Effect of testing methods on the bond strength of resin to zirconia-alumina ceramic: microtensile versus shear test

This study tested the bond strength of a resin cement to a glass-infiltrated zirconia-alumina ceramic after three conditioning methods and using two test methods (shear-SBS versus microtensile-MTBS). Ceramic blocks for MTBS and ceramic disks for SBS were fabricated. Three surface conditioning (SC) methods were evaluated: (1) 110-mu m Al(2)O(3)+Silanization; (2) Chairside silica coating+silanization: (3) Laboratory silica coating+silanization. Following surface conditioning, the resin cement (Panavia F) was bonded to the conditioned ceramics. Although no statistically significant differences (p=0.1076) were seen between the test methods, results yielded with the different surface conditioning methods showed statistically significant differences (p<0.0001) (SC2=SC3>SC1.). As for the interaction between the factors, two-way ANOVA showed that it was not statistically significant (p=0.1443). MTBS test resulted in predominantly mixed failure (85%), but SBS test resulted in exclusively adhesive failure. on the effects of different surface conditioning methods, chairside and laboratory tribochemical silica coating followed by silanization showed higher bond strength results compared to those of aluminum oxide abrasion and silanization, independent of the test method employed.

Comparative study of 2 software programs for predicting profile changes in Class III patients having double-jaw orthognathic surgery

Introduction: Computer software can be used to predict orthognathic surgery outcomes. The aim of this study was to subjectively compare the soft-tissue surgical simulations of 2 software programs. Methods: Standard profile pictures were taken of 10 patients with a Class III malocclusion and a concave facial profile who were scheduled for double-jaw orthognathic surgery. The patients had horizontal maxillary deficiency or horizontal mandibular excess. Two software programs (Dentofacial Planner Plus [Dentofacial Software, Toronto, Ontario, Canada] and Dolphin Imaging [version 9.0, Dolphin Imaging Software, Canoga Park, Calif]) were used to predict the postsurgical profiles. The predictive images were compared with the actual final photographs. One hundred one orthodontists, oral-maxillofacial surgeons, and general dentists evaluated the images and were asked whether they would use either software program to plan treatment for, or to educate, their patients. Results: Statistical analyses showed differences between the groups when each point was judged. Dolphin Imaging software had better prediction of nasal tip, chin, and submandibular area. Dentofacial Planner Plus software was better in predicting nasolabial angle, and upper and lower lips. The total profile comparison showed no statistical difference between the softwares. Conclusions: The 2 types of software are similar for obtaining 2-dimensional predictive profile images of patients with Class III malocclusion treated with orthognathic surgery. (Am J Orthod Dentofacial Orthop 2010; 137: 452.e1-452.e5)

Effects of cement thickness and bonding on the failure loads of CAD/CAM ceramic crowns: Multi-physics FEA modeling and monotonic testing

Objective. To determine the influence of cement thickness and ceramic/cement bonding on stresses and failure of CAD/CAM crowns, using both multi-physics finite element analysis and monotonic testing.Methods. Axially symmetric FEA models were created for stress analysis of a stylized monolithic crown having resin cement thicknesses from 50 to 500 mu m under occlusal loading. Ceramic-cement interface was modeled as bonded or not-bonded (cement-dentin as bonded). Cement polymerization shrinkage was simulated as a thermal contraction. Loads necessary to reach stresses for radial cracking from the intaglio surface were calculated by FEA. Experimentally, feldspathic CAD/CAM crowns based on the FEA model were machined having different occlusal cementation spaces, etched and cemented to dentin analogs. Non-bonding of etched ceramic was achieved using a thin layer of poly(dimethylsiloxane). Crowns were loaded to failure at 5 N/s, with radial cracks detected acoustically.Results. Failure loads depended on the bonding condition and the cement thickness for both FEA and physical testing. Average fracture loads for bonded crowns were: 673.5 N at 50 mu m cement and 300.6 N at 500 mu m. FEA stresses due to polymerization shrinkage increased with the cement thickness overwhelming the protective effect of bonding, as was also seen experimentally. At 50 mu m cement thickness, bonded crowns withstood at least twice the load before failure than non-bonded crowns.Significance. Occlusal "fit" can have structural implications for CAD/CAM crowns; pre-cementation spaces around 50-100 mu m being recommended from this study. Bonding benefits were lost at thickness approaching 450-500 mu m due to polymerization shrinkage stresses. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The resistivity piezocone for high resolution geo-environmental site investigation: A Brazilian example

A suit able decision-making on managing a contaminated site characterization program is strongly dependent of the diagnosis process. A detailed diagnosis can be done based on a Conceptual Site Model (CSM) elaboration using high resolution site characterization tools. The piezocone (CPTu) test is a high resolution tool which allows attaching several specific sensors, like the resistivity probe. This hybrid device is called the resistivity piezocone (RCPTu). A simulated geo-environmental site characterization program was performed on an erosion site using different tools (direct push tools soil samplers, hollow stem auger (HSA) drilling and RCPTu tests) to develop the CSM for a site similar to the Brazilian conditions. It was observed a good agreement between the site profiles interpreted by the different methods. The resistivity sensor attached to the piezocone improved the interpretation and the decision-making process on site was significantly better for the CSM elaboration. The RCPTu test data also allowed identifying the hydrogeological heterogeneities. The present study shows that the RCPTu test is also a useful and powerful tool to development an accurate CSM in a Brazilian condition, especially in an approach that prioritizes high resolution geo-environmental investigation. © 2013 Taylor & Francis Group.

Previsão do comportamento de estruturas de contenção atirantadas utilizando o software FTOOL

Population growth, together with the gradual social ascent in Brazil, reflects at the growing need for better use of urban spaces. In this context, the amount of new buildings to meet the demand in property market, the needs for creating new roads and highways, among others, make the use of geotechnical works and, more specifically, retaining walls, more and more common. One of the simplest solutions for underground works is the use of retaining structures using tie back walls for soil support, therefore, the present work deals with this kind of structures. This paper proposes the use of FTOOL software testing in predicting deformations in tie back walls, by comparing simulations of the presented model to a real and measured deformation case in Guabirotuba Formation (PR). The results showed the importance of defining the parameters such as stiffness and curtain geometry, as well as the definition of representative loads acting on it. Also, it was pointed out that the passive response of the steel rods depends on the horizontal displacement of the wall. The study concluded that the program generates very representative results when compared to field data and seems to be a promising tool for tie back structures displacement predictions

Portable Hardness tester for timber classification

Hardness is a property largely used in material specifications, mechanical and metallurgical research and quality control of several materials. Specifically for timber, Janka hardness is a simple, quick and easy test, with good correlations with the compression parallel to grain strength, a strong reference in structural classification for this material. More recently, international studies have reported the use of Brinell hardness for timber assessment which resumes the advantages previously mentioned for Janka hardness and make it easier to be performed in the field, especially because of the lower magnitude of the involved loads. A first generation of an equipment for field evaluation of hardness in wood - Portable Hardness tester for wood - based on Brinell hardness has already been developed by the Research Group on Forest Products from FCA/UNESP, Brazil, with very good correlations between the evaluated hardness and several other mechanical properties of the material when performing tests with different species of native and reforested wood (traditionally used as ties - sleepers - in railways). This paper presents results obtained in the experimental program with the first generation of this equipment and preliminary tests with its second generation, which uses accelerometers to substitute the indentation measurements in wood. For the first generation of the equipment functional and calibration tests were carried out using 16 native and reforestation timber lots, among there E. citriodora, E. tereticornis, E. saligna, E. urophylla, E. grandis, Goupia glabra and Bagassa guianenses, with different origins and ages. The results obtained confirm its potential in the classification of specimens, with inclusion errors varying from 4.5% to 16.6%.

In Vitro Susceptibility of Environmental Isolates of Exophiala dermatitidis to Five Antifungal Drugs

Several dematiaceous fungi frequently isolated from nature are involved in cases of superficial lesions to lethal cerebral infections. Antifungal susceptibility data on environmental and clinical isolates are still sparse despite the advances in testing methods. The objective of this study was to examine the activities of 5-flucytosine, amphotericin B, itraconazole, voriconazole and terbinafine against environmental isolates of Exophiala strains by minimum inhibition concentration (MIC) determination. The strains were obtained from hydrocarbon-contaminated soil, ant cuticle and fungal pellets from the infrabuccal pocket of attine gynes. Broth microdilution assay using M38-A2 reference methodology for the five antifungal drugs and DNA sequencing for fungal identification were applied. Terbinafine was the most active drug against the tested strains. It was observed that amphotericin B was less effective, notably against Exophiala spinifera, also studied. High MICs of 5-flucytosine against Exophiala dermatitidis occurred. This finding highlights the relevance of studies on the antifungal resistance of these potential opportunistic species. Our results also contribute to a future improvement of the standard methods to access the drug efficacy currently applied to black fungi. © 2012 Springer Science+Business Media Dordrecht.

Desenvolvimento de metodologia para a obtenção da cubicagem de madeira em toras empilhadas através de imagens digitais

Obtaining accurate estimates of the volume of stacked wood is important in view of the increasing value of wood as raw material. Therefore, the forest companies have become increasingly concerned about the methods currently used to convert cubic meters for stereo. In this context, emerged the need of optimizing the measurement process and accuracy of the volume of stacked wood. For this, companies have been testing methods with greater efficiency, speed and low operating cost. Existing methods made through approximate equations, and also by determining the conversion factor, called the stacking factor (Fe), are questioned, due to errors and inaccuracies. The use of digital photographs is an alternative method that would minimize operator intervention, allowing greater control and speed the process, thus eliminating part of the imprecision of the traditional method. The use of the method is viable, due to present an error of about 10% while traditional methods showed an error of 17%

Avaliação de fração volumétrica de austenita retida e martensita em aço trip 800 utilizando três métodos diferentes

In the second half of the last century the automobile industries suffered from the petroleum crisis caused mainly by the wars in the Middle East. These crises led the automakers rethink their vehicles. One of the most important events after that was the adoption of new steels by the industry. One example is the TRIP steels (Transformationinduced plasticity). It is known that the macroscopic behavior of a material is strongly dependent on its microstructure and therefore the quantitative metallography is important to understand and relate the material properties to its microstructure. In this work, different specimens of TRIP steels were etched using LePera reagent. The obtained images were analyzed using digital processing. Using the ImageJ software the methods threshold and watershed were studied as well as a comparison with the ASTM E562 standard. The methods were compared and finally the morphological characteristics and volumetric fraction of the retained austenite and martensite phases were analyzed. The results showed that the threshold led to a higher number of identified grains with lower mean area and total area fraction than the watershed method and ASTM standard

Lifetime comparison of Y-TZP/porcelain crowns under different loading conditions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Some experiments with high order compact methods using a computer algebra software - Part I

We consider a procedure for obtaining a compact fourth order method to the steady 2D Navier-Stokes equations in the streamfunction formulation using the computer algebra system Maple. The resulting code is short and from it we obtain the Fortran program for the method. To test the procedure we have solved many cavity-type problems which include one with an analytical solution and the results are compared with results obtained by second order central differences to moderate Reynolds numbers. (c) 2005 Elsevier B.V. All rights reserved.

Some experiments with high order compact methods using a computer algebra software - Part II (non-uniform grid)

We generalize a procedure proposed by Mancera and Hunt [P.F.A. Mancera, R. Hunt, Some experiments with high order compact methods using a computer algebra software-Part 1, Appl. Math. Comput., in press, doi: 10.1016/j.amc.2005.05.015] for obtaining a compact fourth-order method to the steady 2D Navier-Stokes equations in the streamfunction formulation-vorticity using the computer algebra system Maple, which includes conformal mappings and non-uniform grids. To analyse the procedure we have solved a constricted stepped channel problem, where a fine grid is placed near the re-entrant corner by transformation of the independent variables. (c) 2006 Elsevier B.V. All rights reserved.

Projeto mecânico de um modelo para túnel de vento e validação de seus componentes à partir de simulações em software de elementos finitos

The objective of this study was to develop a model that allows testing in the wind tunnel at high angles of attack and validates its most critical components by analyzing the results of simulations in finite element software. During the project this structure suffered major loads identified during the flight conditions and, from these, we calculated the stresses in critical regions defined as the parts of the model that have higher failure probabilities. All aspects associated with Load methods, mesh refining and stress analysis were taken into account in this approach. The selection of the analysis software was based on project needs, seeking greater ease of modeling and simulation. We opted for the software ANSYS® since the entire project is being developed in CAD platforms enabling a friendly integration between software's modeling and analysis

Methods for evaluating the physiological potential of scarlet eggplant (Solanum aethiopicum) seeds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic diversity and antifungal susceptibility testing of Trichosporon asahii isolated of Intensive Care Units patients

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)