Integrated cutting machine programming and lot sizing in furniture industry

In this paper a mathematical model that combines lot-sizing and cutting-stock problems applied to the furniture industry is presented. The model considers the usual decisions of the lot sizing problems, as well as operational decisions related to the cutting machine programming. Two sets of a priori generated cutting patterns are used, industry cutting patterns and a class of n-group cutting patterns. A strategy to improve the utilization of the cutting machine is also tested. An optimization package was used to solve the model and the computational results, using real data from a furniture factory, show that a small subset of n-group cutting patterns provides good results and that the cutting machine utilization can be improved by the proposed strategy.

Introducing the Discriminative Paraconsistent Machine (DPM)

This paper introduces a new tool for pattern recognition. Called the Discriminative Paraconsistent Machine (DPM), it is based on a supervised discriminative model training that incorporates paraconsistency criteria and allows an intelligent treatment of contradictions and uncertainties. DPMs can be applied to solve problems in many fields of science, using the tests and discussions presented here, which demonstrate their efficacy and usefulness. Major difficulties and challenges that were overcome consisted basically in establishing the proper model with which to represent the concept of paraconsistency.

Usinabilidade e integridade superficial de implantes dentários

Pós-graduação em Engenharia Mecânica - FEIS

Microhardness of the enamel exposed to whitening dentifrices

The purpose of this study is to verify the effect of three different types of dentifrices on the superficial microhardness of bovine enamel. Methods: Forty-eight 4x4mm dental fragments were polished and randomly divided into 4 groups: GI, conventional silica-based dentifrice; GII, hydrogen peroxide-based dentifrice; GIII, carbamide peroxide-based dentifrice; and GIV, immersion in artificial saliva. After polished, the specimens received five indentations of 25g static load, for 5 seconds. Subsequently, specimens from groups GI, GII and GIII were immersed in solution containing dentifrice and distilled water, in weight proportion of 1:2, for 15 minutes daily. After this period, fragments were rinsed in tap water and stored in artificial saliva at 37oC. This procedure was repeated for 21 days and then a new analysis of the microhardness was performed. Results and conclusion: The results were submitted to ANOVA and Fisher’s test at 5%. It was concluded that all samples treated with dentifrices showed hardness decrease, being most pronounced in dentifrices containing peroxide.

Effect of different light-curing techniques on hardness of a microhybrid dental composite resin

Coordenação de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Effect of sodium hypochlorite under several formulations on root canal dentin microhardness

Aim The aim of the present study was to evaluate the effect of three different formulations of sodium hypochlorite on the microhardness of root canal dentin in cervical and apical segments. Methods Twenty-four extracted human teeth had their roots sectioned along their long axes in a buccolingual direction. One half of each root was selected, and transversely sectioned resulting in two segments, cervical and apical, with similar lengths. The specimens were divided into three groups (n = 16), according to the sodium hypochlorite formulation used: (a) group 1, 2.5% sodium hypochlorite; (b) group 2, Chlor-XTRA; and (c) group 3, 5.5% sodium hypochlorite gel. These groups were subdivided in two subgroups (n = 8): cervical and apical root segments. Before testing the substances, dentin microhardness was measured on each section, 100 μm from the root canal with a Knoop tester. After 15 min of application, a new measurement was performed on each segment. Data were collected and registered for statistical treatment. Results In both segments, the substances reduced dentin microhardness. No differences were observed between the groups, independent of the analyzed segment (P > 0.05). Conclusions All substances reduced dentin microhardness. Chlor-XTRA and 5.5% sodium hypochlorite gel promoted a reduction similar to the 2.5% sodium hypochlorite solution.

Surface roughness and hardness of yttria stabilized zirconia (Y-TZP) after 10 years of simulated brushing

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Impact of chemical agents for surface treatments on microhardness and flexural strength of root dentin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions: microhardness and polarized light miscroscopy analyses

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

Effect of hydrogen peroxide concentration on enamel color and microhardness

Objectives: The aim of this study was to investigate the effect of hydrogen peroxide gels with different concentrations (20%, 25%, 30%, and 35%) on enamel Knoop microhardness (KNIT) as well as on changes in dental color (C).Methods: Cylindrical specimens of enamel/dentin (3-nun diameter and 2-nun thickness) were obtained from bovine incisors and randomly divided into six groups (n=20), according to the concentration of the whitening gel (20%, 25%, 30%, 35%, control, thickener). After polishing, initial values of KNH0 and color measurement, assessed by spectrophotometry using the CIE L*a*b* system, were taken from the enamel surface. The gels were applied on the enamel surface for 30 minutes, and immediate values of KNHi were taken. After seven days of being stored in artificial saliva, new measures of KNH7 and color (L-7* a(7)* b(7)*, for calculating Delta E, Delta L, and Delta b) were made. Data were submitted to statistical analysis of variance, followed by Tukey test (p<0.05).Results: Differences in gel concentration and time did not influence the microhardness (p=0.54 and p=0.29, respectively). In relation to color changes, Delta E data showed that the 35% gel presented a higher color alteration than the 20% gel did (p=0.006).Conclusion: Bleaching with 35% hydrogen peroxide gel was more effective than with the 20% gel, without promoting significant adverse effects on enamel surface microhardness.

A comparison of microhardness of indirect composite restorative materials

The purpose of this study was to compare the microhardness of four indirect composite resins. Forty cylindrical samples were prepared according to the manufacturer s recommendations using a Teflon mold. Ten specimens were produced from each tested material, constituting four groups (n=10) as follows: G1 - Artglass; G2 - Sinfony; G3 - Solidex; G4 - Targis. Microhardness was determined by the Vickers indentation technique with a load of 300g for 10 seconds. Four indentations were made on each sample, determining the mean microhardness values for each specimen. Descriptive statistics data for the experimental conditions were: G1 - Artglass (mean ±standard deviation: 55.26 ± 1.15HVN; median: 52.6); G2 - Sinfony (31.22 ± 0.65HVN; 31.30); G3 - Solidex (52.25 ± 1.55HVN; 52.60); G4 - Targis (72.14 ± 2.82HVN; 73.30). An exploratory data analysis was performed to determine the most appropriate statistical test through: (I) Levene's for homogeneity of variances; (II) ANOVA on ranks (Kruskal-Wallis); (III) Dunn's multiple comparison test (0.05). Targis presented the highest microhardness values while Sinfony presented the lowest. Artglass and Solidex were found as intermediate materials. These results indicate that distinct mechanical properties may be observed at specific materials. The composition of each material as well as variations on polymerization methods are possibly responsibles for the difference found in microhardness. Therefore, indirect composite resin materials that guarantee both good esthetics and adequate mechanical properties may be considered as substitutes of natural teeth.

Effect of incorporation of remineralizing agents into bleaching gels on the microhardness of bovine enamel in situ

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

Cardiopulmonary bypass: development of John Gibbon's heart-lung machine

To provide a brief review of the development of cardiopulmonary bypass. A review of the literature on the development of extracorporeal circulation techniques, their essential role in cardiovascular surgery, and the complications associated with their use, including hemolysis and inflammation. The advancement of extracorporeal circulation techniques has played an essential role in minimizing the complications of cardiopulmonary bypass, which can range from various degrees of tissue injury to multiple organ dysfunction syndrome. Investigators have long researched the ways in which cardiopulmonary bypass may insult the human body. Potential solutions arose and laid the groundwork for development of safer postoperative care strategies. Steady progress has been made in cardiopulmonary bypass in the decades since it was first conceived of by Gibbon. Despite the constant evolution of cardiopulmonary bypass techniques and attempts to minimize their complications, it is still essential that clinicians respect the particularities of each patient's physiological function.

Microhardness of luting agents used for fiber post cementation submitted to thermo cycling

Aims and Objectives: The aim of this study was to analyze the microhardness of three resin cements used in cementing glass fiber posts in bovine incisor. The microhardness was analyzed in cervical, middle and apical thirds before and after thermocycling process. Materials and Methods: Bovine teeth were instrumented and divided into 3 groups composed of 10 teeth each. Then, the teeth were sectioned and obturated and had their canals prepared at a depth of 12mm. Once proceeded the desobturation, the roots and glass fiber posts were prepared for adhesive cementation. After cementation, the microhardness reading was carried out. After initial reading, the samples were placed in a thermocycler and subjected to 2,000 cycles and a new microhardness reading. The data collected were subjected to analysis of variance (ANOVA) and Turkey’s test. Results: It was observed a statistical difference among the microhardness of resin cements. However, the statistical difference of microhardness before and after thermocycling appeared only in group U-200. Conclusion: Thermocycling reduced microhardness values in all cements evaluated in this study. The autopolymerizing cement Multilink presented the most stable microhardness mean values after thermocycling in the coronal, middle and apical thirds.

Análise da interface adesiva entre pinos de fibra de vidro e dentina intrarradicular submetida à irrigação com diferentes agentes condicionantes

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