Avaliação da eficiência de corte de fresas Carbide em função dos métodos de esterilização físicos e químico. Análise gravimétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise morfológica e de resistência à flexão da interface ponta ativa/haste metálica em fresas carbide após o uso de esterilização

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relação desgaste-acabamento superficial em ferramentas de metal duro com revestimento triplo no torneamento de aços

Pós-graduação em Engenharia Mecânica - FEG

Esterilização de fresas carbide em fornos de micro-ondas domésticos. Efeito da capacidade. da potência, do meio da imersão, da quantidade e posição da amostra sobre o tempo de esposição

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avanços no torneamento utilizando um porta-ferramentas refrigerado internamente com fluido em mudança de fase

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

Use of Chemometric Tools to Determine the Source of Metals in Sediments of the Rivers of the Turvo/Grande Hydrographical Basin, Sao Paulo State, Brazil

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

Aspectos da furação do titânio 6Al4V com broca de aço rápido sinterizado e broca de metal duro

Pós-graduação em Engenharia Mecânica - FEG

A MICROSTRAIN COMPARISON OF PASSIVELY FITTING SCREW-RETAINED AND CEMENTED TITANIUM FRAMEWORKS

Statement of problem. An imprecise fit between frameworks and supporting dental implants in loaded protocols increases the strain transferred to the periimplant bone, which may impair healing or generate microgaps.Purpose. The purpose of this study was to investigate the microstrain between premachined 1-piece screw-retained frameworks (group STF) and screw-retained frameworks fabricated by cementing titanium cylinders to the prefabricated framework (group CTF). This procedure was developed to correct the misfit between frameworks and loaded implants.Material and methods. Four internal hexagon cylindrical implants were placed 10 mm apart in a polyurethane block by using the surgical guides of the corresponding implant system. Previously fabricated titanium frameworks (n=10) were divided into 2 groups. In group STF, prefabricated machined frameworks were used (n=5), and, in group CTF, the frameworks were fabricated by using a passive fit procedure, which was developed to correct the misfit between the cast titanium frameworks and supporting dental implants (n=5). Both groups were screw-retained under torque control (10 Ncm). Six strain gauges were placed on the upper surface of the polyurethane block, and 3 strain measurements were recorded for each framework. Data were analyzed with the Student t test (alpha=.05).Results. The mean microstrain values between the framework and the implants were significantly higher for group STF (2517 me) than for group CTF (844 me) (P<.05).Conclusions. Complete-arch implant frameworks designed for load application and fabricated by using the passive fit procedure decreased the strain between the frameworks and implants more than 1 piece prefabricated machined frameworks.

Vector Mode Analysis of Ring-Core Fibers: Design Tools for Spatial Division Multiplexing

Design tools have existed for decades for standard step-index fibers, with analytical expressions for cutoff conditions as a function of core size, refractive indexes, and wavelength. We present analytical expressions for cutoff conditions for fibers with a ring-shaped propagation region. We validate our analytical expressions against numerical solutions, as well as via asymptotic analysis yielding the existing solutions for standard step-index fiber. We demonstrate the utility of our solutions for optimizing fibers supporting specific eigenmode behaviors of interest for spatial division multiplexing. In particular, we address large mode separation for orbital angular momentum modes and fibers supporting only modes with a single intensity ring.

Influência de diferentes métodos de limpeza sobre a eficiência de corte e as características morfológicas de fresas Carbide

Introduction: Currently, there are many questions regarding the cleaning methods seeking greater efficiency and less loss of burs. Aim: the aim of this study was to evaluate the influence of cleaning methods on the cutting efficiency and morphological characteristics of stainless steel burs tungsten carbide (carbide). Materials and method: Thirty burs were divided into five groups (n = 5) according with the cleaning method: L1 - steel brush, L2 - nylon brush, L3 - ultrasound  +  distilled water, L4 - ultrasound + descaling solution and L5 - no cleaning method (control). The burs were used for the cutting of bovine enamel during six periods of 12 minutes each. After each period, the burs were cleaned (except L5 ) following the protocol established for each group. The cutting efficiency was determined by mass loss and morphological characteristics. Result: The average amount of wear after 72 minutes of use were L1  = 0.3558 g; L2  = 0.4275 g; L3  = 0.4652 g; L4  = 0.4396 g e L5  = 0.4854 g; significant differences in the time of use (p  <  0.001) and cleaning method (p  <  0.001). The L1 group showed the worst performance. Regardless of the experimental group, morphological analysis revealed alterations in the cutting blades soon after the first 12 minutes, being L1 the most affected group. Conclusion: The cleaning with wire brush was the most damaging method to the cutting efficiency and to the morphology of carbide burs.

Indirect resin onlay cemented with self-adhesive resin cement: a comprehensive clinical overview

Advances in adhesive technology and esthetic dental materials have permitted clinicians to perform conservative preparation of the dentition for onlay restorations. Indirect resin onlays are a great alternative to dental crowns for reestablishment the function and esthetic in teeth with great destruction.

Collective screening tools for early identification of dyslexia

Current response to intervention models (RTIs) favor a three-tier system. In general, Tier 1 consists of evidence-based, effective reading instruction in the classroom and universal screening of all students at the beginning of the grade level to identify children for early intervention. Non-responders to Tier 1 receive small-group tutoring in Tier 2. Nonresponders to Tier 2 are given still more intensive, individual intervention in Tier 3. Limited time, personnel and financial resources derail RTI's implementation in Brazilian schools because this approach involves procedures that require extra time and extra personnel in all three tiers, including screening tools which normally consist of tasks administered individually. We explored the accuracy of collectively and easily administered screening tools for the early identification of second graders at risk for dyslexia in a two-stage screening model. A first-stage universal screening based on collectively administered curriculum-based measurements was used in 45 7 years old early Portuguese readers from 4 second-grade classrooms at the beginning of the school year and identified an at-risk group of 13 academic low-achievers. Collectively administered tasks based on phonological judgments by matching figures and figures to spoken words [alternative tools for educators (ATE)] and a comprehensive cognitive-linguistic battery of collective and individual assessments were both administered to all children and constituted the second-stage screening. Low-achievement on ATE tasks and on collectively administered writing tasks (scores at the 25th percentile) showed good sensitivity (true positives) and specificity (true negatives) to poor literacy status defined as scores <= 1 SD below the mean on literacy abilities at the end of fifth grade. These results provide implications for the use of a collectively administered screening tool for the early identification of children at risk for dyslexia in a classroom setting.

Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent

Objective: The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods: Eighty blocks (8x8x4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5 degrees C and 55 degrees C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mu m Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (mu TBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5 degrees C and 55 degrees C, with a dwell time of 30 s in each bath) and mu TBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (alpha=0.05). Results: The mu TBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion: Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement.

Development of a comprehensive method for analyzing clerodane-type diterpenes and phenolic compounds from Casearia sylvestris Swartz (Salicaceae) based on ultra high performance liquid chromatography combined with chemometric tools

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