Effect of postpolymerization method on the color stability of composite resins submitted to ultraviolet aging

The aim of this research was to evaluate the effect of postpolymerization method on the color stability of resin-based composites. Samples of direct and indirect restorative materials were polymerized with two photo-curing units (Visio photo-curing oven system and LED Elipar Freelight 2). All samples were submitted to an initial chromatic analysis using a spectrometer and submitted to ultraviolet-accelerated artificial aging. The direct material showed less color change than the indirect material, independent of the photo-activation method used. Samples photo cured with the LED system showed less change than those photo cured with the Visio system. The postpolymerization oven did not improve the color stability of direct and indirect resin-based composites.

Effects of dental bleaching on the color, translucency and fluorescence properties of enamel and dentin

The objective of this study was to evaluate the color, translucency and fluorescence of bovine enamel and dentin submitted to different bleaching modalities. Pairs of enamel and dentin discs (3 mm in diameter) were obtained from 150 bovine teeth. In 75 of the pairs, one specimen had the enamel removed (Dentin Group). The dentin was removed from one specimen of the remaining 75 pairs (Enamel Group) and the other specimen was left unaltered (Enamel + Dentin). The evaluation of color, translucency and fluorescence was performed with a spectrophotometer using the CIE L* a* b*. Each group was subdivided into three subgroups: Control, composed of specimens that were not bleached, and two experimental subgroups, bleached with either 10% carbamide peroxide (CP10%) or 35% hydrogen peroxide (HP35%). The CP10% bleaching gel was applied 2 h/day for 14 days. The HP35% bleaching agent was applied using two applications of 30 min each, with a one week interval between each application. When not being bleached, the specimens were immersed in artificial saliva. The color, translucency and fluorescence ratings were assessed using spectrophotometry 7 days after the treatment. Regarding color, significant differences were found between bleaching techniques in the groups Enamel and Enamel + Dentin, with a higher color difference for HP35%. Bleaching did not change the translucency of the dental tissues. There were significant differences for fluorescence for the HP35% subgroups of Dentin and Enamel + Dentin, and for the CP10% subgroup of Enamel. Dental bleaching changed the color and fluorescence of the dental tissues, however translucency was not affected.

Color stability of the artificial iris button in an ocular prosthesis before and after acrylic resin polymerization

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

Influence of whitening gel application protocol on dental color change

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

Cytotoxic and genotoxic effects of two hair dyes used in the formulation of black color

According to the International Agency for Research on Cancer (IARC), some hair dyes are considered mutagenic and carcinogenic in in vitro assays and exposed human populations. Epidemiological studies indicate that hairdressers occupationally exposed to hair dyes have a higher risk of developing bladder cancer. In Brazil, 26% of the adults use hair dye. In this study, we investigated the toxic effects of two hair dyes, Basic Red 51 (BR51) and Basic Brown 17 (BB17), which are temporary dyes of the azo group (R-N=N-R'), used in the composition of the black hair dye. To this end, MTT and trypan blue assays (cytotoxicity), comet and micronucleus assay (genotoxicity) were applied, with HepG2 cells. For cytotoxic assessment, dyes were tested in serial dilutions, being the highest concentrations those used in the commercial formula for hair dyes. For genotoxic assessment concentrations were selected according to cell viability. Results showed that both dyes induced significant cytotoxic and genotoxic effects in the cells, in concentrations much lower than those used in the commercial formula. Genotoxic effects could be related to the azo structure present in the composition of the dyes, which is known as mutagenic and carcinogenic. These results point to the hazard of the hair dye exposure to human health.

Multiculturalismo, diversidade cultural e cotidiano escolar: uma análise da temática em filmes de escola

This work has as its theme the multiculturalism, cultural diversity and their reflections in school everyday, more specifically on the interactions between the various subjects and social groups that make up a school and the teacher as mediator of the relationship between these guys. The theme Multiculturalism refers in the first instance, to the theoretical movement beginning in the mid-20th century in the United States and that spreads in the Western world as a way of tackling the conflicts generated depending on the economic issues, policies, and, in particular, cultural-ethnic, in an attempt to combat discrimination and prejudice, given the difficulties of individuals and groups to welcome and socialize with the plurality and cultural differences (SILVA; BRANDIM, 2008).At the same time, multiculturalism refers to cultural studies, through the Centre for Contemporary cultural studies, founded by em1964 Hoggart, and connected to the English language Department of the University of Birmingham in England.In contemporary times, due to the phenomenon of globalization and public policy to challenge prejudice and discrimination the subjects and social groups, regardless of color, creed, ethnicity, sexual orientation and nationality, this theme has been recurring in order to recognize plural identities and ensure and directly affects the school as a place of cultural diversity and conflicts generated by the very diversity.The present work aims to analyze and understand how the issue of multiculturalism and cultural diversity in school films. Our study will be based theoretically in Cultural Studies authors and uses the qualitative approach, working with movie content analysis of school, seeking to seize on the same relations of coexistence, conflicts and the mediations of teachers

Soft color enhancement of the production of J/psi's by neutrinos

We calculate the production of J/ψ mesons by neutrino-nucleon collisions in fixed target experiments. Soft color, often referred to as color evaporation effects, enhances production cross sections due to the contribution of color octet states. Though still small, J/ψ production may be observable in present and future experiments such as NuTeV and μ colliders. ©2001 The American Physical Society.

Composite resin color stability: influence of light sources and immersion media

This study evaluated the influence of light sources and immersion media on the color stability of a nanofilled composite resin. Conventional halogen, high-power-density halogen and high-power-density light-emitting diode (LED) units were used. There were 4 immersion media: coffee, tea, Coke® and artificial saliva. A total of 180 specimens (10 mm x 2 mm) were prepared, immersed in artificial saliva for 24 h at 37±1ºC, and had their initial color measured with a spectrophotometer according to the CIELab system. Then, the specimens were immersed in the 4 media during 60 days. Data from the color change and luminosity were collected and subjected to statistical analysis by the Kruskall-Wallis test (p<0.05). For immersion time, the data were subjected to two-way ANOVA test and Fisher's test (p<0.05). High-power-density LED (ΔE=1.91) promoted similar color stability of the composite resin to that of the tested halogen curing units (Jet Lite 4000 plus--ΔE=2.05; XL 3000--ΔE=2.28). Coffee (ΔE=8.40; ΔL=-5.21) showed the highest influence on color stability of the studied composite resin. There was no significant difference in color stability regardless of the light sources, and coffee was the immersion medium that promoted the highest color changes on the tested composite resin.

Bacterial oxycarotenoids added into broiler chickens ration modify breast meat color

Some markets around the world demand for well pigmented poultry products, what justifies the intentional use of synthetic additives in rations during breeding. The inconvenient for that practice most times is the elevated price of these products, beyond the argument of being chemicals, which may not be viable for some production systems. So, the aim of this experiment was to check on the ability of natural red oxycarotenoids produced by R. gelatinosus to modify broilers breast meat color. Bacterial biomass containing oxycarotenoids were added into Cobb broilers finisher diets at 0, 1.0, 2.0 and 3.0 g/kg and fed during 10 days (35-45 d). Five replicates (10 birds each) were performed. At days 35, 37, 39, 41, 43 and 45, 100 birds were slaughtered scalded, defeathered and eviscerated. Data on live and carcass weights were recorded. After cooling, color parameters of meat were determined on breast surface using a HunterLab XE Plus colorimeter calibrated with black and white standard tiles. Regression analysis was used for the investigation of relationships between days of consumption and biomass concentration on color values, live weight and carcass yield. Results showed that redness of breast meat was significantly influenced by the biomass concentration in a linear effect (P=0.0056) and also by the time of consumption, in a quadratic effect (P=0.0232). Days of consumption also affected yellowness and lightness with significant quadratic responses (P=0.0225 and P<0.0001, respectively). Birds live weight increased significantly during the application of the experimental diets (P<0.0001), showing no negative influence of the biomass administration. Also no deleterious effects derived from the application of the product were observed on carcass yield. So we concluded that R. gelatinosus oxycarotenoids present in the bacterial biomass can modify broilers breast meat color, performing as an alternative pigmenting additive in poultry production.

Yolks color definition by supplementing yellow and red xanthophylls to hen's diets

Egg yolk color may be controlled both by the concentration and the type of xanthophylls added to diets, with the aim of meeting consumers demand. The objectives of this work were to study how yellow and red xanthophylls present in laying hens` diets influence yolks colors and find the concentrations of these ingredients that meet the regional consumer desire. A factorial design 5 x 3 with 5 concentrations of yellow xanthophylls (lutein + zeaxantin 40%; 1.0, 1.25, 1.5, 1.75 and 2.0 mg/hen/d) and 3 concentrations of red xanthophylls (canthaxantin 10%; 0, 0.35, 0.7 mg/hen/d) was used. After a 30 d period receiving corn basal diets and water ad libitum, 60 White Dekalbe hens were distributed to receive the 15 dietary treatments in 4 replicates. Diets were provided daily at 110 g, during 21 d under 16 h light/8 h dark. Yolks colors were evaluated daily using the CIE L, a, b color space and the Roche color index. After the color stabilization, data were analyzed by ANOVA, regression analysis and Response Surface Methodology (MRS). Global acceptance for the Roche colors was evaluated with a 5 points hedonic scale and data were analyzed by Friedman and Dunn tests. Significance was established at 95% (P < 0.05). Regression analysis showed that the red xanthophylls content was the most important factor that defined L, a and b values for yolk color (P < 0.0001; square function), although its effect was significantly affected by the yellow xanthophylls contents (P = 0.0277; P < 0.0001; P = 0.0002 for L, a, b, respectively), providing evidence for a synergistic effect and not for a saturation effect. MRS showed that the highest redness of yolks was reached with 1.5 mg/hen/d of yellow and 0.5 mg/hen/d of red xanthophylls. So, higher supplementations aiming at increasing yolk color would bring an unnecessary cost to the ration. The most accepted yolk color scored 9, which corresponded to mean color attributes L = 65; a = 16; and b = 64. MRS showed that these values could be reached with combinations of yellow:red xanthophylls like 1.0:0.15 or 1.5:0.1 mg/ hen/d or simply with the yellow xanthophylls at 2.0 mg/hen/d. So, it was concluded that both yellow and red xanthophylls are important to define yolks color; that high amounts of xanthophylls are unnecessary to bring changes to color; and that Brazilian consumer requires yolks color attainable with few amounts of red xanthophylls or only with the yellow ones.

Spectrophotometric evaluation of color changes of esthetic brackets stored in potentially staining solutions

The purpose of this study was to evaluate, in vitro, the chromatic behavior of esthetic brackets stored in potentially staining solutions. The sample were divided into four groups according to the commercial brand and stored in four different solutions (distilled water, cola soda, coffee and mouthrinse) at 37°C for 14 days. Possible color changes measured according to the CIE L*a*b* color system with a spectrophotometer at five intervals of time after storage. The statistical analysis was carried out using ANOVA to 1%, Tukey's tests and decomposition of interactions with a significance level of 5%.The color changes were dependent on the solution, storage time and the brand of brackets. The largest color changes were observed in the G3, followed by G2, G1/G4. The esthetic brackets do not present satisfactory and stable chromatic behavior.

Discrimination of production environments of specialty coffees by means of stable isotopes and discriminant model

The south of Minas Gerais, Brazil stands out among various regions through its capacity for production of specialty coffees. Its potential, manifested through being one of the most award-winning Brazilian regions in recent years, has been recognized by the Cup of Excellence (COE). With the evident relationship between product quality and the environment in mind, the need arises for scientific studies to provide a foundation for discrimination of product origin, creating new methods for combating possible fraud. The aim of this study was to evaluate the use of carbon and nitrogen isotopes in discrimination of production environments of specialty coffees from the Serra da Mantiqueira of Minas Gerais by means of the discriminant model. Coffee samples were composed of ripe yellow and red fruits collected manually at altitudes below 1,000 m, from 1,000 to 1,200 m and above 1,200 m. The yellow and red fruits were subjected to dry processing and wet processing, with five replications. A total of 119 samples were used for discrimination of specialty coffee production environments by means of stable isotopes and statistical modeling. The model generated had an accuracy rate of 89% in discrimination of environments and was composed of the isotope variables of δ15N, δ13C, %C, %N, δD, δ18O (meteoric water) and sensory analysis scores. In addition, for the first time, discrimination of environments on a local geographic scale, within a single municipality, was proposed and successfully concluded. This shows that isotope analysis is an effective method in verifying geographic origin for specialty coffees.

From Token, to Pioneer, to Crusader: Survival Strategies for Faculty of Color in PWI's

As the only person of color in your workplace you may experience feelings of isolation and hopelessness. However, it is possible to survive this situation. To do so, you must go .through an empowering developmental process. You no longer have to be a Token. Learn how you can become a Pioneer and a Crusader for social justice.