composites were prepared by a simple phase inversion method. Scanning electron microscopy (SEM) analyses showed the change in the internal morphology of the composites and energy dispersive spectroscopy (EDS) confirmed the presence of alumina and f-MWCNTs in the chitosan polymer matrix. Fourier transform infrared (FTIR) spectroscopy showed the appearance of new functional groups from both alumina and f-MWCNTs, and thermogravimetric analysis (TGA) revealed that the addition of alumina and f-MWCNTs improved the thermal stability of the chitosan polymer. The presence of alumina and f-MWCNTs in the polymer matrix was found to improve the thermal stability and reduced the solubility of chitosan polymer. The prepared chitosan-alumina/f-MWCNT nano composites showed inhibition of twelve strains of bacterial strains that were tested. Thus, the nano composites show a potential for use as a biocides in water treatment for the removal of bacteria at different environmental conditions.

  6. Superhydrophobic surfaces fabricated by surface modification of alumina particles

    Science.gov (United States)

    Richard, Edna; Aruna, S. T.; Basu, Bharathibai J.

    2012-10-01

    The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.

  7. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  8. Alumina Concentration Detection Based on the Kernel Extreme Learning Machine.

    Science.gov (United States)

    Zhang, Sen; Zhang, Tao; Yin, Yixin; Xiao, Wendong

    2017-09-01

    The concentration of alumina in the electrolyte is of great significance during the production of aluminum. The amount of the alumina concentration may lead to unbalanced material distribution and low production efficiency and affect the stability of the aluminum reduction cell and current efficiency. The existing methods cannot meet the needs for online measurement because industrial aluminum electrolysis has the characteristics of high temperature, strong magnetic field, coupled parameters, and high nonlinearity. Currently, there are no sensors or equipment that can detect the alumina concentration on line. Most companies acquire the alumina concentration from the electrolyte samples which are analyzed through an X-ray fluorescence spectrometer. To solve the problem, the paper proposes a soft sensing model based on a kernel extreme learning machine algorithm that takes the kernel function into the extreme learning machine. K-fold cross validation is used to estimate the generalization error. The proposed soft sensing algorithm can detect alumina concentration by the electrical signals such as voltages and currents of the anode rods. The predicted results show that the proposed approach can give more accurate estimations of alumina concentration with faster learning speed compared with the other methods such as the basic ELM, BP, and SVM.

  9. Influence of additives on the stability of the phases of alumina; Influencia de aditivos na estabilidade das fases da alumina

    Energy Technology Data Exchange (ETDEWEB)

    Rosario, D.C.C.; Gouvea, D., E-mail: deisedorosario@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Metalurgica e de Materiais. Laboratorio de Processos Ceramicos

    2011-07-01

    Problems with the stability of gamma alumina in catalytic reactions have been solved with the inclusion of additives during the synthesis of alumina. These additives stabilize the temperature of phase transition allowing the use of metastable alumina at high temperatures, but the mechanisms of action of additives are not well defined. It is known that each family of additive or additives behaves in different ways for this stabilization. This work aimed to study the performance of MgO and ZrO{sub 2}, respectively at different concentrations in alumina synthesized via Pechini. The samples were analyzed by DSC, X-ray diffraction, measurement of specific surface area by BET analysis, and infrared analysis. The results showed an increase in transition temperature for both additives, and a different changes for specific surface area, showing that MgO and ZrO{sub 2} work on improving the stability but with distinct mechanisms. (author)

  10. The influence of framework design on the load-bearing capacity of laboratory-made inlay-retained fibre-reinforced composite fixed dental prostheses

    NARCIS (Netherlands)

    Keulemans, F.; Lassilla, L.V.J.; Garoushi, S.; Vallittu, P.K.; Kleverlaan, C.J.; Feilzer, A.J.

    2009-01-01

    Delamination of the veneering composite is frequently encountered with fibre-reinforced composite (FRC) fixed dental prosthesis (FDPs). The aim of this study is to evaluate the influence of framework design on the load-bearing capacity of laboratory-made three-unit inlay-retained FRC-FDPs.

  11. In Vitro Comparative Analysis of Fracture Resistance in Inlay Restoration Prepared with CAD-CAM and Different Systems in the Primary Teeth.

    Science.gov (United States)

    Simsek, Huseyin; Derelioglu, Sera

    2016-01-01

    Objective . The aim of this study was to compare to fracture resistance test of inlay restorations prepared using direct inlay technique (Gradia® Direct Composite) and Indirect Restoration System® (Gradia Indirect Composite) and CAD/CAD system (Vita Enamic® Block). Study Design . 48 noncarious extracted maxillary second primary molars were randomly divided into 4 groups with 12 in each group. All the teeth were prepared based on inlay class II preparations except for the control group. Other groups were restored with Gradia Direct Composite, Gradia Indirect Composite, and Vita Enamic Block, respectively. All restorations were cemented self-adhesive dual cure resin (3M Espe, RelyX™ Unicem Aplicap). A fracture test was performed using a compressive load. Results were analyzed using one-way analysis of variance and Duncan's post hoc multiple comparison tests ( α = 0.05). Results . Vita Enamic Block and Gradia Indirect Composite showed significantly higher fracture resistance than Gradia Direct Composite ( p 0.05). All restorations tested led to a significant reduction in fracture resistance ( p inlay restorations, Indirect Restoration Systems and CAD/CAM systems were applied successfully together with the self-adhesive dual cure resin cements in primary molars.

  12. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: An in vitro study

    Directory of Open Access Journals (Sweden)

    Reji P Gopalan

    2018-01-01

    Conclusion: The marginal adaptation of all the three materials used, was well within the acceptable range of 25–70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

  13. Failure above and Below the Elastic Limit in AD995

    Science.gov (United States)

    Bourne, N. K.; Millett, J. C. F.; Chen, M. W.; Dandekar, D. P.; McCauley, J. W.

    2007-12-01

    There is an ongoing interest in identifying inexpensive armour materials for use in the protection of personnel and vehicles. The response of AD995 under shock loading is one of the materials most extensively investigated. Over recent years, workers have reported failure occurring in various polycrystalline ceramics behind the shock front. This phenomenon has been investigated using embedded stress sensors and a recovery technique that has allowed observation of the microstructure above and below the Hugoniot Elastic Limit (HEL) and these results are brought together here to explain the observed behaviour. The failure front velocity is found to change with the applied stress, in particular it slows as the HEL is exceeded. The microstructure shows the response below the HEL is dominated by intergranular failure whilst above it, the grains exhibit plasticity (including twinning). The HEL is thus shown to be characteristic of alumina viewed as a composite with randomly oriented alumina grains.

  14. Intermetallic Strengthened Alumina-Forming Austenitic Steels for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bin [Dartmouth College, Hanover, NH (United States); Baker, Ian [Dartmouth College, Hanover, NH (United States)

    2016-03-31

    In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, the materials required must be strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and L12 precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The creep resistance of these alloys is significantly improved through intermetallic strengthening (Laves-Fe2Nb + L12-Ni3Al precipitates) without harmful effects on oxidation resistance. Microstructural and microchemical analyses of the recently developed alumina-forming austenitic (AFA) steels (Fe-14Cr-32Ni-3Nb-3Al-2Ti-based) indicated they are strengthened by Ni3Al(Ti) L12, NiAl B2, Fe2Nb Laves phase and MC carbide precipitates. Different thermomechanical treatments (TMTs) were performed on these stainless steels in an attempt to further improve their mechanical properties. The thermo-mechanical processing produced nanocrystalline grains in AFA alloys and dramatically increased their yield strength at room temperature. Unfortunately, the TMTs didn’t increase the yield strengths of AFA alloys at ≥700ºC. At these temperatures, dislocation climb is the dominant mechanism for deformation of TMT alloys according to strain rate jump tests. After the characterization of aged AFA alloys, we found that the largest strengthening effect from L12 precipitates can be obtained by aging for less than 24 h. The coarsening behavior of the L12 precipitates was not influenced by carbon and boron additions. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these AFA steels after creep tests. Though the Laves and B2-NiAl phase precipitated along the boundaries can improve the creep properties, cracks were

  15. Coprecipitated nickel-alumina methanation catalysts

    International Nuclear Information System (INIS)

    Kruissink, E.C.

    1981-01-01

    In the last few years there has been a renewed interest in the methanation reaction CO+3H 2 =CH 4 +H 2 O. The investigations described in this thesis were performed in relation to the application of this reaction, within the framework of the so-called 'NFE' project, also called 'ADAM' and 'EVA' project. This project, which has been under investigation in West Germany for some years, aims at the investigation of the feasibility of transporting heat from a nuclear high temperature reactor by means of a chemical cycle. A promising possibility to realize such a cycle exists in applying the combination of the endothermic steam reforming of methane and the exothermic methanation reaction. This thesis describes the investigations into a certain type of methanation catalyst, viz. a coprecipitated nickel-alumina catalyst, with the aim to give more insight into the interrelationship between the preparation conditions on the one hand and catalyst properties such as activity and stability on the other hand. (Auth.)

  16. Six-month visual outcomes for the correction of presbyopia using a small-aperture corneal inlay: single-site experience

    Science.gov (United States)

    Moshirfar, Majid; Quist, Tyler S; Skanchy, David F; Wallace, Ryan T; Linn, Steven H; Hoopes, Phillip C

    2016-01-01

    Objective The objective of this study was to describe 6-month postoperative efficacy and safety outcomes after monocular KAMRA corneal inlay implantation in emmetropic presbyopic patients. Study design This study followed a retrospective chart analysis. Setting This study was performed at Hoopes Vision in Draper, UT, USA. Subjects and methods Fifty-seven patients met the inclusion criteria of this study and underwent KAMRA corneal inlay implantation following the approval of the United States Food and Drug Association between May 2015 and April 2016 at a single site. Surgery involved femtosecond laser-created corneal pockets of various depths. Efficacy, safety, and patient satisfaction reports were analyzed at 3 and 6 months. Results At 6 months follow-up, the monocular uncorrected near visual acuity (UNVA) was Jaeger (J) 4 (20/32), the mean uncorrected distance visual acuity was 20/25, and the mean corrected distance visual acuity was 20/20. At 6 months, 71% of patients with a pocket depth of ≥250 μm had a UNVA of 20/20 or better, whereas only 22% of patients with a shallow pocket depth of inlay recentration, all of which resulted in improved visual acuity. At 6 months, 72% of patients reported some level of satisfaction, 26% of patients reported being “not dependent” on reading glasses, and 62% of patients reported being able to do most things in bright light without reading glasses. Conclusion For patients with emmetropic presbyopia, the KAMRA inlay is a viable treatment option resulting in improved UNVA. Increased pocket depth may be associated with better postoperative outcomes. Safety rates are high, while explantation and recentering rates are low. Overall, patient satisfaction of the KAMRA inlay is good. PMID:27843289

  17. Moisture-Induced Delayed Alumina Scale Spallation on a Ni(Pt)Al Coating

    Science.gov (United States)

    Smialek, James L.

    2009-01-01

    Delayed interfacial scale failure takes place after cooling for samples of a Ni(Pt)Al-coated CMSX4 single crystal superalloy, cycled at 1150 C for up to 2000 hr. One sample exhibited premature coating grain boundary wrinkling, alumina scale spallation to bare metal, and a final weight loss of 3.3 mg/cm2 . Spallation under ambient conditions was monitored with time after cooldown and was found to continue for 24 hr. This produced up to 0.05 mg/cm2 additional loss for each hold, accumulating 0.7 mg/cm 2 (20 percent of the total) over the course of the test. After test termination, water immersion produced an additional 0.15 mg/cm2 loss. (A duplicate sample produced much less wrinkling and time dependent spalling, maintaining a net weight gain.) The results are consistent with the general phenomena of moisture-induced delayed spallation (MIDS) of mature, distressed alumina scales formed on oxidation resistant M-Al alloys. Relative ambient humidity is discussed as the factor controlling adsorbed moisture, reaction with the substrate, and hydrogen effects on interface strength.

  18. A Study on Calcium Transfer from Slag to Steel and its Effect on Modification of Alumina and Spinel Inclusions

    Science.gov (United States)

    Kumar, Deepoo; Pistorius, P. Chris

    Aluminum deoxidized steel tends to form solid inclusions (alumina, spinel, partially modified calcium aluminates). These solid inclusions are known to present challenges during casting, cause slivers during mechanical working and act as crack initiation sites for mechanical failure. Calcium injection practice has been used by the industry to transform these solid inclusions into liquid inclusions for several decades. There has been a significant amount of study to understand the mechanism of calcium modification of alumina/spinel inclusions. However, there has been little attempt to understand calcium transfer from slag to steel to inclusions that may modify alumina inclusions. In this study, laboratory deoxidation experiments were conducted using an induction furnace, physically simulating a ladle furnace; samples were taken during these experiments to study the extent of calcium transfer through inclusion analysis. This study shows that in the presence of silicon, there can be significant amount of calcium transfer from slag. Also, as the rate of calcium transfer from slag is limited by mass transfer in steel and slag, it is difficult to modify a large concentration of inclusions. However, an appreciable extent of calcium transfer was found in the case of lower concentration of inclusions (less than 150 ppm area fraction).

  19. Kidney Failure

    Science.gov (United States)

    ... enough red blood cells. This is called kidney failure. If your kidneys fail, you need treatment to ... providers, family, and friends, most people with kidney failure can lead full and active lives. NIH: National ...

  20. Respiratory Failure

    Science.gov (United States)

    Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, such as ... need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can't ...

  1. Heart Failure

    DEFF Research Database (Denmark)

    Jorsal, Anders; Wiggers, Henrik; McMurray, John J V

    2018-01-01

    This article briefly discusses the epidemiology of heart failure and diabetes and summarizes the key findings from the recent cardiovascular outcome trials in patients with type 2 diabetes, with a focus on heart failure as an endpoint.......This article briefly discusses the epidemiology of heart failure and diabetes and summarizes the key findings from the recent cardiovascular outcome trials in patients with type 2 diabetes, with a focus on heart failure as an endpoint....

  2. Heart Failure

    Science.gov (United States)

    Heart failure is a condition in which the heart can't pump enough blood to meet the body's needs. Heart failure does not mean that your heart has stopped ... and shortness of breath Common causes of heart failure are coronary artery disease, high blood pressure and ...

  3. Efficiency of Nepheline Ore Processing for Alumina Production

    Science.gov (United States)

    Arlyuk, B. I.; Pivnev, A. I.

    The comparative economical analysis and energetic analysis of alumina production from various kinds of raw materials were carried out basing on industrial data. The main process parameters of nepheline raw materials processing through sintering adopted at large industrial scale are given. The said technology allows the wasteless utilization of nepheline to produce alumina, soda, potash, potassium sulphate and chloride, portland cement and gallium without polluting the environment. According to industrial data the production cost of alumina while using the sintering of nepheline raw material is considerably lower than in processing of high grade bauxites by the Bayer way due to complete utilization of wastes, and as for capital investments into the process facilities they are lower than those into alumina production from bauxites, production of soda, potash and cement by traditional methods taken together. Are cited the flowsheets of alumina, soda, potash and portland cement production from nepheline ore, the process interrelationships determining the efficiency of raw material processing, and ways of further improvement of the process.

  4. Early wound healing and refractive response of different pocket configurations following presbyopic inlay implantation.

    Directory of Open Access Journals (Sweden)

    Aris Konstantopoulos

    Full Text Available Presbyopic inlays have mostly been implanted under a corneal flap. Implantation in a pocket has advantages including less postoperative dry eye and neurotrophic effect, and better biomechanical corneal stability. This study investigated the effect of different pocket and flocket dimensions on corneal stability and refractive power after Raindrop™ implantation, and the associated wound healing response.Ten New Zealand White rabbits had bilateral pocket Raindrop™ implantation. Eyes were allocated to 4 groups: pockets with 4mm, 6mm, and 8mm diameters, and 8mm flocket. They were examined pre-operatively, at day 1, weeks 1, 2, 3 and 4 post-surgery with anterior segment optical coherence tomography, corneal topography and in-vivo confocal microscopy. After euthanasia (week 4, CD11b, heat shock protein (HSP 47 and fibronectin corneal immunohistochemistry was performed.Corneal thickness (mean±SD increased from 360.0±16.2μm pre-operatively to 383.9±32.5, 409.4±79.3, 393.6±35.2, 396.4±50.7 and 405±20.3μm on day 1, weeks 1,2,3 and 4 respectively (p<0.008, all time-points. Corneal refractive power increased by 11.1±5.5, 7.5±2.5, 7.5±3.1, 7.0±3.6 and 6.3±2.9D (p<0.001. Corneal astigmatism increased from 1.1±0.3D to 2.3±1.6, 1.7±0.7, 1.8±1.0, 1.6±0.9 and 1.6±0.9D respectively (p = 0.033. CT, refractive power change and astigmatism were not different between groups. The 8mm pocket and 8mm flocket groups had the least stromal keratocyte reflectivity. CD11b, fibronectin or HSP47 weren't detected.Anatomical and refractive stability was achieved by 1 week; the outcomes were not affected by pocket or flocket configuration. No scarring or inflammation was identified. The 8mm pocket and flocket showed the least keratocyte activation, suggesting they might be the preferred configuration.

  5. Early wound healing and refractive response of different pocket configurations following presbyopic inlay implantation

    Science.gov (United States)

    Konstantopoulos, Aris; Liu, Yu-Chi; Teo, Ericia Pei Wen; Lwin, Nyein Chan; Yam, Gary Hin Fai; Mehta, Jodhbir S.

    2017-01-01

    Background Presbyopic inlays have mostly been implanted under a corneal flap. Implantation in a pocket has advantages including less postoperative dry eye and neurotrophic effect, and better biomechanical corneal stability. This study investigated the effect of different pocket and flocket dimensions on corneal stability and refractive power after Raindrop™ implantation, and the associated wound healing response. Methodology Ten New Zealand White rabbits had bilateral pocket Raindrop™ implantation. Eyes were allocated to 4 groups: pockets with 4mm, 6mm, and 8mm diameters, and 8mm flocket. They were examined pre-operatively, at day 1, weeks 1, 2, 3 and 4 post-surgery with anterior segment optical coherence tomography, corneal topography and in-vivo confocal microscopy. After euthanasia (week 4), CD11b, heat shock protein (HSP) 47 and fibronectin corneal immunohistochemistry was performed. Results Corneal thickness (mean±SD) increased from 360.0±16.2μm pre-operatively to 383.9±32.5, 409.4±79.3, 393.6±35.2, 396.4±50.7 and 405±20.3μm on day 1, weeks 1,2,3 and 4 respectively (p<0.008, all time-points). Corneal refractive power increased by 11.1±5.5, 7.5±2.5, 7.5±3.1, 7.0±3.6 and 6.3±2.9D (p<0.001). Corneal astigmatism increased from 1.1±0.3D to 2.3±1.6, 1.7±0.7, 1.8±1.0, 1.6±0.9 and 1.6±0.9D respectively (p = 0.033). CT, refractive power change and astigmatism were not different between groups. The 8mm pocket and 8mm flocket groups had the least stromal keratocyte reflectivity. CD11b, fibronectin or HSP47 weren’t detected. Conclusions Anatomical and refractive stability was achieved by 1 week; the outcomes were not affected by pocket or flocket configuration. No scarring or inflammation was identified. The 8mm pocket and flocket showed the least keratocyte activation, suggesting they might be the preferred configuration. PMID:28235010

  6. Zirconia-alumina composites of high mechanical strength

    International Nuclear Information System (INIS)

    Pyda, W.; Pyda, A.

    2004-01-01

    Commercial zirconia (stabilized with 3 mol% yttria) and alumina powders of submicron size were used to produce ceramic matrix composites in the ZrO 2 -Al 2 O 3 system. Homogeneous mixtures of both constituent powders were prepared by means pf physical mixing in water exploiting a heterofloculation effect. The mixtures were consolidated using two methods: (i). Cold isostatic pressing of the samples under 300 MPa followed by pressureless sintering in air, (ii). hot pressing under 25 MPa in argon. The samples were sintered for 2 h at 1500-1650 o C. Detailed characterization was made with respect of the powder properties, packing of the particles in green compacts and microstructure of the consolidated composites. Studied was an influence of alumina content and the consolidation method on mechanical properties of the composites. A bending strength of 17±0.2 GPa was measured for the TZP material which contained 5 vol.% of alumina particles. (author)

  7. Retrospective dosimetry with alumina substrate from electronic components

    International Nuclear Information System (INIS)

    Ekendahl, D.; Judas, L.

    2012-01-01

    Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses. (authors)

  8. Modifying alumina red mud to support a revegetation cover

    Science.gov (United States)

    Xenidis, A.; Harokopou, A. D.; Mylona, E.; Brofas, G.

    2005-02-01

    Alumina red mud, a fine-textured, iron-rich, alkaline residue, is the major waste product of bauxite digestion with caustic soda to remove alumina. The high alkalinity and salinity as well as the poor nutrient status are considered to be the major constraints of red mud revegetation. This research was conducted to evaluate the ameliorating effect of gypsum, sewage sludge, ferrous sulfate, ammonium sulfate, ammonium nitrate, and calcium phosphate on alumina red mud. The effectiveness of the mixtures was evaluated by applying extraction tests and performing experiments using six plant species. Gypsum amendment significantly reduced the pH, electrical conductivity, and sodium and aluminum content of red mud. Sewage sludge application had an extended effect in improving both the soil structure and the nutrient status of the gypsum-amended red mud. Together with the gypsum and sewage sludge, calcium phosphate application into red mud enhanced plant growth and gave the most promising results.

  9. Pressureless sintering behavior of injection molded alumina ceramics

    Directory of Open Access Journals (Sweden)

    Liu W.

    2014-01-01

    Full Text Available The pressureless sintering behaviors of two widely used submicron alumina (MgOdoped and undoped with different solid loadings produced by injection molding have been studied systematically. Regardless of the sinterability of different powders depending on their inherent properties, solid loading plays a critical role on the sintering behavior of injection molded alumina, which greatly determines the densification and grain size, and leads to its full densification at low temperatures. As compared to the MgO-doped alumina powder, the undoped specimens exhibit a higher sinterability for its smaller particle size and larger surface area. While full densification could be achieved for MgO-doped powders with only a lower solid loading, due to the fact that MgO addition can reduce the detrimental effect of the large pore space on the pore-boundary separation.

  10. Membranes obtained from alumina from separation water/oil

    International Nuclear Information System (INIS)

    Rosas Neto, M.I.; Lira, H.L; Guimaraes, I.O; Franca, K.B.

    2016-01-01

    This study aims to evaluate by flow test emulsion water/oil a membrane obtained from a crude residue of the alumina industry and see if this membrane is able to filter this emulsion within the limits specified by CONAMA. In this work, tubular membranes composed of the alumina and the residue bentonite clay were produced by extrusion and were sintered at 900, 1000 and 1100 ° C. tangential flow tests were conducted with deionized water and subsequently with an emulsion of water / oil, all done with a pressure of 1.5 bar. The results showed that membranes produced from the crude residue the alumina industry were quite efficient the emulsion's oil removal, reducing the concentration of about 100 ppm in the feed, to below 5ppm and flow rates of around 30L/h.m 2 . (author)

  11. Radiation silver paramagnetic centers in a beta-alumina crystal

    International Nuclear Information System (INIS)

    Badalyan, A.G.; Zhitnikov, R.A.

    1985-01-01

    Silver paramagnetic centers in a β-alumina crystal, formed after X-ray radiation at 77 K, are investigated by the EPR method. Silver enters the β-alumina crystal, substituting sodium and potassium ions in a mirror plane. Crystals with substitution from 0.1 to 100% of alkali metal ions by Ag + ions are investigated. Silver atomic centers (Ag 0 -centers), formed by electron capture with the Ag + ion, are firstly detected and investigated in the β-alumina. Hole Ag 2+ -centers are investigated and detected in crystals with high concentration of Ag + . By studying the orientation dependence of a g-factor it is established that hole capture by the Ag + ion is accompanied by Ag 2+ ion displacement from the position, Ag + being primarity taken up (Beavers-Roth or anti- Beavers-Roth) to the position between two oxygen ions in the mirror plane

  12. Synthesis of alumina powders by precipitation method and solvothermal treatment

    International Nuclear Information System (INIS)

    Politchuk, J.O.; Lima, N.B.; Lazar, D.R.R.; Ussui, V.; Yoshito, W.K.

    2012-01-01

    The improvement of alumina powders synthesis processes has been focused on the preparation of ceramic powders with well defined crystalline structure and with high specific surface area and nanometric particle size without formation of hard agglomerates. For this purpose the precipitation step should be studied and and also the temperature of alumina crystallization should be reduced. The aim of this study was to obtain alumina powders by hydroxide precipitation with ammonia in the presence of cationic surfactant, followed by solvothermal treatment and calcination. The powders were characterized by TG/DTA, X-ray diffraction, surface area measurements by gas adsorption (BET) and scanning electron microscopy. The results showed that powders produced by solvothermal treatment without surfactant have higher crystallinity. However the presence of CTAB enhances 240% the specific surface area compared with powders produced without this reagent (author)

  13. Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, University of Tunis Elmanar 2092 Tunis (Tunisia); Harima, N.; Koyama, H. [Hyogo University of Teacher Education, Kato, Hyogo 673-1494 (Japan); Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus)

    2012-09-15

    We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA. - Highlights: Black-Right-Pointing-Pointer Porous anodic alumina-rhodamine 110 nanocomposites are elaborated. Black-Right-Pointing-Pointer Efficient energy transfer from the host to Rh110 molecules is evidenced from measurements of photoluminescence and degree of polarization memory spectra. Black-Right-Pointing-Pointer Thermal annealing of porous anodic alumina can improve the process of excitation transfer.

  14. Two steps sintering alumina doped with niobia; Sinterizacao em duas etapas de alumina aditivada com niobia

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, L.B.; Hatzfeld, J.; Heck, M.; Pokorny, A.; Bergmann, C.P., E-mail: lucas.gomes@ufrgs.br [Universidade Federal do Rio Grande do Sul (LACER/UFRGS) Porto Alegre, RS (Brazil). Laboratorio de Materiais Ceramicos

    2014-07-01

    In this work, high surface area commercial alumina was doped with niobia and sintered in two steps in order to obtain dense materials with lower processing temperatures. The powders were milled and uniaxially pressed (200 MPa). The first step of sintering took place at 1100°C for 3, 6, 9 and 12 hours, followed by the second step at 1350°C for 3 hours. The relative density, porosity and water absorption of the samples were determined by the Archimedes method. The crystalline phases were analyzed by X-ray Diffraction (XRD) and the morphology of the samples after sintering, evaluated by Scanning Electron Microscopy (SEM). The results indicate that the use of niobia combined with the two steps sintering promotes an increase in the density of the material, even at lower sintering temperatures. (author)

  15. Distribution of nickel between copper-nickel and alumina saturated iron silicate slags

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, R.G.; Acholonu, C.C.

    1984-03-01

    The solubility of nickel in slag is determined in this article by equilibrating copper-nickel alloys with alumina-saturated iron silicate slags in an alumina crucible at 1573 K. The results showed that nickel dissolves in slag both as nickel oxide and as nickel metal. The presence of alumina is shown to increase the solubility of nickel in slags.

  16. Cylindrical Three-Dimensional Porous Anodic Alumina Networks

    Directory of Open Access Journals (Sweden)

    Pedro M. Resende

    2016-11-01

    Full Text Available The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates.

  17. Controllable synthesis and characterization of alumina/MWNT nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Nemeth, Zoltan; Hernadi, Klara [Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Bela ter 1, 6720 Szeged (Hungary); Marko, Kata; Erdohelyi, Andras [Department of Physical Chemistry and Material Science, University of Szeged, Aradi ter 2, 6720 Szeged (Hungary); Forro, Laszlo [Laboratory of Physics of Complex Matter, IPMC, EPFL, 1026 Ecublens (Switzerland)

    2011-11-15

    The aim of this work is to develop a controllable synthesis pathway which produces a stable alumina layer on the surface of carbon nanotubes by impregnation method. Precursor compounds such as aluminium isopropoxide and aluminium-acetyl-acetonate were used to cover the surface of multiwalled carbon nanotubes (MWNTs) under different solvent conditions. As-prepared alumina coverages were characterized by TEM, SEM, SEM-EDX, TG and X-ray diffraction techniques. Results revealed that homogeneous coverage can be achieved in a controllable way. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. A comparison of stresses in molar teeth restored with inlays and direct restorations, including polymerization shrinkage of composite resin and tooth loading during mastication.

    Science.gov (United States)

    Dejak, Beata; Młotkowski, Andrzej

    2015-03-01

    Polymerization shrinkage of composites is one of the main causes of leakage around dental restorations. Despite the large numbers of studies there is no consensus, what kind of teeth reconstruction--direct or indirect composite restorations are the most beneficial and the most durable. The aim was to compare equivalent stresses and contact adhesive stresses in molar teeth with class II MOD cavities, which were restored with inlays and direct restorations (taking into account polymerization shrinkage of composite resin) during simulated mastication. The study was conducted using the finite elements method with the application of contact elements. Three 3D models of first molars were created: model A was an intact tooth; model B--a tooth with a composite inlay, and model C--a tooth with a direct composite restoration. Polymerization linear shrinkage 0.7% of a direct composite restoration and resin luting cement was simulated (load 1). A computer simulation of mastication was performed (load 2). In these 2 situations, equivalent stresses according to the modified von Mises criterion (mvM) in the materials of mandibular first molar models with different restorations were calculated and compared. Contact stresses in the luting cement-tooth tissue adhesive interface around the restorations were also assessed and analyzed. Equivalent stresses in a tooth with a direct composite restoration (the entire volume of which was affected by polymerization shrinkage) were many times higher than in the tooth restored with a composite inlay (where shrinkage was present only in a thin layer of the luting cement). In dentin and enamel the stress values were 8-14 times higher, and were 13 times higher in the direct restoration than in the inlay. Likewise, contact stresses in the adhesive bond around the direct restoration were 6.5-7.7 times higher compared to an extraorally cured restoration. In the masticatory simulation, shear contact stresses in the adhesive bond around the direct

  19. Physical properties of dual-cured luting-agents correlated to early no interfacial-gap incidence with composite inlay restorations.

    Science.gov (United States)

    Irie, Masao; Maruo, Yukinori; Nishigawa, Goro; Suzuki, Kazuomi; Watts, David C

    2010-06-01

    The aims of this investigation were to investigate dual-cured luting-agents as to whether their bond strength, dimensional change and flexural modulus influence no interfacial-gap incidence parameters of composite inlay restorations during the early stages. The correlations of interest were between: (a) their shear bond strength to dentin, (b) their dimensional change on setting, (c) their flexural modulus, and (d) no interfacial-gap incidence with indirect restorations. Seven dual-cured luting-agents, one self-adhesive resin cement, six resin cements and one resin-modified glass-ionomer for luting, were investigated with specimen sub-groups (n=10) for each property measured. The principal series of experiments were conducted in dentin cavities with interfacial polishing either immediately (3 min) after setting or after 1-day water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of interfacial-gaps was measured (and then summed for each cavity) at 14 points (each 0.5mm apart) along the composite inlay restoration interface (n=10 per group; total points measured=140), and was expressed by percentage of measured total points. The shear bond strengths to dentin, setting shrinkage-strain and flexural modulus were measured. To estimate the dimensional change of luting-agents, the maximum marginal gap-width and the opposing-width that occurred with luting-agents in a Teflon mold were measured. Moduli were measured in 3-point bending. For all composite inlay restorations, polished immediately after setting, an incidence of summed no-gaps of 69-88% was observed. For specimens polished after 1 day, a significantly (p0.05). There was a highly significant correlation between no interfacial-gap incidence and shear bond strength (r=0.702, p=0.002, n=16). As the dimensional change (shrinkage) within Teflon molds increased, the no interfacial-gap incidence of dentin/inlay

  20. Restoration of non-carious cervical lesions with ceramic inlays: A possible model for clinical testing of adhesive cements

    Directory of Open Access Journals (Sweden)

    Michal Staninec

    2012-01-01

    Full Text Available Introduction: There are many luting cements coming to market which claim to be adhesive, but there is no clinical protocol currently for testing these claims. There is a standardized protocol for testing direct restorations bonded to dentin and it is used extensively. Case Report: We describe a clinical procedure for restoring a non-carious cervical lesion (NCCL with a ceramic inlay using Computer-Aided Design and Computer-Aided Manufacturing (CAD-CAM technology and an adhesive resin cement.The procedure was straightforward and the result was good at one month. Discussion: NCCL′s can be restored with CAD-CAM technology in one appointment. This technique can be used to clinically test adhesion of luting cements to dentin, similarly to the current standard for direct restorations.

  1. INLAY method using the cylindrical container for reactor vessel outlet nozzle of PWR for Ohi Nuclear Power Station

    International Nuclear Information System (INIS)

    Ichiki, Shigeki; Iwahashi, Hiroki; Terada, Norio; Nakamura, Yasuo; Yamamoto, Kazuhide

    2010-01-01

    Preventive maintenance techniques against PWSCC found in Alloy 600 welds have been applied progressively, however, in February 2008, a defect of PWSCC had been found in an outlet nozzle to safe-end weld of Reactor vessel of PWR in Ohi Nuclear Power Station Unit 3 during an outage. Then the defect was removed and after its safety was confirmed, the unit was placed in operation. In the next outage, INLAY method using the cylindrical container was applied and repair welding for the removed part was performed. In addition, circumferential grooving to remove Alloy 600 of the inner surface of the outlet nozzle and circumferential welding with PWSCC resistant Alloy 690 were applied. This circumferential grooving and welding techniques were also applied for all outlet nozzles of Ohi Unit 4 as a preventive maintenance. (author)

  2. Influence of different composite materials and cavity preparation designs on the fracture resistance of mesio-occluso-distal inlay restoration.

    Science.gov (United States)

    Tekçe, Neslihan; Pala, Kansad; Demirci, Mustafa; Tuncer, Safa

    2016-01-01

    The aim of the study to evaluate the fracture resistance of a computer-aided design/computer-aided manufacturing (CAD/CAM) and three indirect composite materials for three different mesio-occluso-distal (MOD) inlay cavity designs. A total of 120 mandibular third molar were divided into three groups: (G1) non-proximal box, (G2) 2-mm proximal box, and (G3) 4-mm proximal box. Each cavity design received four composite materials: Estenia, Epricord (Kuraray, Japan), Tescera (Bisco, USA), and Cerasmart CAD/CAM blocks (GC, USA). The specimens were subjected to a compressive load at a crosshead speed of 1 mm/min. The data was analyzed using the two-way analysis of variance and Bonferroni post hoc test (pinlay restoration.

  3. Five-year clinical outcome of posterior zirconia ceramic inlay-retained FDPs with a modified design.

    Science.gov (United States)

    Chaar, M Sad; Kern, Matthias

    2015-12-01

    To evaluate the 5-year clinical outcome of posterior inlay-retained fixed dental prostheses (IRFDPs) with a modified design made from zirconia ceramic (Vita In-Ceram YZ, Vita Zahnfabrik, Bad Säckingen, Germany). Thirty 3-unit IRFDPs were placed in 30 patients. Seven IRFDPs replaced the second premolars (4 in the maxilla, 3 in the mandible), and 23 replaced the first molars (15 in the maxilla, 8 in the mandible). Preparations were performed in accordance with general principles for ceramic inlay restorations and modified with a short retainer-wing bevel preparation within the enamel at the buccal and oral sides. The frameworks were milled from zirconia ceramic, and the pontics were veneered with feldspathic ceramic. After air-abrasion of bonding surfaces, IRFDPs were bonded with an adhesive composite resin. The patients were recalled 6-12 months after placement, and then annually. Kaplan-Meier analysis was used to calculate the survival and complication rates of the IRFDPs. After a mean observation time of 64.4 (SD=17.6) months (min 15, max 95.6), the 5-year cumulative survival of IRFDPs was 95.8%. Debonding was reported for two IRFDPs (6.9%), one of them failed finally after 49.4 months due to repeated debonding. Chipping of the veneering ceramic was reported in three cases (10.5%). Secondary caries were reported in 2 patients (8.1%). Nevertheless, the latter complications did not affect the clinical function of the involved IRFDPs. The 5-year clinical outcome of zirconia-based IRFDPs fabricated in the modified design is encouraging, so that they may represent a treatment alternative to replace posterior single missing teeth, taking into consideration the appropriate case selection. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. All-ceramic inlay-retained fixed dental prostheses for replacing posterior missing teeth: A systematic review.

    Science.gov (United States)

    Castillo-Oyagüe, Raquel; Sancho-Esper, Rocío; Lynch, Christopher D; Suárez-García, María-Jesús

    2018-01-01

    To evaluate the current status of all-ceramic inlay-retained fixed dental prostheses (CIR-FDPs) for the replacement of posterior teeth. Screening of titles and abstracts, full-text analysis for inclusion eligibility, quality assessment, data extraction and evaluation of the scientific evidence were performed independently by two reviewers. The electronic databases MEDLINE/PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Compludoc were searched with no restriction to publication date or language. The quality of the studies was evaluated through: the original 'QDP' ('Questionnaire for selecting articles on Dental Prostheses') (for research papers); the 'Guidelines for managing overviews' of the Evidence-Based Medicine Working Group (for reviews); the Cochrane risk of bias tool; and the GRADE scale for grading scientific evidence. This review started with 4942 articles, which were narrowed down to 23 according to the selection criteria. The data was not statistically treated because of the heterogeneity of the studies. Zirconia-based CIR-FDPs may be recommended for restoring posterior single missing teeth, although the prosthesis/tooth bonded interface has yet to be improved. The addition of lateral wings to the classical inlay preparation seems promising. The weakest parts of CIR-FDPs are the connectors and retainers, while caries and endodontic problems are the most common biological complications. The fabrication of CIR-FDPs with monolithic zirconia may eliminate chipping problems. A three-unit CIR-FDP is a viable treatment option for replacing a posterior missing tooth. Appropriate case selection, abutment preparation and luting procedures may be decisive for clinical success. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  5. Effect of Impurities on O and Al Boundary Diffusion in Alumina: Application Alumina Scale Growth in Alloys

    Science.gov (United States)

    2012-01-24

    500ppm Hafnium doped E 3 25000 01 20000 re 0- • 1250 Q. 15000 • 1400 c 10000 O re •0 ’x 5000 O " K- =1.70*10 15 mVs —• 0 1...jjp, 25000 I s3 20000 15000 10000 5000 Lxperimental data (1300°C 60 h) - Fitting using the quasi steady-state model • Fitting using the...c o I 01 > 3 E 3 Comparison between Yttrium doped and Pur« alumina -•-Yttrium doped -•-Pure alumina 100 110 120 130 140 ISO

  6. High-frequency characteristics of glass/ceramic composite and alumina multilayer structures

    International Nuclear Information System (INIS)

    Niwa, K.; Suzuki, H.; Yokoyama, H.; Kamechara, N.; Tsubone, K.; Tanisawa, H.; Sugiki, H.

    1990-01-01

    This paper reports the transmission characteristics of glass/ceramic composite (borosilicate glass/alumina) and alumina multilayer structures examined. The triplate stripline formed in the glass/ceramic multilayer shows low conductor and dielectric loss. Alumina multilayer, however, has twice the transmission loss at 10 GHz, because the resistivity of W in the alumina multilayer is higher than the Cu in the glass/ceramic multilayer. Crosstalk between striplines in the glass/ceramics is less than -80 dB up to 11 GHz and 9 GHz for alumina

  7. Alumina Extraction from a Pennsylvania Diaspore Clay by an Ammonium Sulfate Process

    Science.gov (United States)

    Fetterman, J. W.; Sun, Shou-Chuan

    A method is proposed for the extraction of alumina from the minerals diaspore, kaolinite and boehmite, the major alumina usinerais in Pennsylvania diaspore clay. The conditions required for optimum alumina extraction and minimum ammonium sulfate loss as determined for the alumina minerals are applied to a naturally occurring diaspore clay. The proposed flowsheet thus obtained is examined in its parts and such variables as particle size, ammonium sulfate to alumina mole ratio, roasting temperature, roasting time, heating rate, leaching cohditions, and purification methods are discussed.

  8. Studying alumina boundary migration using combined microscopy techniques

    International Nuclear Information System (INIS)

    Riesterer, J L; Farrer, J K; Munoz, N E; Gilliss, S R; Ravishankar, N; Carter, C B

    2006-01-01

    Thermal grooving and migration of grain boundaries in alumina have been investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al 2 O 3 was hot-pressed via liquid phase sintering (LPS) to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100-nm thick glass films. Specimens were annealed in air at 1650 deg. C for 20 h to induce boundary migration. Boundary characterization was carried out using visible light (VLM) and scanning electron (SEM) microscopies. Effects on migration due to surface orientation of grains were investigated using electron backscatter diffraction (EBSD). The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650 deg. C for 30 min. The same region of the sample was mapped using VLM and atomic force microscopy (AFM) and followed over a series of 30 min heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest

  9. Studying alumina boundary migration using combined microscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Riesterer, J L [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States); Farrer, J K [Now at Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States); Munoz, N E [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States); Gilliss, S R [Now at Robins, Kaplan, Miller and Ciresi, L.L.P., Minneapolis, MN 55402 (United States); Ravishankar, N [Now at Materials Research Centre, Indian Institute of Science, Bangalore, 560 012 (India); Carter, C B [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States)

    2006-02-22

    Thermal grooving and migration of grain boundaries in alumina have been investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al{sub 2}O{sub 3} was hot-pressed via liquid phase sintering (LPS) to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100-nm thick glass films. Specimens were annealed in air at 1650 deg. C for 20 h to induce boundary migration. Boundary characterization was carried out using visible light (VLM) and scanning electron (SEM) microscopies. Effects on migration due to surface orientation of grains were investigated using electron backscatter diffraction (EBSD). The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650 deg. C for 30 min. The same region of the sample was mapped using VLM and atomic force microscopy (AFM) and followed over a series of 30 min heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest.

  10. Exchange of alkanes with deuterium over γ-alumina

    International Nuclear Information System (INIS)

    John, C.S.; Kemball, C.; Pearce, E.A.; Pearman, A.J.

    1979-01-01

    Exchange reactions of hydrocarbons with deuterium over γ-alumina have been extensively studied but less attention has been directed to the effect of catalyst activation temperature. It has been shown that activity for propane/D 2 exchange passes through a sharp maximum at approximately 823 K and similar behaviour has been shown for the various exchange processes of propene. In this work, the first objective was to examine the effect of varying catalyst activation temperature, Tsub(a), on the subsequent activity of γ-alumina for the exchange of cyclopentane with D 2 ; the effect of chloriding the alumina was also studied. The second objective was to study the influence on the activity for cyclopentane/D 2 exchange of pretreating the catalyst with alkene at various temperatures to determine whether poisoning occurred. The literature indicates that for alkene exchange with deuterium on alumina reaction occurs preferentially for the vinyl hydrogen atoms as opposed to the hydrogen atoms attached to saturated carbon atoms. On this evidence one might expect the presence of alkene to interfere with the exchange of alkanes and indeed there is work which reports that alkene poisons both CH 4 /D 2 and H 2 /D 2 exchange. Finally, the effect of chain-length on the relative rates of methylene and methyl exchange in straight-chain hydrocarbons was examined to follow up previous work on propane and butane. The results are presented and discussed. (author)

  11. Macroporous silica–alumina composites with mesoporous walls

    Indian Academy of Sciences (India)

    Macroporous silica–alumina composites with mesopores have been prepared by employing polymethylmethacrylate beads as templates in the presence of the cationic surfactant, N-cetyl-N,N,N-trimethylammonium bromide. The Si/Al ratio in the composites has been varied between 4.5 and 48 and the occurrence of ...

  12. Grafting of alumina on SBA-15: Effect of surface roughness

    Czech Academy of Sciences Publication Activity Database

    Zukal, Arnošt; Šiklová, Helena; Čejka, Jiří

    2008-01-01

    Roč. 24, č. 17 (2008), s. 9837-9842 ISSN 0743-7463 R&D Projects: GA AV ČR KAN100400701 Institutional research plan: CEZ:AV0Z40400503 Keywords : alumina-grafted materials * SBA-15 * Nitrogen adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.097, year: 2008

  13. Controlled growth of single nanowires within a supported alumina template

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.

    2006-01-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire...

  14. Macroporous silica–alumina composites with mesoporous walls

    Indian Academy of Sciences (India)

    Unknown

    surfactant N-cetyl-N,N,N-trimethylammonium bromide. (CTAB). We describe the macroporous–mesoporous silica– alumina composites with satisfactory/high surface areas. 2. Experimental. Polymethylmethacrylate (PMMA) spheres of diameter. 275 nm were obtained from Soken Chemicals, Japan. These were taken as 1% ...

  15. Encapsulation of proteins into tunable and giant mesocage alumina.

    Science.gov (United States)

    El-Safty, Sherif A; Shenashen, Mohamed A; Ismael, Moahmed; Khairy, Mohamed

    2012-07-07

    Protein bioadsorption has rapidly attracted attention partially because of the promising advances in diagnostic assays, sensors, separations, and gene technology. Tunable and giant mesocage alumina cavities (5 nm to 20 nm) show capability in size-selective encapsulation and diffusivity of large proteins into interior pores.

  16. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    1CSIR–Central Glass & Ceramic Research Institute, Kolkata 700032, India. 2Department of Chemistry, National ... knee implants, etc.), since the coefficient of friction (COF) of diamond is lower than alumina. In this tribological ... Adhesion, friction and wear are the main factors of tribology of contacting or sliding interfaces.

  17. Indentation fatigue in silicon nitride, alumina and silicon carbide ...

    Indian Academy of Sciences (India)

    Unknown

    ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 µm and. 25 µm, and a sintered silicon ... the sintered silicon carbide was found out to be linked to its previous thermal history. Keywords. Indentation fatigue .... This presence of a grain size effect in the RIF behaviour of the ...

  18. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    In view of potential applications in neutron-sensitive ion chambers used in reactor control instru- mentation, studies were carried out on alumina 100 μ to 500 μ thick coatings on copper, aluminium and SS components. The electrical insulation varied from 10 ohms to 10. 骄 ohms for coating thick- nesses above 200 μ.

  19. Effect of alumina coating and extrusion deformation on ...

    Indian Academy of Sciences (India)

    2018-02-05

    Feb 5, 2018 ... (a) TGA–DSC curves of as-received SCF, SCF preform and alumina-coated SCF preforms and (b) XRD .... In order to determine the presence of the reaction product, the composites were fur- ther examined by XRD with a much lower scan speed of. 0.25. ◦ min .... than being parallel to the observing plane.

  20. Alumina and Zirconia Based Layered Composites:Part 1 Preparation

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Maca, K.; Chlup, Zdeněk

    2009-01-01

    Roč. 412, - (2009), s. 221-226 ISSN 1013-9826 R&D Projects: GA ČR(CZ) GA106/06/0724 Institutional research plan: CEZ:AV0Z20410507 Keywords : electrophoretic deposition * alumina * zirconia Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  1. Effect of chemical composition and alumina content on structure and ...

    Indian Academy of Sciences (India)

    Abstract. In the present work, six electrical porcelain compositions with different amount of alumina and silica have been prepared and fired in an industrial furnace at 1300 ◦C. Density, porosity, bending strength and electrical strength were measured in the samples. In order to find a relationship between properties and ...

  2. Formation of complex anodic films on porous alumina matrices

    Indian Academy of Sciences (India)

    The kinetics of growth of complex anodic alumina films was investigated. These films were formed by filling porous oxide films (matrices) having deep pores. The porous films (matrices) were obtained voltastatically in (COOH)2 aqueous solution under various voltages. The filling was done by re-anodization in an electrolyte ...

  3. Plasma Processes: Plasma sprayed alumina coatings for radiation ...

    Indian Academy of Sciences (India)

    Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our Research ...

  4. Indentation fatigue in silicon nitride, alumina and silicon carbide ...

    Indian Academy of Sciences (India)

    Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 m and 25 m, and a sintered silicon carbide (SSiC) are reported. The RIF experiments were conducted using a Vicker's ...

  5. Microwave-assisted brazing of alumina ceramics for electron tube ...

    Indian Academy of Sciences (India)

    2, April 2016, pp. 587–591. c Indian Academy of Sciences. Microwave-assisted brazing of alumina ceramics for electron tube applications. MAYUR SHUKLA1,2 ... 1Academy of Scientific and Innovative Research (AcSIR), CSIR—-Central Glass and Ceramic Research Institute, ... element is the most popular method [2].

  6. Plasmonic properties of gold-coated nanoporous anodic alumina ...

    Indian Academy of Sciences (India)

    Abstract. Anodization of aluminium surfaces containing linearly oriented scratches leads to the formation of nanoporous anodic alumina (NAA) with the nanopores arranged preferentially along the scratch marks. NAA, when coated with a thin gold film, support plasmonic resonances. Dark-field spectroscopy revealed that ...

  7. State of the art: alumina ceramics for energy applications

    International Nuclear Information System (INIS)

    Hauth, W.E.; Stoddard, S.D.

    1978-01-01

    Prominent ceramic raw materials and products manufacturers were surveyed to determine the state of the art for alumina ceramic fabrication. This survey emphasized current capabilities and limitations for fabrication of large, high-density, high-purity, complex shapes. Some directions are suggested for future needs and development

  8. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    Abstract. Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our ...

  9. Optimization of nanocrystalline γ-alumina coating for direct spray ...

    Indian Academy of Sciences (India)

    7, December 2014, pp. 1583–1588. c Indian Academy of Sciences. Optimization of nanocrystalline γ-alumina coating for direct spray water-cooling of optical devices. S N ALAM1,2,∗. , M ANARAKY3, Z SHAFEIZADEH3 and P J PARBROOK1. 1Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, ...

  10. Synthesis of Gamma-Alumina from Kankara Kaolin as Potential ...

    African Journals Online (AJOL)

    In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment ...

  11. Multifunctional substrates of thin porous alumina for cell biosensors

    KAUST Repository

    Toccafondi, Chiara

    2014-02-27

    We have fabricated anodic porous alumina from thin films (100/500 nm) of aluminium deposited on technological substrates of silicon/glass, and investigated the feasibility of this material as a surface for the development of analytical biosensors aiming to assess the status of living cells. To this goal, porous alumina surfaces with fixed pitch and variable pore size were analyzed for various functionalities. Gold coated (about 25 nm) alumina revealed surface enhanced Raman scattering increasing with the decrease in wall thickness, with factor up to values of approximately 104 with respect to the flat gold surface. Bare porous alumina was employed for micro-patterning and observation via fluorescence images of dye molecules, which demonstrated the surface capability for a drug-loading device. NIH-3T3 fibroblast cells were cultured in vitro and examined after 2 days since seeding, and no significant (P > 0.05) differences in their proliferation were observed on porous and non-porous materials. The effect on cell cultures of pore size in the range of 50–130 nm—with pore pitch of about 250 nm—showed no significant differences in cell viability and similar levels in all cases as on a control substrate. Future work will address combination of all above capabilities into a single device.

  12. Obtaining alumina-mullite-zirconia composites using alternative raw materials; Avaliacao microestrural de compositos alumina-mulita-zirconia preparados a partir de bauxita como fonte alternativa de alumina

    Energy Technology Data Exchange (ETDEWEB)

    Nakachima, P.M., E-mail: peter.nakachima@curimbaba.com.br [Mineracao Curimbaba Ltda, Pocos de Caldas, MG (Brazil); Universidade Federal de Sao Carlos (UFSCar), SP (Brazil); Rodrigues, J.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2016-07-01

    Traditionally, ceramic composites of alumina-mullite-zirconia are obtained by the sintering of a mixture of alumina and zircon powders at temperatures above 1570°C. Due to the high purity of these raw materials, the cost of this composite is relatively high and sometimes prohibitive for certain applications. This fact motivated the development of a composite using zircon and bauxite (as an alternative source of alumina). The work herein demonstrates the feasibility of using these raw materials to obtain the desired phases, together with other contaminant phases due to the presence of other oxides in the bauxite, in addition to the SiO{sub 2} and Al{sub 2}O{sub 3}. However, the procedure used was not successful on obtaining the desired amount of ZrO{sub 2}, since the dissociation of the zircon was not complete. Composites were chemically and mineralogically characterized using the X-ray fluorescence and the Rietveld method with X-ray diffraction data, respectively, besides the scanning electron microscopy for the microstructure evaluation. (author)

  13. Performance of adhesives base on PU, Epoxy and silane in the Kevlar/alumina interface; Desempenho de adesivos a base de PU, epoxi e silano na interface Kevlar/alumina

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, K.F.; Melo, F.C.L.; Lopes, C.M.A. [Divisao de Materiais, Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil); Divisao de Engenharia Mecanica-Aeronautica, Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil)], e-mail: cmoniz@iae.cta.br

    2010-07-01

    Hybrid ceramic/polymer composites are used for ballistic protection due to the good high-velocity impact absorption properties. The choice of the proper adhesive used to bond ceramic and polymer layers is one of the major issues for hybrid armor development due to its influence in the ballistic resistance behaviour. This work presents an adhesion study in composites of aramid textile (Kevlar) and alumina. Adhesives of different chemical nature, based on polyurethane, epoxy and silane were evaluated. T-Peel test was performed for the interface characterization and the post- failure surfaces were examined by optical microscopy. In all samples the failure occurred at the interface. The silane-based adhesive showed no interaction with the polymer, while the PU hot melt adhesive presented the highest adhesion strengths. (author)

  14. Application of various types of alumina and nano--alumina sulfuric acid in the synthesis of α-aminonitriles derivatives: comparative study

    Directory of Open Access Journals (Sweden)

    A. Teimouri

    2014-09-01

    Full Text Available An efficient and green protocol for the synthesis of α-aminonitrile derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanide has been developed using natural alumina, alumina sulfuric acid (ASA, nano-g-alumina, nano-g-alumina sulfuric acid (nano-g-ASA under microwave irradiation and solvent-free conditions. The advantages of methods are short reaction times, high yields, milder conditions and easy work up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. DOI: http://dx.doi.org/10.4314/bcse.v28i3.13

  15. Nanostructural characterization of large-scale porous alumina fabricated via anodizing in arsenic acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Akiya, Shunta; Kikuchi, Tatsuya, E-mail: kiku@eng.hokudai.ac.jp; Natsui, Shungo; Suzuki, Ryosuke O.

    2017-05-01

    Highlights: • Anodic porous alumina was formed in an arsenic acid solution. • Potential difference (voltage) anodizing at 340 V was achieved. • The porous alumina was slightly ordered under the appropriate conditions. • Pore sealing behavior was not observed in boiling distilled water. • The porous alumina exhibits a white photoluminescence emission under UV irradiation. - Abstract: Anodizing of aluminum in an arsenic acid solution is reported for the fabrication of anodic porous alumina. The highest potential difference (voltage) without oxide burning increased as the temperature and the concentration of the arsenic acid solution decreased, and a high anodizing potential difference of 340 V was achieved. An ordered porous alumina with several tens of cells was formed in 0.1–0.5 M arsenic acid solutions at 310–340 V for 20 h. However, the regularity of the porous alumina was not improved via anodizing for 72 h. No pore sealing behavior of the porous alumina was observed upon immersion in boiling distilled water, and it may be due to the formation of an insoluble complex on the oxide surface. The porous alumina consisted of two different layers: a hexagonal alumina layer that contained arsenic from the electrolyte and a pure alumina honeycomb skeleton. The porous alumina exhibited a white photoluminescence emission at approximately 515 nm under UV irradiation at 254 nm.

  16. Effects of Processing Temperatures of Nickel Plating on Capacitance Density of Alumina Film Capacitor.

    Science.gov (United States)

    Jeong, Myung-Sun; Ju, Byeong-Kwon; Lee, Jeon-Kook

    2015-06-01

    We observed the effects of nickel plating temperatures for controlling the surface morphologies of the deposited nickel layers on the alumina nano-pores. The alumina nano-channels were filled with nickel at various processing temperatures of 60-90 degrees C. The electrical properties of the alumina film capacitors were changed with processing temperatures. The electroless nickel plating (ENP) at 60 degrees C improved the nickel penetration into the alumina nano-channels due to the reduced reaction rate. Nickel layers are uniformly formed on the high aspect ratio alumina pores. Due to the uniform nickel electrode, the capacitance density of the alumina film capacitors is improved by the low leakage current, dissipation factor and equivalent series resistance. Alumina film capacitors made by ENP at 60 degrees C had a high capacitance density of 160 nF/cm2.

  17. Synthesis and structural evaluation of freeze-cast porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Douglas F., E-mail: souzadf@outlook.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nunes, Eduardo H.M., E-mail: eduardohmn@gmail.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Pimenta, Daiana S.; Vasconcelos, Daniela C.L. [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nascimento, Jailton F.; Grava, Wilson [Petrobras/CENPES, Avenida Horácio Macedo 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ CEP:21941-915 (Brazil); Houmard, Manuel [Department of Materials Engineering and Civil Construction, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 1, sala 3304 (Brazil); Vasconcelos, Wander L., E-mail: wlv@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil)

    2014-10-15

    In this work we fabricated alumina samples by the freeze-casting technique using tert-butanol as the solvent. The prepared materials were examined by scanning electron microscopy and X-ray microtomography. Next, they were coated with sol–gel silica films by dip-coating. Permeability tests were carried out in order to assess the permeation behavior of the materials processed in this study. We observed that the sintering time and alumina loading showed a remarkable effect on both the structural properties and flexural strength of the freeze-cast samples. Nitrogen adsorption tests revealed that the silica prepared in this study exhibited a microporous structure. It was observed that the presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance by about one order of magnitude. Because of the similar kinetic diameters of nitrogen and carbon dioxide, the CO{sub 2}/N{sub 2} system showed a separation efficiency that was lower than that observed for the He/CO{sub 2} and He/N{sub 2} systems. We noticed that increasing the feed pressure improved the separation capacity of the obtained materials. - Highlights: • Porous alumina samples obtained by the freeze-casting technique • Microporous silica coating prepared by a simple sol–gel dip-coating methodology • Samples examined by SEM, μ-CT, and nitrogen sorption tests • Mechanical tests were carried out in the freeze-cast samples. • The presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance.

  18. Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina)

    International Nuclear Information System (INIS)

    Rouquerol, J.

    1964-11-01

    This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina α-trihydrate Al(OH) 3 and beryllium α-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author) [fr

  19. EFFECTIVE ELASTIC PROPERTIES OF ALUMINA-ZIRCONIA COMPOSITE CERAMICS - PART 4. TENSILE MODULUS OF POROUS ALUMINA AND ZIRCONIA

    Directory of Open Access Journals (Sweden)

    W. Pabst

    2004-12-01

    Full Text Available In this fourth paper of a series on the effective elastic properties of alumina-zirconia composite ceramics the influence of porosity on the effective tensile modulus of alumina and zirconia ceramics is discussed. The examples investigated are alumina and zirconia ceramics prepared from submicron powders by starch consolidation casting using two different types of starch, potato starch (median size D50 =47.2 µm and corn starch (median size D50 =13.7 µm. The dependence of effective tensile moduli E, on the porosity f, measured for porosities in the ranges of approx. 19-55 vol.% and 10-42 vol.% for alumina and zirconia, respectively, using a resonant frequency technique, was evaluated by fitting with various model relations, including newly developed ones. A detailed comparison of the fitting results suggests the superiority of the new relation E/E0 = (1 - f·(1 - f/fC, developed by the authors (with the tensile modulus of the dense ceramic material E0 and the critical porosity fC, over most other existing fit models. Only for special purposes and well-behaved data sets the recently proposed exponential relation E/E0 = exp [-Bf/(1 - f] and the well-known Phani-Niyogi relation E/E0 = (1 - f/fCN might be preferable.

  20. Characterization of metallized alumina: properties. [Diamonite P-3142-1, Wesgo Al-500 alumina ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Swearengen, J.C.; Burchett, O.L., Gieske, J.H.

    1976-12-01

    The effects of metallizing and brazing on the mechanical properties of Diamonite P-3142-1 and Wesgo A1-500 alumina ceramics were evaluated. The information was required for analytical prediction of the performance of ceramic-to-metal joints formed by the metallize-braze process. Residual stresses and fracture strengths were monitored before and after metallizing treatments; micromechanical modelling and surface acoustic wave experiments were utilized to determine density, thermal expansion and elastic moduli within the metallized region of the ceramics. It was observed that the metallizing elements penetrate the ceramics to a depth of about 005 ..mu..m and measurably modify the properties to a depth of about 300 ..mu..m. The moduli and density are increased approximately five percent within the penetration zone. The thermal expansion coefficients are not modified significantly by metallizing; the warping which occurs during metallizing results from microstructural changes within the ceramics and not differential thermal contraction. Fracture toughness of the Diamonite ceramic is greater than that of the Wesgo, although the metallizing treatments increase the toughness of each. Fracture strength of the Diamonite was degraded on the metallized surface, whereas the strength of the Wesgo was essentially unchanged by metallizing. Macroscopic compressive residual stresses, which exist at the surfaces of the ceramics, do not significantly affect the fracture strengths. The implications of these results for calculations of joint performance are discussed.

  1. Structural reliability of alumina-, feldspar-, leucite-, mica- and zirconia-based ceramics.

    Science.gov (United States)

    Tinschert, J; Zwez, D; Marx, R; Anusavice, K J

    2000-09-01

    The objective of this study was to test the hypothesis that industrially manufactured ceramic materials, such as Cerec Mark II and Zirconia-TZP, have a smaller range of fracture strength variation and therefore greater structural reliability than laboratory-processed dental ceramic materials. Thirty bar specimens per material were prepared and tested. The four-point bend test was used to determine the flexure strength of all ceramic materials. The fracture stress values were analyzed by Weibull analysis to determine the Weibull modulus values (m) and the 1 and 5% probabilities of failure. The mean strength and standard deviation values for these ceramics are as follows: (MPa+/-SD) were: Cerec Mark II, 86.3+/-4.3; Dicor, 70.3+/-12.2; In-Ceram Alumina, 429. 3+/-87.2; IPS Empress, 83.9+/-11.3; Vitadur Alpha Core, 131.0+/-9.5; Vitadur Alpha Dentin, 60.7+/-6.8; Vita VMK 68, 82.7+/-10.0; and Zirconia-TZP, 913.0+/-50.2. There was no statistically significant difference among the flexure strength of Cerec Mark II, Dicor, IPS Empress, Vitadur Alpha Dentin, and Vita VMK 68 ceramics (p>0.05). The highest Weibull moduli were associated with Cerec Mark II and Zirconia-TZP ceramics (23.6 and 18.4). Dicor glass-ceramic and In-Ceram Alumina had the lowest m values (5.5 and 5.7), whereas intermediate values were observed for IPS-Empress, Vita VMK 68, Vitadur Alpha Dentin and Vitadur Alpha Core ceramics (8.6, 8.9, 10.0 and 13.0, respectively). Except for In-Ceram Alumina, Vitadur Alpha and Zirconia-TZP core ceramics, most of the investigated ceramic materials fabricated under the condition of a dental laboratory were not stronger or more structurally reliable than Vita VMK 68 veneering porcelain. Only Cerec Mark II and Zirconia-TZP specimens, which were prepared from an industrially optimized ceramic material, exhibited m values greater than 18. Hence, we conclude that industrially prepared ceramics are more structurally reliable materials for dental applications although CAD

  2. Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants.

    Science.gov (United States)

    Flamant, Quentin; Caravaca, Carlos; Meille, Sylvain; Gremillard, Laurent; Chevalier, Jérôme; Biotteau-Deheuvels, Katia; Kuntz, Meinhard; Chandrawati, Rona; Herrmann, Inge K; Spicer, Christopher D; Stevens, Molly M; Anglada, Marc

    2016-12-01

    Due to their outstanding mechanical properties and excellent biocompatibility, zirconia-toughened alumina (ZTA) ceramics have become the gold standard in orthopedics for the fabrication of ceramic bearing components over the last decade. However, ZTA is bioinert, which hampers its implantation in direct contact with bone. Furthermore, periprosthetic joint infections are now the leading cause of failure for joint arthroplasty prostheses. To address both issues, an improved surface design is required: a controlled micro- and nano-roughness can promote osseointegration and limit bacterial adhesion whereas surface porosity allows loading and delivery of antibacterial compounds. In this work, we developed an integrated strategy aiming to provide both osseointegrative and antibacterial properties to ZTA surfaces. The micro-topography was controlled by injection molding. Meanwhile a novel process involving the selective dissolution of zirconia (selective etching) was used to produce nano-roughness and interconnected nanoporosity. Potential utilization of the porosity for loading and delivery of antibiotic molecules was demonstrated, and the impact of selective etching on mechanical properties and hydrothermal stability was shown to be limited. The combination of injection molding and selective etching thus appears promising for fabricating a new generation of ZTA components implantable in direct contact with bone. Zirconia-toughened alumina (ZTA) is the current gold standard for the fabrication of orthopedic ceramic components. In the present work, we propose an innovative strategy to provide both osseointegrative and antibacterial properties to ZTA surfaces: we demonstrate that injection molding allows a flexible design of surface micro-topography and can be combined with selective etching, a novel process that induces nano-roughness and surface interconnected porosity without the need for coating, avoiding reliability issues. These surface modifications have the

  3. Testicular failure

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000395.htm Testicular failure To use the sharing features on this page, ... Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also ...

  4. Effect of Cements at Different Temperatures on the Clinical Performance and Marginal Adaptation of Inlay-Onlay Restorations In Vivo.

    Science.gov (United States)

    Aygün Emiroğlu, Şeyda; Evren, Buket; Kulak Özkan, Yasemin

    2016-06-01

    To evaluate the clinical performance of inlays and onlays luted with two different resin cements, mixed at different temperatures and to evaluate the marginal adaptation of the restorations. One hundred IPS e.max restorations (82 onlays, 18 inlays; 84 molars, 16 premolars) were placed in 50 patients (28 females, 22 males, mean age, 33 years). The restorations were assigned to six groups according to the luting agent temperature (25°C, 37°C, and 54°C) and cement type (Variolink N high viscosity or G-Cem Automix). All restorations were evaluated after 1 week and 1 year by two examiners using modified USPHS criteria. Replicas of 30 selected onlay restorations (5 per group) were assessed for marginal quality under a scanning electron microscope (SEM) at 200×. Marginal adaptation was quantitatively evaluated in terms of percentage of gap formation, and marginal gap width was measured. After 1 year, the total survival rates of the Variolink N high viscosity group and G-Cem Automix group were 100% and 93.8%, respectively. Three debondings occurred with the G-Cem Automix group, one from each temperature group. For 1-year clinical service time, no significant difference was noticed in the marginal adaptation of Variolink N high viscosity groups and the 37°C G-Cem Automix group, while 25°C and 54°C G-Cem Automix groups' marginal adaptation scores decreased (p 0.05). Cements at different temperatures did not have significant effects on marginal gap widths of the restorations. The restorations cemented with Variolink N high viscosity cement mixed at the three tested temperatures exhibited better treatment options than the self-adhesive groups. Preheating the self-adhesive cement (G-Cem Automix) to 37°C can be an effective method to have better marginal adaptation than the other self-adhesive groups (25°C, 54°C) tested in this study. © 2015 by the American College of Prosthodontists.

  5. Marginal adaptation of inlay-retained adhesive fixed partial dentures after mechanical and thermal stress: an in vitro study.

    Science.gov (United States)

    Göehring, T N; Peters, O A; Lutz, F

    2001-07-01

    There are no studies that analyze the long-term durability of minimally invasive fixed partial dentures (FPDs) by comparing different methods of adhesive bonding. This in vitro study examined the influence of cavity design and operative technique on the marginal adaptation of resin-bonded composite FPDs. Slot-inlay tooth preparations with cavity margins located in enamel were prepared in 18 maxillary canines and 18 maxillary first molars designated as abutments. The specimens were divided equally into 3 experimental groups. In all groups, butt joint tooth preparations were created in canines and molars. In group 2, canines were prepared additionally with a 1.5-mm wide palatal bevel in enamel. After pretests with modification spaces of 11 and 17 mm (length), 2 missing premolars were replaced by the ceromer Targis and reinforced with the glass-fiber material Vectris. The prostheses were inserted with Tetric Ceram with use of an ultrasonic-supported, high-viscosity technique. Restorations were selectively bonded to cavity finish lines in groups 1 and 2 ("selective bonding"). In group 3, restorations were bonded totally to the whole cavity surface ("total bonding"). The restorations were stressed in a computer-controlled masticator. Marginal quality was examined with an SEM at x 200. The percent area of optimal margins after thermomechanical loading between composite and enamel in each group was as follows: group 1, 86.2% +/- 12.3% for canines and 95.5% +/- 3.5% for molars; group 2, 95.3% +/- 2.1% for canines and 96.2% +/- 2.7% for molars; and group 3, 95% +/- 0.9% for canines and 86.4% +/- 3.2% for molars. The marginal quality for molars inserted with total bonding was significantly lower (P< or =.05). Within the limitations of this study, the selective bonding technique for slot inlay-retained fixed partial dentures resulted in a negligible loss of marginal quality after extensive mechanical and thermal stress. The selective bonding technique is recommended for box

  6. Study of preparation and surface morphology of self-ordered nanoporous alumina; Estudo da preparacao e da morfologia de superficie de alumina nanoporosa auto-organizada

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Elisa Marchezini; Martins, Maximiliano Delany, E-mail: elisamarch@gmail.com, E-mail: MG.mdm@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG. (Brazil); Silva, Ronald Arreguy, E-mail: arregsilva@yahoo.com.br [Centro Universitario de Belo Horizonte (UniBH), Belo Horizonte, MG (Brazil)

    2013-07-01

    Nanoporous alumina is a typical material that exhibits self-ordered nanochannels spontaneously organized in hexagonal shape. Produced by anodizing of metallic aluminum, it has been used as a template for production of materials at the nanoscale. This work aimed to study the preparation of nanoporous alumina by anodic anodizing of metallic aluminum substrates. The nanoporous alumina was prepared following the methodology proposed by Masuda and Fukuda (1995), a two-step method consisting of anodizing the aluminum sample in the potentiostatic mode, removing the layer of aluminum oxide (alumina) formed and then repeat the anodization process under the same conditions as the first anodization. This method produces nanoporous alumina with narrow pore diameter distribution and well-ordered structure. (author)

  7. Ultrasonic characterization of zirconia-toughened alumina ceramics

    International Nuclear Information System (INIS)

    Phani, K.K.; Mukherjee, S.; Basu, D.

    1996-01-01

    Ultrasonic pulse-echo technique was used for the characterization of sintered zirconia-toughened alumina (ZTA) ceramics. The variation of the ultrasonic velocity and elastic constants with the volume fraction of zirconia in the alumina matrix was studied. The ultrasonic velocity variation in these materials also was modeled using a mean-value approach. The zirconia grains in ZTA were modeled by oblate spheroids, whose aspect ratio was estimated from the two-dimensional microstructure of the material using stereological relations. The aspect ratio was then used as a parameter to estimate the ultrasonic velocity variation in the material using self-consistent spheroidal inclusion theory, and the model was validated by comparing the estimated data with the measured velocity values, which showed very good agreement

  8. Controlled fabrication of patterned lateral porous alumina membranes

    International Nuclear Information System (INIS)

    Gowtham, M; Eude, L; Cojocaru, C S; Marquardt, B; Jeong, H J; Legagneux, P; Song, K K; Pribat, D

    2008-01-01

    Confined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation

  9. Glass properties in the yttria-alumina-silica system

    Science.gov (United States)

    Hyatt, M. J.; Day, D. E.

    1987-01-01

    The glass formation region in the yttria-alumina-silica system was investigated. Properties of glasses containing 25 to 55 wt pct yttria were measured and the effect of the composition was determined. The density, refractive index, thermal-expansion coefficient, and microhardness increased with increasing yttria content. The dissolution rate in 1N HCl increased with increasing yttria content and temperature. These glasses were also found to have high electrical resistivity.

  10. Porous Alumina and Zirconia Ceramics With Tailored Thermal Conductivity

    Czech Academy of Sciences Publication Activity Database

    Gregorová, E.; Pabst, W.; Sofer, Z.; Jankovský, O.; Matějíček, Jiří

    2012-01-01

    Roč. 395, č. 1 (2012), 012022-012022 ISSN 1742-6588. [European Thermal Sciences Conference (Eurotherm)/6./. Poitiers, 04.09.2012-07.09.2012] Institutional support: RVO:61389021 Keywords : Ceramics * alumina * zirconia * porosity * thermal conductivity * pore-forming agent * oxide ceramics * starch * porosity Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://iopscience.iop.org/1742-6596/395/1/012022/pdf/1742-6596_395_1_012022.pdf

  11. Ion irradiation effect of alumina and its luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Yasushi; Yamamoto, Shunya; Naramoto, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; My, N.T.

    1997-03-01

    The luminescence spectra of single crystalline alpha-alumina and ruby which has 0.02% of Cr{sub 2}O{sub 3} as a impurity, induced by 200 keV He{sup +} and Ar{sup +} irradiation were measured at room temperature as a function of irradiation dose. The analysis of the measured spectra showed the existence of three main luminescence features in the wavelength region of 250 to 350 nm, namely anionic color centers, F-center at 411 nm and F{sup +}-center at 330 nm and a band observed around 315 nm. As alpha-alumina was irradiated with He{sup +}, F-center and F{sup +}-center luminescence grew and decayed, but the behaviors of those were different from each other. It seems that a concentration quenching occurred on the F-center luminescence in the dose range above 1x10{sup 14} He/cm{sup 2}. Furthermore, F-center luminescence was strongly suppressed in ruby, compared with that in alumina. On the other hand, the luminescence band around 315 nm appeared only in the early stage of irradiation and did not show its growth part. The dose dependent behavior was similar to that of Cr{sup 3+} emission at 695 nm (R-line) in ruby in both cases of He{sup +} and Ar{sup +} irradiation. Based on the experimental results mentioned above, the processes of defect formation and excitation in alumina in the early stage of ion irradiation will be discussed. (author)

  12. Efective infrared reflectivity and dielectric function of polycrystalline alumina ceramics

    Czech Academy of Sciences Publication Activity Database

    Nuzhnyy, Dmitry; Petzelt, Jan; Borodavka, Fedir; Vaněk, Přemysl; Šimek, Daniel; Trunec, D.; Maca, K.

    2017-01-01

    Roč. 254, č. 5 (2017), s. 1-8, č. článku 1600607. ISSN 0370-1972 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : alumina * ceramics * effective dielectric function * effective medium approximation * geometrical resonances * infrared reflectivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.674, year: 2016

  13. Organized Mesoporous Alumina: Synthesis, Structure and Potential in Catalysis

    Czech Academy of Sciences Publication Activity Database

    Čejka, Jiří

    2003-01-01

    Roč. 254, - (2003), s. 327-338 ISSN 0926-860X R&D Projects: GA AV ČR IAA4040001; GA ČR GA104/02/0571; GA MŠk ME 404 Institutional research plan: CEZ:AV0Z4040901 Keywords : organized mesoporous alumina * mesoporous molecular sieves * synthesis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.825, year: 2003

  14. Results of recent KROTOS FCI tests. Alumina vs. corium melts

    Energy Technology Data Exchange (ETDEWEB)

    Huhtiniemi, I.; Magallon, D.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    Recent results from KROTOS fuel-coolant interaction experiments are discussed. Five tests with alumina were performed under highly subcooled conditions, all of these tests resulted in spontaneous steam explosions. Additionally, four tests were performed at low subcooling to confirm, on one hand, the suppression of spontaneous steam explosions under such conditions and, on the other hand, that such a system is still triggerable using an external initiator. The other test parameters in these alumina tests included the melt superheat and the initial pressure. All the tests in the investigated superheat range (150 K - 750 K) produced a steam explosion and no evidence of the explosion suppression by the elevated initial pressure (in the limited range of 0.1 - 0.375 MPa) was observed in the alumina tests. The corium test series include a test with 3 kg of melt under both subcooled and near saturated conditions at ambient pressure. Two additional tests were performed with subcooled water; one test was performed at an elevated pressure of 0.2 MPa with 2.4 kg of melt and another test with 5.1 kg of melt at ambient pressure. None of these tests with corium produced a propagating energetic steam explosion. However, propagating low energy (about twice the energy of the trigger pulse) events were observed. All corium tests produced significantly higher water level swells during the mixing phase than the corresponding alumina tests. Present experimental evidence suggests that the water depletion in the mixing zone suppresses energetic steam explosions with corium melts at ambient pressure and in the present pour geometry. Processes that could produce such a difference in void generation are discussed. (author)

  15. Development of Internal Stresses in Alumina-Zirconia Laminates

    Czech Academy of Sciences Publication Activity Database

    Chlup, Zdeněk; Hadraba, Hynek; Drdlík, D.; Maca, K.; Dlouhý, Ivo

    2012-01-01

    Roč. 507, č. 1 (2012), s. 221-226 ISSN 1013-9826. [International Conference on Electrophoretic Deposition: Fundamentals and Applications /4./. Puerto Vallarta, 02.10.2011-27.10.2011] R&D Projects: GA ČR(CZ) GAP108/11/1644 Institutional research plan: CEZ:AV0Z20410507 Keywords : Alumina * Zirconia * Residual stresses Subject RIV: JL - Materials Fatigue, Friction Mechanics http://www.scientific.net/KEM.507

  16. Advances in Zirconia Toughened Alumina Biomaterials for Total Joint Replacement

    Science.gov (United States)

    Kurtz, Steven M.; Kocagöz, Sevi; Arnholt, Christina; Huet, Roland; Ueno, Masaru; Walter, William L.

    2014-01-01

    The objective of this article is to provide an up-to-date overview of zirconia-toughened alumina (ZTA) components used in total hip arthroplasties. The structure, mechanical properties, and available data regarding the clinical performance of ZTA are summarized. The advancements that have been made in understanding the in vivo performance of ZTA are investigated. This article concludes with a discussion of gaps in the literature related to ceramic biomaterials and avenues for future research. PMID:23746930

  17. MeV ion beam polishing of anodically grown alumina

    International Nuclear Information System (INIS)

    Daudin, B.; Martin, P.

    1988-01-01

    When bombarded with 1 MeV N + ions, the surface of anodically grown alumina films is smoothened. This polishing effect was studied as a function of the ion bombardment fluence and of the substrate temperature in the range 80 - 650 K. The techniques used to characterize the surface roughness were Rutherford Backscattering Spectrometry, Scanning Electron Microscopy and small angle X-rays diffusion. It is suggested that atomic and/or electronic sputtering is responsible for the smoothing effect which was observed

  18. Dependence of the Stabilization of -Alumina on the Spray Process

    Czech Academy of Sciences Publication Activity Database

    Stahr, C.Ch.; Saaro, S.; Berger, L.-M.; Herrmann, M.; Dubský, Jiří; Neufuss, Karel

    2007-01-01

    Roč. 16, 5-6 (2007), s. 822-830 ISSN 1059-9630 R&D Projects: GA ČR(CZ) GA106/05/0483 Institutional research plan: CEZ:AV0Z20430508 Keywords : -Al2O3 stabilization * alumina * chromia * solid solution * X-ray diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.204, year: 2007

  19. Proton adsorption onto alumina: extension of multisite complexation (MUSIC) theory

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, K.; Blum, F.D.

    1999-09-01

    The adsorption isotherm of protons onto a commercial {gamma}-alumina sample was determined in aqueous nitric acid with sodium nitrate as a background electrolyte. Three discrete regions could be discerned in the log-log plots of the proton isotherm determined at the solution pH 5 to 2. The multisite complexation (MUSIC) model was modified to analyze the simultaneous adsorption of protons onto various kinds of surface species.

  20. Vitrification of high-level alumina nuclear waste

    International Nuclear Information System (INIS)

    Brotzman, J.R.

    1979-01-01

    Borophosphate glass compositions have been developed for the vitrification of a high-alumina calcined defense waste. The effect of substituting SiO 2 , P 2 O 5 and CuO for B 2 O 3 on the viscosity and leach resistance was measured. The effect of the alkali to borate ratio and the Li 2 O:Na 2 O ratio on the melt viscosity and leach resistance was also measured

  1. Fractography of Alumina Fibre Reinforced Ex-polysiloxane Matrix Composites

    Czech Academy of Sciences Publication Activity Database

    Rudnayová, E.; Glogar, Petr

    2002-01-01

    Roč. 223, - (2002), s. 119-124 ISSN 1013-9826. [Fractography of Advanced Ceramic s 2001. Stará Lesná, 13.05.2001-16.05.2001] R&D Projects: GA ČR GA104/00/1140; GA ČR GA106/99/0096 Institutional research plan: CEZ:AV0Z3046908 Keywords : alumina fibre * fibrous composite * fracture features Subject RIV: JI - Composite Materials Impact factor: 0.497, year: 2002

  2. Residual stress profiles in veneering ceramic on Y-TZP, alumina and ZTA frameworks: measurement by hole-drilling.

    Science.gov (United States)

    Fukushima, K A; Sadoun, M J; Cesar, P F; Mainjot, A K

    2014-02-01

    The residual stress profile developed within the veneering ceramic during the manufacturing process is an important predicting factor in chipping failures, which constitute a well-known problem with yttria-tetragonal-zirconia polycrystal (Y-TZP) based restorations. The objectives of this study are to measure and to compare the residual stress profile in the veneering ceramic layered on three different polycrystalline ceramic framework materials: Y-TZP, alumina polycrystal (AL) and zirconia toughened alumina (ZTA). The stress profile was measured with the hole-drilling method in bilayered disk samples of 19 mm diameter with a 0.7 mm thick Y-TZP, AL or ZTA framework and a 1.5mm thick layer of the corresponding veneering ceramic. The AL samples exhibited increasing compressive stresses with depth, while compressive stresses switching into interior tensile stresses were measured in Y-TZP samples. ZTA samples exhibited compressive stress at the ceramic surface, decreasing with depth up to 0.6mm from the surface, and then becoming compressive again near the framework. Y-TZP samples exhibited a less favorable stress profile than those of AL and ZTA samples. Results support the hypothesis of the occurrence of structural changes within the Y-TZP surface in contact with the veneering ceramic to explain the presence of tensile stresses. Even if the presence of Y-TZP in the alumina matrix seems to negatively affect the residual stress profiles in ZTA samples in comparison with AL samples, the registered profiles remain positive in terms of veneer fracture resistance. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. γ-radiolysis of methane adsorbed on γ-alumina

    International Nuclear Information System (INIS)

    Norfolk, D.J.; Swan, T.

    1978-01-01

    An earlier study showed that γ-alumina surfaces outgassed above 570 K contain sites involving exposed lattice ions at which methane is chemisorbed during γ-irradiation. When the species so formed are heated they decompose yielding C 1 , C 2 and C 3 alkanes and alkanes together with hydrogen. The present study investigates the kinetics of the reactions occurring during irradiation. These reactions are shown to be the activation of surface sites and the dissociative chemisorption of methane, in accord with the mechanism previously suggested. Overall product yields are chiefly determined by the rate at which excited charge carriers reach the surface, the highest rate observed being G(- CH 4 ) = 2.0 but declining when fewer than approximately 3 x 10 15 m -2 chemisorption sites remain unoccupied. A kinetic scheme is proposed to account for the variation in yields with methane coverage, radiation dose and dose rate, and specific surface area of the γ-alumina. It is also shown that the individual products formed when the precursors decompose depend on the configuration of the methane chemisorption sites, and so on the origin of the γ-alumina and the outgassing temperature used. Two subsidiary reactions are identified. The first of these resembles normal radiolysis but occurs at sites less accessible to methane. In the second, however, new surface species are formed when irradiation continues after either the methane or the chemisorption sites have been exhausted. These scavenge part of the adsorbed hydrocarbon material. (author)

  4. Dielectric properties of alumina/zirconia composites at millimeter wavelengths

    International Nuclear Information System (INIS)

    Molla, J.; Heidinger, R.; Ibarra, A.; Link, G.

    1994-01-01

    Alumina-zirconia composites with ZrO 2 contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO 2 is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO 2 , t-ZrO 2 ). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al 2 O 3 , 14-21 for m-ZrO 2 and 40-45 for t-ZrO 2 . The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO 2 ; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO 2 , which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO 2 strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO 2 is avoided

  5. Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

    Directory of Open Access Journals (Sweden)

    Morteza Aramesh

    2015-08-01

    Full Text Available A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general.

  6. Investigation of vapor explosions with alumina droplets in sodium

    International Nuclear Information System (INIS)

    Zimmer, H.J.

    1991-02-01

    Within the analysis of severe hypothetical fast breeder accidents the consequence of a fuel-coolant interaction has to be considered i.e. the thermal interaction between hot molten fuel and sodium. Experiments have been performed to study the thermal fragmentation of a molten alumina droplet in sodium. Alumina temperatures up to 3100 K and sodium temperatures up to 1143 K were used. For the first time film boiling of alumina drops in sodium was achieved. With some droplets undergoing film boiling, the fragmentation was triggered by an externally applied pressure wave. The trigger was followed promptly by a strong reaction pressure wave if and only if a contact temperature threshold of T I =2060±160 K was exceeded. In agreement with similar experiments in which other materials were studied this threshold corresponds to an interfacial temperature close to the homogeneous nucleation temperature of the vaporising liquid. Based on the present and previous experimental results a model concept of thermal fragmentation is developed. (orig.) [de

  7. Physical Properties of Copper Based MMC Strengthened with Alumina

    Directory of Open Access Journals (Sweden)

    Kaczmar J. W.

    2014-06-01

    Full Text Available The aim of this work is the development of Cu-Al2O3 composites of copper Cu-ETP matrix composite materials reinforced by 20 and 30 vol.% Al2O3 particles and study of some chosen physical properties. Squeeze casting technique of porous compacts with liquid copper was applied at the pressure of 110 MPa. Introduction of alumina particles into copper matrix affected on the significant increase of hardness and in the case of Cu-30 vol. % of alumina particles to 128 HBW. Electrical resistivity was strongly affected by the ceramic alumina particles and addition of 20 vol. % of particles caused diminishing of electrical conductivity to 20 S/m (34.5% IACS. Thermal conductivity tests were performed applying two methods and it was ascertained that this parameter strongly depends on the ceramic particles content, diminishing it to 100 Wm-1K-1 for the composite material containing 30 vol.% of ceramic particles comparing to 400 Wm-1K-1 for the unreinforced copper. Microstructural analysis was carried out using SEM microscopy and indicates that Al2O3 particles are homogeneously distributed in the copper matrix. EDS analysis shows remains of silicon on the surface of ceramic particles after binding agent used during preparation of ceramic preforms.

  8. Electrochemical impedance spectroscopy characterization of nanoporous alumina dengue virus biosensor.

    Science.gov (United States)

    Nguyen, Binh Thi Thanh; Peh, Alister En Kai; Chee, Celine Yue Ling; Fink, Katja; Chow, Vincent T K; Ng, Mary M L; Toh, Chee-Seng

    2012-12-01

    The Faradaic electrochemical impedance technique is employed to characterize the impedance change of a nanoporous alumina biosensor in response towards the specific binding of dengue serotype 2 (Denv2) viral particles to its serotype 2-specific immunoglobulin G antibody within the thin alumina layer. The optimal equivalent circuit model that matches the impedimetric responses of the sensor describes three distinct regions: the electrolyte solution (R(s)), the porous alumina channels (including biomaterials) (Q(1), R(1)) and the conductive electrode substrate layer (Q(2), R(2)). Both channel resistance R(1) and capacitance Q(1) change in response to the increase of the Denv2 virus concentration. A linear relationship between R(1) and Denv2 concentration from 1 to 900 plaque forming unit per mL (pfu mL(-1)) can be derived using Langmuir-Freundlich isotherm model. At 1pfu mL(-1) Denv2 concentration, R(1) can be distinguished from that of the cell culture control sample. Moreover, Q(1) doubles when Denv2 is added but remains unchanged in the presence of two other non-specific viruses - West Nile virus and Chikungunya virus indicates biosensor specificity can be quantitatively measured using channel capacitance. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. A Study on the Effect of Nano Alumina Particles on Fracture Behavior of PMMA

    Directory of Open Access Journals (Sweden)

    Arezou Sezavar

    2015-04-01

    Full Text Available In the current research, the role of nano-sized alumina on deformation and fracture mechanism of Poly Methyl Methacrylate (PMMA was investigated. For this purpose, PMMA matrix nanocomposite reinforced with different wt% of alumina (i.e., 5, 10 and 15 were fabricated using the compression molding technique. Tensile properties of produced nanocomposites were studied using Zwick Z250 apparatus at cross head speed of about 5 mm/min. In order to specify the role of alumina nanoparticles on deformation and fracture mechanism of PMMA, microscopic evaluation was performed using scanning electron microscope (SEM. The achieved results prove that tensile properties of PMMA depend on alumina wt%. For example, addition of 15 wt% alumina to PMMA causes an increase of about 25% modulus of elasticity. Micrographs taken from the fracture surface of PMMA and its nanocomposites show deformation and fracture mechanism of PMMA changes as alumina is added to it.

  10. The role of surface preparation in corrosion protection of copper with nanometer-thick ALD alumina coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mirhashemihaghighi, Shadi; Światowska, Jolanta [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Maurice, Vincent, E-mail: vincent.maurice@chimie-paristech.fr [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Seyeux, Antoine; Klein, Lorena H. [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Salmi, Emma; Ritala, Mikko [Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Marcus, Philippe [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France)

    2016-11-30

    Highlights: • 10–50 nm thick alumina coatings were grown on copper by atomic layer deposition. • Surface smoothening by substrate annealing was studied as pre-deposition treatment. • Corrosion protection is promoted by pre-treatment for 10 nm but not for thicker films. • Local adhesion failure is assigned to the stresses accumulated in the thicker films. • Surface smoothening decreases the interfacial strength bearing the film stresses. - Abstract: Surface smoothening by substrate annealing was studied as a pre-treatment for improving the corrosion protection provided to copper by 10, 20 and 50 nm thick alumina coatings deposited by atomic layer deposition. The interplay between substrate surface state and deposited film thickness for controlling the corrosion protection provided by ultrathin barrier films is demonstrated. Pre-annealing at 750 °C heals out the dispersed surface heterogeneities left by electropolishing and reduces the surface roughness to less than 2 nm independently of the deposited film thickness. For 10 nm coatings, substrate surface smoothening promotes the corrosion resistance. However, for 20 and 50 nm coatings, it is detrimental to the corrosion protection due to local detachment of the deposited films. The weaker adherence of the thicker coatings is assigned to the stresses accumulated in the films with increasing deposited thickness. Healing out the local heterogeneities on the substrate surface diminishes the interfacial strength that is bearing the stresses of the deposited films, thereby increasing adhesion failure for the thicker films. Pitting corrosion occurs at the local sites of adhesion failure. Intergranular corrosion occurs at the initially well coated substrate grain boundaries because of the growth of a more defective and permeable coating at grain boundaries.

  11. Comparative study on sintered alumina for ballistic shielding application; Estudo comparativo entre aluminas sinterizadas visando aplicacao em blindagem balistica

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Francisco Cristovao Lourenco de; Goncalves, Diniz Pereira [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. de Aeronautica e Espaco

    1997-12-31

    This work presents a development of the armor made from special ceramic materials and kevlar. An experimental investigation was conducted to study the ballistic penetration resistance on three samples taken from sintered alumina: a commercial one and two formulations A and B made in IAE/CTA. The main differences between the two formulations was the grain size and bend resistance. The knowledge of the mechanisms during the penetration and perforation process allowed to apply a ductile composite laminate made form kevlar under the alumina to delay its rupture. The last ballistic test showed how a Weibull`s modulii and other mechanical properties are able to improve ballistic penetration resistance. (author) 3 refs.

  12. Heterogeneous burnable poisons. Sinterability study in oxidizing atmosphere of alumina-gadolinia and alumina-boron carbide compounds

    International Nuclear Information System (INIS)

    Agueda, H.C.; Leiva, S.F.; Russo, D.O.

    1990-01-01

    Solid burnable poisons are used in reactors cooled by pressure light water (PLWR) with the purpose of controlling initial reactivity in the first reactor's core. The burnable poisons may be uniformly mixed with the fuel -known as 'homogeneous' poisons-; or constituting separate elements -known as heterogeneous poisons-. The purpose of this work is to present the results of two sinterability studies, performed on Al 2 O 3 -Gd 2 O 3 and Al 2 O 3 -B 4 C, where alumina acts as inert matrix, storing the absorbing elements as Gd 2 O 3 or B 4 C. The elements were sintered at an air atmosphere and additives permitting the obtention of a greater density alumina were tested at lower temperatures than the characteristic for this material, in order to determine its compatibility with the materials dealt with herein. (Author) [es

  13. Produksi Biogasoline Dari Minyak Sawit Melalui Reaksi Perengkahan Katalitik Dengan Katalis γ-Alumina

    OpenAIRE

    Anondho Wijanarko; Dadi Ahmad Mawardi; Mohammad Nasikin

    2006-01-01

    Biogasoline Production from Palm Oil Via Catalytic Hydrocracking over Gamma-Alumina Catalyst. Bio gasolineconversion from palm oil is an alternative energy resources method which can be substituted fossil fuel base energyutilization. Previous research resulted that palm oil can be converted into hydrocarbon by catalytic cracking reactionwith γ-alumina catalyst. In this research, catalytic cracking reaction of palm oil by γ-alumina catalyst is done in a stirrerbatch reactor with th...

  14. Improved alumina sol FCC catalysts meet challenges of the 1990s

    International Nuclear Information System (INIS)

    Alkemade, V.; Cartlidge, S.; Thompson, J.M.

    1990-01-01

    This paper discusses how improved alumina sol, fluid catalytic cracking (FCC) catalysts allow refiners to upgrade heavier feeds containing high amounts of vanadium and nickel to give premium octane gasolines. When an alumina sol binder is used in catalyst preparation, the desired nickel and vanadium-tolerant alumina phase is formed by precise control of the catalyst finishing conditions. New zeolite formulas also increase gasoline motor octane number and lower gasoline octane sensitivity maintaining gasoline yields

  15. Contraceptive failure

    DEFF Research Database (Denmark)

    Rasch, Vibeke

    2002-01-01

    , and 2614 received antenatal care. The variables studied comprise age, partner relationship, number of births, occupational and economical situation, and contraceptive use.Contraceptive failure, defined as contraceptive use (condom, diaphragm, IUD, oral contraception, or another modern method...... to use of condom and oral contraception than women aged 25-34 years. In addition, contraceptive failure was found to be associated with being single, a student, and having given birth twice or more previously. Regarding pregnancy acceptance, being 25-34 years of age was positively associated, whereas...

  16. INFLUENCE OF POST-CURE TREATMENTS ON HARDNESS AND MARGINAL ADAPTATION OF COMPOSITE RESIN INLAY RESTORATIONS: AN IN VITRO STUDY

    Science.gov (United States)

    Poskus, Laiza Tatiana; Latempa, Antonio Marcelo Accetta; Chagas, Maurício Alves; da Silva, Eduardo Moreira; Leal, Mariana Pareira da Silva; Guimarães, José Guilherme Antunes

    2009-01-01

    Objectives: The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments. Material and Methods: For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130°C); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5% was adopted for all analyses. Results: The post-cure treatments increased the hardness of conventional composites (pinlay restorations (pinlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values. PMID:20027437

  17. Removal of Arsenic from Drinking Water Using Modified Activated Alumina

    Directory of Open Access Journals (Sweden)

    Mohammad Mosaferi

    2005-09-01

    Full Text Available Considering contamination of drinking water to arsenic in some villages ofIran. In order to develop a simple method for household water treatment in rural areas, efficiency of  modified activated alumina with iron compounds- a product of Alcan Company with trade name of AAFS-50- was studied Equilibrium batch experiments were carried out using shaker incubator and arsenic was analyzed with SDDC method. Effects of initial concentration of arsenic, adsorbent dose, oxidation state of arsenic, pH and oxidation with chlorine on adsorption were studied. Correlation coefficient of Freundlich and Laungmuier  isotherms  for As(V and As(III were 0.964 , 0.991 and 0.970, 0.978 respectively . These results show that adsorption of arsenic on modified activated alumina is compatible with both models specially Laungmuier models. Removal efficiency of As(V at 0.5 ,1 and 2 hr increased with doubling the adsorbent dose from 44.8 to 72%, 69.6 to 90.8 and 92.4 to 98% ; respectively. Experiments using different concentrations of arsenic showed that adsorption of arsenic on activated alumina are a first order reaction that is, rate of reaction is dependent on intial; concentration of arsenic. Removal efficiency for concentration of 0.250 mg/L of arsenic, with increasing of reaction time from 15 min to 60 min, increased 1.54 times and reached from 61% to 94%. During 2hrs, removal of As(V and As(III were 96% and 16% respectively. Using 1.5 mg/L Chlorine as oxidant agent, removal of As(III was increased to 94%. In the case of pH effect, rate of adsorption increased for arsenite, with increasing of pH to 8 and decreased with more increasing, so that adsorption at pH 14 was equal to pH 2. For arsenate, the most adsorption was observed at pH between 6 to 8 . These results show that by using the studied activated alumina, there will not be need for adjustment of pH and the activated alumina used in this study could have application as a safe adsorbent for removal of

  18. The Effect of Novel Synthetic Methods and Parameters Control on Morphology of Nano-alumina Particles

    Science.gov (United States)

    Xie, Yadian; Kocaefe, Duygu; Kocaefe, Yasar; Cheng, Johnathan; Liu, Wei

    2016-05-01

    Alumina is an inorganic material, which is widely used in ceramics, catalysts, catalyst supports, ion exchange and other fields. The micromorphology of alumina determines its application in high tech and value-added industry and its development prospects. This paper gives an overview of the liquid phase synthetic method of alumina preparation, combined with the mechanism of its action. The present work focuses on the effects of various factors such as concentration, temperature, pH, additives, reaction system and methods of calcination on the morphology of alumina during its preparation.

  19. The statistical average of optical properties for alumina particle cluster in aircraft plume

    Science.gov (United States)

    Li, Jingying; Bai, Lu; Wu, Zhensen; Guo, Lixin

    2018-04-01

    We establish a model for lognormal distribution of monomer radius and number of alumina particle clusters in plume. According to the Multi-Sphere T Matrix (MSTM) theory, we provide a method for finding the statistical average of optical properties for alumina particle clusters in plume, analyze the effect of different distributions and different detection wavelengths on the statistical average of optical properties for alumina particle cluster, and compare the statistical average optical properties under the alumina particle cluster model established in this study and those under three simplified alumina particle models. The calculation results show that the monomer number of alumina particle cluster and its size distribution have a considerable effect on its statistical average optical properties. The statistical average of optical properties for alumina particle cluster at common detection wavelengths exhibit obvious differences, whose differences have a great effect on modeling IR and UV radiation properties of plume. Compared with the three simplified models, the alumina particle cluster model herein features both higher extinction and scattering efficiencies. Therefore, we may find that an accurate description of the scattering properties of alumina particles in aircraft plume is of great significance in the study of plume radiation properties.

  20. Determination of calcium and magnesium in nuclear grade alumina by ion chromatography technique

    International Nuclear Information System (INIS)

    Hespanhol, E.C.B.; Pires, M.A.F.; Atalla, L.T.

    1987-07-01

    A simple method for solubilization of alumina and separation of magnesium and calcium from alumina matrix was developed by initial coprecipitation of those elements with iron(III) hydroxide. Calcium and magnesium were later separated from iron chloride anionic complex in a Dowex 1-X 10 anionic exchange resin. The ion chromatography tecnnique was employed for the analysis of calcium and magnesium. One hundred percent recovery for calcium and magnesium was obtained in their separation from alumina. A precision of 6% and 10% for magnesium and calcium, respectively, was obtained in alumina samples analysis which contain less than 0,02% of magnesium and less than 0,08% of calcium. (Author) [pt

  1. Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

    International Nuclear Information System (INIS)

    Yusof Abdullah; Abd Fatah Awang Mat; Mohd Ali Sufi; Sarimah Mahat; Razali Kassim; Nurhaslinda Abdullah.

    1996-03-01

    The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

  2. The effect of alumina nanofillers size and shape on mechanical behavior of PMMA matrix composite

    Directory of Open Access Journals (Sweden)

    Ben Hasan Somaya Ahmed

    2014-01-01

    Full Text Available Composites with the addition of alumina nanofillers show improvement in mechanical properties. The PMMA polymer was used as a matrix and two different types of nanofillers, having extremely different shapes were added in the matrix to form the composite. Reinforcements were based on alumina nanoparticles having either spherical shape or whiskers having the length to diameter ratio of 100. The influence of alumina fillers size, shape and fillers loading on mechanical properties of prepared composite were studied using the nanoindentation measurements and dynamic mechanical analysis. It was observed that both alumina whiskers and alumina spherical nanoparticles added in the PMMA matrix improved the mechanical properties of the composite but the improvement was significantly higher with alumina whisker reinforcement. The concentration of the reinforcing alumina spherical nanoparticles and alumina whiskers in PMMA matrix varied up to 5 wt. %. The best performance was obtained by the addition of 3 wt. % of alumina whiskers in the PMMA matrix with regard to mechanical properties of the obtained composite.

  3. Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, Katherine [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The viscosities of both aqueous and cyanate ester monomer (BECy) based suspensions of alumina nanoparticle were studied. The applications for these suspensions are different: aqueous suspensions of alumina nanoparticles are used in the production of technical ceramics made by slip casting or tape casting, and the BECy based suspensions are being developed for use in an injection-type composite repair resin. In the case of aqueous suspensions, it is advantageous to achieve a high solids content with low viscosity in order to produce a high quality product. The addition of a dispersant is useful so that higher solids content suspensions can be used with lower viscosities. For BECy suspensions, the addition of nanoparticles to the BECy resin is expected to enhance the mechanical properties of the cured composite. The addition of saccharides to aqueous suspensions leads to viscosity reduction. Through DSC measurements it was found that the saccharide molecules formed a solution with water and this resulted in lowering the melting temperature of the free water according to classic freezing point depression. Saccharides also lowered the melting temperature of the bound water, but this followed a different rule. The shear thinning and melting behaviors of the suspensions were used to develop a model based on fractal-type agglomeration. It is believed that the structure of the particle flocs in these suspensions changes with the addition of saccharides which leads to the resultant viscosity decrease. The viscosity of the BECy suspensions increased with solids content, and the viscosity increase was greater than predicted by the classical Einstein equation for dilute suspensions. Instead, the Mooney equation fits the viscosity behavior well from 0-20 vol% solids. The viscosity reduction achieved at high particle loadings by the addition of benzoic acid was also investigated by NMR. It appears that the benzoic acid interacts with the surface of the alumina particle which may

  4. Reproductive Failure

    African Journals Online (AJOL)

    The need for the establishment of a Reproductive Failure. Clinic at Groote Schuur Hospital was considered long overdue, as it was felt that there were a number of high risk pregnancies continually being lost among the large volume of pregnant women attending the routine, busy and overcrowded antenatal clinics,. Various ...

  5. Failure Modes

    DEFF Research Database (Denmark)

    Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo

    1999-01-01

    The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained...

  6. Fiber damage during the consolidation of PVD Ti-6Al-4V coated NEXTEL 610 trademark alumina fibers

    International Nuclear Information System (INIS)

    Warren, J.; Elzey, D.M.; Wadley, H.N.G.

    1995-01-01

    Titanium matrix composites reinforced with sol-gel synthesized α-alumina fiber tows have attracted interest as a potentially low cost continuous fiber reinforced metal matrix composite system. The authors have conducted a detailed investigation of fiber damage during high temperature consolidation of PVD Ti-6Al-4V metallized sol-gel alumina fiber tows. Using both hot isostatic pressing and interrupted vacuum hot press consolidation cycles, the two principal mechanisms of fiber damage have been experimentally identified to be microbending/fracture and fiber matrix reaction. A time dependent micromechanics model incorporating the evolving geometry and mechanical properties of both the fibers and matrix has been formulated to simulate the fiber bending/failure mechanism in a representative unit cell and explore the effect of fiber strength loss due to reaction with the matrix. This model has been used to design a process cycle that minimizes damage by exploiting the enhanced superplastic deformation of the initially nanocrystalline PVD Ti-6Al-4V matrix

  7. Kidney (Renal) Failure

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Kidney Failure Kidney failure, also known as renal failure, is ... is kidney failure treated? What is kidney (renal) failure? The kidneys are designed to maintain proper fluid ...

  8. Long-term performance of posterior InCeram Alumina crowns cemented with different luting agents: a prospective, randomized clinical split-mouth study over 5 years.

    Science.gov (United States)

    Selz, Christian F; Strub, Joerg R; Vach, Kirstin; Guess, Petra C

    2014-07-01

    This prospective, randomized clinical split-mouth study investigated the 5-year performance of InCeram Alumina posterior crowns cemented with three different luting cements. 4-META- and MDP-based cements were used for adhesive luting. Glass ionomer cement served as control. Sixty patients were treated with 149 (n = 62 Panavia F/MDP; n = 59 SuperBond-C&B/4-META; n = 28 Ketac Cem/glass ionomer) InCeram Alumina crowns on vital molars and premolars in a comparable position. Follow-up examinations were performed annually up to 5 years after crown placement using the modified United States Public Health Service (USPHS) criteria. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations (cement types showed significant marginal deterioration over time (p crowns showed acceptable long-term survival and success rates independent of luting agent used. Ceramic fractures, endodontical treatments and secondary caries were the most frequent failures. Glass-infiltrated Alumina crowns in combination with adhesive as well as conventional cementation can be considered as a reliable treatment option in posterior teeth.

  9. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: Anin vitrostudy.

    Science.gov (United States)

    Gopalan, Reji P; Nair, Vivek V; Harshakumar, K; Ravichandran, R; Lylajam, S; Viswambaran, Prasanth

    2018-01-01

    Different pattern materials do not produce copings with satisfactory, marginal accuracy when used on stone dies at varying time intervals. The purpose of this study was to evaluate and compare the vertical marginal accuracy of patterns formed from three materials, namely, thermoplastic resin, light cured wax and inlay casting wax at three-time intervals of 1, 12, and 24 h. A master die (zirconia abutment mimicking a prepared permanent maxillary central incisor) and metal sleeve (direct metal laser sintering crown #11) were fabricated. A total of 30 stone dies were obtained from the master die. Ten patterns were made each from the three materials and stored off the die at room temperature. The vertical marginal gaps were measured using digital microscope at 1, 12, and 24 h after reseating with gentle finger pressure. The results revealed a significant statistical difference in the marginal adaptation of three materials at all the three-time intervals. Light cured wax was found to be most accurate at all time intervals, followed by thermoplastic resin and inlay casting wax. Furthermore, there was a significant difference between all pairs of materials. The change in vertical marginal gap from 1 to 24 h between thermoplastic resin and light cured wax was not statistically significant. The marginal adaptation of all the three materials used, was well within the acceptable range of 25-70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

  10. The inlay osteotome sinus augmentation technique for placing short implants simultaneously with reduced crestal bone height. A short-term follow-up.

    Science.gov (United States)

    Teng, Minhua; Liang, Xing; Yuan, Quan; Nie, Jing; Ye, Jun; Cheng, Qian; Zhai, Junjiang; Liao, Jian; Sun, Xu; Wen, Cai; Mo, Anchun

    2013-12-01

    To display an inlay technique of osteotome sinus floor elevation using a trephine combined with simultaneous short implant placement where the residual bone height (RBH) is less than 5 mm, as well as to evaluate the clinical effect in a prospective study. Fifty short implants were installed in 32 patients in the severely atrophic posterior maxilla immediately after sinus floor elevation between January 2010 and October 2012. An inlay osteotome sinus augmentation technique using a trephine was applied in the operation. The mean residual bone height adjacent to or beneath the sinus was 3.34 mm, ranging from 0.96 mm to 4.96 mm. It was rarely necessary to add graft material from bovine sources in this therapy. With the purpose of bite training and soft tissue reforming, the temporary crowns were fixed after 6 months. The final prostheses were restored 3 months later. The stability and osseointegration of the implants were clinically evaluated, also the bone height gain around the implants was measured. The survival rate was 100% during the study period with this procedure. Each of the implants, loaded without pain or any subjective sensation, was clinically stable. No implants had detectable sinus membrane perforation during operation. The radiographic results demonstrated that the bone height gain was 5.38 mm after the surgery. Based on the results and within the limits of the present study, it can be suggested that short implant placement in conjunction with this inlay osteotome sinus augmentation technique could yield predictable clinical results for edentulous posterior maxillary region with RBH less than 5 mm. Besides, from the clinical point of view, these techniques may reduce the indication for complex invasive procedures and simplify treatment in the posterior. © 2013 Wiley Periodicals, Inc.

  11. Cementado de inlays de composite. Estudio in vitro de la aplicación de un imprimador en el cementado de las incrustaciones de resina compuesta

    OpenAIRE

    Macorra García, José Carlos de la

    1992-01-01

    Los problemas de la adhesión de una resina compuesta a una incrustación de resina compuesta cuyo índice de conversión es alto son, entre otros, la baja reactividad de las paredes de la incrustación y la restricción a un mínimo del espacio en el que se aloja el cemento, entre las caras adhesivas dentaria y restauradora. El primer problema puede afrontarse mediante la aplicación de un imprimador que disuelva en parte la matriz de la resina del inlay. En este experimento se prueba uno d...

  12. Failure Analysis

    International Nuclear Information System (INIS)

    Iorio, A.F.; Crespi, J.C.

    1987-01-01

    After ten years of operation at the Atucha I Nuclear Power Station a gear belonging to a pressurized heavy water reactor refuelling machine, failed. The gear box was used to operate the inlet-outlet heavy-water valve of the machine. Visual examination of the gear device showed an absence of lubricant and that several gear teeth were broken at the root. Motion was transmitted with a speed-reducing device with controlled adjustable times in order to produce a proper fitness of the valve closure. The aim of this paper is to discuss the results of the gear failure analysis in order to recommend the proper solution to prevent further failures. (Author)

  13. Failure Assessment

    Science.gov (United States)

    Lutz, Robyn; Nikora, Allen

    2005-01-01

    Three questions to which software developers want accurate, precise answers are "How can the software system fail?", "mat bad things will happen if the software fails?t', and "How many failures will the software experience?". Numerous techniques have been devised to answer these questions; three of the best known are: 1) Software Fault Tree Analysis (SFTA) 2) Software Failure Modes, Effects, and Criticality Analysis (SFMECA 3) Software Fault/Failure Modeling. SFTA and SFMECA have been successfully used to analyze the flight software for a number of robotic planetary exploration missions, including Galileo, Cassini, and Deep Space 1. Given the increasing interest in reusing software components from mission to mission, one of us has developed techniques for reusing the corresponding portions of the SFTA and SFMECA, reducing the effort required to conduct these analyses. SFTA has also been shown to be effective in analyzing the security aspects of software systems; intrusion mechanisms and effects can easily be modeled using these techniques. The Bi- Directional Safety Analysis (BDSA) method combines a forward search (similar to SFMECA) from potential failure modes to their effects, with a backward search (similar to SFTA) from feasible hazards to the contributing causes of each hazard. BDSA offers an efficient way to identify latent failures. Recent work has extended BDSA to product-line applications such as flight-instrumentation displays and developed tool support for the reuse of the failure-analysis artifacts within a product line. BDSA has also been streamlined to support those projects having tight cost and/or schedule constraints for their failure analysis efforts. We discuss lessons learned from practice, describe available tools, and identi@ some future directions for the topic. A substantial amount of research has been devoted to estimating the number of failures that a software system will experience during test and operations, as well as the number of

  14. The effects of reactive elements on the oxidation of alumina-forming iron-chromium-aluminium alloys at high temperature

    International Nuclear Information System (INIS)

    Deakin, J.; Prunier, V.; Wood, G.C.; Stott, F.H.

    1995-01-01

    A study is being undertaken into the influence of sulphur and reactive elements on the growth and adhesion of alumina scales on iron-chromium-base alloys during thermal cycling in air from 1300 C. A low-sulphur- (< 10 ppm) containing alloy has shown considerable improvements in scale adhesion compared with an alloy containing a higher concentration of sulphur. Additions of reactive elements to the low sulphur-containing alloy had little further effect on scale adhesion, although second-phase precipitates facilitated preferential inward growth of the scale and the development of a very irregular scale/alloy interface. All the alloys showed evidence for stress development during scale growth, but this was often relieved by flow of the weak alloy. Although not extensive, all the low sulphur-containing alloys exhibited some scale failure, involving both a decohesion, buckling and tensile cracking route and a shear cracking and wedging route. (orig.)

  15. Method for thermal processing alumina-enriched spinel single crystals

    Science.gov (United States)

    Jantzen, Carol M.

    1995-01-01

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.

  16. The Ammonoalunite Process for Production of Alumina from Clay

    Science.gov (United States)

    Bartlett, Robert W.; Wesely, Rolf J.; Bolles, Thomas R.

    The ammonoalunite process begins with two-stage sulfuric acid leaching of calcined kaolinitic clay. The clarified aluminum sulfate liquor is subjected to modest temperature autoclaving in the presence of ammonium ions to precipitate the ammonium analog of alunite, NH4Al3(SO4)2(OH)6, in a hydrolysis reaction regenerating most of the acid needed in the leach. This acid liquor is recycled while the filtered ammonoalunite is thermally decomposed to alumina. Decomposition gases are scrubbed to recover ammonia and the remaining acid needed for leaching. Experimental results on precipitation parameters, thermal decomposition, energy consumption, and impurity control are given.

  17. Silicon carbide whisker-zirconia reinforced mullite and alumina ceramics

    Science.gov (United States)

    Becher, Paul F.; Tiegs, Terry N.

    1987-01-01

    The flexural strength and/or fracture toughness of SiC whisker-reinforced composites utilizing mullite or alumina as the matrix material for the composite are increased by the addition of zirconia in a monoclinic or tetragonal phase to the matrix. The zirconia addition also provides for a lower hot-pressing temperature and increases the flexural strength and/or fracture toughness of the SiC whisker-reinforced composites over SiC whisker-reinforced composites of the similar matrix materials reinforced with similar concentrations of SiC whiskers.

  18. Processing, nanoindentation and scratch testing of alumina-coated YTZP

    Directory of Open Access Journals (Sweden)

    Jorge Valle

    2015-07-01

    The proposed processing method involves dipping of pre-sintered YTZP specimens in stable alumina suspensions and co-sintering of the dipped specimens. The influence of the processing parameters on the macro and microstructure of the materials has been established. Berkovich indentation has been performed to determine the Young's modulus of the substrates and coatings. The structural integrity of the coatings has been analysed using scratch tests. The Young's modulus. The optimised specimens present high resistance to scratch up to loads of 150 N.

  19. Techniques for detection of transition phases in calcined alumina

    International Nuclear Information System (INIS)

    Pandolfelli, V.C.; Folgueras-Dominguez, S.

    1987-01-01

    Detection of transition phases in alumina, is very important in the receiving control and calcination of aluminium hydroxide. The non alfa or transition phases difficults the processability and causes localized shrinkage on sintering compromising the dimensional and mechanical aspects of the product. In this research using refraction index, absorption of dyes, specific density, X-ray diffraction and scanning electron microscopy, analyses, are done in calcined hydroxides submited to different thermal treatments. The limits and facilities of each technique are discussed and compared. (Author) [pt

  20. Recovery of alumina and some heavy metals from sulfate liquor

    Directory of Open Access Journals (Sweden)

    M.N. El Hazek

    2016-05-01

    Full Text Available The gibbsite bearing shale occurrence in the Paleozoic sedimentary sequence of SW Sinai, Egypt, was found to be associated with several metal values. From sulfate liquor prepared by proper leaching, the recovery of these metal values has been studied. Alumina was first separated in the form of potash alum followed by Cu-selective extraction by hydroxyoxime LIX-973N solvent. Then U recovery using an anionic exchange resin Amberlite IRA-400 was achieved. For the associated heavy metal Zn, it was subsequently extracted using di-2-ethylhexyl phosphoric acid. The relevant factors affecting the extraction process were adequately studied.

  1. Electrochemically replicated smooth aluminum foils for anodic alumina nanochannel arrays

    International Nuclear Information System (INIS)

    Biring, Sajal; Tsai, K-T; Sur, Ujjal Kumar; Wang, Y-L

    2008-01-01

    A fast electrochemical replication technique has been developed to fabricate large-scale ultra-smooth aluminum foils by exploiting readily available large-scale smooth silicon wafers as the masters. Since the adhesion of aluminum on silicon depends on the time of surface pretreatment in water, it is possible to either detach the replicated aluminum from the silicon master without damaging the replicated aluminum and master or integrate the aluminum film to the silicon substrate. Replicated ultra-smooth aluminum foils are used for the growth of both self-organized and lithographically guided long-range ordered arrays of anodic alumina nanochannels without any polishing pretreatment

  2. The Assessment of Alumina Production Waste Impact on Natural Water

    Directory of Open Access Journals (Sweden)

    Vladimir Sergeevich Kuznetsov

    2018-03-01

    Full Text Available The paper is dedicated to the issue of assessment of alumina (red mud production waste on natural water. The growth of the number of aluminium-producing facilities leads to the expansion of exclusion areas to store the production waste – sludge dumps. A considerable part of research on red mud utilisation is focused on its use in the iron-and-steel industry. Furthermore, the technologies of red mud usage in the construction industry gain substantial significance for land reclamation, isolation of polluted industrial and agricultural lands as well as the effluent and industrial emissions treatment.

  3. Effects of Variable Aspect-Ratio Inclusions on the Electrical Impedance of an Alumina Zirconia Composite at Intermediate Temperatures

    Science.gov (United States)

    Goldsby, Jon C.

    2010-01-01

    A series of alumina-yttria-stabilized zirconia composites containing either a high aspect ratio (5 and 30 mol%) hexagonal platelet alumina or an alumina low aspect ratio (5 and 30 mol%) spherical particulate was used to determine the effect of the aspect ratio on the temperature-dependent impedance of the composite material. The highest impedance across the temperature range of 373 to 1073 K is attributed to the grain boundary of the hexagonal platelet second phase in this alumina zirconia composite.

  4. Modification of alumina matrices through chemical etching and electroless deposition of nano-Au array for amperometric sensing

    Directory of Open Access Journals (Sweden)

    Valinčius Gintaras

    2007-01-01

    Full Text Available AbstractSimple nanoporous alumina matrix modification procedure, in which the electrically highly insulating alumina barrier layer at the bottom of the pores is replaced with the conductive layer of the gold beds, was described. This modification makes possible the direct electron exchange between the underlying aluminum support and the redox species encapsulated in the alumina pores, thus, providing the generic platform for the nanoporous alumina sensors (biosensors with the direct amperometric signal readout fabrication.

  5. Sulfuric Acid and Ammonium Sulfate Leaching of Alumina from Lampang Clay

    Directory of Open Access Journals (Sweden)

    Paweena Numluk

    2012-01-01

    Full Text Available The rapid development of the global alumina industry has led to a considerable increase in the production alumina and processing of alumina from non-bauxitic sources. Lampang clays comprise various minerals that contain about 22.70 wt% of extractable alumina. Local clay was ground, activated by calcination and treated with sulfuric acid to extract alumina. In the activation step, the effects of temperature and time on the extraction of alumina and iron were investigated. The leaching experiments were performed on clay samples with particle sizes less than 200 mesh. The samples were calcined at different temperatures, ranging from 450°C to 1050°C, and for different periods, ranging from 30 to 150 min. The optimum conditions for the extraction of alumina from Lampang clay include grinding the clay to pass through a 200 mesh sieve, calcining the ground clay at 750°C for 30 min, extracting the alumina from the calcined clay by leaching with 3M sulfuric acid, and using an acid to clay ratio of 80 wt% at 100°C for 120 min. An aluminum dissolution efficiency of 95.1 % was achieved under the conditions that resulted in the maximum dissolution efficiency of iron (26.6 %.

  6. Measurement of Elastic Modulus of Alumina and Barium Strontium Titanate Wafers Produced by Tape Casting Method

    Science.gov (United States)

    2014-02-01

    DATES COVERED (From – To) 4. TITLE AND SUBTITLE MEASUREMENT OF ELASTIC MODULUS OF ALUMINA AND BARIUM STRONTIUM TITANATE WAFERS PRODUCED BY...configuration testing method. Samples of barium strontium titanate (BST) were made using a regular powder pressing, sintering, pelletizing, and...fabricated using thin wafers of barium strontium titanate (BST) and aluminum oxide (alumina) ceramic during launch of a system. Sandia National

  7. Experimental investigation of nano-alumina effect on the filling time ...

    African Journals Online (AJOL)

    In this research, by producing composite samples made of glass fibers and epoxy resin with different percentages of nanoparticles (Nano-alumina), the adding effect of nanoparticles of alumina Alpha and Gamma grade on filling time in the vacuum assistant resin transfer molding process (VARTM) is investigated. The grade ...

  8. All cause mortality and incidence of cancer in workers in bauxite mines and alumina refineries

    NARCIS (Netherlands)

    Fritschi, Lin; Hoving, Jan Lucas; Sim, Malcolm R.; del Monaco, Anthony; Macfarlane, Ewan; McKenzie, Dean; Benke, Geza; de Klerk, Nicholas

    2008-01-01

    Bauxite is a reddish clay that is refined to produce alumina, which is then reduced to aluminium. There have been studies examining the health of workers in aluminium smelters, but not workers in bauxite mining and alumina refining. A cohort of employees of 1 large aluminium company since 1983 was

  9. Study of aluminium oxide from high-alumina refractory ceramics by ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. This work is focused on the study of the thermally stimulated blue emission of aluminium oxide. (Al2O3) that has been removed from twenty different high alumina-rich refractory bricks. The glow curve sensitivity of several alumina grains are defined by (i) a maximum centred at about 165°C that can be decon-.

  10. Scattering properties of alumina particle clusters with different radius of monomers in aerocraft plume

    Science.gov (United States)

    Li, Jingying; Bai, Lu; Wu, Zhensen; Guo, Lixin; Gong, Yanjun

    2017-11-01

    In this paper, diffusion limited aggregation (DLA) algorithm is improved to generate the alumina particle cluster with different radius of monomers in the plume. Scattering properties of these alumina clusters are solved by the multiple sphere T matrix method (MSTM). The effect of the number and radius of monomers on the scattering properties of clusters of alumina particles is discussed. The scattering properties of two types of alumina particle clusters are compared, one has different radius of monomers that follows lognormal probability distribution, another has the same radius of monomers that equals the mean of lognormal probability distribution. The result show that the scattering phase functions and linear polarization degrees of these two types of alumina particle clusters are of great differences. For the alumina clusters with different radius of monomers, the forward scatterings are bigger and the linear polarization degree has multiple peaks. Moreover, the vary of their scattering properties do not have strong correlative with the change of number of monomers. For larger booster motors, 25-38% of the plume being condensed alumina. The alumina can scatter radiation from other sources present in the plume and effect on radiation transfer characteristics of plume. In addition, the shape, size distribution and refractive index of the particles in the plume are estimated by linear polarization degree. Therefore, accurate scattering properties calculation is very important to decrease the deviation in the related research.

  11. Microstructure-mechanical behaviour relationship in alumina-calcium exaluminate composites; Relaciones microestructura-comportamiento mecanico en materiales de alumina-hexaluminato calcico

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Herencia, A. J.; Moreno, R.; Baudin, C.

    2001-07-01

    The grain growth behaviour of dense alumina materials has been modified by the addition of calcium hexaluminate particles. Maximum dispersion has been obtained by colloidal processing routes. The influence of sintering temperature (1500-1600 degree centigree) on the size and shape of the alumina grains has been established. The mechanical behaviour of three composite materials with the same composition ({approx}10 vol% CA{sub 6}) and large microstructural differences has been studied in comparison with that of monophasic alumina of the same grain size. The influence of grain size and shape on toughness has been established. R-curve behaviour has been detected during fracture of the material with the alumina grains presenting the largest shape factor. (Author) 18 refs.

  12. Modelling of fast jet formation under explosion collision of two-layer alumina/copper tubes

    Directory of Open Access Journals (Sweden)

    I Balagansky

    2017-09-01

    Full Text Available Under explosion collapse of two-layer tubes with an outer layer of high-modulus ceramics and an inner layer of copper, formation of a fast and dense copper jet is plausible. We have performed a numerical simulation of the explosion collapse of a two-layer alumina/copper tube using ANSYS AUTODYN software. The simulation was performed in a 2D-axis symmetry posting on an Eulerian mesh of 3900x1200 cells. The simulation results indicate two separate stages of the tube collapse process: the nonstationary and the stationary stage. At the initial stage, a non-stationary fragmented jet is moving with the velocity of leading elements up to 30 km/s. The collapse velocity of the tube to the symmetry axis is about 2 km/s, and the pressure in the contact zone exceeds 700 GPa. During the stationary stage, a dense jet is forming with the velocity of 20 km/s. Temperature of the dense jet is about 2000 K, jet failure occurs when the value of effective plastic deformation reaches 30.

  13. A pre-anodized inlaying ultrathin carbon paste electrode for simultaneous determination of uric acid and folic acid

    International Nuclear Information System (INIS)

    Huo, Jing’e; Shangguan, Enbo; Li, Quanmin

    2013-01-01

    Graphical abstract: In 0.10 mol/L PBS (pH 6.00), oxidation reaction occurred at the PAIUCPE owing to uric acid (UA) loss electrons, while oxygen dissolved in the feed was reduced at the platinum electrode. Furthermore, the effect of electrode reaction at the platinum electrode on that of working electrode is detailedly discussed. Highlights: ► The simultaneous determination of UA and FA is achieved at the PAIUCPE. ► The effect of reaction at the Pt electrode on that of working electrode is discussed. ► The effect of pH on peak currents is detailedly explained for the first time. -- Abstract: A pre-anodized inlaying ultrathin carbon paste electrode (PAIUCPE) was prepared by electrochemical pretreatment. The scanning electron microscope (SEM) was applied to characterize the surface morphology of PAIUCPE and the performance of the electrode was characterized by cyclic voltammetry (CV). The results indicated that PAIUCPE displayed excellent electrocatalysis for the oxidation of uric acid (UA) and folic acid (FA). The separated extent between the two oxidation peaks of UA and FA was 324 mV, which was enough for the simultaneous detection. In 0.10 mol/L PBS (pH 6.00), the linear scan voltammetry (LSV) response of UA and FA increased linearly with the concentration in the range of 4.0 × 10 −6 –3.5 × 10 −4 mol/L and 3.0 × 10 −6 –2.0 × 10 −4 mol/L with the detection limits of 1.1 × 10 −7 mol/L and 1.5 × 10 −7 mol/L, respectively. It was successfully used to determine UA and FA in human urine simultaneously

  14. High toughness alumina/aluminate: The role of hetero-interfaces

    International Nuclear Information System (INIS)

    Brito, M.E.; Yasuoka, M.; Kanzaki, S.

    1996-01-01

    Silica doped alumina/aluminate materials present a combination of high strength and high toughness not achieved before in other alumina systems, except for transformation toughened alumina. The authors have associated the increase in toughness to crack bridging by anisotropically grown alumina grains with concurrent interfacial debonding of these grains. A HREM study of grain boundaries and hetero-interface structures in this material shows the absence of amorphous phases at grain boundaries. Local Auger electron analysis of fractured surfaces revealed the coexistence of Si and La at the grain facets exposed by the noticeable intergranular fracture mode of this material. It is concluded that a certain and important degree of boundaries weakness is related to both presence of Si at the interfaces and existence of alumina/aluminate hetero-interfaces

  15. Safety Assessment of Alumina and Aluminum Hydroxide as Used in Cosmetics.

    Science.gov (United States)

    Becker, Lillian C; Boyer, Ivan; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2016-11-01

    This is a safety assessment of alumina and aluminum hydroxide as used in cosmetics. Alumina functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent. Aluminum hydroxide functions as a buffering agent, corrosion inhibitor, and pH adjuster. The Food and Drug Administration (FDA) evaluated the safe use of alumina in several medical devices and aluminum hydroxide in over-the-counter drugs, which included a review of human and animal safety data. The Cosmetic Ingredient Review (CIR) Expert Panel considered the FDA evaluations as part of the basis for determining the safety of these ingredients as used in cosmetics. Alumina used in cosmetics is essentially the same as that used in medical devices. This safety assessment does not include metallic or elemental aluminum as a cosmetic ingredient. The CIR Expert Panel concluded that alumina and aluminum hydroxide are safe in the present practices of use and concentration described in this safety assessment. © The Author(s) 2016.

  16. Bauxite mining and alumina refining: process description and occupational health risks.

    Science.gov (United States)

    Donoghue, A Michael; Frisch, Neale; Olney, David

    2014-05-01

    To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Review article. The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures.

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

    NARCIS (Netherlands)

    Valandro, L.F.; Ozcan, M.; Bottino, M.C.; Bottino, M.A.; Scotti, R.; Della Bona, A.

    2006-01-01

    Purpose: 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)

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

    NARCIS (Netherlands)

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

    Purpose: 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)

  19. Heart failure - tests

    Science.gov (United States)

    CHF - tests; Congestive heart failure - tests; Cardiomyopathy - tests; HF - tests ... best test to: Identify which type of heart failure (systolic, diastolic, valvular) Monitor your heart failure and ...

  20. Comparative evaluation of the effect of cavity disinfectants on the fracture resistance of primary molars restored with indirect composite inlays: An in vitro study

    Directory of Open Access Journals (Sweden)

    Indira M

    2010-01-01

    Full Text Available A study was conducted to evaluate and compare the effect of cavity disinfectants on the fracture resistance of primary molars restored with indirect composite inlays. Thirty-six non-carious primary second molars were selected and divided randomly into three groups (n = 12: control group (no disinfectant, chlorhexidine group (disinfected with 2% chlorhexidine for 40 seconds and sodium hypochlorite group crowns (disinfected with 2% chlorhexidine for 40 seconds. The inlays were fabricated by indirect method using Ceram X nanocomposite on plaster die. All the groups were submitted to compression mechanic test in a Hounsfield universal testing machine at 1 mm/min cross-head speed and the results were calculated in Newtons. Descriptive statistics, independent t test, and one way analysis of variance (ANOVA test revealed the mean fracture resistance of three groups, i.e., control group, chlorhexidine group and sodium hypochlorite group to be 2260.66, 1858.08 and 1310.66, respectively. When intragroup comparisons were made, a significant difference was observed in all the groups (P<0.001. Scheffe′s post hoc test revealed that control group had the highest fracture resistance, followed by chlorhexidine group, and sodium hypochlorite group had the least fracture resistance. Each value differed significantly from the other (P<0.05. Cavity disinfectants used in the present study had detrimental effect on the fracture resistance of primary molars. Among the disinfectants employed in the present study, chlorhexidine showed a better resistance to fracture than sodium hypochlorite.

  1. Synthesis of magnesium aluminate spinel by periclase and alumina chlorination

    International Nuclear Information System (INIS)

    Orosco, Pablo; Barbosa, Lucía; Ruiz, María del Carmen

    2014-01-01

    Highlights: • Use of chlorination for the synthesis of magnesium aluminate spinel. • The reagents used were alumina, periclase and chlorine. • Isothermal and non-isothermal assays were performed in air and Cl 2 –N 2 flows. • The chlorination produced magnesium aluminate spinel at 700 °C. • Selectivity of the chlorination reaction to obtain spinel is very high. - Abstract: A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al 2 O 3 (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl 2 atmosphere of the MgO–Al 2 O 3 mixture produces magnesium aluminate spinel at 700 °C, while in air, magnesium spinel is generated at 930 °C. The synthesis reaction of magnesium aluminate spinel was complete at 800 °C

  2. Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A [ORNL; Brady, Michael P [ORNL; Yamamoto, Yukinori [ORNL; Santella, Michael L [ORNL; Maziasz, Philip J [ORNL; Matthews, Wendy [Capstone Turbines

    2011-01-01

    A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900 C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to 100 m thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675 C and 750 C, showing excellent creep strength compared with other candidate foil materials. Laboratory exposures in humid air at 650 800 C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil. DOI: 10.1115/1.4002827

  3. Synthesis of magnesium aluminate spinel by periclase and alumina chlorination

    Energy Technology Data Exchange (ETDEWEB)

    Orosco, Pablo, E-mail: porosco@unsl.edu.ar [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis Chacabuco y Pedernera, San Luis (Argentina); Barbosa, Lucía [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Instituto de Ciencias Básicas (ICB), Universidad Nacional de Cuyo Parque General San Martín, Mendoza (Argentina); Ruiz, María del Carmen [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis Chacabuco y Pedernera, San Luis (Argentina)

    2014-11-15

    Highlights: • Use of chlorination for the synthesis of magnesium aluminate spinel. • The reagents used were alumina, periclase and chlorine. • Isothermal and non-isothermal assays were performed in air and Cl{sub 2}–N{sub 2} flows. • The chlorination produced magnesium aluminate spinel at 700 °C. • Selectivity of the chlorination reaction to obtain spinel is very high. - Abstract: A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al{sub 2}O{sub 3} (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl{sub 2} atmosphere of the MgO–Al{sub 2}O{sub 3} mixture produces magnesium aluminate spinel at 700 °C, while in air, magnesium spinel is generated at 930 °C. The synthesis reaction of magnesium aluminate spinel was complete at 800 °C.

  4. Alumina ceramics prepared with new pore-forming agents

    Directory of Open Access Journals (Sweden)

    Zuzana Živcová

    2008-06-01

    Full Text Available Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed, which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch to approximately 1 mm (poppy seed, all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds and starch consolidation casting (using metal molds are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry.

  5. Synthesis of Alumina Thin Films Using Reactive Magnetron Sputtering Method

    Science.gov (United States)

    Angarita, G.; Palacio, C.; Trujillo, M.; Arroyave, M.

    2017-06-01

    Alumina (Al2O3) thin films were deposited on Si (100) by Magnetron Sputtering in reactive conditions between an aluminium target and oxygen 99.99% pure. The plasma was formed employing Argon with an R.F power of 100 W, the dwelling time was 3 hours. 4 samples were produced with temperatures between 350 and 400 ºC in the substrate by using an oxygen flow of 2 and 8 sccm, the remaining parameters of the process were fixed. The coatings and substrates were characterized using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) in order to compare their properties before and after deposition. The films thicknesses were between 47 and 70 nm. The results show that at high oxygen flow the alumina structure prevails in the coatings while at lower oxygen flow only aluminum is deposited in the coatings. It was shown that the temperature increases grain size and roughness while decreasing the thicknesses of the coatings.

  6. Stability of amorphous silica-alumina in hot liquid water.

    Science.gov (United States)

    Hahn, Maximilian W; Copeland, John R; van Pelt, Adam H; Sievers, Carsten

    2013-12-01

    Herein, the hydrothermal stability of amorphous silica-alumina (ASA) is investigated under conditions relevant for the catalytic conversion of biomass, namely in liquid water at 200 °C. The hydrothermal stability of ASA is much higher than that of pure silica or alumina. Interestingly, the synthetic procedure used plays a major role in its resultant stability: ASA prepared by cogelation (CG) lost its microporous structure, owing to hydrolysis of the siloxane bonds, but the resulting mesoporous material still had a considerable surface area. ASA prepared by deposition precipitation (DP) contained a silicon-rich core and an aluminum-rich shell. In hot liquid water, the latter structure was transformed into a layer of amorphous boehmite, which protected the particle from further hydrolysis. The surface area showed relatively minor changes during the transformation. Independent of the synthetic method used, the ASAs retained a considerable concentration of acid sites. The concentration of acid sites qualitatively followed the changes in surface area, but the changes were less pronounced. The performance of different ASAs for the hydrolysis of cellobiose into glucose is compared. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Inelastic neutron scattering studies of methyl chloride synthesis over alumina.

    Science.gov (United States)

    Lennon, David; Parker, Stewart F

    2014-04-15

    Not only is alumina the most widely used catalyst support material in the world, it is also an important catalyst in its own right. One major chemical process that uses alumina in this respect is the industrial production of methyl chloride. This is a large scale process (650,000 metric tons in 2010 in the United States), and a key feedstock in the production of silicones that are widely used as household sealants. In this Account, we show how, in partnership with conventional spectroscopic and reaction testing methods, inelastic neutron scattering (INS) spectroscopy can provide additional insight into the active sites present on the catalyst, as well as the intermediates present on the catalyst surface. INS spectroscopy is a form of vibrational spectroscopy, where the spectral features are dominated by modes involving hydrogen. Because of this, most materials including alumina are largely transparent to neutrons. Advantageously, in this technique, the entire "mid-infrared", 0-4000 cm(-1), range is accessible; there is no cut-off at ~1400 cm(-1) as in infrared spectroscopy. It is also straightforward to distinguish fundamental modes from overtones and combinations. A key parameter in the catalyst's activity is the surface acidity. In infrared spectroscopy of adsorbed pyridine, the shifts in the ring stretching modes are dependent on the strength of the acid site. However, there is a very limited spectral range available. We discuss how we can observe the low energy ring deformation modes of adsorbed pyridine by INS spectroscopy. These modes can undergo shifts that are as large as those seen with infrared inspectroscopy, potentially enabling finer discrimination between acid sites. Surface hydroxyls play a key role in alumina catalysis, but in infrared spectroscopy, the presence of electrical anharmonicity complicates the interpretation of the O-H stretch region. In addition, the deformations lie below the infrared cut-off. Both of these limitations are irrelevant

  8. Structure transformations in ion implanted anodic alumina films

    International Nuclear Information System (INIS)

    Cherenda, N.N.; Uglov, V.V.; Litvinovich, G.V.; Daniluyk, A.L.

    2002-01-01

    The effect of ion implantation on aluminium oxide has been widely studied. The change of mechanical, electrical, optical and chemical properties were investigated. Most studies were performed on a single crystal (a- or c-oriented) α-Al 2 O 3 though polycrystalline α-Al 2 O 3 or amorphous aluminium oxide films were the subject of the investigation too. Porous anodic alumina films were the object of the investigation of this work. An unique structure, low cost, controllability and ease of production allow it application in developing of microelectronic devices. Earlier it was shown that implantation of metal ions in anodic alumina films decreases its surface resistance to tens of Ωm. The aim of this work was the investigation of anodic alumina films structure changes after implantation. The implantation of Ti and Cu ions was carried out using a MEVVA source with an impulse duration of 1 ms. The applied acceleration voltage was 80 kV, the ions current density - 53 μA/cm 2 , the doses -1·10 17 ions/cm 2 and 1.5·10 18 ions/cm 2 . Implantation was carried out into two types of crystalline structure: amorphous and γ-Al 2 O 3 . The latter structure was produced by annealing at 830 deg. C. A variety of techniques were used for phase and element composition investigations: X-ray diffraction analysis, Auger electron spectroscopy, Rutherford backscattering analysis and scanning electron microscopy. It was found that implantation into amorphous film results in the formation of γ-AO 2 O 3 while implantation into γ-Al 2 O 3 film - in the formation of an amorphous structure. Implantation both to amorphous and crystalline AA films also led to the formation of θ-Al 2 O 3 phase inclusions in the film structure. The whole structure of AA films with the thickness of 200 μm undergoes these transformations. Implantation also lead to sputtering of the surface barrier layer thus resulting in the shift of the ions depth profile to the surface at higher doses. Diffusion of Ti

  9. Uso de incrustaciones de resina compuesta tipo onlay en molares estructuralmente comprometidos Use of onlay-type composite resin inlays in structurally involved molars

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Cruz González

    2012-03-01

    Full Text Available Las incrustaciones en resina compuesta son una alternativa de bajo costo ante los métodos de obturación directos, frente a las dificultades de la adaptación marginal y la ubicación de contactos proximales, porque permiten otorgar una mejor anatomía dental a la restauración y superar el fenómeno de contracción al polimerizar grandes capas de material por fuera de la cavidad dental. El objetivo del presente artículo fue exponer el uso de la resina compuesta bajo técnica indirecta como una alternativa de fácil manipulación y resultados clínicos considerables ante la afectación estructural de molares. Se presentaron dos casos clínicos de incrustaciones con resina compuesta de tipo inlay onlay en dos molares permanentes afectados estructuralmente, uno de ellos fue tratado endodónticamente. Para la obtención de un troquel de trabajo sobre el que se confecciona la incrustación bajo técnica incremental se obtienen modelos al impresionar con alginato la arcada de los dientes seleccionados, se realiza vaciado en silicona liviana del diente preparado y el resto en yeso piedra tipo III. El proceso de cementación en la cavidad bucal se lleva a cabo con cemento resinoso de doble curado. Las incrustaciones fueron sometidas a un control a los seis meses para evaluar los signos de filtración o desadaptación marginal mediante el secado con aire de la jeringa triple, explorador y radiografías periapicales, que mostraron ausencia de desadaptación o pigmentación marginal. Se concluyó que ante la afectación estructural de molares, las incrustaciones con resina compuesta bajo técnica indirecta fueron de fácil manipulación y se obtuvieron satisfactorios resultados clínicos.The composite resin inlays are a low cost alternative which seeks improvements to the direct filling methods meet the challenges of the marginal adaptation, location of proximal contacts, allows us to improve the restoration dental anatomy and overcome the phenomenon of

  10. Acute kidney failure

    Science.gov (United States)

    Kidney failure; Renal failure; Renal failure - acute; ARF; Kidney injury - acute ... Symptoms of acute kidney failure may include any of the following: Bloody stools Breath odor and metallic taste in the mouth Bruising easily Changes in ...

  11. Types of Heart Failure

    Science.gov (United States)

    ... Venous Thromboembolism Aortic Aneurysm More Types of Heart Failure Updated:May 8,2017 Left-sided heart failure ... This content was last reviewed May 2017. Heart Failure • Home • About Heart Failure Introduction Types of Heart ...

  12. Cement Thickness of Inlay Restorations Made of Lithium Disilicate, Polymer-Infiltrated Ceramic and Nano-Ceramic CAD/CAM Materials Evaluated Using 3D X-Ray Micro-Computed Tomography.

    Science.gov (United States)

    Uzgur, Recep; Ercan, Ertuğrul; Uzgur, Zeynep; Çolak, Hakan; Yalçın, Muhammet; Özcan, Mutlu

    2016-08-12

    To evaluate the marginal and internal cement thicknesses of inlay restorations made of various CAD/CAM materials using 3D X-ray micro-computed tomography (micro-CT) technique. Caries-free extracted mandibular molars (N = 30) with similar size were randomly assigned to three groups (N = 10 per group). Mesio-occlusal-distal (MOD) cavities were prepared, and inlay restorations were obtained by milling out CAD/CAM materials namely, (a) IPS: monolithic lithium disilicate (control), (b) VE: polymer-infiltrated ceramic, and (c) CS: nano-ceramic using a CAM unit. Marginal and internal cement thicknesses were measured using 3D micro-CT. Data were analyzed using 1-way ANOVA and Tukey's tests (alpha = 0.05). The mean marginal and internal cement thickness were not significant in all inlay materials (p > 0.05). Mean marginal cement thickness (μm) was the lowest for the IPS group (67.54 ± 10.16) followed by VE (84.09 ± 3.94) and CS (95.18 ± 10.58) (p > 0.05). The internal cement thickness (μm) was the lowest in the CS group (54.85 ± 6.94) followed by IPS (60.58 ± 9.22) and VE (77.53 ± 12.13) (p > 0.05). Marginal and internal cement thicknesses of MOD inlays made of monolithic lithium disilicate, polymer-infiltrated ceramic, and nano-ceramic CAD/CAM materials were similar and all less than 100 μm, which could be considered clinically acceptable. MOD inlays made of different CAD/CAM materials presented similar cement thickness, less than 100 μm. © 2016 by the American College of Prosthodontists.

  13. Wet chemical synthesis of nickel supported on alumina catalysts; Sintese de catalisadores de niquel suportado em alumina por via umida

    Energy Technology Data Exchange (ETDEWEB)

    Freire, Ranny Rodrigues; Costa, Talita Kenya Oliveira; Morais, Ana Carla da Fonseca Ferreira; Costa, Ana Cristina Figueiredo de Melo; Freitas, Normanda Lino de, E-mail: normanda@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2016-07-01

    Heterogenic catalysts are those found to be in a different phase on the reaction when compared to the reactants and products. Preferred when compared to homogeneous catalysts due to the easiness on which the separation is processed. The objective of this study is to obtain and characterize Alumina based catalysts impregnated with Nickel (Al{sub 2}O{sub 3}), by wet impregnation. The alumina was synthesized by combustion reaction. Before and after the impregnation the catalysts were characterized by X-ray diffraction (XRD), granulometric analysis, the textural analysis will be held by nitrogen adsorption (BET), energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The results show a presence of a stable crystalline phase of Al2O3 in all the studied samples and after the impregnation the second phase formed was of NiO and NiAl{sub 2}O{sub 4}. The Al{sub 2}O{sub 3} e Ni/Al{sub 2}O{sub 3} catalysts resulted in clusters with a medium diameter of 18.9 and 14.2 μm, respectively. The catalysts show a medium-pore characteristic (medium pore diameter between 2 and 50 nm), the superficial area to Al{sub 2}O{sub 3} and Ni/Al{sub 2}O{sub 3} catalysts were 8.69 m{sup 2}/g and 5.56 m{sup 2}/g, respectively. (author)

  14. Microstructural changes in copper-graphite-alumina nanocomposites produced by mechanical alloying.

    Science.gov (United States)

    Rodrigues, Ivan; Guedes, Mafalda; Ferro, Alberto C

    2015-02-01

    Microstructural features of nanostructured copper-matrix composites produced via high-energy milling were studied. Copper-graphite-alumina batches were planetary ball milled up to 16 h; copper-graphite batches were also prepared under the same conditions to evaluate the effect of contamination from the milling media. The microstructure of the produced materials was characterized by field emission gun scanning electron microscopy/energy-dispersive spectroscopy and related to Raman, X-ray diffraction, and particle size analysis results. Results showed that alumina was present in all milled powders. However, size reduction was effective at shorter times in the copper-graphite-alumina system. In both cases the produced powders were nanostructured, containing graphite and alumina nanoparticles homogeneously distributed in the copper matrix, especially for longer milling times and in the presence of added alumina. Copper crystallite size was significantly affected above 4 h milling; nanographite size decreased and incipient amorphization occurred. A minimum size of 15 nm was obtained for the copper crystallite copper-alumina-graphite composite powders, corresponding to 16 h of milling. Contamination from the media became more significant above 8 h. Results suggest that efficient dispersion and bonding of graphite and alumina nanoparticles in the copper matrix is achieved, envisioning high conductivity, high strength, and thermal stability.

  15. STUDY ON ADSORPTION OF Cd(II BY CHITOSAN-ALUMINA

    Directory of Open Access Journals (Sweden)

    Darjito Darjito

    2010-06-01

    Full Text Available One techniques to reduce the concentration of heavy metal Cd(II in aqueous solution is adsorption by chitosan. To modify the surface textures and expose the active binding sites, composite biosorbent has been prepared by coating chitosan onto alumina. The aims of this research were to identify the functional group of chitosan-alumina, to characterize adsorption of Cd(II by using chitosan-alumina adsorbent including optimum pH, optimum agitation time, and to determine the adsorption capacity of the adsorbent. The functional group of chitosan-alumina was identified by infrared spectrophotometer. Determination of the optimum condition was carried out at 40 ppm Cd(II, 125 rpm and 0,1 g adsorbent. Calculation of adsorpted Cd(II based on its concentration in aqueous phase before and after adsorption process. The concentrations of Cd(II in aqueous phase after adsorption process  were determined by using Atomic Absorption Spectroscopy (AAS. Identified functional groups of chitosan-alumina were -OH (3466.39 cm-1, -NH amine (1625.15 cm-1, C=O (1703.30 cm-1, and Al-O (1302.07 cm-1. The optimum pH was reached at pH 7, optimum agitation time at 15 minutes, and adsorption capacity of chitosan-alumina was 15.35 ± 0.05 mg/g.   Keywords: adsorption, chitosan-alumina, characterization of adsorption

  16. [Characterization of alumina adobe and sintered body of GI-infiltrated ceramic].

    Science.gov (United States)

    Wang, H; Chao, Y; Liao, Y; Liang, X; Zhu, Z; Gao, W

    2001-06-01

    This study was conducted to elucidate the mechanism of formation of porous structure by investigating the porosity of the alumina adobe and sintered body of GI-II Infiltrate Ceramic, and its role in strengthening and toughening this kind of ceramic composite. The alumina powder size-mass distribution was obtained by BI-XDC powder size analysis device; the open pore parameters of alumina adobe and sintered body were analyzed using the mercury pressure method. Their fracture surfaces were observed under scanning electronic microscope. Fine powder had two main size groups of 0.09-0.1 micron and 0.2-0.5 micron, respectively, and coarse powder, with size between 1.5 to 4.5 microns, occupied the majority of powder mass. Alumina adobe's pores became larger after sintering. The median pore radii of adobe and sintered body were 0.2531 micron and 0.3081 micron, respectively; the average pore radii changed from 0.0956 micron to 0.1102 micron. Under scanning electronic microscope, fine alumina powders were fused partially together and their surfaces were blunted, but coarse powders did not show such phenomena. The alumina size distribution contributes to the formation of porous structure of alumina sintered body. This porous structure is not only the shape skeleton but also the mechanical skeleton of GI-II Infiltrated Ceramic. It plays an important role in raising the mechanical properties of this kind of ceramic composite.

  17. Preparation and electrochemical performance of sulfur-alumina cathode material for lithium-sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Kang [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China); Wang, Shengping, E-mail: spwang@cug.edu.cn [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China); Zhang, Hanyu; Wu, Jinping [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China)

    2013-06-01

    Highlights: ► Micron-sized alumina was synthesized as adsorbent for lithium-sulfur batteries. ► Sulfur-alumina material was synthesized via crystallizing nucleation. ► The Al{sub 2}O{sub 3} can provide surface area for the deposition of Li{sub 2}S and Li{sub 2}S{sub 2}. ► The discharge capacity of the battery is improved during the first several cycles. - Abstract: Nano-sized sulfur particles exhibiting good adhesion with conducting acetylene black and alumina composite materials were synthesized by means of an evaporated solvent and a concentrated crystallization method for use as the cathodes of lithium-sulfur batteries. The composites were characterized and examined by X-ray diffraction, environmental scanning electron microscopy and electrochemical methods, such as cyclic voltammetry, electrical impedance spectroscopy and charge–discharge tests. Micron-sized flaky alumina was employed as an adsorbent for the cathode material. The initial discharge capacity of the cathode with the added alumina was 1171 mAh g{sup −1}, and the remaining capacity was 585 mAh g{sup −1} after 50 cycles at 0.25 mA cm{sup −2}. Compared with bare sulfur electrodes, the electrodes containing alumina showed an obviously superior cycle performance, confirming that alumina can contribute to reducing the dissolution of polysulfides into electrolytes during the sulfur charge–discharge process.

  18. Epoxy/α-alumina nanocomposite with high electrical insulation performance

    Directory of Open Access Journals (Sweden)

    Yun Chen

    2017-10-01

    Full Text Available An experimental study was conducted to improve the electrical insulation of epoxy resin. The effects of boehmite, γ-alumina and α-alumina nanoparticles on the volume resistivity, dielectric strength and glass transition temperature of epoxy nanocomposites were investigated. The results showed that α-alumina nanoparticles displayed obvious advantages in enhancing electrical insulation performance of epoxy nanocomposites, compared to boehmite and γ-alumina nanoparticles. The direct current volume resistivity and breakdown strength of epoxy nanocomposite with 2.0 wt% α-alumina nanoparticles was improved to 2.2 × 1018 Ω cm and 76.1 kV mm−1 respectively. And these improved values of electrical insulation properties are much higher than these of epoxy nanocomposites reported in previous studies. The main reason of these improvements may be that the epoxy/α-alumina interaction zone was enhanced by crosslink. Keywords: Nanocomposite, Epoxy resin, Insulation, α-alumina

  19. Topotactic preparation of textured alumina ceramics from dehydroxylation of gibbsite films

    Energy Technology Data Exchange (ETDEWEB)

    Louaer, Seif-Eddine; Wang, Yao, E-mail: yao@buaa.edu.cn; Guo, Lin, E-mail: guolin@buaa.edu.cn

    2014-11-14

    In this paper, textured alumina ceramics were prepared from dehydroxylation of gibbsite films and the pseudomorphic and topotactic nature of the dehydroxylation of textured gibbsite films has been investigated. First, the precursor film with a (001)-textured structure was obtained via vacuum filtration deposition of diluted aqueous suspensions of gibbsite nanoplatelets. Subsequently, (001)-textured α-alumina ceramics were successfully achieved by sintering of the deposited gibbsite films without addition of α-alumina seeds. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) results show that, during the phase transition from gibbsite to α-alumina, both layered morphology and crystal's axis orientation have been retained to a considerable extent. For the first time, a direct XRD evidence of gibbsite topotactic dehydroxylation to the α-alumina phase is presented. It is believed that the method described here exploits gibbsite's pseudomorphic and topotactic dehydroxylation, not on individual particles scale but on a bulk form. The resulting structure can be considered as inorganic scaffolds which can have applications for fabrication of dense, textured alumina-based ceramics and other layered/textured nanocomposites. - Highlights: • Gibbsite nanoplatelets were assembled on their basal plane to form (001)-textured films. • Textured alumina ceramics were prepared by sintering textured gibbsite films without addition of α-alumina seeds. • Both pseudomorphic and topotactic aspects were exploited in bulk form instead of individual nanoparticulate size. • Direct XRD evidence of the topotactic dehydroxylation from gibbsite to α-alumina is presented in this work.

  20. Topotactic preparation of textured alumina ceramics from dehydroxylation of gibbsite films

    International Nuclear Information System (INIS)

    Louaer, Seif-Eddine; Wang, Yao; Guo, Lin

    2014-01-01

    In this paper, textured alumina ceramics were prepared from dehydroxylation of gibbsite films and the pseudomorphic and topotactic nature of the dehydroxylation of textured gibbsite films has been investigated. First, the precursor film with a (001)-textured structure was obtained via vacuum filtration deposition of diluted aqueous suspensions of gibbsite nanoplatelets. Subsequently, (001)-textured α-alumina ceramics were successfully achieved by sintering of the deposited gibbsite films without addition of α-alumina seeds. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) results show that, during the phase transition from gibbsite to α-alumina, both layered morphology and crystal's axis orientation have been retained to a considerable extent. For the first time, a direct XRD evidence of gibbsite topotactic dehydroxylation to the α-alumina phase is presented. It is believed that the method described here exploits gibbsite's pseudomorphic and topotactic dehydroxylation, not on individual particles scale but on a bulk form. The resulting structure can be considered as inorganic scaffolds which can have applications for fabrication of dense, textured alumina-based ceramics and other layered/textured nanocomposites. - Highlights: • Gibbsite nanoplatelets were assembled on their basal plane to form (001)-textured films. • Textured alumina ceramics were prepared by sintering textured gibbsite films without addition of α-alumina seeds. • Both pseudomorphic and topotactic aspects were exploited in bulk form instead of individual nanoparticulate size. • Direct XRD evidence of the topotactic dehydroxylation from gibbsite to α-alumina is presented in this work

  1. Rare earth-doped alumina thin films deposited by liquid source CVD processes

    Energy Technology Data Exchange (ETDEWEB)

    Deschanvres, J.L.; Meffre, W.; Joubert, J.C.; Senateur, J.P. [Ecole Nat. Superieure de Phys. de Grenoble, St. Martin d`Heres (France). Lab. des Materiaux et du Genie Phys.; Robaut, F. [Consortium des Moyens Technologiques Communs, Institut National Polytechnique de Grenoble, BP 75, 38402 St Martin d`Heres (France); Broquin, J.E.; Rimet, R. [Laboratoire d`Electromagnetisme, Microondes et Optoelectronique, CNRS-Ecole Nationale Superieure d`Electronique et Radioelectricite de Grenoble, BP 257, 38016 Grenoble, Cedex (France)

    1998-07-24

    Two types of liquid-source CVD processes are proposed for the growth of rare earth-doped alumina thin films suitable as amplifying media for integrated optic applications. Amorphous, transparent, pure and erbium- or neodymium-doped alumina films were deposited between 573 and 833 K by atmospheric pressure aerosol CVD. The rare earth doping concentration increases by decreasing the deposition temperature. The refractive index of the alumina films increases as a function of the deposition temperature from 1.53 at 573 K to 1.61 at 813 K. Neodymium-doped films were also obtained at low pressure by liquid source injection CVD. (orig.) 7 refs.

  2. Remote microwave plasma enhanced chemical vapor deposition (RMPECVD) of silica and alumina films

    Energy Technology Data Exchange (ETDEWEB)

    Desmaison, J.; Hidalgo, H.; Tristant, P.; Naudin, F.; Merle, D. [Limoges Univ. (France). Lab. de Sciences des Procedes Ceramiques et Traitements de Surface

    2002-07-01

    Alumina or silica are attractive as insulation and protective layers for sensitive substrates. Oxides are deposited by remote microwave plasma enhanced chemical vapor deposition (RMPECVD) using an oxygen plasma and a mixture of precursor gas silane or trimethylaluminum (TMA) diluted in argon, respectively for silica and alumina, injected in the afterglow. This technique allows to deposit films of SiO{sub 2} and Al{sub 2}O{sub 3} with satisfactory characteristics (density, etch rate, stoichiometry) and high deposition rate. The comparison of the best deposition conditions reveals that in case of alumina higher temperatures and lower pressures are needed. (orig.)

  3. Radiation degradation in the mechanical properties of Polyetheretherketone–alumina composites

    International Nuclear Information System (INIS)

    Lawrence, Falix; Mallika, C.; Kamachi Mudali, U.; Natarajan, R.; Ponraju, D.; Seshadri, S.K.; Sampath Kumar, T.S.

    2012-01-01

    Polyetheretherketone (PEEK) is extensively employed in corrosive and radiation environments. To improve the radiation tolerance of PEEK in the presence of high energetic radiation, PEEK was reinforced with micron sized alumina powder (5–25% by weight) and PEEK–alumina composite sheets fabricated were irradiated to 10 MGy. Mechanical properties of the irradiated composites revealed significant reduction in the degradation of PEEK with addition of alumina as the polymer reinforced with ceramic additives is expected to increase the interface area of the constituents in the system resulting in an improvement in the performance of the reinforced material.

  4. From alumina nanopores to nanotubes: dependence on the geometry of anodization system.

    Science.gov (United States)

    Feil, Adriano F; da Costa, Marlla V; Migowski, Pedro; Dupont, Jaïrton; Teixeira, Sérgio R; Amaral, Lívio

    2011-03-01

    The Conventional anodization of commercial aluminum sheets with a phosphoric acid electrolyte was employed for the preparation of alumina nanopore and/or nanotube structures. Modifying the system geometry (the ratio of platinum to aluminum electrode areas) controlled the nature of the anodization process (mild to hard). Nanotube formation was observed after low temperature preferential chemical etching of the defective corners of the hexagonal alumina cells using the same solution from the anodization process. Electrode geometry can be used to combine mild and hard anodization with low temperature etching to tune the alumina morphology from 100% nanopores to 100% nanotubos coverage.

  5. Structural analysis of anodic porous alumina used for resistive random access memory

    International Nuclear Information System (INIS)

    Lee, Jeungwoo; Nigo, Seisuke; Kato, Seiichi; Kitazawa, Hideaki; Kido, Giyuu; Nakano, Yoshihiro

    2010-01-01

    Anodic porous alumina with duplex layers exhibits a voltage-induced switching effect and is a promising candidate for resistive random access memory. The nanostructural analysis of porous alumina is important for understanding the switching effect. We investigated the difference between the two layers of an anodic porous alumina film using transmission electron microscopy and electron energy-loss spectroscopy. Diffraction patterns showed that both layers are amorphous, and the electron energy-loss spectroscopy indicated that the inner layer contains less oxygen than the outer layer. We speculate that the conduction paths are mostly located in the oxygen-depleted area.

  6. Crack growth resistance under thermal shock loading of alumina

    Energy Technology Data Exchange (ETDEWEB)

    Saadaoui, M. [Ecole Mohammadia d`Ingenieurs (EMIL), Rabat (Morocco); Fantozzi, G. [GEMPPM-UMR CNRS 5510, INSA Lyon, Villeurbanne (France)

    1998-06-01

    Thermal shock experiments, conducted in an apparatus in which all the parameters can be controlled, are modelled by a two dimensional cooling model, allowing a precise determination of the induced stress intensity factors (SIF). Fracture mechanics analysis in terms of stress intensity factors is applied to determine R-curve behaviour of indentation cracks in alumina materials subjected to thermal shock. The instant of unstable crack growth was obtained by acoustic emission (AE). As in bending tests, the coarse grained material showed a more pronounced R-curve behaviour than the fine grained material. The results are discussed considering the influence of the R-curve behaviour on the retained strength after thermal shock. (orig.) 25 refs.

  7. Zirconia / Alumina Composite Foams with Calcium Phosphate Coating

    Directory of Open Access Journals (Sweden)

    Lenka Novotná

    2016-06-01

    Full Text Available In this study, mechanical properties of calcium phosphate foams were enhanced by zirconia/alumina porous cores prepared by polymer replica technique. This technique was chosen to ensure interconnected pores of optimal size for cell migration and attachment. The porosity of ZA cores (50 – 99% was controlled by multistep impregnation process, the size of pore windows was 300 – 500 μm. Sintered ZA cores were impregnated by hydroxyapatite or β-tricalcium phosphate slurry to improve bioactivity. The bone like apatite layer was formed on coatings when immersed in a simulated body fluid. Neither of tested materials was cytotoxic. Thus, the composite foam can be potentially used as a permanent substitute of cancellous bone.

  8. Electroless Fabrication of Cobalt Alloys Nanowires within Alumina Template

    Directory of Open Access Journals (Sweden)

    Nazila Dadvand

    2007-01-01

    Full Text Available A new method of nanowire fabrication based on electroless deposition process is described. The method is novel compared to the current electroless procedure used in making nanowires as it involves growing nanowires from the bottom up. The length of the nanowires was controlled at will simply by adjusting the deposition time. The nanowires were fabricated within the nanopores of an alumina template. It was accomplished by coating one side of the template by a thin layer of palladium in order to activate the electroless deposition within the nanopores from bottom up. However, prior to electroless deposition process, the template was pretreated with a suitable wetting agent in order to facilitate the penetration of the plating solution through the pores. As well, the electroless deposition process combined with oblique metal evaporation process within a prestructured silicon wafer was used in order to fabricate long nanowires along one side of the grooves within the wafer.

  9. Current Trends in Nanoporous Anodized Alumina Platforms for Biosensing Applications

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    Ganesan Sriram

    2016-01-01

    Full Text Available Pristine aluminum (Al has received great deal of attention on fabrication of nanoporous anodized alumina (NAA with arrays of nanosized uniform pores with controllable pore sizes and lengths by the anodization process. There are many applications of NAA in the field of biosensors due to its numerous key factors such as ease of fabrication, high surface area, chemical stability and detection of biomolecules through bioconjugation of active molecules, its rapidness, and real-time monitoring. Herein, we reviewed the recent trends on the fabrication of NAA for high sensitive biosensor platforms like bare sensors, gold coated sensors, multilayer sensors, and microfluidic device supported sensors for the detection of various biomolecules. In addition, we have discussed the future prospectus about the improvement of NAA based biosensors for the detection of biomolecules.

  10. Fatigue strength testing of LTCC and alumina ceramics bonds

    Science.gov (United States)

    Dąbrowski, A.; Matkowski, P.; Golonka, L.

    2012-12-01

    In this paper the results of fatigue strength tests of ceramic joints are presented. These tests have been performed on the samples subjected to thermal and vibration fatigue as well as on the reference samples without any additional loads. The main goal of the investigation was to determine the strength of hybrid ceramics joints using tensile testing machine. The experiment enabled evaluation of fatigue effects in the mentioned joints. Geometry of test samples has been designed according to FEM simulations, performed in ANSYS FEM environment. Thermal stress as well as the stress induced by vibrations have been analyzed in the designed model. In the experiments two types of ceramics have been used — LTCC green tape DP951 (DuPont) and alumina ceramic tape. The samples have been prepared by joining two sintered ceramic beams made of different types of material. The bonds have been realized utilizing low temperature glass or a layer of LTCC green tape.

  11. Microstructural features of alumina refractories with mullite-zirconia aggregates

    Directory of Open Access Journals (Sweden)

    Ferrari, C. R.

    2003-02-01

    Full Text Available Refractory materials are often subjected to high temperatures and loads and their performance depends on their microstructural evolution during use. In this context, microstructural changes were monitored in alumina-based refractories containing mullite-zirconia aggregates and heat-treated at 1400°C and 1500°C for 2, 6, and 18 days. With the purpose of inducing in situ mullite formation, bricks containing microsilica were also prepared and heat-treated at 1500°C for 6 days for the sake of comparison. These heat treatments allowed for an evaluation of the use of refractories from the standpoint of temperature and time. In this work, scanning electron microscopy and X-ray diffraction analyses were made to identify the phases in the materials. The Rietveld method was also used for quantitative phase analyses. Interfacial reactions occurred between alumina and aggregates and between alumina and microsilica, causing the system to become mullitized. The effect of in situ-formed mullite was particularly evident in the results of the modulus of rupture of the materials containing microsilica. Creep tests revealed a reduction in the creep rate of materials treated at 1500°C for 18 days.

    El comportamiento de los materiales refractarios, cuando sometidos a altas temperaturas y a grandes esfuerzos mecánicos, está íntimamente relacionado con la evolución microestuctural, durante su uso. En este contexto, fue realizado un estudio de la evolución microestructural de los materiales refractarios de alumina conteniendo diferentes porcentajes de agregado de mullita–circona, sometidos a tratamientos térmicos por 2, 6 y 18 días, en temperaturas de 1400 y 1500oC. Fueron confeccionados, algunos ladrillos conteniendo microsílice, con la idea de se introducir la formación de mullita en situ. Para la comparación de los ladrillos, fueron realizados tratamientos térmicos por un periodo de 6 días en 1500oC. Estos tratamientos térmicos permitieron

  12. Titanium nitride stamps replicating nanoporous anodic alumina films

    International Nuclear Information System (INIS)

    Navas, D; Sanchez, O; Asenjo, A; Jaafar, M; Baldonedo, J L; Vazquez, M; Hernandez-Velez, M

    2007-01-01

    Fabrication of nanostructured TiN films by magnetron sputtering using nanoporous anodic alumina films (NAAF) as substrates is reported. These hard nanostructured films could be used for pre-patterning aluminium foils and to obtain nanoporous films replicating the starting NAAF over a wide range of pore diameters and spacings. Pre-patterned Al foils are obtained by compression with pressures lower than those previously reported, then a new NAAF can be fabricated by means of only one anodization process. As an example, one of the TiN stamps was used for pre-patterning an Al foil at a pressure of 200 kg cm -2 and then it was anodized in oxalic acid solution obtaining the corresponding replica of the starting NAAF

  13. Ordered Nanomaterials Thin Films via Supported Anodized Alumina Templates

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    Mohammed eES-SOUNI

    2014-10-01

    Full Text Available Supported anodized alumina template films with highly ordered porosity are best suited for fabricating large area ordered nanostructures with tunable dimensions and aspect ratios. In this paper we first discuss important issues for the generation of such templates, including required properties of the Al/Ti/Au/Ti thin film heterostructure on a substrate for high quality templates. We then show examples of anisotropic nanostructure films consisting of noble metals using these templates, discuss briefly their optical properties and their applications to molecular detection using surface enhanced Raman spectroscopy. Finally we briefly address the possibility to make nanocomposite films, exemplary shown on a plasmonic-thermochromic nanocomposite of VO2-capped Au-nanorods.

  14. Quantitative convergent beam electron diffraction measurements of bonding in alumina

    International Nuclear Information System (INIS)

    Johnson, A.W.S.

    2002-01-01

    Full text: The QCBED technique of measuring accurate structure factors has been made practical by advances in energy filtering, computing and in the accurate measurement of intensity. Originally attempted in 1965 by the late Peter Goodman (CSIRO, Melbourne) while working with Gunter Lehmpfuhl (Fritz Haber Institut, Berlin), QCBED has been successfully developed and tested in the last decade on simple structures such as Si and MgO. Our work on Alumina is a step up in complexity and has shown that extinction in X-ray diffraction is not correctable to the precision required. In combination with accurate X-ray diffraction, QCBED promises to revolutionize the accuracy of bonding charge density measurements, experimental results which are of significance in the development of Density Functional Theory used in predictive chemistry. Copyright (2002) Australian Society for Electron Microscopy Inc

  15. Adsorption of chromium onto activated alumina: kinetics and thermodynamics studies.

    Science.gov (United States)

    Marzouk, Ikhlass; Dammak, Lassaad; Hamrouni, Béchir

    2013-02-01

    In this study, the removal of chromium (VI) by adsorption on activated alumina was investigated and the results were fitted to Langmuir, Freundlich, Dubinin-Redushkevich, and Temkin adsorption models at various temperatures. The constants of each model were evaluated depending on temperature. Thermodynamic parameters for the adsorption system were determined at 10, 25 and 40 degrees C. (deltaH degrees = -21.18 kJ x mol(-1); deltaG degrees = -8.75 to -7.43 kJ x mol(-1) and deltaS degrees = -0.043 kJ x K(-1) x mol(-1)). The obtained values showed that chromium (VI) adsorption is a spontaneous and exothermic process. The kinetic process was evaluated by first-order, second-order and Elovich kinetic models.

  16. Recovering metals from red mud generated during alumina production

    Science.gov (United States)

    Piga, Luigi; Pochetti, Fausto; Stoppa, Luisa

    1993-11-01

    There is growing interest in processing and utilizing the red mud by-product of the Bayer process for alumina extraction from bauxite. This interest stems largely from the environmental impacts associated with red mud and the storage costs involved. Furthermore, complete utilization of the raw materials, in this case bauxite, meets an ecological concept while ensuring raw material conservation. To prepare this article, the authors perused approximately 100 patents and articles in order to provide a concise description of the methods of storing red mud and its uses as a flocculant or construction material and in other minor applications. Special attention has been given to the methods developed for recovering metals contained in the red mud.

  17. Characterization of AMC commercial bricks with different alumina qualities

    International Nuclear Information System (INIS)

    Muñoz, V.; Camerucci, Maria A.; Martinez, A.G. Tomba

    2011-01-01

    The study of commercial bricks Al 2 O 3 -MgO-C (AMC) has some advantages over the analysis of materials prepared in the laboratory, but requires a complete characterization. This paper presents the results of the characterization of commercial bricks AMC with different types of alumina aggregates used in ladles floor. The same is done by several complementary techniques: XRD, DTA / TGA, EPR, volume density and apparent porosity, dilatometric analysis, microstructural analysis by low magnification and scanning electron microscopy (SEM) coupled with analysis Energy dispersive X-ray (EDX) and determination of mechanical properties at room temperature (Young's modulus, stress and strain at fracture). The main characteristics and differences in the composition and microstructure, essential data for further analysis of the mechanical behavior and resistance to slag attack of these refractories, are determined. (author)

  18. Optical Basicity and Nepheline Crystallization in High Alumina Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Carmen P.; McCloy, John S.; Schweiger, M. J.; Crum, Jarrod V.; Winschell, Abigail E.

    2011-02-25

    The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.

  19. A method for the control of alumina concentration in aluminum reduction cells

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1992-01-01

    Full Text Available The paper presents a new method for the control of the concentration of the alumina in electrolysis cells for the production of aluminium. The method is based upon the well known fact that apparent resistivity of the cell is a function of the alumina concentration so that the resistivity has the lowest value around the concentration of three per cent and increases in both directions. The method uses the cross correlation between a perturbation of the feed flow of alumina into the cell and the resulting response in measured voltage across the cell. The cross-correlation is proportional to the slope of the resistivity against concentration curve, making it possible to control the alumina flow, to achieve a desired slope. The method has much in common with other methods presently in use which require a much more complicated computation scheme.

  20. Feasibility study of use alumina waste in compositions containing clay for the mullite synthesis

    International Nuclear Information System (INIS)

    Silva, V.J.; Dias, G.; Goncalves, W.P.; Santana, L.N.L.

    2016-01-01

    The reuse of alumina residue in addition to reducing environmental impacts can be used as raw material in ceramic masses to mullite produce. This study aims to obtain mullite from compositions containing clays and alumina residue used heating in a conventional oven. The raw materials were processed and characterized. Subsequently, these compositions were formulated containing precursors in appropriate proportions based on the stoichiometry of the mullite 3:2. Then, heat treatment was performed at temperatures of 1300 to 1400°C and 5°C rate/min. The products obtained were characterized by XRD, analyzing qualitatively and quantitatively the phases formed. The results showed that is possible, from compositions containing clays and alumina residue to obtain mullite as major phase (>70%) and high crystallinity (> 80%) The percentage of mullite approached the values obtained with the compositions containing alumina and clays. (author)