Efeito das variáveis laboratoriais protéticas na adesão da porcelana com ligas de níquel-cromo

The metalceramic crowns are usually used in dentistry because they provide a resistant structure due to its metallic base and its aesthetics from the porcelain that recovers this structure. To manufacture these crowns, a series of stages should be accomplished in the prosthetic laboratories, and many variables can influence its success. Changes in these variables cause alterations in the metallic alloy and in the porcelain, so, as consequence, in the adhesion between them. The composition of the metal alloy can be modified by recasting alloys, a common practice in some prosthetic laboratories. The aim of this paper is to make a systematic study investigating metalceramic crowns as well as analyzing the effect of recasting Ni-Cr alloys. Another variable which can influence the mechanism of metalceramic union is the temperature used in firing porcelain procedure. Each porcelain has to be fired in a fixed temperature which is determined by the manufacturer and its change can cause serious damages. This research simulate situations that may occur on laboratory procedures and observe their consequences in the quality of the metalceramic union. A scanning eletron microscopy and an optic microscopy were accomplish to analyse the metal-ceramic interface. No differences have been found when remelting alloys were used. The microhardness were similar in Ni-Cr alloys casted once, twice and three times. A wettability test was accomplished using a software developed at the Laboratório de Processamento de Materiais por Plasma, on the Universidade Federal do Rio Grande do Norte. No differences were found in the contact angle between the solid surface (metallic substratum) and the tangencial plane to the liquid surface (opaque). To analyse if the temperature of porcelain firing procedure could influence the contact area between metal and porcelain, a variation in its final temperature was achieve from 980° to 955°C. Once more, no differences have been found

Marcadores nutricionais e inflamatórios e sua associação com a morbimortalidade em hemodiálise

Background: Malnutrition, inflammation and comorbidities are frequent in patients with chronic renal failure in hemodialysis (HD), contributing for morbidity and mortality. Aims: To evaluate the correlation between anthropometric, laboratory parameters, bioelectrical impedance (BIA) and inflammatory markers with the morbidity and mortality of patients in HD, as well as the impact of its alterations throughout 12 months. Methods: 143 patients of a dialysis facility in Northeast Brazil were evaluated throughout 18 months. Patients with more than 3 months on dialysis, older than 18 years, without amputation of hands and feet, were included in the study. We performed a clinical (subjective global assessment - SGA), anthropometric (BMI, percent of ideal weight, MAC, MAMC, MAMA, percent of fat mass and TSF), laboratory (albumin, creatinine, lymphocyte count as nutritional markers and CRP, IL-6 and TNF- as inflammatory markers) evaluation and BIA (reactance, phase angle and percent of body cell mass) at the beginning of study and after 3, 6 and 12 months of follow-up. The association between study variables and deaths and hospitalizations in 6 and 12 months was investigated. The variable with significance < 10% in the univariate analysis had been enclosed in a multivariate logistic regression analysis. We also investigated the risk of mortality and hospitalization associated with differences in measurements of the variables at baseline and six months later. Results: Patients were aged 52.2 ± 16.6 years on the average, 58% were male, and mean dialysis vintage was 5.27 ± 5.12 years. The prevalence of malnutrition varied from 7.7-63.6%, according to the nutritional marker. The variables associated with morbidity and mortality in 6 and 12 months had been creatinine ≤ 9.45 mg/dl, phase angle ≤ 4.57 degrees, BMI ≤ 23 kg/m2, age ≤ 64.9 years, reactance ≤ 51.7 ohms; Charlson´s index ≥ 4 and socioeconomic status ≤ 7. During six months of follow up, decrease in albumin was associated with significantly higher mortality risk. Conclusions: This study detected that the best predictors of morbidity and mortality between nutritional and inflammatory markers are phase angle, reactance, creatinine and BMI and that changes in albumin values over six 107 months provide additional prognostic information. The authors believe that parameters of BIA may detect early changes in nutritional status and emphasize that longitudinal studies with larger number of patients are necessary to confirm these data and to recommend BIA as a routine nutritional evaluation in HD patients

Desenvolvimento de um rastreador solar do tipo polar com ajuste do ângulo de inclinação

The use of solar energy for electricity generation has shown a growing interest in recent years. Generally, the conversion of solar energy into electricity is made by PV modules installed on fixed structures, with slope determined by the latitude of the installation site. In this sense, the use of mobile structures with solar tracking, has enabled increased production of the generated energy. However, the performance of these structures depends on the type of tracker and the position control used. In this work, it is proposed position control a strategy applied for a solar tracker, which will be installed in Laboratory of Power Electronics and Renewable Energy (LEPER), located in the Federal University of Rio Grande do Norte (UFRN). The tracker system is of polar type with daily positioning east-west and tilt angle manual adjustment in the seasonal periods, from north to south

Desempenho de um painel fotovoltaico de baixa tensão, acoplado ao protótipo de um conversor dc/dc topologia Booster

Low voltage solar panels increase the reliability of solar panels due to reduction of in series associations the configurations of photovoltaic cells. The low voltage generation requires DCDC converters devices with high efficiency, enabling raise and regulate the output voltage. This study analyzes the performance of a photovoltaic panel of Solarex, MSX model 77, configured to generate an open circuit voltage of 10.5 V, with load voltage of 8.5 V, with short circuit current of 9 A and a power of 77 W. The solar panel was assembled in the isolated photovoltaic system configuration, with and without energy storage as an interface with a DCDC converter, Booster topology. The converter was designed and fabricated using SMD (Surface Mounted Devices) technology IC (integrated circuit) that regulates its output voltage at 14.2 V, with an efficiency of 87% and providing the load a maximum power of 20.88 W. The system was installed and instrumented for measurement and acquisition of the following data: luminosities, average global radiation (data of INPE Instituto Nacional de Pesquisas Espaciais), solar panel and environment temperatures, solar panel and DC-DC converter output voltages, panel, inverter, and battery charge output currents. The photovoltaic system was initially tested in the laboratory (simulating its functioning in ideal conditions of operation) and then subjected to testing in real field conditions. The panel inclination angle was set at 5.5°, consistent with the latitude of Natal city. Factors such as climatic conditions (simultaneous variations of temperature, solar luminosities and ra diation on the panel), values of load resistance, lower limit of the maximum power required by the load (20.88 W) were predominant factors that panel does not operate with energy efficiency levels greater than 5 to 6%. The average converter efficiency designed in the field test reached 95%

Efeitos da inclinação da esteira na marcha de indivíduos hemiparéticos crônicos

Objective: To examine the effects of treadmill inclinations on the walking of hemiparetic chronic subjects. Design: Observational descriptive study. Location: Laboratory of human movement analysis. Participants: Eighteen subjects, 10 men and 8 women were evaluated, with a mean age of 55.3 ± 9.3 years and the time since the injury of about 36 ± 22.8 months. Intervention: Not applicable. Main Outcome Measures: All subjects were evaluated for functional independence (Functional Independence Measure - FIM) and balance (Berg Balance Scale). Angular variations of the hips, knees and ankles in the sagittal plane were observed, as well as the speed of the movement (m/s), cadence (steps/min), stride length (m), cycle time (s), step time on the paretic leg and on the non-paretic leg (s), support phase time and balance phase time on the paretic leg (s) and the ratio of symmetry inter-limb as subjects walked on a treadmill at three conditions of inclination (0%, 5% and 10% ). Results: There were angular increases in the initial contact of the hip, knee and ankle, amplitude increase in the hip between 0% and 10% (37.83 ± 5.23 versus 41.12 ± 5.63, p < 0,001) and 5% and 10% (38.80 ± 5.96 versus 41.12 ± 5.63, p = 0,002), amplitude increases in the knee between 0% and 10% (47.51 ± 15.07 versus 50, 30 ± 12.82, p = 0,040), extension decreases in the hip, dorsiflexion increases in the balance phase and in the time of support phase from 0% to 5% (0.83 ± 0.21 versus 0.87 ± 0, 20, p = 0,011) and 0% and 10% (0.83 ± 0.21 versus 0.88 ± 0.23, p = 0,021). Conclusion: The treadmill inclination promoted angle changes as such as the increase of the angle of the hip, knee and ankle during the initial contact and the balance phase and the increase of the range of motion of the hip and knee; furthermore, it also promoted the increase of the support time of the paretic lower limb

Síntese enzimática de biosurfactante e sua aplicabilidade na indústria do petróleo

Enzymes have been widely used in biosynthesis/transformation of organic compounds in substitution the classic synthetic methods. This work is the first writing in literature of enzymatic synthesis for attainment the biossurfactants, the use glucose sucrose, ricinoleic acid e castor oil as substratum, and as biocatalyst, used immobilized lipase Thermomyces lanuginose, Rhizomucor miehei and the Candida antarctica lipase B; alkaline protease and neutral protease from Bacillus subtillis and yeast Saccharomyces cerevisiaeI. The analysis of HPLC (high performance liquid chromatography) showed that highest conversions were reached of used the alkaline protease from Bacillus subtillis. Laboratory tests, to evaluate the applicability, indicated that the produced biosurfactantes had good stability in presence of salts (NaCl) and temperature (55 e 25°C), they are effective in the reduction of the superficial tension and contac angle, but they have little foaming capacity, when compared with traditional detergents. These results suggest that the prepared surfactants have potential application as wetting agent and perforation fluid stabilizer